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 Lectures on diseases of the digestive or 
 
 3 1924 012 160 226 
 
E If 
 
^//s 
 
 THE I^EW SYDENHAM SOCIETY. 
 
 Instituted MDOOCLVIII. 
 
 VOLUME OXXXVI. 
 
The original of tliis book is in 
 tlie Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31924012160226 
 
LECTUEES 
 
 ON 
 
 DISEASES OF THE DI&ESTIVE 
 ORGANS. 
 
 EXTBA-OBDINAET PeOFBSSOB IN THE UNIVBESITY AST) PHYSICIAN TO THE 
 
 AtTGUSTA Hospital, Bbelin. 
 Translated from the latest German Bdition 
 
 ROBERT SAUNDBT, M.D. Edin., F.R.O.P. Lond, 
 
 Physician to the General Hospital, Birmingham. 
 
 VOL. I. 
 
 LECTURES ON DIGESTION. 
 
 '%axihm : 
 THE NEW SYDENHAM SOCIETY. 
 
 MDCCCXOI. 
 
A. ^^^ 
 
 a^o 
 
 I ' ^ o^'K \r: 
 
 LONDON: 
 
 Printed by Jab. Tbtjscott & SoH, 
 
 Suffolk Lane, City. 
 
 C>\ 
 
PREFACE TO THE ENGLISH EDITION. 
 
 rPHE publication of a work by the New Sydenham Society 
 -*- indicates such a kindly appreciation of its merits by eminent 
 members of our profession, and is such an honourable recognition 
 of the author, that it is his first and plainest duty to give expres- 
 sion to his sincere thanks and gratification at the distinction 
 shown to him. Whilst I do this with all my heart, I hope that 
 the reception of these " Lectures on Diseases of the Digestive 
 Organs" may be as favourable in England as elsewhere. I 
 was not led to concern myself with the disorders of digestion 
 by clinical study. My way led through physiology, and 
 when, in 1879, I published the first edition of the first part of 
 these lectures, the diseases of the digestive organs were just 
 beginning to be studied by means of new methods of investiga- 
 tion. I happened to take a modest share in this work, and half 
 against my will I gathered a large practical experience. The 
 " Diseases of the Stomach " is a review of these methods, and a 
 statement of their pathognostic, diagnostic, and therapeutic 
 results. The investigators in this field are still enthusiastic in 
 their work, and in the two years which have passed since the 
 publication of the second German edition of this part, many 
 questions have been cleared up, which then were in the midst of 
 discussion, and much that is new has been added. I have 
 endeavoured to remedy this by making short additions to the 
 text, and I owe special thanks to Dr. Saundby for the great 
 care he has devoted to his excellent translation. I can say 
 
PREFACE TO THE ENGLISH EDITION. 
 
 that on the whole the progress of investigation has confirmed 
 my formerly expressed ideas, and that the later work has not 
 required any important changes. 
 
 Perhaps I am wrong, but it appears to me that the new methods 
 of investigating the activity of the stomach functions have not so 
 far become so popular in England as their diagnostic and thera- 
 peutic worth deserves. It would be a great satisfaction to the 
 author if his book might help to point out how easy these 
 investigations are, and how important, under certain circum- 
 stances, they may become. 
 
 C. A. EWALD. 
 
 Berlin, October, 1891. 
 
TRANSLATOR'S PREFACE. 
 
 I HAVE mucli pleasure in presenting to my English confreres 
 this translation of Professor Ewald's well-known lectures. In 
 1880 I published a translation of the first edition of his 
 " Lectures on Digestion," which constitute Vol. I., but the 
 present translation is from the third German Edition of 1890, 
 which was, to a great extent, re-written and much enlarged. 
 Vol. II. has not been previously translated, and is not familiar 
 to English readers. Without pretending to endorse all it con- 
 tains, I am satisfied that the views expressed are, in the main, 
 sound, consistent, and thoroughly practical. 
 
 Robert Saundby. 
 
 BlKMINGHAM, 
 
 November, 1891. 
 
LECTURES ON DIGESTION. 
 
 LECTUEB I. 
 
 Gentlemen, — More than anywhere else, in diseases of the 
 digestive organs it is possible to avert permanent injury, and to 
 carry out rational and successful therapeutics, by a clear and just 
 appreciation of physiological processes. Digestion is comparable 
 to a complicated clock-work, the derangements of which are 
 readily shown by the movements of the hands, but the causes of 
 which are difficult to discover, from the complexity and concealed 
 position of the movement. Therefore the pathology of digestion 
 requires a well-grounded knowledge of the complex processes 
 which effect the transformation of our food into chyle. 
 
 This is so plain as scarcely to need to be referred to, as it is 
 unintelligible how any one could come to any conclusion as to the 
 causes of defective action in a clock from inspecting the hands, 
 instead of looking at the works. Such superficial inquiry could 
 only lead to blunders. 
 
 But the physiology of digestion has during recent years 
 developed as scarcely any other branch of the subject has done, 
 both in breadth and depth, and a notable list of new observations 
 and brilliant discoveries give it quite another aspect to that which 
 it possessed fifteen or twenty years ago. A great mass of histo- 
 logical and physiological details, which teach us the intimate 
 nature of special processes, and the discovery of chemical facts 
 which have led to the attainment of new general points of view, 
 have much elucidated its aspect, filled up many gaps, and turned 
 the current of investigation into quite new channels. 
 
 The classical works of Joh. Miiller, Tiedemann, Gmelin, 
 Frericbs, Bidder and Schmidt, stand out as landmarks and indi- 
 cations of the contemporary position of science ; but the task 
 belongs to me to follow its development from their time to our 
 
 1 
 
2 LECTURES ON DIGESTION. [Lect. I. 
 
 own. This is a protracted task, owing to the condition of our 
 literature, as the information is scattered through a hundred 
 monographs, periodicals, and reviews. In order that I may give 
 the desired attention to our recent knowledge, and bearing in 
 mind our special object, the relation of derangements of the diges- 
 tion to our knowledge of the normal processes, I think it best, in 
 the following remarks, to treat chiefly of new facts and theories, 
 and to recapitulate briefly what is generally known, as a sort of 
 foundation on which to place our comer-stone. I am anxious, 
 therefore, in the recital of facts, to speak only of the modus 
 operandi in its grosser features', and to give chemical formulae 
 and methods only so far as is necessary to make the subject intel- 
 ligible. On the other hand, I will willingly linger over the 
 clinical aspects whenever a suitable occasion offers for a glance at 
 practical points, and especially from a therapeutic point of view. 
 Proceeding in this fashion, we shall first have to learn not only 
 a general outline of the knowledge we possess, but also the 
 numerous gaps and defects in it, for in order to obtain a clear 
 insight into a subject, the knowledge of our deficiencies is the 
 first step towards progress. 
 
 Let us then see what is understood by the term " Digestion." 
 By digestion is generally meant that which belongs to the 
 animal kingdom — that is to say, the processes by which nutri- 
 ment is prepared for absorption into the circulation, and for 
 further use in the animal economy. Plants do not digest, and 
 have, in an ordinary sense, no digestive organs, so that it might 
 appear that this made a fundamental distinction between the 
 animal and vegetable kingdoms, if we restricted ourselves to 
 the morphological stand-point. But if we regard the digestive 
 process more broadly, as has been done by the genius of Claude 
 Bernard, we see that no such distinction holds good, but that 
 both throughout possess a common type as their base. 
 
 If we follow out the processes of digestion from the surface of 
 the alimentary canal of an animal, by which the crude nutriment is 
 changed into material for cell-nutrition, and the changes it under- 
 goes in the various organs, or in the circulation, or finally in the 
 cells themselves, we perceive that it may be divided into two 
 kinds. Superficial and Interstitial, and that these are present in 
 plants as well as in animals. Certainly in very different degrees, 
 for it must not be forgotten that the process of digestion in 
 
GENERAL STATEMENTS. 6 
 
 plants is concerned in assimilating not complex organic mole- 
 cules, but easily diffusible gases and simple compounds, chiefly 
 carbonic acid and water, with salts in solution. 
 
 Superficial digestion occurs on the surface of organs or organ- 
 isms, and is that which we call digestion in its proper sense in 
 animals. As the intestinal tract is formed by a canal open above 
 and below, into which the various glands of the body debouch, 
 we may regard the treatment of nutriment in the stomach and 
 intestine of animals as a superficial process taking place on an 
 inner surface of the body. In this respect there is a great 
 analogy with plants, i.e., a superficial digestion occurs, though of 
 not nearly so obvious a kind as in animals. For plants which 
 have no chlorophyll it is apparently the rule and first condition of 
 life. Yeast cells, for example, require for their nutriment a 
 solution of invert sugar, a mixture of dextrose and l^vulose, and 
 cannot grow in a pure solution of cane sugar. But each yeast 
 cell possesses the power of converting cane sugar into invei't 
 sugar, which is a kind of superficial digestion, a process effected 
 by means of a ferment quite analogous to that which occurs in 
 animals. But higher plants also present the same relations. 
 
 By the beautiful researches of Darwin we are familiar with the 
 processes in the so-called insectivorous plants, the Drosera rotundi- 
 folia, the Bionioea muscipula, &c., and we know that their leaves 
 possess the power of secreting a peculiar acid juice which flows 
 over small insects entangled and held fast in the leaf-hairs, or 
 pieces of albumen laid upon them, and prepares them for absorp- 
 tion by the leaf-vessels. These peculiar relations of the leaf 
 surface offer a complete analogy to the stomach digestion of 
 animals, especially of the lower animals, where, as in the amoeba, 
 any part of the surface of the body may by invagination form a 
 sort of stomach for the reception of nutriment. 
 
 There can be no doubt, therefore, that superficial digestion in 
 its essential form does occur in plants, so that we cannot regard 
 this kind of digestion as exclusively the property of animals. 
 But all this is true in a much higher and mOre complete degree 
 of interstitial digestion, indeed the relation between the vegetable 
 and animal kingdom is almost reversed. Plants and animals 
 store up in their cells a wealth of nutriment, so that they can 
 exist for a certain time, some more, others less, without taking 
 in nutriment. This material, deposited in an insoluble form, 
 
4 LECTURES ON DIGESTION. [Lect. I. 
 
 undergoes changes by the action of ferments into soluble pro- 
 ducts, which pass into the circulation, forming a sort of digestion 
 not to be distinguished from the kind previously described, 
 except that it is not performed in special organs, but may take 
 place in every cell in the organism, and commit its products 
 direct to the interstitial circulation. This it is which was called 
 by Claude Bernard interstitial digestion. It deals with carbo- 
 hydrates, albuminates, and fats in special ways, of which we only 
 know exactly the fate of the carbo-hydrates. They are developed 
 most widely in the vegetable kingdom, where from their special 
 prominence they must play a most important part ; but they are 
 to be met with in the same fashion in animals. 
 
 The change in the sprouting nodes of plants of insoluble starch 
 in soluble sugar, and the transformation of glycogen in the liver 
 cells of animals into grape sugar, which is known to disappear in 
 starved animals, are processes of fermentation which unquestion- 
 ably may count as digestive actions, in so far as they prepare for 
 circulation in the blood or sap the nutritive material stored up 
 in the cells, and so further tissue change. We do not, however, 
 possess equally trustworthy data respecting albuminates and fats, 
 for we can at most regard only as probable the absorption of 
 peptone and its retro-metamorphosis into albumen, described by 
 Hofmeister as effected by the adenoid tissue of the intestinal 
 mucous membrane, though many facts suggest that in this process 
 there enter fermentative decompositions and changes in cell-life. 
 
 I hope these few facts will suffice, gentlemen, to give you a 
 general notion of the meaning of the word digestion, and to show 
 you that no sharp distinction can be made between the animal 
 and vegetable kingdoms in this respect. It is important to show 
 you now the extraordinary range and great significance of those 
 processes which are concerned in converting the crude organic 
 nutriment into special forms for the use of the cells, and the uni- 
 form principle that all these processes are in some manner 
 peculiar. They are in the last instance always fermentative pro- 
 cesses, by w'hich Nature is served for this purpose throughout the 
 entire realm of the organic world, and a proper acquaintance 
 with the importance of digestion is directly bound up with a 
 clear and precise knowledge of the importance of fermentative 
 action. 
 
 Frankly, in digestion we have only to do with the reception 
 
DIGESTION OF INORGANIC SUBSTANCES. O 
 
 and preparation of organic materials. Plants and animals derive 
 their nutriment from the organic and inorganic world. But the 
 digestion of inorganic matter in the animal economy is only of 
 secondary interest, if we except the very important relations of 
 certain chlorides to the hydrochloric acid of the gastric juice. 
 
 We have not now to examine closely the fate of nutriment 
 which has passed into the juices and tissues of the body, and the 
 nearly related but not now in question subject of tissue change, 
 in which assuredly the inorganic matter plays a very important 
 part, but we must learn the necessary preliminary steps, that is, 
 the proceedings by which the organism converts various food 
 stuffs into absorbable material. The great part of this has, how- 
 ever, little to do with inorganic bodies, so that we need devote 
 only a few words to them. 
 
 Inorganic bodies are taken in the form of water and salts with 
 the food. Water, the importance of which is too lightly appre- 
 ciated, although it constitutes 80 per cent, of our tissues, quite 
 independent of the fact that it acts as a medium of solution for 
 the different matters in the exchange between the lumen of the 
 alimentary canal and the vessels, in recent times has received 
 new importance from the part it is shown to play in the fermen- 
 tative processes going on everywhere. The salts undergo certain, 
 decompositions according to their affinities, but otherwise suffer 
 no changes. So far as they are soluble in water and diffusible 
 through animal membrane, they are absorbed, turned to account 
 in the organism, and the remainder passed out with the different 
 excretions. So far as they are not soluble, they pass straight 
 through the alimentary canal, and are able, wherever they may 
 lodge, to give rise to mechanical derangements — as, for example, 
 the little soluble phosphate of magnesia frequently forms the 
 nucleus of an intestinal calculus. It is quite otherwise with 
 organic matter. Besides certain organic acids, such as acetic, 
 malic, lactic, butyric, &c., which so far behave like the inorganic, 
 we can recognise four fundamental types under which we may 
 group the most diverse forms and compounds which make up the 
 chaos of our aliment. But the albuminates, gelatines, carbo- 
 hydrates, and fats, with few exceptions, are not assimilable as 
 such, so that the chief part of the digestive function is the meta- 
 morphosis of these into absorbable modifications. The principal 
 means by which the organism performs this duty is by the action 
 
6 LECTURES ON DIGESTION. [Lect. I. 
 
 of ferments. Only by the changes whicli albumen, fat, and starch 
 undergo through these ferments does it happen that they can 
 pass from the intestine into the lacteals ; without the action of 
 ferments the nutrition and life of the organism would be impos- 
 sible. Allow me, therefore, first shortly to sketch the doctrine of 
 ferments and the role which they play in the animal organism. 
 They have, at the same time, a general interest not limited to 
 digestion alone, inasmuch as, as has been recently especially in- 
 dicated by Hoppe-Seyler and Nencki, they take part in the 
 comhustion processes of the organism. 
 
 Lavoisier and Laplace founded on their great discoveries the 
 doctrine of animal heat as a combustion lyrocess, in which the 
 animal gives out as much heat as it can form by combustion of 
 carbon, which may be fou.nd as carbonic acid in the expired air ; 
 while Magnus's investigations on the diiferent carbonised and 
 oxidised contents of venous and arterial blood localised this com- 
 bustion process in the capillaries ; so the view stood apparently 
 incontrovertible, that the oxygen taken in by the lungs burns the 
 carbon-containing elements of the blood. This process forms in 
 the last instance carbonic acid and water, and, as far as the nitro- 
 genous material is concerned, the products of the so-called retro- 
 gressive metamorphosis. This hypothesis seemed so well founded 
 and was so well supported, that, for instance, Liebig believed 
 that on. deeper respiration, and consequently increased introduc- 
 tion of oxygen, an immediate increased combustion must ensue, 
 and most physiologists and physicians compared the lungs " to 
 bellows which make a fiercer fire in the forge the more they are 
 blown," notwithstanding the fact that the above quoted investi- 
 gations of Magnus had shown that the oxidation processes take 
 place not so much in the blood as in the fixed tissues. But in 
 recent times a reaction has taken place against this long domi- 
 nant explanation. Pfliiger and his school have adopted the view 
 that the cells are, in a certain sense, independent, so far as their 
 function is concerned, of the quantity of oxygen introduced into 
 the blood, somewhat as a mill by the damming of the mill-stream 
 must be driven, whether there is more or less water. Then the 
 gas tension of the cells, that is the carbonic acid produced in 
 them by the action of oxygen, increases with their activity, and 
 can, as I have proved, reach its greatest height in fever. The 
 increased taking up of oxygen (Colasanti, Finkler, Lilienfeld) is 
 
OXIDATION PROCESSES. / 
 
 also in sucli cases not the cause but the result. The factors 
 which regulate the intensity of the combustion process lie in the 
 . cells, and the degree of oxidation is the expression of their vitality 
 and the consequence of the condition or state of their proto- 
 plasm. The carbonic acid, on the other hand, as Hermann has 
 proved in excised frog's muscle, and Pfliiger in living cold- 
 blooded animals, is independent of the presence of oxygen in the 
 surrounding air, so long as the tissues retain a store of oxygen, 
 and its production is not to be regarded as a 'direct oxidation, but 
 rather as a process of dissociation. 
 
 If the view is no longer tenable, that the oxidation processes 
 in the cells are a more or less direct result of oxygen taken up by 
 the blood, and the earlier somewhat rough notion of the process 
 of oxidation is corrected, on the other hand, chemical facts are 
 known which do not conform to the view that oxidation only goes 
 on in the blood and tissues. The following facts are of this 
 order : 1. Neither albumen nor fat, under ordinary conditions, as 
 they are present in the blood, can combine with atmospheric 
 oxygen. This occurs only when the oxygen exists as ozone, a 
 body which, as Pfliiger, in opposition to A. Schmidt and 
 Huizinga, has shown, has not yet been proved to be present in 
 the blood. If we extract the oxygen out of the blood into a 
 Torricellian vacuum by an air-pump, at the base of which a slip 
 of guaiacum paper is fastened, no blue colouration occurs, as I 
 have convinced myself in two experiments, following Pokrowsky. 
 Moreover, according to Rajewsky, the friction which the blood 
 undergoes in the capillaries is not sufficient to form ozone, as 
 might be suspected from analogous facts. The oxygen circulates 
 in the blood in the form of oxyhemoglobin, but this is so easily 
 decomposed, and gives up its oxygen to fluids free from oxygen, 
 that the oxidations which appear to take place in the bodies 
 of animals, cannot, according to Hoppe-Seyler, be effected by 
 a solution of oxy haemoglobin. 2. Certain processes take place 
 in the blood, which cannot be regarded as oxidations but as 
 reductions, such, for example, as the formation of urobilin 
 (hydrobilirubin) from h^mochromogen (the colouring matter 
 of the blood corpuscles), and the formation of hippuric acid 
 out of kinic acid, when this substance is introduced into the 
 blood. 3. Various very easily oxidisable substances, as, for 
 example, pyrogallic acid or pyrocatechin, both derivatives of 
 
8 LECTURES ON DIGESTION. [LecT. I. 
 
 benzol, probably pass unchanged ttrough the blood, and are 
 excreted in the urine in the form of dichotomised sulphuric acid. 
 For all that, a solution of pyrogallic acid in an alkaline fluid 
 takes up oxygen, and changes with such extraordinary energy 
 that it is employed for the quantitative estimation of this gas in 
 the atmosphere. 4. There can be no doubt that a part, or 
 perhaps the whole of the albumen which comes into the circula- 
 tion is not burnt up, but is at first split up into complex bodies, 
 some containing much carbon and hydrogen, others nitrogen, of 
 which only the former are oxidised, the latter being converted by 
 synthesis, or by giving up water, and under certain circumstances 
 carbonic acid into urea. In this way the undoubted conversion 
 of albumen into fat may take place, it being formed from the 
 non-nitrogenous portion of the albumen molecules. E. Baumann 
 thinks he has discovered such a splitting up in urine, where the 
 so-called ether-sulphuric acid appears in the urine as sulphocar- 
 bolate of potash. In this case the phenol is split off from 
 the albumen of the food by decomposition in the intestine, and 
 absorbed. Moreover, if we can accept Salkowski's statement 
 that urea may be formed from nascent hydrocyanic acid and 
 water, the former may originate in the splitting of albuminous 
 bodies. We have better evidence of the formation of urea out of 
 ammonia salts (Salkowski, Schmiedeberg, and Hallervorden), 
 and in birds, of uric acid out of ammonia salts (Minkowski), and 
 by V. Schroeder the liver has been shown to be the seat of uric 
 acid formation. So far the general result of these researches has 
 been to show that each molecule of albumen circulating in the 
 organism is not straightway oxidised, but that it undergoes a 
 complicated process of splitting, combining, oxidation and reduc- 
 tion. If we consider these four points, certain comments suggest 
 themselves on the first and second heads. Nothing opposes the 
 supposition that the protein substances, fat, &c., undergo, as the 
 starting-point of the cell activity, a peculiar unknown intramole- 
 cular change, which facilitates combustion by the neutral oxygen. 
 As an example of such sudden cell activity, I would quote the 
 play of colours in the pigment cells of many animals, which often 
 depends upon a sudden re-arrangement or change of the cell 
 contents. 
 
 On the other hand, both the last points seem to be so impor- 
 tant, that I give you the equations according to which these 
 
REDUCTION PHENOMENA. » 
 
 reduction phenomena occur outside the organism in the presence 
 of reducing substances. 
 
 1. The reduction of kinic acid to hippuric acid. 
 
 Kinic acid+hydriodic acid=benzoic acid + water + iodine. 
 Cj H« 0„+ 2 HI i=C7 Ho Oj +4(HjO)+I. 
 
 A similar reducing process occurs, in the organism as Meissner, 
 Sheppard, and Stadelmann have shown, whereby instead of hydri- 
 odic acid a still unknown reducing action of the intestinal con- 
 tents takes place, which, in accordance with recent discoveries, 
 we must regard as a phenomenon of bacterial life. 
 
 The benzoic acid combines with the glycocoll present in the 
 organism, and forms 
 
 Benzoic acid + glycocoII=hippuric acid + water. 
 C; He 0, 4 C, H, NO,=Co H, NO3 +H, 0. 
 
 2 . The reduction of the colouring matter of the blood corpuscles, 
 heemochromogen, into biliary colouring matter and urine colour- 
 ing matter (bilirubin and urobilin or hydrobilirubin), by the use 
 of nascent hydrogen, a very energetic reducing agent, has been 
 recorded by Hoppe-Seyler. As to the final fate of albumen we 
 know that the cyanogen compounds may very easily represent 
 albumen, or nearly related substances. 
 
 According tQ E. Salkowski, by the action of two cyanide mole- 
 cules on each other urea is formed as follows : — 
 
 Hydrocyanic acid + hydrocyanic acid + water^urea + carbon dioxide. 
 CO NH CO NH H, CON^ Hj CO^. 
 
 Phenomena like the preceding, noticed under 3 and 4, are not 
 reconcilable with the view that the elements of the blood and 
 tissues exclusively support very energetic and rapid oxidising 
 processes. It may, therefore, not seem strange under these 
 circumstances that Hoppe-Seyler observes in support of his 
 theory, as Kiinkel, on theoretical grounds, and as the result of 
 direct investigations, has lately suggested, that heat is given off 
 in all fermentation processes, and that this may be the source of 
 animal heat. In the second place, in all fermentations atomic 
 hydrogen is given up, and reducing processes go on, whilst in 
 consequence of this nascent oxygen is set free, and assumes the 
 part of an energetic oxidising agent, giving rise to a series of 
 
10 LECTURES ON DIGESTION. [Lbot. I. 
 
 chemical processes, such as the formation of anhydrides, alde- 
 hydes, and higher oxidation stages. As is directly proved by 
 the nature of resulting products in the decomposition of albumen 
 by putrefactive organisms, reduction and oxidation must go on 
 side by side, a process which finds its analogue in numerous 
 chemical reactions, of which I will only instance the destruction 
 of albumen by caustic potash. Here, as there, we have at the 
 same time the products of reduction and oxidation, and indeed, 
 what is very noteworthy, in the case of bacterial putrefaction, 
 without the intervention of the atmospheric oxygen. 
 
 As Nencki, in a series of chemical examples, has suggested, it 
 may be that we have a splitting of water into atomic hydrogen 
 (H), and hydroxyl (HO), by which a double action of oxidation 
 and reduction is rendered possible.* 
 
 The piitrefactive processes are provisionally inseparable from 
 the life of the accompanying organism, and what we call putre- 
 faction is a perfectly definite vital process. It cannot advance 
 TOur knowledge of the subject to apply putrefactive processes to 
 explain vital processes, as each is, after all, only a special form 
 of vital activity. Nevertheless, we may compare these processes 
 with the object of improving our knowledge, and I believe 
 Hoppe's theory should be accepted in this sense. I will there- 
 fore adduce facts which are able to further this object very 
 greatly, and also fall into the category of fermentative processes. 
 
 * Such an example is the splitting np of amidocapronic acid or leucin 
 (Cj H,3 NO2) into valerianate of ammonia (C3 H,3 NO2), carbonic acid (CO3 H^), 
 and hydrogen (H^), by decomposition of water, which may be understood in the 
 following way : — 
 
 Amidocapronic acid. Oxycapronic acid, 
 
 CHjCNH,) \ H / Ammonia CHj (HO) 
 
 I + HO = NH3 + 
 
 C5 H, O., C, Hg O, 
 
 and : 
 Oxycapronio acid Methylenglycol. Valerianic acid. 
 
 CHj (HO) + \ HO/ = CH2 (HOJ + G, H,„ 0., 
 
 I H 
 
 C5 Hg O2 
 
 Valerianic acid combines with ammonia to form valerianate of ammonia 
 (C.i H,(, O2— NHj). Methylenglycol, an unstable compound, splits into formalde- 
 hyde and water, and by taking up hydroxyl and hydrogen forms carbonic acid and 
 hydrogen as follows : — 
 
 )Z{ - ^^-^ - y^^ = C03H. + 2(H,) 
 / H \ 
 
THE FERMENTATION THEORY, ETC. 11 
 
 I shall return to this subject. For the present, it is enough to 
 have drawn your attention to the example of animal heat, which 
 touches one of the greatest and most important questions in the 
 animal economy, on the bearing of our knowledge of fermenta- 
 tions. It is not long since that we included in the area of 
 fermentative actions a definite group of diseases, the so-called 
 infectious or zymotic diseases, and ascribed a direct causal con- 
 nection to them, so that the typical derangements of the normal 
 course of the vital processes, such as we have in certain patho- 
 logical processes spreading by " contagion," were regarded as 
 fermentations. A tangible ground for this fermentation theory 
 would be the existence in each infectious disease of a specific 
 micro-organism, which, as the yeast forms carbonic acid out of the 
 surrounding sugar solution, might give rise to a peculiar fermen- 
 tation in the tissues and juices of the animal body, which would 
 be expressed in the particular pathological process. This view 
 can, however, no longer be held, especially since the important 
 researches of L. Brieger. According to him the action of patho- 
 genic bacteria gives rise not to fermentative processes, but to a 
 poisonous product of tissue metamorphosis of these smallest 
 living things, which gives rise to immediate poisonous action, so 
 that this product is rightly called toxine.* 
 
 Brieger could prove that Koch's cholera bacillus, the typhus 
 bacillus of Koch and Eberth, the staphylococcus pyogenes of 
 Kosenbach, and many others, not only gave rise to characteristic 
 decompositions after the manner of putrefactions, but to direct 
 specific products of a poisonous nature prepared from suitable 
 nutrient fluid, which in part corresponded to already known 
 chemical bodies of a very poisonous nature, penta and tetra- 
 methylendiamine, m.ethylguanidine, &c., in part to new highly 
 poisonous bases corresponding in type to substituted ammonia. 
 It is to these bodies that Brieger applies the name of toxines, and 
 identifies them as typhotoxine, tetanotoxine (tetanin), &c. 
 
 Bjr these investigations for the first time do we obtain some 
 actual knowledge of the specific action of bacteria, and by them a 
 crown is placed on the proud edifice of modern bacteriology, but 
 we are nevertheless obliged to abandon the use of the word 
 zymotic in its old sense, at any rate for infectious diseases. It 
 is at the same time very interesting that in these doctrines, based 
 
 * TOTofoi/ sc. (jjopfj.aKov was tho poison with whioli the ancients smeared their arrows. 
 
12 LECTURES ON DIGESTION. L^ECT. I. 
 
 on exact data, the vague speculations of earlier times join hands 
 with the more certain acquisitions of advancing knowledge. 
 
 The iatro-chemical school, or its head, Van Helmont, in his 
 Ortus Medicinse, used promiscuously the terms fermentatio, 
 digestio, putrefactio ; Becker thought that combustion and fer- 
 mentation were analogous processes ; Lavoisier compared physio- 
 logical combustion to the spontaneous burning of dung at lower 
 temperatures ; Stevenson derived animal heat from fermentations ; 
 and Mitscherlich identified directly life with putrefaction. 
 
 The word "ferment" was used by the alchemists of the 14th 
 and 15th centuries in the sense of a force which, without becom- 
 ing weaker itself, could produce great effects in other masses, a 
 quality which, for example, was sought for in the philosopher's 
 stone. Even in the present day, the definition is current which 
 A. Meyer, a well-known and renowned investigator on this sub- 
 ject, gives in his Chemistry of Fermentation for 1874. It runs 
 thus: "That a number of chemical processes not explicable 
 according to the rule of affinities, owe their occurrence to the 
 presence of certain matter which is not recognisably concerned 
 in the reaction, and the quantity of which stands in inordinately 
 small relation to the magnitude of the chemical processes caused 
 by it." This explanation in part no longer holds good, as we 
 have learnt to regard the majority of fermentative processes as 
 consisting of the splitting up and transposition of water, as above 
 related, but the second part is still correct. But if we keep to 
 the biological standpoint, we may consider it a fact, not quite 
 universal but yet certain, so far as all fermentations in animal 
 bodies are concerned, that fermentations in the presence of water 
 and the ordinary body temperature give rise to extensive chemical 
 processes with the smallest quantity of ferment, processes which 
 without ferments we could only effect by very high tempei'atures 
 and very energetic oxidising or reducing agents. These pro- 
 cesses consist in the decomposition of highly complex compounds 
 into simple molecules with simultaneous increase of water, or, to 
 employ the terms of chemists, in the liyAration of anhyd/rides. 
 But this property, which, figuratively speaking, represents in our 
 organism the flame of a Bunsen's burner, which the chemist 
 needs in order to produce similar effects, is that which must 
 make the activity of ferments appear especially important to us. 
 .\ Six principal properties are common to all ferments: 1. All 
 
PKOPERTIES or FERMENTS. 13 
 
 ferments belong to organic nature. 2. All ferments act only in 
 the presence of water. 3. The sum of the products contains 
 more hydrogen and oxygen, even in the condition of water, than 
 the original matter. 4. All ferments decompose peroxide of 
 hydrogen. 5. All ferments act best at temperatures between 
 30° to 60° 0. (diastase at 70°). They can endure a temperature 
 of— 20° without injury. Paschutin has proved that the specific 
 action of the salivary ferment remains strong up to 55° C. (46° 
 Kjeldahl), but becomes feebler with higher temperatures, and dis- 
 appears at 73°. Invertin loses its capacity for inversion, accord- 
 ing to the researches of A. Mayer, at a temperature between 40° 
 and 50° C. This is only true of watery solutions of ferments ; 
 when dried the so-called soluble ferments of the animal body are 
 not so easily destroyed by heat as was believed at one time. 
 Salkowski has shown that pancreatic ferment may be heated for 
 hours to 160° without losing its specific qualities, and similar 
 observations have been made by A. Mayer, Hiippe, and others, 
 respecting other ferments. 6. Every ferment possesses a specific 
 action, and can produce out of one and the same substance a 
 different result according to its nature. So, for example, a solu- 
 tion of sugar is decomposed by yeast into alcohol and carbonic 
 acid, by inversion into grape sugar and fruit sugar, by the bacilli 
 of milk curdling ferment into lactic acid, by butyric acid ferment 
 into butyric acid, carbonic acid, and hydrogen, and so on. The 
 action of ferments on peroxide of hydrogen is very easy to demon- 
 strate. If we place some commercial peroxide of hydrogen in a 
 test-tube over mercury, and add a few milligrammes of yeast, a 
 development of gas follows very rapidly. This gas is formed by 
 the decomposition of peroxide of hydrogen, and is oxygen in which 
 a glowing match bursts into flame. However, this catalytic 
 property belongs not only to the recognised ferments, but to 
 other compounds, e.g., to blood. 0. Nasse has observed the 
 destruction of peroxide of hydrogen by many animal organs in 
 different degrees, and refers it to the existence of special and 
 otherwise hypothetical ferments, which effect an important part 
 of the current vital processes in the organs and their elements, 
 the cells. Tou see how near this view comes to that of Hoppe- 
 Seyler, although reached from another starting-point. On the 
 other hand, it is very interesting that a series of fermentations 
 proceed in the presence of certain substances, in some cases more 
 
14 LECTURES ON DIGESTION. [Lbct. I. 
 
 Strongly, in others more feebly, or are quite prevented, and tMs 
 action is so manifold according to the kind and concentration of 
 the salts employed, that they are far more physiological than 
 chemical processes, and cannot be expressed by any simple 
 chemical equation. To these belong, according to O. Nasse, 
 Kjeldahl, A. Mayer, and H. Schulz, a number of neutral salts, 
 which have different influences upon different ferments, such as 
 diastase, saliva ferment, pancreas ferment, &c. ; and according to 
 Luchsinger, glycerine injected subcutaneously in great quantities 
 hinders the transformation of liver glycogen into sugar, and pre- 
 vents the occurrence of artificial diabetes (puncture and curare 
 diabetes) ; and here also belong the studies of Chittenden on the 
 influence of hydrochloric acid on the diastatic action of saliva, 
 which is stopped by very small quantities, O'OOOl to 0'0006 per 
 cent., and increased by larger quantities. 
 
 Ferments are the integrated elements of certain vegetable and 
 animal juices and tissues. Their production in a pure condition 
 has extraordinary and hitherto insuperable difficulties, and Hoppe- 
 Seyler has described them shortly " as entirely unknown, quite 
 hypothetical " bodies, which are only known by their actions. 
 But they appear to be allied in their composition to albuminoid 
 bodies. A. Schmidt gives an analysis of the emulsin found in 
 bitter almonds as 0=48-76, H = 7-13, N=14-16, S = l-25, 
 = 18' 70; whilst non-coagulable albumen, according to Dumas 
 and Cahours, has the composition G^=53'7, H=7'l, N^15'8, 
 + S=23'6, S^l'8. It must be remarked that Barth gives the 
 composition of invertin and of the enzyme of yeast, which con- 
 verts cane sugar into invert sugar very differently to the above 
 type, C=43-9, H=8-4, N=6-0, 0=417, and S=0-63, and A. 
 Mayer has denied that pure diastase contains any sulphur. The 
 latter is all the more noteworthy, as sulphur is known to be a 
 constant and characteristic compound of all albuminous bodies. 
 On the other hand, Loew discovered in the pancreas a ferment 
 purified as far as possible from dextrine and gum-like bodies, 
 which contained 0=52-7, H=7-51, N=16-6, + S=23-2, 
 ash=r8 per cent., and comes very near to the composition of 
 albumen given above. At any rate these data on the composi- 
 tion of ferments show that we still are far from having in them 
 chemically pure and well-defined bodies. 
 
BIBLIOGRAPHY. 15 
 
 The references are to authors quoted in the text. The well-known text-books 
 on histology, physiology, and physiological chemistry, as well as the monographs 
 of Frerichs, Bidder and Schmidt, Schiff, Moleaohott, Heidenhain and Maly (in 
 Hermann's Hanb. d. Physiologie, Bd. t.), PlUgge, die Mikroorganismen, 2nd 
 Edition, 1886, are not specially indicated. 
 Hoppe-Seyler, Ueber die Processe der Gahrmigen tmd ihre Beziehnngen zum 
 
 Leben dea Organismus. Pfliiger's Archiv. Bd. xii. Hft. 1. 
 
 Pfliiger. Uebor Wirme und Oxydation der lebendigen Materie. Ibid. Bd. xviii. 
 
 Hft. 7-9. 
 Pfliiger. TJeber die physiologisohe Verbrennung in den lebendigen Organismen. 
 
 Ibid. Bd. X. p. 251. 
 Ewald. Untersuchnngen zur Gasometrie der Transsudate des Menschen. II. 
 
 Eeichert nnd du Bois Eeymond's Archiv. 1876, Hft. 3. 
 
 Huizinga. Chem. biologische Notizen iiber Ozon. Centralbl. f. d. med. Wissen- 
 
 sohaft, 1867, p. 323. 
 Pokrowsky. Zur Frage Uber Ozon im Blute und iiber das Sehicksal des Kohlen- 
 
 oxyds bei CO-vergiftungen. Virchow's Archiv. Bd. xxxvi. p. 482. 
 Eindfleisch. TJntersuchungen Uber niedere Organismen. Virchow's Archiv. Bd; 
 
 liv. pp. 108 and 396. 
 Eajewsky, quoted by Hoppe-Seyler. 
 Hoppe-Seyler. Binfache Darstellung von HarnfarbstofE aus Blutfarbstoff. 
 
 Berichte d. deutsoh chem. Gesellsohaft. Bd. vii. p. 1065. 
 Schutzenberger. Die Giihrungserscheinungen. 1876. 
 A.Meyer. Lehrbuchder Gahrungschemie. Heidelberg, 1874. 
 Pasohutin. Einige Versuche mifc Fermentcn, &c. Eeichert nnd du Bois 
 
 Eeymond's Archiv. 1871, p. 305. 
 Salkowski. ITeber das Verhalten des Pankreasferments bei der Erhitzung. 
 
 "Virchow's Archiv. Bd. cxxx. 
 O. Nasse. TJntersuchungen iiber die ungeformteu Fermenten. Pfliiger's Archiv. 
 
 Bd. xi. p. 138. 
 Hoppe-Seyler. ITeber Giihrungsprocesse. Ztsohrft. f . physiolog. Chemie. Bd. ii. 
 
 p.l. 
 Pr. Hofmeister. TJntersuchungen iiber resorption und Assimilation der Nilhr- 
 
 stoffe. Archiv. f. Exp. Path. u. Pharmakol. Bd. xix., xx., and xxii. 
 
 D. Pinkler. TJeber das Pieber. Pfliiger's Archiv. Bd. xxix. p. 98. 
 G. Colasanti. Ein Beitrag zur Pieberlehre. Ibid. Bd. xiv. p. 125. 
 
 J. Geppert. Die Gase des arteriellen Blut im Fieber. Zeitsohr. f. Klin. Med. 
 
 Bd. ii. p. 355. 
 CI. Bernard. Lefons sur les phe'nom^nes de la vie. 
 Nencki. Ueber den chemiachen Mechanismus der Faulniss. Journal f . Praktiache 
 
 Chemie. N. F. Bd. xvii. p. 105. 
 Nageli. Ueber Gahrungen. p. 45 et seq. 
 A. Kunkel. Ueber Warmebildung bei den Fermentationen. Pfliiger's Archiv. 
 
 Bd. XX. p. 509. 
 L, Brieger. Weitere Unterauohungen Uber Ptomaine. Berlin, 1885, p. 66, and 
 
 other Essays. 
 
 E. Salkowski. Ueber die Wirksamkeit erhitzter Fermente, &c. Virchow's 
 Archiv. Bd. 81, p. 552. 
 
 F. Hilppe. Ueber das Verhalten ungeformter Fermente gegen hohe Tempera- 
 turen. Mittheilungen des Kaiserl. Gesundheitsamtes. 1. p. 339. 
 
16 LECTURES ON DIGESTION. [Lect. I. 
 
 A. Barth. Zur Kenntniss des Invertina. Chem. Beriolite. xi. p. 474. 
 
 A. Mayer. Die Lehre von den ohemisohen Fermenten oder Enzymen. 1882, p. 19. 
 
 P. Ehrlioh. Das Sanerstoff-Bedurfniss des Organismus. Berlin, 1885. 
 
 E. Salkowski. Beitrage zur Theorie d. Harnstoffbildung. Zeitsohr. f. physiol. 
 
 Chemie. Bd. i. and iv. p. 100. 
 E. Hallerrorden. Ueber das "Verhalten des Ammoniaks im Organismns und 
 
 seine Beziehung zur HarnstofEbildang. ArcbiT. f. Exp. Patb. Bd. x. p. 125. 
 T. Scbroeder. Ueber Harnstoffbildung ; iiber die Bildung des Harnstoffs in der 
 
 Leber. Arohiv. f. Exp. Patb. Bd. xt. p. 364, and Bd. xix. p. 373. 
 Minkowski. Einfluss der Leberextirpation auf den Stolfwechsel. Ibid. Bd. 
 
 xxi. p. 41 ; and Ueber die Synthese des Fettes und der Fettsauren im Organ- 
 ismus. Bd. xxi. p. 373. 
 E. Baumann. Ueber gepaarte Sohwefelsauren im Harn ; iiber gepaarte Scbwe- 
 
 felsauren im Organismus. Pfluger's Arcbiy. Bd. xii. p. 69, Bd. xiii. p. 285. 
 H. Schulz. Ueber Hefegifte. Pfliiger's Archiv. Bd. xlii. 
 E. H. Chittenden. Studies from the laboratory of physiol. chemistry of Yale 
 
 University, 1887. 
 0. Loew. Ueber die ohemische Natur der ungeformte Fermente. Pfluger's 
 
 Arohiv. Bd. xxxvii. p. 203. 
 
17 
 
 LECTURE IL 
 
 Gentlemen, — The fact that some fermentations result from 
 animal or vegetable juices and extracts, and others from the 
 functional manifestations of living organisms, has, for a long 
 time, led to their division into organised and unorganised, or, 
 what means the same thing, organic and chemical, direct and 
 indirect, ferments. The organised ferments are, so to speak, 
 identical with the specific organic structures which we always 
 meet with wherever we find the specific action, and are intimately 
 bound up with the " life " of these structures. The alcoholic 
 ferment is extinguished so soon as the yeast cell is dead. The 
 unorganised ferments, which recently, according to the example 
 of W. Ktihne, would be generally described as enzymes, are, once 
 existent, independent of the welfare of the mother substance or of 
 the life of their original producers and bearers. Saliva, gastric 
 juice, pancreatic juice, the extracts of certain seeds, as emulsin, 
 myrosin, &c., remain active after the death of the animal or plant, 
 but it is not important' for our present purpose to decide whether 
 these enzymes are ready formed as such in the glandular apparatus 
 concerned, or exist there only in a previous stage, as inactive zymo- 
 gens, which are changed into active enzymes under pressure of 
 physiological action, if this expression may be allowed. Many facts, 
 which have been recently closely debated, speak in favour of the 
 latter view. But it is questionable whether this is an essential 
 difference, or only a defect in our knowledge, which does not 
 permit us — to keep to the same example — to extract an alcoholic 
 ferment from yeast, as we extract the gastric ferment from the 
 stomach. 
 
 In fact, many considerations favour the view that "it is not 
 permissible to identify a ferment, that is to say, a chemical 
 body which produces decomposition in the fermenting substance, 
 with the organism in which it is formed " (Hoppe-Seyler) ; and 
 " nowhere in the whole series of ferment actions does a specially 
 vital process take place, but everywhere only a chemical process." 
 
 2 
 
18 LECTURES ON DIGESTION. [L^CT. II. 
 
 It is obvious that such an explanation, which regards all ferments 
 from a uniform standpoint as secretions of organisms, and allows 
 no direct part in the ferment action to the cell itself, must greatly 
 facilitate our comprehension of these processes. We may hope, 
 sooner or later, to bring about fermentation without these organ- 
 isms, as we can do now in the case of the " unorganised" ferments. 
 The distinction between " organised " and " unorganised " fer- 
 ments would then completely disappear ; all ferments would be 
 unorganised, only some more, some less, identified with their 
 carriers. The following considerations support this view : 1 . A 
 ferment can be extracted from yeast, which converts Isevulose 
 into dextrose, and is called invertin. 2. There is an alcoholic 
 fermentation without anything to do with yeast cells, which at 
 one time were thought to be necessary elements of this process. 
 Lechartier and Bellamy found that chopped up leaves and fruits 
 of phanerogams formed alcohol without yeast when placed in an 
 atmosphere free from oxygen (carbonic acid), and thus confirmed 
 an earlier observation of Pasteiir. 3. Under certain conditions 
 yeast undergoes a process of self-fermentation, that is, it forms 
 alcohol and sugar out of its own substance without any solution 
 of sugar. According to Bechamp and Schutzenberger, in this 
 way arise many other products of the fermentation of nitrogenous 
 bodies, leucin, tyrosin, sarcin bases, &c., as if there ensued a 
 splitting up of the protoplasm of the yeast into the ordinary 
 results of the tissue-metamorphosis of albumen. According to 
 Nageli, this is not so much the action of the essential ferment 
 of the yeast cells, as the effect of pollution by fissiparous fungi 
 which grow at the expense of the dying yeast cells and destroy 
 their substance. 4. Also the circumstance that alcoholic fermen- 
 tation ceases with the death of the yeast, would be consistent 
 with the existence of a chemical ferment in the yeast, if we admit 
 that the latter is indeed constantly being formed, but in so small 
 a quantity that it is at once used by the fermentation. 6. Some 
 of the fermentative results formed can take place without these 
 latter, by purely chemical means, as for example the conversion of 
 sugar into lactic acid, of alcohol into vinegar, and of urea into car- 
 bonate of ammonia. Further, the circumstance that the chemical 
 means are at hand to imitate the action of organised ferments in 
 test-tubes and retorts without their intervention, does not prove 
 that the action of organised ferments must be due to a substance 
 
CHARACTERS OF FERMENTS. 19 
 
 separable from the life and vital functions of tlie cell, as in tke 
 unorganised ferments, and the observations of Lechartier and 
 Bellamy are capable, as we shall see," of another interpretation. 
 
 There are, therefore, a series of characteristic differences 
 between the organised and the unorganised ferments. The 
 organised ferments multiply to a certain extent during their 
 activity ; the unorganised do not. The organised ferments are, 
 according to a remarkable discovery of P. Bert, killed by oxygen 
 subjected to the compression of many atmospheres ; the unorgan- 
 ised remain uninjured. On the other hand, according to Dumas, 
 borax kills invertin, emulsin, myrosin, and diastase, while it leaves 
 the alcoholic ferments unaffected.* And, finally, all organised 
 ferments require for their origin and the commencement of their 
 activity, as well as for its continuance, the presence of free or 
 combined oxygen ; for instance, yeast does so to such a degree 
 that it is able to convert arterial into venous blood ; whilst the 
 unorganised ferments, according to Hiifner, can work without 
 any oxygen. The last-named properties do not concern so much 
 the hypothetical ferment as the life of the ferment carrier ; but 
 in any case the ferment action comes to an end with the life of 
 the ferment carrier. But this is a point which we are not, at 
 present in a position to discuss. We are not yet in a position 
 to separate the substratum, the living organism, from the essence, 
 the actual specific ferment. The distinction between organised 
 and unorganised ferments exists, as Nencki says, not merely 
 irpocr TjiMcT but ^vcrei (Aristotle). It is the difference between 
 chemical and physiological processes, if for both the same laws 
 hold good. As the yeast decomposes the beer wort into alcohol, 
 carbonic acid, glycerine, and succinic acid, it grows at the 
 same time and forms the elements of its own bodies, 
 cellulose, fat, and probably its special protein. As product of its 
 physiological activity, it secretes invertin, which changes cane 
 sugar into dextrine and Isevulose, just as the germinating seeds 
 of a plant form their soluble ferments in order to dissolve the 
 stored up material and to decompose it. There are other experi- 
 ments known which make the search for such a separation 
 between ferment and ferment carrier appear still more unproduc- 
 tive. The question of the connection of fermentation phenomena 
 
 • According to Pasteur the spores of certain ferment fuugi resist a pressure of 
 ten to twelve atmospheres. Quoted in the Eevue des. scieuo. med. t. xi. p. 336.. 
 
20 LECTUBES ON DIGESTION. [Leot. II. 
 
 — understanding in its widest sense tte action of an organised 
 element — with the physiology of plants (Sachs, PfefFer), may be 
 answered in a tolerably precise manner. We will confine our- 
 selves to the carefully studied alcoholic fermentation as the 
 prototype, but remark expressly, that the data given here 
 respecting that fermentation may be properly applied to ordinary 
 putrefaction, or wherever organised ferments are concerned. 
 Fermentation products are, according to this view, the expression 
 of a progressive metamorphosis of organic matter (carbo-hydrates, 
 proteids) by the oxygen of the air imprisoned in the living cells* 
 of the particular ferment excitor. The products of this meta- 
 morphosis, by the aid of osmosis, get back from the cells into 
 the surrounding medium. They are also, as Boussingault 
 maintains, in a certain degree the secretion of the cells. This 
 metamorphosis of the cell contents, or a part of them, as, for 
 example, in saccharomycetes which produce alcohol and car- 
 bonic acid, is the consequence of one of the self-exhausting 
 processes in the cells, which the vegetable physiologists call 
 "their internal respiration" or " intra-molecular respiration" 
 (Pfeifer). The proximate cause of this is probably the tempera- 
 ture, so that a minimum production of fermentation begins at 
 0°, reaches its maximum at 40° — 50°, and stops altogether at 70° 
 — 75°. But fermentation, or rather its products, are not to be 
 detected, so soon as the oxygen of the air has unrestricted entrance 
 to the fermenting mixture. For all that, this intra-molecular 
 respiration persists during unlimited introduction of oxygen. It 
 does not attain to a concrete expression because its products are 
 arrested by the free oxygen, and ultimately burnt to carbonic 
 acid and water. These two processes, temporarily divided, 
 decomposed into their two phases, indicate that the yeast in a 
 solution of sugar, by respiring free oxygen without forming 
 alcohol, uses just as much sugar as it would use in fermentation. 
 On the other hand, the occurrence of alcohol and sugar in the 
 above-related observation of Lechartier and Bellamy, is nothing 
 more than the consequence of the self-exhausting " intra-molecular 
 respiration " in the cells of the fruits and leaves, which we, if I 
 may use the expression, surprise to a certain extent in its inter- 
 mediate stage when we cut off its necessary oxygen. Under 
 
 * Fermenting yeast cells placed in a solution of sugar in distilled water con- 
 tinue for a long time to form alcohol and carbonic acid. 
 
CHEMICAL THEORY OF FERMENTATION. '2:1 
 
 ordinary circumstances we do not observe this formation of 
 alcohol, because it is oxidised further by the free oxygen of the 
 air, and is decomposed into its ultimate products, carbonic acid 
 and water. The followers of the doctrine of chemical ferments 
 may regard this intra-molecular respiration as the consequence 
 of a special chemical ferment contained in the cell, and accept, 
 as M. Traube does for yeast, a special, as yet hypothetical and 
 undemonstrated, alcoholic ferment, to which view the remark- 
 able researches of L. Brieger quoted in the former lecture, give 
 a quite new and highly important support, in so far as quite 
 definite well-characterised chemical changes or decompositions 
 are proved to be the result of pathogenic micro-organisms. 
 
 Still the two following facts cannot be reconciled with this 
 view : — 
 
 First, it is known that not only yeast becomes useless after 
 a time if it does not get fresh oxygen, but that all ferment- 
 exciting hypho- and schizomycetes are only to a certain degree 
 independent of free oxygen (Buchner) and their growth and 
 their accompanying fermentations are conditioned by it. But 
 there are between the growth of the spores by exclusion of 
 oxygen and the death of phanerogams only quantitative differences, 
 such as exist between the winter sleep of a marmot and the 
 normal tissue metamorphosis of an animal. This is not reconcilable 
 with the properties of unorganised (chemical) ferments, which 
 can carry on their fermentative action unimpaired without 
 oxygen (Hiifner) and within very narrow limits. Secondly, 
 in consequence of Lechartier and Bellamy's observation, we 
 must admit the existence of such a ferment in every cell. 
 Fermentation would be nothing more than " intra-molecular 
 respiration," and we should find ourselves arguing in a circle 
 to which there would be no end. Therefore all tissue meta-. 
 morphoses, which find their limits with the death of the organism 
 and are dependent upon its existence, as the tissue metamor- 
 phoses of the higher plants and animals are dependent upon 
 their lives, and are not capable of being originated apart from 
 the same through their elements, are not to be described as 
 fermentations. " Ferments " in this sense, then, are only the 
 "chemical or unorganised ferments." There are other facts 
 and theories which are not reconcilable with the above definition 
 of all so-called " fermentations." 
 
22 LECTURES ON DIGESTION. [Lect. II. 
 
 It will not have escaped your notice, on calling to mind the 
 views that Pfluger has of late expressed on the subject of animal 
 combustion, that this so-called " intra-molecular respiration" 
 is nothing but the process which Pfluger has described as 
 " dissociations-process " in animal cells, that is, a decomposition 
 of a complex molecule into simple ones, or the intra-molecular 
 striking off of small fragments from larger ones. Pfliiger 
 recognises in it the peculiar essence of all vital processes, the 
 starting-point of the complicated phenomena which make up 
 the life of the individual. 
 
 I am unable to do more than glance superficiall)^ at these 
 far-reaching and important relations, and must leave you to 
 decide, so far as you can, from the facts I have brought before 
 you, in one or the other direction, either for the ubiquity of the 
 enzymes, or are disposed to regard the action of the so-called 
 organic ferments as a physiological action dependent upon and 
 inseparable from the life of the cell.* 
 
 In the meanwhile let us remain faithful to the very convenient 
 division of ferments into organised and unorganised. All purely 
 physiological fermentations in the animal body are due to unor- 
 ganised, and all pathological fermentations to organised ferments. 
 To the enzymes belong the amylolytic, saccharifying, peptonising, 
 and fat-splitting ferments. As prototypes of the organised fer- 
 ments, there is a whole series which all belong to the class of 
 organisms now regarded as fungi, and for the most part are of 
 microscopical dimensions. Here belong, so far as we can observe, 
 yeast (Saccharmnyc.es cerevisice and other forms), the organisms 
 which cause lactic acid fermentation — according to Huppe there 
 are many, chiefly the Bacillus acicIA lactici of Lister and Pasteur 
 — the vinegar ferment, Mycoderma aceti, the bacilli of butyric 
 acid fermentation, Bacillus iutyricus and others, and the numerous 
 bacilli, cocci, and vibriones which cause destruction or putre- 
 faction of proteids, of which we find, for example, in the text- 
 book of Fliigge no fewer than sixteen different kinds described. 
 
 The unorganised ferments are ptyalin in saliva, pepsin in 
 gastric juice, pancreatin or trypsin in pancreatic juice, invertin 
 in the intestinal juice, and a sugar-forming ferment present in 
 fresh bile. These soluble ferments formed in the animal bodies, as 
 already stated, have been recently termed "enzymes." Finally, 
 
 * I do not regard intestinal putrefaction as properly a pljysiologloal process. 
 
SPONTANEOUS GENERATION. 23 
 
 there are the diastatic, inverting, and peptonising ferments in 
 plants, for example in germinating barley, in malt, in many 
 filamentous fungi, in carica papaya, in the already described 
 carnivorous plants, and finally as the products of tissue meta- 
 morphosis in certain fungi. It was never doubted that the un- 
 organised ferments are the products of organic bodies, which can 
 prove their genealogy clearly and distinctly, and which at one 
 point are united to the chain of organic life. It is quite otherwise 
 for the organised ferments. The stringent proof that the putre- 
 fying or fermenting fluids do not contain organised elements 
 within themselves, but that they are introduced from without, is 
 extraordinarily difficult to produce, and has in the shape of the 
 question of generatio equivoca or abiogenesis, the fundamental 
 significance of which is obvious, occupied the learned world 
 from Needham's time, 1745, to our own day. You know that 
 it is principally being fought out over putrefactive ferments, 
 vibrios and bacteria, but that it applies generally to all organised 
 ferments. The decision of these questions is of the utmost 
 importance to the pathology of digestion, and thereby justifies 
 a short account of them. The entire dispute between the 
 panspermists and heterogenists has always turned upon the 
 fact, that if one side brings forward experiments which prove 
 that under proper regulations no spontaneous development of 
 vibrios and bacteria takes place in a suitable nutritive fluid, 
 the other side maintains that in consequence of these regulations 
 the nutritive fluid has lost its nutritive qualities, and therefore 
 a spontaneous development of ferment is impossible; and, on 
 the other hand, if the others believe they have proved spontaneous 
 development, their opponents maintain that either the originally 
 present germs were not removed or made innocuous, or their 
 entrance during the experiment was not excluded. This is the 
 constantly repeated train of ideas in the works of Schroder, 
 Dusch, Schwann, Helmholtz, Wyman, Bastian, Huizinga, 
 Geschleidlen, and many others, who took their ideas from 
 the famous experiments of Guy Lussac, according to whom 
 the oxygen of the air was the cause of putrefaction. Pasteur 
 first, who in the year 1856 brought forward a series of pioneering 
 observations on ferments and fermentation, " qui ont fait cette 
 question presque la sienne ' (Guillaud), succeeded by his 
 numerous able researches in establishing, as it appears to us, 
 
24 LECTURES ON DIGESTION. [Lect. II. 
 
 the irrefragable proof of panspermism, the quintessence of 
 which is included in the following points, which were proved 
 by strict experiments :■ — 
 
 1. There are at all times in the atmospheric air germs present 
 which are necessary to the development of vibrios and bacteria, 
 but the quantity varies with the locality. In pure land air and 
 on the tops of mountains they are present, as Cohn, Burdon 
 Sanderson, and Rindfleisch ascertained, in smaller quantities than 
 in the impure air of towns. 2. The nutritive fluids do not, by the 
 manipulation which destroys the contained germs, lose the capa- 
 city to take up new germs, and to bear and nourish vibrios, when 
 unheated air is admitted to them. 3. TTie germs contained in 
 the air or the vibrios themselves are destroyed by the prolonged- 
 action of red heat, so that in suitable fluids they are no longer 
 capable of development, whilst they stand temperatures of 
 120° — 130° C. without damage. 4. In nutritive fluids free from 
 ferment, to which air is admitted, the same organic forms are 
 found in 24 — 48 hours as in open fluids, but an alcoholic fermen- 
 tation has never been established, although the possibility of this 
 on the part of the fluids is conceded, because the yeast "cells are 
 not present in the air in sufiicient abundance to cause fermenta- 
 tion in the short time allowed, but in those fluids which rapidly 
 undergo spontaneous fermentation (grape-juice, fruit sugar) they 
 adhere to the surfaces of the vessels used in their manufacture. 
 
 These are the fundamental observations from which the follow- 
 ing corollary may be drawn, which is of special interest for us 
 practitioners of medicine. If arterial blood, under the necessary 
 precautions, be introduced into a receptacle which was submitted 
 to glowing hot air, and to this blood glowing hot air be ad- 
 mitted, no putrefaction follows, an observation which demon- 
 strates before oar very eyes the untenability of the doctrine of a 
 spontaneous putrescence of the blood, the putrid fever of the old 
 writers, which played so great a part in humoral pathology, and 
 even now-a-days springs up here and there. The method of 
 these experiments is so simple and ingenious, that I must explain 
 it in one or two words. Imagine a T tube which is connected at 
 one end with a red-hot tube from a furnace, through which air 
 can come, and the other end with an air-pump, and the third 
 with a somewhat short tube in which is a solid piece of glass. 
 Each division may be shut oS" from the others by a stop-cock. 
 
THE GERM THEORY. 25 
 
 In the other opening of the short tube there is hermetically fixed 
 the finely drawn-out and sealed end of a retort, in which, before 
 sealing, the nutritive fluid * was exposed to the necessary tempera- 
 ture for destroying the germs. It is now clear that, with the aid 
 of the air-pump, first the space from the retort to the stop-cock, 
 which goes towards the iron tube, may be made airless and then 
 filled with glowing hot air, which by proper arrangement of the 
 stop-cocks and use of the pump may be at pleasure removed and 
 renewed, until we are sure that all unheated air has been driven 
 out. If now the hard piece of glass in the wide tube be allowed 
 to fall upon the point of the neck of the retort so as to break it, 
 the nutritive fluid will be brought into contact with the heated 
 air, and the result will be the absence of any putrefaction. The 
 variations of this experiment require no further explanation. 
 Here belong also the researches of Cazeneuve and Livon, who 
 found that the excised and tied bladder, if the urine had been 
 experimentally rendered alkaline during the life of the animal, 
 could be kept for a whole day at a temperature of 50° C, without 
 putrefection or the growth of fungi, provided that no air entered. 
 I myself have long since shown that we can keep pus from an 
 empyema at the body temperature for a week, if we receive it 
 with exclusion of air under recently purified mercury, while the 
 foul-smelling pus of a perityphlitic abscess, which was probably 
 infected from the intestine, very soon under the same conditions 
 was in a state of stinking putrefaction. We formerly said,! it 
 appears to us that these beautiful experiments of Pasteur's decide 
 once for all the doctrine of generatio equivoca, and with that the 
 question of the spontaneous appearance of organised ferments. 
 Since then the champions of spontaneous generation, so far as in 
 a few cases they have ventured forth, have sufiered mortal defeat 
 through the victories of bacteriology in other directions. The 
 botanists on the one side, and the biicteriologists under medical 
 discoverers like Klebs, and especially above all others Koch, on 
 the other side, have taught us the methods by which to preserve 
 nutrient bases for an unlimited timd,' and have furnished us with 
 an intimate knowledge of the conditions of the growth of "organ- 
 ised ferments." Wherever fermentative or putrefactive organ- 
 
 * The so-called Pasteur's fluid contains: aq. distil. 100"0, saoch. crystall. lO'O, 
 ammon. tart. 0"2 — 0'5, pot. phosph. or yeast ash O'l. 
 + In the first edition of these Lectures. Berlin, 1879, 
 
26 LECTURES ON DIGESTION. [Lect. II. 
 
 isms are present, ttey are introduced from without, although 
 their extraordinarily wide distribution and the consequent innu- 
 merable possibilities make a strict proof of their introduction 
 not always possible. All recent experimental data concur in 
 this, that without the entrance of organised ferments no putre- 
 faction takes place. The opposite experiments have proved to be 
 erroneous, and tip to the loresent time not a single imtrefactive 
 pi'ocess has been proved to occur without the intervention of living 
 cells — sp'outing or fissiparous fungi. 
 
