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TREATISE 
 
 ON THE 
 
 MEDICINAL LEECH. 
 
A 
 
 TREATISE 
 
 ON THE 
 
 MEDICINAL LEECH; 
 
 IMCLIDING ITS 
 
 MEDICAL AND NATURAL HISTORY, 
 
 1V1TH A 
 
 DESCRIPTION OF ITS ANATOMICAL STRUCTURE ; 
 
 ALSO, REMARKS UPON THE 
 
 DISEASES, PRESERVATION AND MANAGEMENT 
 OF LEECHES. 
 
 BY 
 
 JAMES RAWLINS JOHNSON, M.D. F.L.S. 
 
 Member Extraordinarj' of tlie Royal Medical Society, Ediiibargli. 
 
 ILLUSTRATED WITH TWO ENGRAVINGS. 
 
 Asl Sutr^spcdysiv TtaiSixcug tyiv tyso) twv drt^ujrscujv 
 sz'io'KS’piy : zv Ttxcri yap ToTa" (puar/Si; svsct) t) ^avp^acrov. 
 
 Aristotle; B. i. c. 5. 
 
 LONDON; 
 
 PRINTED FOR 
 
 LONGMAN, HURST, REES, ORME, AND BROWN: 
 
 SOLD BY' 
 
 CALLOW AND CO. CROWN-COURT, SOHO; BY OLIPHANT, 
 WAUGH AND INNES, AND BLACKWOOD, EDINBURGH; BY 
 BARRY AND SON, FROST, FRY, AND RICHARDSON, BRISTOL. 
 
 ISIG. 
 
John Evans & Co. Printers, 7, St, John-Street, Bristol, 
 
TO 
 
 THE RIGHT HONOURABLE 
 
 Sir JOSEPH BANKS, Bart. K. B. 
 
 PRESIDENT OF THE ROYAL SOCIETY, 
 
 &c. &c. 
 
 THIS TREATISE 
 
 IS 
 
 WITH HIS PERMISSION 
 MOST RESPECTFULLY 
 
 INSCRIBED. 
 
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CONTENTS. 
 
 SECTION I. 
 
 PAGE 
 
 The Medical History of the Leech 1 
 
 § n. 
 
 The Natural History 29 
 
 § m. 
 
 The A)iatomical Structure 85 
 
 § IV. 
 
 The Diseases, Preservation and Management of 
 Leeches 129 
 
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 In compliance with the established rules 
 of the University of Edinburgh, every Medical Student 
 taking his degree, is required to submit to the inspection 
 of the Professors an Essay, either upon the subject 
 of Medicine, or upon some branch connected with 
 it ; and should this essay meet with approval, it is 
 then ordered, after the usual examinations, to be 
 printed. 
 
 Dr. Monro, Professor of Anatomy and Surgery, &c. 
 and then Dean of the Medical Faculty, to whom I 
 presented my Thesis, was pleased to express his appro- 
 bation of the manner in which I had executed it, and 
 advised me to the present publication. This, I must 
 confess, was my original intention ; but I cannot forbear 
 stating, that I publish this Treatise with the more con- 
 fidence, as it comes forward under so respectable a 
 sanction. 
 
 The Thesis alluded to (Disputatio Physica inauguralis 
 qusedam de Hirudine complectens, Ed. 1814) forms the 
 outline of the present attempt. 
 
X 
 
 PREFACE. 
 
 Having acquired from my Father, In early life, a 
 taste for Natural History, I have felt the greater interest 
 since I took this subject in hand ; but am constrained to 
 ohserv^e, that an expression of regret was unwillingly 
 drawn from me, on finding, notwithstanding the Im- 
 portant services the Leech renders in Medicine, and its 
 extensive employment among the Greek and Roman 
 Physicians, that we should be still so ignorant of its 
 Natural History. And such regret will, it is probable, 
 long continue ; for what is greatly to our disadvantage, 
 all the operations of this useful animal are carried on 
 beneath the waters, and thus evade our research ; and 
 the habits of the Leech, influenced as they must neces- 
 sarily be in a state of confinement, will scarcely advance 
 us a single step in obtaining any thing like satisfactory 
 information. 
 
 I still however trust that I have brought forward all 
 the evidence 1 could collect, either from the writings of 
 naturalists, &c. or from enquiries made among those 
 who were likely in any respect to forward my views. 
 And here it would ill become me to omit naming 
 Dr. T. W. Dyer, of Bristol, and Mr. Hebb, Surgeon, 
 of Worcester ; to whom I stand particularly indebted, 
 no less for the handsome and ready manner in which 
 my enquiries were replied to, than for the information 
 thus acquired. 
 
PREFACE. 
 
 XI 
 
 In the Section including the Medical History, the 
 principal object I have had in view, is to shew that the 
 Leech was frequently in use among the Ancients, and 
 was thought highly efficacious in removing or at least 
 lessening the influence of disease. And that this was 
 not without a just foundation, may be fairly inferred 
 from its being one of the few remedies possessed by the 
 Ancients, which has continued down to the present day, 
 with increased reputation. 
 
 The description of the Anatomical Structure of the 
 Leech, I have given at some length, from the circum- 
 stance of its being so remarkably singular, and from 
 having been enabled, by frequent dissection, to confirm 
 or disprove the assertions of preceding writers. I may 
 perhaps, by many, be considered to have erdarged un- 
 necessarily ; but I would rather on that account incur 
 censure, than have failed to give every part of this inter- 
 esting subject a full and deliberate discussion. 
 
 The observations offered in the last Section, regarding 
 the Preservation of Leeches, will, I hope, be of service 
 to those who keep them, and be the means of lessening 
 the mortality, of which there are such frequent and loud 
 complaints. 
 
XU 
 
 PREFACE. 
 
 If in bringing forward this Treatise I have merited the 
 commendation of the physiological enquirer, I shall con- 
 sider myself amply rewarded, and be better contented 
 to bear, in silence, the remarks of those who have the 
 same aversion to the study of Natural History with my 
 illustrious namesake; who, after the departure of a 
 gentleman who had been amusing a friendly party by 
 giving the Natural History of the Mouse, satirically 
 exclaimed, “ I wonder what he would have said, if he 
 had seen a Lion !” 
 
 J. R. JOHNSON. 
 
 Bristol, Jan. 1816. 
 
SECTION THE FIRST. 
 
 The Medical History of the Teecli. 
 
 n^HE first introduction of the Leech 
 into medical practice was doubtless suggested 
 by its having been seen to pierce the skin of 
 various animals, and gorge itself with their 
 blood. The peasantry, it is probable, had 
 long noticed this, and from observing no ill 
 effects to follow their bite, might have been 
 emboldened to make on themselves, as oc- 
 casion required, trial of their efficacy. 
 
 The circumstance of the Leech being 
 found to remove a certain quantity of blood 
 from the circulating system without pro- 
 ducing any ill effect^ was the strongest re- 
 commendation in its favour ; and the crude 
 
2 
 
 notions then entertained, of diseases taking 
 their orig'in from various humours generated 
 in the system, must have contributed to its 
 more immediate and extensive employment. 
 
 Agreeably to this idea, we feel little or no 
 surprise that the Leech should be regarded 
 by the Ancients as one of their first and most 
 effectual remedies. Indeed Zacutus Lusita- 
 nus gives us this direct information, in the 
 following passage. “ Nam post celeb rata 
 praesidia universalia, ad Hirudiiiem, tanquam 
 ad sacram anchoram, veteres necessitate 
 quadam coacti, accedebant.” 
 
 In the writings of Hippocrates, we find 
 no notice of the Leech ; and Coelius Aureli- 
 anus quotes nothing concerning it, in the 
 extracts he gives us from the writings of 
 Diodes, Praxagoras, lierophilus, and other 
 physicians, who lived between the times of 
 Hippocrates and Themison. 
 
 Themison, who flourished in the first 
 years of the Christian aera, and, as we learn 
 
3 
 
 from Seneca, was the founder of a new 
 sect in medicine, called the Methodic Sect, 
 and greatly praised for the excellency of his 
 writings by Democrates and Pliny, was the 
 first who wrote on the utility of the Leech 
 in medical practice. He was in the habit of 
 applying a cupping-glass, after the Leech 
 had quitted its hold, for the purpose of ex- 
 tracting a larger quantity of blood. What 
 success attended him in this practice, he does 
 not inform us., Celsus, however, remarks, 
 that he was very skilful, and enjoyed a high 
 reputation for the cure of various diseases ; 
 but in Juvenal we meet with the following 
 Philippic. 
 
 “ Quot aegros Themison autumno Occident uiio.” 
 
 Satyra x. v. 22]. 
 
 Antyllus, who flourished not long after 
 Themison, had very frequent recourse to 
 Leeches, when either the patient feared the 
 lancet, or from an inequality or roughness of 
 
 B 2 
 
4 
 
 the surface, he was prevented from using the 
 cupping-instrument. They do not, he in- 
 forms us, suck the blood from the internal 
 parts, but only from those contiguous to the 
 skin. When the hands or feet require their 
 application, he directs these parts to be im- 
 mersed in water in which Leeches are kept. 
 
 Menemachus, who also lived at an early 
 period of the Christian aera, found in several 
 diseases an excellent remedy in Leeches ; 
 but the number to be applied, he observes, 
 must depend upon two circumstances — the 
 size of the part and tlie nature of the 
 affection. 
 
 Pliny, who flourished during the reigns 
 of Tiberius, Vespasian, and Titus, by the 
 last of whom he was greatly esteemed, and 
 to whom he dedicated his diffuse and la- 
 borious work on Natural History, speaks of 
 the great service Leeches are reported to 
 produce in cases of Gout, and warmly recom- 
 mends their application, in various diseases. 
 
5 
 
 to the hsemorrhoidal veins. He also informs 
 us, that the ashes of a burnt Leech, sprinkled 
 over or formed into a kind of paste with 
 vinegar, will remove hair from any part of 
 the body to which it is applied. This prac- 
 tice is also noticed by Q. Serenus, in the 
 following verses. 
 
 “■ Nec non quse stagnis cessantibus haesit Hirudo 
 Sumitur, et vivens saniia torretur in olla ; 
 
 Haec acidis jungit permixta liquoribns artus, 
 Avulsamque vetat rursus percrescere Silvam.” 
 
 Some little notice is said to be taken of 
 Leeches, in a paper ascribed to Galen, De 
 Cucurbitulis, De Scarificatione, De Sangui- 
 sugis, &c.” but this appears to have a slight 
 foundation ; as Galen was far from giving in 
 to the opinions of the methodic sect, who 
 were in the frequent habit of using them ; of 
 which sect Themison, as before remarked, 
 was the founder, and Antyllus and Menema- 
 chus the zealous partisans. 
 
 Aretaius recommends the use of Leeches 
 
6 
 
 in Angina accoinj)anied with Dyspnoea, and 
 advises tlieir application to the hips in Saty- 
 riasis. The most learned of the ancient 
 physicians, he informs us, preferred their use 
 to the taking away blood by other means, 
 from the idea of their being capable of re- 
 moving any offensive humour from the body, 
 however deeply it might be seated. 
 
 Oribasius, who flourished about the year 
 330, wrote on the advantage of extracting 
 blood by Leeches. In a chapter devoted to 
 Inflammations of the Eyes, he recommends 
 their application to that side of the forehead 
 corresponding to the part affected. 
 
 tEtius, who lived in 445, in his treatise 
 “ De atra Bile sive Melancholia,” mentions 
 his successful application of Leeches, in all 
 cases in which the liver was affected. 
 
 ^GiNETUS, who flourished in the early 
 part of the seventh century, takes occasion, 
 in pointing out the method of curing the 
 pain of the head in Fevers, to mention 
 
r 
 
 Leeches, and advises them to be applied, 
 the head being previously shaved, to the 
 occiput. 
 
 Actuarius, of whom it is recorded that 
 he practised medicine with the greatest suc- 
 cess at Constantinonle, recommends their 
 adoption in those instances where there is 
 reason to suppose tliat corrupt and putrid 
 blood has been collected. In cases where 
 we dare not open a vein or apply the cup- 
 ping-instrument, they have, he says, when 
 opportunely applied, the happiest effect, and 
 in various affections of the Head, constitute 
 our best remedy. 
 
 Alexander Benedictus describes leech- 
 bleeding as highly advantageous in cases of 
 Vertigo, especially if the Leeches are applied 
 behind the ears. Their application also to 
 the gums will, he says, allay rheumatic 
 pains of the Teeth. 
 
 Arnoldus recommends their speedy adop- 
 tion where a wound has been inflicted by a 
 
8 
 
 rabid animal, observing, that a due quan- 
 tity of blood should be afterwards taken 
 away by nieans of the cupping-glass. 
 
 Gariopontus speaks of their efficacy in 
 Lethargy, when applied to the fore and 
 back part of the head ; and in Epilepsy, 
 arising from melancholy, when applied to 
 the region of the spleen. 
 
 Hieronymus Mercurialis, who was in 
 such high esteem as a physician, that he was 
 sent for to Rome, to attend Pius IV. was in 
 the frequent habit of employing them, al- 
 though he imagined they were not altogether 
 capable of removing the whole of the evil of 
 which the patient might complain ; for the 
 orifice, he remarks, made by the Leech, is so 
 small, that none but the thinner portions of 
 the blood can escape ; the thicker part, 
 from which he supposes the evil to arise, 
 being still retained. 
 
 Horatius Augenius, in his treatise De 
 Sanguinis Missione,” contemns bleeding 
 
9 
 
 children by means of the lancet, and advises 
 Leeches as a substitute. 
 
 Leonardos Botallus received, in the 
 course of his practice, the greatest benefit 
 from Leeches, when applied to the smaller 
 members of the body, as the ears, nostrils, 
 fingers, &c. An old Leech, he informs us, 
 is of little or no use ; and a Leech that has 
 once bitten should be laid aside, as it is sel- 
 dom found to go through its accustomed 
 office again. 
 
 Mundella recommends the application 
 of Leeches to an inflamed leg, and to the 
 haemorrhoidal vein, in all cases of continued 
 Fever. 
 
 Petrus Salius, in his treatise on Fevers, 
 spealts highly in their praise, observing that 
 they effectually remove the humours at that 
 time generated. 
 
 Zacutus Lusitanus asserts, that the 
 Leech not only draws blood from the veins 
 contiguous to the skin, but also from deeply 
 
 c 
 
10 
 
 seated parts of the body ; hence its uti- 
 lity in Fevers deriving their origin from a 
 thickened state of the humours. To mode- 
 rate violent pains of the temj)les, he disposes 
 tiiem in a circular manner, to the number 
 of ten or twelve on each temple. He 
 gives the case of a man witli a painful 
 affection of the hip, who was bled both in the 
 ankle and in the arm, without experiencing 
 the slightest relief ; but on applying eight 
 large Leeches over the part affected, the 
 patient was free from his complaint within 
 the space of a few hours. This author 
 also relates a case of Phrenitis, arising 
 from a retention of the menses ; for the 
 cure of whicli, as other remedies had failed, 
 he ordered four Leeches to be fastened 
 by a piece of thread, and then applied as 
 closely as possible to the uterus. From the 
 quantity of blood thus lost, the delirium was 
 removed, and the woman in a few days 
 recovered. Z. Lusitanus is so warm an 
 
11 
 
 advocate for their employment, that he de- 
 clares there is no disease but will become mild 
 under this mode of treatment, and particu- 
 larly should the Leeches be applied to the 
 vessels of the anus. What inclines him to 
 this opinion is, the close connexion which 
 exists between the haemorrhoid al veins and 
 other parts of the body ; lienee all olrending- 
 humours may be easily removed. 
 
 ’We might with but little trouble trace the 
 medical history of the Leech down to the 
 present time ; but this I conceive unnecessary. 
 Enough has been already said to prove, that 
 its introduction into the school of medicine 
 is of ancient date ; and every day’s expe- 
 rience serves to confirm the reputation it then 
 so justly acquired. 
 