 In the preceding lecture I have told you that one aspect of 
 fermentative action may be defined after A. Mayer, as that "their 
 amount stands in an extraordinarily small relation to the extent of 
 the resulting chemical processes." At the same time this relation 
 has its limits, and it must not be understood that with unlimited 
 growth on the one side there could be equivalent decrease on the 
 other. Theoretically, yes ! But practically not, because in all 
 careful studies of fermentative actions it has been proved that the 
 accumulated products of conversion after a certain time inhibit 
 the fermentation, and this happens in proportion to the rapidity 
 of action and quantity of the ferment. Moreover, within the time 
 that the ferment retains its unimpaired activity, it appears to be 
 a universal law that the amount of products of conversion is pro- 
 portionate to the amount of the ferment, and consequently the 
 ■time within which the conversion of a definite quantity of fermen- 
 table material takes place is inversely proportional to the 
 quantity of ferment employed (Roberts, Ellenberger, and Hof- 
 meister). 
 
 We have already spoken of a cardinal factor of fermentation, 
 namely, that it occurs by taking up water. On the intimate 
 nature and mode, how and in what part of the molecule it occurs, 
 the following important table from Hoppe-Seyler indicates. But, 
 above all, you will obtain from it an insight into the different 
 fermentations, so far as they interest us, and with its help you 
 will be able easily to discover your whereabouts in the future. 
 It may be observed that the following formula are in many 
 instances not exact, but only approximate expressions of the 
 changes that take place in fermentations. According to the 
 suggestions which were made by Nencki on the bases of the pro- 
 cesses which occur in the decomposition of albumen by caustic 
 potash, the processes of fermentation run their course in a much 
 
BIBLIOGRAPHY. 27 
 
 more complicated way than this table shows. The formation of 
 lactic acid out of grape sugar, for example, is only possible by 
 the taking up and giving oflf of water and the formation of a 
 non-existable intermediate jDroduct dioxypropionaldehyde (OH 2 
 (OH) — OH (OH) — OOH), and further by the assistance of water 
 and peroxide of hydrogen. 
 
 But we should gain nothing by pursuing this purely specu- 
 lative discussion on their construction, so that we pass it by. At 
 the same time the following formulae express not so much the 
 actual relations as an approximate illustration of them, so far as 
 it is possible to put together in a table all the concurrent reac- 
 tions of separate fermentations. Thus, for example, in the con- 
 version of starch there is formed maltose, a body nearly related 
 to grape sugar, with the formula C^ Hjj 0^ + H2 ; in alco- 
 holic fermentation glycerine and succinic acid are formed, as 
 well as traces of vinegar, as bye-products. But it is in accord- 
 ance with the best authorities not to introduce them in the 
 formulae. We have already spoken (p. 14, et seq.) of the other 
 factors, so that I may avoid their repetition, and can pass on now 
 to what is more strictly our subject. 
 
 Peocess of Feemkntation. 
 1. Convei'sion of anhydrides into hydrates. 
 
 p, ,. J Sfcarch or glycogen to dextrine and grape sugar. 
 
 ^ I 2 (C, H,„ 0,) + H, = Gs H,„ O5 + Ce H,^ O5 
 
 p of Pan < Starch to maltose and dextrine, 
 
 creas '- ^ ^^^ ^'» ^^'^ + Ha = C„ H,, 0„ + C, H,„ 0, 
 
 J , . J Cane sngar to IseTulose and grape sugar (dextrose), 
 
 inyertm | ^^^ ^^^ ^^^ + H, = C^ H,, 0, + C^ H„ 0, 
 
 ( Amygdalin to grape sugar, oil of bitter almonds. 
 
 Emulsin ) *^^» ^" ^0,, + 2 (H, 0) = 2 (C, H„ 0,) + C, H, + 
 
 J hydrocyanic acid. 
 
 (^ HON. 
 
 ?^'™ ,. ,rr . iAlbumen + n(H,0)= 
 Pancreatm (Trypsin) (. 
 
 Pepton 
 
 Leucin 
 
 Tyrosin 
 
 Asparaginic acid 
 
 G-lutamines, &c. 
 Pancreatic ferment, ( Tristearin to glycerine and stearic acid, 
 breaking up fats. I C„ H,„ 0, + 3 (H, 0) = C:, H^ 0,, + 3 (C,, H.^ OJ 
 
 Urea decomposition by f TJrea Carbonate of ammonia, 
 
 micrococcus ure». I CH^ N^ + 2 H^ = CO,, (NH,) 2 
 
28 
 
 LECTURES ON DIGESTION. [Lect. II. 
 
 C Lactic acid 
 Butyric acid fermenta-j 2 (G^ Hj O3) + 2 (H,, 0) = 
 tion by haoiUns subtiUs.i Butyric acid + carbonic acid and hydrogen. 
 ^ I C,H,0, + 2(C0,,H.j) + H, 
 
 f Hippuric acid to glycoooll and benzoic acid. 
 C„ H, NO, + H, O =C., H, NO., + C, H, O, 
 Putrefactive processes, | Taurocholic acid to tanrin and cholic acid, 
 the ferments of whioh<^ C„ H„ NSO, + H., O = C, H, NSO3 + C.,, H,, O^ 
 have not yet been iso- Cellulose to carbonic acid and marsh gas. 
 lated. n (C, H,„ O,) + n (H, 0) = 3n (CO.) + 3n (CH,) 
 
 V Albumen + n (H., O) to globulin, peptone, &c. 
 Leuoin and other Amidio acids 
 Tyrosin 
 
 Indol, Phenol, Scatol 
 Fatty acids 
 Carbonic acid 
 Ammonia 
 Sulphuretted hydrogen. 
 
 2. Conversion witli passage of oxygen from hydrogen to car- 
 bonic acid atoms. 
 
 Alcoholic fermentation. , 
 
 r Grape sugar to alcohol and carbonic acid. 
 "^«^"*- 1 C, H„ 0^ + 2 (H., 0) = 2 (C, Hs 0) + 2 (CO3 H,). 
 
 Bacterium laoticum f Milk sugar to grape sugar to lactic acid. 
 
 (Cohn) 1 C,, H,, 0„ + H, O = 2 (C^ H„ 0,) = 4 (C, H5 0;,). 
 
 Mucous or Mannite r Dextrose. Gum. Mannite. 
 
 fermentation by mi-] 15 (C„ H,., 0^) = 3 (C,., H.,, 0„) + 16 {G„ H,, 0„) + 
 croc, viscosus. (■ 3 (CO.,) + 3 (H.j O). 
 
 Pfeffer. Das Wesen und die Bedeutnng der Athmung in der Pflanze. Landwirth, 
 
 schaftl. Jahrbucher. Bd. vii. p. 805. 
 P. Bert. Comptes Eendus, 1873, Vols. Ixxvi. and Ixvii. Also his book, La 
 
 pression barom^trique. Paris, 1878. 
 Dumas. Quoted by Schiltzenberger, die Gahrnngserscheinungen. 
 Lechartier and Bellamy. De la fermentation des fruits. Compt. rend.. Vol. 
 
 Ixix. p. 466, and Vol. Ixxv. p. 1203. 
 Paschntin. Einige Versuohe ilber die buttersaure Giihrung. PflUger's Archiv. 
 
 Bd. vii. p. 352. 
 Hoppe-Seyler. Loo. cit. 
 M. Traube. Deber das Verhalten der Alkoholhef e in sauerstoffgasfreien Medium. 
 
 Berichte d. deutsch. chem. Gesellschaft, 1874, p. 885. 
 Hilfner. Ueber ungeformte Fermente und ihre Wirknngen. Journal f. praot. 
 
 Chemie. Bd. xx. p. 1. 
 Brefeld. Untersnchungen iiber Alkoholgilhrung. 1 und 11. Verhandlg. d. Wiirz- 
 
 burger phys. med. Gesellschaft, Bd. vii. 26 July, 1873, and 13 June, 1874. 
 Eeess. Botanische Untersnchungen iiber die Alkoholsgahrungspilze. Leipzig, 
 
 1870. 
 Guillaud. Les ferments figure's. Paris, 1876. 
 Nageli. Die niederen Pilze, &o. Munchen, 1877. 
 
BIBLIOGRAPHY. Zy 
 
 Pfeffer. Osmotisohe Untersuohungen. Leipzig, 1877. 
 
 Caseneuve and Livon. Eeoherohes exp. but la fermentation ammoniacale de 
 
 I'nrine. Eev. menanelle de Med., 1878. 
 C. A. Ewald. Untersuohungen zur Gasometrie der Transudate des Menschena. 
 
 I. Abth. Eeiohert u. du Boia-Eeymond's Arohiv., 1873, p. 687. 
 W. Eoberts. On the estimation of the amylolytio and proteolytic aotirity of 
 
 pancreatic extracts. Proe. Eoy. Soc, vol. xxxii., p. 14. 
 EUenberger and Hofmeister. ITeber die VerdauungssUfte und die Verdauung 
 
 des Pferdes. Arehiv. f. wias. u. prakt. Thierheilkunde. Bd. i. et aeq. 
 P. HUppe. TJeber die Zersetzung der Milch und die biologisohen Grundlagen der 
 
 Gahrungsphysiologie. Deutsche med. Woohenschr. 1884, p. 777. 
 A. Fitz. Ueber Spaltpilzgahrungen. Berichte d. chem. Gesellsch. xiii. p. 1188. 
 E. Buohner. Ueber den Einfluss des Saueratoffs auf Gahrnngen. Zeitschr. f. 
 
 physiolog. Chemie. Bd. ii. p. 330. 
 E. Pflilger. Die allgemeinen Lebenseracheinungeu. Eede zum Antritt. des 
 
 Eectorates. Bonn, 1889. 
 Pasteur. Comptes Eendus, 1. 1. and li. 
 
30 
 
 LECTURE III. 
 
 Gentlemen, — From tlie simple sac-like invagination of the 
 asteridea, into which the " moving ocean " drives the food of 
 the animal, up to the complicated gastro-intestinal system of 
 the ruminants, with their three stomachs, the intestinal tract 
 and its appendages fulfil the needs of each animal species in a 
 wonderful manner. This is strikingly expressed, amongst other 
 things, by the relation of its length to the length of the body. 
 It is, on easily understood grounds, largest in the ruminants, 
 as 16 — 20 : 1 (in the sheep 28:1); in thfe carnivora as 4:1, 
 and midway between these stands man with 6:1.* Swammerdam 
 has shown that the tadpole, which lives on plants, has an 
 intestinal canal about nine times the length of its body, whilst 
 in the frog, which lives on animal food, the relative length falls 
 to 2:1. Interesting, though probably without profound signi- 
 ficance, is the observation of Beneke, that the intestinal canal 
 in children is not greatly longer in proportion to the length 
 of their bodies than in adults. 
 
 That the digestive tube in the higher animals also is merely 
 an invagination of the surface of the body, is suggested by the 
 prolongation of the epithelium of the epidermis into its oral 
 and aboral openings; but it stops there, and there is another 
 kind of epithelial layer where the special work of digestion 
 begins. If, however, as we have already (Lecture I.) shown, 
 the intestinal tract is constructed on one and the same type 
 throughout all classes of the animal kingdom, the above-mentioned 
 appendages, which prepare the digestive juices (so far one can 
 regard the stomach as a sac-like appendage of the intestine), 
 are not so uniformly distributed. They are present equally 
 in all vertebrata, with the exception of the pancreas, which 
 is absent in many fishes; and this fact should have impressed 
 
 * But we nrnst remember that the length of a man is measured from his heels 
 to his vertex, while in most animals we measure from the end of the head to 
 extremity of the caudal vertebrae, so that we might get very different results if 
 a uniform plan were adopted. 
 
MASTICATION. 31 
 
 on our predecessors that a principal and fundamental distinction 
 between herbivora and carnivora, corresponding to the nature 
 of the digestible matter, does not exist. On the other hand, 
 stomach, liver, pancreas, &c., are absent, sometimes singly, 
 sometimes entirely, in the invertebrata, conditions which cannot 
 be gone into now, although it is extraordinarily interesting to 
 follow the gradual formation and development of these structures, 
 as the growing requirements of nutrition demand them. We 
 shall restrict ourselves to the vertebrata, and will keep well 
 within our prescribed limits, so that we shall pass over the 
 details of the topographical and coarse anatomy of the various 
 organs, and only concern ourselves with their functions. Yet 
 we shall have something to say of their minuter structure, so 
 far as this may be necessary to the understanding of their 
 function.* 
 
 Pood and drink are generally taken, apart from some 
 exceptional cases, by the mouth. We drink, that is, we bring 
 the narrow cleft of the mouth to the edge of the vessel and to 
 the surface of the contained fluid, and exercise a sucking action 
 with the lips and cheeks. We in this way draw the drink into 
 the cavity of the mouth and then transmit it by the act of swallow- 
 ing onwards, first into the back part of the mouth cavity (the 
 pharynx), and then through the oesophagus into the stomach. 
 Food, so far as it is not previously divided and comminuted, 
 is bitten or minced by the incisor and canine teeth, and ground 
 and torn up into finer particles by the molars, towards which 
 the portion of food lying on the back of the tongue is pressed 
 by that organ. This action, mastication, is performed by the 
 muscles connecting the upper and lower jaws, by pressing the 
 latter in a horizontal and vertical direction against the former. 
 The masseter and temporal muscles draw up the lower jaw 
 against the upper, the internal pterygoids draw it upwards and 
 forwards, the external pterygoids forwards, while it is drawn 
 downwards by the digastrics, the mylo- and genio-hyoids. 
 Finally, the buccinators force back between the teeth such 
 portions of food as escape laterally between the upper jaw and 
 the cheeks. 
 
 The teeth are the assistants of the stomach, whose work they 
 
 * See P. W. Knikenberg, Grnndzilge einer vergleiohenden Physiologie des 
 Verdatiimg. 1882, Heidelberg. Winter's Terlag. 
 
;J2 LECTURES ON DIGESTION. [Lect. HI. 
 
 facilitate or even render possible. Bad and defective teeth 
 have not only the consequence of making digestion more 
 difScult, as they insufficiently prepare the material, but they 
 occasion many pathological accidents, such as putrefactive 
 processes, which develop in the carious teeth, and are trans- 
 planted from the cavity of the mouth to the stomach. The 
 care and maintenance of the teeth is, therefore, a very important 
 factor of good digestion, too long neglected by us in Germany ; 
 and the expression of an English author, that the treatment 
 of stomach diseases begins with the teeth, has in it much that 
 is true. It is true that now-a-days we do generally take care 
 to have carious teeth stopped, defects replaced, and such faults 
 are not suiFered in the younger generation. But the proper 
 prophylaxis, that is, the careful purifying of the mouth by 
 washing it many times a day, and especially after meals, and 
 brushing the teeth with a disinfecting mouth-wash, is not yet 
 very common. 
 
 Pood during the act of mastication is saturated with the 
 secretion of the mouth, the mixed saliva, and coated and 
 lubricated by it. Mastication causes reflexly an active secretion 
 of the gland structures concerned. 
 
 We will begin with the Salivary Glands. 
 
 Of the four gland groups, the united secretions of which 
 formed the onixed saliva, we will first take the submaxillary 
 glands, not only because the classical investigations of 0. Ludwig 
 and CI. Bernard discovered in them an apparently inexhaustible 
 field of fruitful physiological investigations, but also because in 
 them the processes of glandular activity, kut i^o'xrjv, are most 
 ■instructively studied, and the fundamental data for the theories 
 of the secretion of glandular organs have been derived from 
 them. Do not be surprised, therefore, if we occupy an apparently 
 disproportionate amount of our time on the study of the sub- 
 maxillary glands. 
 
 The submaxillary glands belong to the type of mucous glands, 
 that is, they secrete a fluid rich in mucus but without diastatic 
 action, and they are distinguished thereby from another group 
 of glands, which were named " albumen glands" (serous glands), 
 by Heidenhain, whose secretion more resembles the composition 
 of blood serum, but contains a large amount of albumen and 
 above all, at least in many cases, a diastatic ferment. 
 
THE SALIVAHY GLANDS. 33 
 
 Both groups belong in essential features to the acinous, or as 
 they have been recently called, the compound tubular glands, 
 and in both the distribution of blood and lymph vessels and 
 their structural arrangements are on the same plan. The 
 blood vessels ramify in a delicate network over the acini, and 
 are separated by the alveolar wall from the lymph spaces, which 
 are more or less full, according to the physiological condition 
 of the gland, and the capillaries are thereby separated more 
 or less from the wall of the acinus. They unite in spaces 
 between the gland lobules, finally opening into the lymph 
 vessels of the hilus. The interacinous connective tissue offers 
 no special peculiarities. In its meshes are found lymph 
 corpuscles and Waldeyer's plasma cells. 
 
 The minute structure of these glands has been studied, 
 especially in the dog, rabbit, cat, calf, and sheep, and their, 
 anatomy is known completely. A number, mostly 5 — 10, of 
 epithelial cells group themselves round the commencement of 
 the excretory duct, which lies in the middle, and are sur- 
 rounded by a common capsule, the membrana propria. The 
 latter is a structureless membrane, stretched between peculiar 
 connective tissue-like cells with rib-like processes, so-called 
 basket cells (Henle, Boll), and cuts the cells off from one 
 another and so shapes the alveolus. Bach alveolus is attached 
 to the duct like a raspberry to its stalk ; the latter is covered 
 with a special very finely striated-looking epithelium (Pfliiger). 
 Under ordinary circumstances, as for instance when the animal 
 employed has not lost an unusual amount of saliva before the 
 gland was removed, the special gland-cells contain two zones, 
 best seen in alcohol preparations, less distinctly in fresh sections 
 — an outer granular layer, containing flattened nuclei, proto- 
 plasmic and lying against the membrana propria, and a glass- 
 like mucous inner zone, turned towards the commencement of 
 the excretory duct, which in extent surpasses the first. The 
 hyaline contents of these last may with certainty be proved to 
 be mucus, or probably an earlier stage of mucin, mucigen, by the 
 appropriate micro-chemical re-agents (cloudiness on adding 
 acetic acid, clearing again with strong mineral acids or weak 
 alkalies. According to Watney, hsematoxylin stains mucigen 
 but not mucin). The entire outer zone has its nuclei easily 
 stained with colouring agents (carmine, hsematoxylin, &c.) 
 
 3 
 
34 LECTURES ON DIGESTION. [Lect. in. 
 
 the inner remains unstained. In many alveoli, especially- 
 frequent in the gland of the sheep, much more rarely in the 
 dog, some of the cells are smaller than the others, and contain 
 only protoplasm. They lie close under the membrana propria, 
 and bend the other cells into a sickle-shape, so that Gianuzzi has 
 described these complexes of cells as "crescents" (halbmondchen). 
 Heidenhain believes that they represent an early stage of the 
 others. If the gland is irritated, either reflexly from the 
 mucous membrane of the mouth, or directly from the nerves 
 by electrical stimulation, or indirectly by pilocarpine injection, 
 so as to continue secreting for an hour or more, we find, as 
 Heidenhain discovered, a quite changed appearance in the gland 
 prepared in exactly the same way, and which moreover feels 
 harder than an unstimulated specimen even when fresh, but 
 especially after hardening in alcohol. The alveoli are all smaller, 
 the interalveolar connective tissue is more distinct. Nothing is 
 to be seen of the hyaline inner zone of cells ; they are filled with 
 brightly-stained protoplasm; the nucleus is pushed up to the 
 middle, is large and round ; the distinction between the " crescents" 
 and the rest of the alveolus has disappeared. While a stained 
 section of the unstimulated gland looks clear on account of the 
 preponderance of the unstained mucus, the sections of the 
 stimulated gland present a universal, vivid colouration from the 
 staining agent employed, as you may perceive in these two 
 preparations stained with hsematoxylin ; in short, there is such 
 an enormous difierence between the stimulated and unstimulated 
 gland, that it never could be guessed that both were derived 
 from the same organ. The passage from one to the other con- 
 dition may be observed in all the intermediate stages of the 
 gradual disappearance of the mucus and the recoil of the proto- 
 plasm. There can be no doubt that in the "mucous glands," 
 as well as in the " albumen glands," about to be described, the 
 protoplasm of the cells is converted by their function into the 
 specific secretion or a preliminary stage of it, and this is efiected 
 not at the moment of secretion but during the functional pause 
 of the organ, or as we should rather say, during the period of 
 its lessened activity. A complete cessation of secretion within 
 the cells in all these glands, so far as we know, never takes 
 place. 
 
 We can by no means admit, as the sequel will show, the 
 
FORMATION OF MUCUS. 35 
 
 earlier simple view, that the cells of the active gland merely 
 afford an outlet to a separated, and as such, previously formed 
 secretion. The function is rather the formation during secretion 
 from the cell contents of a definite specific secretion out of a 
 material prepared and stored up during the pauses in secretion. 
 The submaxillary gland converts mucigen into mucin, the 
 stomach propepsin into pepsin, the pancreas protrypsin into 
 trypsin, &c. In the " albumen glands " the cells are not de- 
 stroyed but have the power of self-regeneration. With respect 
 to the mucous glands, the fate of the cells has been for long 
 discussed and is still a subject of controversy. 
 
 According to Heidenhain, the original cells are completely 
 disorganised by their protoplasm becoming mucus, and in the 
 ."stimulated" gland we have before us only the young after- 
 growth of the " crescents " as a consequence of a trophic " nerve- 
 action." I formerly sought to prove that the cells persist and 
 only lose their mucus, and that one can obtain the appearance 
 of a stimulated gland without physiological stimulation by 
 withdrawing the mucus from the cells in another way, namely, 
 by treating these fresh sections with feebly ammoniacal carmine 
 solution. Heidenhain holds, however, that the resemblance of 
 preparations artificially deprived of mucus to the physiologically 
 exhausted gland is only apparent, and states that he and his 
 pupils, Lavdovski and Beyer, have directly observed (in the 
 sublingual gland) the disappearance of the mucous cells and their 
 formation from the parietal cells, while he refers to the analogy 
 of the processes in the so-called mucous cells of the external 
 skin or of the lower animals, the total mucous transformation 
 of which is recognised. Langley, on the basis of more recent 
 investigations, interprets the " young " cells of Heidenhain as 
 only old altered mucous cells, and does not admit that the 
 " crescents " disappear after prolonged secretion, but that they 
 only grow smaller and their nuclei more distinct. Kniippel was 
 able, at least in insects, to prove the destruction of the secreting 
 cells. After repeating my experiments, I can confirm the 
 observations first made by me in 1869, and I have the satis- 
 faction that such well-known microscopists as Ranvier, Bizzozero 
 Dewitz, and Stohr, have come to the same conclusion in other 
 ways. The question appears to me to have been much advanced 
 by a very interesting investigation of Arloing and Renaut, 
 
36 LECTURES ON DIGESTION. [Lect. IH. 
 
 based upon the elective staining properties of the cells. If 
 we stain the cells of an unstimulated gland hardened in osmic 
 acid and alcohol, by means of haematoxylin-eosin, the mucous 
 cells become pale blue, the parietal cells red, and the nuclei 
 dark violet. If the mucous cells of the stimulated gland are 
 destroyed and are replaced by the growth of the outer zone, it 
 must at least be possible to show by the staining that there is a 
 displacement in the arrangement of the cells. But this is not 
 the case. The mucous cells remain blue, though much diminished 
 in size ; the cells of the crescent are red, and Arloing and Kenaut 
 conclude therefrom " que les cellules muqueuses de la gland 
 sous-maxillaire ne se detruisent pas en fonctionnant." I must 
 leave these gentlemen the responsibility for their observation, 
 which I have not had the opportunity to confirm ; but I hold 
 the proposition as still correct with which eleven years ago I 
 ended these remarks in the first edition of this work : " The 
 destruction of individual cells and their restoration by an 
 immediate new formation during the relatively short period 
 of stimulation seems to me still doubtful." It should be 
 noticed that this proposition does not exclude the possibility 
 of the events described by Heidenhain taking place under 
 very excessive irritation. But so far as physiology enables 
 us to determine what takes place normally, it must be an 
 abnormal, that is in a certain sense a pathological condition 
 in which they can occur. I will only add that I had the 
 opportunity to investigate the salivary glands of a newly-born 
 puppy, which I show you here to-day, and which, as Heidenhain 
 has stated, have throughout the appearance of stimulated glands. 
 But this young animal had never formed any saliva to fill the 
 cells and displace their protoplasm. We shall return to this 
 point later on in speaking of the pancreas. 
 
 The secretion of the glands is excited through nerve filaments, 
 which run in part in the chorda tympani, in part in the sym- 
 pathetic, and influence the gland parenchyma, not continuously 
 but periodically. Their terminal branches have been traced by 
 Pfliiger, in a work published in 1869, up to the individual gland 
 cells ; he considers the salivary cell directly " as a swelling on 
 a medullated nerve," and "the gland cells as budding outgrowths 
 of the nerves," so that he in this fashion makes the most intimate 
 continuity between the nerve and cell. But none of the numerous 
 
SECRETION OF SALIVA. 37 
 
 followers of Pfliiger — and there is scarcely a histologist, says 
 Heidenhain, who has not had a longing to confirm his important 
 statements — has been in a position to confirm his descriptions ; 
 and Pfliiger appears to Heidenhain, in consequence, to be under 
 a delusion, his multipolar ganglion cells being merely the 
 anastomosing cells of the membrana propria. At all events, 
 the gland obeys the nerve as a good horse his rider, and nothing 
 is so surprising as to see how drop after drop flows from the 
 canula fastened in the excretory duct when one of the above 
 nerves is excited. By means of electricity the gland may be 
 made to secrete for hours, even for a whole day, if care is taken 
 by the use of a weak current and short pauses not to exhaust 
 the nerve and gland-parenchyma too early. It is known that 
 at the same time the temperature of the gland rises as much 
 as one-and-a-half degree of the Centigrade scale, that the blood 
 stream is hastened, that the venous blood escapes of an arterial 
 colour ; the pressure in the salivary duct when connected with 
 a manometer rises higher than the pressure in the gland artery, 
 and a pure, aqueous, slightly fibrin-forming secretion is poured 
 out. Only the first few drops of the secretion are made turbid 
 by epithelium and other elements of the tissues — products of 
 the irritation of the duct by the canula — as well as by crystals 
 of oxalate of lime, which are separated during the stagnation 
 in the duct. Pure saliva is free from morphological elements. 
 All this applies only to the secretion obtained by exciting the 
 chorda, the " chorda saliva." The " sympathetic saliva " is 
 thicker, jelly-like, much richer in mucus, is secreted in much 
 smaller quantity, and instead of widening there occurs a narrowing 
 of the vessels and slowing of the blood-stream. If acids or 
 alkalis are injected into the duct (Gianuzzi), or the animal is 
 poisoned by injecting atropin into the circulation (Heidenhain), 
 and the chorda be then stimulated, no secretion follows, but the 
 vessels become dilated, and red blood flows out of the divided 
 veins. (For this purpose a large dog requires 8 — 10 milli- 
 grammes of sulphate of atropia.) There must, therefore, be 
 two sets of fibres in the chorda, one quickening the circulation, 
 the other increasing secretion, or these latter fibres, or their 
 peripheral organs, the cells, may be paralysed by the said 
 injections. If, whilst the gland is under the influence of these 
 poisons, the sympathetic be stimulated, the ordinary sympathetic 
 
38 LECTURES ON DIGESTION. [Lect. IH. 
 
 secretion is obtained. The cells are therefore capable of acting, 
 and consequently the chorda nerves must be paralysed, and 
 thence it follows that the chorda and sympathetic fibres run 
 separately up to their terminations, and have different points 
 of connection with the gland cells. 
 
 The known antagonism between atropin and eserin suggests 
 the experiment to obviate the action of atropin poisoning by 
 injecting a requisite dose of extract of physostigma, and this 
 is, in fact, possible. If salivation is induced in an animal by 
 injection of pilocarpin, and then atropin be given, the flow of 
 saliva ceases. But after the injection of the requisite dose 
 of eserin the saliva begins again to flow from the canula 
 spontaneously, or after a small dose of pilocarpin. These 
 beautiful results of a series of experiments of Heidenhain's 
 are not only of importance for the salivary glands, but bear, 
 as it is scarcely necessary to insist upon, a universal significance. 
 It is being shown daily that apparently uniform nerve fibres 
 included in a common sheath possess not a uniform, but a very 
 diSerent action on the peripheral organs. I refer to the sciatic ; 
 and, by the above observations, Heidenhain has given us another 
 exceptionally clear instance of this condition. I shall be able to 
 show you the experiment, which is not difficult to perform, and 
 which I have already repeated many times. At the same time, 
 you can observe the salivating property of hydrochlorate of pilo- 
 carpin, which we can employ instead of the electric current. 
 The action of pilocarpin is paralysed by atropin, and this again 
 by eserin. 
 
 The constituents of the normal chorda saliva are approximately 
 as follow : the absolute figures cannot be given here or else- 
 where. 
 
 Water 996-04 
 
 Solid residue 3-96 — of which 
 
 Inorganic 2- 45 
 Organic 1-51 
 
 The organic constituents are : mucin, which is precipitated 
 as a whitish or fibrinous cloud when I let fall a drop of saliva 
 into a test-tube of water acidulated with acetic acid ; traces of 
 albumen, proved by a slight cloudiness on boiling, the xantho- 
 protein reaction (boiled with nitric acid it forms a beautiful orange 
 
COMPOSITION OF SALIVA. 39 
 
 red colour on adding ammonia), and the test with ferrocyanide 
 of potassium and acetic acid (a white precipitate). The sub- 
 maxillary saliva contains no diastatic ferment, as Heidenhain, 
 Griitzner, and Zweifel have proved (the last in newly-born 
 children). The saccharifying action repeatedly observed, by 
 myself and others after its action on starch for an hour or 
 more, is common to all albuminous bodies, which at a certain 
 temperature by decomposition form traces of ferment, and can- 
 not be regarded as a specific action of the secretion. The organic 
 constituents are chloride of sodium, chloride of potassium, 
 carbonate and phosphate of lime, phosphate of magnesia, and 
 phosphate of soda. The sympathetic saliva is richer in mucin; 
 poorer in water, and has, therefore, a much higher percentage 
 of organic constituents than the chorda saliva. The solid 
 constituents of the saliva diminish with the duration of the 
 stimulation — ^the organic more than the inorganic (Ludwig) — 
 and rise with the strength of the nerve irritation. Lastly, on 
 the condition that the water and inorganic salts increase pwri 
 passu with the strength of the stimulus, the organic constituents 
 increase at first more rapidly than the salts, but after the lapse 
 of a certain time they decrease as the gland gets exhausted. 
 If the stimulus is diminished, the quantity of salts in the 
 secretion begins to be diminished, and they decrease more 
 rapidly than the organic matter, so that their total excretion 
 becomes less than the latter ; in one case the organic constituents 
 are surpassed by the inorganic, and in the other case they are 
 more persistent; both quantities are to a certain degree inde- 
 pendent of one another, or, in other words, the quantity of 
 orgamic matter is not only conditioned by the strength and the 
 duration of the stimulus, but also hy the state of the gland 
 (Heidenhain). 
 
 These are very complicated conditions, which we want to 
 make as clear as possible, because, as we shall see directly, 
 they afibrd a very significant point of departure for the theory 
 of secretion. 
 
 Finally, there are gases in the saliva, free carbonic acid and 
 nitrogen. If the duct be tied, considerable cedema of the 
 gland occurs. The so-called " paralytic " saliva is the secretion 
 of saliva which sometimes occurs after section of the nerve, and 
 often continues for days, and which, discovered by Bernard, 
 
40 LECTURES ON DIGESTION. [Lect. HI. 
 
 has never been explained, either by himself or by his followers. 
 A young investigator in the realm of secretion, N. Langley 
 of Cambridge, holds the paralytic saliva to be a consequence 
 of an increased irritability of the central nervous system 
 consequent upon the operation, transmitted to the gland through 
 the sympathetic instead of through the divided chorda. It 
 is possible by anaesthesia and by inducing a condition of apnoea 
 to lower this irritability, and by causing dyspnoea to increase 
 it, so that the paralytic secretion can be increased or diminished 
 by the means described. 
 
 Beneke. Vorlaufige Mittheiliing iiber Lange und Oapacitelt des mensohl. 
 
 Darmkanals. Centrlbl. 1880, p. 216. 
 C. Ludwig. Mittheiltmg eines Gesetzes, welches die chemische ZueammenEetzung 
 
 des Unterkieferspeiohels beim Himde beberrsoht. Henle u. Pfeuffer's Ztsehrift. 
 
 f. rat. Med. N. F. Bd. i. 278, 1851. 
 E. Heidenhain. Studien des physiolog. Institutes zn Breslau. Hft. 4, 1868. 
 Pflliger. Die Speicheldriisen. Strieker's Hbob. der Gewebelehre, pp. 306 et seq. 
 Boll. Beitrage zur microskop. Anatomie der Driisen. Inang. Diss. Berlin, 1869. 
 CI. Bernard. Lefons sur les propridte's physiolog., &a., des liquides de I'organisme. 
 
 Paris, 1859. 
 
 L^fons de physiologie exp^rimentale. Vol. ii. Paris, 1856. 
 
 C. Ludwig. Neue Tersuohe iiber di« BeihUlfe der Nerven zur Speiohelsecretion. 
 
 Henle u. Pfeuffer's Ztsehrift. f. rat. Med. N. P. Bd. i. und iii. Series Bd. ii. 
 Gianuzzi. Von d»n Polgen, &c., fur die Absonderung des Speiohels. Beriohte 
 
 d. Sachs. Gesellschaft, 1865, p. 68. 
 C. Eckhard. Ueber die TJntersohiede des Trigeminus und Sympathicus Speiohels 
 
 der Glandula submaxiU. beim Hnnde. Eckhard's Beitrage zur Anatomie und 
 
 Physiologie, Bd. ii., 1860. 
 
 Kiihne. Lehrbuoh der physiolog. Chemie., 1868. 
 
 S. Wright. Der Speiohel in physiolog. diagnost. und therapeut. Beziehung, in 
 
 Eckstein's Handbibliothek des Auslandes. Wien, 1844. 
 Ewald. Beitrage zur Histologie und Physiologie der Speicheldrusen Inaue 
 
 Diss. Berlin, 1870. 
 
 Zweifel. Unters. uber d. Verdauungsapparat d. Neugeborenen. Berlin, 1874. 
 Grutzner. Notizen uber einige ungeformte Fermente des Saugethierorganismus 
 Pfluger's Archiv. Bd. xii. p. 285. 
 
 Ph. Stohr. TJeber Schleimdrusen. Sitzungsber. d. Wiirzburger nhvs med 
 Gesellschaft, 1884. "^ " 
 
 Arloing and Eenaut. Sur I'^tat des cellules glandulaires de la sons-maiiUaire aprSa 
 
 I'exoitation prolong^e de la corde du tympan. Comptes rendns. v. 88, p. 1366. 
 Dewitz. Uebers das verschiedene Aussehen der gereizten und ruhenden Druse 
 
 m den Zehenballen des Prosches. Biolog. Centralbl., 1883, No. 18. 
 Biizozero and Vassale. Ueber den Verbrauch der DrUsenzellen bei Saugethiere 
 
 Centralbl. f. d. med. Wissensoh., 1885, No. 4. 
 N. Langley. On the physiology of the salivary secretion. Part m. The 
 
 paralytic secretion of saliva. Journ. of Physiology, Vol. VI., p. 71—92 1885 
 Ph. Stohr. Lehrbuch der Histologie. Jena, 1889, p. 129 et seq. 
 
41 
 
 LBCTTJRB IV. 
 
 Gentlemen, — The remarkable discoveries to which the thorough 
 investigation of the submaxillary glands has led, demand a some- 
 what deeper acquaintance with an organ so specially interesting 
 for many reasons. The description of the other salivary glands 
 may, nay must, be short, because we know but little about them. 
 
 The parotid is absent in birds, because it is the masticatory 
 gland /car' e^o^nv, and grows in the animal series in proportion 
 to the development of the masticatory apparatus. Its histological 
 conditions are very similar to those of the submaxillary, but there 
 is no mucus in its cells. They consist of a clear ground substance 
 with a granular protoplasm sparingly distributed in the form of 
 a reticulum (Klein) ; their angular mesially placed nuclei take 
 up colouring matter readily, while the rest of the cell is only 
 slightly stained. Here, as before, a change in the microscopical 
 structure occurs on stimulating the nerve, with this difference, 
 that it is brought about, not by irritating the cerebral nerves, 
 but the sympathetic. The cells shrink, become very cloudy; 
 their protoplasm is better stained by carmine ; the round, many- 
 nucleolated nuclei become very distinct. This apparent difference 
 of nerve action in the submaxillary on the one hand and the 
 parotid on the other will in truth prove to be an analogy, so 
 soon as we have shown more completely the influence of the 
 nerves on the glands. The special glandular nerve is the 
 auriculo-temporalis, which unites with the small superficial 
 petrosal nerve at the otic ganglion ; the latter is connected with 
 the glossopharyngeal through the ramus tympanicus (N. Jacob- 
 soniij, and so conveys reflexes from the cavity of the mouth to 
 the gland. Heidenhain, whom we have again to thank for our 
 exact knowledge of details, stimulated the nerve from the tym- 
 panum. Moreover, the gland may be stimulated from the 
 sympathetic. In this case also the circulatory conditions are, 
 as in the submaxillary, dilatation of vessels and quickening of the 
 blood-stream on stimulating the cerebral nerve ; with narrowing 
 
42 LECTURES ON DIGESTION. [Lect. IV. 
 
 of the vessels and slowing of the blood-stream on stimulating 
 the sympathetic. Here also the pressure (118 m.m. mercury) 
 of the secretion in the duct may be made by continuous stimu- 
 lation much higher than the blood pressure. Moreover, there is. 
 in this gland a notable relation between the irritation of the 
 sympathetic and cerebral nerves. The irritation of Jacobson's 
 nerve only, for instance, gives an aqueous secretion free from 
 mucus, which contains a little albumen, paraglobulin, a diastatic 
 ferment, and the usual salts. The total of solid constituents in 
 this secretion is small, and of these the organic are less than 
 the inorganic. The irritation of the sympathetic is followed 
 generally by no secretion. But if the nerve of Jacobson and the 
 sympathetic are stimulated at the same time by two electrodes, 
 the secretion not only becomes richer in solid constituents, but 
 the relations between organic and inorganic are so upset that 
 the organic preponderates. For instance : 
 
 Solids. 
 
 Salts. 
 
 Organ, matter. 
 
 N. Jacobs, alone =0-56 
 
 0-31 
 
 0-24 
 
 N. Jacobs. + sympathet.^2'42 
 
 0-36 
 
 * 2-06 
 
 This suggests that the basis of this relation may be sought 
 for in the contracting effect of the sympathetic on the vessels. 
 But apart from the fapt that the quantity of salts in both cases 
 is approximately equal, that during simultaneous stimulus of 
 both nerves being rather the greater, this idea is directly dis- 
 proved by the observation that tying the carotid has no influence 
 on the experiment, although this would produce much greater 
 interference with the circulation than stimulation of the sympa- 
 thetic. We must also admit that the cerebral nerve presides 
 mainly over the excretion of water and salts, the sympathetic 
 governing the passage of organic matter into the secretion by 
 the formation of soluble substances in the cells. When we learn, 
 too, that similar changes in the contents of the secretion, in salts 
 and organic constituents, follow the duration and intensity of 
 the secretion as in the submaxillary, and that the contents of 
 the secretion in organic matter stand in no direct relation to 
 the quantity of water which the gland secretes, we cannot avoid 
 the conclusion that the sympathetic nerve exerts a specific 
 " trophic " influence on the gland cells. The nerve of Jacobson 
 governs mainly the separation of water, while the sympathetic 
 
SECRETING AND TROPHIC NERVE FIBRES. 43 
 
 presides over the formation of the specific elements of the secre- 
 tion. For the same reasons we were obliged to admit the 
 existence of two kinds of nerve fibres in the chorda, water- 
 secreting and mucus-secreting nerves, only they ran together in 
 one nerve sheath, while they go separately to the parotid. This 
 explains why the change in microscopic structure, which consists 
 chiefly in the changes in the organic gland substance, in one case 
 is brought about by stimulus of the sympathetic, in the other of 
 the chorda. If I first irritate the cervical sympathetic of this 
 rabbit with a canula placed in Stenson's duct according to 
 BLeidenhain's method, until I have obtained about 1 cm. of 
 secretion, and then invoke the cerebral nerves by injecting 
 pilocarpine into the veins, and collect the same quantity of 
 secretion, you see that the sympathetic secretion becomes a jelly- 
 like coagulum by heating, while the cerebral secretion becomes 
 only feebly turbid, although both looked equally clear before, 
 a proof of the richness of the sympathetic secretion in albumen. 
 From the above data we may derive the fundamental and signi- 
 ficant information that in these organs, and probably in all 
 similar glands, there are two sorts of nerve fibres possessing the 
 povjer of controlling secretion; these are secreting and trophic 
 nerve fibres running in the sa/me sheaths or separrately. The 
 former influence the circulation of the glands and effect the 
 secretion of water, salts, and small quantities of albumen. 
 The latter cause the secretion of the specific secretion, namely, 
 greater quantities of albumen, mucus, and ferment; indeed, 
 according to EUenberger and Hofmeister, the parotid secretion 
 contains more ferment than that of any other salivary gland. 
 
 It might appear, as indeed we stated in the second edition of 
 this work, that the mixed secretion was compounded in a definite 
 and satisfactory manner. 
 
 But Langley's recent observations have shown, as we may say, 
 unfortunately, that the relations are not nearly so clear as, accord- 
 ing to the original observations of Heidenhain, they seemed to be. 
 
 The English physiologist has clearly proved the inhibiting 
 influence of atropine injection on the secretion of the chorda 
 . saliva. But he has also studied the composition of the product 
 of bilateral stimulation of the sympathetic and chorda after 
 atropine poisoning had taken place. He found no great difference 
 from that of simple stimulation of the sympathetic, but on 
 
44 LECTURES ON DIGESTION. [Lect. IV. 
 
 investigating the secretion at other times under complex con- 
 ditions, as, for example, under different intensities of electrical 
 stimulation, after dyspnoea, compression of the aorta, venesection, 
 intra-venous injection of salt solution, &c., he came to the con- 
 clusion that the secretion is influenced variously under varying 
 conditions so far as concerns each of the three factors of which 
 it is composed, viz., water, salts, and organic matter. Conse- 
 quently we must distinguish not only two but three kinds of 
 secretory nerves, presiding respectively over water, organic 
 matter, and salts. 
 
 Langley thinks it is not necessary to accept such a complicated 
 and quite hypothetical mechanism, but he believes, basing his 
 b^Jief on the facts already stated, that the chorda after atropine 
 poisoning is paralysed in its secretory and trophic (hypothetical) 
 fibres, without doing violence to the facts, and consistently with 
 the far simpler hypothesis that only one hind of nerve fibre exists, 
 which exhibits different functions according to the changing 
 condition of the gland cells. 
 
 In man, a fine silver canula may be easily introduced, as I 
 show you here, into Stenson's duct, and a copious secretion takes 
 place, chiefly by reflex action. This secretion is alkaline, but, 
 according tcAstaschewsky and Mossier, with moderate secretion, 
 or when fasting it is feebly acid, free from mucin, and has a 
 diastatic action. In diabetics, though not invariably, it contains 
 Sugar, which is sometimes so abundant that its presence can be 
 proved by fermentation, reduction, and polarisation. 
 
 We know little about the sublingual glcmd, which is formed on 
 a very similar type to the submaxillary. It f&rnishes a secretion 
 similar to but more viscid than the last, which may contain as 
 much as 2-7 per cent, of solids, and is controlled by nerves which 
 run in the trunks of the chorda and sympathetic. We owe our 
 principal knowledge on this subject to some researches carried 
 out by Beyer in Heidenhain's laboratory, in which he tried 
 to prove that on strong stimulation the destroyed mucous cells 
 were replaced by a growth from the parietal cells, and for that 
 purpose the whole of the acini are filled with small highly 
 granular cells, but on moderate stimulation as well the destruc- 
 tion of the mucous cells arid the preformation of the new 
 replacing cells from the parietal cells may be followed. I refer 
 with respect to these relations to the descriptions already given 
 
BUCCAL AND LABIAL GLANDS. 45 
 
 (Lecture III., p. 34, et seq.), and especially to the work of 
 Stohr, " Ueber Schleimdriisen," for as they are much the same 
 in the parotid as in the sublingual we may conveniently abstain 
 from a detailed recapitulation. 
 
 The secretion of the buccal and labial glamds, likewise acinous 
 glands, may be obtained pure only after tying all the other ducts. 
 But the significance of such an experiment does not repay the 
 trouble involved, as the difference between the mixed oral saliva 
 and the secretions of the particular glands already described, 
 shows that the glandulee buccales et labiales separate a mucous 
 secretion very like that of the other glands. The product of all 
 the secretions poured out into the oral cavity forms the mixed or 
 oral saliva, the origin of which from various sources has been 
 already referred to. It falls from out of the cavity of the cleansed 
 opened and somewhat lowered mouth, sometimes in clear drops, 
 sometimes drawing long threads of mucus after it, according as 
 it is derived more from the mucous or the albumen fluids of the 
 oral cavity. 
 
 Its composition, according to Hammerbacher, is : — 
 
 Water 994-203 
 
 Solids 5-797 
 
 containing — 
 
 Epithelium and muein 2-20 
 
 Ptyalin and albumen 1-40 
 
 Inorganic salts 2-21 
 
 Potassium sulpho-cyanide 0-04 
 
 Its sp. gr. is from 1004 — ^1009, but these limits may be trans- 
 gressed in both directions ; according to Wright, a specific gravity 
 of 1017 was found in a case of exclusive meat diet. 
 
 The reaction is ordiaarily feebly alkaline during or soon after 
 eating, but it may often be neutral to litmus paper, as I have 
 often shown in fresh human saliva ; during fasting and in many 
 pathological conditions, e.g., in fever and in diabetes, it is at 
 times acid. This depends upon an acid fermentation of matters 
 present in the mouth at the same time, or perhaps upon the 
 above-mentioned property of the parotid saliva to become acid 
 under certain conditions. A remarkable but not constant 
 constituent of mixed human saliva is sulpho-cyanide of potassium, 
 an alkaline compound of sulpho-cyanic acid, ONSH, which 
 
46 LECTUEES ON DIGESTION. [Lect. IV. 
 
 may be recognised by its red colouration with ferric chloride, and 
 appears to be especially present in the parotid secretion. Why 
 this sulpho-cyanide of potassium is sometimes present and some- 
 times absent, and in what relation it stands to pathological 
 processes, we are ignorant. Its amount apparently varies, but 
 seems to average about 0-014 per cent. (J. Munk). Formerly 
 this sulpho-cyanide, the presence of which was quite unintelligible, 
 was regarded as a decomposition product, probably, according to 
 Pettenkofer, formed from urea and potassium sulphide. Since 
 what we have learnt of the destruction of albumen in the 
 organism has made the formation of hydro-cyanic acid in the 
 highest degree probable, the presence of sulpho-cyanic acid has 
 become more intelligible, though it still remains very extra- 
 ordinary, according to BUenberger and Hofmeister, that the 
 saliva of the horse, ox, sheep, and pig contains none. Inci- 
 dentally I may mention the morphological elements of the 
 mixed saliva, namely, salivary corpuscles distinguished by their 
 active molecular movements, and abraded epithelial scales. 
 Pure saliva, according to the above-named investigator, is free 
 from micro-organisms, although they are found in the mixed 
 saliva of the oral cavity ; perhaps this is why the mixed saliva 
 has a stronger amylolytic action than any of the component 
 salivas separately. Finally, a fact is stated by many authors 
 which may be easily verified, that an important saccharifying 
 agency is derived from the leucocytes which find their way 
 into the fluids of the mouth from the follicles of the tongue and 
 tonsils, though it may be that without the assistance of micro- 
 organisms they would be powerless. 
 
 But this amylolytic action which is brought about by the 
 diastatic enzyme of the saliva, the so-called ptyalin, is of great 
 significance for the mouth and stomach digestion, and deserves a 
 closer description. We have not succeeded in obtaining pure 
 ptyalin. As is so frequently the case in fermentation processes, 
 we conclude from the known action of the secretion the presence 
 of a ferment to which we have given a name, but have not yet 
 obtained in all its purity. It is Cohnheim's merit to have first 
 obtained a diastatic and approximately pure preparation from 
 human saliva. A most simply performed experiment teaches 
 how rapidly and energetically mixed saliva converts starch into 
 maltose and sugar. Solera found traces of " grape sugar " twelve 
 
DIASTATIC ACTION OF SALIVA. 47 
 
 seconds after the commencement of the reaction, but probably 
 the process begins even more quickly. I have treated a solution 
 of starch with saliva and sufficient hydrochloric acid to inhibit 
 the diastatic action of the ptyalin, warmed it to 37°, then added 
 rapidly a previously measured neutralising amount of alkali, 
 and at once boiled some with Fehling. A decided reduction took 
 place. Yet a considerable time is always needed, varying 
 according to the relations between the saliva and the amount of 
 starch, at the temperature of the body always many hours, 
 before all traces of starch have disappeared from such a mixture. 
 "The starch is first converted into a soluble form, then into the J 
 intermediate products, ac*roodextrine and erythrodextrine, two n, . 
 bodies nearly related to starch, finally into a kind of sugar called / 
 maltose, as well as small quantities, about 1 per cent. (Mus- 
 culus, V. Mering) of grape sugar, a process which, according to 
 Paschutin, takes place most rapidly in boiled starch paste at 
 38° — 41° C, and according to the observations of E. Pfeiffer and 
 O. Nasse, by adding sodium chloride. This may be increased to 
 a maximum of 3'9 per cent., while by sodium carbonate it is 
 ■diminished. In a 2 per cent, solution of boiled starch, which 
 had remained thirty minutes in the fasting stomach of a healthy 
 person, I found only various dextrines and maltose, but no trace 
 of grape sugar. 
 
 Simply as we have given the process of converting starch into 
 sugar in the table at the end of Lecture II., it is not really so, 
 the processes in question taking place not successively, but in part 
 at the same time ; still we may regard the table as expressing 
 the truth in a convenient form. We know, too, that the old 
 view that starch is changed into sugar by the action of the saliva, 
 is so far erroneous that grape sugar is only present in traces, as 
 opposed to the formation of dextrine and maltose. But this is 
 not of great importance for the question of digestion, as the 
 important fact is the change of insoluble into soluble Ja pircr - 
 -« ag b o as. Mixed saliva changes starch into sugar not only in ''^ ' 
 alkaline and neutral, but also in acid solutions, if the acidity 
 does not exceed a certain point, which is for hydrochloric acid 
 between 0-01 per cent, and 0-025 per cent., and for the organic acids 
 is distinctly higher, up to 3 per cent. On the other hand, a very 
 small amount of acid, not exceeding 0"0001 to 0-0006 per cent, 
 •of free HCl. according to Chittenden, increases the activity of 
 
48 LECTURES ON DIGESTION. [Lect. IV. 
 
 ptyalin. The food passes through the mouth so quickly, that 
 there can be scarcely any question of the occurrence there of an 
 extensive chemical action, and besides the greater part of the 
 saliva is swallowed ; so with respect to the special evolution of 
 its diastatic function, it signifies very much how the relations 
 shape themselves in the stomach, to which we shall return in 
 the proper place. Ellenberger and Hofmeister have observed in 
 the horse that the saliva first secreted converts starch strongly, 
 the latter does so feebly or not at all, so that there must be a 
 previous preparation of ferment in the gland during the intervals 
 of secretion, as it evidently cannot be formed -pa/ri passii with 
 the demand. Ptyalin appears to possess, like other ferments, a 
 certain power of resistance to the influence of various digestive 
 juices and processes of tissue metamorphosis, so that it may be 
 transported to the kidneys and excreted in the urine. Cohnheim 
 discovered a diastatic ferment in the urine ; Grutzsser, Bolovt- 
 schiner, and others have further followed the passage of ferments 
 into the urine, and shown that the reducing power of the urine 
 after the addition of starch is strongest after meals, while the 
 urine after fasting passed in the morning contains only small 
 quantities. It therefore remains a question whether in truth 
 we have to do with a diastatic ferment, ptyalin, or whether in 
 urine, and other transudates of the body, substances are present 
 which convert the starch into reducing substances but not into 
 sugar, and should not be described properly as ptyalin. The 
 earlier investigations are not sufliciently definite, and Brensing 
 could not prove, on careful experimentation under fixed conditions, 
 that there was a true sugar formation from starch either in urine 
 or in its alcoholic precipitate product. The starch disappeared, 
 reducing substances made their appearance, but no sugar. 
 
 Like all alkaline fluids, the saliva, that is, mucous mixed saliva, 
 forms with rancid fats (that is, fats which contain some fatty 
 ' acids) beautiful emulsions on shaking, better, according to Ellen- 
 berger and Hofmeister, than can be obtained with pig's or sheep's 
 bile. A second very important property of the saliva is to lubri- 
 cate the morsels of food. The following observation of 01. 
 Bernard's, demonstrating this very clearly, is little known and 
 is worth relating. The oesophagus of a horse was opened, and 
 
 boli of moist oats were given by the mouth, which every 1 li 
 
 seconds came out of the opening, so that in nine minutes 500 
 
SECRETION OF SALIVA. 49 
 
 grms. had passed. But wten the parotid ducts were cut, the 
 parotid secretion, and therewith the chief part of the saliva, 
 being made to flow externally, the boli appeared only every 
 1 — 2^ minutes — in 25 minutes only 360 grms., which gives a 
 difference per minute of 41 "1 grms. At the same time it was 
 noticed that during drinking, the secretion of the parotid (and 
 probably also of the other glands) ceased entirely. Of course 
 the food is mixed with a greater amount of saliva in proportion 
 as it is rough and dry, so that EUenberger and Hofineister found 
 in the horse that double the quantity was secreted for oats, and 
 four times as much for hay, as compared with half the weight of 
 damp grass. In accordance with this, or in consequence if you 
 like, is the fact that the salivary glands throughout the animal 
 kingdom are feebly developed in proportion to the wateriness of 
 the food of the animal, be it, that the water is taken in or with 
 the food (aquatic animals). 
 
 Tuczek estimated by a special method how much saliva was 
 taken up by a well-masticated and afterwards expectorated morsel 
 of food, and found, as was to be expected a priori, that the poorer 
 the food was in water the more saliva was secreted. In this way 
 there were secreted daily, with black bread 545 grms., with 
 white bread 698, with mixed diet 476, with bread and potatoes 
 659, with highly albuminous diet 773 grms. of saliva. The 
 quantity of saliva for 24 hours is estimated by Bidder and 
 Schmidt to be in man 1,500 grms., but as has just been shown 
 there must be great variations according to the quantity and 
 quality of the food. Both sides of the oral cavity do not share 
 equally in this work of secretion. Pfliiger found that a third 
 more was secreted on the masticating side than on the other. 
 The secretion of saliva takes place reflexly through the glosso- 
 pharyngeal and lingual nerves, the food exercising the necessary 
 mechanical, thermal, or chemical stimulus. The reflex centre is 
 in the nucleus of the facial nerve on the meduUa oblongata, and 
 a cerebral centre exists in the region of the crucial sulcus (Eulen- 
 burg and Landois and others) which sends fibres through the 
 internal capsule to the spinal centre. Bechterew saw, after the 
 application of a feeble faradic current to the superior anterior 
 part of the fissure of Sylvius, a copious Secretion of saliva. More- 
 over, the stimulus to the secretion of saliva which follows certain 
 odours or even psychical impressions, is reflex, and likewise, in 
 
 4 
 
50 LECTURES ON DIGESTION. [Lect. IV. 
 
 part, through the trigeminus. The secretion follows, as we 
 have seen, immediately upon the stimulus, and if Schofield saw, 
 in a parotid fistula, secretion begin first a minute and a half after 
 eating, it is probable that there was a pathological cause for this 
 protraction. If I pass a fine canula, as above described, into 
 Steno's duct, a few seconds after the inhalation of ether vapour 
 the first drops flow from the canula. In the same way, as 
 Schofield states, by pepper and salt, chloroform, ethereal oils, 
 acids, and the like, the flow of saliva may be excited from the 
 gastric mucous membrane; indeed even from distant nerves, 
 such as the sciatic, we may induce secretion of the submaxillary 
 glands, and it is no uncommon phenomenon to observe increased 
 salivation from intestinal worms. Injections of pilocarpine, as 
 Ellenberger and Hofineister state, make the secretion watery and 
 impair its diastatic action. 
 
 What influence the suppression of the entire salivary secre- 
 tion has on the general health cannot be stated, because such 
 cases, with the exception of the local and transient diminution 
 of saliva in fever, in many cases of poisoning, &c., are not 
 known. Undoubtedly we sometimes meet with neurasthenic 
 persons whose chief complaint is of " unbearable dryness of the 
 mouth," but in such cases the secretion of saliva is by no means 
 suppressed, it is only diminished. Zweifel has found the dias- 
 tatic action of the parotid unchanged in the diseases of children. 
 The loss of saliva through fistulous openings does not appear to 
 have any particular consequences, although an English author, 
 Wright, who collected for purposes of observation 250 grms. of 
 his saliva in one week, lost 11 pounds weight (?). 
 
 On the other hand, the pathological increase in the secretion 
 of saliva does not permit its consequences to be distinguished 
 from those of the original afiection, but if we may judge from 
 the cases of ptyalism in hysteria, paralysis, &c., it may continue 
 for a long time without injury to the health ; on the other hand, 
 where the copiously-secreted saliva is swallowed and the stomach 
 digestion checked, digestive disturbances with their consequences 
 may occur. Finally, as a curiosity, may be mentioned the cases 
 of intermittent sialorrhcea, which, according to Eayer, are de- 
 scribed as recurring about every 30 — 50 days. From the phos- 
 phate and carbonate of lime in the saliva, which become partly 
 decomposed and combined with organic matter (mucin, albumen 
 
PHYSICAL CONDITIONS OF SECRETION. 51 
 
 fungi), arises the formation of salivary calculus, and tke plugging 
 of the salivary duct, with its consequences. 
 
 I cannot leave the subject of the salivary glands without re- 
 ferring to a view which Heidenhain has expressed with reference 
 to an old view of Hering's on the process of secretion. When 
 you remember the remarkable condition, that the pressure in 
 •the salivary duct is higher than the blood pressure ; when you 
 think of the fact that the poisoned cells of the submaxillary 
 gland stimulated from the chorda, in spite of the quickened 
 circulation, do not secrete, while there is neither oedema of the 
 gland nor increased flow of lymph, you will agree that the blood 
 pressure cannot explain the process of secretion, and that the 
 immediate cause must lie in the cells themselves, and not in the 
 stimulating influence of the blood. We may fully admit that 
 the circulation is only concerned so far that it delivers the 
 raw material, and meets an increased demand by an increased 
 rapidity of the current. Hering held secretion in the salivary 
 glands to be a process similar to the osmotic processes in plants, 
 having its origin in the capacity of mucin for taking up water. 
 He thus explained the fact that the salivary pressure is higher 
 than the blood pressure, because it is known that extraordinarily 
 high hydrostatic pressures are produced by osmotic actions. 
 But this is refuted, amongst other things, by the circumstance 
 that, as we have seen, in the parotid secretion, which is free from 
 mucin, a similar high pressure occurs. One must ascribe this 
 capacity of imbibition not only to the mucin, but also to the 
 entire glandular protoplasm, which absorbs water out of the 
 lymph vessels and blood in proportion to its hypothetical imbib- 
 ing capacity, so that once for all the cell contents stand under 
 a higher pressure than the blood. But these to a certain extent 
 compressed cell contents cannot flow out towards the duct before 
 the stimulus of the glandular nerves indicates that the ordinary 
 opposing forces are removed. Whether one should attribute 
 this, with Heidenhain, to a molecular arrangement, or imagine 
 a thermal influence which only concerns a part of the cell, -and 
 in this way permits a definitely directed osmotic current, re- 
 mains uncertain. In short, this explanation concerns only the 
 water and salts. The understanding of these processes is 
 assisted by the observations of Strieker, if they should prove true, 
 that the secretion of the cutaneous glands of frogs results from an 
 
52 LECTURES ON DIGESTION. [Lect. TV. 
 
 active contraction of the cells. The organic matter, we have 
 seen, is in a measure independent of the quantity of water 
 secreted, and its quantity increases with the stimulus. Here 
 comes in a peculiar function of the cell contents in the production 
 of the specific elements of the secretion. Perhaps the following 
 factor finds its place here, in addition to the so-called trophic 
 nerve stimulus: Kiihne and Lea have proved directly, in the 
 case of the pancreas, that all parts of a secreting gland are not 
 functionally active at the same time. Pathological facts, for 
 example in the kidneys, show that all parts of a gland are not 
 at all times equally active in secreting. If one part of the gland 
 cells is active longer than the other, and consequently is in 
 another stage of its work, perhaps it becomes early very ex- 
 hausted, and thus differences can arise in the combined secretion 
 during the different phases of the stimulus, which would explain 
 Heidenhain's facts. 
 
 Similar remarks of a general nature upon the process of 
 glandular functions which we have brought forward with refer- 
 ence to the salivary glands, are applicable to the other glandular 
 organs — for example, the gastric glands, the pancreas, Brunner's 
 glands, &c. They gain, therefore, a general significance for the 
 comprehension of these mysterious and wonderful secreting pro- 
 cesses, so that equipped with these views we need not return to 
 this question. 
 
 Astaaohawaky. Eeaotion des Parotisspeiohel bei gesimden Mensohen. CentralbL 
 
 f. d. Med. Wiaa. 1878, 257. 
 Beyer. Die Grlandula Sublingualis. Brealan, 1879. 
 Cohnheim. Zur Kenntniss der Znoker-bildendeu Permente. Tirohow's Arohiv. 
 
 Bd. xxviii. 241. 
 
 Pasohutin. Binige Yersuolie iiber Verdauungsprooesae. Centralbl. f. d med 
 
 Wiaa. 1870, 577. 
 CI. Bernard. Lea liquides de I'organiame. Paris, 1859. 
 Tuczek. Ueber die vom Mensohen wahrend des Kauens abgeaonderten Speichel- 
 
 mengen. Ztachrft. f. Biologie. Bd. xii. 534. 
 
 Ordenatein, quoted by TJhle and Wagner. Hdboli. d. allg. Pathologie Leinziff 
 1874,798. ^ ^' 
 
 Hering. Ueber die Uraaoben des boher Abaonderungsdruok in der Glandula 
 snbmaxillaris. Weiner Sitzgaber. math.-naturw. Lebre. Bd. Ixvi. 
 
 Heidenbain. Ueber seoretoriaohe und trophisobe Driiaennerven. PflUger's 
 Arcbiv. Bd. xvii. p. 1. 
 
 "Kilbne und Lea. Ueber die Abaonderung des Pankreas. Verbandl. d. naturhiat- 
 med. Vereins zu Heidelberg. Bd. i. Hft. 5. 
 
BIBLIOGRAPHY. 53 
 
 Ph. Stflhr. Ueber Sohleimdrusen. Sitztmgsberioht d. Wurzburg. phys. med. 
 
 Gesellsoh. 1884. 
 MuBoulus and v. Mering. Ueber die Unwandlimg von Starke nnd Glycogen 
 
 duroh Diastase, Speiohel tmdLaljfemiente. Zeitschr. f . pliySiol. Chemie. v. p. 403. 
 Sohofield. Observations on the secretion of saliva in a case of parotid fistnla. 
 
 St. Earth. Hoep. Eep., 1880, p. 147. 
 Solera. Nuove rioerche snlla attivita chcmica-fisiologica della saliva nmana. 
 
 Pavia, 1878, refer. Centrlbl., 1879, p. 231. 
 Strieker. Wiener med. Jahrblicher, 1883. 
 C. A. Ewald. Tageblatt der natnrforsoherversammliing zu Strassburg, i. E. 
 
 1885. 
 Chittenden. Studies from the Laboratory of Yale College ; Diastatio action of 
 
 saliva. New Haven, 1885. 
 Bossbach. Ueber die physiologische Bedeutung der aus den Tonsillen nnd 
 
 Zungenbalgdrilsen auswandemden Lenkocyten. Verhandl. d. Cong. f. innere 
 
 med., 1887, p. 208. 
 Chittenden and H. Smith. The diastatio action of saliva as modified by various 
 
 conditions. Tale College, 1885. 
 Gehrig. Ueber Permente im Ham. PflUger's Aroh. Bd. 28, p. 35. 
 Holovtschiner. Ueber Ptyalin nnd Labferment im mensehliohen Ham. Virchow's 
 
 Arch. Bd. 107, p. 186. 
 E. Breusing. Ueber das " Starkeumwandelende " Ferment im mensohlioher 
 
 Ham. Virchow's Aroh. Bd. 107, p. 186. 
 Beohterew. Nenrolog. Centrlbl. No. 20, 1885. 
 
54 
 
 LEOTUKE Y. 
 
 Gentlemen, — Our conceptions of the transmission of tlie food 
 prepared in the mouth, and the fluid taken up by it, onwards to 
 the stomach, were formerly relatively simple. By the action of 
 the proper muscles the morsel was propelled into the pharynx, 
 the entrances being closed to the nasal cavity by the palate, to the 
 air-passages by the glottis and to the anterior part of the mouth, 
 and the swallowed mass propelled downwards by the peristaltic 
 contraction of the muscles of the pharynx and oesophagus. This 
 description, which was supported by the fact that in many 
 animals, the horse for example, we can see the wave of muscular 
 contraction from the exterior of the neck, was taught by Magendie 
 and strongly held by Heuermann, the physiologist and physician 
 of the last century, and has since, with little modification, been 
 adopted by all authors. 
 
 To the labours of Kronecker, Falk, and Meltzer we owe a series 
 of new facts, which lead us to quite another conception of the act 
 of swallowing. 
 
 Partly by means of manometric estimation of the pressure in 
 the pharynx, partly by means of oesophageal tubes, which were 
 introduced different distances into the oesophagus, they succeeded 
 in analysing the different stages of the act of swallowing. With 
 this object the lower opening of the tube was provided with a 
 little inflatable india-rubber ball, and the other hand furnished 
 with a Marey's capsule. When the ball reached the desired part 
 of the oesophagus it was inflated so as to touch the walls of the 
 passage, and both by the passage of food and by the contraction 
 of the oesophageal muscles slight pressure was experienced. Any 
 active pressure on the air in the ball was conveyed through the 
 closed system to the index of the Marey's capsule, and could be 
 recorded on the rotating drum of the kymographion. 
 
 A similarly arranged ball was at the same time placed in the 
 pharynx, and its indications on the beginning of the act of swal- 
 lowing were inscribed by the index pen on the drum, so that all 
 the data for measuring the consecutive course of the movements 
 of swallowing were obtained. 
 
MECHANISM OF DEGLUTITION. 55 
 
 It was found that the swallowed matter — fluid or gruel-like — 
 in less than 0*1 second after the beginning of swallowing reached 
 the cardia, and in fact, as Kronecker believes, by the combined 
 action of the muscles of the root of the tongue, namely, the 
 mylohyoids and hypoglossi, it is squirted straight through the 
 oesophagus, so that the bolus of food, by the pressure of the 
 tongue against the hard palate, is put under high pressure as by 
 a piston. This pressure, according to Falk's measurement, in 
 the opened oesophagus amounts to about 20 cm. of water, and 
 under natural conditions must be greatly increased. It is there- 
 fore no wonder that it is possible to swallow even standing on 
 one's head. With this chief action, or rather after it, the muscles 
 of the pharynx and oesophagus come into play, and bring about 
 a wave of contraction which divides the oesophagus into three 
 sections, of which each contracts in its own sphere at about the 
 same time. In the first section, which extends downwards about 
 6 cm. from the entrance to the gullet, the wave begins 1'2 
 seconds after the commencement of swallowing, in the second (to 
 16 cm. downwards) after 3 seconds, and in the last just after 6 
 seconds. Between the contraction of the mylohyoidei and that 
 of the constrictors of the pharynx there is an interval of 0"3 
 second, and from this to the beginning of the contraction of the 
 first section of the oesophagus 1'2, less 0'3=0'9 second elapse. 
 It follows, therefore, that the pauses which occur between the 
 various phases of contraction, namely, 0'3, 0'9, 1'3, and 3'0 
 seconds, follow a definite law, and form an arithmetical series with 
 the constant factor 0'3 second. This might seem curious, if it 
 were not shown by the following circumstance to be of great 
 significance. When, for example, one, two, or more acts of 
 swallowing follow at intervals, the smaller the ascertained 
 pauses are for each section of the oesophagus, for example less 
 than 1-2 second for the first section, just so long will the con- 
 tractions of this and all lower sections be inhibited, and they 
 recur after the last act of swallowing so as to constitute with it 
 only one act. There is also a reflex (?) inhibition with each 
 excitation of the upper section afiecting all the lower ones, so that 
 the passage remains open for the bolus to pass. But it appears 
 that this only facilitates the act and is not what renders it pos- 
 sible, as it can be proved that the bolus can be forced through 
 the contracted portion of the oesophagus, and that the action of 
 
56 LECTURES ON DIGESTION. [Lect. V. 
 
 the myloliyoidei can overcome the resistance opposed to it. It is 
 an interesting fact that in hiccup a wave of contraction runs, as 
 one would not expect a priori, from ahove downwards along the 
 oesophagus. 
 
 On reaching the cardia this contraction ceases. The sphincter 
 of the mouth of the stomach rests in a state of moderate con- 
 traction, which ordinarily cuts off the stomach from the oesopha- 
 gus, but appears to yield to repeated acts of swallowing, and 
 gives admission to the cavity of the stomach. 
 
 Does the bolus of food stop, that is, does the mass propelled 
 by a single act of swallowing rest before reaching the stomach, 
 or does it go direct to the cardia, that is, as we have seen, in 
 0-1 second ? Kronecker and Meltzer are, partly from direct and 
 partly from indirect observations, in favour of the first view. 
 It is possible by auscultation to follow indirectly the passage 
 of the bolus. After the act of swallowing there occurs a peculiar 
 murmur or sound over the stomach, which was first described 
 by Natanson in 1864, but not carefully studied, and was later 
 described fully by Zenker, and finally by Meltzer, to whom at 
 least belongs the credit of having made the observation more 
 generally known. Apart from the sound produced in the 
 pharynx at the first moment of swallowing, which is trans- 
 mitted into the oesophagus, and is to be heard throughout its 
 entire course, there are two sounds separated by an interval 
 audible over the region of the cardia, and best heard at the 
 angle of the ribs. First, immediately after the beginning of 
 the act of swallowing, there is a " projection murmur," so called 
 because it has the character of a hiss, as if the fluid were projected 
 straight into the stethoscope. Some time after, in most cases 
 after 6 to 7 seconds, there occurs a second murmur, or rather a 
 complex of rapidly following sounds, which are at times gurgling 
 or clucking, at others trickling or splashing, giving the impres- 
 sion, but by no means without exception, as Meltzer thinks, of 
 air or fluid forced through a sphincter, whence it is called an 
 " expulsive murmur." It seems to me better to describe the 
 murmurs without prejudice as "first" and "second." The 
 first murmur is only seldom heard, and is, where it occurs, 
 caused by relaxation of the cardia and the direct entrance of the 
 bolus into the stomach ; the second is constant or nearly so, but 
 is exceptionally absent when the first is present. From the 
 
DEGLUTITION SOUNDS. 57 
 
 congruence in time of the latter witk the contraction of the 
 deepest section of the oesophagus, and from the rarity of the 
 former taken into connection with the circumstance that it is 
 generally alone and not followed by a second murmur, Kronecker 
 and Meltzer conclude that ordinarily the bolus stops before reach- 
 ing the stomach, and the second murmur is the resultant of its 
 entrance into the stomach, by, as above described, the contraction 
 of the last section of the oesophagus. In opposition to the view 
 of Zenker, who attributes the second murmur to air forced 
 through the cardia, Kronecker holds that the bolus throws the 
 cardia into audible vibrations, which are strengthened by the 
 resonance of the air-containing stomach. This is not possible. 
 I have observed a number of facts, which have been corroborated 
 in their most important points in a careful dissertation by 
 Dr. Dirksen, which are not in accordance with the explanation 
 given by Kronecker and Meltzer. The chief of these are the 
 occurrence of the typical second murmur without a previous 
 act of swallowing, the typical occurrence in certain persons of 
 a first and second murmur after a single act of swallowing, the 
 frequently very considerable retardation of the second sound to 
 17 and 20 seconds, and finally the artificial production of the 
 same by intra- ventricular muscular excitement by means of the 
 galvanic current! Moreover, I have convinced myself with cer- 
 tainty that in excised and suitably suspended preparations of the 
 oesophagus and stomach with artificial closure of the cardia, the 
 injection of water never causes a murmur, but the injection of air 
 is followed by an exquisite typical second sound, that is, a series 
 of bursting bubbles ; in the first case, on the contrary, one hears 
 a typical first sound, in fact, a true expulsive murmur. Finally, 
 it is possible in the living subject, by prolonged insufiiation of 
 air into the deepest section of the oesophagus, to produce a 
 distinct second sound ; on the other hand, the second sound may 
 be prevented if care is taken to swallow only fluid without air. 
 
 Finally, I have done what Kronecker and Meltzer omitted, 
 that is, I have followed the movements of the oesophageal 
 muscles with the air-ball while auscultating at the same time, 
 and I found, while confirming the careful statements of 
 Kronecker and Meltzer, that, 1. Muscular contractions occur 
 without sounds; 2. Sounds occur without contractions ; 3. Sounds 
 and contractions occur without evident swallowing movements. 
 
58 LECTURES ON DIGESTION. [Lbct. V. 
 
 and these sounds are evidently to a certain extent independent 
 of the passage of the bolus into the stomach. 
 
 Prom all this it follows that the second sound arises not from 
 the vibrations of the sphincter of the cardia and the inflowing 
 fluid, but, as Zenker formerly stated, by means of the air driven 
 in. Quincke came to quite the same results by means of 
 observations on a dog, whose stomach, however, was opened. 
 This investigator thus expresses himself: "That for the pro- 
 duction of the swallowing murmur the swallowed matter must 
 contain air." Either the swallowing murmur is the immediate 
 consequence of the contraction of the lowest section of the 
 oesophagus after the commencement of the act of swallowing,, 
 though it appears about 6 to 7 seconds later, or it comes later, 
 often without any previous act of swallowing, and is then only 
 to be explained by contraction of the oesophagus or stomach, 
 which occurs from some other stimulus than an evident act 
 of swallowing, or, at all events, without propelling any swallowed 
 material through the cardia. The circumstance depends, too, as 
 Quincke has shown, to some extent on the consistence of the 
 swallowed material, as it occurs with water more easily than 
 with thick fluids, such as gruel, and it depends for its character 
 upon the degree and nature of the fulness of the stomach. 
 
 Much more important, in my opinion, are the direct observa- 
 tions of Kronecker upon the retarded passage of swallowed 
 matter into the stomach. He was able, in a man, to palpate 
 the cardia with his finger introduced into the stomach through 
 a fistula, and to feel that nearly 6 seconds after a drink of water 
 the fluid forced open the cardia and entered the stomach. This 
 may be experimentally determined on dogs after opening the 
 stomach, as has been corroborated by Quincke. But it may be 
 objected to these observations and researches that they were made 
 under abnormal conditions, and that at any rate they are valid 
 only for that particular act of swallowing and not for ordinary 
 conditions of feeding ; otherwise there must be in every man 
 an oesophageal diverticulum, a sort of fore-stomach, such as is 
 found in some insects, for the accumulation of swallowed material 
 in front of the stomach must cause, as a necessary consequence,, 
 dilatation of the lowest section of the oesophagus. 
 
 But, gentlemen, I have taken up too much of your time with 
 this digression, as the swallowing murmurs of the stomach have 
 
THE GASTRIC GLANDS. 59 
 
 hardly yet obtained any practical significance, except that their 
 prolonged and repeatedly observed absence indicates occlusion or 
 considerable narrowing of the oesophagus. A very great number 
 of patients were examined by me last year without result as to 
 the value of the swallowing murmur in diagnosis, and Dr. Dirksen 
 came to the same result in his before-mentioned investigations. 
 At any rate the oesophagus has shown us the way to the 
 
 Stomach, 
 
 whose functions it is our next business to discuss. 
 
 Formerly we distinguished two forms of gastric glands, both 
 tube-shaped, of which one occupies the fundus, and is lined with 
 rounded nucleated cells, the so-called peptic glands (Frerichs) ; 
 the other is situated in the pyloric portion, and is lined with a 
 more cylindrical epithelium, the mucus glands. The former 
 produce the well-known gastric juice, the pepsin; the latter, 
 mucus. In addition, some observers have found acinous glands ' 
 (Bonders, Frey) . Meanwhile, this simple explanation has under- 
 gone an important extension by the simultaneous publications 
 of Rollet and Heidenhain. The structure of the gastric mucous 
 membrane, as one may easily ascertain, is the following: the 
 more or less convoluted surface of the mucous membrane turned 
 towards the stomach lumen, appears under low powers thickly 
 covered with numerous crowded pores, the openings of the deep- 
 lying gland tubules, and is invested with a tall columnar 
 epithelium, which extends into the entrances of the gland 
 tubules. In this epithelium there takes place, according to 
 Stohr, a peculiar mucous transformation of its contents, quite 
 analogous to that by which in the mucous cells of the salivary 
 glands the granular protoplasmic contents are converted into 
 hyaline mucous matter, which distends the cell and pushes the 
 remainder of the protoplasm and the previously central nucleus 
 over to the periphery. When the portion of cell membrane 
 turned towards the stomach cavity bursts, the mucus runs out, 
 and the protoplasm and nucleus take the empty cell, and form out 
 of it a new basal membrane, and the game begins anew. Here, 
 too, by the protoplasm being displaced laterally, structures or 
 appearances are prbduced similar to the " crescents " of the 
 salivary glands. In a similar fashion Toldt expresses himself, 
 though deviating a little from Heidenhain, who lays great stress 
 
60 LECTURES ON DIGESTION. [Lect. V. 
 
 on certain differences in reaction, and thinks that the cells are 
 not bounded by a membrane at their bases, but are open like 
 cornets. Moreover, the strength of this layer of epithelium, 
 that is, the limitation of it to the necks of the tubdar glands, 
 varies very much in different parts of the stomach. In the 
 pyloric region the cylindrical epithelium is equal to half the 
 depth of mucous coat, in other parts only from one-tenth to 
 one-eighth of it, so that in the region of the pylorus we find 
 in an equal superficial area fewer glands but more epithelium 
 than elsewhere. In general, several gland tubules have a common 
 excretory duct, so that according to Toldt, in a girl of ten, with 
 16,971,360 glands, there are only 2,828,560 openings; and in a 
 man of thirty, the relation is 25,179,000 to 6,790,700. Between 
 or below the epithelium lie other, apparently membraneless, 
 cellular elements, which were described by Ebstein as com- 
 pensatory cells (Brsatzzellen). Also some examples of the about 
 to be described parietal cells (Belegzelle) are here met with. 
 In these, which have, like the salivary glands, a membrana 
 propria strewn with stellate connective tissue cells, we can 
 distinguish an upper, smaller part, the gland neck, and a lower, 
 somewhat wider part, the fundus of the gland. In the neck the 
 cells are placed in a single row on the membrana propria ; in 
 the fundus they are numerous, and fill it out like stones in a 
 bag. The cells are pushed together in the middle of the tube, 
 and leave no distinct lumen to be recognised, but it is doubtless 
 present and is sometimes easily seen. If we stain alcohol- 
 preserved preparations with aniline dyes — Heidenhain employs, 
 aniline blue, Stintzing recommends recently congo-red for the 
 human mucous membrane — or with heematoxylin-chromate of 
 potash after Heidenhain- Sachs, one sees — particularly well in 
 the dog and pig, indistinctly, after one has learnt their disposition 
 in those animals, in man — in a longitudinal section of the glands 
 of the fundus, that the "neck cells" for the most part are brightly 
 stained, large, and have distinctly outlined nuclei, and in many 
 places push out the membrana propria. In the gland fundus, ' 
 on the other hand, we find smaller cells with distinctly coloured 
 nuclei and granular unstained protoplasm, which are here and 
 there replaced by a cell of the first-named sort, but which still 
 preponderate in quantity and form the principal elements. 
 Sections which have divided the gland neck vertically to the 
 
STRUCTURE OF THE GLANDS. 61 
 
 long axis of the tubule show a crown of regular, rigid, large, 
 darkly-tinged cells, whilst sections of the fundus show an 
 irregularly grouped quantity of uncoloured smaller cells, which 
 are only here and there varied by a large, coloured, roundly- 
 projecting cell placed on the membrana propria. The former 
 are visible distinctly, the latter indistinctly; the former are 
 few in number, the latter are relatively crowded and form the 
 principal elements. EoUet distinguishes them as delomorphic 
 and adelomorphic; Heidenhain, as parietal (Beleg) and central 
 (Haupt) cells. Nussbaum has seen a rare third kind of cell 
 lying between the cells in the pyloric region, in preparations 
 treated with perosmic acid. They are somewhat conical in 
 form, seated with their broad bases on the tunica propria, while 
 their small, rather clear apices extend to the lumen of the gland. 
 According to Sachs, they are to be distinguished from the 
 parietal cells by their clear staining with hsematoxylin, while 
 the latter, as above stated, become dark, almost black, yet they are 
 very much alike, and by many authors (Stohr, Dukes) are regarded 
 as identical. Between the tubules rises a sometimes greatly 
 developed support of connective tissue, interspersed with lymphoid 
 cells in the upper part, which exhibits a retiform structure in 
 brushed-out sections. With it are organic muscular fibres, 
 while the vessels of the sub-mucous trunks pass between the 
 tubuli and form a narrow capillary network around the orifices 
 of the glands. In the sub-mucous tissue impinging on the 
 fundus of the gland, I have described in man typical acinous 
 glands without any recognisable excretory duct. Ebstein has 
 undertaken a thorough investigation of the peptic and mucus 
 glands of the pyloric region with reference to the above-mentioned 
 description, and found that the pyloric glands have almost no 
 parietal cells, but an epithelium, very similar to the central 
 cells of the fundus glands, which behave themselves during 
 digestion in a manner analogous to that which we shall imme- 
 diately describe in the fundus glands. Accordingly, the stomach 
 is divided into two regions, which are already externally dis- 
 tinguished by the colour of the mucous membrane. A pale 
 pyloric portion, with few deep folds and a reddish yellow or 
 reddish grey portion at the fundus and the curvatures, which 
 exhibits an abundant irregular network of folds. Between the 
 two lies an intermediate zone, which varies in extent. 
 
62 LECTURES ON DIGESTION. [Lbct. V. 
 
 If we trace the influence which the process of digestion and 
 the function of the glands exercise on their structure, we find 
 this at its acme somewhere about the fourth hour after the 
 ingestion of food ; the tubes, as Frerichs already described, 
 being swollen out, the central cells very cloudy, swollen, and 
 {in stained preparations) coloured, the parietal cells still larger 
 and more prominent than ever. These striking changes in the 
 cells recede in the last hours of digestion, in which the distended 
 tubes shrink, but the strong colouring of the central cells remains 
 a longer time, until it gives way to the normal condition. We 
 see that, first, at the height of the digestive activity of the 
 stomach, obviously more goes into than comes out of the cells, 
 or they could not swell ; and, secondly, their contents must be 
 distinguished from those of the fasting state, or they could not 
 exercise such a much greater absorbing power on the . colouring 
 matter of the staining agent. What the nature of this change 
 may be, which in all probability represents the first stage of the 
 special secretion, our pioneer (Heidenhain) has left unsettled. 
 At a certain period of digestion, the parietal and central cells 
 must look very much alike ; and I place before you preparations 
 from the dog in full digestion, in which I can find no difference 
 between the two kinds of cells, whilst the distinctions between 
 the two kinds in the preparations from the fasting dog are very 
 noticeable. The question might well be asked, whether the central 
 and parietal cells are originally distinct cells, or only develop- 
 mental stages, if it were not, as we shall see later on, that they 
 perform quite distinct functions. Edinger had already put 
 forward a similar, but according to Heidenhain and Stohr, 
 groundless view, and Toldt holds on the basis of a careful, in 
 part embryological study of the subject, that during the entire 
 period of development the delomorphic cells originate from the 
 adelomorphio by increasing in size and successive growth of 
 the granules of the cell body which colour vividly with eosine and 
 perosmic acid. He regards the entire process as a regeneration, 
 independent of secretion, leading within greater spaces of time 
 to a gradual renewal of the cells. 
 
 The influence of the nervous system on the stomach was till 
 recently unknown, except that the innervation must run in the 
 trunks of the sympathetic and vagus. We know now very little 
 more, except that by peripheral irritation of the vagus we can 
 
INNERVATION OF THE GLANDS. 63 
 
 give rise to irregular contractions of the stomacli; the same 
 results follow reflexes from the central nervous system, in 
 particular from the medulla oblongata, whether the reflex excite- 
 ment be central or whether it be of peripheral origin, also in 
 pathological instances, in the one case of injuries and diseases 
 of the brain and spinal cord, in the other of irritation of the 
 mucous or serous membranes, the sense organs (taste, hearing), 
 dreams, &c. All more intimate knowledge of the glandular 
 innervation is wanting. The statements of CI. Bernard and 
 Prerichs, that section of the vagi is followed by interference 
 with the secreting functions, have been long ago contradicted, 
 and we stand face to face with the bare fact that mechanical 
 irritation of the gastric mucous membrane, whether by ingesta 
 or otherwise, gives rise to hypersemic reddening with copious 
 secretion ; whilst fasting stomachs, as I maintain with Hoppe- 
 Seyler, and in opposition to many recent statements (Rosin, 
 Schreiber, and others), contain no sfecretion, but only a little 
 mucus. But at any rate, there is a difference between the 
 process of secretion set up by circumscribed chemical, thermal, 
 or mechanical stimuli of the mucous membrane, and that caused 
 by ordinary ingesta or absorbable substances of another kind 
 {peptone, albumoses). The latter action is generally diffused 
 over the whole mucous membrane, while the former is limited 
 to the stimulated spot, and, moreover, may be obtained after 
 section of all the nerves leading to the stomach, and is 
 transmitted either by the nervous apparatus seated in the 
 stomach, or results from the direct stimulation of the gland 
 cells without the intervention of any nervous structures. The 
 secretion of gastric juice occurs not only reflexly through certain 
 sensory impressions, but by simple mental conceptions, and 
 such stimuli may act reflexly from the mucous membrane of 
 the mouth through the channels of the vagi and sympathetic. 
 Eichet has proved this to be true in man, in a case with complete 
 fibrous stricture of the oesophagus, where a gastric fistula had 
 been made, and in whom it was shown that when the patient 
 took into his mouth and masticated strongly-flavoured substances, 
 such as citron peel, sugar, and the like, a strong secretion of' 
 gastric juice occurred. If, moreover, the following observation 
 of Eegnard and Loye be correct, the often disputed direct 
 influence of vagus stimulation appears at any rate to be admitted. 
 
64 LECTURES ON DIGESTION. [Lect. V. 
 
 The authors in question stimulated the vagus of a decapitated 
 criminal forty-five minutes after the execution of the sentence, 
 and saw not only movements of the stomach and intestine down 
 to the transverse colon, as well as folding and wrinkling of the 
 intestinal mucous membrane, but also observed numerous drops 
 of gastric juice pouring out over the whole surface of the mucous 
 membrane of the stomach. However, it is by no means proved, 
 first, that they had to do with active gastric juice ; and, second, 
 that if it were, it was not merely a squeezing out of the 
 previously existing gland contents through the contraction of 
 the wall of the stomach, — a simple mechanical action instead 
 of a real secretion. 
 
 A contribution to the comprehension of the movements of 
 the stomach has been recently made by Goltz. If we expose 
 in a special manner the stomach and cesophagus of two vertically- 
 hanging curarised frogs, so that they can be well observed, and 
 drop a dilute watery solution of salt into both their mouths, 
 after having previously destroyed the brain and spinal cord 
 of one, the following occurs : the stomach and oesophagus of 
 the normal frog are widely distended, full of fluid, quite 
 motionless, only traversed by a to-and-fro peristaltic wave, and 
 look like a blown-up pig's bladder. The oesophagus and stomach 
 of the frog deprived of its brain are empty, and beaded in many 
 places by sharp muscular contractions, which run peristaltically 
 from above downwards. The same occurs when the vagi are 
 cut, whilst electrical stimulation of these nerves only causes 
 slight contraction. This experiment, which may be extended 
 by exciting reflex movements, is easily performed, and, as you 
 see, is of striking signiflcance. In fact, one can conceive no 
 gireater contrast than the stomachs of the two animals, especially 
 as it increases with time; for the parts concerned in the frog 
 deprived of its brain dry in the air quicker than the other. 
 Goltz concludes from this that an independently acting system 
 of ganglion cells (analogous to the plexus myentericus) is present 
 in the stomach, the irritation of which gives rise to local con- 
 tractions and peristaltic movements, but which is in connection 
 through the vagi with the medulla oblongata, which exercises 
 
 a controlling efiect on the functions of these ganglia; an 
 
 explanation which is quite familiar to us from the reflex con- 
 trolling centres for the extremities in the spinal cord. If by 
 
MOTOR INNERVATION. 66 
 
 destruction of the medulla or section of the vagi the controlling 
 influence is wanting, a very strong action of the centres in the 
 stomach follows stimuli which not only escape the observer, but 
 are without effect on the normal stomach, just as we observe an 
 increased reflex excitability in certain diseases of the spinal 
 cord — for example, sclerosis, hemorrhage, &c. The theory 
 unites proved and unproved views; moreover, the experiment 
 succeeds invariably and without difliculty. But the ganglionic 
 plexus postulated by Goltz, though not, proved by him, is present 
 according to Openchowski, who has recently communicated the 
 results of a remarkable series of experiments, extending over 
 years, on the innervation of the stomach. This investigator 
 succeeded in proving the existence of separate complexes of 
 ganglionic cells in the cardia and pylorus, near the structures 
 which are admitted to be extensions of the mesenteric and 
 Auerbach's plexuses. By means of a special method of regis- 
 tration, described on p. 54, and methodical stimulation of 
 special nerves and definite parts of the brain and spinal cord 
 respectively, after section or amputation of particular portions 
 of the central nervous system, this author came to the following 
 conclusions respecting the nervous arrangements which control or 
 regulate the movement of the stomach in its widest meaning. 
 
 Opening and closure of the cardia and pylorus, as well as the 
 movements of the intermediate portion of the stomach, are 
 worked automatically by the above-described complex of gang- 
 lionic cells. But the stomach is also in relation with certain 
 centres in the brain and spinal cord through the medium of 
 the vagus, the sympathetic, and the splanchnics. 
 
 A centre for the contraction of the cardia is situated in the 
 region of the posterior pair of the corpora quadrigemina, and 
 is in connection with the stomach chiefly through the vagi, in 
 a less degree through the spinal nerves, which are derived from 
 the dorsal cord, and take their further course through the vagi. 
 Another centre for the opening of the cardia lies in the cerebral 
 ganglia, where the caudate and lenticular nuclei join near the 
 anterior commissure, and is also connected with the stomach 
 through the vagus (nervus dilatator cardias). Independent 
 centres for the dilatation of the cardia seem also to be found in the 
 upper spinal cord, and leave it down to the fifth dorsal vertebra 
 through the boundary zone. In the above-named situations, 
 
 5 
 
,66 LECTURES ON DIGESTION. [Lbct. V. 
 
 however, there are at the same time centres for the movements 
 of the stomach and of the pylorus ; contractions of the stomach 
 wall are produced from the corpora quadrigemina, and controlling 
 centres for the same are situated in the upper portion of the spinal 
 cord, whose course lies through the sympathetic and splanchnics. 
 For the pylorus there is a controlling centre in the corpora 
 quadrigemina, while in the olivary body there is another for 
 opening it. There is an express antagonism between the inner- 
 vation of the cardia and the pylorus, as shown by the fact that 
 stimulation of the nervus dilatator cardiae makes it act as a closer 
 of the pylorus, and the same may be observed in the higher 
 centres in the cerebral ganglia, and also in the cortical centres 
 found by Openchowski in the crucial sulcus. 
 
 We have, therefore, to do with a very complicated mechanism 
 of innervation in the stomach, if these data are confirmed, and 
 the careful and- extensive series of researches of Openchowski 
 afford a guarantee of their truth. The contemporaneous opening 
 and shutting-of the cardia and pylorus are of great interest. It 
 is a purposeful mutually useful arrangement, similar to that 
 which we shall see later on exists in the innervation of the 
 intestine and also in other places, as, for example, in the self- 
 regulation of the lungs. 
 
 Moreover, the experiments accord, so far as concerns the 
 automatic action of the nerve centres in the stomach, with 
 already known facts. Oser saw in stimulation of the vagus 
 contraction of the pylorus, and spontaneous (i.e., regulated by 
 the local ganglia) movements of the pylorus were controlled by 
 stimulation of the splanchnics in the abdominal cavity. 
 
 When Hofmeister and Schutz observed the recently excised 
 stomachs of dogs in warm chambers at the temperature of the 
 body, they saw quite typical movements within the first sixty 
 to ninety minutes, the stimulus for which must have beeli 
 existent in the stomach itself. Certainly it is not yet decided 
 by these experiments whether these were physiological move- 
 ments of the surviving organ, or whether we have to do with 
 an abnormal stimulus due to the anaemia, a point which the 
 investigators quite overlooked ; but the course of the movements 
 appears to have been so typical, that their legitimate character 
 seemed to them undeniable. According to their account, they 
 occurred at first in progressive, gradually increasing waves of 
 
STOMACH PERISTALSIS. 67 
 
 contraction from the cardia to witHn 2 cm. above the pylorus, 
 in which the muscular waU of the great curvature specially took 
 part. In the place named these contractions came to a stop, 
 and for a short time remained quiet, while at the same time the 
 contraction of the pyloric portion of the stomach began. At a 
 certain moment the orgati assumed an hour-glass shape, with 
 a larger cardiac swelling and a smaller pyloric swelling. When 
 the pr^central contraction relaxed, the contraction of the longi- 
 tudinal and circular fibres of the pyloric portion reached its 
 highest point, contemporaneously without peristalsis, and the 
 entire movement ended with a concluding contraction of the 
 pylorus. In this fashion the contents of the stomach are at a 
 certain time divided into two parts, of which the larger consists, 
 as these investigators consider probable, of the bigger and harder 
 masses, the smaller of the fluid, or at least of reduced material 
 ready for transmission into the intestine. The stomach is one ana- 
 tomically, but there is no uniformity in its function, as the fundus 
 performs the function of chemical digestion, while the pyloric 
 portion regulates the passage of the chemically-changed contents 
 into the intestine, and possesses a power of selecting the mate- 
 rial which is ready for transfer. Gentlemen, I cannot accept 
 this view. The plain fact that the pyloric portion secretes a 
 strongly digesting fluid containing pepsin and hydrochloric acid, 
 proves it to be an important part for the peptonising function 
 of the stomach. 
 
 Not in harmony with the above-described movements in the 
 surviving organ are the observations of Eossbach on the living 
 stomach. According to these, the fundus remains without any 
 movement. The contractions begin always at the same place, 
 in the centre of the stomach, run continuously to the pylorus, 
 and remind us only of the descriptions of Hofmeister and 
 Schutz, in so far as the strongest constriction takes place in the 
 region of the antrum pyloricum Willisii. 
 
 Openchowski's observations are in harmony with these. In 
 direct opposition to the results of Goltz's experiments is the 
 observation of Eossbach, who found the stomach contracted 
 after section of the spinal cord at the level of the second 
 cervical vertebra or section of the vagi, whereas by analogy 
 with Goltz's experiments it should be dilated. There is a 
 further ground for the belief that in these and Hofmeister's 
 
68 
 
 LECTURES ON DIGESTION. 
 
 [Lect. V. 
 
 experiments we have to do with phenomena of irritation from 
 ansemia. According to their view, the pylorus during the whole 
 of digestion must remain shut, and open itself actively at the 
 conclusion so as to allow the stomach contents to escape. I 
 will not dispute the latter relation in dogs ; for men, however, 
 it is not valid. The results obtained by Dr. Boas and myself 
 in observations made by removal of the stomach contents with 
 the tube in all stages of digestion, show that chyme passes 
 into the intestine, not suddenly but gradually, and this passage 
 stands in relation to the amount of hydrochloric acid in the 
 chyme, as was proved also by Pfungen in a gastrotomised lad, 
 in whom acids exerted a controlling influence and alkalies a 
 relaxing influence on the pylorus. 
 
 But we shall speak of the course of the movements in the 
 stomach and its motor functions, when we come to treat of the 
 passage of the chyme into the intestine (v. Lecture VIII.). The 
 other nervous relations of the stomach in connection with its 
 sensibility, and the rightly or wrongly localised general 
 sensations, such as hunger, satiety, &c., and our knowledge 
 of the process of vomiting, will be found described in the 
 second part of this volume, and may be here passed over. 
 
 Pure, unmixed gastric juice was first known when Bidder and 
 Sshmidt produced gastric fistulas in animals, and at the same 
 time tied all the ducts of the salivary glands to prevent swallow- 
 iag saliva. Such gastric juice has the following composition : — 
 
 Gastric juice of Dog free from saliva. 
 Mean of 10 analyses. 
 
 Gastric juice of 
 
 Man containing 
 
 salira. 
 
 Blood serum of 
 Man. 
 
 Water 
 Solids 
 
 973-06 
 26-94 
 
 Containing : 
 
 Peptone and pepsin 17-19 
 
 Free hydrochloric acid 8-05 
 
 Alkaline chlorides 4*26 
 
 Ammonium chloride 0-47 
 
 Containing chlorine ... 6-06 
 
 Phosphates 
 
 Lime 1-73 
 
 Magnesia 0-23 
 
 Iron. 0-08 
 
 994-6 
 5-4 
 
 903-0 
 97-1 
 
 .3-02 
 .0-22 
 .2-0 
 
 Organ, mat. 88-5 
 Inorganic 8-6 
 7-2 
 
 .0-15 
 
 3-6 
 
 0-5 
 
THE GASTRIC JUICE. 69 
 
 Here you have an analysis of human gastric juice as obtained 
 from a gastric fistula, and the comparison with an analysis made 
 by Lehmann of human serum. The large proportion of chlorine 
 in the gastric juice as compared with blood serum will strike 
 you, whilst, conversely, although it is certainly not distinctly 
 brought out by the analysis, there is about one-half less alkali 
 in the gastric juice than in blood. That the human gastric juice 
 in the above table contains about ten times less hydrochloric 
 acid than that of the dog need not astonish you. The first is 
 abundantly mixed with water or saliva, but pure human gastric 
 juice, freed as far as possible from saliva, contains less hydro- 
 chloric acid than that of the dog, and varies, according to the 
 analyses of Szabo and Boas and myself, between two and three 
 parts per mille. 
 
 The reaction of the gastric juice is always very acid. The 
 mucous membrane of a recently killed animal possesses an acid 
 reaction wherever it comes in contact with the gastric juice. 
 There is little interest in following historically the discussion 
 of the question as to which acids give rise to this reaction. 
 Bidder and Schmidt have proved by an unimpeachable method 
 that it is free hydrochloric acid. They estimated the entire 
 chlorine and the entire bases, reckoning these all as chlorides, 
 in a measured quantity of gastric juice, and found more chlorine 
 than would be necessary to convert the bases into chlorides. 
 This overplus of chlorine can exist only as hydrochloric acid, 
 free or in an organic combination. But the excess of chlorine 
 corresponds to the equivalent of an alkali (barium), which must 
 be added to the same quantity of gastric juice as was used in 
 the experiment up to neutralisation; so it follows that, first, 
 free hydrochloric acid is present; and, second, other acids, if 
 there be any, are present in only very slight traces. This 
 investigation has finally decided the dispute concerning the 
 nature of the gastric acid, which had attained such dimensions 
 that no fewer than twelve authors have pleaded for lactic acid, 
 fourteen for hydrochloric acid, and two for phosphoric acid, 
 finally agreeing with Prout, who as early as 1824 proved the 
 existence of hydrochloric acid in the gastric juice. Tn such 
 investigations it is necessary to draw a strong distinction 
 between the pure secretion of the gastric mucous membrane 
 and the stomach contents after the introduction of food, which 
 
70 LECTURES ON DIGESTION. [Lect. V. 
 
 are a mixture of gastric juice, and according to the nature of 
 the aliment, of very varying matter, salts, &c. 
 
 Moreover, there is also present, as already other authors 
 (Lehmann, Frerichs, and others) had suggested, and Dr. Boas 
 and I have proved, an organic acid, lactic acid, in fresh not 
 pathological stomach contents, yet it is not a product of 
 glandular secretion, but is a consequence of the normal fer- 
 mentation of carbo-hydrates in the stomach, or is brought into the 
 stomach ready made in certain food and only increased there. 
 We find, indeed, in extracts of the gastric mucous membrane 
 slight traces of lactid acid, but these are imbibed from the 
 stomach contents, and are not produced in the membrane, which 
 is shown by the fact that parts destitute of glands, situated 
 at the cardia, also give an acid reaction, and contain traces 
 of lactic acid. We (Ewald and Boas) have shown that at the 
 commencement of the digestion of a meal of bread, or meat with 
 bread or potatoes, by a healthy man lactic acid, or, according 
 to the accidents of fermentation, sarcolactic acid, is always 
 present. It may be demonstrated with certainty during the 
 first ten to thirty minutes after the ingestion of a meal, and 
 then disappears so soon as the quantity of free hydrochloric 
 acid becomes noticeable, till only traces are left. As a rule, 
 there is an intermediate stage between those in which only 
 lactic acid or only hydrochloric acid is present, in which both 
 may be met with. In fasting, unstimulated stomachs there is 
 neither lactic acid nor hydrochloric acid, but after a meal not , 
 containing any lactic acid-producing matter, such as pure egg 
 albumen, the stomach contents can be shown for any length of 
 time to contain only free hydrochloric acid, and this is the case 
 almost immediately, or from seven to ten minutes after eating. 
 It appears to begin at the moment of the introduction of food 
 into the stomach, but is taken up so long, and is, therefore, not 
 present in a free state, as it on the one hand meets with 
 albuminous bodies, which imbibe it and form with it close 
 combinations, and on the other there are salts or bases whose 
 affinities must be satisfied. So long, therefore, as there is room 
 for all kinds of fermentative processes, it is not possible to 
 fix the time at ivhich jree hyd/rochloric acid is present in the 
 stomach, and all estimates, of which a number exist in literature, 
 are valid only for the kind of meal used in the case in question. 
 
THE GASTRIC ACIDS. 71 
 
 There is, However, as we (Ewald and Boas) Have stated in our 
 work published in 1885, a cm-tain antagonism hetween hycl/ro- 
 chloric acid and lactic acid, so that in proportion as the former 
 increases in amount and is found free in the stomach, the 
 formation of the latter is arrested, and that by the absorption 
 and transference of the stomach contents into the intestine 
 it gradually disappears. This view is indeed disputed by 
 Rosenheim, who thinks " there can be no question of such an 
 antagonism," but it has been confirmed by E. Cohn in a series 
 of experiments performed under the direction of Hoppe-Seyler. 
 According to these, acetic acid fermentation is inhibited by 
 traces of free hydrochloric acid, 0"05 parts per mille. Lactic 
 acid fermentation, indeed, requires more to prevent it, namely, 
 0'7 per mille, but this figure is a good deal below that of the 
 normal gastric juice, which contains 2 to 3 per mille. It is 
 understood that we are speaking of free acid, or the combination 
 of chlorine, pepsin, and hydrogen, for the inhibition does not 
 take place so long as albumen, or bases or salts are present 
 in the stomach and combine with the acid secreted. But it 
 cannot be sufficiently emphasised that in the discussion of the 
 above questions and cognate subjects in the range of pathology, 
 we must distinguish between the hydrochloric acid actually 
 secreted and that demonstrable as free acid in the stomach 
 after the introduction of food. From not considering this 
 circumstance, a number of contradictory statements exist, and 
 to this may be traced the controversy between Eosenheim and 
 Ewald and Boas (v. Oentrlbl. f d. med. Wissensch., 1889, p. 242, 
 et seq.). Our statements, which were contested by Eosen- 
 heim, but, let it be said at once, were confirmed by numerous 
 authors, referred to the demonstration of free hydrochloric acid 
 in the stomach and the actual time of its appearance after a 
 fixed meal, whilst Rosenheim referred to the presence of the 
 actually secreted hydrochloric acid which in certain early stages 
 of digestion is combined with the albuminates, salts, and bases 
 of the ingesta. It is plain to any moderately educated chemist, 
 though, as we have observed, it was for long overlooked, that 
 free acids can only exist in a complex fluid when all its basic 
 components are satisfied. 
 
 Moreover, when we consider the methods of demonstrating acids 
 in the stomach contents, we must distinguish between testing 
 
72 LECTURES ON DIGESTION. [Lect. V. 
 
 for free acids and testing for acids actually secreted or formed 
 by fermentation. 
 
 For tlie practitioner, it is of the first importance to discover 
 free acid in the stomach contents and to determine its nature. 
 As I shall discuss this subject in the second part of this book, 
 I need say here only briefly that the best reagent for free 
 hydrochloric acid is that recommended by Giinzburg, composed 
 of phloroglucine 2 grms., vanilline 1 grm., and absolute alcohol 
 30 grms. The reaction is that a splinter dipped in the solution 
 becomes deep red when touched with hydrochloric acid, due, 
 according to Singer, to the presence of vanilline. Fluids which 
 contain one-twentieth part per thousand of free hydrochloric 
 acid, give with this reagent, if previously warmed, crimson 
 streaks varying in intensity with the amount of free acid present. 
 If we have to do with a solution of unlinown strength, it is 
 possible to make an approximate estimation by repeated dilutions 
 until the reaction scarcely appears. 
 
 The precautions necessary to take with this reaction, and the 
 other tests for free acids or acid salts, as well as the estimation 
 of the acidity of the stomach contents, will be found in the 
 second part of this work. In the stomach, however, hydro- 
 chloric acid can exist not only in a free state, but also combined 
 with bases and bodies comporting themselves as bases (albu- 
 minous bodies and their derivatives), but these give a negative 
 result to the reaction for free acids. Would we know, more- 
 over, whether the acid is actually secreted, we must employ a 
 procedure by which the acid, or rather the essential part of it, 
 the chlorine, is driven out of combination and estimated as such. 
 Of all the methods hitherto proposed, that of Sjoqvist is the 
 best. It consists in neutralising a definite quantity (10 cc.) 
 of filtered stomach contents with barium carbonate and then 
 reducing it to ash. By this means all the organic compounds 
 of hydrochloric acid are converted into barium chloride, and 
 this may be estimated by means of a solution of bichromate 
 of potash. We have often employed this method, and have 
 proved its utility and accuracy, provided that the greatest 
 care is taken to avoid all chlorine-containing reagents, filter 
 papers, &c. 
 
 For lactic acid we possess a very good and certain test, 
 provided we avoid fallacies from impure reagents, in a weak 
 
TESTS FOR STOMACH ACIDS. 73 
 
 solution of ferric chloride or a mixture of a few drops of 
 carbolic acid and ferric chloride diluted with water to the 
 colour of amethyst blue. The amethyst blue or quite pale 
 yellow colour turns in the presence of very minute traces of 
 lactic acid (less than half per mille) to a bright canary yellow. 
 It can be used directly to the filtered stomach contents, as it 
 is not affected by the presence of peptone or of salts ; but if 
 there is any reason to doubt its accuracy, or should the colour 
 not be a beautiful yellow (and this only is characteristic), a 
 small quantity of the stomach contents should be shaken with 
 ether, the ether evaporated, the residue taken up with a little 
 water, and the reaction repeated with this, the result then being 
 absolutely certain. 
 
 The ferric-chloride carbolic solution serves also, as may be in- 
 terpolated here, for the recognition of the fatty acids occasionally 
 present, especially butyric acid, which gives the amethyst blue 
 solution a smoky yellow colour. If we perform the somewhat 
 troublesome extraction with ether, the result of the reaction 
 is confirmed by finding fat drops in the ethereal residue when 
 taken up with water, for there is always fat in the stomach 
 contents when fatty acids are present, and this is dissolved 
 by ether. 
 
 With the aid of these reactions we can recognise the nature 
 of the acids in the stomach contents within certain^limits. 
 
 The procedure of Richet-Berthelot, formerly described and 
 confirmed by me, for estimating the so-called co-efficient of 
 partage, depends upon the different but constant capacity of 
 ether to take up mineral and organic acids. 
 
 If an acid fluid is shaken with ether, the latter assumes a 
 different, but for each acid a constant degree of acidity, which 
 is easily estimated ; it is possible to estimate such acid present 
 in a mixture of unknown organic and inorganic acids by 
 successive shakings. This method is practicable for simple 
 pure chemical mixtures of acids, but it is not only very trouble- 
 some, but it is not possible to employ it, as I have shown, in the 
 conditions of the gastric juice. It has led Eichet to the false 
 conclusion that the hydrochloric acid is secreted in combination 
 with leucin. Apart from the fact that I have directly proved 
 that leucin (and tyrosin) are not present in the secreted gastric 
 juice or in the mucous membrane of a fasting animal, the 
 
74 LECTURES ON DIGESTION. [Lbct. V. 
 
 metkod of successive agitations with ether cannot be employed, 
 and is not practicable in a mixture of organic bodies — acids 
 and bases — alone, or in combination with inorganic acids, as 
 is always the case with the gastric juice. 
 
 Leucin and tyrosin are present, as was shown by Kiihne and 
 Uffelmann, long before Richet or even myself, in the gastric 
 contents and stomach mucus of a digesting animal, but they 
 are to be regarded as the products of decomposition of the 
 ingesta and not as the products of glandular secretion. 
 
 The proportion of hydrochloric acid in pure human gastric 
 juice, in accordance with statements already made for the dog, is 
 given by Szabo as three per mille, whilst Richet found 1'3 — 1-7 
 as the mean of seventy observations. His investigations were 
 made upon a gastrotomised patient with an impermeable stricture 
 of the oesophagus. 
 
 Now-a-days we do not find it necessary, like Gosse, who swal- 
 lowed air in order to vomit his stomach contents, to give emetics 
 in order to obtain the stomach contents at any time. Since we 
 have taken to use the soft india-rubber tube instead of the old 
 stiff pipe, the introduction of the " stomach-tube " has become 
 greatly facilitated. 
 
 It is not difficult to obtain so-called undiluted gastric contents, 
 that is, chyme formed after a given meal, without the use of a 
 stomach pump or siphon. It is only necessary to introduce the 
 tube and press on the abdomen to obtain gastric juice relatively 
 little diluted. 
 
 The numerous observations I have made on people two hours 
 after swallowing some green tea (without milk or sugar) and dry 
 white bread, have shown that the proportion of hydrochloric acid 
 lies between 1'5 and 2 per mille, and consequently for pure 
 gastric juice must be somewhat higher. 
 
 That the hydrochloric acid is formed from the chlorides of the 
 blood is a priori to be concluded, and has been experimentally 
 proved by the investigations of Voit, and especially through the 
 careful series of experiments of Cahn, which showed that the 
 hydrochloric acid disappeared when chlorides were excluded from 
 the food. 
 
 The hydrochloric acid is formed by the splitting up of the 
 various chlorine compounds, especially chloride of sodium, the 
 alkali remaining in the blood . 
 
SOURCE OF HYDROCHLORIC ACID. 75 
 
 During digestion, that is, when hydrochloric acid is secreted 
 in the stomach, the blood becomes richer in alkalies than it is 
 during the repose of the stomach glands, and at the same time 
 the urine secreted is richer in alkalies, less acid, and even some- 
 times distinctly alkaline. Bence Jones actually made these 
 observations, and taught this quite correctly in the beginning 
 of this century (1819). By other investigators, Quincke, Maly, 
 Gorges, Hiibner, and Sticker, they have been confirmed and 
 extended, so as to embrace pathological conditions. It is 
 obvious that the relations between the ingestion of food and the 
 urine must fail when the diseased stomach secretes no hydrochlo- 
 ric acid, and it may be stated that the deficiency of acid in 
 the urine gives some idea of the amount of hydrochloric acid 
 secreted — of course only provided that the increased alkalinity 
 of the urine is not due to the absorption of alkaline food, as is 
 suggested by Roberts. 
 
 But if the latter were the case, the deficient acidity of the 
 urine would not fail to appear, in spite of deficient production of 
 hydrochloric acid in the stomach, in cases of cancer or atrophy 
 of the stomach, or in severe gastric catarrh, so long only as the 
 absorbing power of the mucous membrane was preserved, and on 
 the other hand it could not occur if the secretion of hydrochloric 
 acid was excited by ingesta very poor in alkali. 
 
 Finally, the ordinary diminution of acidity must take place 
 if absorption is delayed, but the formation of hydrochloric acid 
 not interfered with. The experiments which Hiibner and Sticker 
 have made under the above-named conditions support the theory 
 of Jones and the law formulated by Quincke, that diminution of 
 the acidity or alkalinity of the urine may be effected in two ways : 
 first, by the taking up of large quantities of alkali in the blood 
 (alkalies combined with carbonic acid or vegetable acids, absorp- 
 tion of alkaline exudations) ; and second, by loss of acid to 
 the organism, by vomiting the acid contents of the stomach, or 
 by the combination of the bases to' form insoluble salts. The 
 latter was pointed out by Maly, who administered calcium or 
 magnesium carbonate to dogs, in which he had excited a strong 
 flow of gastric juice, and found that after fifteen to twenty 
 minutes their previously acid urine became alkaline. The excre- 
 tion of hydrochloric acid causes a physiological want of acid 
 in the organism resembling the want of alkali which results from 
 
76 LECTURES ON DIGESTION. [Lbct. V. 
 
 the secretion of the alkaline pancreatic juice. At this time, how- 
 ever, the urine must undergo a change, as Quincke declared, in 
 the direction of increase of acidity. Both processes balance 
 each other, and to some extent occur side by side, and control 
 each other to a certain degree. This accounts for the variations 
 in the acidity of the urine in the course of twenty-four hours, 
 which, however, do not always strictly conform to these con- 
 ditions. The hydrochloric acid secreted during digestion is 
 absorbed in the form of chlorides or loose combinations with 
 peptone, and compounds of chlorine from the food are taken up, 
 so that we find (Sticker) the excretion of chlorides in the urine 
 increased after the principal meal, but also at times reduced by 
 the action of salts, such as calcium carbonate, which form 
 little soluble chlorides, hindering the absorption of hydrochloric 
 acid. 
 
 There still arises the interesting and hitherto puzzling question, 
 what are the causes that bring about the secretion of acid, and, 
 moreover, of a mineral acid gastric juice from the alkaline 
 blood ? A brilliant experiment of Maly's has thrown an un- 
 expected light upon this. There are fluids of alkaline reaction 
 containing an acid and an alkaline salt which are mutually in- 
 active, but still give an alkaline reaction, because the acid 
 reaction is to a certain extent eclipsed : for instance, a solution 
 of neutral phosphate of soda (Naj H PO4) and acid phosphate 
 of soda (Na Hj PO4) is alkaline. Such a solution placed in a 
 dialyser after a short time gives up its acid salt to the sur- 
 rounding distilled water, and one has in the dialyser an alkaline 
 fluid outside an acid fluid. Maly proved that in blood, in 
 spite of its alkaline reaction, acid phosphate of soda as well as 
 free hippuric and uric acids are present. These acids and acid 
 compounds have a greater diffusive power than the neutral salts. 
 Hence the excretion of acid urine from the renal parenchyma 
 is analogous to the action of a dialyser. Further, if we mix 
 together neutral phosphate of soda with calcium chloride (Ca 
 OI2), we get calcium triphosphate, sodium chloride and free 
 hydrochloric acid, as in the following equation : — 
 
 2 Na, HPO4+3 Ca Cl2=Ca3 PO4+4 Na Cl+2 HCI. 
 
 According to the harmonising statements of Pribram and 
 (lerlach, lime (Ca 0) is present in the blood, and therefore allows 
 
SECRETION OF HYDKOCHLORIC ACID. 77 
 
 an opportunity for the formation of free hydrochloric acid. 
 Hydrochloric acid possesses a high diifusive power — it passes 
 thirty-four times (Graham) as quickly through the dialyser as 
 common salt; and this explains how, once formed as above in the 
 blood, it may pass into the gastric juice in such large quantities 
 as in fact we find it to do. The facts that we secrete acid urine 
 and acid gastric juice are meanwhile divested of their strange 
 characters by the aid of this simple process of diffusion ; but the 
 question why phosphatic salts are only diffused in the kidney, 
 and hydrochloric acid in the stomach, and that indeed only peri- 
 odically, must be left for the future to answer, as the hypothesis 
 of Maly in support of his theory, that the peptic glands and also 
 the kidneys and sweat glands constitute diffusion bodies, is still 
 only a description of existing relations unsupported by any facts. 
 These ideas have been also expressed by Heidenhain, but he 
 has not named perhaps the most important difficulty, that of 
 physically explaining the periodical secretion of hydrochloric 
 acid, although in all other glands which secrete periodically, 
 that is, through a special nerve stimulus, a specific secretion, 
 we conclude that this is formed by the specific activity of the 
 secreting cells, whilst the common source, the constituents of 
 the blood serum, exhibit a very changing composition. Heiden- 
 hain asserts, on the faith of a discovery of Griitzner, according to 
 which the amount of chlorides in the gastric mucous membrane 
 is proportional to the amount of peptone, that the hydrochloric 
 acid is separated from the chloride of sodium in the glands, by 
 the aid of organic acids and even of lactic acid. Landwehr 
 says the same, and derives the necessary lactic acid from a 
 ferment formed in the stomach mucus. But this hypothesis 
 fails in the chief point, that is, the necessary lactic acid, as 
 Leube and Boas and I have shown that on feeding with pure 
 albumen there is a strong hydrochloric acid reaction in the 
 stomach, but not a trace of lactic acid is to be found. Ellen- 
 berger and Hofmeister, too, have directly shown that in the 
 stomach of the horse, which is specially suitable for such experi- 
 ments, hydrochloric acid is only found in a limited part of the 
 stomach, in the fundus portion, where parietal cells are present, 
 while lactic acid and chlorides may be found everywhere. 
 
78 LECTURES ON DIGESTION. [Lect. V. 
 
 A. Eoliet. Ueber die blinddarmformigen Driisen dea Magens. Ctrlblt. f. d. 
 
 med. WissensoMt. 1870, p. 325. 
 Eoliet. Bemerkungen zur Kenntnisa der Labdriisen und der Magensobleimliaut. 
 
 Unters. aus d. Inat. f. Physiolog. u. Histolog. in Graz. ii. p. 143. 
 Heidenhain. Untersuebimgen uber den Ban der Labdruaen. M. Schultze's 
 
 AtoMt. i. microscop. Anatomie, Bd. vi. 1870, p. 368. 
 "W. Ebatein. Beitrage zur Lehre Tom Ban nnd den physiolog. Funotionen der 
 
 aogenannt. MagenscUeimdrilsen. Ibid. Bd. vi. 1870, p. 515. 
 Goltz. Studien liber die Bewegung Ton Speiaerohre und Magen. d. FrSsehe. 
 
 Pflnger's Arehiv. Bd. vi. p. 588. 
 TJffelmann. Beobaohtungen und TJntersuohungen an einem gastrotomirten 
 
 fiebernden Knaben. Deutaoh. Arohiv. f. klin. Medioin. Bd. xx. p. 538. 
 Kiihne. Weitere Mittheilungen liber die Verdaunngsenzyme und die Verdannng 
 
 der Albumine. Verhandlg. des Naturhist. med. Vereins zu Heidelberg. Bd. i. 
 
 4Hft. 
 Eiohet. Du sue gastrique ohez rhomme et les animaux. Paris, 1878. (Con- 
 taining alao a detailed historical review of the discuasion on the nature of the 
 
 gastric juice.) 
 Berthelot. Annales de Chimie et de Physique. 4 a^r. t. xxvi. p. 396, 1872. 
 Szabo. Beitrilge zur Kenntniss der freien Siiuren des menschl. Magensaftes. 
 
 Ztschrft. f. physiolog. Chemie, i. p. 140. 
 Maly. Untersuchung liber die Mittel zur Saurebildung imOrganismus. Ztschrift. 
 
 f. physiolog. Chemie, i. p. 174. 
 Pribram. Eine nene Methode zur Bestimmung des Kalkes und der Phosphorsaure 
 
 im Blutserum. Arbeiten d. physiolog. Anatalt zn Leipzig, 1871, p. 63. 
 Gerlaoh. Ueber die Beatimmung der Minerale des Blutserums dnroh directe 
 
 Fallung. Arbeiten aus der physiolog. Anstalt zu Leipzig, 1872, p. 99. 
 
 Meltzer. Schluckgeriiuache im Scrobicnlus cordis u. ihre physiol. Bedeutung. 
 Centralbl., 1883, No. 1. 
 
 Kronecker. Die Schlnckbewegung. Vortrag, gehalten in der Gesellaohaft fiir 
 
 Heilknnde zu Berlin, 1884. See also H. Kronecker and S. Meltzer, Der Schluok- 
 
 meohaniamua, seine Erregnng und seine Hemmnng. Du Bois' Arohiv., 1883, 
 
 Suppl. p. 337. 
 Falk. Ueber den Mechanismus der Schlnckbewegung. Du Bois' Arehiv., 1880, 
 
 p. 296. 
 Zenker. Ueber die Sehlinggeriiusohe. Berl. klin. Wochenachr. 1884, No. 3, 
 
 p. 83. 
 Dirksen. Beitrag zur Lehre von den Schluckgerausohen. Inaug. Dissert. 
 
 Berlin, 1885. 
 C. A. Ewald. Ueber das Schluckgerausch. Berl. klin. Woohensohr. 1883, 
 
 No. 52, and 1884, No. 3. 
 
 Toldt. Die Eutwiokelung und Ausbilding der Drliaen dea Magena. Wiener 
 Sitzungsber., 1880. 
 
 Ph. Stahr. Ueber das Epithel des menschlichen Magens. Terhandl. der physik. 
 ' med. Geaellsch. zu Wiirzburg. xv. Bd. 1881, p. 101. 
 
 Ph. StShr. Ueber SohleimdrUsen. Ibid. 1884. Lehrbnch der Histologic, 1889. 
 
 Ph. Stahr. Zur Kenntniss des feineren Banes des menschlichen Magenschlaucha. 
 
 M. Schultze's Arehiv. Bd. 20, p. 221. 
 A. Sachs. Zur Kenntniss der Magendriisen bei krankhaften Zustanden. Inaug. 
 
 Dissert. Breslau, 1886, and Arch. f. exper. Path. Bd. xxiv. 
 
BIBLIOGKAPHT. 79 
 
 Hofmeiater and SohUtz. Automatiaohe Magenbewegnngen. Aroh. f. Exp. 
 
 Path. XX. Separatabr. 
 Bossbacli. Ueber die Bewegnngen des Magens. Verhandl. dea Congr. f . inn. 
 
 Med. 1885, p. 212. 
 Ewald and Boas. Znr Physiologie und Patbologie der Verdauung. Virchow's 
 
 Arch. Bd. 101, p. 325. 
 Quincke. Correspondenzbl. f. Schweizer Aerzte. 1874, No. 1. 
 Maly. Chemie der Terdauungssafte. Hermann's Handb. Bd. v. 2, p. 69. 
 A. Cahn. Die Magenverdauung im Chlorhtmger. Zeitschr. f. physiol. Chemie. 
 
 Bd. i. p. 522, 1886. 
 Gorges. Ueber die unter physiologischen Bedingungen auftretende Alkalascenz 
 
 dea Hams. Aroh. f. Exper. Path. Bd. xi. p. 156. 
 Sticker and HUbner. Wechselbeziehungen zwischen Secreteii nrid Excreten dea 
 
 Organismns. Zeitschr. f. klin. Med. Bd. xii. p. 114. 
 Sticker. Ueber den Einfiusa der Magenssaftabsonderung auf den Chlorgehalt 
 
 dea Harns. Berl. klin. Woohenschr. 1887, No. 41. 
 Heidenhain. Physiologie der AbsonderungsTOrgclnge, &o. Hermann's Handb. 
 