 Notwithstanding the Leech was thus 
 highly valued, the Ancients were afraid of 
 the ill consequences that might arise from 
 
 c 2 
 
12 
 
 having- swallowed one by accident; v/e there- 
 fore find in their writings a long list of reme 
 dies suited to each particular case.* 
 
 Oribasius recommends the person who has 
 the misfortune to swallow a Leech, to drink 
 jfientifully of vinegar ; but a better remedy 
 
 * These apprehensions were not^ it will be seen^ ill 
 grounded. “ When the French army entered upon the de- 
 serts which separate Egypt froni Syria, the soldiers, pressed 
 by thirst, threw themselves on their mouths and nose, and 
 drank greedily of the muddy water they met with, and 
 which, unknown to them, contained Leeches, having the 
 form of a horse-hair, and being only a few lines in length. 
 Many of them felt immediately stings or prickling pains in 
 the posterior fauces, follow'ed by frequent cough, glairy 
 spots lightly tinged with blood, and a disposition to vomit, 
 with a difficulty of swallowing, laborious respiration and 
 sharp pains in the chest, loss of appetite and rest, attended 
 with great uneasiness and agitation. On pressing down 
 the tongue of the individual first attacked, a Leech was 
 discovered, which was with difficulty removed by the 
 forceps. Little or no hsemorrhage followed, and the 
 patient recovered. Leeches that had attached them- 
 selves to the posterior fauees, were removed by the use of 
 gargles composed of vinegar and salt-water. The Chief of 
 Brigade, Lateur Mauberg, commander of the 22d Regiment 
 of Chasseurs, sw'allowed two in the desarts of St. Makaire, 
 a day’s journey from the Pyramids ; which so much weak- 
 ened him, that his convalescence was long and difficult.” — 
 Med. and Phys. Journal. 
 
13 
 
 than all, he says, is garlic ; which, from its 
 heating property, soon expels them. 
 
 yEtius informs us, we may readily know 
 wlien a Leech has been swallowed, by the 
 burning sensation which the patient expe- 
 riences in his stomach and throat. If the 
 pain is confined to the stomach,* he recom- 
 mends a large draught of salt-water in which 
 assafoetida has been dissolved, or the remedy 
 
 * Should the Leech reach the stomach, it probably would 
 not long survive: for it appears from an experiment made 
 by Dr. Stevens on an Hussar, whom he describes as gaining 
 a miserable livelihood l)y sw’allowing stones for the amuse- 
 ment of the common people, and from which practice his 
 stomach was so much distended that he could swallow seve- 
 ral stones at a time, that the Leech is (contrary to what one 
 would suppose) acted upon by the gastric fluid. The Doctor 
 enclosed one of these animals alive, in a silver sphere per- 
 forated with small holes, and gave it to the Hussar to swal- 
 low ; who voided it in about four and twenty hours ; when 
 nothing was found except a black viscid miasma, the re- 
 mains of the digested Leech. This experiment, on a first 
 view', it might be imagined, militates against the opinion of 
 that ingenious physiologist, John Hunter; who states that 
 the human stomach, on account of the vital principle it 
 possesses, is never, during life, acted upon by the gastric 
 fluid ; nor is any other substance, he remarks, that is simi- 
 larly endowed. In all likelihood, the vital principle of the 
 
14 
 
 of which he speaks favourably, shoemaker’s 
 blacking' (atramentum sutoriiim) dissolved 
 in vinegar. If the pain be felt in the throat, 
 the patient, he says, would do well to retain 
 in his mouth two or three spoons-fnll of cold 
 water ; which often answers the purpose of 
 luring the Leech from its retreat. Sternuta- 
 tories should by no means be unemployed : 
 the best are those composed of hellebore and 
 elaterium. 
 
 Avicenna, who flourished in the year 980, 
 of whose professional attainments the Ara- 
 bian writers speak highly, advises the poor 
 sufferer to take garlic and wormwood, mus- 
 tard, and other acrid substances, and to re- 
 frain from speaking. 
 
 Leech was extinct before the gastric fluid began to exercise 
 its effects ; and I have the stronger reason for supposing this 
 to have been the case, from the circumstance to which I 
 shall soon advert, of one Leech fll. Vulgaris) living within 
 the body of another (H. SangiimigaJ, nearly three days. 
 
15 
 
 Leeches, according to the opinion of 
 ancient writers, are unfit for medical pur- 
 poses when they are of a very red or black 
 colour. If these, they say, should be unfor- 
 tunately applied, they immediately give rise 
 to Fever, Diarrhoea, and S}mcope, and some- 
 times even produce inveterate ulcers. To 
 prevent these ill effects, they recommend 
 their being chosen with small heads and of 
 a brown or green colour. They should also 
 have longitudinal lines on the back, and be 
 taken from waters where there is an abun- 
 dance of frog-s. 
 
 Previously to their application, the An- 
 cients recommend them to be thrown into 
 water moderately warm, and afterwards 
 placed on a piece of sponge, that by moving 
 over it they might rid themselves of the viscid 
 humour, virus, or oil, as they term it, attached 
 to their surface. To induce them to fix on 
 the skin the more readily, the part affected 
 
16 
 
 was frequently punctured with a lancet ; 
 or when this was not consented to, blood 
 or milk was applied to the skin, with the 
 same intention. When the Leech was firmly 
 applied and in the act of suction, advan- 
 tage was now and then taken of snipping 
 off the tail.* By this method, we are in- 
 formed, one Leech will answer the purpose 
 of several ; for it still continues drawing the 
 blood as before, which flows drop by drop 
 from the wounded extremity. 
 
 To make the Leech disgorge the blood, the 
 Ancients were in the practice of sprinkling 
 over its surface the muriate of soda (common 
 salt) and vinegar ; and to restrain the bleed- 
 ing, when profuse, they relied upon the ap- 
 plication of bole armeniac, powdered aloes, 
 and sometimes applied to the bleeding ori- 
 fice a sponge dipped in liquid pitch. 
 
 * This was the case, 1 find, so early as the time of Pliny. 
 
ir 
 
 If a Leedi at any time remained affixed 
 longer than ordinary, it was a common prac- 
 tice to expose it to the fumes arising from 
 burnt hair or wool ; or in case this did not 
 succeed, a horse-hair was inserted Iretween 
 its mouth and the part to ^vliich it was at- 
 tached ; the Ancients being umvilling to 
 dislodge it by forcibly tearing it awav, lest 
 its teeth might be left in the wound, and tlius 
 prove fatal ; which we are told by Pliny, 
 happened to Messalinus, one of the patrician 
 consuls. 
 
 Altliough many of the notions entertained 
 by the Ancients relative to the Leech are 
 highly erroneous, yet we must allow they 
 justly appreciated its value in several dis- 
 tressing diseases. The Moderns, however, 
 while they reject many of their crude and 
 
 D 
 
18 
 
 imdigested ideas, are equally aware of its 
 importance ; but acting upon more correct 
 and scientific principles, obtain greater and 
 more extensive advantage from its use. 
 
SECTION THE SECOND. 
 
 The Natm'al History of the Leech. 
 
 In regard to the genus Ilinido, 
 much confusion at present prevails, solely 
 attributable to the jdacing and rehiiniiig in 
 that genus several animals in no respect 
 corresponding to the generic character as 
 given by Linnoeus. 
 
 Dr. Shaw, after remarking that among 
 the variety of the smaller animals there are 
 many that have no place in the Systema 
 Natura of Linnaeus, proceeds to the descrip- 
 tion of what he has denominated a new 
 English Leech, to which he assigns the name 
 of Hirudo viridis, giving its specific cha- 
 racter in these words : H. viridis ohlonga, 
 
20 
 
 extremitate acutmscula. “ It is fomid,” he 
 says, “ in such waters as are more than com- 
 monly clear and cold, or at least such as do 
 not very easily freeze during a common frost. 
 It is about an eig’hth of an inch in length, 
 bears a resemblance to the II. complanata, 
 and is in colour of a deep grass-green, with 
 a transparent edge or border. It has two 
 eyes, of a deep black. Its motions are ana- 
 logous to those of the II. complanata, H. 
 stagnalis, and II. octoculata ; but it pos- 
 sesses a greater degree of contractile power, 
 since it often assumes a shape approaching 
 to a circular outline. Its general motion is 
 an uniform smooth progression, occasionally 
 varied by a circular movement, as if turning 
 slowly on an axis.”* 
 
 A description of three new species of 
 Hirudo has been also given by the Rev. 
 ’William Kirby ; the Hirudo alba, Hirudo 
 nigra, and tlie Hirudo crenata. 
 
 * Linn. Trans, vol. i. p. 93. 
 
21 
 
 IIiRUDo CRENATA. H. subdeprcssa subo- 
 vata striata, striis transversis annularibus, 
 margine cremdato. 
 
 “ This species is of a greenisli cast, some- 
 times in dining* to asli-coloiir, with transverse 
 annular strim, from whence arise the crenatm 
 of its margin. Its upper surface is somewhat 
 convex. Its interanea are very visible, owing 
 to its vitreous transparency. It has two eyes 
 only, which are very much approximated. 
 Its motion is very similar to that of the larvae 
 of the Geometrce, and is performed by means 
 of the adhesive property of the head and 
 tail.”* 
 
 The Hirudo alba (H. depressa alba in 
 teraneis fiiscis ramosis margine crispante, 
 extremitate acutiuscida), and the Hirudo 
 NIGRA (H. depressa nigra linearis abdomine 
 nigro) described in the paper from which 
 the above is copied, have now taken their 
 place in the genus Planaria. 
 
 * Linn. Trans, \ ol. ii. p. 316. 
 
22 
 
 The H. crenata, from Mr. Kirby’s descrip- 
 tion, answers so closely to that of the//, com- 
 jilanata, that 1 should take them to be one 
 and the same, had not this gentleman de- 
 clared that the H. crenata possesses two eyes 
 only ; and we find in the H. complanata as 
 many as six.* It is a singularity, however, 
 worth notice, that the figure of the H. cre- 
 nata, accompanying his description, should 
 be delineated with six eyes, and moreover 
 shew a retractile tongue, which he does not 
 even so much as notice. From this circum- 
 stance I cannot but think the //. complanata 
 has been figured by mistake for the //. 
 crenata. 
 
 ]\Ir. Kirby in conclusion remarks, “ the 
 //. alha, II. Jiigra, and also the II. viridis of 
 Dr. Shaw, appear to me not rightly referred 
 
 * The H. complanata, cornpressetl between two plates of 
 glass, exhibits six eyes; but subjected to no such pressure, 
 the eyes are so closely set, that they appear to coalesce, 
 favouring an idea, upon a cursory survey, of this species 
 having two eyes only. 
 
23 
 
 to this genus (Hirudo), as they by no means 
 agree with the Linneean definition, Corpus 
 oblongum ore caudaque in orbicuhim expan- 
 dendis se promovens. The motion of these 
 three species is uniform and equable, nor do 
 they possess that orbicular adhesive expan- 
 sion of the head and tail which constitutes 
 the essential distinction of the genus Hirudo. 
 Qu. are they sufficiently distinct to consti- 
 tute a new gemis ?” 
 
 Dr. Shaw, in reply, observes, that “ the H. 
 nigra is probably the Planaria fiisca, and 
 the H. alba the Planaria lactea of Gmelin. 
 The H. viridis comes so near to the Planaria 
 punctata, viridis, and Helluo, that it may be 
 doubted whether it be really distinct, or a 
 variety.” 
 
 These several species are now found in 
 Turton’s British Fauna, under the genus 
 Planaria ; but in the Encyclopedia Londi- 
 nensis the H. viridis, notwithstanding the 
 statement of Dr. Shaw, in which he admits 
 
24 
 
 the impropriety of so naming it, is still re- 
 tained in the genus Hirudo. 
 
 The Hirudo complanata and the Hirudo 
 slagnalis are similarly situated. They have 
 a character dLssimilar to the Leech ; 1st, in 
 being fnriiislied with a retractile tubular 
 tongue ; 2d, in having a flattened body ; 3d, 
 in attaching themselves, not by any expan- 
 sion, but by an adhesive property of the head 
 and tail. This dissimilarity, therefore, leads 
 me to constitute a new genus, to which, from 
 the prominent feature of the retractile tubular 
 tongue,* I give the name from 7XT3-o-(ra, a 
 tongue, and crKpwv, a tube, of 
 
 * In reference to this retractile tongue, but without con- 
 sidering it to be tubular, we find, in Muller, the following 
 passage: “Articuluin spiculi forma, quern clarissimus Berg- 
 MANN II. complanatam ore exserere vidit, et cujus usum se 
 ignorare fatetur, nunquam etiamsi per plures hebdomadas 
 inquirerem, observavi, at II. vulgarem vldi organum tale ore 
 protrudere et retrahere, quo viso, dictus articulus Berg- 
 manni mihi in mentem venit, cum vero intra minuta pauca 
 totum spiculum projecerit, mox patuit, esse vermiculum aqua- 
 ticum, quern exsuctum evomerat. Ita autor facile in erro- 
 rem induci potuerit.” Hist, Verm. 1/74. p. 4D. This remark 
 
25 
 
 GLOSSIPHONIA. 
 
 Character Generis. 
 
 Corpus subovalum depressum, caput acu- 
 minatum, lingua tubulata, os caudamque 
 alteme affigendo pvogredieiis. 
 
 G. Tuberculata, 
 
 OLIM 
 
 H. COMPLANATA.* 
 
 Glossiphonia dilatata, supra cinerea, liiiea 
 duplici tuberculata, subtus grisea, atomis 
 nigris inuumeris. 
 
 of Muller does not in the slightest degree invalidate the 
 assertion of Bergniann. In observing the movements of the 
 H. complanata and H. stagnalis, I have occasionally seen this 
 tongue protruded, in which state it usually remained a few 
 seconds, being thrown from side to side, in a waving direc- 
 tion, and then gradually withdrawn. It is thicker at its 
 point than at its base, and may at any time be brought into 
 view by gentle compression between two plates of glass. 
 By means of this retractile tubular tongue, these animals 
 are enabled to draw up, as through a siphon, the animalculsc 
 in the water which constitute their food. 
 
 * This species, when touched, buries its head under its 
 body, and rolls itself up, somewhat after the manner of an 
 Oniscwt. 
 
 E 
 
26 
 
 Oculi sex — more delineato, ;• 
 
 Long’. Line® octo. 
 
 In Rivulis. 
 
 LiNNiEus, Syst. Nat. XIT. "2, p. 1709, n. 6. 
 
 Faun. Suec. *2082. Hinulo depressa ovato- 
 
 oblonga interaneis fuscis pinnatis pellucen- 
 tibus. 
 
 II ILL, rUst. Anhn. p. 16. Hirudo lateribus attenuatis. 
 
 Bergmann, Act. Stoclch. 1757, tab. vi. fig. 12, 14. Hirudo 
 sexoculata. 
 
 Muller, Hist. Verm. 2, n. 157, p- 47. Hirudo compla- 
 nata. 
 
 G. Perata,* 
 
 OLIM 
 
 H. Stagnalis. 
 
 Glossiplionia gracilis, cinereo - viridis, 
 piinctis pliirimis subnigris. 
 
 Oculi duo — more delineato, 
 
 * I have given this animal the specific name of Perata, 
 from the circumstance of its having an abdominal pouch, to 
 shelter its young. If this pouch should be common to any 
 other species that may hereafter fall under this genus (not 
 having seen such in the G. TuberculataJ, the name will of 
 course be inappropriate, and must be changed. 
 
27 
 
 Long. Lineae octo. 
 
 In Rivnlis. 
 
 LinnjEus, Syst. Nat. XII. 2, p. 1079, n. 5. 
 
 Faim. Suec. 2081. Hirudo (stagnalis) depressa 
 
 nigra, abdomine subcinereo. 
 
 Muller, Hist. Verm, 2, n. 1/1, p. 41. Hirudo bioculata. 
 Bekgmann, Act. Stockh. 1757, n. 4, tab. 6, fig. 9 — 11. Hi- 
 rudo bioculata. 
 
 This species has an abdominal pouch, in 
 which the young, after their exclusion from 
 the ova, are sheltered, and in which they 
 remain (occasionally leaving it) for some 
 weeks, adhering by their tails, and enjoying 
 a free extent of motion with the rest of the 
 body. The G. Perata is remarkable also 
 in being enabled to move on the top of the 
 water, its belly being uppermost, as freely as 
 in any other position. 
 