 Bd. V. p. 151. 
 Griltzner. Neue Untersuchungen Uber die Bildung und Anssohiedung des 
 
 Pepsins. Breslan, 1875. 
 J. SjOqTist. Eine neue Methode, freie Salzsaure im Mageninhalte qnantitativ 
 
 zn bestimmen. Zeitschr. f . physiolog. Chemie. Bd. xiii. p. 1. 
 
80 
 
 LECTUEE VI. 
 
 Gentlemen, — As you know, there is in the gastric juice and 
 glands a ferment, pepsin, the action of whicli on albuminous 
 matter will occupy us more fully. I omit to enter into the 
 methods that aim at its pure production, because none has yet 
 completely attained its object. We obtain a ferment mixed with 
 other matter when a glycerine extract of gastric mucous mem- 
 brane is treated with alcohol in excess. A white precipitate 
 falls, which on drying forms a white powder. This is soluble in 
 water, and has the characteristic pepsin action. It can be heated 
 to 100° without losing this. The preparations in common use, 
 German and French pepsin, pepsin-ptyalin, &c., are only mix- 
 tures containing more or less pepsin or ferment, albuminoids 
 and starch. I have for some years made analyses of the current 
 preparations, tested their action, and published the results; 
 therefore I will not return to the subject, as in the meanwhile 
 the articles have been greatly modified. Such analyses must be 
 repeated from time to time if we wish to estimate the value of 
 the commercial preparations. As to what we should expect, I 
 may give the statement of Petit, that active pepsin should pep- 
 tonise one thousand times its own weight of fibrine, and in seven 
 hours five hundred thousand times its weight. The best method 
 to prepare a strong peptonising fluid is by extracting the gastric 
 mucous membrane, by which means no doubt we obtain not only 
 pepsin, but also albuminous bodies and salts. We can obtain 
 a pepsin extract mixed with many other substances by carefully 
 washing the minced mucous membrane dissected off the muscular 
 coat, of a fresh pig's stomach, either by the old method given by 
 Eberle in 1834, by infusion with a three per mille solution of 
 hydrochloric acid, or, according to v. Wittich, with glycerine, or, 
 after Brlenmeyer, with a saturated solution of salicylic acid or 
 formic acid solution (1 : 1000 sp. gr. 1'205). All are very prac- 
 ticable; the best, according to my experience, being the two 
 first named. The glycerine infusion has the advantage of the 
 
PEPSIN AND PEPSINOGEN. 81 
 
 greatest strength and most easy preparation. If we want to elimi- 
 nate impure matter as much as possible, the mucous mem- 
 brane must be treated previously with strong alcohol, which does 
 not touch the pepsin, but precipitates a part of the albumen and 
 lixiviates the salts. I allow 500 ccm. of glycerine to a pig's 
 stomach. It remains in this a day until the glycerine extract 
 is active. Then it must be filtered through a fine cloth, and 
 we obtain an extract almost as clear as water, of which 
 very small quantities, a few cubic centimetres, act very 
 energetically. 
 
 C. Sundberg has obtained a very pure pepsin in the following 
 way : the mucous membrane of the stomach is extracted with 
 concentrated salt solution, the salt dialysed away into an acid 
 solution, the separated flocculi of albumen filtered off, and the 
 filtrate allowed to stand eight to fourteen days for self-digestion, 
 in order to destroy the rennet ferment, and to convert the 
 albumen present into peptone. The solution is then precipitated 
 with calcium chloride and sodium phosphate, in order to preci- 
 pitate the pepsin. The precipitate is washed, dissolved in as 
 little as possible of 5 per cent, hydrochloric acid, and the salts 
 removed by dialysis. The remainder consists of nearly pure 
 pepsin solution, which digests energetically, contains no albu- 
 minous bodies reacting to the ordinary tests, and is only precipi- 
 tated by alcohol (pepsin). Kiihne and Chittenden found that 
 ammonium sulphate precipitates not only all non-peptonised 
 albumens but also pepsin from hydrochloric acid solutions, and 
 that the pepsin may be redissolved in dilute acid, and is rela- 
 tively pure and fit for further digestive experiments. 
 
 If we wish to carry out these experiments we must remember 
 what, mutatis mutandis, we have already noted in the salivary 
 glands, and we shall have occasion to observe in the pancreas, 
 tiiat the gland cells do not form the specific ferment, pepsin, 
 but a previous stage of it, a pepsinogenous substance, pepsinogen 
 (propepsin, Schifi), which during the process of secretion be- 
 comes pepsin, so that, as Ebstein and Grutzner have found, the 
 extract of the gland cells is inactive upon albumen without the 
 addition of hydrochloric acid, but may be converted into pepsin 
 by treatment with sodium chloride or hydrochloric acid, and, as 
 Langley shows, the pepsin is destroyed by sodium carbonate, 
 while the pepsinogen is scarcely affected by it. If we extract a 
 
 6 
 
82 LECTURES ON DIGESTION. [Lect. VI. 
 
 gastric mucous membrane with glycerine the pepsin is taken 
 up, but no pepsinogen, while watery non-acidulated infusions of 
 the membrane contain pepsin and pepsinogen. 
 
 The specific action of gastric juice, or of what is the same for 
 this purpose, the pepsin or pepsin extract in acid solution, asserts 
 itself by a definite action on albuminoids, which are converted 
 into a modified form, the so-called peptone of Lehmann. The 
 tangible, practical object, if I may so express myself, of this 
 change is to form out of a little diffusible body (albumen) one 
 easily diffusible (peptone), which is capable of absorption through 
 animal membrane in a higher degree than ordinary albumen. In 
 fact, Funke has proved that the endosmotic equivalent of albu- 
 men is over 100, and that of peptone 7-1 — 9-9, that is, about 
 12 times more of the latter than of the former would pass through 
 the septum; and Acker saw that peptone solution may be 
 forced under a certain pressure more easily through an animal 
 membrane than ordinary solution of albumen. But this only 
 holds good for acid solutions of peptone, and is reversed for a 
 mixture of peptones and salts (Maly, Henninger), so that other 
 physical differences unknown to us must exist between albumi- 
 nates and peptones which occasion the undoubtedly greater 
 capacity of the latter for absorption, supposing that the selective 
 power of the epithelium of the mucous membrane is a physical 
 process and not vital. The peptonisation of albuminous bodies 
 may be brought about in the following way : if ordinary egg 
 albumen, or well-washed fibrine is put into a dilute acid solution, 
 it rapidly swells up and forms, if only a little acid has been used, 
 a compact jelly-like mass. A part of the albumen becomes dis- 
 solved as the so-called acid albumen, syntonin (Meissner's para- 
 peptone), which is a combination of albumen with the acid, and 
 may be precipitated from the acid solution by weak soda solution 
 ill the form of a white precipitate, and is called the precipitate 
 of neutralisation. In so far as this body is not changed by the 
 •pe^ptonising process about to be described it is called by Kiihne 
 ahti-albuminate. But if we add some pepsin or pepsin con- 
 taining extract to a mixture of albumen and solution of hydro- 
 chloric acid (2 — 5 per mille), and keep the mixture at the body 
 •temperature, the albumen, fibrine, &c., dissolve rapidly, the 
 fluid becomes clear, and we find at the bottom of the glass a 
 •varying quantity of undissolved albumen, according to the 
 
PEPTONE AND PROPEPTONE. 86 
 
 proportions of albumen, pepsin, and acid present. If this is 
 now filtered off we get a solution wMch contains, besides the 
 ■above described syntonin, whose amount varies with the duration 
 ■of the digestion, but finally disappears only very late, peptone 
 and the various intermediate products between native albumen 
 on the one hand and peptone on the other. The latter, which 
 are collectively described as albumoses, are a transition stage 
 between albumen and peptone. Their presence and amount 
 depend upon the duration and intensity of the fermentative 
 action. They form a series of albuminous bodies, for the know- 
 ledge of which we are indebted chiefly to W. Kiihne. Kuhne 
 divides them into protalbumose, hetero-albumose (dysalbumose), 
 deutero-albumose, antialbumide, and antideutero-albumose, of 
 which we may only state here that they are distinguished chiefly 
 by their behaviour with sodium chloride and saturated solution of 
 ammonium sulphate, their solubility in acidulated water, and 
 their coagulability by heat. But these bodies also differ by in 
 part becoming peptones, which by the action of the pancreas are 
 further split up, and in part resisting the action of the pancreas, 
 so that we shall give their features in discussing the pancreatic 
 digestion, and we may abstain from stating all their reactions, as it 
 is still an open physiological question how far they are actually 
 chemically distinct bodies, how far their differences are occasioned 
 by the varying relations between acids, alkalies, and albumoses 
 (Herth). 
 
 But I must condemn the classification based on their super- 
 ficial affinities which P. Kohmann (Anleitung zum chemischen 
 Arbeiten, Berlin, 1890) has given. The most important of these 
 bodies is the body called by Kiihne protalbumose, by Schmidt- 
 Mulheim propeptone, which is precipitated from its acetic acid 
 solution by concentrated brine or rock salt solution, which 
 becomes cloudy on slight heating, but on further heating again 
 becomes clear, so that it remains clear at temperatures which 
 coagulate native albumen, but on cooling reappears. Salkowski 
 has prepared it in a pure form and has described it as just given. 
 However, it is doubtful whether propeptone is necessarily formed 
 as an intermediate product in the gastric digestion of albumen. 
 According to the researches which Dr. Boas carried out in my 
 laboratory, it was constantly absent with purely meat food, 
 but appeared under certain circumstances with pure egg albumen. 
 
84 LECTURES ON DIGESTION. [Lbct. VI. 
 
 and was always observed in tlie digestion of fibrine. Neumeister 
 objects to these experiments, on the ground that the method 
 employed by Boas based on the above-stated properties of pro- 
 peptone (precipitation in the cold by the addition of concentrated 
 brine and acetic acid, disappearance of the precipitate on heating) 
 is not sufficient, because certain albumoses nearly allied to pro- 
 peptone (protalbumose), such as Kiihne's deutero-albumose, are 
 not excluded by it. A negative result of the above test cannot 
 prove the absence of these bodies, which can only be dis- 
 tinguished by the addition of ammonium sulphate or rock salt to 
 saturation. 
 
 I will not dispute this, indeed from a repetition of Boas' 
 experiments I can say, that when the test with brine and acetic 
 acid fails, a precipitate may be obtained with ammonium sulphate. 
 But the experiments of Boas were not concerned to prove that 
 all albumoses were absent, but that the reaction which gives 
 positive results with a certain group, the propeptones, remains 
 negative with the others ; that in the one case the conversion of 
 albumen into peptone is accompanied by the formation of pro- 
 peptones (protalbumoses), in the others it is not. 
 
 If the above described mixture, that is, a compound of albumen, 
 pepsin and a solution of hydrochloric acid of 2 — 3 parts per 
 mille, kept at the body temperature till the albumen is com- 
 pletely dissolved, or the stomach contents after ingestion of an 
 albuminous meal, be precipitated with ammonium sulphate, all 
 the' albumoses formed during digestion and not already converted 
 into peptone are thrown down, and we have in the filtrate a fluid 
 which gives all the characteristic reactions of pure peptone. 1. 
 It does not coagulate on heating. 2. No precipitate occurs on 
 saturation with sodium chloride and the addition of concen- 
 trated acetic acid, either with heat or in the cold. 3. It gives 
 a purple violet colour with copper sulphate in alkaline solution, 
 which, contrary to many statements, is distinguished very 
 sharply from the pure violet colour of ordinary soluble albumen 
 when treated in the same manner. The latter becomes purple 
 on heating only, peptone gives the colour in the cold. This 
 reaction, the so-called biuret-reaction, must be carefully con- 
 ducted with regard to the proper proportion of sulphate of copper 
 to the peptone present. If there is too little copper the reaction 
 is only seen when the first drops are added. If too much copper 
 
PREPARATION OF PEPTONE. 85 
 
 is added, and there is only a little peptone present, the reaction 
 is masked by the blue colour of the copper. It is noteworthy 
 that the biuret-reaction is obtained with propeptone as well as 
 peptone. 4. The santhoprotein reaction and the reaction of 
 Millon give a positive result. 5. With glacial acetic acid and 
 concentrated sulphuric acid the fluid becomes violet-coloured 
 and faintly fluorescent, and in a certain concentration gives a 
 band in the spectrum like that of hydrobilirubin between the 
 green and the blue. These colour reactions, given under 4 and 5, 
 are peculiar not only to peptone but to all albuminous bodies. 
 6. No precipitate is caused by addition of the following re- 
 agents, which throw down albumen and albumoses : nitric acid, 
 acetic acid, acetic acid and ferro-cyanide of potassium, acetate 
 of lead and ammonia, metaphosphoric acid, ammonium sulphate, 
 salts of the heavy metals. 7. Precipitation occurs with mercuric 
 chloride in neutral solution, hydrochloric acid and metaphos- 
 phoric acid, phosphomolybdic acid, tannic acid in weak solution 
 of acetic acid, absolute alcohol (Neumeister). 
 
 If it is desired to obtain the peptone in substance from this 
 solution it can be done, as Kiihne directs, by treatment with 
 ammonium sulphate evaporation and crystallisation, treatment 
 with absolute alcohol, boiling with hot saturated carbonate of 
 baryta solution to drive ofi" the ammonia, precipitation of the 
 barium compound of peptone by alcohol and decomposition of 
 the baryta-peptone by sulphuric acid, when we obtain a hygro- 
 scopic powder difficult to preserve in a dry state (Kiihne's 
 ampho-peptone), which possesses a nauseous bitter taste, and the 
 peculiar property when moistened with a drop of water of 
 efiervescing and evaporating like phosphoric anhydride. The 
 above-described filtrate of the digestive fluid after the precipi- 
 tation of the albumoses, contains, so soon as the digestion has 
 lasted not too short a time, still further modifications of albumen 
 which are regarded by some authors as the products of pepsin 
 action, but by Kiihne as impurities due to the mode of prepara- 
 tion of the pepsin extract from the stomach. These are leucin, 
 tyrosin, and other bodies to be afterwards described, which 
 after removal of the peptone as described, or after its precipitation 
 with alcohol, remain in the residue. Neumeister has shown that 
 a pure solution of pepsin does not give a violet colour with 
 chlorine water, showing the absence of leucin and tyrosin. 
 
86 
 
 LECTURES ON DIGESTION. 
 
 [Lect. VI. 
 
 The process of peptonisation may. be represented in the follow- 
 ing table, in which the thick brackets denote the precipitate :— 
 Albumen {i.e., fibrin, serum albumen, egg albumen, muscle albumen, 
 casein, vegetable albumen, &c.) 
 
 + 
 Gastric juice (pepsin or glycerine, &c., extract of mucous mem- 
 brane + solution of hydrochloric acid of 2 — 3 per 
 mille) 
 is kept at 37-5° and digested. The solution becomes eventually, 
 after separation of the unchanged albumen by boiling with acetate 
 of soda and acetic acid and filtering, neutralising with soda and 
 filtering again : — 
 
 Syntonin 
 
 Albumoses (proto- and deutero-albumoses [propeptone], hetero- and 
 dysalbumoses, antialbumide). 
 Treated with concentrated ammonium sulphate solution, or 
 saturated with powdered ammonium sulphate, or rock salt, and 
 brine-saturated acetic acid added drop by drop: — 
 
 Albumoses 
 
 Treated with absolute alcohol, or after Kiihne's above-described 
 method : 
 
 Peptone (amphopeptone) 
 
 Leucin, Tyrosin, &c. 
 
 For the pure preparation of peptone it is naturally of the 
 greatest importance that the materials used should be as far as 
 possible chemically pure. This is not the case in our ordinary 
 digestion experiments, and is only under special provisions 
 possible, of which in the above description, which only gives the 
 general outline of the chemical relations, no mention is made. 
 
 Pure peptone is so difficult to prepare that the various workers 
 who have investigated this body have described quite different 
 
COMPOSITION OF PEPTONE. ,87 
 
 bodies as pure peptone, and have given correspondingly diverse 
 definitions of it. 
 
 It can have no interest for us to recall the history of these 
 well-worn investigations. Eecently Maly, Henninger and 
 Herth, Kossel, and especially Kiihne with his pupils Chittenden 
 and Neumeister, have claimed to have actually prepared pure 
 peptone. However, the first three authors have not obtained pure 
 peptone, but only albumoses. This is shown not only by the 
 large amount of carbon which their analyses give, namely, 51-58 
 per cent. (Henninger) and 5r40 per cent. (Maly) against the 
 carbon in fibrin, 52-51 per cent., but also from the statement of 
 Maly, that his solution of peptone in acetic acid solution becomes 
 cloudy, or is precipitated on the addition of yellow prussiate of 
 potash, whilst it is now universally recognised that a digestive 
 product is peptone only when the reactions of albumen and albu- 
 mose no longer occur. In fact, the figures which Kiihne and 
 Chittenden have obtained as a mean of five analyses for hemi- 
 albumose without ash formed from fibrin — 
 
 C = 51-14 
 H= 6-67 
 N = 16-86 
 closely resemble those found by Maly and Henninger in their 
 so-called peptone ; whilst Kossel for fibrin peptones and Kiihne 
 and Chittenden for the so-called amphopeptone (see later under 
 pancreatic digestion), a product of prolonged pepsin digestion, 
 found the following as a mean of ten analyses : — 
 
 Kossel. KUhne and Chittenden. 
 
 C = 48-97 C = 48-47 
 
 H= 7-06 H= 7-02 
 
 N = 15-14 N= 16-86 
 
 S = 1-16 S = 0-77 
 
 These analyses give a much smaller amount of carbon than is 
 
 present in fibrin (0 = 52-51, H = 6-98, N = 17-34), and was 
 
 present in the substances described as peptone. 
 
 According as peptone is formed from casein, fibrin, or serum 
 albumen, slight differences are to be observed in its relation to 
 polarised light, which all peptone solutions rotate to the left. 
 The body prepared by Henninger was white, amorphous, easily 
 pulverised, destitute of smell and taste, dried at 118°, and at 
 160° to 180° was decomposed into water and foul-smelling 
 
88 LECTURES ON DIGESTION. . [Lbct. VI. 
 
 gases. It dissolved in water and acetic acid, and gave tte 
 above-named reactions. The peptone prepared by Kuhne was 
 a loose yellow powder, wbich assumed a constant weight at 105°, 
 and possessed the above-described properties. 
 
 What, then, are these peptones? What position do they 
 occupy among the albumens ? 
 
 Adamkiewicz has endeavoured to maintain, on the basis of a 
 very able investigation, that chemically they are nothing but 
 albuminates, which diifer from the ordinary albumens by con- 
 taining rather fewer salts, and by their somewhat diiferent 
 molecular composition. But he, like his predecessors, only had 
 propeptones before him, so that his opinions and conclusions fall 
 to the ground. 
 
 To a similar conclusion, based apparently upon the investigation 
 of a purer material, comes A. Poehl. According to him, peptone, 
 by treatment with alcohol or alcohol-ether, gives some of 
 the characteristic reactions of albumen prepared from fibrin 
 and no changes of rotatory power or of refraction. As an 
 important alteration in the atoms of the molecule without in- 
 fluencing its optical relations is inconceivable, Poehl believes 
 that we must discard the idea of a chemical change in albumen 
 as a consequence of peptonisation, and he accepts the " swelling 
 theory," according to which the change of albumen into peptone is 
 conditioned simply by diflferent degrees of solubility and capacity 
 for swelling. Admitting that Poehl really worked with pure 
 peptone, which, so far as my information goes respecting this 
 Dorpat thesis, is not certain, the entire " swelling theory " is en- 
 cumbered by many improbabilities, and it is not thoroughly 
 established that the changes of molecular structure are always 
 accompanied by changes in optical relations, or that, on the 
 other hand, bodies with equal rotatory power must have always 
 the same arrangement of the atoms in the molecule. Thus, 
 grape sugar, freed from water, rotates, according to Tollens, 
 +53°1, that containing water only -|-48°27, and yet Niemand 
 holds that the arrangement of the atoms in the molecule in both 
 cases is not identical. 
 
 Most workers, especially Hoppe-Seyler and Danilewski, as 
 well as Neumeister, take the view that first albumose and then 
 peptone are formed from ordinary albumen by the addition of 
 water, and that these bodies arise in the same way as, for example. 
 
POSITION OF PEPTONES. 89 
 
 grape sugar from starch, with the difference which the albimiens 
 derive from the digestion, that the hydration proceeds from the 
 splitting up of the albumen. Henninger has proved this directly 
 by comparing the composition of his peptone with the original 
 albumen ; and, in fact, he has performed the experimentum crucis, 
 by reconverting his. peptone by dehydration (boiling with acetic 
 acid anhydride at 80°) into a body which had all the properties 
 of syntonin, that is, of the next modification of albumen. Hof- 
 meister attained the same end by heating fibrin peptone to 
 140° — 170°, and Kjukenberg and Neumeister converted fibrin 
 and albumen into albumoses and peptones by the action of 
 high-pressure steam. So that here we have an illustration of 
 the description given in the first lecture of the action of fer- 
 ments, namely, that of constituting a sort of Bunsen's flame in 
 the organism. In fact, there can now be no doubt that peptones 
 (not only by analogy, as Bunge wrongly believes, but proved by 
 experiment) are to be considered the hydrates of the albuminates. 
 
 This follows from the facts which may be here recapitulated : 
 1. Peptones contain less carbon and nitrogen than albumens. 2. 
 They are reconverted into albumen by dehydrating substances. 
 3. The conversion of albumen into peptone is accompanied, as 
 Danilewski has shown, by an increase of weight, which is only 
 possible by the addition of water. Finally, it may be stated that 
 B. Danilewski found the specific heat of (pure ?) peptone to be 
 5334, 4876, and 4997 calorics for 1 of material, that is, less 
 than that of the albumens. 
 
 You see, gentlemen, that peptone, in course of time, has got 
 on badly. After having disputed for so long what peptone was 
 or was not, they have not only taken from it its greater diffusi- 
 bility, which was so important for the question of absorption and 
 for the object of peptonisation, but they now deny that there is 
 any important structural alteration in it as opposed to native 
 albumen. Indeed, it remains doubtful, as we shall see later on 
 (Lecture XI.), whether, in fact, peptone or its earlier stages, 
 the albumoses, is absorbed. 
 
 During digestion the gastric mucous membrane is more or less 
 saturated with peptone, and, according to Hofmeister, appears 
 to be modified thereby in a peculiar way. If we divide in two 
 nearly equal parts the stomach of a recently killed digesting dog, 
 and examine the first at once and the second after a lapse of 
 
90 LECTURES ON DIGESTION. [Lect. YI. 
 
 time, about two hours, we find in the last much less peptone than 
 in the first, so that Hofmeister believes that this loss is brought 
 about by a vital action of the surviving mucous membrane, but 
 it is not known what has become of the peptone which has dis- 
 appeared, or what has happened to it. 
 
 If peptone is injected into the blood in large quantities it 
 causes a toxic depressing effect on the central nervous system, 
 and after some sleepiness and somnolence may lead to the de^th 
 of the animal. This, perhaps, explains the sleepiness that occurs 
 after heaivy meals, that is, after the introduction of a large 
 quantity of peptone into the blood ; but we shall return to this, 
 as well as to the subject of the channels by which peptone leaves 
 the stomach or intestine, in the chapter on absorption. 
 
 Another remarkable property of peptone is, that when introduced 
 in small quantities into the circulation it destroys or delays the co- 
 agulability of the blood by dissolving the white blood corpuscles, 
 and lowers the blood pressure so as to kill the animal. However, 
 this property is not peculiar to it, as Kiihne-Pollitzer and Neu- 
 meister have obtained the same result with the different albumoses, 
 and, according to the experiments of Professor Salvioli, of Genoa, 
 the diastatic ferments exert the same influence. An extract 
 may be made from leeches, as Haycraft has shown, which, when 
 injected into the living blood, or added to that obtained by 
 venesection, delays coagulation for a long while. In all these 
 instances we have to do with the toxic action of a ferment, which, 
 by the destruction of numerous leucocytes, makes the blood more 
 or less incapable of coagulating, so that the action of peptone 
 must be regarded as only an illustration of a general process. 
 
 Finally, we must refer to the bitter taste of all peptone solu- 
 tions, because the intensely bitter taste of vomited matter, which 
 we always used to attribute to the bile mixed with it, is in all 
 probability, as 0. Liebreich first suggested, caused by peptone. 
 
 Besides its peptonising property, gastric juice, as you know, 
 also possesses that of effecting the curdling of milk. In the 
 preparation of whey, this has the most extensive employment, 
 as the so-called rennet is nothing but gastric juice, or rather 
 gastric juice imbibed by the gastric mucous membrane. Ham- 
 marsten has succeeded in isolating from gastric juice a body 
 differing from pepsin, which affects the coagulation of milk in 
 neutral or acid solutions without changing the reaction. He 
 
THE RENNET FERMENT. 91 
 
 describes it as the rennet ferment. According to the suggestion 
 of Langley, and the more recent researches of Klemperer and 
 Boas, there is also an early stage of this ferment, a proenzyme or 
 rennet zymogen, out of which is suddenly formed the specific 
 rennet ferment, just as pepsin is formed from pepsinogen. But 
 the rennet ferment may be extracted from the gastric mucous 
 membrane by the action of hydrochloric acid ; and quite in opposi- 
 tion to one's expectations, in the newly-born, for whom it is so 
 much needed, it is found to be present, but by no means in greater 
 quantities than elsewhere. Its presence in the gastric juice is 
 demonstrated by the coagulation of milk, arid its separation into 
 curd and whey when equal parts of neutrally reacting and filtered 
 milk and carefully neutralised gastric juice are kept at the tem- 
 perature of the body for from ten to fifteen minutes. The 
 ferment is killed by the addition of alkaline carbonates. If the 
 reaction is acid, peptic digestion takes the place of the curdling 
 process. If the stomach contents contain only rennet zymogen, 
 and coagulation does not occur with the above-described treat- 
 ment, the zymogen may be converted into ferment by the 
 addition of dilute hydrochloric acid or a five per cent, solution of 
 calcium chloride. At the commencement of digestion, and during 
 fasting, only the proenzyme is present in the glands or in their 
 secretion, which obviously becomes converted into the ferment 
 as secretion of acid increases. But in milk there is milk sugar, 
 which by treatment with gastric juice is partly converted into 
 lactic acid, and remains unchanged when treated with Hammar- 
 sten's rennet ferment ; so we _ have nothing to oppose to the 
 further conclusion of Hammarsten, that besides the "rennet 
 ferment" there also exists in the gastric juice a "lactic acid 
 ferment," especially as Bllenberger and Hofmeister state that 
 they have been able to extract from the stomach of the horse 
 both rennet ferment and the lactic acid ferment. There still 
 remains the question whether, in this case, they had to do with 
 a pre-existing ferment, or with the action of an accidentally 
 present lactic-acid-forming micro-organism. I have made some 
 experiments with Dr. Boas by introducing starch solution or 
 sugar (maltose) into the clean, well-washed stomach of a healthy 
 man, and no lactic acid was formed. Dr. Rosenheim has con- 
 tested this result, but recent experiments have confirmed our 
 statement that in many cases no formation of lactic acid takes 
 
92 LECTURES ON DIGESTION. [Lbct. VI. 
 
 place, and that where it occurs pathological conditions are 
 present, though not such as need give rise to any subjective 
 symptoms of ill-health in the individual concerned. 
 
 The action of the gastric juice or acid pepsin, solutions should 
 be, according to the theory of ferments, quite endless— that is, they 
 should be able to convert any quantity of albumen into peptone. 
 But this is not the case. In an artificial digestive mixture, the 
 process comes to an end after a certain time, before all the 
 albumen is digested, by the accumulation of the products of fer- 
 mentative action, as already explained. We must then add more 
 acid, or dialyse away these products. In what manner the acid is 
 utilised has not been hitherto satisfactorily explained. According 
 to Hoppe-Seyler, it forms acid compounds with the albuminoids 
 present (syntonin and peptone). At length the addition of acid 
 no longer helps in the digestion of further quantities of albumen ; 
 the pepsin becomes inactive, probably decomposed. The necessary 
 quantity of pepsin, compared to the quantity of albumen finally 
 digested, is always surprisingly small, and this circumstance 
 supports the belief that pepsin is a true ferment, in spite of 
 the theoretical claims being, as we saw, incompletely satisfied. 
 This is the place to say a few words respecting the much- 
 discussed " loading " theory of Schiff, which, though not tenable 
 in its original shape, has obtained some support from experiments 
 of Herzen, which should not be too lightly appreciated. Schiff 
 believed that the formation or secretion of pepsin depended 
 upon the introduction into the stomach of certain " peptogens " ; 
 for example, meat, bread, bone, dextrine, &c., and the glands 
 were to some extent first "loaded," according to the claims 
 made by the food taken. The grounds on which the Genevese 
 physiologist rested cannot stand stringent criticism, and the 
 differences in the amount of pepsin present in the various 
 stages of digestion which Schiff found may well have been due 
 to the greater or less amount of propepsin converted into pepsin. 
 But as a matter of fact, the food present is not without its 
 influence on the rapidity of the digestion of albumen, as was 
 shown by Herzen in a most demonstrative way at the Congress 
 of Naturalists at Strasburg (1885). He had introduced into 
 the stomach of a patient with a gastric fistula little muslin 
 bags containing cubes of albumen about the size of hazel-nuts, 
 and after different periods of duration in the stomach these were 
 
HYDROCHLORIC ACID IN DIGESTION. 93 
 
 withdrawn. The cubes were found to be eaten away in pro- 
 portion to the time they had remained in the stomach, and 
 when placed in a row made a graduated series like a row of 
 organ pipes. But if dextrine or meat soup, the principal 
 representatives of SchifFs peptogens, were previously introduced 
 into the stomach, the erosion of the cubes occurred much more 
 rapidly, as was easily to be recognised on. comparing them with 
 the former series. 
 
 I must confess that neither this nor Schiflf's earlier statements 
 are surprising, and that they may be better ascribed to a previous 
 secretion of pepsin and hydrochloric acid than to a special 
 "loading" of the glands. We have found that the instant 
 after the introduction of starch solution into the stomach free 
 hydrochloric acid and pepsin make their appearance. This 
 naturally also occurs with SchiS's peptogens, and the subsequent 
 digestion finds ready for it a considerable quantity of hydro- 
 chloric acid and pepsin, and can consequently exert a far more 
 energetic action. 
 
 The necessary amount of hydrochloric acid in digestive fluids 
 fluctuates within proportionately wide limits, and lies between 
 O'l and 5 — 7 per cent. Moreover, it is not equal for all kinds of 
 food, as we know from the researches of Wawrinsky and Briicke. 
 Fluid albumen is more difficult to digest in feebly acid fluids 
 than solid albumen, whilst the reverse occurs with higher 
 (normal) degrees of acidity. Casein is more easily dissolved 
 than fibrin, the latter more easily than egg albumen, animal 
 albumen more easily than vegetable albumen, differences which 
 obviously depend upon the difierent capacities of these substances 
 for imbibing hydrochloric acid. Fibrin, for example, when 
 put into hydrochloric acid rapidly becomes a white jelly-like 
 mass, while boiled albumen only becomes transparent in its 
 outer layers and swollen. In this way pepsin takes very 
 difierent periods to liquefy difierent kinds of albumen. Blondlot 
 saw that a dog with a gastric fistula digested 100 grms. of 
 boiled albumen in five hours, and 100 grms. of albumen beaten 
 to a froth in three-and-a-half hours. Ufielmann gave a boy 
 with a gastric fistula a solution of albumen and water, and 
 could prove the existence of peptone after twenty minutes,; 
 therefore the statement that hard-boiled eggs are digested 
 better than soft, certainly originates in error. Wherever albu- 
 
94 LECTUEES ON DIGESTION. [Leot. VI. 
 
 minoids are taken as constituents of our complexly-formed 
 nutriment, their rapidity of digestion depends naturally entirely 
 upon the condition of the nutriment, that is, its accessibility to 
 the gastric juice. Here is a table in which you will find these 
 conditions arranged, as they are of the highest importance to 
 us as practitioners. (See the end of this lecture.) We know 
 besides that we can digest artificially not only with hydrochloric 
 acid, but also with phosphoric acid, sulphuric acid, acetic acid, 
 and lactic acid, but that the active degree of acidity varies with 
 the acid employed. Davidson and Dieterich in 1860 showed by 
 comparative observations that the same digestion requires with 
 lactic acid about six times higher acidity than with hydrochloric 
 acid, and about half as much again as with acetic acid ; 100 grms. 
 of fresh gastric juice dissolve 5 grms. of dried albumen, according 
 to Lehmann; according to Bidder and Schmidt, 2-2 grms.; 
 according to Oorvisart, 4'9 grms. 
 
 It is not unimportant to remark with reference to the recently 
 much-discussed question of the presence or absence of free hydro- 
 chloric acid in cancer of the stomach, that free acid is not 
 necessary to peptic digestion, but that the acid imbibed by 
 the albumen suffices. In my above-quoted work on the co- 
 efficient of partage, I have related some experiments which 
 prove this beyond doubt. If, for example, we wash some fibrin 
 and hydrochloric acid jelly with water until the acid reaction 
 disappears, and then add to it some glycerine stomach extract, 
 we get a peptonisation of the fibrin, which, if not so productive 
 as in the presence of free acid, yet removes all objection to the 
 above statement. A. Herzen has arrived at the same result in 
 another way by introducing pieces of albumen through a gastric 
 fistula. Neutralisation of the gastric juice or admixture of 
 bile stops digestion. The latter, according to Burkart, forms 
 a precipitate by means of the bile acids, which mechanically 
 throws down the pepsin; certainly it would need for that a 
 great quantity of bile. A little bile allows the digestion to 
 <!ontinue, as you may perceive here. In the earlier editions 
 of these lectures I wrote : "It appears to me doubtful whether 
 the entrance of bile into the duodenum at once stops the pepsiii 
 digestion in the chyme ; at any rate, small quantities of bile 
 •easily find their way into the stomach, as I have often ob- 
 served, without efiect on the gastric digestion." Since then 
 
INFLUENCE OF DRDGS, ALCOHOL, ETC., ON DIGESTION. 95 
 
 Boas has directly confirmed this statement by obtaining bile 
 from living men by manual expression (massage) of the 
 duodenal contents into the stomach, and thence withdrawing 
 it by a tube and mixing it with digesting stomach contents. 
 In the mixture of gastric and intestinal juice, a thick copious 
 precipitate is formed, but the supernatant fluid exhibits as 
 before good peptic digestibility. The gastric digestion is 
 hindered or prolonged by all salts of the heavy metals (acetate 
 of lead, mercuric chloride, &c.) ; hence the well-known rule 
 to administer these considerably before or after meal-times. 
 The influence of preparations of iron is an extremely important 
 chapter in therapeutics, because we so often have to order iron 
 in affections of the stomach ; it has been studied by Diisterhoff, 
 and the empirical doctrine that salts of iron interfere with 
 digestion confirmed by him, with the limitation that this occurs 
 less with the proto salts than with the per salts. Salicylic acid, 
 alcohol, carbolic acid, and concentrated solutions of alkalies, have 
 a similar influence, because, partly by irritating the mucous 
 membrane, they give rise to an alkaline transudation into the 
 stomach. Of much importance is the action of alcoholic drinks, 
 the consumption of which, especially of beer, has lately increased 
 so alarmingly. Different investigators — Klikowicz, Bikfalvi, Ogata, 
 Schellhaas, Schiitz— have come to the conclusion, partly by arti- 
 ficial digestion, partly by observations in cases of fistula, partly by 
 experiments made with this object on healthy men, that alcoholic 
 drinks retard digestion, although they are rather at variance as to 
 the required dose of alcohol, inasmuch as some (Ogata, Bikfalvi, 
 Schiitz) put it at 2 per cent., the others at 10 per cent, and more. 
 However, wine even in relatively large quantities (Schellhaas per- 
 mits half a litre of wine to be taken at dinner) interferes with 
 digestion very little or not at all. The worst enemy of digestion 
 is schnaps, or spirits; if it apparently does good, it does 
 so only because the brain is deceived by the alcohol as to the 
 state of the stomach. Upon the action of neutral salts, which 
 on account of their presence in the various mineral waters have 
 no slight importance for the question of gastric digestion, we 
 have recently had a series of experiments with artificial diges- 
 tive mixtures, according to which they are all at least not 
 favourable. E. Pfeiffer says that digestion proceeds best with- 
 out the addition of any salt ; it is least controlled by sulphate 
 
96 LECTURES ON DIGESTION. [Lect. VI. 
 
 of magnesia and sulpiiate of soda, mucli more by carbonate and 
 chloride of sodium. Herzen came to an equally unfavourable 
 conclusion as to the effect of chloride of sodium in his gastro- 
 tomised patient (v. supra, p. 92), as he found in two series of 
 experiments, which in each case lasted six or seven days, that 
 the amount of hydrochloric acid in thb gastric juice, without 
 the addition of salt to the food, amounted to 3-14 per mille, 
 with salt in doses of 5, 40, and 20 grms; it fell to 1"26 per mille. 
 
 In the results of such experiments, which we must accept 
 " cum grano sails,'' much may be due to the reciprocal relations 
 of the bodies present in the digestive mixture and their degree 
 of concentration, which in the human stomach must be changing 
 from minute to minute by the process of absorption. Therefore 
 on these grounds it would be quite a mistake to find any 
 serious objections to the use of certain springs like Wiesbaden, 
 Kissengen, Carlsbad, &c., whose beneficial action on gastric 
 digestion is notorious. Moreover, in these cases the water is 
 not taken with food, their relations are obviously quite dif- 
 ferent, and are not at all elucidated by such experiments. The 
 much-prized bitters and carminatives, according to Buchheim, 
 and according to the more recent experiments of Tschelzoff and 
 Jaworski, do not further digestion ; but spices, on the contrary, 
 as is well known, stimulate secretion. Reichmann has so far 
 modified this statement, that bitter infusions taken during 
 digestion inhibit it, but given on a fasting stomach they lead, 
 after the remedy has disappeared, to an increased secretion 
 with the following supply of food, so that bitters should be 
 taken about half an hour before a meal. Heating destroys the 
 action of the gastric j nice, but freezing does not. However, gastric 
 juice may be slowly dried at 50° — 55° C. without the residue 
 when taken up with water having lost any of its peptic power. 
 The digestive mixture which I show you now was prepared with 
 a glycerine extract so treated. You gee in the filtered solution 
 the characteristic reaction of peptone, and perceive besides that 
 even higher temperatures, as previously 'described, do not make 
 the ferment inactive. 
 
 Finally, just a word or two on the seat of secretion in the 
 stomach, that is to say, whether the fundus only or the pyloric 
 region also secretes active juice. There has been a. great dis- 
 pute waged on this subject, which we happily can pass over, 
 
FUNCTION OF THE CELLS. 97 
 
 because it is decided by the following experiment of Heidenhain's : 
 separate the entire pyloric region, preserving the mesentery and 
 vessels from the stomach, bring together the remainder of the 
 stomach and the duodenum, and form a sort of pouch in the 
 abdominal wall out of the separated piece. In the dogs which 
 survive this terrible operation, there forms a fistula which secretes 
 a thick hyaline mucus, which, treated with O'l per cent, of hydro- 
 chloric acid, digests fibrin vigorously, and curdles milk without 
 forming any acid. But, as you may perhaps recollect, the pyloric 
 glands possess only the " so-called central cells"; so this experi- 
 ment pleads in favour of the view many times disputed, which 
 Heidenhain has supported by other arguments and by the micro- 
 chemical relations of the cells and their different resistance to 
 dilute hydrochloric acid, that we have in the central cells the 
 pepsin-secreting, and in the parietal cells the acid-secreting part 
 of the gland. The thick mucus which covers the surface of the 
 stomach is derived, especially in the pyloric region, from a 
 mucous metamorphosis of the epithelium. 
 
 Swiecicki and Sehrwald have given further support to Heiden- 
 hain's view of the function of the different kinds of cells. The 
 former showed that in the stomach of the frog, which possesses 
 only parietal cells and no central cells, which latter are only 
 found in the lower part of the pylorus, pieces of meat soon give 
 an acid reaction, but are not digested if the oesophagus is tied. 
 Sehrwald utilised the property of the protosalts of iron to form 
 Tumbull's blue with ferricyanide of potash in acid solutions. 
 If fresh pieces of the gastric mucous membrane were put in such 
 a mixture, the parietal cells became stained a beautiful dark blue, 
 while the central cells inside the glands remained colourless, only 
 the layer lying close under the surface of the mucous membrane 
 showed sometimes a slight blue border, probably in consequence 
 of the entrance of acid gastric juice, in fact, a commencement 
 oi 'post mortem digestion. 
 
98 
 
 LECTURES ON DIGESTION. 
 
 [Lbct. VI. 
 
 Table of Gastric Digestion. 
 
 Pood arranged according 
 to thetime required for 
 digestion in the stomach. 
 
 Mode of 
 preparation. 
 
 Duration in stomach till solution or 
 disappearance. 
 
 Sohnaps 
 
 Milk 
 
 Cauliflower 
 
 Cane sugar 
 
 Bullocks' tripe . . . 
 
 J'igs' feet 
 
 -— Eice 
 
 Peas with butter 
 
 Baked potatoes 
 
 Whipped eggs ... 
 
 Barley broth . . . 
 
 Salmon trout . . . 
 "Bipe apple 
 
 Meat (?) 
 
 - Venison 
 
 Calves' brains ... 
 
 Beaumont. 
 
 Sago 
 
 Spinach 
 
 Maccaroni with fat 
 -Eggs 
 
 Milk 
 
 Bread 
 
 Salad 
 
 Soup with fat and bread 
 
 Eice with fat 
 
 Lentils with egg 
 
 Bullocks' liver 
 
 - Turkey 
 
 -Pork 
 
 -Lamb 
 
 -Beans 
 
 -Potatoes 
 
 -Cabbage 
 
 ■ Cauliflower with fat . . . 
 
 Eice with fat and wine 
 
 Maccaroni with fat ... 
 
 ' Oysters 
 
 -button 
 
 roasted 
 boiled 
 
 raw 
 boiled 
 
 boiled 
 
 raw 
 
 ?j 
 baked 
 raw 
 boiled 
 
 raw 
 
 roasted 
 
 boiled 
 
 raw 
 stewed 
 
 Ih 
 lb 
 Ih 
 
 IhSO' 
 lh30' 
 lb 30' 
 IhSO' 
 
 lh45' 
 lh45' 
 lb 45' 
 
 2h 
 2h 
 2h 
 2h 
 
 2hl5' 
 2h25' 
 2h30' 
 2h30' 
 2h30' 
 2 b 30' 
 2h30' 
 
 3h 
 3h 
 
 Eiohet. 
 30' to 40' 
 30', 1 h 
 
 1— 2h30' 
 Ih,2hl5',2h30',8h 
 
 Ih30',2h30',4h,5h30' 
 
 lh45', 2h, 4h 
 
 1 h 45', 2 h 30', 3 h 15' 
 
 2h 
 
 2h,2h45',3h,3hl5' 
 2h, 2h45' 
 
 2h 
 2h30' 
 
 2 h 30', 2 h 45' 
 2h30' 
 2h30', 3h45' 
 
GASTRIC DIGESTION. 
 
 99 
 
 Table of Gastric Digestion — (continued.) 
 
 Food arranged according 
 to the time required for 
 digestion in the stomach. 
 
 Mode of 
 preparation. 
 
 Duration in stomach till solution or 
 disappearance. 
 
 -Soft eggs 
 
 Beef- steak 
 
 'Ham 
 
 Lean bacon 
 
 White bread 
 
 -Fish 
 
 Onion soup 
 
 Eggs with sugar 
 
 Pork 
 
 Poultry 
 
 Veal and Bacon 
 
 Black bread 
 
 Cartilage 
 
 Cabbage 
 
 Pork 
 
 , Hard eggs 
 
 boiled 
 
 boiled 
 fried 
 baked 
 boiled 
 
 roasted 
 
 baked 
 boiled 
 
 )) 
 salted 
 boiled 
 
 Beaumont. 
 3h 
 3h 
 3h 
 3h 
 3h 
 3h 
 
 4h 
 4h 
 4h 
 4h 
 4h 
 5h 
 5h 
 5h 
 
 Eichet. 
 
 8h 
 3h30' 
 
 The statements in these tables are derived from two cases of 
 gastric fistula. The first is the famous Canadian, St. Martin 
 (observed by Dr. Beaumont), who had a fistula in consequence of 
 a gun-shot wound. The second had an impermeable stricture of 
 the oesophagus, resulting from cicatricial contraction after swal- 
 lowing caustic potash. He was gastrotomised by Verneuil, and 
 afterwards observed by Richet. He obtained food by its being 
 injected through the fistula. The statements in the cases recorded 
 by Schroder, Grunewald, Kretschy, and Uffelmann, are too in- 
 exact to be included in this table. The following data, prepared 
 by Dr. Gigglberger, under the direction of Penzoldt, are much 
 more valuable. After lie had ascertained that his digestion was 
 thoroughly normal, he tested the time required for the digestion 
 of various meats by introducing a tube into his stomach every 
 quarter-of-an-hour after a meal and expressing a small quantity 
 of the contents. When the stomach appeared to be empty this 
 was determined beyond doubt by washing it out. 
 
100 
 
 LECTURES ON DIGESTION. 
 
 [Lect. vr. 
 
 Animal. 
 
 Part. 
 
 Preparation. 
 
 Weight. 
 
 Time. 
 
 1 
 
 veal 
 
 brains 
 
 boiled 
 
 250 
 
 2-55 
 
 2 
 
 — 
 
 It 
 
 >> 
 
 » 
 
 2-30 
 
 3 
 
 — 
 
 ii 
 
 baked 
 
 j» 
 
 3-05 
 
 4 
 
 — 
 
 sweetbread 
 
 boiled 
 
 j> 
 
 2-30 
 
 5 
 
 — 
 
 joint 
 
 roast 
 
 It 
 
 3-00 
 
 6 
 
 — 
 
 It 
 
 jj 
 
 rt 
 
 3-55 (3-30) 
 
 7 
 
 — 
 
 feet 
 
 boiled 
 
 tt 
 
 3-50 
 
 8 
 
 beef 
 
 joint 
 
 raw 
 
 tt 
 
 3-15 
 
 9 
 
 — 
 
 )» 
 
 It 
 
 tt 
 
 3-00 
 
 10 
 
 — 
 
 It 
 
 boiled 
 
 tt 
 
 3'30 
 
 11 
 
 — 
 
 if 
 
 »j 
 
 j» 
 
 4-40 
 
 12 
 
 — 
 
 »» 
 
 roast 
 
 160 
 
 3-15 
 
 13 
 
 — 
 
 loin 
 
 )> 
 
 225 
 
 4-00 
 
 14 
 
 — 
 
 ji 
 
 tt 
 
 250 
 
 3-45 
 
 15 
 
 — 
 
 j> 
 
 beefsteak 
 
 iy 
 
 3-50 (2-50) 
 
 16 
 
 — 
 
 tongue 
 
 boiled 
 
 jj 
 
 3-05 
 
 17 
 
 — 
 
 M 
 
 >) 
 
 *f 
 
 3-40 
 
 18 
 
 
 »» 
 
 tt 
 
 T1 
 
 5-00 
 
 19 
 
 
 M 
 
 smoked 
 
 ft 
 
 4-15 
 
 20 
 
 mutton 
 
 joint 
 
 roast 
 
 210 
 
 3-30 
 
 21 
 
 pork 
 
 »» 
 
 fj 
 
 170 (!) 
 
 4-00 (3-30) 
 
 22 
 
 — 
 
 It 
 
 » 
 
 160 (!) 
 
 2-30 
 
 23 
 
 — 
 
 ham 
 
 scraped raw 
 
 160 (!) 
 
 3-00 (2-30) 
 
 24 
 
 — 
 
 j» 
 
 tt 
 
 160 (!) 
 
 3-10 
 
 25 
 
 — 
 
 »f 
 
 raw 
 
 160 (!) 
 
 4-15 
 
 26 
 
 — 
 
 )» 
 
 boiled 
 
 160 (!) 
 
 3-00 
 
 27 
 
 hare 
 
 back 
 
 roast 
 
 250 (!) 
 
 3-40 
 
 28 
 
 — 
 
 »j 
 
 tt 
 
 250 (!) 
 
 4-25 
 
 29 
 
 chicken 
 
 — 
 
 boiled 
 
 220 (!) 
 
 2-45 (2-20) 
 
 30 
 
 — 
 
 — 
 
 roast 
 
 230 
 
 3-05 (2-35) 
 
 31 
 
 partridge 
 
 — 
 
 3» 
 
 240 
 
 3-30 (2-30) 
 
 32 
 
 pigeon 
 
 — 
 
 boiled 
 
 220 
 
 3-35 
 
 33 
 
 — 
 
 — 
 
 9) 
 
 260 
 
 3-00 
 
 34 
 
 — 
 
 — 
 
 roast 
 
 195 
 
 3-10 
 
 35 
 
 — 
 
 — 
 
 tt 
 
 210 
 
 3-50 
 
 36 
 
 duck 
 
 — 
 
 )» 
 
 280 
 
 4-15 
 
 37 
 
 goose 
 
 
 »> 
 
 250 
 
 4-00 
 
 N.B.— The figures in brackets signify the time at which the muscular 
 fibres had disappeared from the contents of the stomach. 
 
 Naturally, such observations give only approximate data. "We 
 can easily see from Eichet's table, where the same article of food 
 was digested several times, how different may be the period of its 
 
BIBLIOGRAPHY. 101 
 
 duration in the stomach; but we know also how much the diges- 
 tion is dependent upon general conditions, psychical influences, 
 &c. Richet justly remarks : " Nul organe, peut-6tre, n'est aussi 
 fantasque dans sa fonction que I'estomac.'' 
 
 Eberle. Physiologie der Verdaurmg. Wiirzburg, 1834, p. 122. 
 
 V. Wittich. XJeber eine neue Methode zurDarsteUung kttnstliolier Verdanungs- 
 
 flUssigkeiten. Pflilger's Archiv. Bd. li. p. 192. 
 Erlenmeyer. Darstellnng der ungeformte Fermente. Munohener Sitzgsber. 
 
 mathem. physical. Classe. 1875, Hft. 1, and Ztsohrft. f. analyt. Clieinie,Bd. xv. 
 
 p. 426. 
 Fanke. Das endosmot. Verhalten der Peptone. Virohow's Archiv. Bd. liii. 
 
 p. 449. 
 Adamkiewicz. Natur iind Nahrwerth der Peptone. Berlin, Hirschwald, 1878. 
 Henninger. De la natare et du rSle physiologiqne des peptones. Paris, 1878. 
 Hofmeister. ITeber die Eilckbildung von Biweies ans Pepton. Ztscbrft. f. phy- 
 
 siolog. Chemie, Bd. ii. p. 206. 
 Hammarsten. Ueber die Milchgerinnerung und die dabei wirkenden Feimente 
 
 der Magenschleimhaut. Jahraber. f . Thierohemie fur 1872, p. 118. 
 Blondlot. Traite' analytique de la digestion, p. 270. 
 USelmann. Loc. cit. 
 Heidenhain. Ueber die Pepsinbildung in den Pylornsdrilsen. PflUger's Archiv. 
 
 Bd. xviii. p. 122. 
 Wawrinsky. TTeber die Loslichkeit des geronnenen und flussigen Eiweiss im 
 
 Magensaft. Jahrsber. f. Thierohemie, 1673, p. 178. 
 Ebstein and Griitzner. Ueber Pepsinbildung im Magen. Pfluger's Archiv. 
 
 Bd. viii. p. 122. 
 Witt. Einige Unteranchnngen ilber den Ursprung des Pepsin. Jahrsber. f. 
 
 Thierohemie, 1875, p. 160. 
 W. Kixhne. Albumosen und Peptone. Verhandl. des natnrhistor. med. Vereins 
 
 zu Heidelberg, N. P. 3, p. 286. 
 W. Kiihne's Arbeiten in Zeitschr. f. Biologic. N. F. Bd i. et seq. 
 W. Kiihne and Chittenden. Zeitschr. f . Biologic. Bd. 92. 
 Neumeister. Ueber die Eeaotionen der Albumosen und Peptone. Ueber die 
 
 nachste Einwirkung gespannter Wasserdampfe anf Proteine and other Essays 
 
 in Zeitschr. f. Biologic. N. P. Bd. vii. et seq. 
 Neumeister. 1. Zur Prage nach dem Schicksal der Eiweissnahrung im Organis- 
 
 mus. 2. BeitrSge zur Chemie der Verdauungsvorgange. Wurzburger Sitzungs- 
 berichte, 1889. 
 Petit. Etude sur les ferments digestifs. Joum. de Th^rap., 1880. 
 Langley. On the histology, &c. Jonm. of Phys., vol. iii. p. 269. 
 Fr. Hofmeister. Das Verhalten des Peptones in der Magenschleimhaut. 
 
 Zeitschr. f. physiolog. Chemie. Bd. vi. p. 69. 
 Schumbnrg. Ueber das Vorkommen des Labferments im mensehlichen Magen. 
 
 Yirohow's Archiv. Bd. vii. C. 
 A. Mayer. Einige Bedingungen der Pepsinwirkung. Quantitativ studirt. 
 Zeitschr. f. Biologie. Bd. xvii. p. 351. 
 
102 LECTURES ON DIGESTION. [Lect. VI. 
 
 Herzen. Observations phys. dans nn cas de fistule gastriqae. Eevue mdd. de 
 
 la Suisse romande, 1884, part i. 
 Heidenhain. Ueber die Absonderung der Fnndusdriisen des Magens. Pfluger's 
 
 Arohiv. Bd. xix. p. 148. 
 Dtlsterboff. Einfluss der Bisenpraparate auf die Magen-Verdauung. Inaugural 
 
 Dissertation. Berlin, 1882. 
 Salvioli. Ueber die Wirkung diastatisoher Permente auf die Blutgerinnung. 
 
 Centralbl. fur die med. Wissensoh. 1885, No. 51. 
 
 Sundberg. Ein Beitrag zur Kenntniss des Pepsins. Zeitsohr. f. physlolog. 
 
 Chemie. Bd. ix. p. 319. 
 Eaudnitz. Prager med. Woohensohr. No. 24, 1887 ; Boas, Zeitsohr. f . klin. Med. 
 
 Bd. xiv. p. 249 ; Johnson, ibid., p. 240 ; Klemperer, ibid., p. 280 ; C. Eosenthal, 
 
 Berlin klin. Woohensohr. 1888, No. 45. Dealing with rennet and rennet 
 
 zymogen. 
 W. Jaworski, Experimenteller Beitrag zur Wirkung der Amara und der Galle. 
 
 Zeitsohr. f . Therapie, 1886, No. 23. 
 J. Boas. Ueber DunndarmTerdauung beim Mensohen und deren Beziehung zur 
 
 Magenverdauung. Zeitsohr. f . klin. Med. Bd. xvii. Hft. 1 and 2. 
 Sohellhaas. Beitrage zur Pathologie des Magena. Deutsoh. Arohiv. f. klin. 
 
 Med. Bd. xxxvi. p. 427. 
 Schiitz. Einfluss des Alkohola und der Salioylsaure auf die Magenverdauung. 
 
 Prager med. Woohensohr. 1885, No. 20. 
 N. Eeiohmann. Ueber den Einfluss bitterer Mittel auf die Function des ge- 
 
 sunden und kranken Magena. Zeitsohr. f. klin. Med. Bd. xiv. p. 177. 
 E. Penzoldt. Ueber die Verdauliohkeit von Pleisohspeisen (nach Versuohen von 
 
 Dr. Gigglberger). Mtinohener med. Woohensohr. 1887, No. 20. 
 
103 
 
 LECTURE YII. 
 
 Gentlemen, — Besides tlie above described fluid matters, the 
 stomacb always contains more or less gas, wbicb consists in part 
 of air swallowed, in part of carbonic acid which proceeds, accord- 
 ing to Lehmann, by diffusion from the blood. Planer found in a dog, 
 five hours after feeding, 25'2 volumes 00^, 68'68 N, and 6'12 
 per cent. But according to Strassburg, the carbonic acid tension 
 of the arterial blood is at highest 4 — 5 vols, per cent., so that the 
 carbonic acid found by Planer could not have proceeded from the 
 blood, but must have been generated in the stomach or intestine. 
 Air is not only carried into the stomach by swallowing, as is 
 certainly proved, but also by coughing or by forced respiration. 
 With the help of a wire oesophagus sound, which served as the 
 electrode of a thermal element, I measured, in the summer of 
 1876, the temperature of the stomach under different conditions. 
 With every inspiration I observed a diminution, which ceased 
 when the subject of the experiment breathed air at the tempera- 
 ture of the body. How far, under normal conditions, the oeso- 
 phagus allows air to pass by means of the variations of expansion 
 undergone by the stomach in consequence of the abdominal 
 pressure, I dare not venture to say, as in cesophagotomy we find 
 the lumen of the oesophagus firmly closed. 
 
 In healthy individuals the temperature of the empty stomach 
 is higher than that of the axilla, the mean of ten observations 
 making it about 0-6° C. But if the person experimented on 
 breathes deeply, even keeping his mouth shut and breathing only 
 by the nose, great variations occur, in which the temperature of 
 the stomach may sink as far as 0'3° 0. below that of the axilla 
 (mean of four observations). Quincke found in a boy of 16, 
 who had a gastric fistula for stenosis of the oesophagus, that the 
 temperature of the stomach measured by a thermometer intro- 
 duced through the fistula was 0'12° 0. higher than that of the 
 rectum. The equalisation of the temperature of variously heated 
 
104 LECTUEES ON DIGESTION. [LbCT. VII. 
 
 fluids— water, milk, &c., of +5° C. and +44°— 49° C. were intro- 
 duced — occurred in these experiments for tlie most part within 
 the first five minutes, and the ener-gy of this equalisation of tem- 
 perature was so striking that half a litre of water at 5° C. was 
 warmed in less than this time to 19° — 20° C. The temperature 
 of milk was raised more slowly. Rodsajewsky had previously 
 performed similar experiments on a gastrotomised patient, and 
 arrived at the following conclusions : After the introduction of 
 food into the stomach the temperature at first falls ; this may 
 be down to the absolute temperature of the food, and is so, if the 
 temperature of the food is moderate or low, but is proportional if 
 this is higher. The equalisation of temperature follows slowly, more 
 slowly in the night than in the day, and most quickly at the 
 time when the person experimented upon is accustomed to take 
 food. 
 
 Kronecker has taken the absolute temperature of the stomach 
 by means of little mercury balls, which could be swallowed. He 
 found it to be in a fasting dog 38*7°, after feeding with bacon it 
 rose to 40'0°, and also after chemical, mechanical, and even 
 psychical stimuli (showing the dog bacon) . The analogy with the 
 relations shown by C. Ludwig of the rise of temperature in the 
 active salivary gland becomes therefore obvious (v. supra, p. 37), 
 because it is a general law that organs in action have a higher 
 temperature than those at rest. The subjective sensations which 
 hot or cold food and drink make in the stomach are well known, 
 they are experienced by every one, and under pathological 
 conditions may be very severe and troublesome. 
 
 The question of the self-digestion of the stomach is of very 
 special interest to us as practitioners with respect to the produc- 
 tion of gastric ulcer. Briicke, as is known, has proved that it 
 involves the mucous membrane at right angles to the glands 
 layer by layer, that the acid reaction is only present in the layer 
 immediately next the lumen of the stomach, and that deeper the 
 reaction is neutral or alkaline. Edinger, on the other hand, main- 
 tains that the mucous membrane of the fundus, as well as that of 
 the pylorus, is acid. If a solution of alizarin-soda is injected into 
 the blood of a living animal, or a so-called self-injection is 
 effected, all the acid tissues become yellow, and all those which are 
 alkaline become red-violet or red. By such experiments it may 
 be shown that the mucous membrane of a digesting dog is acid 
 
SELF-DIGESTION OF THE STOMACH. 105 
 
 throughout its entire thickness, while in a fasting dog the yellow 
 colour is absent. But these experiments appear to me to prove 
 very little, as it is not clear that a diffusion of stomach contents 
 containing hydrochloric acid may not have taken place into the 
 tissues, and in that way brought about the acid reaction. The 
 experiments of Sehrwald, already described (p. 98), contradict 
 them, especially with reference to this source of fallacy in 
 Bdinger's experiments, for they proved that the central cells in 
 the fundus of the gland tubules have an alkaline reaction. 
 
 The famous experiment of Bernard — the leg of a living frog 
 thrust into the opening of a gastric fistula in a dog becomes 
 digested — is easy to repeat, especially with a curarised frog. 
 The cadaveric softening of the stomach, or self-digestion, is 
 indisputable. On the other hand, Leube has very lately shown 
 that pieces of mucous membrane may be torn off in sound- 
 ing or washing out the stomach without any harm resulting. 
 Considerable haemorrhages into the stomach, obviously from 
 large vessels, occur in many acute febrile diseases without any 
 bad result. Gastric ulcers themselves occur without any 
 definable cause, and extend in breadth and depth very slowly 
 under certain conditions, or frequently heal completely. There 
 is one explanation of this : wherever living blood circulates in 
 the mucous membrane under normal pressure, the gastric juice 
 has no point of attack. But where the normal blood nutrition 
 ceases, either in consequence of embola (Virchow) or of ligature 
 of vessels (Pavy), and necrosis of tissue occurs, there, as else- 
 where, the gastric juice digests the dead tissue. Simple haemor- 
 rhages, without distinct fall of blood pressure and slowing of the 
 circulation, are not sufficient, as is evident from many instances 
 of benign hemorrhages. 
 
 The administration of acids, or a simple mechanical lesion, we 
 must maintain, in opposition to Pavy, does not give rise to 
 ulceration. In most cases another factor is present, that is the 
 want of relation between the degree of acidity of the gastric 
 juice and the nutrition of the tissues; it may be that the former 
 is increased immoderately while the cell nutrition remains normal, 
 a so-called hyperacidity resulting, whilst only slight nutritive 
 disturbances exist in the cells; or it may be that the latter, with- 
 out being actually necrosed, have to such an extent lost their 
 normal resisting power, that in spite of the absence of any increase 
 
106 LECTURES ON DIGESTION. [Lect. VII. 
 
 in the formation of acid the necessary disproportion between the 
 two factors is effected. 
 
 Koch and I, starting from a statement of SchiflF's, that certain 
 injuries of the central nervous system are connected with gastric 
 hemorrhages, divided the cervical cord, or the adjacent portion 
 of the dorsal cord, in six dogs, in order to produce haemorrhages in 
 combination with diminished bloodpressure . As a fact we obtained, 
 in those animals which survived longer than 36 hours, numerous 
 lenticular gastric ulcers, which were mostly circular " and as if 
 punched out," going deeply into the submucosa. With the 
 microscope we could see evidence of haemorrhage out of the 
 vessels of the mucous membrane between the glands, and in the 
 entire area of the effused blood the elements of the mucous mem- 
 brane, gland tubules, and connective tissue, were digested deeply 
 down in the shape of a funnel. No traces of inflammatory pro- 
 cesses were to be found. The operative procedure produced a 
 deterioration of the nutrition of the tissues, leading to 
 the formation of typical gastric ulcers, and it needs only a 
 glance at the stomach and the preparations which I show 
 you, to recognise the correctness of my statements. Why 
 these hasmorrhages occur, and why only precisely in the gastric 
 mucous membrane, is quite obscure, but according to a case 
 published by McDowall the same conditions occur in man, as 
 a haemorrhage in the pyloric region led to self-digestion of the 
 stomach, perforation, and erosion of the liver. In opposition to 
 the above-quoted experiment of Bernard's, the carefully shaved 
 paw of a living dog was kept for six hours in a mixture of 
 glycerine gastric extract and hydrochloric acid at the body tem- 
 perature without being at all affected. Our experiments agree 
 with those of Virohow and Pavy, as it was only when malnutrition 
 of the mucous membrane occurred as a consequence of entire or 
 partial interference with the circulation that ulcerative digestion 
 resulted. This is the reason why ulcers remain so long stationary, 
 and increase so slowly in depth and breadth. 
 
 Without going into the other factors for the production of 
 gastric ulcer, as this question will be fully discussed in the second 
 part of this volume, we may here give the experiments of Sehr- 
 wald, because they support a view long held by us. This in- 
 vestigator estimated the diffusion power of the living wall of the 
 stomach as compared with the dead wall, by filling a living 
 
SELF-DIGESTION OF THE STOMACH. 107 
 
 stomach, tied above and below witb a 0-2 per cent, solution 
 of phosphoric anhydride, and noting the changes in this solution 
 which resulted from diffusion ; then after the death of the animal 
 he repeated his experiments with the same apparatus after intro- 
 ducing into the vessels through the abdominal aorta a solution of 
 soda, equivalent to about half the alkali contained in the blood. 
 In the latter case the conditions which exist for diffusion in the 
 living stomach were artificially imitated. By special precautions 
 Sehrwald also avoided the fallacy which might arise from allowing 
 the glands in the stomach to secrete. The outcome of these 
 experiments was that the balance between the alkali of the blood 
 and the acid of the stomach contents in the living animal was 
 found not to be in accordance with the laws of diffusion, but 
 much less than it was in the dead gastric mucous membrane, 
 although the conditions in the latter case were much more 
 unfavourable than in the former. The living epithelium must 
 also diminish the amount of alkali given to the blood from 
 the stomach contents, and thereby it does the organism double 
 service, as an economiser of alkali and a protection to the 
 blood, and secondly, as an economiser of hydrochloric acid and 
 protection to the stomach, so that the body is able to economise 
 in a notable degree both in the work of secretion and of absorp- 
 tion. But it is thereby proved that the protection of the stomach 
 is only effectual so long as its cells are living and active. As a 
 lesion of the cell life may occur, either by disturbances of the 
 circulation or by direct lesions of the epithelium, or through 
 disturbances of the trophic nerve influence, we get in Sehr- 
 wald's experiments a very valuable experimental basis for one of 
 the above described causes of gastric ulcer, namely, lesions of the 
 epithelium. Still, in spite of all, it remains obscure why 
 these lesions of the epithelium and the formation of ulcers occur 
 only in circumscribed spots, and why their predilection is for 
 particular parts of the mucous membrane. The fact that the 
 gastric juice does not digest living tissue, nor therefore the gastric 
 mucous membrane, we must attribute to the special properties 
 of living cells. Yet it does not remain less wonderful, because 
 the same fact recurs in other places in organic life. Why does 
 not the pancreas digest itself? Why can living moUuscs, e.g., 
 Boliim, galea, produce with impunity a secretion containing free 
 sulphuric acid, while the excised gland is at once destroyed by 
 
108 LECTURES ON DIGESTION. [Lbct. VII. 
 
 it ? Here again we have tke living cell possessing an immunity 
 against its sebretion, just as the torpedo does not feel the 
 shock of its own electrical organ. 
 
 In those disorders of the stomach which occasion either an 
 insufficient secretion of acid, or an abnormal delay of the food in 
 the stomach, fermentative decomposition in the ingesta arises very 
 easily. The carbohydrates are decomposed ultimately into gas- 
 forming products, and according to the kind of fermentation 
 exciters present — as we have seen in the introduction, they are 
 always brought in from without — sometimes alcoholic or acetic 
 fermentation, sometimes lactic or butyric fermentation develops. 
 The micro-organisms present in the stomach in pathological con- 
 ditions have been recently investigated very carefully by de Bary 
 and von Miller, but they have come to only slight conclusions 
 relative to their pathogenetic action. De Bary has found quite a 
 number of yeast fungi and schizomycetes, and even the so-called 
 sarcina ventriculi, oidium lactis, bacteria, mucor and flagellate 
 forms, without being able to define precisely their chemical or 
 pathological action, except in a negative direction — that is, that 
 we must not infer the nature of a fermentation from the presence 
 and growth of a yeast fungus, as we are accustomed to do from 
 the analogy of the action of common yeast, whilst the schizo- 
 mycetes, for example, oidium lactis, certain forms of bacteria, and 
 sarcinse, undoubtedly give rise to a typical fermentative action. 
 Miller succeeded in cultivating a large series of yeast fungi from 
 the stomach contents of the stomach of a man who was able to 
 empty his stomach at will after ingesting a small quantity of 
 fruit, and who was at the same time not in a normal state of 
 health. These organisms gave rise to intense fermentation, in 
 part with copious development of gas. He succeeded, by feeding 
 a healthy dog with the organisms, in inducing serious digestive 
 disturbances, varying with the composition of the food taken at the 
 same time ; in other words, the nutritive media of the organisms 
 influenced in a marked degree the nature of the fermentation, 
 and when he himself finally swallowed a quantity of a test tube 
 cultivation of bacterium serogenes, he suffered from distension of 
 the stomach with gas and indigestion, which lasted many days. 
 
 The first careful exposition of these relations we owe to 
 Frerichs, whose ingenuity transferred the employment of fermen- 
 tation equations to pathology. In the following table you have 
 
GASTRIC FERMENTATION. 109 
 
 before you the steps of the fermentations in question, and you 
 ■will at the same time bear in mind the organisms which give rise 
 to them. 
 
 Cj H,2 Oe Sugar 
 
 2 (Cj Hj 0) Alcohol + 2 COj 2 (C, H^ O^) Lactic acid 
 
 Cj Hj + = Cj H, (Aldehyde) + Hj C, H, Oj + 2 COj + H. 
 
 C2 H4 + = Cj Hi Oj (Acetic acid) (Butyric acid) 
 
 Schultzen and Wilson have shown that many forms of fermen- 
 tation may occur together. I had the opportunity, in company 
 with my lamented colleague Eupstein, of observing a case in 
 which, as the patient very pithily observed, " there was some- 
 times a vinegar factory and sometimes a gas-works in his inside." 
 In the one case the alcoholic fermentation led to the formation of 
 acetic acid, in the other the butyric fermentation produced hydro- 
 gen and carbonic acid. This patient was specially remarkable, 
 as he at times belched higher hydrocarbons, such as marsh gas, 
 and (perhaps) defiant gas, which took fire when a light was held 
 in front of him, and burnt with a faintly luminous flame. In 
 this case there must have been present still another fermentation, 
 that of marsh gas. Hoppe-Seyler thinks marsh gas might be 
 regurgitated out of the intestine. Since we know from this 
 observer that an active development of marsh gas takes place 
 from cellulose in sewer mud, it appears to me that the formation 
 of this gas in the stomach is quite possible. A connection between 
 the diflferent fermentations and the kind of food was not proved. 
 The man died later on, and we found that he had not, as we 
 imagined, a dilated stomach, but a flat scirrhous tumour of the 
 pylorus. The shape of the tumour accounted for our failure to 
 detect it by palpation, but it caused decided stricture of the 
 orifice. 
 
 But it is not only the carbohydrates which undergo the destruc- 
 tive decompositions in the stomach which we have just sketched. 
 The albuminous bodies also undergo under certain conditions 
 extensive decompositions, which, as we have described in the 
 second lecture, by the action of bacteria lead to the formation of 
 amidic acids, fatty acids, phenol, indol, and other bodies of the 
 aromatic series, in which as products of the tissue metamorphosis 
 of bacteria certain very highly poisonous bodies, ptomaines 
 and toxins, are formed. Bat this happens only when the reaction 
 
110 LECTURES ON DIGESTION. [Lbct. TH. 
 
 is alkaline, without which the decomposition, which is identical 
 with putrefaction, cannot occur. But in the stomach not only 
 is there normally an acid secretion, so soon as ingesta are 
 brought into it, but the hydrochloric acid has such strong anti- 
 septic properties, and prevents so completely the growth of 
 micro-organisms (Sieber, Miquel, Kast), that some recent authors, 
 e.g., B. Bunge, have regarded its most important property as not 
 its action on peptic digestion but its eifect as a bactericide. If 
 this view unquestionably goes beyond the mark, for as already 
 stated I have known a number of persons, some of them for some 
 years, who had no hydrochloric acid in their stomach contents 
 without any putrefactive phenomena being noticeable, it is still 
 unquestionably true that putrefaction occurs only when the for- 
 mation of free acid in the stomach ceases, and the abnormal 
 delay of the ingesta gives an opportunity for further decomposi- 
 tions to take place. Minkowski has recently explained these 
 relations in a brilliant contribution to the subject of stomach 
 putrefactions, but he has also shown that the stomach is not to be 
 regarded as a completely trustworthy sterilising apparatus, as it 
 can only control within certain limits and guide in definite direc- 
 tions those processes of decomposition which are caused by the 
 micro-organisms which gain entrance with the food, and which 
 develop in part in the stomach, but more especially in the intestine. 
 Moreover, it appears that for this purpose not the hydrochloric 
 acid only but also pepsin plays a part, as the organised bodies 
 become digested by the combined action of both factors. In 
 gastric juice containing hydrochloric acid, in which the pepsin 
 has been destroyed by boiling, an abundant growth of toruls 
 and bacilli occurs after contamination. Spallanzani long ago 
 observed that pieces of meat put into gastric juice for days did 
 not putrefy. Gastric juice containing hydrochloric acid or 
 gastric contents may be left exposed to the air for a week with- 
 out decomposition or formation of micro-organisms, whilst if it is 
 feebly acid, neutral, or alkaline, it soon becomes cloudy from 
 micro-organisms and has a putrid smell. We must therefore 
 believe that in disease by absorption of toxins an autointoxica- 
 tion of the patient occurs, and in fact a part of the symptoms of 
 dilatation of the stomach and cessation of the secretion of hydro- 
 chloric acid must be attributed to such a process. Certain 
 French authors, Bouchard, Dujardin-Beaumetz, and others, 
 
THE GASTRIC JUICE IN FEVER. Ill 
 
 have expressed this view, and have tried " disinfection " of the 
 stomach and intestine. 
 
 "When we come to consider the influence of general pathological 
 changes on the secretion of the gastric juice, fever must be placed 
 in the first rank, in accordance with the observations of Beaumont 
 and the experiments of Manassein. In fever, from whatever 
 cause, the gastric secretion does not indeed cease, but obviously 
 a less active juice is secreted. My own experience enables me 
 to confirm this in the most complete manner with respect to the 
 human subject. If we wash out with an equal quantity of water 
 the fasting stomachs of two individuals, one healthy and the other 
 sufiering from fever, after having given to each of them, for the 
 purpose of stimulating temporary secretion, a little tinct. capsici, 
 and submit an equal quantity of albumen to the action of an 
 equal quantity of filtered stomach extract from each of the cases, 
 we find that the gastric juice from the fever case digests much 
 less, or at least much more slowly, than that from the healthy 
 person. The reaction is usually acid, rarely neutral : I have 
 only once or twice met with an alkaline reaction. Still we can, 
 as Hoppe-Seyler points out, strengthen digestion by adding 
 hydrochloric acid. This confirms the old practice of prescribing 
 phosphoric or hydrochloric acids in fever mixtures. The diminution 
 of the pepsin digestion is not in all cases equally great, or indeed 
 present at all. In fever patients without distinct dyspepsia 
 Sassezki found no diminution of the digestive activity of the 
 gastric juice. Gluczinski, in a long series of experiments, observed 
 that, generally speaking, in acutely febrile patients the secretion 
 of hydrochloric acid ceased, and the formation of pepsin diminished, 
 but that in chronic fever patients hydrochloric acid may be found. 
 But the secretion of pepsin and hydrochloric acid go hand in 
 hand, so that in the first case there was not a complete cessation, 
 only a diminution of the secretion, to such a degree that free 
 acid was no longer demonstrable. Ufielmann observed in a gas- 
 trotomised lad who had chronic fever rising to 39-2° (102-5° P.), 
 that, as above remarked (p. 93), albumen solutions were converted 
 into peptones after twenty minutes, and the boy increased 18 — 19 
 per cent, in weight in the course of twelve weeks' fever. In an epi- 
 demic of diarrhcBa, the same observer examined the vomit of the 
 patients, and found at first, in spite of the fever, that it was 
 actually more acid than normal ; but later on the reaction 
 
112 LECTURES ON DIGESTION. riECT. VH. 
 
 changed suddenly to alkaline simultaneously with the discharge 
 of slimy bilious masses, and — always an unfavourable sign — the 
 digestive powers thenceforth completely disappeared. On the 
 other hand, the gastric contents sometimes have an alkaline 
 reaction, of course apart from the effects of medicine. This 
 occurs when a strongly alkaline transudation is poured out into 
 the stomach in connection with diminished or entirely abolished 
 secretion of acid. 
 
 To these changing or even capricious conditions of production of 
 hydrochloric acid belong the dyspepsias of nervous origin which we 
 see occur as a consequence of great emotional disturbance, or as 
 a chronic disorder, genuine nervous dyspepsia, caused by general 
 nervous conditions. Also reflex dyspepsias may be classed here. 
 Ruff relates, for example, the case of a patient who suffered for 
 some days from complete abolition of the functions of the stomach, 
 but whose appetite and digestive activity suddenly returned after 
 the removal of a plug of wax from his ear. 
 
 It is impossible on this occasion to enter into the manifold 
 pathological conditions which give rise to alterations in the chem- 
 istry of digestion in the stomach. These relations have recently 
 been studied on all sides, by the help of new methods for the in- 
 vestigation of the functions of the stomach, and are fully discussed 
 in the second part of this volume. Here we may only remark 
 that many diseases may lead under certain conditions to interfer- 
 ence with the gastric digestion, with its chemistry, and with the 
 motor functions and absorption of the organ in question. Local 
 changes of its mucous membrane and muscular wall, alterations 
 «f its circulation and innervation, direct and indirect, go 
 hand in hand, and result in a variable but more or less definite 
 pathological condition. The insufficient action of one or other of 
 the above-named factors may temporarily be compensated by a 
 greater activity on the part of the other, as, for example, when an 
 insufficient peptic digestion is aided by the rapid transference of 
 the stomach contents to the intestine where the work of digestion 
 is completed. 
 
 A very important fact, not only interesting from a physio- 
 logical point of view, but of the greatest pathological significance, 
 was first demonstrated by the experiments of Ludwig and 
 Ogata on dogs, and afterwards confirmed by Czerny, who kept a 
 dog alive for as long as six years after extirpation of his 
 
DIGESTION WITHOUT THE STOMACH. 113 
 
 stomacb. The post-mortem examination of this animal showed 
 that there still remained a small piece of the stomach wall 
 enclosing a rounded cavity filled with food, but Ludwig and 
 Ogata in their experiments got complete control of the stomach 
 without extirpating it, by so completely shutting off the pylorus 
 by introducing a uterine dilator into it that no gastric juice 
 could possibly enter the intestine. Food was injected in large 
 quantities directly into the duodenum, and sufficed to main- 
 tain the body-weight of the animal. Very remarkable were 
 the changes in the food under these conditions, for while raw 
 minced meat digested well, cooked meat, on the other hand, 
 after a few hours was passed scarcely or not at all changed. 
 Jaworski was the first to draw attention to these conditions from 
 the clinical side, his statements being soon supported by other 
 investigators (Ewald, Rosenheim, &c.). 
 
 You will find further information, gentlemen, in the second 
 part of this volume, but here we shall only state that a scientific 
 basis for treatment is to be obtained only by an exact diagnosis 
 of diseases of the stomach, which may be made by a careful 
 chemical investigation of the gastric juice or the stomach con- 
 tents, the qualitative estimation of its acidity, the testing of 
 the starch digestion, and the action on albuminates, that is, of 
 its peptonising power. 
 
 If we desire to examine the chyme, the product of digestion, 
 we may study it in gastric fistulas, or by the aid of the stomach- 
 pump, or by the method of expression recommended by Boas 
 and myself. Allow me here to describe only some typical 
 constituents. With respect to the greater or less solubility or 
 digestibility of particular articles of diet, I must refer you to the 
 tables at the end of Lecture VI. 
 
 Muscular tissues are dissolved more or less rapidly, according 
 to the resistance of their perimysium, their fasciee, and their 
 accompaniments of fat and tendon, until the gastric juice has 
 only the fibrillae themselves to deal with. Fat meat is much 
 harder to digest than lean, old than young, raw than cooked. 
 These differences depend upon the solution of the fibrous stroma 
 by cooking and its digestion in the acid gastric juice. The 
 proper pepsin digestion is probably equally rapid for all 
 muscular fibres. ; They are decomposed into their primitive 
 bundles, and these into a granular mass, in which their finer 
 
114 LECTURES ON DIGESTION. [Lect. VII. 
 
 structure cannot be recognised. Prerichs says that muscular 
 fibre is never completely dissolved in the stomacb ; and in fact 
 we find numerous unchanged fibrillee in the smaill intestine, as I 
 have recently described in a case of praeternatural anus. 
 
 Gelatine and gelatine-yielding tissue (cartilage and bone) are 
 very hard to dissolve. If the gelatine is extracted from the 
 bone, it is changed, according to Uffelmann, into a substance 
 very like peptone and sugar. This result of Ufielmann's inves- 
 tigations is all the more welcome, as a long controversy has been 
 waged concerning the fate of gelatine in digestion. Gelatine is 
 very like peptone in its reactions. It does not coagulate on 
 heating, is not precipitated by acids, turns polarised light to the 
 left, but it gelatinises in the cold, and diffuses scarcely at all 
 through animal membranes. Frerichs, Kiihne, and Etzinger 
 maintain that the gastric juice abolishes the capacity of gelatine 
 to gelatinise, and according to Hoppe-Seyler it is almost entirely 
 soluble in acids. Uffelmann observed that gelatine, swollen in 
 water, after a long stay in the stomach no longer formed jelly, 
 but diffused easily. It thus approximates very closely to true 
 peptone, with which it agrees also in some of its reactions with 
 precipitating agents. In fact, gelatinous substances are well 
 borne. I can, from my own experience, confirm the good 
 results of the gelatine mixture proposed by Senator as a fever 
 diet. 
 
 Milk becomes coagulated, and its fat in part included in the 
 coagula ; the casein then peptonises. The latter does not occur 
 if the coagula are removed too quickly, as we see in the well- 
 known white lumps in the diarrhoeic or dyspeptic stools of 
 children, which are formed of nothing but fat and casein. 
 
 Vegetables, so far as their envelopes of cellulose permit, are 
 easily dissolved and digested. Gums, according to earlier views 
 (Frerichs, Gorop-Besanez) were not digestible. Voit and Uffel- 
 mann, however, state that gums and cane sugar are converted 
 into grape sugar, and Leube has shown that human gastric juice 
 converts cane sugar into grape sugar, but the grape sugar is so 
 rapidly removed from the healthy stomach, being probably 
 absorbed, that after a relatively short time no trace of it can be 
 found, whilst under certain pathological conditions this capacity 
 of absorption is absent. The latter appears to be the case in 
 dilatation of the stomach. 
 
THE CHYME. 115 
 
 The reaction of tte chyme must naturally depend chiefly upon 
 the nature of the ingesta, but also is conditioned by the secretion 
 of gastric juice, and varies according to the length of time the 
 food remains in the stomach. If anyone eats a large quantity 
 of organic acids, e.g., vinegar or acid salts, with a meal, the 
 contents of the stomach must have an acid reaction from the 
 first depending upon the substances thus swallowed. 
 
 However, this is only an exception, and the acidity depending 
 upon the accidental characters of the food is a matter of subor- 
 dinate interest. 
 
 We are concerned with the curve of the hydrochloric acid 
 secretion of the gastric glands, and the acidity of the chyme 
 which varies with the duration of digestion. The course of such 
 a curve may be very readily constructed. Given a neutral diet, 
 the gastric contents will give an acid reaction only when suffi- 
 cient acid has been secreted to satisfy the affinities of the albu- 
 minates and basic salts in the food, and according to their 
 chemical relations these become converted into acid compounds, 
 or the feebler acids are set free. Then after further secretion free 
 hydrochloric acid appears, the quantity of which " depends upon 
 the strength of the stimulus which the food exerts on the 
 stomach," as Tiedemann and Gmelin, as early as 1825, concluded 
 from their experiments. 
 
 Heidenhain found the acid contents of the pure fundus secre- 
 tion during the first eight hours of digestion to vary very slightly, 
 that is, only between 0'48 and 0'55 per cent. HCl. 
 
 Cahn proved in dogs, by careful estimations, that the healthy 
 animal stomach answers to equal stimuli by equal and regular 
 secretion; Eothschild, Hirsoh, Penzoldt, and v. Jacksch have 
 studied the acidity curve in the human stomach, and one and all 
 have found that where the food is the same, the course of the 
 curve is identical, so that with a moderate supply of food 
 (Hirsch gave 500 grms. boiled milk, 2 soft eggs, and a white 
 roll ; Eothschild gave 200 grms. of pure meat) the maximum 
 was reached about the end of the second hour or the beginning 
 of the third hour, that it lay between 2-3 and 2-8 to 3 per mille 
 HGl, and in the further course of digestion diminished. 
 During the course of this curve, the rapidity with which the 
 maximum is reached varies with difierent persons, and may 
 vary even with the same individual on difierent days; the 
 
116 LECTURES ON DIGESTION. [Lect. VII. 
 
 final degree of acidity, with ordinary diet, appears to lie within 
 the above-named limits, and consequently is, in a manner, 
 regulated by means of secretion, absorption, and expulsion, 
 so that the acidity of the chyme from free acid cannot overstep 
 ever so little this definite limit, just as the alcohol contents of a 
 fermenting fluid cannot surpass a certain maximum figure. Still, 
 this maximum is not absolute, but depends upon the reaction 
 and amount of the diet, as Hirsch found after an unusually heavy 
 midday meal the figure was above 3-0 to 4 per mille in his own 
 case. These figures are, therefore, relative, not absolute. 
 
 Finally, gentlemen, we have the question, whether in gastric 
 digestion the albuminous bodies are converted into peptone in 
 the above defined sense, or whether they remain in a preliminary 
 stage, as Kuhne's protalbumose or Schmidt-Mulheim's propeptone ? 
 That true peptone is formed from albumen by long-continued 
 digestion is, according to the experiments of Kiihne and others, 
 not to be doubted, but whether the relatively short time 
 which the albuminous substances remain under normal conditions 
 in the stomach is sufficient for this purpose is not certain. The 
 ordinary biuret-reaction in the presence of peptone is not suffi- 
 cient to decide this, as our previous remarks have shown, because 
 propeptone, too, gives the characteristic purple colour with 
 copper solution in the cold. The discovery by Kiihne, that all 
 previous stages of peptone are precipitated from digestive fluids 
 by ammonium sulphate, makes it possible to settle this question. 
 I have recently performed some experiments with the stomach 
 contents of healthy and diseased persons, both after small and 
 heavy meals, test breakfasts, and ordinary midday meals, in 
 which the contents of the stomach were obtained by means of 
 a tube after one, two, three, and more hours of digestion, so long 
 as any chyme remained. The filtrate was either, after previous 
 removal of the albumen, saturated with powdered ammonium 
 sulphate, or precipitated with saturated ammonium sulphate 
 solution, filtered to remove the salt, evaporated to a small volume, 
 treated with great excess of caustic potash, whereby the am- 
 monia is given off and a precipitate of sulphate of potash occurs. 
 The filtered solution now contains all the peptone which was in 
 the stomach contents,, and may b6 ' demonstrated by the biuret 
 reaction.. Almost ivithout exception this reaction was very feeile; 
 being absfent altogether in some pathological cases, although in 
 
THE PfiODUCTION OF GASTSIC ULCER. 117 
 
 all cases ttefresWyL expressed gastric ■ contents gave a strong 
 biuret reaction; this difference was tlie more marked as tlie latter 
 could liave contained only a fraction of tke peptone present, 
 while, in the experiment just described, the whole of the peptone 
 must have been collected together. Unfortunately we do 
 not possess any method by which such investigations can be 
 made quantitatively ; we are obliged to rely upon an optical 
 examination, which, however, in. this, case seems so definite that 
 the assertion appears to be justified, that the greater part of the 
 albuminous bodies in the stomach does not generally become 
 converted into peptone. 
 
 On the question of the origin of gastric uher, Koch and I made 
 six expejfiments on artificial lowering of blood-pressure by section 
 of the. cord, and two in which the lowering of blood-pressure 
 was efiected by copious venesection without section of the cord. 
 The former animals had their cords divided at the height of the 
 fourth cervical or second dorsal vertebra, and the animals after 
 the operation were covered up warmly or put into a warm 
 chamber with an inside temperature of 30° 0. In the first 
 experiment, we tied at the same time the duodenum at the 
 pylorus and some of the branches of art. gastro-epiploica dextra 
 going to the stomach. The animals were fed in the morning of 
 the experiment with bread and meat, and then, with the 
 exception of Experiment lY., no more food was allowed, but 
 every day 60 to 100 ccm. of hydrochloric acid solution were 
 administered by the oesophagus-tube. All the animals were 
 dead in the course of sixty hours, that is, they either died 
 as a result of the operation, or were killed,, as in the case of 
 the dog rendered anaemic by venesection, and that in Experi- 
 ment I., which was killed. Only one dog with section of the 
 spinal cord lived ten days (Experiment IV.). The ansemic dog 
 had scarcely any changes .in his stomach. All the animals with 
 divided cords had typical gastric, and some duodenal ulcers, when 
 they had lived longer than thirty-six hours after the operation. 
 But these were only three out of the six dogs. In these cases the 
 changes were quite characteristic, as shown in the following 
 note from Experiment IV. : — 
 
 A middle-sized poodle. On the 17th July, 1878, section of 
 the cervical cord at the level of the seventh vertebra. After the 
 operation, complete paralysis of the lower extremities. The 
 
118 LECTURES ON DIGESTION. [Lect. VII. 
 
 animal is so lively that it crawls about the room by its fore-legs, 
 barks, &c. ; 50 com. of hydrochloric acid solution, 2 p.c, daily ; 
 eats well. This state continued till July 25th. The dog then 
 became sickly, ate no more, and died on the 28th July. The 
 temperature was normal to the 27th. Autopsy: stomach con- 
 tents: a little thick, brownish red mucus; shows only reddish 
 brown detritus, sometimes aggregated in heaps, sometimes in 
 lumps and punctiform. No muscular fibres, crystals, starch, 
 sarcinae, vibrios, or other fungi. The stomach contents mixed 
 with a little water and filtered did not digest fibrin'' Mucous 
 membrane: pale, anaemic. From the cardia, especially in the 
 fundus, covered with numerous superficial losses of substance, 
 the size of a pin's-head to a millet-seed, generally round, though 
 sometimes oval or irregularly notched. These were bounded by 
 a thin border of whitish, apparently intact, mucous membrane, 
 sharply contrasting with its surroundings, so that the whole 
 had some resemblance to herpes circinatus. In the proper 
 ulcers the outer ring was more difiuse. The former were often 
 covered with brownish red, easily removable mucus. Only in a 
 few places did the ulceration reach the muscular coat. These 
 ulcers were always at the apices of the folds or on their sides, 
 never at the bottom. About 3 ccm. above the pylorus they 
 were increased in size, especially upon a transversely running 
 fold, where they were deeper, and covered with a dark, blackish 
 brown adherent scab. The largest ulcer, close to the pylorus, 
 was 1-7 cm. long. The duodenum was much injected, the 
 mucous membrane everywhere relaxed. Just below the pylorus 
 were two shallow ulcers the size of peas, similar to those in the 
 stomach. The serous coat of the stomach and intestine was 
 normal. Otherwise nothing particular. Section of cord com- 
 plete. Microscopically, thin sections at right angles to the surface 
 of the stomach, hardened in bichromate of potash and alcohol, 
 showed that the gland tubules in the bloodless ulcers towards 
 the submucosa were eroded away (digested?), without there 
 being any pus corpuscles, fresh connective tissue corpuscles, 
 or other evidence of an inflammatory process. The dark brown 
 scabs already referred to were formed by the blood on the 
 hsemorrhagic ulcers, which was poured out on the floor of cup- 
 shaped ulcers, and lay between the gland tubules and in the 
 submucous tissue. Their origin from a (eroded?) vessel of 
 
THE PRODUCTION OF GASTRIC ULCER. 119 
 
 the submucosa was very visible in some places. In tbe deepest 
 places the tubules were quite destroyed; between masses of 
 detritus, blood corpuscles, and remains of intertubular tissue, 
 lay some well-preserved gland cells. In other places the vessels 
 must either have been opened as the ulcer penetrated the mucosa, 
 or the haemorrhage must have originated in the intertubular 
 vessels, which we saw in such places still covering a remnant 
 of the fundus of the tubules in the submucosa in the entire 
 extent of the ulcer, whilst the bleeding vessel appeared to lie 
 ■under them in the submucosa. We noted quite analogous 
 appearances in the other two above-named cases. In a quite 
 healthy dog, which for four weeks had daily 50 ccm. of hydro- 
 chloric acid solution of 2 p.c, without any result appearing, on 
 the 18th to the 20th August on each occasion about a quarter 
 of the entire blood was drawn from a vein. The dog collapsed 
 and died on August 21st. On dissection, we found the gastric 
 mucous membrane as if tanned; the stomach small, pale, and 
 contracted. On a white, bare-looking, connective tissue-like 
 ground were numerous pale red prominences which resembled 
 urticaria. They were, as shown by microscopical examination, 
 the remains of the proper gland substance. Here a more diffuse 
 superficial erosion was caused by the hydrochloric acid, but 
 no proper ulceration resulted, and obviously it was the chronic 
 excess of acid fluid, so far beyond the physiological proportion, 
 that brought about this change. 
 
 Planer. Die Gaae dea Yerdannngsachlauchea nnd ihre Beziehtmgen zum Blute. 
 
 Wiener Sitzgaber. Mathem. naturwiaa. Claaae. Bd. xlii. 1860. 
 Strassburg. Zur Topographie der Gasspannungen. PflUger's Arohiy. Bd. vi. 
 Sohultzen. Mittheilnngen aus dem ohem. Laboratorium, &o. Eeiohert u. du 
 
 Bois' Arobiv. 1864, p. 591. 
 Wilaon, quoted by Bndd. On the Organic Diseases and Functional Disorders 
 
 of the Stomach, p. 230. 
 Ewald. TJeber MagengShrung und Bildung von Magengasen mit gelb brennender 
 
 Plamme. Eeiohert u. du Bois' Archiv. 1874, p. 217. 
 PopofE. Ueber die SumpfgasgShrung (aua dem Laboratorium von Hoppe-Seyler). 
 
 PflUger's Arohiv. Bd. x. p. 113. 
 Iieube. Bemerkungen fiber die Ablfisung der Magenaohleimhaut durch die 
 
 Magensonde und ihre Polgen. Deutsoh. Arohiv. f. klin. Medioin. Bd. yiii. 
 
 p. 496. 
 Schiff. Lemons anr la physiologie de la digestion. Florence et Turin, 1867, 
 
 p. 416. 
 
120 LECTURES ON DIGESTION. ;[Lect. VII. 
 
 ManassKin. ChemiBche Beitrage zur Fieberlehre. Virohow's AroWv. Bd. Iv. 
 
 p. 413. 
 Gosse, quoted by SpallainZani. Experiences enr la digestion, par Jean Cenebieir. 
 
 Genfeve, 1783. 
 Ewald. Ueber das Verhalten des Pistelsecrets, &c., bei einem an Anus prffiter- 
 
 natnralis leidenden Kranken. Virohow's Arohiv. Bd. Ixxv. p. 409. 
 
 XTffelmann. Beobaohtiingen und Untersuehungen an einem gastrotomirten 
 
 fiebemdeu Kranken. Deutscli. AroluT. f . klin. Med. Bd. xx. p. 535. 
 Senator. Untersuehumgen iiber den fieberhaften Process und seine Behandlnng. 
 
 Berlin, 1873. 
 Uffelmann. Die Storungen der Verdauungsprooesse in der Enhr. Deutsoh. 
 
 Archiv. f. klin. Med. Bd. xiv. p. 225. 
 Kroneokerand Mayer. DerGebrauchvon verschluckbaren Maximalthermometern. 
 
 Verhandl. d. physiol. Gesellsch. zu Berlin, 1879, p. 121. 
 
 De Bary. Beitrag zur Kenntniss der niederen Organismen im Mageninhalte. 
 Aroh. f. exp. Pathol. Bd. xx. p. 243. 
 
 L. Edinger. XTeber die Eeaction der lebenden Magenschleimhaut, Pfliiger's 
 Arch. Bd. xix. p. 247. 
 
 W. McDowall. Case of haemorrhage into the walls of the stomach, followed by 
 self -digestion of the organ. Lancet, July 11th, 1879. 
 
 Sassezki. Ueber den Magensaft Fiebemders. Petersb. med. "Woohensohr. 1879, 
 No. 19. 
 
 H.Tappeiner. Ueber Celluloaeverdauung. Berichte d. deutsche chem. Gesellsch. 
 Bd. XV. p. 999. 
 
 Vergleiohende Untersuehungen der Darmgase. Zeitschr. f. physiol. 
 
 Chemie. Bd. vi. p. 803. 
 
 Enff. Eeflex-Dysphagie. Monatsschr. f. Ohrenheilkunde. 1878, No. 12. , 
 
 W. Leube. Ueber die Verandernngen des Eohrzuokers im Magen des Mensohen. 
 Virohow's Archiy. Bd. Ixxxviii. p. 222. 
 
 Eodsajewsky. Einfluss der Nahrungsaufnahme auf die tSglichen Temperatur- 
 schwankungen des Korpers im Allgemeinen und des Magens im Speoiellen 
 beim normalen Menschen. Petersb. med. Wochensohr. 1885, No. 28 and 29. 
 
 Quincke. Ueber Temperatur und Warme-ausgleich im Magen. Arch. f. exp. 
 Pathol. Bd. XXV. p. 375, 1889. 
 
 Sehrwald. Was verhindert die Selbstverdauung des lebenden Magens? Miin- 
 ohener med. Woohenschr. 1888, No. 44 and 45. 
 
 Bbstein. Experimentelle Untersuehungen iiber Blutextravasate im Magen. 
 Arch. f. exp. Pathol. 1874, p. 83. 
 
 Gluozinski. Ueber das Verhalten des Magensaftes im fieberhaften Krankheiten. 
 Deutsches Aroh. f. klin. HeS. Bd. xlii. p. 481. 
 
 Bunge. Lehrbuoh der physiol. und pathol. Chemie. 1887, p. 140 and p. 177. 
 (Peptones). 
 
 Kast. Ueber die quantitative Bemessnng der antiseptisoheu Leistung des 
 Magensaftes. Festschrift zur Eroffnung des Hamburg-Eppinger Kranken- 
 hauses, 1889. 
 
 Miquel. Die antiseptische Wirkungskraft versohiedener chemisoher Stoffe 
 gegen Bacterien. Centralbl. f. allg. Gesundheitspfl. Bd. ii. p. 403, 1884. 
 
BIBLIOGRAPHY. 121 
 
 O. Minkowski. Ueber die gahrnngen im Magen. Mittheilung^. aua det med. 
 
 Klinik zu KOnigaberg in Pr. 1888. 
 Miller. Einige gasbildende Pilze des Verdautmgstractus, &o. Deutsche med. 
 
 Wochenaohr. 1886, No. 6, and Ueber GahrungsTorgange im Terdauungstractns 
 
 nnd die dabei betheiligten Spaltpilze. Ibid., 1885, No. 49. 
 A. Cahn. Die Verdanung des Meisohes im normalen Magen. Zeitschr. f. klin. 
 
 Medicin. Bd. xii. H. 1 and 2. 
 Bothschild. Ueber das Verhalten der Salzsilnre des Magens in den versohiedenen 
 
 Zeiten der Verdaunng, &c. Inaug.-Diss. Strassbnrg, 1886. 
 Hirseh. Beitrag zur Bestimmung der Saure des Magensaftes beim Gresnuden. 
 
 Inang.-Diss. Wurzburg, 1887. 
 
122 
 
 LBCTUEE YIII. 
 
 Gentlemen, — The stay of the chyme in the stomach camiot be 
 stated in precise figures, because the observations respecting it 
 differ widely. Moreover, those on men were made in cases of 
 fistula, in which some pathological influence may have been 
 present. We only know that the stimuli which different in- 
 gesta create on the movements of the stomach and the closure of 
 the pylorus, vary according to mechanical and chemical condi- 
 tions, so that the pressure under which the chyle exists in the 
 stomach is not only, as above remarked, dependent on the 
 muscles of respiration, but directly and in a variable manner 
 upon the contraction of the wall of the stomach. Ufielmann 
 introduced, in such a manner as to be air-tight, a sort of pressure- 
 tube through the fistula into the full stomach of his boy, and 
 saw that the level of the fluid in the tube stood in a varying 
 manner at 2 — 8^ cm. over the fistulous opening, and showed, in 
 addition to respiratory variations of only a millimetre or so, 
 great risings and fallings which occupied about one minute. 
 These secondary movements are obviously to be regarded as the 
 expressions of the peristaltic contractions of the stomach. But 
 tesides this, the fluid ia the tube diminished, that is, its level 
 sank gradually lower and lower as the opening of the pylorus 
 (and the absorption of the fluid contents) caused the contents of 
 the stomach to grow less. Schreiber often found in parts nega- 
 tive, in parts a minimum positive pressure, which, however, never 
 exceeded 15 mm. In the case observed by v. Pfungen (a 
 boy with a gastric fistula) the pressure was much higher, this 
 being constantly from 4 to 15 mm. mercury (o"2 to 19'5 cm. 
 water), when the fistula was closed, and varying from the effects 
 of peristalsis between 14 and 35 mm. mercury. The amount 
 was still higher in the antrum pylori, reaching to between 60 
 and 120 mm., so that the motor power of the body of the stomach 
 was to that of the pyloric portion, on an average as 24 : 77, or under 
 certain conditions as 35 : 120 (vide supra, p. 78). By stretching 
 
THE PYLORIC DISCHAEGE. 123 
 
 and disorganisation of the wall of the stomach, either by immo- 
 derate use of food, or by gases, the motor power of the muscular 
 wall is diminished, and the transfer of the chyme into the intes- 
 tine is delayed. In general, the food remains from one to six 
 hours in healthy stomachs, but under pathological conditions 
 much longer. In healthy dogs we often find the pieces of meat 
 given them on the previous evening still in their stomachs at 
 the following noon, whilst rabbits' stomachs generally do not 
 become empty even after very long fasting. On washing out 
 the stomach, we often find undigested remains which must have 
 lain all day in the stomach. I cannot recall who relates the case 
 in which, during the washing out of the stomach in the spring, 
 grape seeds were found which the patient evidently had not 
 swallowed later than the previous autumn. A similar case has 
 been recorded (1890) by Dr. JKrauss, of Mergentheim, since the 
 previous lines were written. In this case a woman aged 60 
 vomited grape seeds at the end of July, which undoubtedly were 
 derived from grapes eaten during the wine harvest in September 
 or October of the previous year. 
 
 We have already described the mechanical processes by 
 which the transfer of the food from the stomach into the intes- 
 tine is efiected, and have explained the new views of Hofmeister, 
 Schutz, and von Pfungen, according to which the chief factor 
 in this part of the motor function of the organ is the con- 
 traction of the so-called antrum pylori. If a part of the 
 stomach contents do not pass continuously or by short pauses 
 into the duodenum, the constant secretion of the gastric glands 
 (and also the saliva swallowed) must cause an increase in 
 the amount of the gastric contents, unless absorption by the 
 wall of the stomach equalises or more than equalises this 
 addition. But this is not the case. Meade Smith found in the 
 frog, that when the pylorus was closed an enormous accumulation 
 of the stomach contents occurred, and v. Anrep saw the per- 
 centage of acid remain the same in dogs where the pylorus was 
 blocked by a uterine tent, although there was evidence of 
 absorption of sugar from the stomach. No important diminution 
 of the fluid contents of the stomach can result, and any loss that 
 may occur with the sugar must be compensated by the secretion 
 into the stomach. If the stomach, under normal conditions, 
 gradually empties itself, this can only happen if the quantity 
 
124 LECTURES ON DIGESTION. [Lect. VXII. 
 
 passing into the duodenum is greater than that secreted by the 
 glands. Of course this process does not go on at the same rate 
 from the beginning to the end of digestion. Although > we 
 (Bwald and Boas) observed that 400 cc. solution of starch and 
 100 cc. of oil lost respectively 220 and 60 cc. in thirty minutes, 
 Cahn found after feeding with 50 grms. powdered meat and 300 
 water that after thirty minutes there was an increase of about 
 60 CO., then a decrease, then again an increase, and finally^ 
 after two and a half hours a rapid and constant fall in the quan- 
 tity of fluid in the stomach. So that there is not a constant, but a 
 rhythmical or intermittent discharge, or as has been long accepted 
 by physiologists, a periodical relaxation of the pylorus. How 
 does this come about, and what determines the course of this 
 process ? Unfortunately we can answer this question only very 
 inadequately. Doubtless purely mechanical relations, and espe- 
 cially the pressure of the chyme forced forward by the action 
 of the muscular wall of the fundus, are of great influence. 
 But only a definitely altered part of the stomach contents, the 
 chyme, passes normally through the pylorus ; so that there must 
 be some selective power which we can attribute only to the physical 
 properties of the stomach contents, to their consistence. They must 
 become pulpy or fluid. If we pour water into the human stomach, 
 we can observe by means of a long stomach tube attached by its 
 free end to a burette, that the level of water in the stomach from 
 the first steadily decreases, and a continuous flow takes place into 
 the intestine. But in the case of digested food we have to do 
 with another important factor, its acidity. 
 
 The acidity of the chyme stimulates the muscles of the pylorus, 
 causing tonic contraction, which is only overcome by the muscular 
 contraction of the fundus or of the antrum pylori. This process 
 occurs normally at certain intervals. But it is clear that under 
 pathological conditions, by the derangement of the opposed rela- 
 tions of these two components, disturbances may occur which 
 result most frequently in a delay of the chyme in the stomach, 
 or on the other hand in its abnormally rapid discharge into the 
 intestine. 
 
 Most authors incline to the view that the emptying of the 
 stomach contents through the pylorus into the duodenum de- 
 pends, normally, upon the degree of acidity present. It is 
 obvious that the same kind of food may remain for very varying 
 
THE PYLORIC DISCHARGE. 125 
 
 periods in the stomach, as Magendie found the gastric contents 
 of horses, fed with equal quantities, varied in equal times after 
 feeding from 1 — 5 litres. 
 
 Busch, in his case of duodenal fistula, saw remains of food 
 swallowed the previous evening appear the next morning, and 
 thinks that the pylorus is generally shut during the night. 
 Many see in the increasing acidity of the stomach the cause of 
 the opening of the pylorus. Kretschy found the maximum 
 acidity in a case of gastric fistula at the seventh hour after eating, 
 and observed, cdincidently with the emptying of the stomach, as 
 might be expected, a rapid fall to a neutral reaction. Finally, 
 central influences also play their part, as we have already shown. 
 It would be of great interest to determine the point of time at 
 which the chyme begins to leave the stomach, and that at which 
 the stomach is empty. The latter has been undertaken by Leube 
 by means of siphoning the stomach contents. It is clear that 
 the fact of the completion of digestion, that is, the proof that all 
 chyme has left the stomach,: may be easily acquired in this way. 
 The water poured into the stomach will come back free from 
 cloudiness from remains of food, or with only slight traces if any. 
 At the same time it is certain, that though this experiment 
 permits us to determine the fact that the stomach is empty, let 
 us say six hours after eating, it does not inform us of the exact 
 time at which the last remains of food left the stomach, unless 
 a series of experiments are undertaken beginning with the 
 well-filled stomach and repeated at short intervals until it is 
 corhpletely emptied. But besides the difficulty of getting any- 
 one to consent to such a series of experiments, complications 
 would arise from the irritation caused by the repeated intro- 
 duction of the tube. 
 
 The commencement of the passage of the chyme into the 
 intestine is indicated by the salol test originated by Sievers and 
 myself. Salol is a combination of phenol and salicylic acid, which 
 does not undergo any change in acid fluids, whilst in alkaline 
 media, as well as by the pancreatic juice and by the agency of 
 micro-organisms, principally of the intestinal bacteria, it readily 
 splits Tip at the temperature of the body into phenol and salicylic 
 acid. Provided that the salol is given at such a time after the 
 food that the acidity of the stomach shall have become well 
 marked, it will become split up only after its entrance with the 
 
126 LECTURES ON DIGESTION. [Lect. Vm. 
 
 chyme into the intestine, and the first appearance of salicylic 
 acid in the urine must indicate the passage of food into the 
 intestine. Sievers and I have for some time recommended the 
 use of salol for this purpose. 
 
 It has, in fact, been shown by a series of experiments, and is 
 confirmed by others (Huber, Decker, Brunner, Pal) that the 
 splitting up of salol in the intestine occurs normally 47 to 75 
 minutes after the ingestion of one gramme of the drug. Un- 
 fortunately, even in the same individuals great variations occur 
 within these limits, which alter from day to day, and are ex- 
 plained by circumstances which we cannot control. Bourget has 
 found that this in part depends on the quality of the food, as with 
 pure animal food, taken with a glass of water acidulated with 
 hydrochloric acid, the reaction occurred at the ordinary time, or 
 even about 90 minutes after, whilst with a meal of fruit, meat, and 
 vegetables, it was noticed as soon as from a quarter to half an 
 hour after, which may be accounted for by in the first case a 
 very acid chyme being poured into the intestine, which required 
 a longer time for its neutralisation than a mixed diet rich in 
 organic acids which split up into alkaline products. 
 
 One can only say that it is tolerably certain that the passage 
 of the chyme into the intestine begins within the first five quarters 
 of an hour, but it is not possible to be more accurate. Klem- 
 perer endeavoured to estimate the motor activity of the stomach 
 by determining how much of a definite quantity of oil introduced 
 into the stomach had disappeared in a given time. In strong 
 and active stomachs 60 to 75 per cent, of the oil is lost, but 
 under pathological conditions it is much less. 
 
 Schmidt-Mulheim has made the very interesting observation 
 that the amount of soluble albumen and peptone (obtained by 
 expression of the meat contained in the stomachs of the animals 
 after they were killed) in the stomachs of dogs fed on meat was 
 about the same for the different hours of digestion, so that their 
 removal must proceed pa/ri passu with digestion (see also under 
 " absorption " in Ijecture XI.), but which process is involved, 
 whether absorption or expulsion, and in what way it works, must 
 freely remain still undecided. Still we know, as above stated, not 
 however with certainty, how and when the closure of the pylorus 
 yields, and the stomach contents make their entrance into the 
 duodenum. Here, obviously, psychical influences play an im- 
 
THE LIVER IN DIGESTION. 127 
 
 portant part. These are conditions wliicii in practice often enough, 
 play a not very easily determined part, and which, find their 
 anatomical basis in the connection of the vagus with the cerebro- 
 spinal centres on the one hand, and the solar plexus on the other. 
 
 We pass now to the consideration of digestion in the small 
 intestine. 
 
 The older authors saw in the small intestine nothing more 
 than a drain-pipe for the chyme, in which the chyle was precipi- 
 tated by the bile, and in which fat was dissolved and the useless. 
 residue passed on for defeecation. We may, without vanity, 
 regard with satisfaction the abundance of new facts which the 
 restless spirit of inquiry of the last decade has disclosed concern- 
 ing this important subject. Let us commence with the analysis 
 of the liver secretion. 
 
 I will shorten my task by abstaining from any detailed de- 
 scription of the minute structure of the liver, for which I refer 
 you to the new text-books of Histology. I am permitted to do 
 so, not only from the fact that histology still owes us the answers 
 to the cardinal questions concerning the origin of the bile-ducts, 
 the endings of the nerves, &c., but mainly because the recent 
 investigations concerning the functions of the liver and the 
 part they play in the organism as a whole, have shown most 
 conclusively that the balance inclines much more to the side of 
 general metabolism than to that of the digestive functions. When 
 we hear that dogs with biliary fistulse, appropriately treated 
 and nourished, remain alive a long time without injury to their 
 general health ; when we remember that biliary fistulae in man 
 exist for years, as in the observations of Fouconneau-Dufresne, 
 Walter, Oppolzer, &c. (quoted in Frerichs' Liver Diseases) ; 
 that cases of the deepest jaundice may recover without notable 
 injury to the general health — we are sorely tempted to repeat 
 anew, but in reference to digestion, the humorous epitaph with 
 which Bartholinus denied to the liver the Galenic role of the 
 blood-preparing organ: " Siste viator, clauditur hoc sub tumulo, 
 qui tumulavit plurimos, &c." 
 
 But it is not so; and Blondlot was wrong when, from his 
 observations on dogs with biliary fistulse, he denied to the bile 
 any share in the work of digestion. The bile has a definite 
 effect in digestive action, but its absence may be compensated 
 for, and, as we have seen, for a long time, by the vicarious 
 
128 LECTURES ON DIGESTION. [Lect. VIII. 
 
 action of other secretions. The liver, from its containing in- 
 soluble glycogen, is the mighty storehouse of hydrocarbons for 
 the organism, out of which the blood and tissues are provided as 
 required with grape sugar, just as insoluble starch is deposited 
 in the seeds of plants, which is changed by diastase into soluble 
 sugar and then employed in the nutrition of the cells. It is 
 also the excreting organ for a series of materials circulating in 
 the blood and consumed in the liver, the accumulation of which 
 in the blood, after destruction of the hepatic function, acts 
 poisonously; and it becomes thereby the place of origin of a 
 number of substances which pass in part as urea into the blood, 
 in part as the constituents of bile into the intestine. 
 
 But a series of facts indicate that by the formation and ex- 
 cretion of bile we are to perceive much rather the eliminatioii' 
 from the blood of certain early stages of bile than an essential 
 aid to digestion. The liver has a double role. It is an excreting 
 and a storing organ, and its use in digestion, so far as the action 
 of the bile is concerned, is subordinated throughout to the other 
 function. In the pathology of the liver, the absent or altered 
 bile has almost no effect on the digestive process ; but it is the 
 derangement arising in the general metabolism which gives rise 
 to the severe symptoms of liver diseases. However, I can only 
 indicate these relations, the discussion of which would lead us 
 too deeply into the region of tissue metabolism, to be consistent, 
 with my intention to limit myself to the description of the con- 
 stituents of the bile and its secretion. 
 
 Let us pass on to the description of the bile. 
 
 Biliary fistulse secrete a golden yellow or yellowish green, 
 clear, slightly tenacious secretion of intense bitter taste, feebly 
 alkaline reaction, and a sp. gr. of 1*026 to 1'032 — the hile. Its 
 quantity increases with digestion, reaches its maximum in the 
 fifth to the eighth hour after food (in Eosenberg's experiments 
 even in the second hour), and then falls again ; but the secretion 
 never ceases entirely, except under pathological conditions. 
 Indeed, the starving dogs in S. Rosenberg's experiments secreted 
 an increased quantity of their bile at the hours at which they 
 were formerly used to digest. The pressure under which the 
 bile is secreted is only slight, according to Picard, 50 to 60 mm. 
 water, and the secreting function is here, as elsewhere, dependent 
 upon the circulation, as the ligature of all the hepatic vessels 
 
THE BILE. 129 
 
 causes complete stoppage of the biliary secretion. The ligature 
 of the portal vein, with the artery left untied, permits the occur- 
 rence of a short continuance of secretion. Slowing of the blood- 
 current in the portal vein, which occurs after stimulation of the 
 vagus as an indirect consequence of slow respiration, and the 
 initially increased blood pressure, causes, according to Heiden- 
 hain, a transient increase in the secretion. After diabetic 
 puncture in the floor of the fourth ventricle, B. Naunyn found 
 slowing of the biliary secretion, no doubt as the consequence of 
 the altered vasomotor innervation of the liver, and the resulting 
 diminution in the blood pressure in its vessels. It is possible 
 that these and similar consequences arise in part from the con- 
 traction of the smooth muscular fibres of the bile-ducts. Thus 
 a reflex contraction of the bile-ducts occurs when the acid 
 chyme touches the papilla of the ductus choledochus, and Schiff 
 suggests that the chyme as it passes is played upon by a jet of 
 bile. But the whole subject needs more data, and those we have 
 are as uncertain as those concerning the quantity of bile secreted. 
 Thus J. Ranke observed a man with a hydatid of the liver which 
 had ruptured into the lung, who coughed up in 24 hours 652 
 grms. of bile, but this varied from 145 — 945 grms. Wittich 
 found in a woman with a biliary fistula 552 grms. ; Harley, 600 
 grms. ; Westphalen, 453 — 566 ; in dogs, much higher figures 
 are given. The bile formation often appears to be quite sup- 
 pressed ; at least cases are described, like that of von Stabell, 
 in which complete decolorisation of the faeces occurred without 
 jaundice. The action of drugs on the secretion of bile in fasting 
 animals with biliary fistulse has been studied on an extensive 
 scale by Eutherford and Vignol. According to them corrosive 
 sublimate and calomel in doses of from 0'005 to 0'05 grm. per 
 kilo, of body weight caused increased secretion of bile. Podo- 
 phyllin and benzoate and salicylate of sodium had the same 
 efiect, a conclusion supported by the recent experiments of 
 Paschkis and Eosenberg on the biliary salts of soda and on 
 the bile. In practice I have seen good results following this 
 indication from a combination of podophyllin with chelate of 
 soda. S. Eosenberg has studied in dogs with fistulas the condition 
 of the bile after the introduction of a large quantity of fat, e.g., 
 50 to 120 grms. olive oil, and found that its water and solids 
 were both considerably increased. 
 
 9 
 
loO LECTURES ON DIGESTION. [Lect. VHI. 
 
 On the other hand, it is of some practical value to note that 
 neither the so-called Durande's mixture (turpentine 1 part, ether 
 3 parts), nor Carlsbad salts had any influence on the secretion 
 worth speaking of. 
 
 The composition of the bile may be seen in the following two 
 tables. The first is the mean of two very nearly equal analyses 
 of ITrerichs and Gorup-Besanez, which were obtained (1) from 
 a young man of 22 ; (2) from a man aged 49 (decapitated). 
 The second gives, according to Hoppe-Seyler, the mean of five 
 samples of human bile obtained post mortem, in which only the 
 organic matters are estimated. They amount to somewhat more 
 than half those of Frerichs and Gorup-Besanez ; and Westphalen 
 found in the fresh bile of his patient only 2-25 per cent, of solid 
 residue, which by stagnation of the bile rose to 4 per cent. 
 Similar variations are found in other analyses, and it is no 
 wonder, for, as pathologists have long known, the concentration 
 of the bile in the gall-bladder may vary greatly within certain 
 
 limits. 
 
 I. II. 
 
 Water 84-14 Water ) g^.gg 
 
 Inorganic matter 1 -05 Inorganic matter ) 
 
 Organic matter 15'50 Organic matter 8-32 
 
 viz. viz. 
 
 Mucus and colouring matter 2'54 Mucus 1-29 
 
 Cholesterin and fat 2-95 [ Taurocholate of 
 
 Salts of bile acids 9-96 BHe galtsJ ^<"li"™ ^'^'^ 
 
 ) Glycocholate of 
 
 ( sodium 3-03 
 
 Soaps 1-39 
 
 Cholesterin 35 
 
 Lecithin 0-53 
 
 Fat ; 0-73 
 
 The inorganic constituents consist of phosphates and carbonates 
 of lime and sodium, with potassium and sodium chlorides. Under 
 organic matter, there are still to be named a not yet isolated 
 diastatic ferment, and, according to Naunyn's analysis, sugar. 
 In order to prove the diastatic capacity of bile, we must take the 
 fresh bile of an animal just killed. After long standing the 
 bile acts no longer. This property of bile appears to be not 
 constant and to be slight in all cases. Frerichs overlooked it. 
 I have not always found it, which difference I attribute, as just 
 
THE BILE ACIDS. 131 
 
 explained, to changes occurring on exposure to air. On the 
 other hand, Wittich proved its presence in fresh human bile, 
 and indeed extracted the diastatic ferment in question hy his 
 glycerine method. If fresh bile is treated with acetic acid its 
 mucus is precipitated stained with bile pigment. 
 
 We can easily perceive the mucus of the bile, quite apart from 
 its tenacity, in cases of obstruction of the gall-ducts by con- 
 cretions. There are cases of long-standing jaundice, in which 
 the gall-ducts and the gall-bladder are filled with a pale, mucous, 
 sticky fluid, which scarcely suggests bile. This mucin is in all 
 probability not a product of the liver cells, but a secretion of the 
 bile passages or of their mucous glands, as the more abundantly 
 the bile flows the poorer is it in mucus. But with slow secretion 
 a greater absorption takes place through the walls, which may 
 diminish the percentage of water while increasing the mucus, 
 so that the question as to the seat of the secretion of mucus is 
 as little decided here as in the case of the stomach. 
 
 Let us turn to the consideration of the most important con- 
 stituents of the bile, its specific acids and colouring matter, it 
 being understood that it is not my intention here or elsewhere 
 to enter into details of chemical methods and theories. For our 
 present object that would be only waste of time. Therefore I 
 pass by methods of production, chemical constitution, enumeration 
 of general reactions, &c., and keep to the facts which are 
 important to pathology. 
 
 In the bile there are two acids, or rather their alkaline salts, 
 glycocholates and taurocholates of sodium and potassium. They 
 are insoluble in ether, so that they are easily obtained from an 
 alcoholic solution of evaporated bile by precipitation with excess 
 of ether. The fine, acicular, silk-like crystals which you see 
 here, have been separated in this way, and are what was described 
 as Plattner's crystallised bile. If we prepare the acids pure, 
 and boil them with caustic potash or baryta water, they decom- 
 pose, giving up watei', into an acid-like substance, cholic acid 
 and another body which in this case has the character of a base. 
 In one case, this is glycocoll or gelatine sugar; in the other, 
 taurin. The latter is only found in bile, the former is widely 
 distributed in the animal body. Both are nitrogenous substances 
 and direct derivatives of the albuminates. Glycocoll is pre- 
 pared directly from animal gelatine. Taurin, which is one 
 
132 LECTURES ON DIGESTION. [Lect. Tin. 
 
 of the rarer substances in the organism, may be prepared syn- 
 thetically from alcohol, sulphuric acid, water, and ammonia, and 
 proves its near relationship with albuminous bodies by containing 
 a considerable quantity of sulphur. 
 
 rGIycocoU =C2H5NOi^ 
 i] Water ==^1,0 
 ICholie acid =0^ H40 O5 
 
 rGIycocoU =C2H5NOa 
 aiycocholio acid] Water ='5^0 ICje H^ NOj 
 
 lohoKc acid =C„, H.„ oj 
 
 Taurocholie acid 
 
 Cholic acid =624 H4, 0^ 
 
 Water =E, CjeH.sNSO; 
 
 ,Taurin =C2H7NS03. 
 
 Of a slightly different composition, according to H. Bayer, is 
 the still little studied cholic acid of human bile, which he calls 
 anthropocholic acid, viz., Cig Hjj 0^; it forms salts just like 
 glycocholic acid and taurocholie acid, giving the same reactions. 
 
 Besides these there are hyocholic acid, cheno-taurocholic 
 acid, choleic acid, and fellic acid, which, however, possess a 
 purely chemical interest. 
 
 We may mention a reaction of cholic acid with solutions of 
 iodine in iodine of potassium. This is a deep blue coloration, 
 and in the mixture deep blue filiform crystals may be recognised 
 with high powers of the microscope. 
 
 Respecting the sulphur in taurin, the sulphur of the bile has 
 some significance; this was found by Spiro, after very carefiil 
 investigation, to vary very much (from 1'88 to 8'41 per cent.). 
 If taurin is derived from albumen, and the so-called aether- 
 sulphuric acid of the urine has the same origin, it would be 
 interesting to estimate the excretion of each in the same indi- 
 vidual for a definite period, and to see whether both were formed 
 in equal quantities from albumen ingested, or whether they were 
 influenced by it or not. Obviously the latter is the case ; the 
 sulphuric acid excretion in the taurin of the bile is quite inde- 
 pendent of that of the aether-sulphuric acid of the urine, and the 
 two curves are nowise parallel. In other words, great quantities 
 of albumen may be destroyed and excreted in the urine without 
 notably affecting the formation or excretion of taurocholie acid. 
 We know, moreover, other facts which show that the part played 
 by the bile in the processes of tissue metamorphosis is only a 
 very slight and feeble one. 
 
 In order to obtain the bile acids by Pettenkofer's reaction. 
 
BILE PIGMENTS. 
 