 A Leech has been described, inhabiting 
 the Thames, under the name of Hirudo cir- 
 culans,* but it is clear that it cannot belong 
 
 * Sowerby’s British Miscellany, tab. 76. 
 
 E 2 
 
28 
 
 to that genus, when we read the description 
 of it, which runs thus: Oblong, pointed 
 towards the head, coiivex above, flat beneath, 
 dull red ; and equally clear, that if it be fur- 
 nished with tlie retractile tubular tongue, 
 regarding which I have little doubt, it will 
 fall under the genus Glossiphonia. The 
 body of this species is about an inch in 
 length, convex, and obscurely striate on the 
 upper side, flat, and paler beneath. 
 
 The Ilirudo crenata of Mr. Kirby will 
 be probably found to belong to the same 
 genus. 
 
 This remark may equally apply to one or 
 more, still retained in the genus Hirudo ; but 
 until the propriety of their removal be fully 
 ascertained, it ^vill be proper that we retain 
 them in their original situation. 
 
 We shall now proceed to the consideration 
 of this genus, distributed into two divisions ; 
 the first including those Leeches found in 
 
29 
 
 rivers or in stagnant waters ; the second, 
 tliose found in the sea. 
 
 HIRUDO. 
 
 Character Generis. 
 
 Corpus oblonguin subrotmidum, anterius 
 et posterius tmiicatum, muticum, cartilagi- 
 neiim, os caiidamqiie dilatando progrediens. 
 
 Hirudiiies in Rim's, Stagnis, Paludibusque 
 habitantes. 
 
 H. Medicinalis. 
 
 Himdo depressa nigricans, supra lineis 
 flavis sex, intermediis nigro arcuatis, sub- 
 tus cinerea nigro rnaculata. 
 
 Oculi decern,* more delineato, I • 
 
 * No Leech has been hitherto described Avith more than 
 eight eyes. In the H. medicinalis and H. sanguisuga, no 
 notice has been before taken of an organ of vision. 
 
.‘30 
 
 Long. Poll ices tres. 
 In Stag'nis — Paludibus. 
 
 Caput — (|uiescens subrotunduin, progre- 
 diens acuininatuin. 
 
 O.S— quoad figuram miitabile, rimam tri- 
 angularem plemmque exhibens. 
 
 Cauda — circularis, coinplanata, fibris car- 
 nosis e puncto centrali divaricatis. 
 
 LiNNjEUSj 
 
 Hill, 
 
 Gesner, 
 
 Muller, 
 
 Barbut, 
 
 Wesek, 
 
 Ber&mann, 
 
 Gisler, 
 
 Saloman, 
 
 Shaw, 
 
 Pennant, 
 
 Sijst. Nat. XII. 2, j). 107f), n. 2. 
 
 Faun Suec. 2079. 
 
 Hist. Aiiim. p. 16‘. Ilirudo nigrescens flavo va- 
 riegata. 
 
 Pise. 425. tab. 425. Hirudo major ct varia. 
 Hist. Vermium, 2. n. 1G7, p. 57- 
 Genera Vermium, p. 19, tab. 2, fig. 5. 
 Amcenitates Academicce, tom. vii. p. 42. 
 
 Act. Stockh. 1757 , p. 308, n. 4, tab. 6, fig. 1, 2. 
 Ibid. 1758, p. 95. 
 
 Ibid. I 7 GO, p. 35. 
 
 Naturalist's Miscellany , tab. 218. 
 
 British Zoology, vol. iv. p. 36. 
 
 H. Sanguisuga. 
 
 Hirudo elongata fusco-viridis, subtus ci- 
 nereo virens, inaculis nigris. 
 
31 
 
 Oculi decern. 
 
 Long’. Pollices tres. 
 
 In Stagnis — Locisque palustribns. 
 
 LiNNjEUS, 
 
 Weser, 
 
 Hill, 
 
 R A Ills, 
 
 IMuller, 
 
 Bergmann, 
 
 Gisler, 
 
 Barbut, 
 
 Shaw, 
 
 Petiver, 
 
 Syst. Nat. XII. *2, p. 1070^ n. 3. 
 
 Faun. Suec. 2078. 
 
 Amcenitates Acadernicce, tom. \'n. p, 44. Hirudo 
 depressa fusca; margine lateral! flavo. 
 
 Hist. Anirn. p. 16. Hirudo nigra abdomine 
 plumbeo. 
 
 Ins. 3. Hirudo inaxime vulgaris. 
 
 Hist. Verm. 2, n. 168, p. 38. 
 
 Act. Stockh. 1757 , n. 4, tab. 6, fig. 3, 4. 
 
 Ibid. 1768, p. 95 — 2. 
 
 Genera Vermium, p. 20, tab. 2, fig. 6. 
 
 Naturalist's Miscellany, tab. 218. 
 
 Gazopli. Naturce et Artis, tab. 130, fig. 7- 
 
 H. Troctina.* 
 
 Hirudo elongata fusca, supra aniiulis aureis 
 
 * I am not aware of this species having been hitherto de- 
 scribeil. 1 have denominated it Hirudo Troctina, from its 
 resemblance, in regard to the coloured rings or spots, to the 
 Trout, and also from its being known and sold in the shops 
 under the name of the Trout-Leech. Owing to the great 
 scarcity of the medicinal or striped Leech, it has been latterly 
 employed in medicine. 
 
32 
 
 niaculas atras ciiigentibus, margine sub-flavo 
 lateral!, siibtus flavo-viridis pimctis atris. 
 
 Oculi decern. 
 
 Long*. Pollices tres. 
 
 Ill Rivis — Piscibus crebro adhasrens. 
 
 H. Nigra.* 
 
 Hirudo elongata, per totmn corpus, niger- 
 rima. 
 
 Oculi decern.^ 
 
 Long. Pollex. 
 
 This is here described as a new species ; how far I am 
 correct in this particular remains to be ascertained. The 
 whole of the body is of a deep jet-black ; which, on being 
 held up to the light, exhibits several transparent bladder- 
 like bodies, ranged along the sides. This species I preserved 
 upwards of eight months. It is the only one of the kind I 
 have ever seen, and was found in a rivulet near Bristol. It 
 had all the external character of the Leech, but in its ha- 
 bits presented an essential difference. It Avas remarkable for 
 its inactivity, was commonly coiled up, and seldom took to 
 the water. 
 
 f I'he eyes of the H. nigra, H. troctina, and H. sanguisuga, 
 present the same figure as those of the II. medicinalis, in p. 20. 
 
33 
 
 In Rivulis. 
 
 H. Vulgaris.* 
 
 Hirudo elongata flavo-fusca, supra lineis 
 nigris transversis, subtus immaculata. 
 
 Oculi, more delineato, octo. 
 
 Long. Poll, ly- 
 
 In Rivulis. 
 
 LinnjEUS, Syst. Nat. XII. 2, p. 1079, n. 4. 
 
 Faun. Suec. 2080. Hirudo (octoculata) depressa 
 
 fusca, punctis octo nigris supra os. 
 Bergmann, Act. Stockh. 1756, p. 199 — 1757, tab. 6, fig. 
 
 5, 8. 
 
 Muller, Hist. Verm. 2, n. 170, "p. 40. 
 
 H. Tessulata. 
 
 Hirudo dilatata cinerea, margine tessulato, 
 supra maculis albis vel aurantiis, subtus gii- 
 sea, maculis duabus albis. 
 
 Oculi octo. 
 
 * Having kept, during the last summer, several of this 
 species, I noticed this circumstance, — that they deposit th^ir' 
 ova at two periods of the year, the months of July and 
 October, 
 
 F 
 
34 
 
 Long. Poll. 1^. 
 
 In Rivis — rara. 
 
 Muller, Hist. Verm. 2, n. 173, p. 45. 
 
 H. Lineata. 
 
 Ilimdo elongata grisea, clorso lineis qua< 
 tuor longituclinalibus nigris. 
 
 Ociili sex. 
 
 Long. Poll. 1^. 
 
 In Paludosis — rara. 
 
 Muller, Hist. Verm. n. 169, p. 39. 
 
 H. Heteroclyta. 
 
 Himdo dilatata, pellucida, flava, punctis 
 atris striata, margine integro. 
 
 Oculi quatuor.* 
 
 * The H. Heteroclyta is sometimes seen with six eyes j 
 and what is remarkable, Muller once observed one of this 
 species, with four eyes, bring forth young, “ quatuor et sex 
 oculis gaudentes.” Hist. Verm. 1774, p. 50. 
 
35 
 
 LiNNjEUS, 
 
 Muller, 
 
 Trembley, 
 
 Ledermuller 
 
 Himdo 
 
 albis. 
 
 In Rivis 
 
 LiNNjEUS, 
 
 Hill, 
 
 Frisch. 
 
 Raes. 
 
 Muller, 
 
 Bergmann, 
 
 RiESEL. 
 
 Long'. Linea? octo. 
 
 In Rivulis. 
 
 Syst. Nfit. XII. p. lOSO, n. 7- 
 
 Hist. Verm. n. I76', p. 49. Hiriulo hyalina. 
 
 Hist. Polyp, tab. 7, fig- 7. 
 
 Microscop. p. l6'5, tab. 84, fig. k, q. 
 
 H. Geometra. 
 
 elongata, flavo-viridis, maculis 
 
 Oculi quatuor. 
 
 Long. Linese octo. 
 
 -Piscibus creberrime adbaBrens. 
 
 Syst. Nat.'Kll. “i, 1080, n. 8. 
 
 Faun. Suec. 2083. Hiriulo teres extremita- 
 tibus dilatatis. 
 
 Hist. Anim. p. 17- Hirudo dorso elevato, 
 cauda latiore. 
 
 Ins. 6, p. 25, tab. 11. Hirudo ore caudaque 
 ampla. 
 
 Ins. p. 399, tab. 32. Hirudo piscium. 
 
 Hist. Verm. 2, n. 172, p. 43. Hirudo pis- 
 cium. 
 
 Act. Stockh. 1757 , p. 310, n. 3. 
 
 App. tab. 32, fig. 1, 4. 
 
 F 2 
 
36 
 
 Ledermuller, Microscop. tab. 84, fig. a. i. 
 
 Barbut, Genera Vermium, p. 20, tab. 2, fig, 7. 
 
 Pennant, British Zoology, vol. iv. p.3S, tab. 20, fig. 13. 
 
 II. Marginata. 
 
 liimdo dilatata, fusca, margine tessulato, 
 subtus siibliiissime stiiata.* 
 
 Oculi qiiatuor. 
 
 Long. Pollex. 
 
 In Rivis — rara. 
 
 Muli.er, Hist Verm. 2. n. 174, p. 4b, 
 
 Hirudincs in Oceano hahitantes. 
 
 H. Indica. 
 
 Ilirudo depressa, fusca, striis muricatis 
 transversis. 
 
 In maritimis. India. 
 
 * All the Leeches hitherto described, with the exception 
 of H. lineata, H. tessulata, and H, marginata, are to be met 
 with in this island. 
 
H. Grossa. 
 
 Hirudo dilatata, subflava, striis albis pul- 
 cherrimis. 
 
 Ill Oceaiio. 
 
 Muller, Zool. Dan. 1. p.69, n.27, tab. 21, fig. 1, 5, prodr. 
 p. 2668, rar. 1, p. 43. 
 
 H. Hippoglossi.* 
 
 Hirudo dilatata subalbida, supra versus 
 caput maculis cinereis duabus, siibtus versus 
 caudam liiiea tuberculata. 
 
 In Oceano — cuti Pleuronectis Ilippogiossi 
 adheerens. 
 
 Muller, Zool. Dan. 2, tab. 54, fig. 1, 4, prodr. p. 2669, 
 rar. 2, p. 41. 
 
 O. Fabr. Faun. Grcenl. p. 302, tab. 1, fig. 8. 
 
 Raster, Opusc. Subsec. p. 138, tab. 8, fig. 11. 
 
 * It appears from a passage in Muller, that this species 
 will occasionally move in the water after the same manner 
 as the G. Perata. “ Praeter hunc incessum (more geometrarumj 
 alium in hac specie observavi inversum nempe, dum corpora 
 supino summum aquae ore et cauda alternatim prehendit.’' 
 Hist. Verm. 2, p. 51. 
 
,38 
 
 H. Branchiata. 
 
 t 
 
 Ilirudo depressa atteiiuata alba, setis la- 
 teralibus ramosis iitriiique septein, iiiteraiieis 
 fuscis bifidis perlucentibus. 
 
 In Oceano Pacifico — Testudini adlias'rens. 
 
 Tram. Linn. Soc. vol. i. p. 188, tab. 17, fig. 3. 
 
 H. Muricata. 
 
 Ilirudo elongata tuberculata, versus cau- 
 dam maxime dilatatam attenuata, caput 
 bicorne. 
 
 In Oceano septentrionali— Piscibus creber- 
 riine adliaerens. 
 
 LinnjEus, Faun. Suec. 2084. 
 
 Rondeletius, 2, p. 111. Hirudo marina. 
 
 Raster, Opusc. Subsec. 1, p. 82, tab. 10, fig. 2. Hi- 
 
 rudo piscium. 
 
 Baebut. Genera Vermium, p. 20, tab. 2, fig. 8 
 
 Mas. Adolph. Fred. 1, p. 93, tab. 8, fig. 3. 
 British Zoology, 4, p. 38, tab. 20, fig. 14. 
 
 Pennant, 
 
39 
 
 H. Verrucosa.* 
 
 i 
 
 Himdo elongata rotunda, annulis plurimis 
 verrucosis. 
 
 In Oceano Haice clavatce adhserens. 
 
 Encyclopedie 7^- liv. des PI. d’ Hist. Nat. Helminthologie, 
 pi. 52. fig. 5. 
 
 Mem. Wernerian Nat. Hist. Soc. 2, p. 245. 
 
 Having* tlius brought into view tlie whole 
 of the genus Hirudo, we shall now pass on 
 to the Natural History, more particularly 
 as it relates to that species employed in 
 Medicine. 
 
 * We are indebted for a full description of this species, 
 which bears a close resemblance, with the exception of its 
 having no horns on the head, to the H. Muricata, to the 
 Rev. John Fleming, who introduced it to the notice of the 
 Wernerian Natural History Society, in a paper since pub- 
 lished in their Memoirs. 
 
40 
 
 The Leech has received from almost all 
 nations, an appellation corresponding to 
 its well-known property of attaching itself 
 to the skin, and thence drawing the 
 blood. By the Greeks it was named 
 (by Nicander, 4)jAa<jw,ar©", and by 
 Theocritus, from its inhabiting marshy situ- 
 ations, ^.iixvriTii) ; by the ancient Romans, 
 Ilirndo, or, without the aspirate, Irudo ; and 
 by the modern Romans, Scmguisuga.* By 
 some Italians it is called Sanguisuca ; by 
 others, Sanguettole ; by the F rench, Sansue, 
 Sangsue or Suce-sang ; by the Germans, 
 Mgle, or Egle, or Blut-egle ; by the Ger- 
 mans of the Low Countries, Lake, or Lyclce- 
 
 * Pliny, in describing the natural history of the Elephant, 
 makes this remark. “ Cruciatmn in potii maximum senti- 
 unt, hausta Hirudine, quam Sanguisugam vulgo coepisse 
 appellari adverto.” — Nat. Hist. tom. 1. p. 440. To this 
 passage we find subjoined the following note : “ Itaque 
 Plinii sevo sanguisuga a suctu sanguinis coepta est appellari. 
 Qui certe Scriptures an tea vixerunt, Hirudinem constanter 
 vocant.” The Leech was thus called Hiruda, from liaurio, 
 expressive of its well-known peculiar action. 
 
41 
 
 lake ; by the Danes, Dokter-iglen, or Blod- 
 igle, and by the Poles, Pijavvka. In India, 
 it receives the appellation, in the Hindustani 
 language, of Jonc; in the Sanscrit language, 
 of Jelauca. 
 
 The Medicinal Leech is common through- 
 out the whole of Europe, but more so in the 
 southern than in the northern parts. It is about 
 three inches in length ; but in the southern 
 parts of America and India it is often found 
 to be six or seven inches. Formerly this 
 species was very abundant in our island ; 
 but from their present scarcity, owing to their 
 being more in request among medical men, 
 and to the rapid improvements which have 
 of late years taken place in agriculture, 
 particularly in the draining and cultivation 
 of waste-lands, we are obliged to receive a 
 supply from the Continent, chiefly from 
 Bourdeaux and Lisbon.* These Leeches 
 
 * On a moderate calculation, we employ at least one hun- 
 dred Foreign Leeches for every British Leech. I give this 
 
 G 
 
42 
 
 differ from the Medicinal Leech of this 
 country, in being’ larger, and having the 
 belly of one uniform colour. 
 
 Leeches are observed to take their predo- 
 minant or ground-colour, from the colour of 
 the soil in which they are found. Mr. Baker, 
 a man of some intelligence, residing in Glas- 
 tonbury, and who for the last twenty years 
 has been in the habit of collecting large 
 quantities of Leeches for sale, informs me 
 that at the Back River, near Glastonbury, 
 they are black, from the peat being of that 
 colour ; at Cook's Corner, they are of a red- 
 dish cast, from the red peat ; and at Auler 
 Moor, where from a deficiency of peat they 
 penetrate the clay, they are yellow. This 
 assertion receives some support from its being 
 remarked of the toad, that if it be much ex- 
 posed to the light, its colour changes to that 
 
 as the opinion of a person who has for many years been a 
 Leech-Dealer, and whose occupation enables him to give 
 this statement on very satisfactory evidence. 
 
43 
 
 t)f a pale green ; but when it remains in the 
 earth, and is not uncler its influence, it gene- 
 rally acquires the colour of the substance 
 which surrounds it.* The H. tessulata is 
 said to vary so much, in respect to colour, 
 that unless it were continually observed, it 
 would be taken for a different species. 
 
 Notwithstanding Leeches are thus subject 
 to this change, they still offer spots or lines 
 which are considered permanent, and upon 
 which we may safely rest in giving their 
 specific character. 
 
 The motion of Leeches in water resembles 
 that of the Eel. They swim in a serpentine 
 direction, and at times with considerable 
 velocity. Besides this, they have a creeping 
 motion, and are capable of moving the an- 
 terior extremity of their body, either forward 
 or backward. When the Leech wishes to 
 change its place, the circular muscles with 
 
 * Fyfe’s Comparative Anatomy^ p. 232. 
 
 G 2 
 
44 
 
 which it is furnished are called into action i 
 the diameter of the body being in this M'^ay 
 lessened, the extension of the head is effected. 
 Its attachment is then made secure by the 
 sucker terminating that extremity. One 
 point of attachment thus gained, the longi- 
 tudinal muscles act in their turn, and draw 
 the tail towards the head. The tail is then 
 fixed by means of a similar sucker, and the 
 head, by the re-action of the circular mus- 
 cles, is again thrown forward. By these 
 alternate movements, the Leech is enabled 
 to move on a solid surface with great 
 facility. When the Leech quits the 
 bottom of pools, to reach the surface 
 of the water, the body is projected at full 
 length in an oblique position, and is then 
 moved in a waving direction, upward and 
 downward. By this action briskly repeated, 
 the Leech is thrown forward, and soon 
 accomplishes its purpose. 
 
45 
 
 In winter. Leeches resort to deep water ; 
 but in summer they delight in the shallows, 
 where they are more exposed to the influence 
 of the Sun. When the weather is very 
 severe in winter, or so dry in summer as to 
 endanger the total drying up of the pools 
 they inhabit, they retire to a considerable 
 depth in the ground, leaving a small aper- 
 ture to their subterranean habitation. They 
 begin to make their appearance in the wa- 
 ter about the latter end of March or the 
 beginning of April. During a bright sun- 
 shine they may be seen very actively swim- 
 ming from place to place ; but should the 
 weather prove cold or cloudy, they confine 
 themselves to the mud. In rainy or windy 
 weather, when the water is agitated, they 
 retire from sig:ht. Just before a thunder- 
 storm, they commonly come up to the sur- 
 face; and this the Leech-Gatherers find a 
 good time for collecting them. 
 
46 
 
 Leeches are said to jjreclict changes in the 
 weather, with so much accuracy as to serve 
 for Barometers. 
 
 A Clergyman residing in France found 
 that a Leech, enclosed in a glass vessel half 
 filled with water, and kept in a window of 
 his chamber, answered every purpose of a 
 Barometer. Each morning, he informs us, 
 the Leech had shifted its position, in strict 
 unison witli the varying state of the atmos- 
 phere. F'rom attentive examination, he was 
 enabled to acertain, — first, that when the 
 weather was about to be serene and pleasant, 
 the Leech remained at the bottom of the 
 vessel without the least movement ; secondly, 
 that if it was about to rain, in either the fore 
 or after noon, it mounted to the surface of the 
 water, and there remained until the return of 
 fine weather ; thirdly, that on the approach 
 of boisterous weather, it moved in the water 
 with uncommon swiftness, and never ceased 
 from this motion until the wind began to 
 
47 
 
 blow; fourthly, that on the approach of 
 weather attended with thunder and rain, it 
 remained out of the water for several days, 
 appearing agitated and restless ; fifthly, that 
 it rested constantly at the bottom of the 
 vessel when a frost was about to commence ; 
 and sixthly, that during the time of snow 
 or rain, it fixed itself at the neck of the vessel, 
 remaining at perfect rest.* Cowper, the 
 celebrated author of The Task, has asserted 
 that Leeches, ‘‘ in point of the earliest intelli- 
 gence, are worth all the barometers in the 
 world.” Although I cannot agree with our 
 poet, I will not say that Leeches are unaf- 
 fected by the weather, since this is sufficiently 
 proved by their restlessness on its various 
 changes ; being affected in like manner with 
 those animals of which the Mantuan bard, in 
 speaking of an approaching shower, gives so 
 natural a description. 
 
 * Vide Supplement to the JEncyclopedie ou Dictionnaire 
 Raisonne des Sciences ; article ^ Sangsue,' tom. 4, p. 733. 
 
48 
 
 Aut ilium surgentem vallibus iniis 
 Aerise fugere grues ; — aut bucula coelum 
 Suspiciens, patulis captavit naribus auras : 
 
 Aut arguta lacus circumvolitavit hirundo : 
 
 Et vetercm in limo ranae cecinere querelam. 
 
 Georg, lib i. v. 374. 
 
 How far the remarlis of eitlier the French 
 Clergyman or the Poet are worthy of notice, 
 will appear by observing vessels in which 
 Leeches are contained. Some Leeches will 
 be seen in a state of rest, others in motion ; 
 some at the bottom of the water, others at 
 the surface. I would therefore ask how it 
 is possible they can furnish any thing like 
 accurate indications of the state of the 
 atmosphere ? 
 
 The food of the Medicinal Leech is stated 
 to consist of the larvae of aquatic insects, 
 worms, &c. These, it is true, constitute the 
 food of the Horse-Leech (II. sanguisuga)y 
 but not that of the Leeches in medical use 
 (H. jneclicinalis and H. troctina), which 
 
49 
 
 subsist by feeding on the fluids of fish,* 
 frogs, &c. A few memoranda on this sub- 
 ject may not prove uninteresting. 
 
 Having procured a Frog, I placed it in 
 a vessel containing half a dozen Leeches 
 (H. medicinaLis and H. troctina), in which 
 floated a piece of deal. The poor animal, 
 finding itself surrounded, made every ef- 
 fort, but ineffectually, to reach the upper 
 part of the float ; while its enemies pursued 
 it with more than common activity. At 
 length one of the Leeches settled on the 
 back, and the others affixed themselves to 
 the legs. On the following morning the F rog 
 was found dead, presenting, on different 
 parts of its body, no less than eighteen 
 wounds, all bearing the usual triangular 
 appearance. 
 
 Being in possession of a common Water- 
 Lizard (Lacerta palustris), I placed it in 
 
 * Leeches are frequently found afiixed to that sj)ecies of 
 salmon, called the Shewen — S. Eriox. 
 
 H 
 
50 
 
 a vessel with four Medicinal Leeches. The 
 Ijceches swam ahout, unconcerned, and the 
 l^izard was removed in the course of a few 
 hours, untouched. This inditlerence on the 
 part of the Leeches, I attributed to their late 
 feast upon the Frog’. Four days afterward 
 I replaced the Lizard, which had then lost 
 somewhat of its activity, in its former situ- 
 ation, and had scarcely time to cover the 
 vessel, before two of the Leeches began the 
 attack by wreathing themselves around their 
 prey, for tlie purpose of securing a firm hold. 
 In a few minutes a wound was inflicted. 
 The Ivizard, hitherto motionless, now strug- 
 gled violently to release itself. This struggle 
 was continued at intervals, but without effect, 
 for about half an hour ; when the Lizard 
 yielded to its fate. 
 
 I have frequently placed the common 
 Earth-Worm (Lumbricus terrestris) in ves- 
 sels with Medicinal Leeclies, but never found 
 it to receive the slightest injury ; which is the 
 
51 
 
 more singular, as the Earth-Worm contains 
 red blood, a fluid for which the Leech shews 
 great partiality. I have also presented to 
 them different kinds of aquatic larv^, but 
 never observed tlie least disposition on tlicir 
 part to injure them. So far otherwise, tliat I 
 have often witnessed the larvae of tlie larger 
 Water-Beetle (Dytisens marginalis) in the 
 act of seizing the Leeches by means of their 
 mandibles. Hence it is sufficiently manifest, 
 that neither the Earth-Worm nor the larvae 
 of aquatic insects constitute their food. 
 
 It may not be here out of place to mention 
 a few similar experiments relative to the 
 Horse-Leech ; which differs from the Medi- 
 cinal Leech, in possessing a voracious appe- 
 tite, and in swallowing solid food. 
 
 In an early period of my investigation, I 
 accidentally broke a phial in which was a 
 Medicinal Leech. This I placed, unconscious 
 of the consequence, in a glass vessel contain- 
 
 H 2 
 
52 
 
 ing about forty Horse-Leeches. In a short 
 time, I observed the Leeches to be clustered 
 togetlier, and the Medicinal Leech making 
 great efforts to recover its liberty. On se}3a- 
 rating them, I found the latter to have 
 received three wounds, of which it soon 
 recovered when replaced with its own species. 
 This led me to the following experiments. 
 
 I procured a large-sized Medicinal Leech, 
 gorged with blood, and presented it to about 
 thirty Horse-Leeches. As soon as the Me- 
 dicinal Leech saw the others in motion, it 
 endeavoured to avoid them by swimming to 
 the surface. It was how ever in a little time 
 seized upon and dragged to the bottom of the 
 vessel. In a few minutes the water had as- 
 sumed a bloody tinge, and the Leech was 
 quickly deprived of life. To ascertain whe- 
 ther the Medicinal Leech was destroyed 
 merely from the natural ferocity of its enemy, 
 or to serve as food, I repeated the experiment, 
 taking care previously to feed the Horse- 
 
53 
 
 Leeches with Earth-Worms. This done, I 
 presented to them two Medicinal Leeches, 
 whicli immediately swam to the surface, and 
 attached themselves to the upper part of the 
 vessel, in order to avoid their enemies. This 
 effort, however, might have been spared, for 
 the H. sanguisugcE did not make the slight- 
 est attempt to molest or in any way injure 
 them ; it is therefore evident that they are 
 destroyed solely for food. 
 
 I counted, in a glass vessel in which they 
 were contained, sixty-five Horse-Leeches. 
 Five days afterward, 1 found the number 
 reduced to fifty-two. No less, therefore, than 
 thirteen, had in the short space of five days 
 been destroyed ; not even a vestige was left 
 to denote their former existence. 
 
 Two of tlie common Rivulet-Leeches (H. 
 vulgaris) were presented to a Horse-Leech. 
 In a short time, I observed the head of one 
 of the former in the mouth of the latter, who, 
 by the force of suction alone, drew the whole 
 
54 
 
 animal into its stomadi. This operation 
 look no a (quarter of an hour. Its gluttony, 
 liowevcr, was not satiated, until it had 
 swallowed tiie other. Three days after- 
 ward, one of these Leeches was thrown 
 up in a living state, appearing to have suf- 
 fered but little injury from its conlinement, 
 and was, alter the lapse of a few hours, again 
 swallowed. 
 
 It seems almost incredible that one Leech 
 should remain within the stomach of another 
 nearly three days, and yet be rejected alive. 
 My friend Dr. M‘Dougall was uj)on a visit 
 to me at this time, and with another gentle- 
 man, had an opportunity of witnessing this 
 singular occurrence. 
 
 Having observed a I4orse-Leech to seize 
 and swallow one of the small Leeches (H. 
 vulgaris), I placed it aside, and in two hours 
 opened the body. The H. vulgaris ap- 
 peared, on a first view, nearly destitute of 
 life; in the course of an hour it began to 
 
55 
 
 move, and by the day following had regained 
 its former activity. It was kept in a vessel 
 by itself. On the fifteenth of July, twelve 
 days from its liberation, it produced an 
 ovum, and one also on each of the fol- 
 lowing days, viz. the 16th, ITth, 22d, 24th, 
 27th, 29th, 31st, and August 4th, 9th, and 
 16th. On the 22d it died. I have com- 
 pared these ova with tlie ova of the same 
 species met with in rivulets, and find an 
 exact resemblance.* 
 
 Desirous to ascertain how many of the 
 smaller Leeches would be swallowed in a 
 given time, I kept two Horse-Leeches in 
 
 * I frequently, during the month of July, procured the 
 ova of the H. vulgaris, from the rivulets in which these 
 Leeches are found, and had the satisfaction to find them 
 productive. These ova are, when first produced, of a briglit 
 amber-colour, gradually deepening to a dull brown. They 
 are usually of an oval form, convex above and flattened 
 beneath ; but they take this figure only when agglutinated 
 to any surrounding object; being, when deposited in an 
 unattached state, mostly globular. On opening these ova, 
 or, more correctly speaking, capsules. I have several times 
 taken from each, from six to eight j'oung, in colour of a 
 grey-white, and of the size of the finest sewing-thread. 
 
56 
 
 separate vessels for a month, supplying them 
 constantly with the H. vulgaris^ both in its 
 dead and living state. * 
 
 During the whole of this period I must 
 observe the water was turbid, notwithstand- 
 ing its occasional renewal, from the vast dis- 
 engagement of foecal matter which floated 
 about, having a thread-like appearance. 
 
 Swallowed by No. 1. 
 
 June 10, two, (le;ul ... .2 
 12, two, living. ... 2 
 15, one, living. ... 1 
 
 20, two, dead .... 2 
 
 21, one, dead .... 1 
 23, one, living. . . . 1 
 25, two, living. ... 2 
 29, two, living. ... 2 
 
 July 3, one, living. ... 1 
 9, one, living. ... 1 
 
 Total, 15 
 
 Swallowed by No. 2. 
 
 J une 10, one living and 
 
 one dead. ... 2 
 
 11, one, dead . . . . 1 
 
 12, one, living. . . . 1 
 
 16, one, living. . . . 1 
 
 17, three dead and 
 
 one living. ... 4 
 
 19, three, living . . .3 
 
 20, three, living ... 3 
 July 2, two, dead ....2 
 
 8, two, living. ... 2 
 
 9, one, living. ... 1 
 
 Total, 20 
 
 On the fifteenth of June, three H. sangui- 
 sugce swallowed three H. vulgares. On the 
 20th, I opened the three, and could not, in 
 
57 
 
 two, trace the least vestige of a Leech. la 
 the third, I found a Leech about half di- 
 gested, surrounded by a fluid in colour of a 
 deep brown. The intestine in the others 
 was filled with a similar fluid, but much 
 thicker in point of consistence. 
 
 This experiment, with the preceding table, 
 cannot but convince us of the activity of the 
 digestive powers in the H. saiig uisuga. This 
 indeed may be also determined by a refe- 
 rence to its anatomical structure. In the H. 
 sanguisuga, the intestine is more than double 
 the width of that of the H. medicinalis and 
 H. troctina ; and the stomach is not so 
 thickly set with membranous folds or parti- 
 tions. A difference therefore in regard to 
 food necessarily arises, from this difference of 
 structure. 
 