 133 
 
 the biliary salts must be in the purest possible solution. By- 
 adding, drop by drop, concentrated sulphuric acid to the solu- 
 tion treated with cane sugar, in tixae there occurs a gradually 
 deepening purple coloration, provided that the temperature of 
 the fluid does not exceed 70°. The active principle of this re- 
 action has been recognised by Mylius (1887) as furfurol, a body 
 formed by the action of sulphuric acid on sugar. The following 
 method of Strassburg is of importance for medical practice, as it 
 enables us to ascertain the presence of bile acids in the urine 
 rapidly. Dip a strip of filter paper into the urine treated with 
 sugar, and dry it. A drop of sulphuric acid dabbed on the paper, 
 in the presence of bile acids, becomes after a few seconds a beau- 
 tiful violet colour, which soon becomes dark purple red, and this 
 detects 0'03 mgrm. of the bile acids with certainty. However, 
 farther experience has taught me that this is not always the 
 case; a negative result is indefinite, and in such cases it is 
 necessary to separate the bile acids (by precipitation with acetate 
 of lead and treatment with boiling alcohol). 
 
 The pathology of liver diseases has a deep interest in the 
 detection of bile acids in the urine. They played a great role 
 for a long time in the questions of hepatogenous and hemato- 
 genous jaundice, as it was believed that their presence in the 
 urine was a certain criterion of jaundice by absorption. But 
 afterwards, on the one hand, Naunyn found bile acids in the 
 urine of hfematogenous (pyaemia) jaundice, and he, as well as 
 Hohne, Vogel, and Dragendorff, found bile acids in normal urine, 
 whUe, on the other hand, Lehmann failed to find them in obstruc- 
 tive jaundice, so that the value of this sign became more than 
 doubtful, whilst recent observations have made the existence of 
 hematogenous jaundice, that is, the formation of biliary colouring 
 matter outside the liver, exceedingly doubtful. 
 
 The following is a summary of our present tolerably satis- 
 factory knowledge concerning the hile pigments. 
 
 If we shake bile that has been exposed to the air with chloro- 
 form, this takes up a green colouring matter, biliverdin. Fresh 
 bile, however, owes its golden yellow colour to bilirubin, which 
 when pure is an amorphous orange yellow powder, forming, by 
 oxidation in the air or other oxidising means, the green biliver- 
 din (formerly called cholepyrrhin or cholephain). Chemists have 
 produced a series of intermediate stages, especially biliprasin 
 
134 LECTURES ON DIGESTION. [Lbct. VIII. 
 
 and bilifuscin, and studied their spectroscopic relations and tteir 
 connections with the pigments of blood and urine, which we 
 referred to in the first lecture. Two points especially interest 
 us : the derivation of and tests for the bile-colouring matter. 
 At first sight there seems no doubt that bile pigment is derived 
 from the pigment of the blood corpuscles, heemochromogen. By- 
 injection into the circulation of a whole series of substances 
 which dissolve the blood corpuscles and set free the pigment 
 from them, we succeed in producing bile-coloured urine. Among 
 these solvents are salts of the biliary acids, solutions of hasmo- 
 globin, large quantities of water, chloroform, and ether, common 
 salt solution, glycerine, toluylendiamine, arseniuretted hydrogen ; 
 and in the same way jaundice occurs after burning and scalding, 
 after poisoning with oxalic acid, pyrogallic acid, naphthol, phos- 
 phorus, &c. ; finally, icterus neonatorum and the jaundice that 
 occurs in paroxysmal hsemoglobinuria are both due to destruction 
 of blood corpuscles. The same solution of blood pigment and 
 formation of bile pigment may occur naturally in old blood 
 extravasations, where, as you know, peculiar crystals (Virchow's 
 hsematoidin crystals) have been found, first by Virchow, later by 
 Hoppe-Seyler, also in the margin of the placenta and in the 
 fluids of cysts, while their identity with bilirubin has been ascer- 
 tained by Jafie. Moreover, this ■ formation of bile pigment or 
 bilirubin crystals has been observed in artificial extravasations 
 of blood (Langhans, Quincke), in blood injected into the abdo- 
 minal cavity (Cordua), in frog's blood kept free from putrefaction 
 (v. Eecklinghausen). On the other hand, Punke and Zenker 
 found the same crystals in old bile residue. Valentiner prepared 
 hsematoidin crystals from pulverised gallstones, and Schwanda 
 succeeded in extracting characteristic crystals from the urine of 
 a case of jaundice. Neumann found bilirubin crystals in the 
 blood of a three-days' old and probably sufl!bcated child. Finally, 
 as before remarked, Hoppe-Seyler has succeeded, by the use of 
 reducing agents, in producing from haemoglobin a body iden- 
 tical with urobilin, the colouring matter of urine. This urobilin 
 is a derivative of bilirubin, and has been prepared from it by 
 Maly, so that the origin of bile pigment from blood pigment is 
 in fact proved. The bile pigments are only the middle products 
 in a series of reducing processes which convert the blood pigment 
 into the pigment of the urine. It may, in passing, be remarked 
 
BILE PIGMENTS. 135 
 
 Here that the question whether the formation of bile pigment can 
 take place outside the liver, and its deposit in the tissues give 
 rise to a certain form of jaundice as a sort of hsematogenous or 
 anhepatogenous (Quincke) jaundice, is not yet definitely solved, 
 although there is much in favour of the view that though the 
 last stage of formation of the bile pigment takes place in the 
 liver, the material for it may be prepared elsewhere, for example, 
 in the blood by the breaking up of the blood corpuscles. Naunyn 
 and Minkowski were able to demonstrate that geese deprived of 
 their livers and poisoned with arseniuretted hydrogen, which 
 dissolves the blood corpuscles, showed no jaundice, that is, no 
 bile pigment (biliverdin) appeared in the urine, and that when 
 the poisoning preceded the extirpation of the liver the pigment 
 present rapidly diminished without any bile pigment being 
 demonstrable in the blood. Stadelmann also showed that 
 jaundice after poisoning by toluylendiamine was purely hepa- 
 togenous, and the same is true of most of the above described 
 measures which give rise to jaundice or the excretion of bile 
 pigment in the urine. Where bile pigment, that is, bilirubin, 
 is found directly in the blood, it is always in dead blood, cut off 
 from the circulation, and not in circulating blood, which may be 
 regarded indeed as anhepatogenous formation of bile pigment, 
 but cannot be called anhepatogenous jaundice ; but Neusser has 
 made some criticisms on the above-described experiments of 
 Naunyn and Stadelmann, which leave the question open as to 
 the exclusively hepatic origin of the bile pigment excreted in 
 these experiments. 
 
 This fact has such significance for the pathology of jaundice, 
 that I could not pass it over, although strictly it goes beyond 
 our proper subject. As to the role of the bile pigment in 
 digestion we can say nothing, nor do we know how or in what 
 manner it participates in the digestive process, so that I pass 
 to the second of the above points, the reactions of the bile 
 pigment. Eespecting this I may incidentally direct your atten- 
 tion to a simple test suggested by Eosenbach : a large quantity 
 of icteric urine is filtered, and the wet filter paper dabbed 
 with a drop of impure nitric acid, at the borders of which 
 comes the play of colours from red to green. Cholesterine 
 (the beautiful shining crystals of which have given rise to the 
 name " bile fat," although this body has nothing to do with fats. 
 
136 LECTURES ON DIGESTION. [Lect. VIII. 
 
 but is an alcohol) and lecithin are bodies about which we are in 
 the same state of ignorance as we are concerning the bile pig- 
 ment, so we shall be content to remind you of the solubility of 
 the lirst-named body in solutions of biliary acids and its insolu- 
 bility in water. Under certain conditions of diminution of the 
 bile-acid constituents of the bile, cholesterine is separated in the 
 form of gallstones. 
 
 If we inquire as to the functions of bile in digestion, the few 
 facts we know are quickly enumerated, but their interpretation 
 is uncertain and doubtful. Let us consider shortly what are the 
 contents of the chyme as it enters through the pylorus into the 
 intestine : — 
 
 1. All matters still undigested by the saliva and gastric juice, 
 such as starch or paste, gelatinous tissues, dissolved gelatine, 
 albumen (syntonin and native albumen) dissolved by the gastric 
 juice but not yet converted into peptone, and the isolated, par- 
 tially digested, but still not decomposed primitive muscular 
 bundles. 2. The products of digestion up to the pylorus, viz., 
 peptone, dextrose, laevulose, peptonised gelatine. 3. All matter 
 quite unchanged by saliva and gastric juice, fat, fatty acids, 
 cellulose. 4. Gastric juice or fluid, with the fluid constituents 
 not hitherto absorbed in the stomach, including mucus and 
 gastric juice. 
 
 This entire mass possesses a strongly acid reaction. The bile 
 has a very alkaline reaction, and moderates the acidity of the 
 chyme. Many maintain that it neutralises the chyme, and pre- 
 cipitates from the neutral solution the pepsin, syntonin, and 
 unchanged albumen. This is more than doubtful. If we open 
 the duodenum of an animal killed during digestion we find — at 
 least I have always found it so — the contents of intestine beyond 
 the opening of the ductus choledochus still very acid; there is no 
 trace of precipitation of albumen. In the above-mentioned case 
 of praeternatural anus I found the reaction of the secretion from 
 the fistula in a much lower part of the gut as often acid as 
 neutral. Schmidt-Mulheim and others have recently found, in 
 complete accordance with this, that the intestinal contents of a 
 recently killed digesting animal have an acid reaction. There 
 can be no good in discussing whether such a precipitation occurs, 
 for, as we shall see later on, the albuminous matter in the mass, 
 as it is precipitated by the changed reaction, is submitted to the 
 
ACTION OF THE BILE. 137 
 
 action of the pancreatic juice, which changes it at once into other 
 soluble modifications. 
 
 Much more certain is a second property of bile, which it owes 
 to the salts of the bile acids, and which concerns the emulsifica- 
 tion of fats. A good emulsion, that is, the finest possible division 
 of tke fat-drops in a more or less viscid menstruum, only occurs 
 when the fat to be emulsified contains free fatty acids, and the 
 menstruum has an alkaline reaction. Under these circumstances, 
 as Briicke showed, the slightest shake is sufficient to form a per- 
 manent and fine emulsion ; indeed, under certain mutual relations 
 between the fat, fatty acids, and an alkali, there scarcely needs, 
 as Gad discovered, any mechanical aid. A drop of cod-liver oil, 
 which always contains some free fatty acids, if placed in a watch- 
 glass with a 0'3 p.c. solution of soda, passes in a few seconds-, 
 without any mechanical mixing, by a purely chemico-physical 
 process, into a milk-white emulsion, which, as may be seen under 
 the microscope, consists of the very finest drops. But this takes 
 place only when there exists a quite definite relation of solubility 
 between the soaps formed by the combination of the alkalies pre- 
 sent with the fatty acids and the surrounding menstruum, so 
 that the disturbing precipitation of soap membranes is prevented. 
 On account of its alkaline constituents, the bile is capable of 
 forming soaps with the fatty acids ; and, secondly, it keeps the 
 soaps so formed in perfect solution. But it is too rich in alkalies 
 to effect this without dilution or partial combination of its alkalies, 
 and under certain conditions it may act so as to prevent the 
 formation of an emulsion. The conditions which are unfavour- 
 able to the formation of a good emulsion must be corrected by 
 opposing them, and for this purpose there is abundant oppor- 
 tunity in the intestine. On the one hand, it is necessary to 
 dissolve the little soluble soda and potash soaps, which are derived 
 from the salt and lime of the food, while on the other a too high 
 degree of acidity must be moderated, because both these condi- 
 tions, as Gad has shown, diminish the goodness of the resulting 
 emulsion. It is certain that the discharge of bile has an influence 
 which, if not very definite, is still very marked. Bidder and 
 Schmidt observed the proportion of the fat in the chyle of two 
 dogs, of which one had a biliary fistula : it was as 32 : 2. Schwann, 
 and after him others, maintained biliary fistulas a long time 
 without marked injury to life, but still only, as Voit pointed out, 
 
138 LECTURES ON DIGESTION. [Leot. VIII. 
 
 when tlie loss of absorbable material was compensated for by 
 increased food. Tiiis loss exclusively concerns the fat ; whilst 
 in normal animals 99 per cent, of the fat is absorbed, and only 1 
 per cent, appears in the faeces ; in animals with biliary fistnte, 
 only 40 per cent, is absorbed and 60 per cent, excreted. Roh- 
 mann, and especially Pr. Miilier, have recently investigated the 
 influence of the exclusion of bile from the intestine on the diges- 
 tion of various articles of food in the dog and man, by means of 
 careful estimation of the amount of fat and fatty acids in the 
 fasces. Miilier concluded that the absorption of starchy matter 
 was scarcely affected at all, that of albumen only slightly, but of 
 fat very much so, as in total exclusion of bile 55 to 78 per cent. 
 of it was found in the faeces, whereas in health only 6'9 to 10'5 
 per cent, can be found. 
 
 Finally, bile possesses an anti-fermentative action, and as the 
 older authors concluded, from observing the hard faeces of jaun- 
 diced patients, it is also a purgative. These properties, like 
 m.any other observations of our acute and observant forefathers, 
 have been fully confirmed by experiment. The bile acids, in 
 fact, act by inducing increased peristalsis, and Rohmann has 
 found, after creating a biliary fistula, an increase of the putres- 
 cence of the contents of the bowel and of the excretion of aether- 
 sulphuric acid in the urine, which latter indicates an increase in 
 the intestinal decompositions, whilst Fr. Miilier always found in 
 simple icterus that the combined sulphuric acid, as well as the 
 neutral sulphurs, were not importantly altered. For the eluci- 
 dation of this point further experiments are needed. But you 
 see that all these processes do not consume the bile or modify it 
 importantly, and the question now arises, what becomes of the 
 elements of the bile when they have got into the intestine ? A 
 part, e.g., the cholesterine, a fraction of the bile acids and its 
 pigment, indisputably leaves the body with the fasces. But 
 Bidder and Schmidt found in the faeces of five days the consti- 
 tuents of only four grammes of bile, with 0-38 sulphur ; whilst, 
 according to an approximative estimate, about 39-5 grammes 
 with 2-37 sulphur were passed into the intestine. Where is the 
 remainder? SchifF long ago suggested that the bile secreted into 
 the bowel underwent a sort of circulation from the intestine 
 through the vessels into the liver and back again into the bowel, 
 the same bile being secreted over and over again. But this 
 
FATE OF THE BILE. 139 
 
 view, like many others of tliis investigator, has never been pro- 
 perly confirmed, though other observers have found that the in- 
 troduction of bile or bile acids into the bowels caused an increased 
 flow of bile, while the creation of a biliary fistula and tying the 
 bile ducts caused a diminution of the bile secretion. But the 
 objection remains that an irritation may be set up in the bile 
 apparatus by the destruction of certain constituents of the blood, 
 or that the material for increase may be supplied, especially as 
 the change in the flow of bile, as Kosenberg has pointed out, does 
 not take place suddenly but gradually, whilst it ought to occur as 
 soon as the bile duct is tied. No means exist by which we can 
 trace the injected material, so as to be able to recognise it again, 
 as Schultzen and Nencki, for example, in their famous experi- 
 ments, found glycocoll depending upon methyl ; at least I cannot 
 regard as of great value the experiments of "Weiss, who found 
 glycocholic acid, which is normally absent, present in the bile of 
 dogs fed with glycocholate of sodium. 
 
 The answer to this question has been nearly reached by means 
 of an interesting series of experiments by Tappeiner. It con- 
 cerns only the bile acids, which, as I shall premise, hitherto have 
 not been found in the blood, although their presence, when in 
 large quantities, is indicated by the slowing of the pulse. On 
 the other hand, Tappeiner has found them in 150 ccm. of chyle 
 from the thoracic duct, and Draggendorf in non-jaundiced urine. 
 A part, at all events, also passes out of the intestine into the 
 vessels, and it is in the jejunum and ileum that this absorption 
 takes place. This Tappeiner has proved by the aid of an exact 
 method of estimating the bile acids. He injected solutions of 
 known concentration into ligatured portions ot intestine, and 
 after a certain time saw how much had been absorbed. This 
 showed that the solution injected into the ligatured loop of duo- 
 denum remained unchanged, whilst in the similarly treated loops 
 of jejunum and ileum absorption had taken place. But even in 
 the jejunum all the bile acids were not taken up by the intestinal 
 epithelium, but only the glycocholate of soda, and Tappeiner 
 makes it probable that the different relations of the particular 
 segments of gut depend upon a specific capacity of their epithe- 
 lium for the absorption of bile acids. 
 
 Milk and bile injected at the same time into a loop of duo- 
 deniim or jejunum behave very differently. The milk is absorbed 
 
140 LECTURES ON DIGESTION. [Leot. Vm. 
 
 and fills the vessels with milk-white chyle ; the bile, on the other 
 hand, that is, the taurocholate of sodium, remains in the intestine. 
 This experiment, interesting in itself, gains from the latter fact 
 a very special significance for the doctrines of absorption, as we 
 shall see in the proper place. 
 
 But this is all we know concerning the function and fate of 
 the bile. Little enough, when we think of the dominating role 
 which it at one time played in medicine. Moreover, we know 
 almost nothing as to the pathological changes of the bile in 
 diseases, or of the influence which changed bile exerts on the 
 digestive processes. 
 
 The subject of gallstones has been most studied. Naturally 
 those who have to do clinically with gallstones and their con- 
 sequences, know how annoying it is to have the stones not only 
 recognised, but sometimes directly under our hands, and yet 
 to have to remain powerless in their presence. If we know 
 their chemical composition, of which I shall speak directly, 
 we are in the dark completely as to their origin. As most 
 stones consist of cholesterine, which, like bilirubin-calcium, 
 is soluble in bile acids or their salts, we must believe, in order 
 to explain the formation of these concretions, that there is 
 either a diminished production of bile acids, or an increased pro- 
 duction of cholesterine. There is still another possibility respect- 
 ing their formation. If the bile, in consequence of some abnor- 
 mal process, for example, the increased production of mucus in 
 the gall-bladder, becomes decomposed and acid, or if it stays very 
 long (Thudicum), or remains in the gall-bladder, the easily 
 decomposed glycocholate of sodium splits up into its constituents, 
 forming bilirubin crystals, lime salts, and taurocholate of soda. 
 Chevreuil has advanced for their mode of production the direct 
 proof that more cholesterine is found in bile when gallstones are . 
 present. The salts deposit around a little mass of inspissated 
 mucus, or a shred of epithelium, which forms the nucleus of the 
 stone, around which the concretion forms either a homogeneous 
 mass or a laminated or radiated structure. Nine-tenths of all 
 gallstones are formed of cholesterine, they are white or bright 
 yellow, with a shining fracture, radiated or laminated, crystalline, 
 sometimes quite transparent, containing little pigment, some- 
 times yellowish brown, with a suet-like or waxy lustre on section, 
 and frequently concentrically built up. As a rule cholesterine 
 
GALLSTONES. 141 
 
 constitutes 70 to 80 per cent, of their composition. Hoppe 
 quotes an analysis of Kekule and Planta, which gave 90'1 to 90'8 
 per cent, of dry cholesterine, against 4'9 to 5*0 per cent, of loss 
 of weight. Ritter found 98' 1 per cent, of cholesterine against 
 1'5 per cent, organic and 0'4 per cent, inorganic matter. Bili- 
 rubin-calcium stones are yellowish red to reddish brown in colour, 
 often chestnut-shaped, with coarse cleavage, and easily reduced to 
 a brown powder which has no fatty feel. Bilifuscin is contained 
 in the small dark grey, almost black, facetted stones, which con- 
 tain no bilirubin or cholesterine. They consist chiefly of inorganic 
 matter, carbonate of lime, or earthy phosphates. According to 
 Ritter, such stones consist of 64'6 per cent, carbonate of lime, 
 12'3 per cent, phosphate of lime, 3'4 per cent, ammoniacal phos- 
 phate, 0'4 per cent, cholesterine, and 1"4 per cent, bile pigment. 
 Occasionally these substances may be combined differently, and 
 give rise to many varieties. Finally, we meet with cholesterine 
 stones whose surface indicates that a solution of the cholesterine 
 has occurred. This happens by means of soaps and salts of the 
 bile acids, the solvents of cholesterine, when the bile in the gall- 
 bladder is not saturated with cholesterine. We must regard as 
 a sort of psuedo-gallstones those concretions described by Teuffel 
 in isolated and atrophying portions of liver substance. 
 
 The few notices concerning the other pathological changes in 
 the bile, such as, for example, the statements of Frerichs, that 
 post mortem there have been found in the gall-bladder albumen 
 in hypersemia of the liver, and leucin and tyrosin in typhus, have 
 no great significance. In general, changes of the liver paren- 
 chyma appear to effect no special change in the bile. I may pass 
 over those changes which are found in closure of the bile-ducts, 
 as well as the excretion by them of certain toxic substances, as 
 not belonging to our subject. 
 
 Wiel. Tisch f ilr Magenkrankheiten. Carlsbad, 1877. In this is given the case 
 
 of grape seeds in a dilated stomach. 
 Kretsohy. Beobachtungen und Versuohe an einer Magenfistelkcanken. Deutsch. 
 
 ArohiT. f. klin. Med. Bd. xviii. p. 527. 
 Busch. Beitrag zur Physiologie der Terdanungsorgane. Virehow's Arohiv. 
 
 Bd. xiT. p. 140. 
 Th. Bartholini. Vasa lymphatica nuper Hafniae in animantibus inventa et 
 
 hepatis exsequise, 1653. 
 Heidenhain. Studien dcs Physiolog. Institut zn Breslan. Hf t, 2 u. 4. 
 
142 LECTUllES ON DIGESTION. [Lect. Vin. 
 
 Eoehrig. Experimentelle Untersuchungen tlber die Physiologie der Gallen- 
 
 absonderung. Wiener Med. Jahrb. 1873, p. 240. 
 J. Munt. TJeber den Einflnss senaibeler Eeizung auf die Gallenauasoheidung. 
 
 Pfliiger's Arobiv. Bd. viii. p. 151. 
 J. Eanke. Die Blutvertheilung und der Thatigkeitaweohsel der Organe. 
 
 Leipzig, 1871, cap. Tiii. 
 T. Wittioh. Zur Physiologie der mensohlioben Galle. PflUger's Archiv. Bd. vi. 
 
 p. 181. 
 Weatphalen. Ein Fall von Gallenfistel. Deutseh. Arobiv. f. Idin. Med. Bd. xi. 
 
 p. 588. 
 Harley. On a caae of bydatid diaeaae of tbe liver. Med. Cbir. Trans, p. 89, 
 
 Vol. ii. 
 Naunyn. BeitrSge zur Lebre votn Diabetes Mellitus. Eeprint from Arobiv. 
 
 f. exper. Patbologie und Pbarmakologie, 1874.. 
 Straasburg. Modifioirte Pettenkofer'aobe Probe. Pfliiger's Arobiv. Bd. iv. p. 461. 
 
 Naunyn. Beitrag zur Lebre vom loterna. Eeicbert u. dn Bois' Arobiv. 1868, 
 p. 401. 
 
 C. Lebmann. Bidrag til Laeren on gulost. Ugeskrift for Laeger, vi. No. 24. 
 
 Steiner. Ueber die bsematogene Bildung des Gallenfarbatoffa. Inaug. Diaaert. 
 Berlin, 1874. Containa a, comprehensive but incomplete expoaition of the 
 discussion concerning bEematogenous and hepatogenous jaundice. 
 
 Taracbanoff. TTeber die Bildung von Gallenpigment aus Blutfarbstoff im Tbier- 
 
 korper. PflUger's Archiv. Bd. ix. p. 53 and 329. 
 Maly. Einwirkung von H. in statu naaoendi auf Bilirubin. Annalen d. Chemie, 
 
 Bd. olxiii. p. 81. 
 Hoppe-Seyler. Binfache Daratellung von Harnfarbstoff aus Blutfarbstoff. 
 
 Beriobt. d. Deutach. chem. Gesellsohaft. Bd. vii. p. 1065. 
 Eosenbaoh. Zur TJnterauobung dea Hams auf Gallenfarbstoff. Ctrblt. 1876, 
 
 No. 1. 
 Ewald. Ueber das Verbalten dea Pistelseorets und iiber Phenol und Indioan- 
 
 aussobeidung bei einem an Anus prseternaturalis leidenden Kranken. Tir- 
 
 cbow's Archiv. Bd. Ixxv. p. 409. 
 Gad. Zur Lehre von der Pettreaorbtion. Du Bois Eeymond'a Arobiv. Bd. i. 
 
 1878, p. 181. 
 
 Tappeiner. Ueber die Aufsaugung der gallenaauren Alkalien im DUnndarm. 
 
 Wiener Sitzgsber. Bd. cxxvii. 1878, iii. Abth. 
 Eutherford. A Report on the Biliary Secretion of tbe Dog. British Medical 
 
 Journal, 1878 and 1879. 
 E. Stadelmann. Zur Kenntnisa der Gallenfarbstoffbildungen. Arch. f. exp. 
 
 Patbol. Bd. xiv. xv. and xvi. 
 
 Gerhardt. Einige neue Gallenfarbstoffreactionen. WUrzburger Sitzunga- 
 bericbte, 1881, No. 2. 
 
 Voit. Ueber die Bedeutnng der Galle fur die Aufnabme der Nahrungsmittel 
 im Darmkanal. Eeatscbrift. Milnoben, 1882. 
 
 Eohmann. Beobacbtungen an Hunden mit Gallenfiateln. PflUger's Arch. Bd. 
 xxix. p. 509. 
 
 Paachkia. Ueber Chologoga. Wien. med. Jahrb. 1884, Heft 2 and 3. 
 
 Weiaa. Oe que devient de la bile dana le canal digestif. Centrlbl. 1885, p. 121. 
 
 TeufEel. Ueber eine eigentbUmliohe Perm von LeberentzUndung (Hepatitis 
 sequestrans). Schmidt's JabrbUoher, 178, p. 289. 
 
BIBLIOGRAPHY. 143 
 
 Stadelmann. "Weitere Beitriige zur Lehre vom Icterus. Dentaohea Aroh. f. klin. 
 
 Med. Bd. 43., p. 527, 1888. 
 Fi. MilUer. Untersuohuugen iiber den Icterus. Zeitsohr. f. klin. Med. Bd. xii. 
 
 Heft 1 and 2. 
 Tisaier. Essai sur la pathologic de la secretion biliaire. Paris, 1889. 
 Minkowski and Naunyn. Beitrilge zur Pathologic der Leber und des Icterus. 
 
 Arch. f. exp. Pathol. Bd. xxi. 1886, p. 1. 
 Quincke. Beitrage zur Lehre Tom Icterus. Virohow's Arch. Bd. 95. 
 Cordua. XJeber den Eesorptionsmechanismus vou BlutergUssen. Berlin, Hirsoh- 
 
 wald, 1877. 
 Quincke. Arch. f. exp. Pathol. Bd. xix. 
 
 Neusser. Ueber Icterus. Wieu, kHn. Woch. 1889, No. 1 and 2. 
 Ewald and Sievers. Zur Pathologie und Therapie der Mageneotaaien. Therapeut. 
 
 Monatshefte, 1889, August. 
 T. Pfungen and UUmann. Ueber die Bewegungen des Antrum pylori beim Men- 
 
 schen. Centrlbl. f. Physiolog. 1887, No. 13. 
 Schreiber. Die spontane Saftabacheidung des Magens. Arch. f. exp. Pathol. 
 
 Bd. xxiv. p. 365. 
 Miller. Ueber Gahrungsvorgange im Terdauungstraotus und die dabei bethei- 
 
 ligten Spaltpilze. Deutsche med. Woch. 1885, No. 49, and 1886, No. 8. 
 Huber. Die Methoden zur Bestimmung der motorischen Thatigkeit des Magena. 
 
 Correspondenz-Blatt fUr Schweizer Aerzte, 1890. 
 Brunner. Zur Diagnostic der motorischen Insufficienz des Magens. Deutsche 
 
 med. Wooh. 1889, No. 7. 
 Decker. Zur Prage des diagnostischen Werthe des Salols, &o. Berl. klin. Woch. 
 
 1889, No. 45. 
 Klemperer. Ueber die motorische Thatigkeit des menachlichen Magens. 
 
 Deutsche med. Woch. 1888, No. 47. 
 Pal. Ueber die Terwerthung der Salolspaltung zur diagnostischen Zwecken. 
 
 Wien. klin. Woch. 1889, No. 48. 
 Klemperer and Scheurlen. Das Terhalten des Fettes im Magen. Zeitsohr. f. 
 
 kUn. Med. Bd. xt. Heft 4. 
 
144 
 
 LBOTUEE IX. 
 
 Gentlemen, — If our knowledge of the pancreas had developed 
 in proportion to the zeal which it has evoked from physiologists, 
 it would be the best known gland in the body. Regnier de 
 Graaf, as early as 1662, tied a canula in the pancreatic duct of 
 a sheep to obtain the secretion, but, according to Frerichs, he 
 appears to have been satisfied with the observation of certain 
 superficial characters of the fluid obtained. After him, almost all 
 great physiologists who have worked at the digestive processes, 
 have included the pancreas in their round of investigations. 
 Purkinje and Pappenheim, in 1836, found that the pancreas had 
 a digestive power over albuminoids ; but Bernard and Frerichs 
 first succeeded in laying the proper foundation of our present 
 knowledge concerning this gland. 
 
 The pancreas is formed on the type of the salivary glands, for 
 the circumstance that the organ has a more extended surface and 
 is not so roundly compressed into the smallest space, so that it 
 has more elongated than rounded acini, makes merely a super- 
 ficial difference. Therefore, as I may refer you to the description 
 of the salivary glands, I can limit myself to some special points 
 in the changes which the cells undergo during digestion. You 
 may remember that we could distinguish in the cells of the acini 
 of the salivary glands an inner clear mucous layer, and an outer 
 zone with granular protoplasm. The latter is coloured by 
 carmine, and during the activity of the gland spreads over all 
 the cells. Exactly the reverse occurs in the pancreas. Here 
 it is the outer zone of the cells, which lies against the mem- 
 brana propria, that is homogeneous, clear, and colours with 
 carmine ; while the inner layer next the lumen is granular, dark, 
 and not readily stained. The somewhat flattened nuclei lie at 
 the junction of the two layers. During digestion the cells shrink 
 as in the salivary glands, but the granular inner zone disappears 
 gradually, and the clear outer zone extends over the whole acinus, 
 the nuclei becoming round and large. With the aid of a special 
 
THE PANCREAS. 1<^5 
 
 apparatus, Kiiline and Lea watciied by the microscope the delicate 
 rabbit's pancreas in the living animal during digestion : they saw 
 that some tubules were smooth-bordered, others were notched, 
 the latter change being due to the activity of the particular 
 acinus. These investigators could confirm the disappearance of 
 the granular layer, which is described as Bernard's granular layer", 
 as we have stated, following Heidenhain, and we may say with 
 the latter : " During their physiological activity a very extensive 
 exchange takes place in the cells ; consumption of matter inside, 
 preparation of matter outside ; the inner converting the granules 
 into the secreting elements, the outer employing the nutritive 
 materials to form a homogeneous substance, which on its side, 
 later on, is transformed into granular matter." I can confirm 
 these statements, at least for the two extreme conditions of fasting 
 and digesting animals, although I have not found the distinction 
 between active and passive glands so striking as, for instance, in 
 the stomach. Meanwhile, I will not omit, in reference to the 
 previously discussed question (see p. 35, et seq.) as to the new 
 formation of cells during the activity of the gland, to draw 
 your attention to the fact that neither Kiihne nor Heidenhain, 
 the latest and most trustworthy investigators in this region, 
 speak of a new formation of gland cells during digestion. It 
 is probable that the secretion from the cells takes place only in 
 that side of the cells lying next to the lumen of the duct. At 
 least Kiihne made the interesting observation that blood cor- 
 puscles which get between the cells and the membrana propria 
 when a dilute solution of blood is injected under high pressure 
 into the duct, are not dissolved, whilst they soon disappear in 
 the larger passages. Between the acini of the pancreas there 
 extends a loose connective tissue in which ramify the blood- 
 vessels and nerves. The former surround the individual acini 
 with capillary loops, the latter are distributed as non-meduUated 
 fibres in the membrana propria of the tubules. The pancreas 
 is entirely dependent in its function upon the circulation. The 
 gland of a fasting dog is flabby, whitish or yellowish ; while 
 during digestion it swells and has a beautiful rosy colour. 
 Here, too, during the activity of the gland the venous blood 
 runs out of a bright arterial red colour, and, according to 
 Kiihne, there occurs a capillary and venous pulse, with dilatation 
 of the capillaries. What nerves serve as bearers of these 
 
 10 
 
146 LECTURES ON DIGESTION. [Lect. IX. 
 
 digestive influences is meanwhile only incompletely made out, 
 and there is scarcely anything known of their connections with 
 the secreting cells. Bernstein found that centripetal stimu- 
 lation of the vagus stopped secretion, a fact which harmonises 
 with the discoveries of Weinmann and Bernard that during 
 vomiting the pancreatic secretion stops, whilst peripheral stimu- 
 lation of the vagus or section of it remains without any effect. 
 If this is so, we should expect to find a system of independent 
 ganglia, such as Goltz describes in the stomach ; and as smooth 
 muscular fibres have been as a rule only sparingly seen, the 
 increase of secretion obtained by Kiihne by direct faradisation of 
 the gland is probably to be attributed to the stimulus of such 
 ganglia. These things, however, are very diificult to decide, 
 because we are not in a position to observe all the conditions of 
 the pancreatic secretion; and, besides, the gland itself appeal's 
 to be exceptionally sensitive, and rapidly gives evidence of the 
 slightest irritation by changes in its secretion. In successful 
 fistula, a common operation in recent times, but which we cannot 
 discuss here, it is found that the secretion persists apart from 
 digestion, whilst soon after food has been taken a clear, somewhat 
 viscid and slightly gelatinising secretion takes place, the quantity 
 and solid constituents of which vary very much, but so far as the 
 latter are concerned, these generally increase as the secretion 
 diminishes. I have obtained at the same period of digestion in 
 about equally large dogs, fed at the same time, sometimes 
 copious, sometimes quite scanty secretion, without being able to 
 assign any cause for this difference. Still the absolute amount is 
 never very great. Bernstein found in the dog 2 — 15 ccm. in an 
 hour, but I have never obtained more than at most 5^ — 6 ccm. in 
 the same time. Frerichs, however, could collect 25 ccm. in three- 
 quarters of an hour from an ass. The secretion is moreover, like 
 that of the salivary glands, influenced by certain poisons, and 
 according to the statements of Nussbaum pilocarpine and mus- 
 carin increase it, eserine (physostigmin) diminishes it, whilst 
 atropine, which acts so energetically on the salivary glands, has 
 no effect. The secreted fluid is, in my experience, always clear, 
 rather thick, free from colour.or smell, and of an alkaline reaction, 
 only clouded at first by the products of the irritation of the duct. 
 Huete'r found, in the dilated canal of the pancreatic duct which 
 had been occluded by carcinoma, an accumulation of strongly 
 
PANCKEATIC FERMENTS. 147 
 
 active secretion which contained peptone, but no albumen or 
 sugar, and was composed of 24 per cent, solid matter, of which 
 17"9 per cent, were organic and 6'2 per cent, inorganic. Ellen- 
 berger and Hofmeister estimated the water of the pancreatic 
 juice of the horse to amount to 98 per cent. ; the organic and 
 inorganic matter, chiefly the chlorides of sodium and potassium, 
 were present in the remainder in equal parts. The quantity of 
 the solid constituents varies from 3 — 10 per cent., which includes 
 the ordinary inorganic salts, albuminous bodies (?) and the specific 
 ferments of the juice, which stamp it as an entirely special secre- 
 tion. Of these, the pancreatic juice does not include one, but 
 three, which certainly have not yet been obtained pure, but are 
 recognisable by their actions with the greatest distinctness. 
 They are (1) diastatic, (2) albumen-dissolving, and (8) fat-split- 
 ting ferments. Just as in the case of pepsin, the pancreatic 
 ferments, which collectively are called pancreatin, may be ex- 
 tracted from the gland by infusion with water, glycerine, salicylic 
 acid, bicai'bonate of soda, &c., the albumen-dissolving and 
 diastatic ferments being most readily obtained ; the fat-splitting 
 ferment is more difficult to prepare, and seems to be easily de- 
 composed. By precipitation with alcohol and drying the preci- 
 pitate, we obtain the ferments in the form of a white amorphous 
 powder. 
 
 Concerning the diastatic ferment, which was already known to 
 Valentin and Prerichs, we know only that it is equalled, not to 
 say excelled, in activity by no other ferment. The smallest 
 amount of fresh pancreatic juice at the body temperature changes 
 starch paste almost immediately into sugar, or rather into dex- 
 trine, maltose, and (a little) sugar. Cane sugar, and a nearly 
 related hydrocarbon, inulin, do not become changed, as I can 
 confirm for the former. Zweifel and Korrwin failed to find 
 the ferment in the pancreas of newly-born children, but I have 
 been able to obtain a perfectly active extract from the pancreas 
 of a puppy three days old. Purkinje and Pappenheim as early 
 as 1836 stated that the pancreas digested albumen; Claude'' 
 Bernard first observed that coagulated albumen was dissolved by'; 
 pancreatic juice ; Corvisart established the peptonising properties 
 of the secretion, the relations of which to albuminous bodies were 
 later on studied by many workers, in Germany chiefly by Kiihne 
 and Heidenhain. The action of the pancreatic juice on albumens 
 
148 LECTURES ON DIGESTION. [Lect. IX. 
 
 takes place freely only in alkaline or neutral solutions, slowly 
 and laboriously in feebly acid fluids. Consequently, the albumen 
 does not swell as in acid gastric juice, and become converted into 
 syntonin, but shrinks and remains a longer time coherent, and 
 dissolves after having been previously converted into another 
 modification, globulin, insoluble in water. The final soluble 
 modification is a body resembling pepsin-peptone in all its reac- 
 tions. So that I can refer you for the details of pancreas peptone 
 to the description already given of stomach peptone. 
 
 Kiihne has prepared from the pancreatic tissues, by the aid 
 of a very complicated method, a body which he regards 
 as the pure ferment and calls "trypsin." But its purity is 
 doubtful, especially because this "trypsin," according to its 
 reactions as given by Kiihne, must be mixed in no small 
 degree with albumen or some nearly i-elated body. However, 
 the albumen-dissolving ferment is now generally designated 
 " trypsin." 
 
 According to Kiihne, the digestion of albumen by trypsin 
 passes through two stages: in the first, the albumen is con- 
 verted into peptone ; in the second, one-half of the peptone, 
 , which he terms " hemi-peptone," is further decomposed in a 
 ' similar way, while the other remains as " anti-peptone," which 
 , undergoes no further change. But this is the place to review the 
 ( relations of albuminous bodies to these peptic or tryptic pro- 
 cesses which have been only briefly referred to earlier. We 
 have already seen that Kiihne and his pupils, especially 
 E. Neumeister and Chittenden, who have pursued the same 
 current of investigation as their teacher, find that the products 
 formed in the digestion of albumen by pepsin and hydrochloric 
 acid are distinguished from one another by their behaviour with 
 concentrated hydrochloric acid, saturated solutions of common 
 salt and ammonium sulphate, to -dialysis, with weak solutions 
 of acetic acid, and acetic acid saturated with common salt, as 
 well as their solubility on : heating and the result of the biuret 
 reaction. Those different, but very closely allied bodies, which 
 we speak of under the common name of albumoses, but which 
 may be divided, as previously stated, into protalbumoses, deutero- 
 albumoses ■ (soluble in distilled water), and heteroalbumbses 
 (insoluble in distilled water) — ^hetero- and prdtalbumose pre- 
 cipitated by common salt in neutral solution, deuteroalbumose 
 
TRYPSIN DIGESTION. 149 
 
 by common salt and acidulation — are converted into pep- 
 tone bott by peptic and tryptic digestion, and up to the 
 present, as I have already remarked, no chemical or physical 
 reaction has so far been discovered to differentiate the peptones 
 so formed. They are distinguished in no way from the peptones 
 formed directly by trypsin from albumen, without any previous 
 gastric digestion. 
 
 However, peptones, like albumoses, may be divided into two 
 groups, distinguished by their varying resistance to certain 
 chemical actions, some being readily transformed by prolonged 
 digestion into further products of conversion, such as amidic 
 acid, leucin, and tyrosin, the others remaining unchanged. This 
 has led to the view, already suggested by the investigations 
 of Meissner and Schutzenberger, that in the peptonisation of 
 albuminous bodies a splitting up of the albumen molecule takes 
 place, forming two different portions, one more resistant and 
 one easily deconiposed, of which the first is called by Kiihne 
 the anti-group, the second the hemi-group ; so that there exists 
 in the albumen molecule one component to be described as hemi- 
 albumen, another as anti-albumen, out of which are derived 
 both series, the hemi-albumoses and hemi-peptones, and the anti- 
 albumoses and anti-peptones. The hemi-albumoses comprise 
 the above-named proto- deutero- and heteroalbumoses. By 
 digestion with pepsin and hydrochloric acid, however, an anti- 
 albumose is also formed, that is, a body which by further peptic 
 digestion becomes an anti-peptone. But if these anti-albumoses 
 are subriitted to tryptic digestion, they form next a body called 
 anti-albumide, which is affected very little or not at all by 
 gastric juice, but, nevertheless, becomes anti-peptone ; con- 
 sequently, this anti-albumose allows itself to be converted into 
 anti-peptone in two ways, by peptic and by tryptic digestion, 
 but in each of these ways by means of other intermediate 
 products. In the products of prolonged gastric digestion we 
 find hemi-peptone as well as anti-peptone, so that Kiihne has 
 described this mixture as amphopeptone. 
 
 Not space only, gentlemen, forbids me to go farther into 
 these conditions, for these investigations are chiefly interesting 
 from a physiological point of view, and consist rather of 
 the views of one very eminent investigator than of generally 
 recognised facts. What has been said should suffice to give 
 
150 LECTURES ON DIGESTION. [Lect. IX. 
 
 you some acquaintance witii these views and theories when 
 you meet with them in the course of your reading. So much 
 is certain, that the pancreatic digestion is not concluded with 
 the formation of peptones. If we mix an albuminate, or, best 
 of all, fibrine, with pancreatic juice or gland extract at the 
 body temperature, and salicylic acid solution, with the addition 
 of 1 per cent, thymol — which, as Kiihne has shown, does not 
 specially injure the action of trypsin — according to the activity 
 of the extract employed we jSind after a longer or shorter 
 time other bodies together with the peptones. These one would 
 at first ascribe to putrefaction of the albumen, but the digesting 
 mixture shows nowhere any trace of putrefaction by smell or 
 contents (bacteria, vibriones). These bodies are leucin, tyrosin, 
 hypoxanthin, asparaginic acid, and cinnamic acid. On the 
 other hand, if we have employed a feebly alkaline or neutral 
 solution, we soon find a faint putrefactive odour, with develop- 
 ment of bacteria and other signs of putrefaction, and, in addition 
 to the above-named substances, the further products of putre- 
 faction, albumen, ammonia, sulphuretted hydrogen, hydrogen, 
 and carbonic acid. It is not easy to decide clearly in this case 
 when putrefaction begins and the normal digestion ceases, unless 
 we can employ, as Hiifner has done, quite special precautions 
 and preservatives against the entrance of putrefactive organisms. 
 But while excluding all putrefactive ferments, he obtained 
 peptone, leucin, and tyrosin — he did not look for hypoxanthin, 
 asparaginic acid, and further products — as the result of the 
 normal physiological pancreatic digestion, to which, according 
 to other authors, hypoxanthin, asparaginic acid, and cinnamic 
 acid (Salkowski, Salomon) may be added. Hiifner also suc- 
 ceeded by another means in proving the same bodies to be 
 products of the physiological pancreatic digestion, and there- 
 fore the remarkable fact is made certain, that those bodies 
 which we meet with in ordinary putrefaction of albumen, and 
 which we may derive by chemical agents from fresh albumen, 
 are formed by the normal action of " trypsin." 
 
 Nencki has performed similar experiments with gelatine to 
 those of Hiifner with albumen, and has proved the formation 
 of gelatine-peptone, which in its reactions scarcely difiers from 
 albumen peptone, as well as the formation of glycocoll, gelatine- 
 sugar, a body formed in the decomposition of gelatine by 
 
TRYPSIN DIGESTION. 
 
 151 
 
 sulphuric acid. The pancreatic digestion in the intestine, as 
 in the retort of the chemist, does not remain stationary at the 
 " normal digestive products," but tends more or less to form 
 the so-called putrefactive products which we shall repeatedly meet 
 with in the description of the digestion in the small and large 
 intestine. If I were to give you a table of the action of the 
 pancreas on albumen and gelatine, similar to that for pepsin, 
 leaving out chemical details and accepting Kiihne's views, it 
 would take the following shape : — 
 
 Albumen + Trypsin (Pancreatin) + Soda Solution of 1 per cent, form 
 at the body temperature first Globulia insoluble in water, and then 
 
 Hemipeptone 
 
 Antipeptone 
 
 Leucin 
 Normal Tyrosin 
 DigestiveJ Hypoxanthin 
 Products I Asparaginic Acid 
 (^Glycocoll 
 
 Indol 
 Phenol 
 Fatty Acids 
 Ammonia 
 Sulph. Hydr. 
 Hydrogen 
 Carbonic Acid 
 
 Putrefactive 
 Products 
 
 It scarcely needs to be mentioned that the occurrence of the 
 bodies described as products of putrefaction is contemporaneous 
 with the development of bacteria and micrococci, and is an 
 almost universally admitted result of them. These organisms 
 are taken up with the food, and find in the intestine a favour- 
 able nidiis for their development. It is certain they are not 
 pre-formed in the tissues, as some maintain, but when they 
 are found, as by Nencki. in fresh pancreas, they have got in 
 by chance from the intestine. I have often examined the fresh 
 pancreas of dogs and rabbits just killed, and have never found 
 bacteria or micrococci. The experiments of Hiifner, already 
 referred to, show, moreover, that these bodies have absolutely 
 nothing to do with the products of pure pancreatic digestion, 
 so far at least as concerns the formation of leucin and tyrosin. 
 
 There is a remarkable observation of Liversedge, that a 
 pancreas completely exhausted by glycerine, after exposure for 
 some time to the air, again yields an active diastatic glycerine 
 extract. He concludes : " That there is in the pancreas a 
 substance inactive in itself, but which is converted by a process 
 
152 LECTURES ON DIGESTION. [Lect. IX. 
 
 of decomposition into a ferment," just as the glycogen of the 
 liver, after the death of the animal, is converted into sugar. 
 Heidenhain found further that the glycerine extract of fresh 
 pancreas contained only a trace of the albumen-digesting fer- 
 ment, but, on the contrary, a body which in a watery infusion 
 of the gland or by simple exposure to the air changed into the 
 active ferment. He called it "zymogen," after analogy with 
 glycogen, that is, the preceding stage of the ferment pre-formed 
 in the pancreas, but not yet forming the actual ferment. He 
 and his pupil Lewaschew have proved that it is changed 
 into the specific ferment most easily in warm and acid watery 
 solutions, much slower in neutral or alkaline solutions, and not 
 at all in glycerine. 
 
 Eeady-formed trypsin appears to be only exceptionally present 
 in the gland, and the active ferment is formed at the moment 
 of secretion, perhaps under the influence of a formation of acid 
 such as is developed in muscle by its action, and as may be 
 believed from the experiments of Podolinsky, by the agency 
 of the oxygen of the blood ; otherwise, we know that there is a 
 previous stage of ferments, a zymogen, not only in the sub- 
 maxillary gland, but in the stomach, where it occurs as pro- 
 pepsin or pepsinogen, and as a previous stage of the rennet 
 ferment. The diiference between the latter and the pancreas 
 appears to be that in this only protrypsin is normally present, 
 whilst in the stomach propepsin and pepsin occur together. 
 But we are here in the region of conjecture, because this 
 anomalous type is by no means differentiated with certainty. 
 The process itself is doubtless of deep significance to the vitality 
 of the gland, perhaps a means of limiting the expenditure of 
 its vital action, but we can only frame hypotheses, and can 
 form no definite conclusions. Later on, under absorption, we 
 shall have occasion to return to these inquiries, which un- 
 fortunately leave many gaps unfilled, as they have extended only 
 to the tryptic action of the pancreas, and take no account of its 
 fat-splitting and emulsifying functions. 
 
 Finally, Lindenberg has made a remarkable statement not 
 in harmony with the property of the pancreas to digest best in 
 alkaline solutions, according to which trypsin digestion, in 
 accordance with the conclusions of other workers, was found to 
 be interfered with or quite prevented in solutions of O'Ol to O'l 
 
THE FAT-SPLITTING FERMENT. 153 
 
 per cent, hydrochloric acid, but was not only not delayed by 
 acetic acid, and especially by lactic acid, but was actually 
 hastened. By the simultaneous use of NaOl, bile and lactic 
 acid up to 0'02 per cent., this action reached its maximum. 
 
 As in the intestine great quantities of lactic acid are formed, 
 partly normally, partly abnormally, and as also common salt 
 and bile are present, this condition is of great significance for 
 the action of trypsin. So far as I know, Lindenberg's statements 
 have not at present been confirmed ; moreover, Ellenberger and 
 Hofmeister have stated that tryptic digestion is arrested by 0'3 
 to 0-4 per cent, of lactic acid. The third, the fat-splitting ferment, 
 " steapsin," has not yet been isolated, and is only recognisable 
 in the action of the original juice or in an extract of intestine. 
 It is best demonstrated with quite fresh juice and a neutral 
 fat, which has been treated with a few drops of alkaline,, slightly 
 violet-coloured alcoholic solution of aniline purple. If we warm 
 the whole some time in a water-bath, the violet solution of fat and 
 alcohol becomes yellow by the formation of fatty acids. Glycerine 
 and a fatty acid are formed according to the following formula, 
 for which I take ordinary fat, or tallow : — 
 
 Tristearine + Ferment + Water:=Grlycerine + Stearic Acid. 
 
 CA(Ci, H~C00H)3 +3H,0=C3H5(OH)3+(C„H35COOH)3 
 
 On the significance of this formation of fatty acids I have 
 already had the opportunity of remarking when speaking of the 
 action of bile. Their formation takes place slower than that of 
 sugar and probably of peptone. Finally, we must consider the 
 emulsifying action of the secretion, which was described and 
 given an important place by 01. Bernard. "We have already con- 
 sidered the emulsification of fat by bile, and the conditions under 
 which it occurs. Saliva, blood serum, and other more or less 
 mucous and viscid fluids emulsify fat, but the results are not 
 stable, the droplets soon running together, and this happens 
 very quickly if an acid or acid gastric juice is added to the 
 emulsion. The pancreatic emulsion alone remains stable in the 
 presence of a strong acid reaction, and as for the formation 
 of a good emulsion, the presence of free fatty acids, as we have 
 seen, is necessary, we see the great importance in this, as 
 well as in other respects to be described later on, of the fat- 
 
154 LECTURES ON DIGESTION. [Lect. IX. 
 
 splitting ferment of the pancreatic juice. 01. Bernard assigned 
 to this property of emulsification of fat, a very important value 
 in the digestion of fat. His views, which were subsequently 
 repeatedly attacked and called in question, have recently been 
 entirely confirmed by the careful and thorough experiments of 
 Abelmann, who employed animals in which the pancreas had 
 been completely extirpated. 
 
 Many experiments have recently been made with the view to 
 make use of the pancreatic secretion for therapeutic purposes, 
 and quite a number of "pancreatine" preparations have been 
 manufactured claiming to possess sometimes all the properties 
 of pancreatic juice, sometimes only some of them, but always 
 its tryptic action. Unquestionably it would be of great 
 therapeutic value to supplement artificially the failing function 
 of the pancreas, where we can diagnose it, by introducing such 
 '• pancreatines " into the intestine. But the difficulty is, as was 
 shown by Kiihne and afterwards by myself, that trypsin is 
 destroyed by gastric digestion, whilst it is just this part of the 
 triple pancreas ferment which is best prepared artificially. 
 Engesser believed he had obtained a preparation by pulverising 
 the gland dried in vacuo, which contained protrypsin without 
 any trypsin. This would pass unchanged through the stomach, 
 and its action would be developed first in the intestine by 
 conversion into trypsin. This idea is, however, untenable, as his 
 " pancreas powder " is, as I have shown, destroyed by digestion 
 with gastric juice, and the method employed by him of treating 
 it is just the best for converting protrypsin into trypsin. Unna 
 has attempted, by means of his so-called intestinal pills, to 
 introduce trypsin into the duodenum coated with keratine, so 
 as to be proof against the action of the gastric juice. Keratine, 
 the substance of horn, is soluble, not in acid, but in alkaline 
 fluids, so that the coating of keratine would remain unchanged 
 in the stomach, but would be dissolved in the bowels, and the 
 pancreatine (rubbed up with fat) be free to act. This pro- 
 ceeding, though well thought out (I had tried the same thing 
 myself with water-glass) sufiers from not one, but two Achilles' 
 heels. 
 
 Firstly, the pills imbibe water, in spite of the coating of fat and 
 keratine. After some stay in the warm contents of the stomach 
 they swell up, become torn, and are attacked by the gastric juice. 
 
PANCREATINE PREPARATIONS. 155 
 
 Secondly, the reaction of the contents of the small intestine is 
 not, as we have seen, always alkaline enough to dissolve the 
 pills in the duodenum, so that I have repeatedly found them 
 as hard as a stone and quite unchanged in the faeces of my 
 patients. If, however, Engesser's powder or Unna's pills appear 
 to benefit the intestinal digestion in many cases, this may be 
 because the insufiicient gastric digestion has altered these 
 preparations either very little or not at all. Moreover, there 
 is in the market a " keratinum pepsino paratum," by Merk, 
 which is not affected by acid gastric juice, because it has 
 been previously deprived, by means of pepsin and hydrochloric 
 acid, of every part of it soluble in the stomach. But even 
 in cases where the hydrochloric acid secretion in the stomach 
 was deficient, and the peptic digestion consequently a failure, 
 I have not obtained good results with pancreatic preparations. 
 We allowed two patients suffering from deficiency of hydro- 
 chloric acid to take different preparations of pancreatine from 
 different makers after a moderate meal of white bread and 
 water, without observing any improvement in digestion ; so 
 tliat possibly there are other factors which interfere with the 
 action in the stomach of these artificial preparations which 
 digested actively enough in an incubator. In this case, one 
 was a neurasthenic aged thirty ; the other was a man aged 
 fifty-three, with commencing cancer of the stomach and a 
 palpable tumour. 
 
 Another way in which pancreatine may be employed is by 
 allowing it to digest certain foods in an incubator, and so to 
 prepare a sort of invalid's food. This plan is especially followed 
 by Dr. Roberts of Manchester, and milk peptonised in this way 
 is recommended by him. The milk is diluted with a fourth 
 part of water, some soda, the necessary quantity of pancreatic 
 ferment is added — Roberts employs a " liquor pancreaticus " made 
 by treating fresh pig's pancreas with dilute alcohol — and the 
 whole is allowed to remain at the body temperature for from an 
 hour to an hour and a half. It is then boiled to check further 
 fermentation, when a preparation is obtained of a slightly dull 
 golden colour, with layers of fat on the surface like the cream 
 of fresh milk. The taste is strongly bitter, which may be di- 
 minished by adding cream. In the same way we may peptonise 
 gruel, sago, arrowroot, and the like. 
 
166 LECTURES ON DIGESTION. [Leot. IX. 
 
 By means of Engesser's pancreas powder, I have frequently 
 prepared peptonised milk, and I reported on it at the Balneo- 
 logical Congress in Berlin for 1 881 . Most patients objected to the 
 bitter taste, and in the long run lost all appetite for it ; but this 
 objection is removed with respect to the preparation called 
 "Voltmer's Mother's Milk," now in the market, in which, by 
 the addition of cream, the taste is corrected and could scarcely 
 be distinguished from fresh milk. This preparation may be 
 employed for some time as a substitute for pure milk. Since 
 we possess the peptone preparations of Sanders-Ezn, Adamkiewicz, 
 Kemmerichs and Kochs, Hoss and others, there is scarcely any 
 need to prepare peptonised milk. The suggestion of Dobell, 
 to employ the fat-splitting and emulsifying action of the 
 pancreas, appears to be much more useful. For this purpose 
 a fresh well-cleaned pancreas is pounded in a mortar with one 
 and a half times its weight of distilled water, and digested half 
 an hour at the temperature of the body, then poured through a 
 cloth, and the filtrate shaken with oil or fluid fat. In this way 
 an exceedingly fine emulsion is formed, which remains intact 
 after treatment with pepsin and hydrochloric acid for forty- 
 eight hours. I have had no opportunity of experimenting with 
 it, but Robin has stated that the pancreatic infusion made by 
 digesting the fresh pancreas in water, and subsequent filtering, 
 forms when shaken with oil an emulsion which will resist putre- 
 faction for a month, and which is caused by the formation of 
 alkaline compounds of the fatty acids. 
 
 You see from all this, gentlemen, that our knowledge of the 
 nature of the pancreas and its juice is not so insignificant, and 
 we are quite in a position to analyse its action. Would it were 
 so with its pathology ! But on this point we can only advance 
 vague notions, if we no longer regard the pancreas as the cushion 
 for the full stomach, like Vesalius ; or as the cause of hypo- 
 chondriasis, ague, and other fevers, like Riolan, Sylvius, and 
 Hofiinann. We know certainly some morbid changes in the 
 gland. Thus we know that occlusion of the pancreatic duct, which 
 generally occurs from tumours in the head of the pancreas, 
 rarely from parasites or foreign bodies, may lead to dilatation 
 of the duct, to cyst formation, called, by Virchow, ranula pan- 
 creatica, and to atrophy of the gland substance, which Pawlow has 
 recently produced by experimental ligature of the duct. Such 
 
DISORDERS OF THE PANCREATIC DIGESTION. 157 
 
 cysts may quite exceptionally attain to an enormous size, one 
 case observed by Bozemann being mistaken for an ovarian 
 tumour, and only in the course of the operation was it dis- 
 covered that the tumour was connected with the pancreas. 
 A more or less extensive part of the gland substance may 
 become destroyed, chiefly by cancerous new formations, or by 
 fatty degeneration, and hsemorrhages result in the substance 
 of the gland, with gudden or gradual death to the individual. 
 Inflammations, abscesses, &c., occur in the gland, but we know 
 actually nothing of the efiect of these on digestion or metabolism. 
 As the first consequence of the abolished function of the pancreas, 
 we notice failure to absorb fats. In fact, Brunner saw the 
 intestinal contents dry up and become fatty after extirpation 
 of the pancreas ; and Bright noticed, in 1832, a peculiar fatty 
 character of the faeces which occurred in a case of degeneration 
 of the pancreas and ulceration of the duodenum. Similar 
 observations were, later on, again described; for example, 
 recently by Ziehl and Le Nobel. Ziehl states, that in his case, 
 in which there was simultaneous closure of the common bile 
 duct and the pancreatic duct with jaundice, the silver grey 
 fgeces presented numberless fat crystals under the microscope, 
 though to the naked eye they looked like ordinary icteric stools. 
 On the other hand, Le Nobel observed that the f^ces always 
 contained much fat when fatty food was taken ; and Nothnagel, 
 in his extensive investigation of faeces, long ago showed that 
 needles and bundles of fat crystals, and frequently even droplets 
 of fat, are to be seen in quite normal faeces. Moreover it is 
 quite certain that cases are to be observed of degeneration of the 
 pancreas or closure of its duct without fatty alvine evacuations. 
 I myself have published two such cases in a dissertation by 
 Sauter, where the ductus choledochus was closed by a tumour, 
 and the flow of bile into the intestine was prevented. Litten, 
 Hartsen, and Fr. Muller have observed cases of disease of the 
 pancreas without fatty stools. In the two cases described by 
 the last-named author, there was in one case atrophy, in the 
 other a cyst of the head of the pancreas, but in both there was 
 little fat in the faeces. Moreover, this increase of fat in the 
 stools is by no means a necessary attribute of pancreatic diseases, 
 nor has it when present any certain diagnostic value, because 
 the same phenomenon, according to English authors, occurs in 
 
158 LECTURES ON DIGESTION. [Lect. IX. 
 
 ulceration of the duodenum. The influence of disordered se- 
 cretion of pancreatic juice on the digestion of starchy matter 
 and meat has only been studied in individual cases and not 
 methodically. Whilst Langendorff, after tying the pancreatic 
 duct in pigeons, found the digestion of carbo-hydrates greatly 
 affected, Fr. Miiller in his cases, referred to above, could only 
 find traces of starchy matter in the faeces, and inferred there- 
 from that the digestion of carbo-hydrates took place normally. 
 On the other hand, he, as well as Le Nobel, found an increase 
 of muscular fibres in the stools, which indicated a limitation of 
 the digestion of albumen. We have obtained a better insight 
 into all these relations by means of the recent experiments of 
 Abelmann in the Strasburg Klinik. We shall see directly that 
 Minkowski and v. Mering have succeeded in keeping dogs 
 alive for weeks after complete extirpation of the pancreas with 
 removal of the entire gland. In one of the animals so operated 
 on, Abelmann carried out a very careful series of feeding 
 experiments with meat, bread, and fat, which gave the following 
 results : In the absence of pancreatic juice, about 44 per cent. 
 of the albumen was absorbed ; a little more, namely 54 per cent., 
 was absorbed when a small piece of the gland was preserved, 
 though there could be no direct flow of its secretion into the in- 
 testine ; but when fresh pig's pancreas was given with the food, 
 it reached 74 to 78 per cent., whilst an artificial preparation, 
 " pancreatinum purum," had no effect. The starch was chiefly 
 absorbed, although a portion, from 20 to 40 per cent., was not 
 converted into sugar. The neutral fats were not absorbed at 
 all, but a steatorrhoea occurred, which must have been caused 
 by the absence of the pancreas, as it disappeared when pig's 
 pancreas was given with the fat. Notwithstanding the fat was 
 split up, to the extent of 30 to 80 per cent., so that he found in 
 the fseces chiefly fatty acids and only a small quantity of soaps, 
 a fact of the greatest significance for the absorption of fat. 
 Emulsions of fat in the shape of soap and gum emulsions were 
 not absorbed ; while, on the other hand, natural emulsions, such 
 as milk, were assimilated to the extent of 53 per cent. 
 
 These figures were all somewhat more favourable when the 
 pancreas was only partially extirpated, and this is all the more 
 remarkable as the flow of secretion into the intestine was com- 
 pletely excluded. We must accept the possibility that active 
 
DISORDERS OF THE PANCREATIC DIGESTION. 159 
 
 agents passed into tlie intestinal canal by some otker way, 
 perhaps by a vicarious excretion with the other intestinal juices. 
 Still, we must maintain a certain reserve in the face of these 
 statements, and hold that, in spite of Abelmann's interesting 
 experiments, the question is still open. 
 