 To the general law in cold-blooded ani- 
 mals, that digestion proceeds with great 
 
 I 
 
58 
 
 slowness,^ the experiment just mentioned 
 otters a marked exception. 
 
 The digestive powers of the H. sangui- 
 suga are ])robably more active during the 
 summer than during the s])ring months. 
 Trembley, the author of an interesting me- 
 moir on Poli/pes, has observed, that the in- 
 fluence of the weather greatly affects the 
 digestive powers of those animals (^Polypes); 
 for when the weather is sultry, the same 
 quantity of food is completely digested in 
 twelve hours, as in a moderate temperature 
 requires two or three days. 
 
 To several Horse-Leeches I presented 
 some Elvers, in a dead state, and about 
 three inches in length. As soon as I per- 
 ceived a Leech in the act of swallowing one 
 of them, I removed it from the rest, with the 
 
 * We learn from that indefatigable experimentalist, 
 Spallanzani, that a Lizftrd, after remaining sixteen days 
 in the stomach of a Viper, was found to have lost nothing 
 of its original form — a remarkable instance of the extreme 
 slowness of the digestive powers in cold-blooded animals. 
 
59 
 
 view of observing it more closely. Appa- 
 rently with the greatest ease, it received, into 
 its stomach the major part of the Elver, about 
 two inches, but was unable, with all its 
 efforts, to take in more. Finding it could 
 not accomplish its purpose in swallowing the 
 whole, and sensible of its motions being eui- 
 barassed by what it retained, it fixed its tail 
 closely to the side of the glass, and drew 
 backward its head, and in this maimer gra- 
 dually shortening itself, was enabled to reject 
 the recently swallowed food. 
 
 From this experiment we see that the H, 
 sanguisuga enjoys the privilege of voiding 
 by the mouth any thing it may be unpleasant 
 to retain — a circumstance often observed in 
 respect to Birds of Prey, who have the power 
 of throwing up the feathers and hair of the 
 animals they devour. 
 
 Fothergill relates the circumstance of a 
 Tench (Cyprinus tinea) which was taken in 
 the river Ouse, and put into a stone-trough, 
 
 I 2 
 
60 
 
 full of water, that stood in a pasture-field, for 
 the use of cattle. A number of Leeches (H. 
 sangmsugcs) inhabiting the spring that sup- 
 plied the trough, came and surveyed the 
 Tench, and at length affixed themselves to 
 different parts of its body. So effective was 
 their hostility, that the Tench was quickly 
 deprived of life. They then tore it (pre- 
 viously breaking the line of connexion be- 
 tween the various parts of the body, by 
 inflicting a vast number of bites or wounds) 
 into such pieces as they could readily receive 
 into the stomach. So diligent and perse- 
 vering were they, that in a few days nothing 
 but the mere skeleton of the fish remained.* 
 
 A circumstance of a similar nature is also 
 recorded by Klein. -f 
 
 * Essay on the Philosophy, Study, and Use of Natural 
 History, p. 222. 
 
 f “ Ante aliquos annos in fundo meo civitatis inferioris 
 Cyprinos breves sive Carassos in Fiscella servaveram, quos 
 omnes post triduum ab Hirudinihus consumptos inveni, non 
 nisi sceletis superstitibus.” HerpeUdogia, p. 66. 
 
61 
 
 It would be useless to bring forward any 
 
 more experiments. I shall only observe, 
 that I have varied them in every possible 
 shape, and have obtained from them this 
 information : 
 
 1st, That the Medicinal Leech takes no 
 kind of solid food. 
 
 2dly, That in its native abode, it lives 
 by adhering to and sucking the fluids of fish, 
 frogs, &c. 
 
 3dly, That its desire for food is not 
 marked by that voracity which distinguishes 
 the Horse-Leech. 
 
 4thly, That it does not display the same 
 propensity to destroy its own or any other 
 species of the genus to which it belongs. 
 
 In regard to the Horse-Leech, we must 
 remark, 
 
 1st, That it destroys for food, the H. 
 
62 
 
 medicinalis, the II. vulgarisy and shews 
 as little mercy to tlie weaker of its own 
 species. 
 
 2dly, That this unsocial propensity ap- 
 pears to be put in force in the absence of 
 other food. 
 
 3dly, That it will swallow almost any 
 thing presented to it. 
 
 4thly, That the name of II. Vorax is 
 more expressive of its real character, than 
 that of II. Sanguisuga. 
 
 Like the Hydra of ancient times. Leeches 
 are stated to liave the remarkable property 
 of reproduction. Dr. Shaw observes that 
 this is very conspicuous in the smaller kind 
 of Leeches, the II . stagnalis, II. complanata, 
 and H. octoculata ; in which animals it 
 almost equals that of the Polype. The 
 doctor’s experirnjents were made in 1773. 
 To use his own words, “ These animals 
 were divided in every possible direction ; and 
 
63 
 
 the divided parts, after reproduction, were 
 again sub-divided and ag-ain reproduced, 
 without the failure of one single instance.”* 
 These experiments I have repeated, but with 
 this wide difference, that I met with a failure 
 in every instance. Let facts speak for 
 themselves. 
 
 June 29th, I divided four Leeches (H. 
 octociilata), each into two equal parts. 
 Four of these parts preserved their vitality 
 till September 3d. During the whole of this 
 period, the only change noticed was, that the 
 angles of the divided extremities were less 
 acute : not the slightest tendency was evinced 
 towards reproduction. 
 
 July 1 4th, three of the H. complanata (now 
 
 G. tuberculata) and the same number of the 
 
 H. stagnalis (now G. perata) were divided 
 each into two equal parts. Those of the H. 
 stagnalis lost their vitality in ten days. The 
 vitality of the divided portions of the H. 
 
 * Linn. Trans, v. i. p. 9.5. 
 
64 
 
 cumplanata continued until the 6th of Sep- 
 tember, but with a result similar to that which 
 attended the division of the H. octoculata. 
 
 June 29th I took two Horse-Leeches, and 
 cut off the head of one, and the head and 
 tail of the other. These Leeches I have still 
 by me (December 12th); but I cannot trace 
 in either the slightest tendency towards re- 
 production. 
 
 I treated also, after the same manner. 
 Medicinal Leeches, and with a similar 
 result. 
 
 Many, says Muller, might be easily led 
 into an idea, that an animal whose mem- 
 bers when separated possess for a great 
 length of time their vitality, is capable of 
 reproduction ; but, he judiciously adds — aliud 
 enim est vitam in singulis partibus aliquam- 
 diu remanere, hasque se movere ; aliud in 
 totidem abire animalia: illud pluribus ani- 
 malium commune est, hoc minus vulgare.* 
 
 * Hist. Verm. 1774, p. 9. 
 
65 
 
 III aiiotlier place this author observes, what 
 is more to the point, that he has endeavoured 
 to ascertain how far this power of reproduc- 
 tion in Leeches exists ; but all his expe- 
 riments go to prove that Leeches have no 
 reproductive power whatever. * 
 
 The Leech is reported, in common with 
 other animals, to be infested u ith lice. I 
 mention this on the authority of Klein,'f' 
 never having myself witnessed them. 
 
 We come now to that part of the Natural 
 History of the Leech which is the most in- 
 tricate to develope ; its mode of propagation, 
 and the duration of its life. 
 
 In confinement, it is a very rare occurrence 
 
 * ‘‘ Plurima (Helminthica) per partitionem naturalem 
 et artificialem transversam propagantur ; utramque in Hy- 
 dris, Naidibus, et Lumbricis, ego et ante me alii docuere ; 
 artificialem in Hirudinibus vero, et Gordiis frustra tentavi.” 
 —Hist. Verm. 1774, p, 9. 
 
 t Klein’s Herpetalogia, p. 66. 
 
 K 
 
66 
 
 to find Leeches propagate. F rom Avhat par- 
 ticnlar cause this arises, it would be difficult 
 to determine; although it may be in all 
 probability tlie want of their proper nidus, 
 tl'.e bottom or sides of pools. Notwilhstaiid- 
 ino’ that I^^eecbes seldom brina* forth their 
 young in confinement, they still have been 
 seen, as will be presently noticed, in actu 
 coitus. It is rather singular that many in- 
 sects which produce their young in confine- 
 ment, will not copulate in that state ; for 
 instance, the Queen Bee. The fcecundation 
 of this insect will never, according to Huber, 
 take place in the hive, although she is sur- 
 rounded by males ; but if, says this accurate 
 observer, she be allowed to escape from the 
 hive, she then mounts high in air, and there 
 the nuptial rites are celebrated.*. The fe- 
 male Ants, on the authority of several emi- 
 nent naturalists, are obliged to leave the 
 
 * See Huber’s interesting Remarks on the Impregnation 
 of the Queen Bee. 
 
67 
 
 ant-hill previous to foecimdation ; but as soon 
 as this state is accomplished, they return to 
 their nest, and are so busied in depositing 
 their eggs, that the desire of undertaking any 
 more mrial excursions is entirely suppressed. 
 Their wings, hitherto usetiil, but now only 
 an incumbrance, they soon destroy ; a fact 
 often witnessed by M. P. Huber, son of the 
 ingenious jdiysiologist above alluded to.* 
 
 That the Leech has been seen in actu 
 coitus, the following instances will, 1 trust, 
 satisfy the most scrupulous. To this state Mr. 
 Hebb, surgeon, of Worcester, has been more 
 than once a witness. The Leeches, he in- 
 forms me, were in full size and vigour ; but he 
 is acquainted with no instance of this union 
 being productive. Mr. Evans, druggist, at 
 Worcester, has also seen them in actu coitus, 
 
 * For some interesting' particulars relative to the several 
 species of Ants, I refer my reader to the recent publication 
 of M. P. Huber, entitled Recherches sur les Moeurs des 
 Fourmis, &\C. 
 
 K 2 ^ 
 
68 
 
 but only once. They were what are called 
 the Trout-Leeches (H. troctina); and he 
 remarks that a double copulation, similar to 
 what happens with the Garden-Snail, was 
 then going' forward. Of this union Mr. 
 Hebb was also a witness: he made a memo- 
 randum at the time respecting it, and informs 
 me, it is the only instance he is acquainted 
 with, of a double copulation. 
 
 A question has arisen among naturalists, 
 whether the Medicinal Leech is oviparous or 
 viviparous. But previously to our entering 
 upon this enquiry, an account will be given 
 of a few animals that lu’ing forth both eggs 
 and living young. 
 
 The Plant-Louse, particularly that species 
 found on the rose-tree, is said to be vivi- 
 parous in summer and oviparous in au- 
 tumn.* , A circumstance so extraordinary, 
 
 * Shaw’s Zoology, vol. vi. p. 168. Also, Introduction to 
 Entomology, by Kirby and Spence, vol. i. p. 174. 
 
69 
 
 as may well be supposed, excited no small 
 degree of attention. It was at first doubted ; 
 but at length Trernbley, Bonnet, Reaumur, 
 and Lyonnet, stepped forward to bear witness 
 to its truth. Of what Dr. Win. Richardson 
 has advanced on this very curious point, I 
 shall now avail myself, trusting that its in- 
 terest alone will be a sufficient apology for 
 its present introduction. This gentleman 
 states, that at the beginning of February, if 
 the weather happens to be warm, small 
 Aphides are frequently to be found upon the 
 buds of the rose-tree, which are no larger 
 than the young ones in summer, when first 
 produced. But as there were then no old 
 ones to be found, which in summer he had 
 observed to be viviparous, he was exceedingly 
 surprised, and almost induced to give credit 
 to the old doctrine of equivocal generation. 
 That the same kind of animal should at one 
 time of the year be viviparous and at another 
 time oviparous, was an opinion he could by 
 
70 
 
 no means entertain ; yet frequent observation 
 convinced him that this was really the case. 
 Those aphides, he remarks, that appear 
 early in the spring’, proceed Irom small black 
 oval eggs,* which had been deposited in 
 autumn. But what necessarily excites our 
 surprise is, that all these should be females, 
 producing about the month of April a very 
 numerous progeny, and without having in- 
 tercourse with any male insect. Five gene- 
 rations of these insects succeed each other 
 during the spring and summer months, and 
 would prove extremely destructive to vege- 
 tation, were they not now and then destroyed 
 by the artifice of a very small black Ichneu- 
 mon Fly, who darts its pointed tail into the 
 body of the aphides, and there deposits its 
 eggs, which at length producing worms, 
 destroy the aphides as food, ■f From 
 
 * These eggs, when recently excluded, are green, but 
 afterwards assume a deep black. 
 
 t Philos. Trans. Abridged, vol. xiii. p. 1"20. 
 
. 71 
 
 Bonnet, who spent so much of his time in 
 observing the habits of tliese insects, that, he 
 he is said to have almost taken up liis abode 
 with tliem, we learn, that sexual intercourse 
 takes place among the aphides only once a 
 year. He took the aphides when first pro- 
 duced, and kept each individual separate. 
 All the females brought forth young. These 
 he kept individually apart, as in the former 
 instance, and with the same result. This 
 happened even to the ninth generation. 
 
 The aphides, as already stated, are ovipa- 
 rous and viviparous in the same year ; but 
 this, Mr. Curtis observes, in his interesting 
 paper on these insects*, is not the case with 
 all of this genus ; for he remarks that the 
 Aphis Salicis, from the 24th of September to 
 to the 6th of December following, during 
 which time Fahrenheit’s thermometer was 
 as low as 29”, was constantly viviparous. 
 Other aphides, he remarks, are oviparous or 
 
 * Linn. Trans, vol. vi. p. 7S. 
 
72 
 
 viviparous according to the temperature of 
 the air to which they are exposed. In very 
 cold weather they are oviparous, for this 
 obvious reason : the eggs are capable of re- 
 sisting cold more powerfully than the young. 
 On the 22d of November he found, without 
 doors, on some auricula plants, the eggs of a 
 small green aphis, while the same species, on 
 a geranium tliat he kept within doors, pro- 
 duced young. 
 
 The common W ood-Louse ( Oniscus asel- 
 lus) is sometimes seen to produce eggs ; at 
 other times, young, perfectly formed. 
 
 Redi, in a work upon the generation of in- 
 sects (Esperienze intorno alia Generatione 
 Deg ’1 Insetti), mentions that some flies are 
 viviparous, others oviparous only ; adding, 
 that the same flies sometimes breed live 
 worms, at other times lay eggs ; and this he 
 says is determined by the greater or less heat 
 of the season. ^ 
 
 From the evidence here adduced, may not 
 
73 
 
 the conjecture be reg-arded as plausible, that 
 the Medicinal Leech is, under certain circum- 
 stances, both oviparous and viviparous ? If 
 this be admitted, it will serve to reconcile the 
 several statements, contradictory as tliey are, 
 which follow. 
 
 A scientific friend of mine, who resides in 
 the neighbourhood of Kenfig in Glamorgan- 
 shire, made several enquiries for me, during 
 the last summer, among those whose employ- 
 ment was the collecting of Leeches from the 
 very extensive sheet of water at that place, 
 relative to the habits, &c. of the Medicinal 
 Leech. From his letter, now before me, I 
 learn, that they bring forth their young alive ; 
 that the young are exceedingly small, of a 
 white colour, aud very numerous ; that they 
 assume their general colour in the course of 
 a few months ; that they are five years in 
 attaining to their full grow th ; and that the) 
 
 L 
 
T4 
 
 have been known to exist a period of at least 
 twenty years. 
 
 Mr. Baker informs me, that he received in 
 the month of July, from Thomas W ebb, a 
 leech-gal herer who resides in the Moors, 
 near Glastonbury, one hundred large Me- 
 dicinal Leeches, which were immediately 
 placed in a tin canister containing water. 
 On the following day, he was surprised to 
 find among them several small Leeclies, in 
 active motion, appearing as so many dark- 
 coloured threads. It might be supposed that 
 ova, or even young Leeches, were present, 
 without being noticed ; but this, Mr. Baker 
 contends, is unlikely, observing, that the 
 Leeches were placed in a tin canister con- 
 taining water only. 
 