 While hitherto there have been as great differences of 
 opinion respecting the relations of the pancreas to glycosuria 
 as to the digestion of fat, the already-mentioned experiments 
 of Minkowski and v. Mering have greatly advanced our know- 
 ledge in this respect. Cantani, indeed, long ago ascribed 
 diabetes to a disease of the pancreas. Bright, and afterwards 
 Frerichs (who, even at the time he wrote his " Clinical History 
 of Liver Diseases,'' had observed out of nine cases of diabetes 
 five with atrophy or fatty degeneration of the pancreas), pointed 
 out the connection between disease of the pancreas and diabetes. 
 Cantani has found in four out of five cases undoubted fatty de- 
 generation and atrophy of the gland, and other observers, of 
 whom I will only mention Lancereaux as the last, have made 
 similar statements. 
 
 We must admit that the pancreas has certain connections with 
 diabetes. Some regard the disease of the pancreas as the cause, 
 some as the result. This connection is supported by the re- 
 lation between the pancreas and the coeliac plexus, especially 
 by an observation of Klebs respecting atrophy of the pancreas, 
 associated with degeneration of a certain number of the ganglion 
 cells of the coeliac plexus. In these clinically-supported theories 
 there are, of course, many gaps, which have been supplied by 
 the above-named observers, who have found that animals surviving 
 a long time after complete extirpation of the pancreas suffered 
 in consequence of the operation from persistent glycosuria, or 
 rather from a condition quite analogous to diabetes, with polyuria, 
 polydipsia, polyphagia, progressive wasting, &c., and an excretion 
 of sugar amounting to as much as 10 per cent. These symptoms 
 did not occur if a small part of the gland, not less than one- 
 tenth of its entire weight, was left behind. These results were 
 not attributable merely to the absence of pancreatic juice from 
 the intestine, as diabetes did not occur after tying the duct, 
 but to a specific, hitherto unknown function of the pancreas 
 upon the intermediate metamorphosis of matter which under 
 normal conditions miist stand in some relation to the consumption 
 
160 LECTURES ON DIGESTIOTf. [Lect. IX. 
 
 of sugar, so that when the gland is removed sugar comes to 
 be excreted. 
 
 That these experiments are very significant in respect to the 
 relations of the pancreas to the metamorphosis of sugar needs 
 no special demonstration. The total extirpation of the pancreas 
 has been attempted by Senn and Martinotti, successfully by the 
 latter. But he has not recognised its, consequences with respect 
 to the sugar. 
 
 Pisenti observed, after tying the pancreatic duct, a diminution 
 of the excretion of indican to a third or even a fifth part of the 
 original amount. 
 
 If a febrile temperature is excited in animals with pancreatic 
 fistulse, the fermentative power of, the secretion, according to 
 Stolnikow, increases at first but is later diminished. 
 
 In diseases of the pancreas, extraordinarily rapid wasting 
 has been noticed; Here a causal connection may very well 
 exist, although Oolin's animals bore extirpation of the pancreas 
 without injury, and Schiff saw artificially induced atrophy of the 
 gland remain without visible results. Meanwhile, with respect 
 to these and all similar experiments, we may urge that they 
 extend over too short a , time, , and that chronic destruction 
 acts very ' differently, to acute softening. Genuine simple pan- 
 creatic degeneration is one of the ;-arest occurrences. There 
 nearly always are present metastases , to the organs adjacent to 
 the gland, which make the connections illusive between these 
 general diseases and the pancreas. Finally, Schiff maintains 
 that the pancreas is definitely and intimately dependent upon 
 the spleen. After extirpation or^ elimination of the latter, the 
 secretion of active pancreatic juice stops. This view, as I have 
 proved, originates in a complete mistake. Dogs, whose spleens 
 have, been extirpated, secrete as before a perfectly efficient 
 secretion. My statements have been confirmed by Heidenhain 
 and Bufalioi. 
 
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 11 
 
162 LECTURES ON DIGESTION. [Lect. IX. 
 
 Le Nobel. Bin Fall von Fettstuhlgang mit gleichseitiger CHyoosurie. Deutsohes 
 
 Arch. f. klin. Med. xiii., 1888, p. 288. 
 V. Meiing and MinkowsM. Diabetes mellitus nach Fancreaseztirpation. Arch. 
 
 f. eip. Path, xxvi., 1889. 
 Senn. The Surgery of the Pancreas as based upon experiments and clinical 
 
 researches, Amer. Jonm. Med. Sciences, Jnly, 1886. 
 Hartinotti. SnUa extirpazione del Pancreas. Giom. Acad. Med. Torino, xxxvi., 
 
 1888, No. 7. 
 Fisenti. Sol rapporti fra I'azione dal succo pancreatico sulle substance album. 
 
 e la quantita d. Indicano. Arch. Med. Ital. xii,,|No. 5. 
 Lanc^reaux. Nouveaux f aits du 'diabfete sucrd aveo alteration du pancr^is. 
 
 BuU de I'Aoad. No. 19, 1888. 
 Abelmann. XTeber die Ausnutzung der Kahruugstoffe naoh Pankreasextirpatlon. 
 
 Inaug.-DisB. Dorpat, 1890. 
 
163 
 
 LECTURE X. 
 
 Gentlemen, — With the pancreatic digestion the digestive 
 function of the alimentary canal reaches its highest point. What 
 happens in the long course through the small and large intestine 
 is chiefly directed to the absorption of altered nutriment and the 
 elimination of unused refuse. Numerous glands, it is true, exist 
 in the wall of the intestine, the latest and completest descrip- 
 tion of which we owe to Schwalbe, but it is not ascertained what 
 and how great a part Brunner's and Lieberkiihn's glands, the 
 solitary follicles and Peyer's patches, play in the digestive pro- 
 cesses. It is in the nature of things that we cannot investigate 
 the particular secretion of each gland, but only a mixture of them, 
 in the form of the intestinal juice or an infusion of more or less 
 carefully isolated Brunner's glands. I shall give you only a few 
 hipts concerning the histological structure of these organs. 
 
 Brunner's glands are tubular, much convoluted glands lying in 
 the submucous tissue, and most numerous near the pylorus. 
 They possess membraneless cells with granular contents and 
 elliptical nuclei imbedded in a homogeneous basis substance. In 
 respect to their membrana propria, ducts, blood and lymph 
 vessels, they bear such a close resemblance to the acinous glands, 
 that we may regard them as a mixed type between the tubular and 
 acinous glands, but still, as was first pointed out by Schwalbe 
 and confirmed by Griitzner, they possess the greatest resemblance 
 to the pyloric glands in the stomach. During digestion the cells 
 are small and cloudy, during fasting large and clear, so that the 
 same peculiar change dependent upon the fanctions of the cell 
 occurs in them which we have so repeatedly met with. According 
 to Griitzner the large clear cells are full of pepsin, while the small 
 and cloudy cells contain little. 
 
 Lieberkiihn's glands are also tubular, with membraneless cells 
 having granular contents and a homogeneous basis substance, 
 inclosed in a membrana propria of connective tissue. According 
 to Schwalbe, they differ from Brunner's glands concerning the 
 
164 LECTURES ON DIGESTION. Lect. X. 
 
 course of the tubes and the shape of their cells in some minute 
 details. In these, the proper secreting cells pass up from the 
 fundus close to the lumen of the gland, where their free bases 
 have often quite the appearance of a so-called basal seam set with 
 rodlets, just like the epithelium of the intestinal villi which we 
 shall have to consider later under the processes of absorption. 
 They are distinguished, however, from the last-named elements, as 
 Heidenhain has recently shown, by the presence of numerous 
 figures formed by nuclear division, the so-called mitoses. 
 
 Heidenhain finds that Lieberkiihn's glands, even to a greater 
 extent in the large intestine than in the small, are infiltrated with 
 typical mucous cells, which disappear when the intestinal mucous 
 membrane is strongly irritated (as by intra-venous injection of 
 pilocarpin, which is always followed by copious thin secretions), 
 and in their stead are found cells resembling in appearance the 
 ordinary gland cells. But here we seem to have to do with only 
 an emptying of the mucus collected in the cells, and not with 
 their destruction and new formation (vide supra, the salivary 
 glands). Moreover, so far as concerns the glands in the large 
 intestine, Klug and Koreck dispute altogether their glandular 
 character, on the ground that they secrete no digestive juice 
 whatever, and declare that they are only invaginations of the 
 mucous membrane designed to increase the absorbing surface in 
 the same way as the villi do in the small intestine. " With fluid 
 intestinal contents, villi projecting into the intestine are in fact 
 the most favourable organs for absorption ; but the more solid 
 contents of the large intestine would compress such villi against 
 the wall of the intestine and eventually damage them, so that 
 here the simpler invaginations are better able to increase the 
 absorbing surface and to further absorption of such nutritive 
 material as is not absorbed in the small intestine." 
 
 This view is difiicult to confirm or refute, at least I do not find 
 that the more recent works on this subject go into it, and even 
 Bizzozero, who has lately been much engaged in the study of the 
 tubular glands of the intestine, has added no new facts to this 
 question. 
 
 On the other hand, we know definitely that the solitary glands 
 and Peyer's patches are not a secreting but an absorbing appara- 
 tus, which has many analogies with the follicles of the tonsils, 
 the thymus, or the malpighian bodies of the spleen. These 
 
THE INTESTINAL INNERVATION. 165 
 
 glands are spherical, lying close under the mucous surface, and 
 have a capsule of connective tissue in which numerous round 
 cells and nuclei are imbedded in a generally turbid fluid 
 coagulable by acetic acid, but surrounded by a capillary network 
 sending branches into the follicle. They are, as you know, most 
 abundantly found in the neighbourhood of the ileo-c»cal valve. 
 
 Brunner's glands lie so close together in the upper part of the 
 small intestine, that we may regard an infusion of this portion 
 as an extract of them, without fear of its containing much foreign 
 admixture. Such an extract, prepared, according to Griitzner, 
 with glycerine or 0"1 per cent, solution of hydrochloric acid, 
 dissolves fibrin readily, and, according to Budge and Krolow, has 
 also a diastatic action, hence the former investigator disputes 
 the complete analogy between Brunner's glands and the pyloric 
 gastric glands. I have prepared only one such extract, acting 
 completely like that of Griitzner. 
 
 Our knowledge of the innervation of the intestine may be 
 summarised in the following fashion. 
 
 In the wall of the intestine there are, as is well known, two 
 great collections of ganglionic matter which are distributed, one 
 in the submucosa, the other between the circular and longitudinal 
 layers of the muscular coat. They are distinguished by the 
 names of Meissner's and Auerbach's plexuses. Drasch was able 
 to follow up fibres springing from Meissner's plexus to Brunner's 
 and Lieberkiihn's glands and into the villi, where they are in part 
 distributed like a tree, in part interlaced like a basket; but as to 
 the connection of the nerves with the glands, in their physiologi- 
 cal relations, we know very little more than can be learned from 
 an experiment of Moreau's. He placed four ligatures at equal 
 distances upon a piece of intestine, cut all the nerves which went 
 to the middle of these three compartments, and replaced the 
 whole in the abdominal cavity ; after a certain, time he found the 
 upper and lower loops empty as before, but the middle loop was 
 filled with much fluid — 100 grms. in three hours — containing 
 albumen and inorganic salts. This experiment hardly touches 
 the question of the innervation of the glands; it is much more 
 important -for the question of diarrhoea. M. Moreau neglected 
 to perform any experiment on the digestive properties of the 
 excreted fluid, although it was quite easy to do so ; it is therefore 
 doubtful whether it was simply a transudation from the blood 
 
166 LECTURES ON DIGESTION. [Lect. X. 
 
 resulting from paralysis of the vessels, or a secretion of the 
 intestinal glands. I do not know that his experiments have 
 been repeated by others for this purpose. 
 
 This is the place to introduce some account of the movements 
 of the intestine in their dependence upon the nervous system; 
 An easily accounted-for uncertainty reigns over this region, the 
 elucidation of which would be of great and practical interest. 
 The study of the intestinal movements in their normal relations 
 is rendered difficult by the deep invasion of the body required 
 in experiments upon them. We do not know for certain how to 
 decide what part of the phenomena observed may be due to the 
 lesion, as the result of accidental but unavoidable injuries. It is 
 now known that every local irritation of an exposed piece of 
 intestine has for its usual consequence a short local wave of con- 
 traction or peristaltic movement, which has been explained, when 
 ganglionic plexuses are present in the walls (Auerbach's plexus 
 mesentericus), as a reflex irritation coming from the ganglion cells. 
 The activity of these plexuses can give rise to spontaneous intes- 
 tinal movements. But it is not quite clearly shown where we can 
 produce local contractions. We must either assume the presence 
 of ganglia, as we have done above with reference to Goltz's 
 experiment on the gastric innervation, or, like Bngelmann, take 
 refuge in another hypothesis, namely, that the movement of 
 muscle cells originates in themselves. By means of a peculiar 
 observation Nothnagel believes that he has refuted the latter viewi 
 If a small crystal of a soda or potash salt is placed upon the 
 exposed intestine, the sodium salt causes a contraction running 
 some centimetres upwards towards the stomach, while the potash 
 salt causes only a quite limited local constriction. But if the 
 nervous apparatus of the intestine is killed in any way, for 
 example, by bleeding or tying the vessels of a loop of intestine, 
 or by poisoning it with morphine, the longitudinal contraction 
 after the application of sodium no longer occurs, and only the 
 local reaction follows. A proof, as Nothnagel thinks, that nervous 
 elements must participate in the former case. But the broader, 
 longer waves are obviously to be ascribed to general causes 
 lying outside the organ. They can be attributed either directly 
 to the terminal nervous apparatus in the intestine, or indirectly 
 to changes in its circulation. It was formerly believed that the 
 movements of the intestine were caused by vascular anaemia, by 
 
THE INTESTINAL MOVEMENTS. 167 
 
 obstruction of the aorta (ScMff), or by general changes in the 
 circulation in the intestinal vessels (Bonders), while hyperEemia 
 checked the movements (Betz). But this is not altogether 
 correct. Pfliiger showed by his famous discovery of the inhibi- 
 tory power of the splanchnics on the intestinal movements, that; 
 on the contrary, vascular anaemia may be combined with 
 inhibition, and hypersemia with excitation of peristalsis. Mayer 
 and Basch saw compression of the aorta followed by quieter 
 movement or by stasis of the movements of the intestine. But 
 the constancy of the splanchnic influence cannot be altogether 
 confirmed. It is the same with stimulation of the vagus 
 or artificial hindrance to the respiration, two factors which 
 should equally have peristalsis as a constant result. All these 
 give irregular results, sometimes positive, sometimes negative, 
 sometimes none at all. Pal has quite recently proved by careful 
 researches on this point that opening the abdomen alone checks 
 the movement of the intestine. On the other hand, Braam 
 Houckgeest has endeavoured to get rid of the irritating influx 
 ence of the atmospheric air in the examination of the exposed 
 intestine, by opening and observing the abdominal cavity of 
 animals under water (^ per cent, solution of common salt). He 
 confirms Pfliiger's statements concerning the splanchnic. 
 Paralysis {i.e., section) of this nerve, which, as you know, is 
 accompanied by hypersemia of the intestinal vessels, is followed 
 by increased peristalsis, that is, increased activity of the motor 
 elements of the small intestine; while stimulation of the 
 splanchnic, which causes vascular contraction and anemia, is 
 followed by inhibition of the movements. The vagus, however, 
 influences peristalsis only indirectly, by causing contraction of 
 the stomach, and thereby gives an impulse to the intestinal 
 movements, whilst peristaltic waves may be induced in any part 
 of the intestine without the intervention of the vagus. Accord- 
 ing to experiments published by Ehrmann from Prof, von Basch's 
 laboratory, the splanchnic and vagus exercise a double and indeed 
 crossed action on the longitudinal and circular muscular fibres, 
 which may be explained by the following diagram : — 
 
 Longitudinal fibres moved by x / controlled by the 
 
 the splanchnic \ / vagus 
 
 Circular fibres moved by ihe /\ controlled by the 
 
 vagus splanchnic 
 
168 LECTURES ON DIGESTION. [Lbct. X. 
 
 The motor and inhibitory nerves of the rectum have similar 
 relations, as was proved in the same laboratory by Fellner. But 
 in this case the longitudinal and circular muscular fibres are 
 innervated separately. "The motor nerves for the longitudinal 
 muscles run in a branch of the sacral plexus, anastomosing with 
 the hypogastric plexus, and known as the 'nervus erigens'; 
 and the motor fibres for the circular muscles lie in a pair of 
 nerves which start from the posterior mesenteric ganglion and 
 send branches to the hypogastric plexus." The motor nerves, 
 therefore, exert an inhibiting influence in a crossed fashion. 
 The motor nerves of the longitudinal fibres inhibit the circular 
 fibres, and conversely, so that the motor impulse to one set of 
 muscles has an antagonistic efiect on the other. There is good 
 reason for this. If both sets of muscular fibres were to contract 
 at the same time, the lumen of the intestine would be, as one 
 can easily perceive, completely, or nearly completely closed, it 
 would give rise to a stationary contraction of the bowel, and 
 not to progressive waves such as are understood by peristalsis. 
 The latter, moreover, consists much more in combined con- 
 traction and relaxation of both sets of muscles, so that one 
 set of fibres comes into action only when the other is at rest. 
 The inhibiting centre for the movements of the bowel, which 
 may be studied after the administration of morphine or opium, 
 according to the experiments of Pal and Bergriin, is situated 
 in the neighbourhood of the lower cervical and upper thoracic 
 cord. Finally, the circulation is so far important that the "pour- 
 ing out of digestive juices " in any part of the intestine causes 
 spontaneous movements, while anaemia of the intestine always 
 stops or at least enfeebles them. Fubbini and Luzzati have 
 observed in animals with Vella's fistalae (vide infra), that the 
 movements of the intestine were favoured by the flow of bile, 
 whilst they were slowed by sleep and by low temperatures. 
 A more intimate knowledge of these relations, especially in 
 connection with the influence of varying compositions of the blood, 
 has not yet been gained in spite of many experiments directed 
 to them (Salvioli). 
 
 But the intestinal contents, which consist of gases and solid 
 matter, may, by irritating the wall of the intestine, give rise 
 to peristalsis, and in connection with this point the conclusions 
 of Bokai are very interesting, as he repeatedly undertook the 
 
THE INTESTINAL MOVEMENTS. 169 
 
 observation of the intestines in warm salt baths, introducing 
 various gases and dissolved matter into different parts. According 
 to him nitrogen and hydrogen are indifferent, on the other hand 
 carbonic acid excites strongly, first peristaltic and then rolling 
 movements of the bowels, which can be limited or cut off by 
 oxygen. Marsh gas and sulphuretted hydrogen act in a similar 
 way, but are much less feebly influenced by oxygen, a result which 
 Bokai compares with the well-known laxative effect of sulphur, 
 and which he attributes to the formation of sulphuretted hydro- 
 gen, while on the other hand he ascribes the action of bismuth in 
 controlling diarrhoea to its property of combining with sulphu- 
 retted hydrogen. The acids present in faeces, lactic acid, acetic 
 acid, and acids of the fatty series, proved also to be strong 
 stimulants of intestinal movement, the strongest being caprylic 
 and the weakest lactic acid. Of the products of putrefaction, 
 skatol even in small quantities caused very strong peristalsis, 
 while phenol and indol proved indifferent. 
 
 Hitherto it has been generally believed that antiperistaltic 
 movements never occur in normal living animals, and as Noth- 
 nagel saw, only occur when strongly irritating substances are 
 present in the intestine. This is not correct, as Jacoby has 
 recently seen, for by the employment of better methods which 
 exclude intestinal irritation, he has observed spontaneous anti- 
 peristalsis (in cats), not only in the small intestine proper but at 
 the lower end of the ileum, which were not caused by any 
 external irritation caused by the experiment. Kirstein has 
 added another proof of the occurrence of anti-peristalsis, by 
 cutting out a piece of intestine about 57 cm. long and sewing it 
 in again the reverse way. The animals remained alive after the 
 experiments without any special affection, a dog living to seven 
 weeks, when he was killed in perfect health. It follows from 
 these experiments that antiperistalsis must have occurred in the 
 piece of intestine which was resected, or otherwise the intestinal 
 contents could not have passed through it. Still we cannot 
 speak of this as antiperistalsis in a proper pathological sense, 
 and this does not occur in a pronounced fashion in the upper end 
 of a completely tied loop of intestine. These observations are of 
 great importance in connection with ileus and faecal vomiting. 
 The ancient view formulated by van Swieten, according to which 
 pressure of the abdominal walls and not antiperistalsis drives 
 
170 LECTURES ON DIGESTION. [Lect. X. 
 
 the intestinal contents through the stomach, has acquired fresh 
 value. The method of " expression " employed by Boas and 
 myself in the diagnostic examination of the stomach, shows 
 how easily the stomach contents can be expelled by ab- 
 dominal pressure when the cardiac orifice is open. Horvath's 
 statement is of practical interest, that cold from 0° to 19° causes 
 a prolonged or complete cessation of peristalsis, a fact of which 
 I have made use for some time by injecting cold water into the 
 intestine in the treatment of the diarrhoea of children. Very 
 noteworthy, finally, for the explanation of the therapeutic 
 working of morphine (or opium) would be an observation of 
 Nothnagel's, if confirmed, from which he is led to attribute the 
 constipating effect of morphine to an excitation of the inhibitory 
 nerves of the intestine. He saw the peristalsis caused by sodium 
 salts, which has been already described, cease after relatively 
 small injections of morphia, but return when the piece of intestine 
 in question was severed from the mesentery, and thus separated 
 from its connection with the splanchnic nerve. Apart from the 
 fact that Nothnagel appears to have overlooked the double 
 (crossed) innervation of the intestine (vide supra), it is clear that 
 in this experiment there were allterations in the circulation and 
 local causes of irritation which could have participated quite as 
 much as irritation or inhibition of the nerves leading to the 
 part. 
 
 The intestinal juice is best obtained by means of Thiry-Vella's 
 fistulas. An excised piece of intestine, about 30 to 50 cm. long, 
 still left in connection with the mesentery, is sewn up at one end, 
 while the other is united to the abdominal wound. The continuity 
 of the rest of the intestine is repaired by carefully sewing the 
 ends together. The secretion of these fistulse, or, as they should 
 rather be called, pieces of intestine, is regarded as normal 
 intestinal juice, but it may be questioned how far the secretion 
 of such a piece of intestine exposed to the air exhibits normal 
 relations, and the following data, upon which there is by no 
 means a desirable amount of harmony, are to be accepted with 
 a certain degree of reserve. This uncertainty is explicable, 
 if we consider how easily after such an operation, quite apart 
 from the irritation to the mucous membrane, vascular altera- 
 tions may occur which may lead to transudations from the 
 blood, and quantitative or qualitative changes ■ in the fluid 
 
THE INTESTINAL JOICE. 171 
 
 from tlie fistula. Every one knows who has worked at the 
 intestine and mesentery how extraordinarily irritable the vessels 
 are, and the experiment of Moreau just related is so far evidence 
 of this. Besides, the fistula does not secrete spontaneously, but 
 only upon mechanical irritation or pilocarpine injection. Neither 
 direct irritation of the vagus nor reflex irritation, as by rubbing 
 the abdomen with croton oil, gives rise to secretion. Lehmann 
 found the secretion alkaline, opalescent, clear sherry-coloured, 
 sp. gr. 1017 to 1021, with 3-6 to 4<-7 solid matter, of which 
 1"53 per cent, was organic material. Thiry estimated that a dog 
 in from two to seven hours after feeding secreted in his whole 
 intestine about 350 grms. As to its action, agreement prevails 
 only on one point, namely, that it dissolves fibrin. With respect 
 to the rest, the statements diverge widely, some asserting it to 
 have a fermentative action on other albuminoids or on starch and 
 fat, while others deny these. Bunge regards the chief importance 
 of the reaction of Branner's and Lieberkiihn's glands to be its 
 alkalinity and its component carbonates, by which the excessive 
 acidity of the chyme is neutralised. An observation of Demant's 
 was made on the secretion of a fistula of the ileum, in a patient 
 whose upper intestinal contents were separated from it and 
 emptied by a second fistula ; he obtained only a diastatic and 
 inverting ferment in the intestinal juice, but found neither 
 peptonising nor fat-splitting properties in it. Gumilewski was 
 also able to note its strong diastatic properties. On the other hand, 
 Vella, in his animals operated upon (eighteen dogs) proved with 
 certainty the existence of a diastatic emulsifying and glycerine- 
 forming as well as peptonising action. In fact, the intestinal 
 juice, in spite of its alkaline reaction, possesses also the property 
 of curdling milk, as milk injected in at one opening always 
 comes out at the other curdled. You remember, gentlemen, that 
 Kiihne and Eoberts ascribe to pancreatic juice a kind of rennet 
 action on milk. But in the most recent and careful researches 
 which Hohmann has made upon three dogs with Vella's fistula, 
 of which one had a piece of intestine 30 cm. long, there is no 
 question of any milk-curdling action of the intestinal juice, but, 
 on the other hand, the diastatic action is distinct, as it does not 
 only convert starch into sugar, an action which is stronger in the 
 upper sections of the bowel than in the lower, but it converts 
 cane sugar into invert sugar. However, some one should investi^ 
 
172 LECTURES ON DIGESTION. [Lbct. X. 
 
 gate whether all living tissue in contact with the air does not possess 
 this feeble diastatic action, and also the power of coagulating 
 casein. So much is certain, that even the dried intestinal mucous 
 membrane cut into small pieces inverts cane sugar, and can 
 transform dextrine into maltose (Brown and Heron, Ewald), and 
 the majority of authors have affirmed the diastatic action of the 
 intestinal juice. But the statements are very contradictory, and 
 I will therefore not weary you with further details of the dis- 
 cussion. Boas has recently described a method for obtaining the 
 intestinal juice, or, more properly speaking, the intestinal con- 
 tents, of living human beings not operated on. It is possible in 
 many persons to press back the contents of the duodenum into 
 the stomach, and to obtain these by means of the stomach tube. 
 No doubt, according to the fulness and the irritability of the 
 stomach, these are more or less mixed with the stomach contents 
 or gastric juice, and, according to the stage of digestion, the ex- 
 pressed material must consist of a mixture of bile, pancreatic 
 juice, intestinal juice, the digested products of the stomach, and 
 that still undigested. It is clear that such a product can afiford 
 no certain conclusions as to the action of pure intestinal juice, and 
 its main interest consists in the possibility of observing how far 
 these different juices antagonise one another. We shall return 
 to this question later on. As in the large intestine either none 
 or only traces of a digestive fluid are secreted, and the absorbing 
 function of the intestine becomes almost its exclusive business, 
 we can, so soon as we have considered the constitution of the 
 intestinal contents, in so far as they are still preserved, approach 
 the most important and prominent peculiarity of the intestinal 
 mucous membrane, its absorbing function. 
 
 The chyme, the composition of which we have described at its 
 entrance into the intestine, becomes altered as it passes down the 
 intestine in its chemical and physical relations in the following 
 manner : the reaction becomes alkaline or at least neutral in the 
 jejunum, as in my case before alluded to, while it seems, 
 according to the observations of Schmidt-Mulheim, J. Munk, and 
 Cash, that in dogs it may be acid from first to last. In the ileum, 
 even in man, it becomes acid from the formation of acids from the 
 putrefaction of albumen and fermentative processes. The sub- 
 stances which we have already learnt to recognise as the products 
 of putrefaction, are in fact all, or nearly all, present in the lower 
 
INTESTINAL PUTREFACTION. 173 
 
 part of the alimentary canal, and owe their existence obviously 
 to the same putrefactive processes as produce them outside the 
 animal body, only that, favoured here by the natural conditions, 
 they proceed more actively than elsewhere, and are accompanied 
 by fermentative processes which lead to the formation of lactic 
 acid, butyric acid, &c. I have only to refer you to the formulae 
 which I showed you previously (pp. 27 and 151) for these processes, 
 for you to have at one glance the whole of these bodies before your 
 eyes. If you recall at the same time the obscure proposition of 
 the iatro-chemical school related in the introductory Lecture, 
 which made the digestion a putrefactive process, these remark- 
 able facts acquire in themselves an increased interest, and we are 
 reminded of an apt remark of Du Bois Reymond's that the curve 
 of scientific opinion always comes back after a certain time to its 
 starting-point. 
 
 Besides the products of putrefaction which belong to the so- 
 called aromatic substances, and besides the so-called ptomaines, 
 whose importance and significance we have already studied, there 
 are particularly two of these bodies which have excited in 
 recent times an overwhelming amount of attention. Indol 
 (O^NHgCH), first found by W. Kiihne in bacterial putrefaction, 
 and phenol (CeHjOH), or its homologues ortho- and paracresol, 
 which was discovered by Baumann in putrid albumen, and by 
 Brieger directly in human faeces. Both appear in the urine by 
 absorption from the intestine. Indol is oxidised to indoxyl, and 
 this combines with sulphuric acid and potash to form potassium 
 indoxyl sulphate, or indican, the mother substance of that pig- 
 ment which gives the urine a blue colour on the addition of 
 hydrochloric acid and solution of chloride of lime (calcium hypo- 
 chlorite), that is to say, the indican in the presence of oxidising 
 agents splits up into indigo blue and potassium sulphate, and the 
 test for indican in the urine is based upon this reaction. Phenol 
 or cresol combines after its absorption from the bowel with 
 sulphuric acid, and appears for the most part as phenol-sulphuric 
 acid in the urine. Both are dependent for their occurrence and 
 their quantity upon the intensity of the putrefaction going on in 
 the intestine and the rapidity of the movements of the intestinal 
 contents or their stay in the lower portion of the canal. 
 
 The quantity of phenol excreted in the urine amounts normally, 
 according to J. Munk, to 0-017 to 0-051 grms., but according to 
 
174 LECTURES ON DIGESTION. [Lect. X. 
 
 Brieger may reach as high as 0'6 grms. Normal human urine, 
 according to Jaffe, is very poor in indican (6"6 mgrms. to the 
 litre), an amount which is greatly increased only in pathological 
 conditions, occlusion of the small intestine, internal hernias, 
 carcinoma, &c., that is, processes which lead to stasis of the 
 intestinal contents and to proportionally greater decomposition. 
 But these, like all the bodies belonging to this group, have 
 scarcely anything to do with the true digestive and nutritive 
 processes. In cases like that of mine, where the lower part of the 
 ileum and the large intestine were as good as completely closed, 
 and the entire intestinal contents down to the fistula, which was 
 probably seated in the lower third of the ileum, were discharged 
 by it, these substances were completely absent, only returning 
 when the connection between the upper and lower intestine 
 was renewed by operation. Still the nutrition of the patient 
 proceeded well, and, considering the general derangement, was 
 particularly good. Indol and phenol are allied products, which 
 the body gets rid of as waste through two channels, the kidneys 
 and the intestine, whilst they own their formation, as above 
 remarked, exclusively to putrefactive processes in the contents 
 of the bowel. E. Baumann, by preventing these processes by 
 large doses of calomel, was able, in complete accordance with my 
 above related observation, to notice the complete absence of 
 aromatic substances from the urine, and Kast and Wasbutzki have 
 estimated the excretion of ether-sulphuric acid as the direct 
 measure of the putrefactive processes in the bowel, and the effect 
 produced on them by the free acids of the gastric juice. But 
 these are processes of a universal nature, and the hopes have not 
 been confirmed which were first raised by Jaffa's experiments, that 
 close connections might be formed between pathological conditions 
 of the intestine and the excretion of these bodies. Senator, 
 whom I can completely confirm from my own experience, has 
 drawn attention to the inconstancy in the amount of indican 
 excreted. These statements have since been confirmed by 
 Hennigs and Nothnagel. The same, according to Brieger, is 
 true of phenol, and when we consider how many factors participate 
 in the excretion of these substances — food, rapidity of peristalsis, 
 intensity of putrefaction, amount of absorption — we cannot be 
 surprised at this. 
 
 But if we turn away from this practical point, it is certainly 
 
THE INTESTINAL GASES. 175 
 
 very interesting that phenol, which we make use of extensively 
 every day for its antiseptic properties, should be found as a pro- 
 duct of putrefaction, and that actually in our own intestines ! 
 
 The intestinal gases, the formation of which is explained by the 
 table of fermentations, consist of carbonic acid, hydrogen, nitro- 
 gen, sulphuretted hydrogen, and marsh gas, which last is formed 
 by a special fermentation, marsh gas fermentation, the substratum 
 of which exists in the cellulose taken with vegetable food. 
 These amounts vary very much, being in part dependent upon 
 the diet — ^I may remind you of the flatulence following ingestion 
 of certainly easily fermentable vegetables, cabbages, &c. — in part 
 on the absorption of gases formed in the blood. A great part, 
 indeed the principal portion of the intestinal gases are, as 
 Professor Zuntz has proved by the interesting work of his pupil 
 Tacke, taken up at once into the blood and eliminated in the 
 expired air through the lungs. It was shown in one experiment 
 (made on rabbits) that whilst in two hours 2'1 ccm. of gas were 
 got rid of by the anus, 16'7 ccm. of hydrogen and carburetted 
 hydrogen were discharged by the lungs; and in another, whilst 
 during ten hours forty-five minutes 30 ccm. of gas were passed 
 from the rectum, the enormous quantity of 103'5 ccm. of hydrogen 
 and carburetted hydrogen was excreted by the lungs. So that 
 we must conclude that from ten to twelve times as much gas 
 passed out by the lungs as by the anus. Tappeiner has sug- 
 gested — at present not proved — that there are two kinds of 
 organisms concerned, of which one forms carbonic acid and 
 hydrogen, the other carbonic acid and marsh gas, and by the 
 (supposed) greater resistance of the former to acids, he has 
 sought to explain the larger quantity of the former gases in the 
 upper parts of the intestine and of marsh gas in the lower por- 
 tions. In excessive meteorism, such as is caused by paralysis of 
 the intestines, e.g., in typhus, we find scarcely any carbonic acid 
 and principally nitrogen ; an analysis of the gas obtained by 
 puncture in such a case gave me 8'3 per cent, of CO2, and the 
 remainder nitrogen, mixed with some oxygen derived from the 
 atmosphere, which entered during the experiment. In a woman 
 aged 54, with a stricture of the rectum, which could be kept 
 open only with the help of a bougie, and ordinarily caused faecal 
 retention and colossal meteorism, I emptied the gas collected 
 in the intestine by means of a stomach tube, and found. 
 
176 LECTURES ON DIGESTION. [Lkct. X. 
 
 seven hours after food (soup and bread), 6*9 per cent. COj, 
 11-64 per cent. H, 81'03 per cent. N. Euge found as mucli as 
 50 per cent, of marsli gas in human flatus after eating leguminous 
 vegetables. 
 
 The more the contents of the intestine pass downwards, the 
 more do they become exhausted and inspissated, and finally are 
 expelled from the bowel in formed or pulpy or even watery 
 masses, the faeces, which may be mixed under pathological con- 
 ditions with mucus, blood, or pus. For this the rapidity of 
 peristalsis is the decisive factor, the action of which, in the 
 lowest portion of the bowel, is converted from a continuous into 
 a periodic movement. The sphincters close the intestinal canal 
 like a sluice, which only from time to time opens by a sort of 
 regulating action and allows the accumulated matter to pass out. 
 At the same time we must not imagine that such matters only 
 are excreted with the faeces as are no longer useful to the organ- 
 ism. A part of the nutrient matter leaves the body under 
 ordinary circumstances in this way, frequently only slightly 
 changed. This is the surplus of the food which man, "the 
 gluttonous animal," has taken in addition to his needs, and 
 which passes too rapidly through the digestive track to undergo 
 the action of its secretions. The amount of this is naturally 
 dependent upon individual conditions. In the stools of nursing 
 infants, according to Wegscheider, we find coagulated milk, fat, 
 peptones, and even an active diastatic ferment. In adults there 
 are unaltered or only little changed remains of food. In addition 
 there are mucus, epithelium, horny substances, pigments, fatty 
 acids, and products of putrefaction of albumen. Special interest 
 is excited by a substance isolated by Brieger, scatol, a final pro- 
 duct of the putrefaction of albumen, which obviously causes the 
 odour of faeces. As abnormal components may be named round 
 (pus) cells, mucus in large quantities, blood corpuscles, and para- 
 sites or their eggs. 
 
 It is known that defaecation is subject, under normal conditions, 
 to moderate variations in frequency and character. There are 
 people who have two stools daily, others who have one every two 
 or three days, and there have been cases recorded in which the 
 bowels were opened regularly only once in eight or even four- 
 teen days, the general health being quite good. Bristowe gives 
 the maximum at from six to eight weeks. But the actions of 
 
THE FjECES. 177 
 
 drugs can defer the termination still longer; thus Williams 
 records the case of a lady who, in consequence of the habitual 
 use of opium, had very frequently only one stool in six weeks, 
 and once during a whole year had her bowels opened only four 
 times. The reverse of this is found in the numerous stools of 
 diarrhoea ; indeed in dysentery they may reach thirty or forty in 
 twenty-four hours. Their characters depend upon the secretion 
 of the intestinal mucous membrane, the transudation from the 
 blood, peristalsis and the particular kind of pathological process 
 affecting the intestinal mucous membrane, and last, not least, 
 the special contents of the intestine represented by the ingesta. 
 Sometimes one, sometimes the other of these factors prepon- 
 derates, and so it happens that the stools undergo great variations, 
 not only in relation to their composition, but to their diagnostic 
 value and pathological significance. Take, for example, the pro- 
 ducts of an ordinary summer diarrhoea and that occurring in 
 albuminuria or consumption, which, regarded apart from the 
 history, our knowledge does not in any way enable us to distin- 
 guish, yet which, in their pathological significance, are very 
 widely distinct. A number of such instances might be given. 
 
 It is remarkable how few chemical analyses of diarrhceic stools 
 we possess, if we except cholera and perhaps dysentery. The 
 former is chiefly known from Schmidt's analysis, which I give 
 here, and I place beside it the analysis of a stool produced by 
 infusion of senna : 
 
 Cholera. Senna. 
 
 Water 984-15 969-75 
 
 Albumen 1"64 
 
 Organic matter . . . 5-15 20-03 
 
 Inorganic .... 8-19 8-58 
 
 If we desire to examine diarrhceic stools in practice, it is 
 absolutely necessary not to confine ourselves to simple inspection, 
 but to leiave the stool to deposit its sediment in a tall glass. 
 The odour may be reduced to a minimum in both solid and fluid 
 stools, if, as I recommend, a thin layer of ether be poured over 
 it. After settling, we can perceive at a glance the approximate 
 quantities of water and blood, the amount of mucus and solids, 
 the colour of the sediment, and the supernatant fluid; we can 
 recognise far better the quantity and the size of certain fibrinous 
 
 12 
 
178 LECTURES ON DIGESTION. [Leot. X. 
 
 exudations whicli, as you know, are found in so-called diar- 
 rhcea tubularis, forming complete casts of the intestinal tube, 
 and, finally, can easily select portions for microscopical examina- 
 tion. The contents — in pus and blood corpuscles, in abraded 
 epithelium, mucus and elements of tumours — permit a conclusion, 
 although only approximatively, as to the intensity and nature of 
 the process going on in the intestine. The method is now greatly 
 extended, especially in all cases where there is choleraic diarrhoea, 
 in which the employment of bacterioscopic methods has become 
 indispensable. If you desire to learn more of these things, which 
 I cannot enter into here, may I recommend you, gentlemen, the 
 magnificent monograph of Nothnagel, " Beitrage zur Physiologie 
 und Pathologie des Darms," as well as the work of Bienenstock, 
 " Ueber die Bacterien der Faces," and the handbooks of 
 bacteriology. 
 
 Sohwalbe. Beitrage zur Kenntuiss der Driisen in den Dannwandiingen, 1ns- 
 
 besondere der Brunner'sohen Drileen. M. Sohultze's Arohiv. Bd. viii. p. 92. 
 Griltzner. Notizen iiber einige ungeformte Fermente des Sangethier-Organismns. 
 
 Pfliiger's Arohiv. Bd. vii. p. 285. 
 Krolow. Berliner klin. Wochensolirft. 1870, No. 1. 
 Morean. Ueber die Polgen der Durohsohneidung der Darmnerven. Cntrlbltt. 
 
 f. d. Med. Wisschft. 1868, No. 14. 
 Wegscheider. Ueber die normale Verdauung bei Sauglingen. Berlin, 1875. 
 Brieger. Ueber die flUohtige Bestandtheile der menseWieben Excremente. 
 
 Journal f . pract. Chemie. Eeprint. 1877 ; and Bericht. d. Berlin chem. Gesell- 
 
 schaft, 1877, p. 1027. 
 Bristowe. Obstrnotion of the Bowels. Eeynold's System of Medicine, Vol. iii. 
 
 p. 67. Williams' case is given here. 
 Schmidt. Characteristik der epidemischen Cholera gegeniiber verwandten 
 
 Transndationsanomalien. Leipzig u. Mittau, 1850. 
 Thiry. Ueber eine Methode den Dunndarm zu isoliren. Wiener Sitzgsber. 1864. 
 
 Bd. 1. p. 77. 
 JafB^. Ueber den Nachweis nnd die quantitative Bestimmung des Indlcans im 
 
 Ham. Pfliiger's Archiv. Bd. iii. p. 448. 
 
 Ueber die Ausscheidung des Indicans tinter physiolog. u. patholog. Ver- 
 
 haltnissen. Virohow's Archiv. Bd. Ixx. 
 Nencki. Ueber der Zersetzung der Gelatine und des Eiweisses bei der Faulniss 
 
 im Pancreas. Festschrift. Bern. 1876. 
 Banmann. Ueber die BUdung von Phenol bei der Faulniss von Eiweisskorpem. 
 
 Berichte der Berl. ohem. Gesellschft. 1877, p. 685. 
 Baumann. Ueber gepaarte Sohwefelsauren im Organismns. Pfliiger's Archiv. 
 
 Bd. xiii. p. 285. 
 
 Senator. Ueber Indioan und Kalk-Ausscheidung in Krankheiten. Cntrlbltt. f. 
 d. med. Wissenschft. 1877, No. 20, 21. 
 
BIBLIOGEiPHY. 179 
 
 Bilge. BeitrHge zur Kenntniss der Darmgase. Wiener. Sitzgsber. math-naturw. 
 
 Classe. Bd. Ixiv. p. 740. 
 Zweifel. Untersuclimigen iiber das Meconium. Archiv. f. Gynttoologie. Bd. vii. 
 
 Heft. 3. 
 Demant. Ueber die Wirkung des menschlichen Darmsaftes. Virohow's Archiv. 
 
 Bd. kxvii. p. 419. 
 S. Mayer u. Basch. TTnterauchiingen iiber Darmbewegungen. Pfliiger's Arehiv. 
 
 Bd. ii. p. 391. 
 V. Braam-Honckgeest. Untersuohnngen iiber Periataltik des Magens und Darm- 
 
 canals. Pfliiger's Archiv. Bd. vi. p. 266, and Bd. viii. p. 163. 
 Drosch. Beitrage zur feineren Kenntniss des Diinndarms. Wiener Sitzungs- 
 
 berieht. Bd. 82, p. 168. 
 Klug and Koreok. Ueber die Aufgaben der Lieberkilhn'schen Driisen im Diok- 
 
 darm. Du Boia' Archiv. 1883, Heft. 6, p. 463. 
 Ehrmann. Ueber die Innervation des Diinndarms. Wiener med. Jahrb. 1885, 
 
 Heft 1. 
 Salvioli. Eine neue Methode fur die Untersuchungen des Diinndarms. Du 
 
 Bois' Arch. Separat-abdr. 1880, p. 95. 
 Pellner. Zur Innervation des Reotums. Wiener med. Jahrb. 
 Nothnagel. BeitrSge zur Physiologic und Pathologic des Darms. Berlin, 1884. 
 Vella. Ein neues Terfahren zur Gewinnung reinen Darmsaftes und zur Fest- 
 
 etellnng seiner physiologischen Eigenschaften. Moleschott's Untersuchungen, 
 
 Bd. siii. 
 Lehmann. Eine Thiry-Vella'sohe Darmfistel an der Ziege. Pfliiger's Archiv. 
 
 Bd. xxmi. p. 88. 
 Prick. Ueber die verdauende Bigensohaft des Daimaaftes der Hauasaugethiere. 
 
 Arch. f. Thierheilknnde, 1883, p. 148. 
 Taoke. Ueber die Bedeutnng der brennbaren Gase im thierisohen Organismua. 
 
 Inaug. -Dissert. Berlin, 1884. 
 Zuutz. Die Ursachen des Meteorismus. Deutsche med. Wooh. 1884, No. 44. 
 Tappeiner. ' Vergleichende Untersuchungen der Darmgase. Zeitsoh. f. phyaiol. 
 
 Chemie. Bd. vi. p. 303. 
 Bienenstock. Ueber die Baoterien der Facea. Fortaohritte der Medicin. 
 Jacoby. Pharmakolog. Untersuchungen uber daa Colchicumgift. Arch. f. exper. 
 
 Path. Bd. xxvii. p. 144, 1889. 
 Bokai. Experlmentelle Beitrage zur Kenntniss der Darmbewegungen. Ibid. 
 
 Bd. xxiii. p. 209. 
 Pal. Einfluss des Bauchsohnitts auf die Darmbewegungen. Strieker's Arbeiten 
 
 Wien, 1890. 
 Pal and Berggriin. Ibid. 
 J. Boas. Ueber Diinndarmverdauung beim Mensohen und ihre Beziehung zur 
 
 Magenverdanung. Zeitschr. f. klin. Med. Bd. xvii. Heft. 1 and 2. 
 Kirstein. Experimentelles zur Pathologie dea Ileus. Deutsche med. Wooh. 
 
 1889, No. 49. 
 Kast. Ueber die quantitative Bemessung den antiseptischen Leistung des 
 
 Magensaftes. Festschrift zur Eroffnnng des allgemeinen Krankenhans zu 
 
 Hamburg-Eppendorf. 
 Wasbutzki. Ueber den Einfluss von Magengahningen auf die Faulnissvorgange 
 
 im Darmkanal. Arch, f . exper. Pathol. Bd. xxvi. p. 133. 
 
180 
 
 LECTURE XI. 
 
 Gentlemen, — We have to consider to-day Absorption, that is, 
 the processes by which the contents of the intestine pass into the 
 blood and chyle. There was a time, and that not so long ago, 
 when it was believed absorption occurred only by the lacteals. 
 But it is not so. Even the primse vias take part in the transference 
 of soluble matter into the vessels, and even in the cavity of the 
 mouth very readily absorbed matter is taken up. But this only 
 is true of very small quantities, dififering more or less in nature, 
 but not of the absorption of larger quantities of such substances 
 which it is the object of digestion to serve. This begins 
 in the stomach. According to the experiments of Smith and 
 Anrep, when the stomach was cut off at the pylorus, or separated 
 from the intestine by a plug introduced through a fistulous 
 opening in the duodenum, it was ascertained that sugar and pep- 
 tone were absorbed in no small amount. In the same experiments 
 it seemed probable that to some extent fat was split up in the 
 stomach, and therefore might be absorbed. However, the 
 greater part of absorbable matter is taken up from the intestine. 
 As we have said, it was at one time believed that this took place 
 only by means of the lacteals, but we know now that the 
 radicles of the portal vein participate in the process. In 
 the blood of the portal vein, between the intestine and the 
 liver, we find sugar, a dextrine-like body, and peptone, which 
 have passed direct from the intestine into the veins, so that 
 we must admit that the blood and chyle vessels share in 
 absorption, although apparently the latter perform the chief 
 part, especially that of taking up fat. In connection with 
 this interesting point, let us first see what is the structure of 
 the apparatus of this absorption, which is the function of the villi. 
 The epithelial covering of the villi presents, according to the 
 most recent researches of Heidenhain, which we shall follow here, 
 three different forms of cell: 1. Absorbing epithelial cells; 
 2. Goblet cells ; and 3. Wandering cells. Chief interest 
 
STRUCTURE OF THE VILLI. 181 
 
 attaches to the first of these. These present a cylindrical, conical, 
 or pyramidal epithelium, which is so arranged that the broad end 
 of each cell is turned towards the lumen of the intestine, and the 
 apex towards the body of the villus, being separa,ted from the 
 proper parenchyma of the villus by a membranous limiting layer 
 pierced by round or oval fenestras (Drasch, Watney). According 
 to Heidenhain, they possess no membrana propria. During 
 digestion we can see in them numerous oil globules ; indeed, 
 Moleschott and M&rfels maintain that they have seen in them (in 
 the frog) choroidal pigment and blood corpuscles from other 
 animals which were introduced into the intestine. The remark- 
 able and exceptional character of this epithelium is the so-called 
 " cover " (deckel), which is a small strip closing the cell opposite 
 the lumen of the intestine marked with fine longitudinal striae, 
 which, when looked at from above, have the appearance of 
 numerous dots. This striation does not extend quite to the 
 lower border, but ends a little higher, so that the "cover" 
 has the appearance of a comb turned with its teeth upwards. 
 This striated or rod-like appearance is presented by the so- 
 called " cover " under all physiological conditions, during fasting 
 as well as during absorption, and, indeed, whether these striae 
 are pre-formed, or are post-mortem products of splitting 
 of the cell contents — whether they represent a system of fine 
 pores or canals which, to a certain degree, permit entrance to 
 the proper cell cavity, or whether they are only an illusion 
 produced by a kind of cilia possessed by these special cells 
 are points upon which hitherto no agreement has been reached. 
 The last view is defended with great determination by 
 Thanhoffer. According to him, we have to do with moving 
 protoplasmic cell processes, which by their motion draw in 
 the smallest molecular particles, especially fat globules. Ac- 
 cording to Heidenhain, the cover consists of a homogeneous 
 white mass, into which the rodlets extend, like processes of the 
 protoplasm of the cell. They are not rigid cuticular formations, 
 but plastic processes of the cell body, as, in the event of any very 
 active changes in the form of the epithelial cells, they can be 
 thrust forward to very varying extents. In the middle of the 
 villus, lying between the vein and artery, runs the lacteal, which 
 passes into the submucous tissue, and then takes on the 
 characters of a valved vein. The capillary area of the blood- 
 
182 LECTURES ON DIGESTION. [Lect. XI. 
 
 vessels is distributed over tlie periphery of the body of the villus, 
 close beneath the epithelial layer. Between the lacteal and 
 the epithelium lies the proper parenchyma of the villus in the 
 shape of a mesh work of connective tissue, in the spaces of which, 
 besides a few wandering lymphoid cells, lie fixed cells of a 
 different kind. Heidenhain years ago stated that the central 
 lacteal is connected with the epithelium through a system of 
 connective tissue-like cells, whose processes communicate directly 
 with the open apices of the cells. Eimer and Tarschanofi" have 
 confirmed this view, which is all the more acceptable as many of 
 the facts of digestion require us to believe in the existence of 
 direct pre-formed channels for carrying the intestinal contents 
 through the epithelium of the villi into the lacteal. There can 
 be no doubt that we find fat which has come from the intestinal 
 contents in the cells of the villi during digestion, and, as is well 
 known, it can be demonstrated with ease in the contents of the 
 lacteals, so that in some way or other it must find its way out of 
 the former into the latter. But the recent careful investigations of 
 Heidenhain, which, unlike the earlier ones, have not been made 
 on the frog but on higher mammals, and with improved methods, 
 lead to the conclusion that the above-described immediate con- 
 nection between the connective tissue cells and the epithelium of 
 the villus does not exist. The epithelial cells end, for the most part, 
 at the surface of the cell without sending any processes to connect 
 them with deeper lying structures, and the fat moves into 
 the special parenchyma of the villus through pericellular spaces. 
 Tbe same would hold good for soluble food and salts in the 
 intestinal contents as they flow over the villi. 
 
 Finally, the villi are provided with a specially-arranged 
 muscular layer, divided into longitudinal and circular fibres. 
 Whilst the former, that is, the longitudinal fibres, have been long 
 known, it was Briicke who drew attention to the existence of the 
 smooth, circular fibres. The arrangement of these muscles has 
 been carefully studied by Mall, Graf Spee, and Heidenhain, who 
 have demonstrated that the longitudinal fibres form a sort of 
 buttress upon which the connective tissue framework in part 
 rests, while arch- or pencil-shaped radiating fibres are given off 
 from the muscles connecting the apices of the cells with their sides. 
 It is clear that by the contraction of this system of longitudinal 
 and transverse fibres (1) the contents of the villus are pumped up 
 
MECHANISM OF ABSORPTION. 183 
 
 to the tuft of the lacteal, and (2) new material from the intestine 
 is sucked up into the villus, whilst in the intervals of contraction 
 the central canal, by the assistance of the valves already referred 
 to, works in a manner analogous to that of the heart. 
 
 As is well known, the intestinal villi are regarded as an 
 " artifice of nature " to multiply the already by no means small 
 surface of the intestinal canal. Heidenhain found that in a 
 square centimetre of dog's intestine there are 2,500 villi ; Mall 
 gives a smaller number, namely, 1,600. Taking the first-named 
 number and the measurements of von Spee, and reckoning on 
 the supposition that the average length of a villus is 1'48 mm., 
 the breadth 0'2 mm., the entire absorbing surface of a villus 
 cylinder is 0'969 mm. ; therefore a square centimetre of intes- 
 tinal mucous membrane would, if the villi could be stretched out, 
 cover a surface of not less than 23 square centimetres, so that the 
 absorbing surface is increased more than twenty times. 
 
 Let us see in what manner the intestinal contents pass through 
 the villi into the lymph circulation of the intestinal mucous 
 membrane, that is, the absorption of the intestinal contents. 
 
 The special process of absorption appears at the first blush as 
 the proposition that the contents of the blood-vessels and lacteals 
 and those of the intestine represent two fluids separated by a 
 membrane, the wall of the villus, behaving as if in a dialyser, 
 an explanation which at first sight offers no great difficulty. It 
 is generally admitted that the exchange between the intestinal 
 contents and the blood follows the laws of diffusion and endos- 
 mosis. This may be at once granted in so far as concerns 
 inorganic salts, but not for other substances. The passage of 
 water into the blood would be brought about by the previously 
 mentioned high endosmotic equivalent of the albumen found in 
 the blood, which favours a current of water out of the intestine 
 into the richly albuminous blood; the absorption of peptone 
 takes place in consequence of the great difierence in the endos- 
 motic equivalent between it and raw albumen, at least according 
 to physical laws, and the like takes place for solutions of sugar. 
 These views find experimental support in the experiments which 
 have been made, partly by Funke, partly by Becker and others, 
 and which show that solutions of common salt, sugar, and peptone, 
 injected into ligatured loops of intestine, disappear from the loop 
 in more or less time in proportion to their concentration. But it 
 
184 LECTDRES ON DIGESTION. [Lect. XI. 
 
 is plain tKafc such experiments can teach us only the fact of 
 -absorption and the practical conditions respecting it, not the 
 details of the processes themselves. It has been shown that the 
 presumed higher diffusive capacity of peptone is actually very 
 slight (Adamkiewicz, Maly), and cannot at all explain the 
 phenomena of absorption. Nevertheless it is true, and has been 
 proved by comparative experiments, that peptone leaves the 
 intestine and passes into the circulation more rapidly than 
 unchanged .albumen, and that with it and the salts large 
 quantities of water are taken up from the intestine. Heidenhain 
 injected water coloured with methyl-blue into a ligatured loop of 
 intestine, then killed the animal, and examined the wall of the 
 bowel microscopically. By this means he convinced himself that 
 the absorbed water passed through as well as between the cells. 
 In further experiments he measured the quantity of water present 
 in the contents of a loop of intestine, and also the quantity of 
 chyle absorbed therefrom in a given time ; the difference between 
 these two factors gave the quantity of water taken up by 
 the blood-vessels, and showed that they take up by far the 
 greatest quantity of the water absorbed. This accords with an 
 earlier observation of Zawilsky, namely, that the quantity of 
 lymph is not much greater during digestion than while fasting. 
 But all these are, I might say, only secondary facts, and the 
 forces which effect the transfer of water and albumen, or albu- 
 moses and peptones, into the lacteals and blood-vessels are by 
 no means explained, whether one describes them as " vital 
 processes," or labels them as a series of unknown chemical and 
 physical processes. We stand in face of just such an unexplained 
 fact as we encountered in connection with the absorption of fat, 
 though one may say that, contrary to earlier views, the ab- 
 sorption of fat has become more intelligible to us, while the 
 absorption of albumen presents more difficulties than ever. 
 Fat does not diffuse at all, or at least not in a manner extensive 
 enough for the purposes of absorption. Nevertheless we find 
 after a fatty meal free fat in the chyle and blood, and it may 
 be seen in its resting-place in the epithelium of the villi, 
 on its way from the intestine to the blood. There are here 
 many possibilities. Either the fat in substance enters the 
 lacteal through the membrane of the villus, for which there 
 must be some provision to make the process mechanically 
 
ABSORPTION OF FAT. 185 
 
 possible ; or the fat is decomposed chemically and split up into 
 diffusible and absorbable [Components, which then at some place 
 — not to be accurately defined — unite again to form fat; or, 
 finally, the fat is taken up by some easily moving elements 
 (wandering cells), and transported by them through the paren- 
 chyma of the villus into the lacteal, where it is again set free. 
 For all these possibilities there is some kind of evidence, but 
 the question cannot be decided in one direction or the other. 
 Respecting the mechanical absorption of fat, we may at present 
 speak as follows : a fundamental condition for the absorption of 
 fat in substance is obviously its division so finely that single 
 droplets can pass through the epithelium or the pores of its covers. 
 For this purpose the fat must be emulsified, that is, the fat 
 must be divided, either by mechanical or physical force, in the 
 presence of a more or less viscid menstruum, into small spherules, 
 which, according to the goodness of the emulsion, remain apart 
 for a longer or shorter time, then coalesce to form large drops, 
 and finally to become a compact layer of fluid fat. But such fine 
 emulsions, as was formerly believed, are to be obtained outside 
 the organism only by the employment of strong mechanical 
 forces, which cannot by any means be attained by the muscula- 
 ture of the intestine, and we were always in a dilemma how to 
 explain the formation of the emulsion obviously present. You 
 see now the significance of Gad's proof of the self-emulsification 
 of fat, which we have already spoken of in detail, especially as 
 this investigator has made it probable that the fine fat-drops of 
 the emulsion described do not surpass the diameter of an epi- 
 thelial pore; The emulsification of fat in the intestine takes 
 place partly in this way, partly through the pancreatic juice and 
 the animal gums contained in the intestinal mucus. The latter 
 — the animal gums — possess, according to Landwehr, great fat- 
 emulsifying properties, and are separated from the intestinal 
 mucus through the action of the bile. We may place alongside 
 this statement, which has not yet been confirmed, the self-emulsi- 
 fication of fats, as Gad describes it, which is easily demonstrated 
 at any time by a certain and easily performed experiment ; and 
 the very important question as to the force by which fat is sub- 
 divided in the intestine finds a satisfactory answer, in the smallest 
 and least apparent forces, which here, as so often in Nature, 
 produce mighty results, if its effect or at least its role as one 
 
186 LECTURES ON DIGESTION. [Lect. XI. 
 
 of the factors in the absorption of fat had not been established 
 by a number of independent observations. It is easy to demon- 
 strate that after eating fat the intestinal villi are covered 
 with a cream-like layer, which consists of microscopic fat 
 droplets, but these fat spherules are not far removed in their 
 minuteness from the powder-like division of fat met with in 
 chyle. There is. however, wanting the soap or free alkali 
 ordinarily necessary for the formation of such an emulsion. 
 Schmidt-Mulheim, J. Munk, and Cash have found the reaction of 
 the intestinal contents of a dog after feeding with fat to be acid 
 throughout; while Munk and Cash found no emulsion, only 
 fat in large drops, in the intestinal contents of an animal fed 
 with fat; and, finally, v. Frey showed that the chyle-formed 
 emulsion differs from other emulsions, in so far that the 
 latter disappear on acidulation, but the former is stable, while, 
 on the other hand, for the formation of an emulsion by 
 shaking, as that of the chyle is formed, no soap is necessary. 
 The acid reaction of the intestine is not, for many reasons, 
 so important as at first sight it appears to be. I may remind 
 you of the experiments of v. Lindenberg, already described, 
 which established the remarkable fact of the activity of 
 trypsin in lactic and acetic acid menstrua, and I may ask 
 whether a good emulsion may not be formed by pancreatic 
 juice even in acid intestinal contents, when this reaction is caused 
 by small quantities of free lactic acid or acid salts. In the second 
 place, my case of duodenal fistula shows that the intestinal con- 
 tents after fatty food have at least a neutral and not an acid 
 reaction, and I would suggest the question whether the acid 
 reaction may not be a consequence of the splitting up of a 
 certain amount of fat, and whether free fat is still found 
 merely because there is too much to be dealt with all at 
 once. Finally, CI. Bernard has shown that pancreatic emul- 
 sions differ from other emulsions by occurring in acid solutions. 
 So that the possibility of the formation of emulsions on a large 
 scale for the purpose of absorption is by no means excluded, 
 and is much better founded than the opinion that fluid fat 
 is absorbed without any previous emulsification. The experi- 
 ment of von Wistinghausen affords a basis for the latter view, 
 according to which bile or its acids exercises an influence 
 over the rising of oil in capillary tubes, and, consequently, in the 
 
ABSOBPTION OF FAT. 187 
 
 capillary pores of animal membranes. The experiment is as 
 follows : — 
 
 Two almost capillary glass tubes, of wtich one is washed 
 inside with a solution of bile acid, and the other with a solution 
 of soda or with water, are dipped side by side into a glass of oil. 
 The oil rises in both by capillary attraction for some distance, 
 but reaches about a millimetre higher in the tube containing bile 
 acid than in the other. 
 