 This is one of the few instances that have 
 come to my knowledge, of the Medicinal 
 Leech bringing forth its young alive ; and it 
 would have been an injustice towards Mr. 
 Baker, who is firmly of opinion that the 
 
75 
 
 Medicinal Leech is viviparous, to have 
 suppressed it. 
 
 Indeed the collected testimony of the leech- 
 gatherers amounts to this, — that the Medici- 
 nal Leech brings forth its young alive ; but on 
 their opinion we must not place too much 
 reliance, since they are by no means accurate 
 observers of Nature. 
 
 Horn also remarks, that they are viviparous, 
 and produce their young, capable of acting 
 in every respect as the parent animal. Thi«, 
 he observes, takes place in the months of 
 April and May, tlie latter end of August, and 
 in September. 
 
 Durondeau is led to the supposition of 
 their being viviparous, from the structure of 
 the womb, and the largeness of the genital 
 organs. 
 
 M. Thomas, a recent French writer, re- 
 marks, that in the vessels where Leeches are 
 confined, there are often discovered, towards 
 the end of summer, small filiform Leeches. 
 
 L 2 
 
76 
 
 Had tliese, he says, been placed in the vessel 
 at tlie same time with other Leeclies, they 
 could not have remained concealed. Desi- 
 rous of ascertaining if the Medicinal Leech 
 produced ova, this author was at some pains 
 to examine the water, each time it was 
 changed, to discover, if possible, any germ of 
 a future Leech ; but without success. If the 
 Leech, he adds, is oviparous, how can we 
 reconcile the fact of filiform Leeches being 
 found in a vessel, the water of which was 
 renewed every day ? — and how happens it 
 that we cannot find the ova in water which 
 has been preserved for a very long period 
 Not having ever seen these ova, lie pro- 
 nounces it as his opinion, that the Medicinal 
 Leech is viviparous.* 
 
 Linnaeus, it has been asserted, embraced a 
 similar opinion. This celebrated naturalist, 
 it IS true, said that the H. octoculdtci (H. 
 vulgaris) was viviparous, but never so 
 
 * Memoires sur les Sangsues, p. 107. 
 
77 
 
 expressed himself in regard to the H. mtdici- 
 nalist. When Bergmann observed that the 
 coccus oquaticus was the ovum or egg of 
 this animal (H. vulgaris) producing from 
 one to ten young, Linnmus, who had for- 
 merly denied tins fact, was struck witli asto- 
 nishment ; and when the proofs in support of 
 it were given him, vidi et ohstupui \seve the 
 words he is said to have uttered, and which, 
 in giving his approhalion, he wrote down at 
 the foot of the memoir.* 
 
 With respect to my own opinion, I believe 
 tlie Medicinal Leech to be oviparous. The 
 ova it produces are, I think, but few in num- 
 ber, and are either deposited in tlie bottom or 
 banks of pools, or agglutinated to the roots 
 of aquatic plants. About the latter end of 
 April, in changing the water in which were 
 a few Medicinal Leeches, I observed an 
 ovum attached to the side of the glass-vessel. 
 This ovum was preserved many months, but 
 
 * Dictionnalre Naturdle, 1791 ; art. Sangsue. 
 
78 
 
 it proved unproductive ; which was the case, 
 as before remarked, with the ova of the H. 
 vulgaris, produced in cfmfinemeiit. In its 
 fig'ure, it resembled the ova of the IL vulga- 
 ris, but was in size much larger, and corres- 
 ponded to the character given by M. Virey ; 
 who states that the eggs of the Medicinal 
 Ijccch are, in shape, semi-oval, have a 
 shell or crust of a brown colour, and are 
 transparent.* 
 
 In one of our modern Pharmacopoeias, 
 the Leech is also said to be oviparous, the 
 ova being deposited in one involucre or cover- 
 ing, near the margin of pools, and hatched 
 by the heat of the Sun.^f* I should suppose, 
 I’rom a note subjoined, that this information 
 was derived from Mr. James Dickson, of 
 Covent-Garden, who is stated to be well ac- 
 quainted with the natural liabits and oeco- 
 nomy of the Leech. I wrote, in the early 
 
 * Journal de Physique, tom. iv. p. 409. 
 t Lond. Pharm. by A. T. Thomson j art. Leech. 
 
79 
 
 part of the spring of this year, to that gentle- 
 man, soliciting further information; but J 
 regret to observe that I received no answer. 
 
 Mr. Hebb lias seen, in the month of May, 
 protruding from the female organ of genera- 
 tion in large Leeches, a white opaque oval 
 substance, which he conceives to be an o^alm. 
 That the contents of these ova are not evol- 
 ^ ed may, he says, depend upon tiie absence 
 of that Just temperature and direct influence 
 of the Sun wliicli may be necessary to pro- 
 duce such evolution.* 
 
 The Leech is very tenacious of life. To 
 the experiments already mentioned, of its 
 living several months without either the head 
 or the tail, I shall now add those, in which it 
 has been subjected to the Air-Pump, and to 
 the influence of several kinds of gas. 
 
 A Leech was put into a glass vessel con- 
 taisiing a little water, and placed under an 
 
 * Encyclop. Lond. art. Hlriuh. 
 
80 
 
 air-pump. The air was then exhausted. 
 The Leech was kept under the exhausted 
 receiver five days, without suftering much 
 inconvenience, being nearly as lively on tlie 
 admission of fresh air, as when first subjected 
 to the experiment. 
 
 Durondeau kej)t eight Leeches under an 
 exhausted receiver for eight days. All this 
 time, he says, they suffered very little from 
 their confinement. The same writer found 
 that a single Leech, subjected to a similar ex- 
 periment, lived until the twenty-third day.* 
 The following animals were put into sepa- 
 rate glass vessels, each filled with a pound- 
 weight of distilled water, and the vessel in- 
 verted upon (piicksilver, viz. one Gold-Fish, 
 one F rog, two Leeches, and one fresh-water 
 Muscle. The Frog died on the third day, 
 the Fish on the fifth, the Leeches on the 
 eighth, and the fresh-water Muscle on the 
 thirteenth, "f- 
 
 * Journal de I’hysiquej \7S>9 , ; p. 289. 
 t Philos. Trans. 1805 j pt. i. p. 16. 
 
81 
 
 The Leech will live for a considerable 
 period in the ditferent kinds of gas. I found 
 them to live in a glass vessel containing 
 
 Three cubic inches of Hydrogen Gas, ... .2 days 12 hours. 
 
 Carbonic Acid Gas, 0 
 Nitrogen Gas, .... 8 
 Atmospheric Air, . . 10 
 Oxygen Gas, .... 12 
 Water strongly im-.. 
 pregnated with f 
 Carbonic Acid 
 Gas, . . 
 
 Olive-Oil, 
 
 Spring-lVater, the 'v 
 vessel being well \ 
 corked, J 
 
 ci.lj 
 
 0 
 
 16 
 
 I shall now cite one or two experiments 
 made by Bibiena. Three Leeches were 
 placed in a tin case well closed, which was 
 covered with a quantity of snow, into which 
 were thrown some handfuls of common salt. 
 In two hours the Leeches were so hardened, 
 that neither the effect of a mild heat, nor that 
 of water at a moderate temperature, could 
 produce any sign of life in them. This 
 
 iM 
 
82 
 
 experiment proving fatal, Bibiena repeated 
 it, surroiincling' the tin case with snow only. 
 In four liours the Leeches appeared a little 
 contracted, but not at all frozen ; and on 
 being* thrown into pure water, soon resumed 
 their usual activity. 
 
 We shall now bring* the Natural History 
 of this very singular animal to a close, by 
 offering a few observations on the duration 
 of its life. 
 
 The Leech, it appears, has lived in con- 
 finement eight years. I learn that a medical 
 practitioner at Bridport once preserved two 
 Leeches alive during this period ; and that 
 three or four were lately in the possession of 
 a gentleman of Glastonbury, who had then 
 kept them for five years. 
 
 These gentlemen, it is probable, had the 
 Leeclies when fully grown ; and the time 
 before they could arrive to this state being 
 considered with the time they were kept in 
 confinement, we have the strongest reason for 
 
83 
 
 believing that the Leech will live in its na- 
 tive waters, where it can always meet with 
 an abundant supply of food, a period of at 
 least twenty years. 
 
 The following instances of the extreme 
 slowness of its growth, cannot but be ad- 
 mitted as valid proof of its being long-lived, 
 conformably to the general law, that the 
 longer the time an animal takes in arriving to 
 maturity, the greater is the duration of its life. 
 
 Mr. Hebb subjected to the balance, in 
 July 1808, the smallest Leech he ever saw, 
 and found it to weigh half a grain. It died, 
 owing to severe frost, the December follow- 
 ing, but had acquired no additional weight.* 
 
 M. Thomas placed in a bottle, four young 
 filiform Leeches. Two montlis elapsed before 
 there was even a slight increase ; their bo- 
 dies were still small at the end of the ninth 
 month.'f- 
 
 * Encyc. Lond. j art, Hirudo. 
 t Memoires sur les Sangsues, p. 121. 
 
 M 2 
 
84 
 
 We therefore necessarily arrive at the 
 conelusion, that the Leech is a long-lived 
 animal ; but to determine with precision the 
 exact number of years, is a point to which, 
 from our present limited information,' we 
 cannot possibly attain. 
 

 
 y>/ 
 
SECTION THE THIRD. 
 
 The Anatomical Structure of the Leech. 
 
 In this section we shall first treat of 
 the external structure, then of the organs of 
 the senses and the respiratojy organs, and 
 lastly of the internal structure, which will be 
 found to merit our notice on account of its 
 great singularity.* 
 
 * As the references will only apply to the annexed outline, 
 we shall here give an explanation of the Frontispiece. 
 
 Fig. 1 
 
 Represents the internal structure of the Leech, slightly 
 magnified. At the superior part we notice the piercers, im- 
 properly called the teeth, and the male and female organs of 
 generation 5 at the inferior parts, the two last long cells or 
 stomachs, and the intestine. The abdominal blood-vessel is 
 seen taking a direction from the mouth to the anus, forming 
 several diamond- shaped expansions in its course. We find 
 on each side of this vessel, the cells or stomachs ranged in 
 
86 
 
 THE EXTERNAL STRUCTURE, 
 
 The body of the Leech is elongated, 
 round, more or less flattened, tapering to- 
 wards the extremities, and composed, after 
 the manner of the Earth-Worm, of a number 
 of rings. 
 
 The mouth, or that portion formed by the 
 upper and lower lips, usually presents a cir- 
 cular or rather a horse-shoe shape, and is 
 employed by the Leech as a sucker, to attach 
 itself to surrounding bodies. 
 
 At the anal extremity is another sucker, 
 
 regular order. To the surface of each is attached a small 
 oval-shaped body, forming a connexion, the one with the 
 other by means of a tortuous tube. 
 
 Fig. 2 
 
 Represents, under a highly magnified form, the body of 
 the male generative organ, with the penis hanging from its 
 sheath. The uterus with the ovaria and the testes. 
 
 Fig. 3 
 
 Represents a dried preparation, shewing a few of the eells 
 distended with common shot, and a portion of the intestine 
 in which a slip of wood has been inserted. 
 
87 
 
 broad and circular, answering the same 
 intention. 
 
 There are two openings in the belly, 
 termed generative. 
 
 There is also an opening at the lower 
 part of the back, termed the anus. 
 
 The body of the Leech, in a state of rest, 
 is of an arched form, and about an inch or 
 an inch and a half in length ; but when in 
 motion, may be extended to four, five, or 
 even six inches. 
 
 In regard to the number of rings or an- 
 nular muscles with which the body is fur- 
 nished, we are told that it increases with the 
 age of the Leech. This is, however, incor- 
 rect ; for I have counted, in a very young 
 Leech, as many rings as we are accustomed 
 to meet with in an old one of the largest size 
 — usually about one hundred. It therefore 
 appears, that as the age of the animal in- 
 creases, there is an augmentation of the rings 
 
88 
 
 in size only, and not in number. On the 
 most prominent part of each ring, there is a 
 row of minute tubercles. 
 
 The mouth is, as before noticed, of a cir- 
 cular or horse-shoe form, but from the great 
 extent of motion the lips possess, may be 
 made to assume whatever figure tlie Leech 
 finds most convenient. The external surface 
 of the mouth is of a dark grey, and the in- 
 ternal of a light grey colour. The upper lip 
 is lightly bent downward, having something 
 like a cleft in the middle. The lower lip is 
 bent inward, and like the upper lip, is in 
 form semicircular. When these lips are 
 attached to any foreign body, the strong 
 muscular apparatus in the upper part of the 
 oesophagus is brouglit into action, and by 
 enabling the Leech to form a vacuum, ren- 
 ders its attachment the more secure. 
 
 The sucker at the superior extremity, or 
 what properly speaking constitutes the mouth, 
 consists of several fasciculi of muscular fibres. 
 
89 
 
 The sucker at the inferior extremity, con- 
 sists also of an assemblage of muscular fibres. 
 Some pass from a central point towards the 
 circumference, whilst others interlace these 
 and dispose themselves circularly. 
 
 The Jirst foi'amen, or opening in the belly 
 termed generative, is round and small, situ- 
 ated at about half an inch from the lower lip. 
 From this foramen the penis issues. The 
 Ancients entertained the idea of its being 
 serviceable to the Leech for breathing. At 
 this opinion I feel little surprise, having never 
 witnessed the penis hanging from its sheath 
 in the living Leech, although in the dead 
 Leech this is so frequent an occurrence, that 
 it cannot, I should think, have escaped the 
 notice of the most cursory observer. 
 
 At a little more than a quarter of an inch 
 below this first foramen, or at the distance of 
 five rings, we find a second foramen, termed 
 the vagina. This leads to the uterus, and is 
 seldom seen unless closely inspected. 
 
 N 
 
90 
 
 Tile foramen termed the anus is situated 
 on the back, a little above the circular sucker 
 terminating the lower extremity. This fo- 
 ramen appears to have been but little under- 
 stood. Morand denies its existence, positively 
 asserting that the Leech has no opening 
 which can supply the place of an anus,* no- 
 thing passing off' but the glutinous matter so 
 generally distributed over the surface. -f 
 Dumeril steps forward in support of this 
 idea, ^ which I am surprised to find is also 
 countenanced by the justly celebrated John 
 Hunter; who, in his postscript to the descrip- 
 tion of a new marine animal (Amphitrite 
 Volutacornis) brought from Barbadoes by 
 
 * This idea may probably have been derived from the fol- 
 lowing passage Jn Pliny; “ Est animal, infixo semper san- 
 guini capite vif^fe, atque ita intumescens, imum animalium 
 cui cibi non si^exitus : dehiscitque nimia satietate, alimento 
 ipso moriens.” — Hist. Nat. tom. 1, p. 611. 
 
 t Memoires de 1’ Academic Royale des Sciences, 1739 ; 
 p. 2bl. 
 
 X Zoologie Anatique, p. ^98. 
 
91 
 
 Mr. (now Sir) Everard Home, says, “ It is 
 very singular that in the Leech, Polypi, &c. 
 where no inconvenience can arise from ha- 
 ving an anus, there is not one ; while in this 
 animal, where it would seem to be attended 
 with many, we find one ; but there being no 
 anus in the Leech, Polypi, &c. may depend 
 upon some circumstance in the animal oeco- 
 nomy which we are not at present fully 
 acquainted with.”* 
 
 These writers, and others who have impli- 
 citly followed them, appear to have taken 
 little or no trouble to ascertain how far their 
 assertions were well or ill founded. Had this 
 been the case, the error would, I am well 
 persuaded, long since have been discontinued. 
 Indeed a single dissection of the Leech would 
 have shewn them upon what a slight foun- 
 dation their remarks had been built. 
 
 Cuvier, wliose observations are for the most 
 part drawn from what he had himself seen, 
 
 * Phil. Trans. Abridged, vol. xvi. p. 5. 
 
 N 2 
 
92 
 
 remarks that the Leech has an anus, but so 
 small as to have been frequently overlooked ; 
 hence the belief has gained ground, of its 
 non-existence.* 
 
 Poupart, in describing the Intestine of the 
 Leech, under whicli name he includes what 
 I have thought fit to distinguish by the term 
 Alimentary Canals says that it proceeds in a 
 straight line from the mouth to the anus (en 
 ligne droite depuis la bouche jusques a 
 I’anus), and is of the thickness of a common 
 quill.-f He makes no other mention of the 
 anus than in this general way ; but this is 
 sufficient to convince us he was thoroughly 
 aware of its existence. 
 
 Virey and Thomas, two respectable French 
 writers, and Blumenbach, the celebrated Ger- 
 man physiologist, have made observations to 
 the same effect. 
 
 * Lecon’s d’Anatomie Comparfee, tom. iv. p. 141. 
 t Journal des Scavans, 1697 } p. 538. 
 
 I Menioire sur la classe des Vers, par J. J. Virey j Journal 
 
93 
 
 ‘‘ The readiness,” Sir Everard Home re- 
 marks, “ which the Leech possesses of dis- 
 gorging- itself, has led into the general mistake 
 of its having no second opening by which the 
 contents of the stomach may be evacuated.”* 
 
 I have been thus minute in giving the 
 opinions of various authors concerning this 
 foramen, in consequence of my finding its 
 existence still denied, in publications of recent 
 date ; but if any further proof be required, I 
 have only to observe, that I have several 
 times injected a fluid, from the mouth of the 
 Leech, so as to flow out in a continued small 
 stream through this very opening. And to 
 make it the more satisfactory, I have reversed 
 the experiment, by emjjloying a glass tube, 
 
 de Physique, tom. iv. p. 438. Mem. sur les Sangsues, 
 par M, Thomas, p. 49. Comparative Anatomy by Blumen- 
 bach, translated from the original German by Lawrence, 
 p. 176. 
 
 * Home’s Lectures on Comparative Anatomy, p. 366. 
 
u 
 
 drawn out to a very slender point, and 
 inserted into this identical foramen. Through 
 
 o 
 
 this I have forced an injection, and thus 
 filled the whole of the internal cavity. 
 
 This foramen or anus lies immediately 
 above the rim of the circular sucker at the 
 inferior extremity, and is large enough to 
 admit a common-sized pin. In the dead 
 Leech it may be discovered with the utmost 
 readiness. This foramen is so much larger 
 in the H. sanguisuga than in the H, medici- 
 nalis or H. troctina (a wise provision of 
 Nature, for allowing a quick removal of the 
 foecal matter so soon generated in this species, 
 on account of its great digestive powers), 
 that by slightly pressing the lower part of the 
 body, foeculent matter will almost to a cer- 
 tainty escape, and thus remove every doubt 
 of its existence. 
 
95 
 
 THE ORGANS OF THE SENSES. 
 
 Before we enter upon the consideration of 
 the internal structure of the Leech, I have 
 thought fit to notice what appertains to the 
 organs of sense ; and first of 
 
 The Organ of Vision. 
 
 The eyes of the H. medicinalis, H. san- 
 guisuga, H. troctina, and II. nigra, are ten 
 in number, ranged under tlie form of a 
 crescent at the pointed extremity on the 
 back part of the head. 
 
 The two eyes on each side terminating the 
 border of the crescent, are placed at greater 
 distances from each other than the rest. All 
 the eyes under the field of the microscope, 
 appear as tubercles jutting forth from the 
 skin. They are of a deep black, and when 
 moistened, have a fine glossy lustre. I must 
 here observe, that uhen the head is much 
 
96 
 
 Gontractecl, they cannot be seen. It is neces* 
 sary to be acquainted witli tliis circumstance, 
 or we might conclude, from an imperfect in- 
 spection, that they are wanting. Besides, 
 the head being itself of a dark colour, they 
 are likely to escape notice ; hence the inspec- 
 tion should take place under the favourable 
 circumstance of a strong light. When the 
 head is fully expanded, and the lips firmly 
 applied to any surrounding body, the eyes 
 may be readily observed; and should the 
 Leech have just quitted the water, they 
 become, from the bright and vitreous ap- 
 pearance they then assume, evident to the 
 naked eye.* 
 
 The Organ of Touch. 
 
 The organ of feeling, or of touch, resides 
 
 * Those who wish to have preparations of these organs, 
 may readily form them, by cutting off the head of the Leech, 
 and subjecting it, between two strong plates of glass, to con- 
 tinued pressure. In this way I have made dried preparations 
 of tlie organ of vision in tlie different species of Leeches that 
 have fallen under my notice. 
 
97 
 
 in the lips, and according to Cuvier, even in 
 the disk tliat terminates the lovrer extremity. 
 
 The Organ of Taste. 
 
 In considering the avidity of the Leech for 
 blood, vve are quickly sensible of its possessing 
 an organ of taste, which we find situated in 
 the upper part of the oesophagus, and com- 
 posed of an assemblage of nervous fibrillm. 
 
 The Organ of Hearing. 
 
 The closest anatomical inspection does not 
 advance us a single step in determining the 
 situation of this organ ; but there can be no 
 doubt that it is granted to the Leech, in com- 
 mon with the numerous tribe of animated 
 beings.^ 
 
 * It may not be foreign to our subject, to remark that 
 the organ of hearing has not been yet discovered in the 
 common Bee, although we are furnished with sufficient 
 proof of its existence j for when, as Huber informs us, the 
 imprisoned Queen Bees desire their liberty, they emit those 
 
 O 
 
98 
 
 The Organ of Smell. 
 
 If the Leech breathes, as I am firmly of 
 opinion it does, by pimcta respiratoria, or 
 breathing-holes, the organ of smelling will 
 be there found to exist, in accordance with 
 the idea of those naturalists, who suppose the 
 stigmata of insects to be the true organs of 
 smelL 
 
 THE RESPIRATORY ORGANS. 
 
 We now come to the respiratory organs, 
 regarding which there are two opinions ; 
 one, tliat the Leech breathes by the mouth ; 
 the other, by stigmata or breathing-holes. 
 
 sounds which, to the common working-bees, indicate this 
 wish ; who in consequence destroy the cells, thus favouring 
 the escape of the royal recluse. The noise or humming made 
 by the Female or Queen Bee, just as the Bees are going out 
 to swarm, is nothing more, says Swammerdam, than an 
 expression of joy, at the excursion she is about to make 5 
 and this is doubtless heard by, and animates, the whole 
 group. 
 
£9 
 
 Those who embrace the former opinion, re= 
 tain it with the more confidence, from know- 
 ing that a Leech will live several days in oil ; 
 this fluid proving destructive, if poured over 
 the body of those animals that breathe by 
 gpiracula. To determine how long a Leech 
 would live in oil, I subjected one to the 
 following experiment. 
 
 In a small phial, filled with the best olive- 
 oil, I placed an exceedingly lively Leech. It 
 at first appeared very little incommoded by 
 its imprisonment, but in a few hours was seen 
 to have that hurried or waving motion which 
 we frequently observe among Leeches when 
 there is any sudden change in the atmos- 
 phere, evidently with a view of extricating 
 itself from its situation, which was then be- 
 coming unpleasant. This waving motion 
 was continued at intervals the whole of the 
 first day. During the early part of the 
 second day, the Leech kept firmly attached, 
 by both of its extremities, to the sides of the 
 
 U AJ 
 
100 
 
 vessel, and remained motionless. In forty 
 hours from the commencement of the experi- 
 ment, it became languid, relinquished its 
 hold, and shortly afterward died. 
 
 That the Leech should thus live two days 
 in oil, is, we cannot but admit, in favour of 
 the opinion of its breathing by the mouth ; 
 and to this opinion I might lean, had I not 
 ascertained by experiment, that a Leech will 
 live as long a period, that is, two days, with 
 a liffature drawn around its head so ti^ht 
 as to preclude the possibility of its receiving 
 air by this aperture. 
 
 The Earth-Worm, it is well known, 
 breathes by spiracula; and yet Redi remarks 
 that he once kept two immersed in oil for 
 twenty-four hours, placing them afterward 
 in a vessel with moistened earth. The one 
 survived the experiment three, and the 
 other six days. “ In duo vasa oleo plena 
 immersi crassos duos Lumbricos, qui ibi vi- 
 ginti quatuor boras manserunt, licet torpidis- 
 
101 
 
 simi viderentur. Eos extra oleum edux 
 liberosqiie reliqiii in vase terra hiimida pleno^ 
 iibi unus tertio die interiit, alter vero ad sex- 
 tiira usque diem vixit, quamvis semper tor- 
 pidus, vix(|ue vivus videretur. Unde con- 
 cludere licet, oleum quantumvis lumbricis 
 noxium sit, iis tamen non esse potentissi- 
 mumque venenum, ut revera solet esse 
 permultis insectorum generibus, siciit Muscis, 
 Vespis, Apibus, Limacibus nudis, Bombvci- 
 bus, Sanguisugis, permultisque aliis liujus- 
 modi animalculorum generibus.”* From this 
 passage it appears that Earth-Worms are 
 less affected by being placed in oil than 
 Leeches. This, thongli not strictly correct, 
 may yet approximate to the truth ; and so far 
 the argument, on which great stress has been 
 laid, that Leeches do not respire by spira- 
 cula, on account of their living in oil, is 
 rendered in some degree inconclusive. 
 
 To determine, however, the accuracy of 
 
 * De Viventibus intra Viventia, p. 153, 
 
102 
 
 this experiment, and how far it may be relied 
 on, I placed three middle-sized Earth-Worms 
 in the phial in wliich I before imprisoned the 
 Leech, removing them at the several periods 
 of twelve, twenty-four, and thirty-six hours, 
 and transferring them to a vesseh filled with 
 humid earth. In a short time, symptoms 
 of vitality were evident in each, particularly 
 toward the extremities ; which excited an 
 idea of their speedy recovery. In this respect 
 I was deceived: that which had been im- 
 mersed only twelve liours survived the rest, 
 but in a state scarcely to be called living, 
 about two days. 
 
 The membranous sacs or bladder-like 
 bodies which M. Thomas conceives are 
 tiie true respiratory organs in Leeches, 
 and which occur on every fifth ring, 
 are, in fact, the bodies that contain the 
 ui'ictuous liuid for lubricating the surface, 
 and will fall under our consideration in a 
 
103 
 
 subsequent part of this section, under the 
 name of lateral vesicles. In justice, however, 
 to this author, I transcribe the passage in 
 which these bodies are alluded to. “ Bientot, 
 dans line dissection plus attentive, je re- 
 marquai qu’il y avoit a certaines distances, 
 sur les deux cotes du corps de la Sangsue, 
 des especes de sacs nieinbraneux, transparens, 
 en forme de vessie, qui etoient renfles, et ne 
 paroissoient contenir que de Pair. J’observai 
 la distribution qu’ils presentoient, et Je recon- 
 nus qu’ils etoient places d’une maiiiere regu- 
 liere sur les deux cotes de I’animal. Ils 
 - existent depuis la bouche Jusqu’a I’origine 
 du disque, et sont assez rapproches I’un de 
 1 ’autre. Je~^me rappelai alors que j’avois vu, 
 a la peau, des trous plus grands que les au- 
 tres, d’ou il m’avoit semble que s’echappoient 
 des bulles d’air, et d’ou j’avois vu sortir des 
 gouttes d’un liquide blanchatre. Je les ex- 
 aminai de nouveau, et je trouvai, comme je 
 I’ai deja dit, qu’il y avoit entre chacun de ces 
 
104 
 
 trous I’iiitervalle de cinq anneaux. II etoit 
 probable que c’etoit comme autant d’ouver- 
 tures qui conduisoient aux corps en question. 
 J’y fis en efFet passer ime soie de cochon, et 
 j’arrivai directeinent dans ces corps.”* These 
 bodies, he observes, in conclusion, are the 
 true organs of respiration in Leeches. 
 
 Cuvier, in describing the lateral blood- 
 vessels of the Leech, has thus expressed him- 
 self: “ II y a de chaque cote, un gros 
 vaisseau longitudinal, (pii communique avec 
 son ojjpose, par beaucoup de vaisseaux trans- 
 verses, formant deux reseaux a mailles rhom- 
 boidales dont Tun du cote du ventre. II 
 faut que les rameaux de ce reseau, qui s'epa- 
 noLiissent a la surface de la peau, servent a la 
 respiration de I’animal, car il n’a point d’au- 
 tre organne, pour cette function. ’’"f- 
 
 We may add, in support of the Leech 
 
 * Meinoires sur les Sangsues, p. 70. 
 
 t Lecon’s d’Anatomie Coinpar^c j tom. iv. p.413. 
 
105 
 
 hreathing by spiracula, that small globules 
 of air are frequently seen to escape from the 
 surface of the body, when the Leech is about 
 to cast off its scarf-skin ; which operation is 
 greatly facilitated by the passage of a column 
 of air between the body and epidermis. 
 
 From a review of these statements, we are 
 authorised, I think, in concluding that the 
 Leech breathes by spiracula or breathing- 
 holes, and not by the mouth. 
 
 THE INTERNAL STRUCTURE. 
 
 Besides the epidermis or outer covering, 
 the coats proper to the Leech are the cutisy 
 the muscular coat, and the meinbranous coat, 
 with intervening cellular substance. 
 
 If an incision be made on the belly of 
 the Leech, and carried in a straight line 
 from the mouth to the anus, but not so deep 
 
 p 
 
106 
 
 as to penetrate into the alimentary canal, we 
 bring’ into view — 
 
 The three piercers (a), incorrectly deno- 
 minated teeth. 
 
 The nervous mass surrounding the oeso- 
 phagus, or what constitutes the brain. 
 
 The abdominal blood-vessel (cc) passing 
 fi’om the head to the tail, having several 
 diamond-shaped expansions in its course. 
 
 The lateral blood-vessels (kk). 
 
 The male organ of generation (d). 
 
 The female organ of getieration (f). 
 
 The testes (e). 
 
 The abdominal vesicles (gg) lying on the 
 surface of the several cells or stomachs. 
 
 The lateral vesicles (ii) containing the 
 unctuous fluid for lubricatirig the surface. 
 
 Continuing the incision into the internal 
 cavity, we meet with — 
 
 The oesophagus. 
 
107 
 
 The stomachy divided into several com- 
 partments or cells. 
 
 The alimentary canal. 
 
 The intestine (m). 
 
 The Epidermis. 
 
 The epidermis or outer covering' of the 
 Leech, is a thin fibrous reticulated mem- 
 brane. It is thrown off from the body every 
 four or five days, and often seen floating in 
 the water under the fonn of a little ring. 
 
 The Cutis. 
 
 The cutis, on an external view, seems to 
 be a dense and firm membrane ; but inter- 
 nally it presents a flocculent appearance. 
 Its texture is spongy. It is firmly attached 
 to the muscular coat, lying beneath, par- 
 ticularly in the intervening space of each 
 ring, where it loses much of its flocculent 
 appearance. 
 
 p 2 
 
108 
 
 The Muscular Coat. 
 
 The muscular coat, which is of an ash- 
 grey colour, consists of two layers of fibres, 
 disposed circularly and longitudinally. The 
 longitudinal layer (h) is very conspicuous. 
 These two sets of fibres interlace each other, 
 and cannot, without deranging their struc- 
 ture, be separated. They possess great 
 strength and elasticity, enabling the Leech 
 to perform with facility all its varied move- 
 ments. 
 
 The Membranous Coat. 
 
 The membranous coat is extremely deli- 
 cate. It forms a lining to the whole internal 
 cavity, and viewed by the microscope, appears 
 like fine lace. 
 
 The Piercers. 
 
 The piercers (a), improperly termed teeth, 
 have a rounded form, with sharp cutting 
 edges. They are three in number, and 
 
109 
 
 cartilaginous. They rest on small eminences, 
 and are so placed in regard to each other, as 
 to meet in a centre under equal angles. They 
 are confined in their relative situation by a 
 strong circular ligament, which surrounds 
 the oesophagus. 
 