 Further, bile acid favours the passage of fat through damp 
 animal membranes; and as the epithelium of the villi in the 
 intestine is bathed in bile, this circumstance, in connection 
 with the facts discovered by Wistinghausen, greatly eluci- 
 dates, if it does not solve, the question of the passage of fat 
 through the pores of the epithelium into the commencement of 
 the lacteal. Still, Groper has recently made some observations 
 which call in question Wistinghausen's experiments. He studied 
 the relations of various fluids to the absorption of fats in 
 capillary spaces, and proved in the capillaries of blotting paper, 
 wool fibres deprived of their grease, and animal membranes, that 
 soaking these substances with bile or water made no difference 
 to their permeability for oil. But such assistance would only be 
 needed if the fat globules were too large to pass through the 
 pores without resistance ; otherwise they would be suspended in 
 the stream of fluid which runs from the intestine to the lacteal, 
 and they would be subject to the same laws of motion as this. 
 Meanwhile the striation of the basal border, formerly taken to 
 be due to pores in the epithelium, is, according to more recent 
 statements, much more probably caused by ciliated processes, 
 a pre-formed canal system being therefore absent. Finally, 
 J. Munk and F. Miiller have shown in almost corresponding 
 researches that even fat, the melting temperature of which 
 is above the body temperature, for example, spermaceti, 
 which first melts at 53° C, is absorbed freely. Here purely 
 physical processes such as are concerned in Wistinghausen's 
 experiment cannot be in question. Nevertheless it is certain 
 that the bile, as we have already seen, plays an important part 
 in the absorption of fat, only, unfortunately, we must place after 
 the how ? a very large note of interrogation. 
 
 Zawarykin and Schafer have lately made statements which at 
 first sight appear very fascinating. It is known with what 
 
188 LECTURES ON DIGESTION. pjECT. XI. 
 
 eagerness tlie lymph-corpuscles take up foreign bodies and 
 transport them by means of amaeboid movements from place to 
 place. Such elements on the surface of the epithelium of a 
 villus become charged with fat droplets, or almost corpuscular fat, 
 which they carry through the epithelium into the lymph spaces 
 of the villus, where they may be met with in all stages of 
 their progress, and by treatment with osmic acid black fat 
 droplets may be demonstrated in them. Here we have the 
 ants which labour at the carriage of non-emulsified or un- 
 decomposed fat, and furnish us with a happy solution of a 
 much-laboured controversy, which even the obvious objection, 
 that the cells always carry fat and never other corpuscular 
 elements (pigments, &c.), cannot damage. We may explain 
 this by supposing that they possess a certain selective power. 
 But the facts do not support the hypothesis. Wiemer has 
 undertaken a careful inquiry into this question, and concludes 
 that though a small amount of fat may be found enclosed in 
 lymph-corpuscles between the epithelial cells and between these 
 and the central lymph space, the greater part is free, and must 
 have found its way in a free state into the epithelium. This 
 view is substantially that taken by Bysoldt as the result of 
 studies published from the Physiological Institute of Kiel on the 
 absoi-ption of fat ; and Heidenhain says in his most recent and 
 much-quoted work, after having given many reasons and adduced 
 the circumstance that black granules in cells after treatment by 
 osmic acid do not necessarily prove the presence of fat, that "it is 
 scarcely possible to think that the leucocytes play an important 
 part in the transport of fat." It is not to be doubted, according 
 to this investigator, that fat, even in large drops, is found within 
 the epithelium, and that it moves within the pericellular spaces 
 of the parenchyma of the villi, whence the greater part of it 
 passes into the central lacteal, whilst any absorption by the 
 capillaries of the villus, if it does take place at all, is at most 
 doubtful. 
 
 But are we then thrown back upon the passage of fat in 
 substance in order to explain the milk-white appearance of the 
 chyle after fatty food ? By no means. Indeed we have learnt 
 many other factors which show us that the mechanical absorption 
 of fat, if it occurs at all, is only small in amount. 01. Bernard 
 sought for an explanation of this absorption in the property of 
 
ABSOKPTION OF FAT. 189 
 
 pancreatic juice discovered by him, by which it splits neutral fats 
 into glycerine and the corresponding fatty acids. It is true that 
 this was found only in an executed criminal. As is well known 
 the blood contains soluble soaps, that is, combinations of fatty 
 acids with soda or potash, and it appears very plausible to admit 
 that these are formed in the intestine by the alkalies introduced 
 with the food out of the decomposed fat, and absorbed according 
 to the laws of diffusion. Thus it is very well explained how soaps 
 are formed in the intestine and gain entrance to the blood, but 
 not how fat as such gets from the intestine into the vessels. 
 Younger investigators have, therefore, gone a step further, and 
 have sought to prove that both the components of fat, the glycerine 
 and the fatty acids, make their way separately from the cavity of 
 the intestine into the villi, and are first reconverted by synthesis 
 to form fat, either in the epithelial cells themselves, or at least 
 on their way to the thoracic duct, in which by some a previous 
 saponification of the fatty acids is accepted. This standpoint is 
 taken by Will and Perewoznikoif, who hold that the regeneration 
 takes place in the epithelium of the villi. Will fed animals with 
 palmitic acid and glycerine, as well as with pure soap made from 
 palmitic acid and glycerine, and found in both cases a marked 
 fatty infiltration of the intestinal epithelium, in which after 
 treatment with osmic acid the fat droplets were stained deep 
 black, a test against which, however, we have seen Heidenhain 
 protests. J. Munk proved by exact experiments, quite recently 
 confirmed by Walther in Ludwig's laboratory, that the balance of 
 tissue metamorphosis in a dog remains the same, whether he is 
 fed with fat or a corresponding amount of fatty acids ; but he 
 found that fatty acids, like fluid fats, are emulsified in feeble 
 alkaline media, and considered that, given a certain richness of 
 fatty food, the available alkali is not suflBcient to saponify the 
 resulting fatty acids, and that these are taken up in the form of 
 an emulsion. On the way to the thoracic duct this emulsion 
 must in great part be reconverted into fat, as the chyle of such 
 animals is milk-white (as in feeding with fat), and chemical 
 analysis shows that it contains besides the fatty acids a consider- 
 able, and indeed absolutely large amount of neutral fat. He 
 found about 88 times as much as in the thoracic duct of a 
 starving dog, and 20 times as much as in the thoracic duct of a 
 dog fed on meat, whence he was able to conclude that not only 
 
190 LECTURES ON DIGESTION. [Lect. XI. 
 
 fatty acids belonging to such fat as is normally present in the 
 bodies of dogs, but also quite diiSferent kinds of fat, such as pigs' 
 fat or mutton suet, could be in this way utilised in large 
 quantities in the animal body. Synthesis of the absorbed fatty 
 acids so as to form neutral fats, and their utilisation in the 
 organism, is not to be doubted, but it is very doubtful if we can 
 look upon this as the only or even the chief condition of fat, as 
 P. Walther in repeating and continuing the experiments of 
 Munk found that when fatty acids were introduced into the 
 intestine a part of them were converted even in the cavity of the 
 small intestine into glycerides, that is, neutral fats, the very 
 opposite condition to that which is desired, according to Munk's 
 views, for the absorption of fat. So that we are not much nearer 
 a final settlement of this question, as none of these experiments 
 make the particular process of fat absorption intelligible. We 
 must accept a compromise between the chemical and mechanical 
 theories. There is a chemical decomposition of fat, then a 
 mechanical carriage of the resulting emulsion of fatty acids, and 
 finally a chemical regeneration (synthesis) of this emulsion 
 with the postulated glycerine to form fat. No recent attempt 
 has been made to solve this puzzle ! 
 
 As to the place where the necessary synthesis occurs, we may 
 venture — as they appear to be confirmed by results — to give 
 the conclusions of my experiments, according to which the so- 
 called surviving intestinal mucous membrane, that is, the mucous 
 membrane of a recently killed dog carefully separated from the 
 muscular and serous coats, possesses the power of forming fat 
 from soap and glycerine. Unfortunately I have not been able of 
 late years to continue these experiments and to make the proof 
 complete. 
 
 From all this, gentlemen, you see that we have only an un- 
 certain and shifting basis for our knowledge of this important 
 process, and that there is much yet to be done upon it. But are 
 the physical laws as at present known sufficient to explain the 
 transference of the entire intestinal contents from the cavity of 
 the intestine to the vessels, even if we admit that the whole of the 
 matter to be transferred is physically transferable, i.e., dilfusible ? 
 This cannot by any means be affirmed without reserve. Voit 
 and Bauer have drawn attention to many facts which do not agree 
 with simple diffusion or endosmosis. Only we should not need 
 
MECHANISM OF ABSORPTION. 191 
 
 to fall back upon endosmosis and diffusion if we accept, with 
 Briicke, a periodical contraction of the musculature of the villi, 
 as before mentioned, a sort of pump action in the villi, which, 
 mutatis mutandis, works like the heart ; or if we accept the view 
 that the mechanical force of peristalsis drives the contents of 
 the intestine into the blood and chyle vessels by a sort of 
 filtration under pressure. But a pump ought to work regularly, 
 and, without distinguishing between fluids of different composition, 
 it should make the contents of the well (the intestine) come 
 through the pipe (the cells and first lymph spaces) into the 
 trough (the lacteal). But in the present case it is not so. We 
 know that different substances in solution in the intestine do 
 not pass into the chyle, and we have had this demonstrated by 
 Tappeiner's experiments upon the variations in the absorption of 
 bile acids in different portions of the intestine. The observations 
 of Lannois and Lepine also prove that the entire upper portion 
 of the small intestine absorbs better than the lower, but under 
 certain conditions — obviously when the epithelium is irritated — 
 this becomes equalised. Moreover, leucin and tyrosin have 
 never been found in the repeatedly examined portal blood or 
 chyle, although these bodies are formed by the pancreatic 
 digestion, and the former at least is quite soluble in water. 
 Simple pumping certainly does not take place, but the stimulated 
 muscular action serves only as a means of motion for the stream 
 once set in motion in the lacteals ; and we may remember that 
 the valves of the lacteals, beginning in the submucous coat, must 
 promote this by preventing reflux. But this theory does not 
 explain the passage through the epithelium. The following 
 suggestions of Hoppe-Seyler find their place here: 1, fat can 
 pass undissolved into the chyle through the intestinal epithelium 
 independently of the villi (in the lower animals) ; and 2, the 
 absorption of water from the intestine into the blood is dependent 
 upon healthy living epithelial cells, and simple irritation of these 
 cells suffices to turn the stream from the blood and lymph into 
 the intestine. Finally, Hoppe-Seyler adds, that a series of toxic 
 substances, phosphorus, arsenic, preparations of antimony and 
 jalap, abolish or diminish absorption by killing or irritating the 
 cylindrical epithelium. The first and last of these points seem 
 to me to be most important. The transudation of water into the 
 intestine originates not in the irritation of the epitbelium, but in 
 
192 LECTURES ON DIGESTION. LLect. XI. 
 
 the vaso-motor nerves. We can completely kill the epithelium 
 of a mucous membrane with nitrate of silver without causing a 
 trace of redema, which, however, occurs at once when substances 
 which act more deeply are employed, and quite the same takes 
 place on the external skin. In the second case also, the normal 
 absorption from the intestine would be surpassed by the transuda- 
 tion out of the vessels, and therefore no conclusion would, be 
 possible from this condition as to a special function of the 
 epithelium. But the above points are less easily rejected by the 
 adherents of the physical theory of absorption. 
 
 Ludwig has drawn attention, through his pupil Zawilsky, to the 
 fact that the quantity of fat present in the chyle is independent 
 of the amount of water ; whilst the view of a general filtration 
 through the epithelium (whether endosmotic or mechanical by 
 means of the muscles of the villi) would make a direct relation 
 between fat and water very probable. If we were to ascribe the 
 absorption to the laws of diffusion alone, when a dilute-solution 
 of alcohol is injected into the intestine, water should pass out of 
 the blood into the intestine, while just the reverse occurs. Thus 
 Brieger found by experiments which he performed according 
 to the method of Moreau (p. 165), that 0'5 — 1 per cent, 
 solutions of neutral salts were followed by no transudation into 
 the ligatured intestinal loops, but 20 per cent, solutions pro- 
 duced a clear yellow alkaline fluid, containing shreds of mucus, 
 epithelium, and mucous granules, so that irritation of the mucous 
 membrane was a necessary stimulus to the process, which we were 
 always accustomed to regard as simply due to the high endosmotic 
 equivalent of the neutral salts. The objections thus multiply 
 against the view that absorption is a purely physical phenomenon, 
 and Hoppe-Seyler's description, although provisionally only an 
 hypothesis, must receive the greatest consideration, "that 
 absorption takes place mainly through chemical affinities, 
 conditioned by the life of the cell, which is thereby itself changed 
 and used up." 
 
 Gentlemen, the foregoing words were written by me five 
 years ago, and I have only to add to them, that though the views 
 stated have made way scarcely one investigator has devoted 
 himself to the exclusively physical theory of absorption. Ap- 
 parently they compound the forces of absorption out of three 
 factors, chemical, physical, and mechanical. Though Heidenhain 
 
THE SEAT OF ABSORPTION. 193 
 
 has calculated that the movement of fluid in intestinal absorption 
 is very slow, so that for example it takes five minutes to pass 
 through the epithelial layer — Lehmann found on injecting iodide 
 of potassium into a loop of intestine that the first traces were 
 found in the blood of the mesenteric vein five minutes after — 
 yet the force which impels the fluid along the lacteals must be 
 a powerful one. If the thoracic duct is tied (Schmidt-Mulheim), 
 or occluded by new growths, the mesenteric lymphatics are filled 
 to bursting, and there is expansion of the perivascular spaces 
 in the neighbourhood of the mesenteric lymphatic glands, the 
 pancreas, &c. 
 
 Where does absorption take place, and what is absorbed ? 
 The first is as easy as the second is difficult to answer. That the 
 entire intestinal tract, from the stomach to the sphincter ani, 
 participates in absorption in different degrees in different parts, 
 has been placed beyond doubt by numerous observations and 
 investigations. We have already spoken of the absorption of 
 sugar from the stomach, and have only, parenthetically, to add 
 that the absorbing capacity of the gastric mucous membrane for 
 substances which pass easily into the blood, as, for example, 
 iodide of potassium, has recently been used for diagnostic 
 purposes. Penzoldt found the period of absorption to vary in 
 health between 6-| and 15 minutes (proved by giving iodide of 
 potassium in gelatine paper capsules, and testing the saliva at 
 short intervals with starch paper), whilst in chronic gastric 
 catarrh and dilatation this is greatly increased, so that the 
 reaction does not occur for half an hour or more (Wolff, Paber, 
 Quetsch, Zweifel, Haberlin). But even on fat the gastric mucous 
 membrane is not entirely without influence. At least Ogata 
 found, in Ludwig's laboratory, that neutral fats were decomposed 
 in the stomach to fatty acids, and Cash observed, during the 
 digestion of freshly minced gastric mucous membrane, fat and a 
 little hydrochloric acid, a direct formation of fatty acids. Klem- 
 perer and Scheurlen performed experiments on men by introducing 
 pure oleic acid or chemically pure olein into the stomach, and 
 after an interval withdrawing the stomach contents for investiga- 
 tion. They found that though 1 — 2 per cent, of the neutral fat 
 was decomposed in the stomach — partly by the action of certain 
 bacteria, but chiefly attributable to a physiological action of the 
 gastric mucous membrane — yet no absorption of neutral fat or 
 
 13 
 
194 LECTURES ON DIGESTION. [Lect. XI. 
 
 free fatty acids occurs in the stomach. Hoiyever, this does not 
 agree with certain experiments which I have made hy introducing 
 a mixture of oil and starch paste into the stomach. I found after 
 a certain variable but never constant lapse of time, that the pro- 
 portions between the quantities of oil and starch paste present 
 had undergone a change, which would not be the case were it 
 simply a question of their passage into the duodenum. So 
 that I am obliged, in order to explain this recurrence, to 
 admit that there is a certain absorption of fat by the wall of the 
 stomach. 
 
 On the other hand there can be no doubt of the absorption of 
 peptone from the stomach, which appears to keep pace with its 
 production, as Schmidt-Mulheim has found that the proportions 
 between peptone and albumen in the expressed contents of the 
 stomach remain the same throughout all stages of digestion. 
 We are also justified in regarding the stomach as the place in 
 which the process of absorption of nutriment into the vessels 
 first begins, as we must also maintain that it reaches its maximum 
 in the small intestine and diminishes again lower down. Even 
 the large intestine, however, possesses, according to Voit and 
 Bauer, a certain capacity for absorbing fat (of 1 2 grms. of goose 
 fat injected, 2-2 grms. disappeared). Special interest attaches 
 from a practical point of view to the question of absorption from 
 the large intestine, which, thanks to Leube, plays in recent times 
 a beneficent part in therapeutics by the; use of nutrient enemata 
 based thereupon. Leube has shown, as you know, that compounds 
 of minced meat, fat, pancreas, and water, injected per anum into 
 an animal in a state of nitrogenous equilibrium, can maintain it 
 in this condition for some time without any food being given it 
 by the mouth, and he has applied this in practice with the 
 happiest results. This combination is intended to peptonise the 
 meat by means of the pancreas. Its preparation is a little 
 particular, as the product often irritates the bowel, especially 
 after long use, and is quickly expelled. We have now available 
 much better preparations in the various manufactured prepara- 
 tions of peptone-albumose — Leube's solution, Kemmerich's meat 
 peptone, Adamkiewicz or Sanders-Ezn's peptone, Antweiler's al- 
 bumoses. It is certainly impossible that a healthy person, much 
 less a sick person, can be nourished for any length of time by 
 the rectum, although each part of the intestinal tract can act 
 
NUTRIENT ENEMATA. 195 
 
 vicariously at times for others, because all tHe principal factors 
 are, so to speak, in duplicate ; yet the co-operation of all the 
 factors is needed for the scantiest nutrition : without it no 
 extensive absorption is possible. Voit and Bauer in their best 
 case could only effect the absorption from the rectum of about 
 a fourth part of the albumen necessary to life, with the addition 
 of fat or hydrocarbons. The great value of nutritive enemata 
 is not so much in prolonging the lives of patients with incurable 
 strictures, carcinoma, &c., which make feeding impossible by 
 the mouth, as by permitting complete rest in acute affec- 
 tions of the upper part of the digestive tract ; and in this 
 sense their employment is, to my mind, still much too little 
 generalised amongst the profession. Finally, I must not omit 
 that Savory maintains that there is a more rapid absorption 
 of drugs from the intestine than from the stomach. The action 
 of those administered by the mouth is weakened, partly from 
 changes which the substances undergo from the gastric juice, 
 partly from their dilution in the chyme. 
 
 The next question, what is absorbed ? points chiefly to the 
 bodies arising from normal digestion, as we have learnt to 
 recognise them, and the products of the complicating processes. 
 Thus peptone, sugar, probably dextrine-like bodies, salts, water, 
 gelatine, glycocoll, fat, and soaps, perhaps also leucin, are directly 
 taken up, as is proved by the presence of these substances in the 
 blood and tissues. So, too, with some of the bodies ascribed 
 to the putrefaction of albumen, indol and phenol, which we find 
 again, although in an altered form, in the urine as indican and 
 phenyl-sulphuric acid. On the other hand, we know no positive 
 facts which permit the view that undigested albumen on the 
 one hand, or the remains of putrefactive products on the other, 
 as well as a series of organic acids — acetic, butyric, capronic, 
 valerianic acids — partly introduced with the food, partly formed 
 by fermentation of the hydrocarbons, do pass into the blood, 
 or let us know the magnitude of this passage if it actually 
 occurs. We are just as little informed as to how far the gases, 
 carbonic acid, hydrogen, marsh gas, sulphuretted hydrogen, and 
 ammonia, which are developed in these processes, find their way 
 into the blood. But by what channels do the absorbed materials 
 travel ? Are they exclusively the lymph (chyle) vessels, or do 
 the radicles of the portal vein participate, and to what extent ? 
 
196 LECTURES ON DIGESTION. [Lect. XI. 
 
 These questions, old as the discovery of the lymphatic system by 
 Avelli, Rudbeck, and Pacquet, were first decided by Magendie 
 in the sense that absorption takes place in both ways. An 
 animal dies after the introduction of a soluble poison into its 
 intestine, although the thoracic duct is tied. A glance at the 
 white distended lacteals of an animal during the digestion of 
 fat, proves that fat exclusively or mainly goes this way. 
 Respecting sugar, v. Mering has proved that it passes into 
 the blood, and no demonstrable amount can be found in the 
 chyle. The same fact is known respecting . many salts ; for 
 example, sulphindigotate of soda, while others, such as sodium 
 chloride, are distinguished by the fact that they are not taken 
 up in proportion to their concentration, but that the relation 
 between water and salt absorbed differs, as Gumilewski has 
 shown, according to the concentration of the solution, so that 
 in weak solutions (0'25 per cent. NaCl) more water is absorbed 
 than salt to correspond, while in stronger solutions (from 
 1 per cent.) more salt than water. Moreover, we know that 
 albumen and blood are constituents of the portal blood as of 
 the chyle. But very remarkably we find after the richest albu- 
 minous meal only traces of peptone in the blood; indeed, 
 Neumann found that even when great quantities of peptone 
 were present in the intestine, only the slightest traces were 
 to be found in the blood or the lymph ; and, even when peptone 
 is injected into the- blood, it can only be demonstrated in traces 
 for a few minutes. Nevertheless, the blood has always much 
 albumen, about 8 per cent., and if peptone is digested with 
 blood, outside the organism, it remains unchanged, wherefore 
 it follows that the blood contains no substances which can 
 destroy peptone. The peptones must, when taken up, be 
 very rapidly reconverted into albumen, or it may be that 
 albumen as such is absorbed. 
 
 The question whether unchanged albumen coagulable by heat 
 passes into the blood and becomes used up in nutrition, is some- 
 times affirmed, sometimes denied. Bernard and Pavy have 
 proved that dissolved albumen, casein and globulin, injected 
 into the blood, reappear in the urine, and pass unchanged 
 through the organism. It is known that after heavy meals 
 a slight amount of albumen is occasionally present in the urine, 
 a circumstance which appears to speak in favour of the passage 
 
THE EECONVERSION OF PEPTONE INTO ALBUMEN. 197 
 
 of unchanged albumen into tlie blood. In fact, possibly a small 
 part of undigested albumen may pass directly into the blood ; 
 but by far the greatest quantity of the albumen which forms 
 our tissues and circulates in our blood, originates undoubtedly 
 from peptone changed back again into albumen, which is eifected, 
 as shown already, by simple anhydration, a process which we 
 find so often in the organism. The possibility of this is fully 
 proved by the experiments of Maly, Plosz, Adamkiewicz, and 
 others, which agree in showing that feeding with pure peptone is 
 sufficient for animal nutrition. We cannot see anything in the 
 entire process of peptonisation, or in the transformation of 
 sugar into starch, but a chemical contrivance which the organism 
 employs in order to transport large masses of material in the 
 shortest possible time and in the purest possible form. When 
 this is effected, the animal body has at its command another 
 means, anhydration, or the removal of water, to again con- 
 solidate the matter in question into its original form or one 
 of its allied forms, and to store it up for use. Whether this 
 occurs, as Hofmeister believes, through the agency of the colour- 
 less cells of the adenoid tissue, or in some other fashion, must 
 remain for the present an open question. Heidenhain holds, 
 in opposition to Hofmeister's view, that the quantity of absorb- 
 able (dried) albuminates, which can pass into the circulation 
 within twenty-four hours, is much greater than the total weight 
 of the fresh mucous membrane, which contains, besides blood 
 corpuscles, glands, blood-vessels, epithelium, and connective 
 tissue, and that, according to his calculation, 80 grms. of fresh 
 lymph corpuscles, possessing only 20 grms. of dry material 
 amongst them, must assimilate 274 grms. of dried albumen, 
 which would require an enormous power of subdivision on the 
 part of the leucocyte, which microscopic examination of them 
 does not suggest. Briicke, the most determined representative 
 of the view that unchanged albumen is absorbed, has found 
 ordinary unchanged albumen in the lacteals, and moreover 
 shows that a completely dissolved digestive mixture of pepsin, 
 albumen, and hydrochloric acid, after neutralisation and removal 
 of the precipitated syntonin, gives, on heating, a precipitate of 
 coagulable albumen; and he argues, that if such solutions are 
 absorbed, the coagulable albumen contained in them must be 
 absorbed too. The first observation, made by such a careful 
 
198 LECTUEES ON DIGESTION. [Lect. XI. 
 
 observer, is, unless we iiave to do with some anomalous condition, 
 of great weight. But the presence of coagulable albumen in 
 apparently digested digestive mixtures, on which Briicke lays 
 great stress, is due, as I have repeatedly proved, simply to 
 incomplete digestion. If the digestion in such a solution be 
 started anew by the addition of some fresh pepsin and hydro- 
 chloric acid, after a short time there is no longer any albumen 
 present coagulable by heat. So much appears to be certain, 
 by analogy with many other processes, that all digestive actions 
 proceed more quickly inside the organism, and their products 
 occur earlier, than we can imitate with our retorts and incubators. 
 But, on the other side, the experiments of Eichhorst and myself 
 have shown that unchanged albumen injected into the rectum 
 is absorbed, and can maintain the nitrogenous equilibrium, 
 although no peptonising function is possessed by the lower 
 portions of the bowel ; and the quite unexpected and paradoxical 
 discoveries of v. Ott, Nadina Popoff, and J. Brinck, have shown 
 that peptone or albumen solutions introduced into the stomach 
 or intestine give rise to the formation of serum-albumen in the 
 cavity of the organ. The obvious objection that they had to 
 do with an exudation of blood serum from the wall of the cavity 
 and not with a reconversion of peptone into serum-albumen, 
 is not discussed in the works in question, but appears to be 
 excluded, as this peculiarity occurred only with stomach peptone 
 but not with pancreas peptone. 
 
 Naunyn, loo. cit., has found a dextrine-like body in the blood of the portal vein. 
 Thanhoffer. Beitriige znr Fettresorbtion und hlatologischen Struotur der Diinn- 
 
 darmzotten. Pfluger's Arohiv. Bd. viii. p. 391. 
 Eortunatow. Ueber die Fettresorbtion und histologisohen Strncttir der Dilnn- 
 
 darmzotten. Pfluger's Arohiv. Bd. xiv. p. 285. 
 Funke. Ueber das endosmotisehe Terhalten der Peptone. Tirohow's Arohiv. 
 
 Bd. xiii. p. 449. 
 Beoher. Ueber das Verhalten des Zuokers beim thierisohen StofEweohsel. 
 
 Ztsohrft. f. Wissensohftl. Zoologie, Bd. v. p. 123. 
 Zawilsky. Dauer und Umfang des Fettatromes duroh den Brustgang nach 
 
 Fettgenuss. Arbeiten aus d. physiol. Anstalt. a. Leipzig, 1876. 
 Brieger. Znr physiologisohen Wirkung der Abfuhrmittel. Ctrlbltt. f. d. med. 
 
 Wissensohft. 1878, p. 365. 
 Leube. Krankheiten des Magens und Darms. Ziemssen's Hdboh. Bd. vii. 
 
 2Halfte. Ueber die Therapie der Magenkrankheiten. Volkmann'a Sammlung, 
 
 No. 62. Ueber die Ernahrung der Kranken vom Mastdarm aus. Deutsoh. 
 
 Arohiv. f . klin. Med. Bd. i. p. 1. 
 
BIBLIOGRAPHY. 199 
 
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 Du Bois' Arch. Supplement, 1883, p. 302. 
 PerewoznikofE. Zur Frage von der Synthese des Pettes. Oentralbl. 1874, p. 851. 
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 Hofmeister. Versuche Uber Resorption und Assimilation der Nahrstoffs. Arch. 
 
 f. exper. Path. Bd. xix. and xxii. 
 TTeber Verbreitung der Peptone im Thierkorper. Zeitschr. f. 
 
 physiol. Chemie, Bd. v. p. 129, Bd. vi. p. 51. Ueber die Ruckbildung von 
 
 Eiweiss ans Pepton. Zeitschr. f. physiol. Chemie, Bd. ii. p. 206. 
 Sohmidt-MUhlheim. Das Eiweiss auf seiner Wanderung durch den Thierkorper. 
 
 Biolog. Centralbl. 1881, p. 312. 
 Maly. Die Entstellungen und Verwirrungen in der Peptonlehre. PflUger's 
 
 Arch. Bd. xx. 
 H. Eiohhorst. Ueber die Resorption der Albuminate im Diokdarm. PflUger's 
 
 Arch. Bd. iv. 1871. 
 C. A. Ewald. Ueber die Ernahrung mit Pepton- und Eierklystieren. Zeitschr. 
 
 f . klin. Med. Bd. xii. Heft 5 and 6. 
 N. Drosdorff. Ueber die Resorption der Peptone, des Eohrzuckers, und der 
 
 Indigoschwef elsiiure vom Darmcanal aus und ihr Nachweis im Blut der V. port. 
 
 Zeitschr. f. physiol. Chemie, Bd. i. 1887, p. 216. 
 
200 LECTURES ON DIGESTION. [Lect. XI. 
 
 E. Neumeiater. Ueber die Einfiihrung der Albnmosen tmdJPeptone in den 
 
 Organismns. Zeitsohr. f. Biologie, N. F. Bd. ^n. 1888, p. 272. 
 L. Vella. Neues Verfahren zur Gewinnung reinen Darmsaftes imd znr Feat- 
 
 stellung seiner phyaiologisohen Bigenachaften. Molesohott'a TJnterauolinngen, 
 
 Bd. xiii. 1881. 
 V. Ott. Ueber die Bildung von Serumalbumin im Magen, &o. Du Bois' Arch. 
 
 1883, p. 1, 
 Nadina Popoff . Ueber die Bildnng von Serumalbumin im Darmoanal. Zeitachr. 
 
 f. Biologie, N. F. Bd. vii. p. 427. 
 Jnlia Brinck. Ueber Syntbetische Wirkung lebender Zellen. Ibid. p. 453. 
 E. Heidenhain, Beitrage znr Hiatologie und Physiologie der Dilnndarmsobleim- 
 
 baut. Pfluger's Arch. Bd. xliii. Supplement, 1888. 
 MaU. Ueber die Blut- und Lymphwege im Dunndarm dea Hundea. Leipziger 
 
 Sitzungaberiohte, Bd. xiv. 
 Basoh. Die eraten Chyluawege und die Pettreaorption. Wiener Sitzungaberiohte, 
 
 Bd. lii. 1870. 
 P. Paneth. Ueber die Seoernirenden Zellen des Diinndarmaepitliela. Arch. f. 
 
 mik. Anatomie, Bd. xxxi. 1888. 
 Graf Spee. Beobaobtungen tiber den Bewegungsapparat und die Bewegungen 
 
 der Darmzotten, aowie deren Bedeutnng filr den Chyluasirom. Arch. f. Auat. 
 
 und Entwiokelungsgesehichte, t. His and Braune, 1885. 
 Zawarykin. Ueber die Pettreaorption im Dunndarm. Pfluger's Arch. Bd. xxxi. 
 
 1883, Bd. xxxT. 1884, Bd. xl. 1887. 
 Wiedersheim. Ueber die meobaniache Aufnahme der Nahrungamittel in die 
 
 Darmaohleimhaut. Preiburger Festschrift zur 56, Naturforscherveraammlung, 
 . 1887. 
 Eohmann. Ueber Secretion und Eesorption im Dunndarm. Pfliiger'a Arch. 
 
 Bd. xli. p. 411. 
 Eysoldt. Ein Beitrag zur Frage der Fettresorption. Inaug.-Dissert. Kiel. 
 Klemperer and Soheurlen. Daa Verhalten dea Fettea im |Magen. Zeitachr. f . 
 
 klin. Med. Bd. xv. Heft 4. 
 Graenhagen. Ueber Fettresorption im Darm. Pfliiger'a Arcb. Bd. xUv. p. 535. 
 
201 
 
 LECTURE XII. 
 
 Gentlemen, — The intestinal tract forms, from tlie beginning 
 to the end, a continuous canal into which, the various gland 
 ducts open like tributaries, their specific secretions being not 
 isolated, but mingled complexly in it. There obviously exist also 
 certain reflex connections between the various organs. Richet, 
 in his patient with gastric fistula and stricture of the oesophagus, 
 saw that when food was introduced by a tube into the stomach 
 the salivary secretion was increased, and on chewing sapid 
 and odorous substances a proportionally strong flow of gastric 
 juice occurred. Moreover, according to the investigations of 
 Hiifner, Munk, and Kiihne, the various secreting organs possess 
 not only the main specific properties described in the previous 
 chapters, such as the action of ptyalin in the saliva, and that of 
 pepsin in the gastric juice, but it may be easily proved that the 
 actions of one gland approach in some degree to those of the 
 others. Thus J. Munk found that saliva treated with hydrochloric 
 acid digested fibrin and formed peptone ; and, on the other hand, 
 that a diastatic ferment could be separated by glycerine from the 
 stomach and intestinal mucous membrane. Kiihne records the 
 same, but he also proves that trypsin is found only in the pan- 
 creas or its secretion. The experiments of Ogata, according to 
 which the stomach splits up neutral fats into glycerine and fatty 
 acids, have been related in the previous lecture. These are, how- 
 ever, accidental or at most concomitant phenomena of each special 
 gland function, and indeed we can obtain similar slight ferment 
 actions, not only with the glands Kar i^o^vv, but with many 
 other tissues, such as the lungs and the blood. 
 
 Does one secretion prevent the action of another ? The saliva 
 is swallowed in great quantity, and must, as often stated, be 
 rendered inactive by the acid gastric juice ; and, conversely, by 
 its alkalinity it may neutralise or alkalinise the reaction of the 
 gastric juice, so as to stop the pepsin digestion. The latter is 
 possible, but must be very rare, being possible only in the presence 
 
202 LECTURES ON DIGESTION. [Lect. XII. 
 
 of excessive sialorrhcea, and is more imagined in theory than ob- 
 served in practice. At least I know of no such cases either in 
 literature or my own practice, and we could (Ewald and Boas) 
 mix good active human gastric juice with an equal quantity of 
 saliva, without noticeably affecting its digestive power. Sticker 
 has observed that saliva excites the secretion of gastric juice, as 
 in a female patient suffering from dryness of the mouth due to 
 diminished secretion of saliva, with painful dyspepsia, he found 
 the hydrochloric acid of the gastric contents, which was at first 
 diminished, became later on excessive when by appropriate 
 means he was able to stimulate the salivary glands to secrete 
 abundantly. 
 
 The influence on the diastatic ferments of the mixture with acid 
 has been recently investigated in quite a large number of researches 
 — we should name in the first rank the careful and thorough 
 investigations of Professor Chittenden of Pennsylvania — and the 
 general result is that very small quantities of hydrochloric acid, 
 between 0"0005 andO'OOl per cent, increase the amylolytic action 
 of the saliva a little, but that larger quantities diminish or destroy 
 it. Physiological gastric digestion has to do with the formation 
 of great quantities of reducing substances where the food is rich in 
 starch, and this apparently only fails to occur under pathological 
 conditions when there is an excessive formation of acid (hyper- 
 secretio acida). Still we could show (Ewald and Boas) that the 
 quantity of products of starch conversion does not remain the 
 same during a period of digestion, but after a preliminary 
 rise diminishes in proportion to the increase of acidity which 
 during the same time rises from a low figure to its maximum. 
 In general, also, the highest amount of reducing substances corre- 
 sponds to the smallest amount of acid and vice versa. For example, 
 five minutes after drinking a boiled 2 per cent, starch solution, 
 the degree of acidity was O'Oo per cent., and the reduction 
 equalled 0-282 of sugar, and fifteen minutes later, with 0-275 of 
 acid, 0-052 of sugar were found. These figures depend not only 
 on the formation of different mixtures, but, as we have already 
 shown, on the absorption of the products. So that it may be 
 that the reduction figure may remain the same during a long 
 time, even for the whole of an experiment lasting forty-five 
 minutes, whilst the acidity is increasing. At all events the 
 reducing substance is formed in the first minutes or seconds, and 
 
RELATIONS OF THE DIGESTIVE FLUIDS TO EACH OTHER. 203 
 
 the later acidity can only affect the fermentation by controlling 
 it. We must therefore, in order to study the controlling effect 
 of acids on the action of the saliva, proceed as in a laboratory 
 experiment, that is, add the acid to the starch and then drink 
 it. In such experiments it appears that an acidity of hydro- 
 chloric acid of 0'07 to O'l per cent., or of lactic acid of O'l 
 per cent., checks the formation of reducing substances. On 
 the other hand, bile, when it occurs in the stomach under patho- 
 logical conditions, as we proved by experiment, stops the gastric 
 digestion by forming, according to Burkart, a precipitate which 
 mechanically throws down the pepsin. But at the same time 
 you saw that a relatively large quantity was required to effect 
 this, whilst smaller quantities had no influence on the gastric 
 digestion, so that under ordinary conditions, in which only a 
 small reflux of bile occurs, there can be no interference with the 
 gastric digestion. We (Ewald and Boas) have found in our 
 healthy subjects of experiment the gastric contents or its filtrate 
 quite bright green, and have demonstrated the presence of bile 
 pigment by Grmelin's test, but we are not able to decide how far 
 this may have been due to the irritation caused by the introduc- 
 tion of the stomach tube. 
 
 In the duodenum the pepsin digestion proceeds so long as the 
 reaction is still acid ; but as soon as it meets the bile, the syn- 
 tonin and peptones are precipitated, the swollen albuminoids 
 shrink up, and the pepsin is carried down mechanically with the 
 precipitate. Then, with the assistance of large quantities of bile 
 and pancreatic juice, the precipitated albumen becomes redis- 
 solved, and the digestive process recommences. But this 
 description has the fault of being too theoretical, as if things 
 inside the intestine passed through the various phases and dis- 
 tinct stages that we see and learn from our artificial digestion 
 experiments. When we remember that the distance from the 
 pylorus to the opening of the d. choledochus is uncommonly 
 short (about 8 cm.), and that there the bile duct and pancreatic 
 duct open immediately together, and that whilst by the action of 
 the bile the foregoing reactions are proceeding, the pancreatic 
 juice is at the same time present to reverse them, the process 
 cannot be split up into distinct phases, but the actions of the 
 bile and pancreatic juice must be understood to be bound up 
 tofether most intimately. If we allow alcohol and sulphuric 
 
204 LECTURES ON DIGESTION. [Lect. XII. 
 
 acid to act upon each other, ether is formed ; but between the 
 two, ethyl-sulphuric acid occurs, which we do not notice, because 
 it is immediately transformed. Similarly there are no externally 
 noticeable effects of the bile, because its products at once undergo 
 further chemical changes, that is, are subjected to the pancreatic 
 action. Boas has contrived, in accordance with our above de- 
 scribed observation, a simple method of obtaining the contents 
 of the human duodenum by the use of massage to press 
 back the duodenal contents into the empty stomach, from 
 which they are withdrawn by means of a stomach tube. We 
 have already explained that by this method we can derive 
 no new ideas as to the physiological action of the contents of the 
 small intestine, or obtain its mixed secretions. We only get a 
 mixture of the latter plus chyme, and can with it, as Boas has 
 shown, demonstrate the known action of intestinal digestion. 
 On the other hand, it affords a splendid means of studying the 
 opposed action of the gastric juice, or chyme, and the secretion of 
 the intestine. In the first place, it shows that, contrary to the 
 general opinion, the contents of the intestine so obtained are 
 feebly alkaline or neutral, containing abundant bile pigment, yet 
 do not throw down pepsin on the addition of acid or acid gastric 
 juice, or only to a very small extent. If we mix bile contain- 
 ing intestinal contents with an equal amount of gastric juice, so 
 that an abundant thick precipitate takes place, and after leaving " 
 it to stand for twenty-four hours, draw off the upper layer of the 
 mixture with a pipette, and add to it so much stomach filtrate 
 that it contains free hydrochloric acid, it is found to act on 
 albumen. Further, it is found that the addition of hydrochloric 
 acid, in the same degree of concentration as it is met with in 
 the stomach, to bile, which, as is known, putrefies easily, very 
 quickly acts as an antiseptic. Such an acid mixture has no 
 tryptic or saccharifying action. If we dissolve the precipitate 
 by addition of iodine solution we obtain the proteolytic and 
 diastatic action of the pancreatic juice, though this is only pos- 
 sible in the first two or three hours after the mixture is made ; 
 later on no active intestinal contents can be obtained by alkalin- 
 isation, and Boas confirmed the statements of Kiihne and 
 myself, that trypsin is destroyed by peptic digestion, although 
 coming to quite an ojDposite conclusion. It is true that, 
 according to Boas, "the gastric contents freed of ferment by 
 
RELATIONS OF THE DIGESTIVE FLUIDS TO EACH OTHER. 205 
 
 Heat " are equally able to destroy the ferments of the pancreatic 
 juice, and this injurious action must be ascribed only to the 
 eifect of the hydrochloric acid. 
 
 In the subsequent divisions of the intestine, the bile and 
 pancreatic juice co-operate in the digestion of fat, as we have 
 related above. Finally, in how far putrefaction in the lower 
 part of the intestine affects the normal pancreatic digestion, 
 and whether both processes run synchronously, or precede or 
 follow one another, is uncertain. Langley, who has undertaken 
 a methodical investigation of the relations of the digestive 
 ferments to one another, concludes " that the special ferments of 
 the various portions of the digestive tube are each respectively 
 destroyed in the succeeding portion." However, the enzymes, 
 according to F. Falk, appear to possess a great power of resisting 
 the action of putrefaction. But we do not eat albumen, starch, 
 that is hydrocarbon, and fat, or the different organic and 
 inorganic acids and salts, in a pure condition, but take these 
 things in our food in the most complicated and variously 
 compounded shapes. Let us follow some of the most ordinary 
 food on its way through the digestive tract, and see how far, how 
 quickly, and when it is absorbed. This will be scarcely more 
 than a retrospect over the path we have been treading, and the 
 employment of the knowledge we have gained about articles of 
 food, points which, strictly speaking, are included under dietetics. 
 Still we shall not examine the various foods in their composition, 
 digestibility, metabolic importance, and so on, but review various 
 groups in respect to the relations of their nutrient parts to 
 digestion. Once again, as before, I would ask your attention 
 to the dependence of the digestibility of food in a very high 
 degree — a healthy condition of the digestive tract being presumed 
 — upon its penetrability by the digestive fluids. Fats, which we 
 so willingly abuse as indigestible, are decidedly not so. They 
 are easily absorbed, and even a certain degree of rancidity is, as 
 we have seen, rather favourable than otherwise. Naturally they 
 must not be eaten in excess, as in that case all, even the best 
 Swiss milk, is indigestible, that is, it causes mechanical changes, 
 or cannot be absorbed before the whole becomes decomposed, and 
 gives rise to the necessary consequences. The great role which 
 the goodness of the food, its preparation, its composition, the 
 rapidity of eating, and many other things, play in digestion, I 
 
206 LECTURES ON DIGESTION. [Leot. XH. 
 
 dare not enter upon farther. These things belong to dietetics or 
 metabolism. In this place we can only deal with the general 
 principles which are determined in the digestion of the great 
 groups, and we may submit some considerations as to their em- 
 ployment in particular cases. It will be better to take the 
 different groups seriatim, and for simplicity we will regard milk 
 apart from " drinks." 
 
 1. Drinks. — These consist of watery or alcoholic solutions of 
 salts, organic matter, acids, and gases, and are probably completely 
 and rapidly absorbed in the stomach. However, we must not 
 assume that this process is very rapid. I have followed it by 
 introducing a stomach tube as far as the pylorus and connecting 
 the other end to a graduated vertical burette, so that between 
 the mouth of the person experimented on and the lower end of 
 the burette the tube formed a U. When the stomach and 
 the tubes were filled with water, the burette placed at about the 
 height of the cardia, and care taken that the person remained 
 quiet, a communication was established between the stomach 
 and the fluid in the burette, so that the position of the water 
 in the burette represented the level of the water in the stomach. 
 This level naturally oscillated under the influence of the 
 thoracic and abdominal pressure, but the level sank continually 
 lower, though slowly, so that at the end of an hour and a half, 
 for the experiment was not continued longer, it had fallen only 
 10 to 20 cm. We shall say more respecting this and experiments 
 with other drinks in another place. In dilatation of the stomach 
 fluids may remain there an abnormally long time, and then 
 perhaps they undergo decomposition. Thence arises the feeling 
 of fluctuation which we so frequently find on palpating dilated 
 stomachs, and the beneficent results of washing out the stomach 
 in such cases. 
 
 2. Ordinary alhummi. — This in the dissolved condition is 
 probably for the most part converted into peptone in the stomach. 
 If coagulated, it requires a longer time, until the edges of the 
 masticated fragments are dissolved by the operation of the gastric 
 juice. Uffelmann saw the contours of such pieces unchanged after 
 two hours, and the aspect externally under the microscope was 
 that of a finely granular mass. Blondlot found that a dog with 
 a gastric fistula digested 100 grms. of albumen whipped to froth 
 in 3^ hours, and 100 grms. of cooked albumen in 5 hours. We 
 
MILK. 207 
 
 ordinarily regard eggs as pure albumen, and forget tke not un- 
 important yolk contents of fat and salts, the former of wkicli 
 does not become absorbed in the stomach. Yolk of egg is 
 nothing more than an emulsion of fat in solution of albumen, 
 which, according to Proufc, contains 17 per cent, of albumen, 29 
 per cent, fat, and 54 per cent, water. The eggs of the cayman of 
 the Orinoco are used, as Sachs relates, for making oil. 
 
 3. Albumen and fat as milk. — -The coagulation of milk in 
 acid gastric juice begins almost immediately after its intro- 
 duction. It is at first slight, and increases in the first half-hour 
 to its maximum. Casein and fat are gradually separated in 
 more or less compact flocculi or lumps, which are at first 
 sparingly suspended in a milky fluid, but after a short time 
 become more numerous and larger. Therewith the complete 
 separation takes place into curds (fat and casein) and whey (salts, 
 lactose, and water). The latter is absorbed in the stomach. The 
 coagulum consists of closely aggregated fat globules imbedded 
 in an amorphous mass, together with other constituents of the 
 stomach, such as casein, starch granules, and muscular fibres, 
 surrounded by coagula which frequently are covered by mucus. 
 Mother's milk differs from cow's milk not only in its chemical 
 composition but, as Biedert has shown, in the way it curdles, 
 namely, in small flakes, instead of in large lumps. As the work 
 of the digestive juices is facilitated by being able to penetrate 
 more easily and rapidly the material they have to dissolve, we 
 regard this curdling in small flakes as an advantage in mother's 
 milk over cow's milk, and it has been attempted, not without 
 success, to confer upon the latter this property by artificial 
 means. Casein-peptone is formed from these clots partly in 
 the stomach, partly in the intestine, and absorption of this and 
 of the fat takes place. The so-called milk-detritus, which is 
 so often found in the shape of yellowish white flocculi in the 
 stools of healthy infants, consists, according to Wegscbeider, far 
 more of fat, and indeed of olein, palmatin, stearin, and a little 
 peptone, than of unchanged albumen. On the other hand, it is 
 certain that, under pathological conditions of the digestive tract, 
 much unchanged casein, syntonin, and other albuminoids are 
 excreted. Closer investigations are still needed respecting these 
 very important conditions. 
 
 4. Albumen in the form of meat. — It is to be noticed that the 
 
208 LECTUEES ON DIGESTION. [Leot. XII. 
 
 muscular fibrilte are surrounded by the fibrous perimysium, and 
 tiie muscular bundles by tendon and fascia. The gastric juice 
 cannot get at the albumen-containing fibrillEe until these coverings 
 are removed, ruptured, or dissolved. This happens as they are 
 converted into gelatine, and is dependent upon the resistance of 
 the fibres. These are harder in old flesh than in young, and 
 stronger in raw than in cooked meat. By maceration in hot 
 water the connective tissue is softened and removed. The posi- 
 mortem action of acids acts in a similar manner, and we promote 
 this by hanging meat. The muscle-glycogen is changed into 
 lactose, and the connective tissue is loosened by the resulting 
 acid. Raw meat is on this account less easily digestible than 
 cooked meat. But what we lose on one side we gain on the other, 
 as the albumen of the fibrillse is not coagulated, and so is easily 
 peptonised. By cutting up the meat we endeavour to make the 
 connective tissue as small as possible ; and in fact many ill- 
 nourished children and dyspeptic adults digest raw meat better 
 than cooked. lu this respect the so-called steamed meat and 
 underdone roast meat preserve the proper medium. We have 
 discussed already the further transformations of the primitive 
 muscular bundles under the head of gastric digestion. The 
 soluble constituents of meat, such as creatin, creatinin, extractives, 
 salts, &c., are, so far as they are soluble in acid solutions, 
 absorbed in the stomach ; the principal part passes as chyme with 
 the loosened and softened, but not destroyed, fragments into the 
 small intestine, and is then absorbed or transferred to the large 
 intestine, and eventually excreted. The same happens to the fats 
 which are eaten, partly with meat, partly with the accompanying 
 matter. 
 
 5. 'Fat and fatty acids. — These are not absorbed in the stomach 
 and commencement of the duodenum on account of the excessively 
 acid reaction. In whatever form they are ingested, whether 
 alone, whether in combination with other nutriment, or con- 
 tained in the latter, they are always separated from the other 
 constituents and remain intact until acted upon by the bile and 
 pancreatic juice. We have already discussed the details of the 
 process of absorption. But we may add that, according to 
 Ludwig's investigations (Zawilsky), the passage of fat into the 
 lacteals after a copious meal increases up to the fifth hour after 
 taking food, and remains at the same height to the twentieth 
 
VEGETABLES. 209 
 
 hour, then sinks to the thirtieth hour, and about this time ceases 
 with the disappearance of the ingested fat from the intestinal 
 canal. Animal fats are more easily emulsified than vegetable 
 fats, and Gad has proved, in his experiments already described to 
 you, that castor-oil, under the conditions of his experiments, 
 generally forms no emulsion. A not insignificant quantity of 
 fat passes into the faeces, partly as free fatty acids, partly as soap, 
 but a part at present still escapes our observation. Zawilsky 
 found, by simultaneous examination of the gastro-intestinal con- 
 tents, the chyle and the blood, after ingestion of fat, that more 
 fat always disappeared from the intestine than could be found in 
 the chyle and blood. The quantity of fat in the chyle in 
 22 hours=84-l grms., while during this time 132-0 grms. 
 disappeared from the intestine, and other experiments make it 
 extremely probable that this deficit passed somehow directly into 
 the blood. It disappears again tolerably quickly from the blood, 
 as thirty hours after a copious ingestion of fat the blood has 
 regained its normal amount of fat. What becomes of the glycerin 
 derived from the fat, whether it is directly taken up as such, for 
 which the fact of the increase of the liver glycogen after ingestion 
 of glycerin says something, or whether it is decomposed, is 
 unknown. 
 
 6. Vegetables. — Fruits and pot-herbs : we obtain principally 
 from these our necessary hydrocarbons, and, to a less extent, 
 albuminates. Only the most wretched pauperism or the eccen- 
 tricity of the vegetarian allows a vegetable diet to suffice ; yet as 
 we do not live, like savages, on meat alone, the civilisation of the 
 world is bound up with the knowledge of agriculture. But the 
 assimilation of the protein substances contained in them, of the 
 hydrocarbons, organic acids, and salts, is opposed by the difficulty 
 that most vegetables are covered by an envelope of cellulose not 
 easily penetrated by the digestive juices, and carry a ballast of 
 woody cells, epidermis, chlorophyll and other pigments, which in 
 part only undergo absorption. The more, by preparation, boiling, 
 baking, preserving, and the like, we make the cell contents, the 
 digestible matter, capable of being afiected by the digestive juices, 
 the more easily can the hydrocarbons, the sugar and gum, form 
 absorbable solutions, and the proteids, principally casein from 
 altered legumin, be transformed into peptones. Therefore raw 
 pot-herbs, such as salads, are almost entirely unassimilable, and 
 
 14 
 
210 LECTURES ON DIGESTION. [Lbot. XII. 
 
 are excreted nearly unchanged. The digestibility of cooked 
 pot-herbs, fruits, and leguminous vegetables is in proportion 
 as, in cooking, the cellulose is loosened, softened, and the cell 
 contents made accessible. Vegetables possess a nitrogenous 
 constituent, legumin, which is a body resembling casein in all 
 important properties, and gluten, which is very like syntonin, 
 into which plant fibrin and plant gelatine become transformed. 
 This albuminoid becomes in part directly dissolved, in part 
 changed into peptone and so absorbed. Among hydrocarbons we 
 must mention the different kinds of starch and sugar, namely, 
 amylum, dextrin, achroodextrin, inulin, sorbite, &c. ; pectin 
 material, gums and vegetable mucus, especially present in pith, 
 fleshy fruits and roots, which are changed into grape sugar, 
 partly in the stomach, partly in the small intestine, but part of 
 which, n9,mely, the pectin and mucus, remain unchanged ; whilst 
 the relations of a third group, to which inulin, gums, inosite, and 
 sorbite belong, are not yet made certain. I have already described 
 how these hydrocarbons undergo further decomposition by fer- 
 mentation, and what products are formed from them. Finally, 
 we must add the almost overlooked series of organic compounds, 
 which, in part directly with vegetables, in part as mediate deriva- 
 tives of them, serve partly as nutriment, partly as gratification 
 of taste, partly as medicine. They, as well as the inorganic salts, 
 come under observation only so far as they are soluble, or are 
 decomposed into soluble compounds, or can form such. Their 
 absorption occurs chiefly in the upper part of the intestinal tract, 
 and they are of no further interest to us in the study of digestion. 
 Now how far the food is changed and absorbed, and what part 
 not used by the organism is expelled with the faeces, belong to 
 the study of nutrition, which cannot be pursued further here. 
 Only to give an example of the amount of loss by the simplest 
 food in its passage from the mouth to the anus, we may state 
 that Rubner found in a meal of peas a loss of 17'5 per cent, 
 nitrogen, 63'9 fat, 3-6 carbo-hydrates, and 32-5 ash, which were 
 not absorbed, but were excreted in the fseces. Naturally such 
 figures must vary greatly according to the individual and the 
 kind of ingesta. 
 
 There arises another trivial, but still important question in 
 practice. How often and at what times should we take food ? 
 
 Between the extremes of the camivora, which feed once in 
 
MEAL-TIMES. 211 
 
 twenty-four hours or even longer, and tlie herbivora, which, never 
 have done with the business of feeding, man holds a middle 
 place, but not without permitting the recognition in the course 
 of his life of a sort of transition from the herbivore to the 
 carnivore. Infants should have the breast as often as they wake 
 during the first three weeks ; after that, every two hours to the 
 third month ; then every three hours up to the dentition ; and 
 later there should be five meals in the twenty-four hours. The last 
 is also true for adults, provided that the principal and secondary 
 meals alternate regularly. Still the intervals between different 
 meals are often too long, between others too short. It is so par- 
 tially with us, but is especially the case in England and America, 
 where the custom is to eat a large breakfast and then go till 
 evening without eating hardly anything, and at six o'clock to 
 take another meal, naturally then in abnormal quantity. This not 
 only causes inactivity of body and mind, which always accom- 
 panies the digestion of large meals, but is the cause of numerous 
 disorders of the digestive system, especially the stomach. 
 Chronic gastritis, dyspepsia, atony of the mucous membrane, and 
 dilatation of the stomach, result from the excessive irritation of 
 the organ. But while the disproportion al filling of the stomach 
 after a long pause is injurious and irrational, on the other hand 
 our digestive organs are quite capable of receiving moderate 
 quantities of food and digesting them within a given time. 
 Feeding, if very prolonged, or only interrupted by short intervals, 
 as in herbivores and infants, would be an unnecessary waste of 
 labour and time. Under certain pathological conditions and in 
 the convalescence of severe diseases, every patient should in this 
 sense be again an infant or a herbivore. The more often and the 
 less at one time he takes of food, the easier will the enfeebled 
 digestive organs be accommodated. Here the time spent by 
 the physician and the patient in discussing the kind and choice 
 of food will not be lost. 
 
 The time of day for meals follows the distinctions of country, 
 town and city, so that no stringent rules can be laid down. It 
 depends too much upon custom and social conditions. The 
 greatest economy of the day would indisputably be attained if 
 the principal meal were taken in the afternoon somewhere 
 between five and seven, so that there should be four instead of 
 five meals daily. This is physiologically permissible provided 
 
212 LECTURES ON DIGESTION. [Lect. XII. 
 
 there is a ligHt but nutritious midday meal, the luncheon of the 
 English. Then naturally our so-called "abendbrod" (supper) 
 loses its substantial character and is limited to something to eat 
 and drink. For there is nothing more irrational than to take a 
 large meal late at night and just before going to bed. I may 
 remind you of the results of Busch's investigations, which show 
 a complete cessation of the digestive function during the night ; 
 and this is sufficiently confirmed by the broken sleep, restless- 
 ness, nightmares, dreams, bad taste in the mouth, &c., which 
 result from late and heavy meals. Yet these simplest and 
 commonest physiological rules are constantly being transgressed, 
 and an intelligent system of dietetics offers a fruitful field for 
 successful work. The relations between the functions of the brain 
 and stomach are well known, and " inability to sleep at night " 
 originates frequently in a fasting stomach. It is a repeatedly 
 proved experience that sleeplessness after long evening work is 
 cured by taking a little bread, cake, or the like, j list before going 
 to bed. 
 
 So much for these matters, which properly fall within the 
 range of dietetics. 
 
 Gentlemen, I have now reached my appointed limits. We 
 have traced the digestive process through its various stages, and 
 the action of the apparatus which effects this process has been 
 analysed so far as possible in its different phases, in its structure 
 and its various constituents. We may hope that a not distant 
 future will widen the sure field of our knowledge by new and 
 lucid investigations, while we do not seek to conceal that this 
 progressive development, here as elsewhere, will be dangerous to 
 many established, still intact, or already tottering theories. 
 
 As we have seen in the course of our discussion, processes go 
 on in our organism which do not harmonise with the limited 
 application of the combustion theory to the processes of 
 retrogressive metamorphosis, and we gain new support day by 
 day for the view that our body not only, as was formerly 
 supposed, breaks up the ingested nutriment and makes use of the 
 products of decomposition as such, but that it builds up out of 
 these new compounds, and performs not only destructive but 
 synthetic processes ; so we see in the limited field of the subject 
 of Digestion a decided revolution against the theories of the 
 
CONCLUDINa REMARKS. 213 
 
 schools. The hard and fast lines within which the processes 
 of digestion were included, for the sake of, one might almost 
 say, a certain utilitarian principle, attractive as they are by a 
 kind of popular comprehensiveness, can be maintained no longer 
 in their full extent. 
 
 Quite apart from the fact that we now can discern better the 
 ftinctions of the participating glands, especially the pancreas, 
 according to the kind and energy of their action, we were 
 too much inclined earlier to regard the various digestive factors 
 apart from each other, and to make artificial limits which 
 practically do not exist, just as we— especially in considering 
 absorption — used to ascribe too large a field to the action of 
 physiological forces, and too small a field to chemical forces. 
 We have seen how the fermentative actions of various digestive 
 juices resemble each other, how the physiological glandular 
 actions and putrefactive processes are allied to one another, 
 how physical and chemical forces are not separated but work 
 in common, and how, as a new factor, the specific forces of the 
 living cell, which we . provisionally must admit, although still 
 inexplicable, come into play ; in short, how processes take place, 
 in truth, by the co-operation of numerous factors, which some- 
 times aid and sometimes hinder them, and which are more 
 complicated than we can reproduce with our retorts, dialysers, 
 and air-baths, outside the organism ; and still the latter is the 
 unavoidable and correct way to trace the more delicate processes 
 of digestion. Such investigations are of great and primary 
 significance. But we must not forget that under all circum- 
 stances we need the control of experiments on the living organism 
 whenever we can provide the necessary experimental conditions, 
 or a pathological process gives us the necessary material. 
 
 In this matter all of us may assist, and by a single good 
 pathological observation, such as the latest publication of 
 this kind, Demant's researches on the intestinal juice, or 
 my own case of prsetematural anus, and the recent investi- 
 gations of J. Munk, on a patient with a lymphatic fistula, 
 give important aid to scientific medicine. But this requires 
 a knowledge of the present position of the questions svh jiidice, 
 so that you may follow easily the evolution of such a rapidly 
 growing and advancing department of knowledge as the subject 
 of Digestion now is. 
 
214 LECTURES ON DIGESTION. [Leot. XII. 
 
 But we owe physiology still more than we can repay. I need 
 not insist again upon the importance of the knowledge of 
 physiological phenomena for the right understanding and treat- 
 ment of pathological processes. In immediate connection with 
 the experiments of physiologists, in part directly stimulated 
 by them, practitioners have in late years successfully turned 
 these views to account in pathology. Many most excellent 
 clinicists have recently directed their energies to this depart- 
 ment of knowledge. The use of the stomach-pump, nutritive 
 enemata, artificial nutriment, and digestive preparations, gives 
 eloquent testimony to this. When I concluded these " Lectures 
 on Digestion " twelve years ago, I felt warranted in ending with 
 the following words: "But there is still much to be done, 
 and a large field lies open to our common labour. The best 
 result of our meetings would be if they should awaken in you, 
 gentlemen, a new and lively interest in this important branch 
 of our knowledge." To-day this wish has been brilliantly 
 fulfilled. Numerous workers, physiologists and pathologists, 
 have in the last few years taken up the subject of digestion 
 with extraordinary zeal, so that, apart from bacteriology and 
 its triumphs, there is scarcely another branch of our knowledge 
 in which such interest has been taken. How much has been 
 gained, not only of fast-flying chaff, but of sure bases for our 
 knowledge, you may see by comparing the first with this, the 
 third edition of these lectures.. May the future bring equal 
 interest in and an equal measure of work on digestion in its 
 physiological and pathological relations, then the physician will 
 no longer have to complain, as he has to do to-day, in spite of all 
 the work accomplished, of the inadequacy of the diagnosis and 
 treatment of disorders of digestion. 
 
 J. Munk. Ueber die Verbreitung ungeformter Fermente im Thierkorper. 
 
 Deutaoh. med. Wookensohritt, 1876, No. 48. 
 Kuhne. Ueber die Verbreitung einiger Enzyme im Thierkorper. Verhandlnng. 
 
 d. na,turkiBt.-med. Vereina z. Heidelberg, ii. Hft. 1. 
 HUfner. Loo. cit. 
 TJffelmann. Loo. cit. 
 
 Pavy. A Treatise on Pood and Uietetics. London, 1875. 
 Gumilewski. Ueber Resorption im DUnndarm. Pfluger's Arch. Bd. xxiix. 
 
 p. 556. 
 
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