 The wound which the Leech inflicts has 
 been compared in figure to that occasioned 
 by a three-edged sword or dagger, such as is 
 called by the Italians estocado ; and is attri- 
 buted by Poupart, not to the introduction of 
 the piercers, but to the force of suction alone. 
 “ Lors que la Sangsue,” he says, “ aplique la 
 bouche sur la chair de quelque animal, tons 
 ces muscles* venant a se contracter, elle I’a 
 Slice avec taut de violence et d’avidite, 
 qu’elle la fait entrer en forme de petit mame- 
 lon jusques dans sa gorge : de sorte que tout 
 I’efort de la suction se terminant dans un 
 
 * Alluding to the several bands of muscular fibres in the 
 throat. 
 
no 
 
 I'ort petit espace, il faut necessairement que 
 la chair se creve dans cet endroit: car il 
 ne faut pas croire que la Sangsue la perce 
 avec uii eguillon, come Tout ecrit plusieurs 
 auteurs.”* 
 
 With this opinion of Poupart, I was 
 at one time strongly inclined to coincide, 
 supposing it highly improbable that the 
 wound could be produced by other means, 
 more particularly as the piercers were only 
 cartilaginous, and hence, one would imagine, 
 little likely to form a puncture in a substance 
 so dense as the skin. Touching upon 
 this point in conversation with my highly 
 valued friend Mr. William Swayne, we were 
 anxious to ascertain whether the wound was 
 produced by suction alone, or by the inser- 
 tion of the piercers. Being provided with a 
 middle-sized Leech, he applied it to his arm, 
 and allowed it to remain affixed four or five 
 minutes. The head was then separated, 
 
 * Journal des Scavans, 1697 ; p. 537- 
 
Ill 
 
 with a quick cut of the scissars, from the 
 rest of the body, and as near as possible to 
 the place of attachment. Notwithstanding 
 this separation, the head continued strongly 
 affixed, and the blood was pumped up for 
 some minutes, owing to the strong muscular 
 action that still centered in the oesophagus. 
 The edge of a penknife was then applied to 
 the lips, and they were carefully raised ; 
 when the piercers were found to be buried 
 in the skin. This experiment was repeated, 
 and with a like result. It therefore appears, 
 that not only is the wound produced by the 
 insertion of these piercers, but the piercers 
 remain lodged in the skin during the whole 
 of the operation. To penetrate the skin is, 
 to the Leech, an office of some labour : it is 
 not effected by merely thrusting forward the 
 pierces with any force, but by constantly 
 (aided by the power of suction which keeps 
 the skin on the stretch) moving them back- 
 ward and forward, scratching as it were the 
 
112 
 
 cutis each time, and thus by degrees burying 
 them in the skin. That the wound is not 
 produced all at once, may be also fairly 
 inferred, from the gnawing pain that con- 
 tinues for two or three minutes after the 
 Leech has commenced its operations. 
 
 Whilst the Leech is in the act of suck- 
 ing, the piercers, I should have before re- 
 marked, at that time stiffened, are in mo- 
 tion, being carried from side to side in an 
 oblique direction. Their action may be seen 
 by presenting to the Leech a coagulum of 
 blood, and when the Leech is in the act of 
 suction, cautiously removing it. For a few 
 seconds it appears unconscious of its removal, 
 which presents a fair opportunity of observing 
 the oscillatory movement of each piercer. 
 
 The Nervous Mass or Brain. 
 
 The brain of the Leech is said to consist of 
 a single nerve. This was the opinion of 
 Mr. John Hunter; who, in his valuable 
 
113 
 
 preparations of the brain of different animals, 
 from their more simple state of organization 
 to their more complex state, placed the brain 
 of the Leech, consisting of a nerve only, at 
 one end of the scale, and the brain of man at 
 the other. Poupart and Cuvier, in describing 
 the brain, speak also of this nerve ; but it is 
 sufficiently manifest, from their description, 
 that they allude to the abdominal blood- 
 vessel. 
 
 In those animals in which we vainly en- 
 deavour to discover a brain, the first ganglion 
 that presents itself, or forms a collar to the 
 (Esophagus, is mentioned as not only supply- 
 ing its place, but actually receiving its name. 
 Thus, in the Water-Scorpion (Nepa cine- 
 rea), the nervous system consists of three 
 ganglia ; the first of which supplies the place 
 of the brain.* And in the Sea-Mouse (Aph~ 
 rodita aculeata) we find a large nervous 
 
 * Lecon’s d'Anatoniie Comparfee, tom. ii. p. 346. 
 Q 
 
114 
 
 ganglion, situated above the mouth, which is 
 stated to be the brain.* 
 
 Surrounding the oesophagirs of the Leech, 
 we observe a similar mass or ganglion, from 
 which issue nervous filaments, to the diffe- 
 rent parts of the body. This mass we shall 
 therefore, according to established usage, 
 denominate the Brain. From the brain 
 proceed laterally two nerves, which go for- 
 ward to the tail, here and there expanding in 
 their course. To these must be added a 
 central nerve, or that which occupies the 
 middle line of the abdomen. As it regards 
 this nerve, we notice this singularity, that it 
 occupies the interior of the abdominal blood- 
 vessel, or in other words, that this vessel forms 
 its envelope. This nerve has several expan- 
 sions or ganglia in its course, which assume 
 the shape of a diamond, answering to the 
 figure so frequently repeated in the abdominal 
 blood-vessel. 
 
 * Lccon’s d’Anatomie Comparbe, tom. ii p. 353. 
 
115 
 
 The Blood-Vessels. 
 
 The vessels of the Leech, like those of the 
 Earth-Worm and others in the same class, 
 contain red blood. The abdominal blood- 
 vessel (cc) which has been hitherto con- 
 sidered as the nerve or brain of the Leech, 
 proceeds in a straight line from the month to 
 the tail, and forms several expansions in its 
 course, where it assumes the figure of a dia- 
 mond. The first of these appearances is met 
 with, a little below the lip ; the second, at the 
 commencement ; the third, at the middle ; 
 and the fourth, at the termination of the oeso- 
 phagus. The fifth is invariably seen upon 
 the bag of the male generative organ. The 
 rest observe regular distance, and terminate 
 close to the disk at the inferior extremity. 
 M. Thomas speaks of this vessel as a mem- 
 brane between the nerve, but is unconscious 
 of its being a tube that conveys the circula- 
 ting fluid. Upon this point, however, I can 
 
 p 2 
 
116 
 
 speak decisively, having' several times seen 
 the blood circulating in it. 
 
 Besides this abdominal vessel, there are 
 two lateral blood-vessels and one dorsal 
 blood-vessel. 
 
 The lateral vessels (kk) are, when the 
 Leech is in motion, nearly straight; but when 
 the animal is at rest, they give the appear- 
 ance of a circle of festoons. The dorsal 
 vessel, as its name implies, is situated upon 
 the back, and passes in a direct line from the 
 head to the tail. 
 
 The communication between these vessels 
 is effected by a vast number of minute trans- 
 verse branches, irregularly distributed. 
 
 In all these vessels I have, in my dissections 
 of the Leech in its living state, seen a well- 
 marked systole and diastole. The pulsations 
 that occurred during the first minute were 
 ten ; the second minute, nine ; the third mi- 
 nute, eight. From this period they became 
 
nr 
 
 irregular and indistinct, and the Leech died. 
 On holding up the H. vulgaris to the light, 
 these movements may be distinctly seen even 
 with the naked eye, the pulsations being about 
 eight in a minute. I have at ditFerent times 
 placed the most transparent of the H. vulgaris 
 under the microscope, but never yet could 
 trace any central organ of the vascular sys- 
 tem. We find, however, in a paper by Uu- 
 rondeau, that the Leech (H. medicinalis) is 
 described as having a heart, which is said to 
 be a fleshy pouch, in figure conical, but irre- 
 gular ; attached to the back by large vessels, 
 but free and floating at its point.* A heart 
 answering to this description I have never 
 yet observed. 
 
 Sir Everard Home, speaking of the circu- 
 lation of the Caterpillar, remarks that the 
 blood is carried from one end of the body to 
 the other by a species of peristaltic motion, 
 in a tube, which may be either called Hear't 
 * Journal de Physique, 1782; p. 287. 
 
118 
 
 or Artery.* Tiie heart of tlie Bee, accor- 
 ding to Swammerdam, is an oblong tube, 
 liere and there dilated, extending in length 
 from one end of the body to the other and 
 in regard to figure, the heart of the Worm 
 that produces the Gad-Fly nearly represents 
 the worm itself. The heart of the Silk- 
 AVonn is said to be single, and placed in the 
 upper part of the body in the back; but 
 Malpighius, who has written on the anatomy 
 of this insect, says that it is possessed of more 
 hearts than one. He doubtless considers 
 each dilatation of the vessel as a distinct heart. 
 The abdominal blood-vessel of the Leech 
 presents also several dilatations: it therefore 
 would appear that the Leech has a heart, or 
 set of hearts, in common with other animals. 
 “ Nullum est aniinal,” says Redi, “ adeo 
 
 * Philos. Trans. 1813 ; Part i. p. 238. 
 
 f Swammerdam’s Book of Nature, translated from the 
 Dutch and Latin original edition, 1758 j Part i. p. 202. 
 
 7 Ibidem, Part ii. p. 50, 
 
119 
 
 vile, parvum, minutum, et quasi invisibile, 
 quod corde iustructum non sit : omnibus, in- 
 quam, viventium, quaecunque sint, providen- 
 tia divina cor largita est: imo et permullis 
 insectis, non unicum concessit, sed unum in 
 plurima parva corcula divisum.”* 
 
 The Male Organ o f Generation. 
 
 This organ (d), enclosed in a strong mem- 
 branous bag of a circular form flattened both 
 on its upper and lower surface, is a strong 
 elastic tube, possessing great irritability. Its 
 usual leno'th is about one inch. In the dead 
 
 o 
 
 Leech it is frequently seen hanging from its 
 sheath. 
 
 The Female Organ of Generation. 
 
 The Uterus (f) is an oblong bag, formed 
 somewhat after the manner of a bag-pipe. 
 It consists of a strong membranous coat, 
 
 * De Viventibus intra Viventia, p. 91. 
 
120 
 
 covered witli muscular fibres, and is con- 
 nected vvitii the vagina, the foramen of which 
 has been already described. It is endowed 
 with a strong peristaltic motion, which is 
 sufficiently evident in a Leech under dissec- 
 tion ; and there is attached to its posterior 
 part an oviduct, leading to the ovaria. 
 
 Eacli individual Leech, having both the 
 male and the female organ of generation, is 
 of course an hermaphrodite ; but it remains 
 a question as yet undecided, whether it is 
 capable of self-impregnation. Bibiena, who 
 was the first to notice this circumstance, ob- 
 serves that each Leech receives the embrace 
 of another, and each becomes impregnated 
 in turn. He is also of opinion that each 
 Leech, singly and without the assistance of 
 another, is capable of going through the ge- 
 nerative process. “ Primum itaque conjicio 
 hermaphroditum hunc nostrum in illis esse 
 numerandum, qui et cum aliis suae speciei 
 
121 
 
 copulari possuiit, et sibimet ipsis etiam con- 
 jimgi, patris simul matris officio fungentes.” 
 Although a double copulation takes place, yet 
 I cannot but think with Bibiena, that under 
 certain circumstances, hermaphroditic im- 
 pregnation may occur in a single Leech, 
 and more particularly if by accident it be 
 removed from any of its species. 
 
 The Testes. 
 
 On each side of the male generative organ 
 is an oblong body, containing a thick fluid, 
 in colour of a greyish white. These bodies 
 I have named the Testes (e). From their 
 appearance, they have been by some writers 
 regarded as the brain. They are situated at 
 the commencement of the first pair of cells or 
 stomachs, and are furnished with tubes to 
 convey the fluid they contain, into the 
 bag of the male generative organ. Duron- 
 deau imagines these bodies to be nothing 
 
 R 
 
122 
 
 more than fecundating vesicles.* In this 
 
 o 
 
 respect I agree with him, but not in consi- 
 dering the bag containing the penis to be, as 
 he asserts, the uterus or womb. To the penis, 
 which we lately described, he gives no name, 
 observing that it is not constant. In this, 
 however, he is much deceived ; for I have in 
 no instance missed finding it. 
 
 The Abdominal Vesicles, 
 
 Lying on the surface of the cells or sto- 
 machs, we meet with several oval bodies of 
 the size and colour of mustard-seed, which 
 from their situation and structure I term 
 Abdominal Vesicles (gg). These vesicles 
 contain the same kind of fluid as the testes, 
 to which they are connected by a tortuous 
 tube. They occur in pairs, the first of which 
 is seen within a short distance of the testes. 
 The other pairs observe regular distances 
 
 * Journal de Physique, 1782; p- 280. 
 
123 
 
 and terminate about the middle of the last 
 cells or stomachs. 
 
 The Lateral Vesicles. 
 
 The lateral vesicles (ii), as their name im- 
 plies, occupy the sides of the body, are about 
 thirty in number, and have been considered 
 by M. Thomas as the true organs of respira- 
 tion in Leeches. Sir Everard Home is also 
 of this opinion.* But as far as I have 
 myself remarked, they are not connected 
 with this function ; being, in fact, the 
 bodies that secrete or contain the unctuous 
 Iluid for lubricating the surface. The unc- 
 tuous fluid or slime, so generally diffused over 
 the body of the Leech, is by a wise provi- 
 sion of Nature well adapted to guard it from 
 
 * Vide a paper by this gentleman in the Philosophical 
 Transactions for 1815, Part II., “ On the Structure of the 
 Organs of Respiration in Animals which appear to hold an 
 intermediate Place between the Class Pisces and the Class 
 Vermes, and in two Genera of the last-mentioned Class.” 
 
 R 2 
 
124 
 
 the attacks of its enemies ; from whom it rea- 
 dily escapes on account of its great slipperi- 
 ness. This is sufficiently manifest in taking 
 a Leech in the hand for a few seconds, 
 when it covers itself with slime to such a 
 degree, that it is only with the greatest 
 difficulty retained. It also prevents water- 
 insects from attaching themselves to the 
 skin, and there depositing their eggs ; and 
 is undoubtedly of the highest importance 
 in preserving the pliability and elasticity of 
 the numerous rings, in the due extension and 
 contraction of which the locomotive power 
 of the Leech is lodged. 
 
 The (Esophagus. 
 
 The oesophagus is about a quarter of an 
 inch in length. It is narrow at its com- 
 mencement, then gradually widens, and 
 again contracts on its reaching the first pair 
 of cells or stomachs. It is furnished inter- 
 nally with several muscular longitudinal 
 
125 
 
 plicse or folds, which serve to regulate the 
 pendulum-like movements of the piercers; 
 and externally with several bands (bb), com- 
 posed of strong muscular fibres. 
 
 The Cells ot' Stomachs. 
 
 The cells or stomachs,* or more properly 
 speaking, one general stomach divided into 
 several partitions, constitute about four-fifths 
 of the body. The number of these cells is 
 stated to be twenty-four ; hence the Leech is 
 said to have twenty-four stomachs. Of these 
 cells I have never seen more than eighteen ; 
 but if we are to regard the two membranous 
 folds in each of the last long stomachs as dis- 
 tinct cells, there will then be twenty-two. 
 
 * Sir Everard Home, in his late publication on Compa- 
 rative Anatomy, gives a very correct delineation of these 
 cells (PI. LXX.), and also of the intestine. Durondeau has 
 likewise presented us with a view of these cells, in an 
 engraving accompanying his Description of the Leech, 
 in the Journal de Physique, 1785; but it is extremely 
 inaccurate. 
 
126 
 
 The shape of all these cells is semi-oval, ex- 
 cept the last, which is oblong. These are 
 considerably larger than the rest (11), and 
 terminate close to the anal extremity in a 
 blind sac. The cells are all formed by a 
 reflection of the membrane lining the inter- 
 nal cavity. 
 
 As the structure of this general stomach is 
 so remarkably singular, I beg leave to point 
 out one or two methods, by which its se- 
 veral cells or partitions may be seen to 
 advantage. 
 
 Place a Leech, fully gorged with blood, 
 in a saturated solution of corrosive sublimate 
 in water. At the expiration of a week or 
 ten days, make an incision from the belly 
 into the alimentary canal, and pick out with 
 a needle the contents of each cell. Or, fill 
 the whole of the internal cavity, using a 
 finely pointed syringe, with spirits of wine. 
 In this state, let it remain four or five days; 
 then make an incision; when the cells, from 
 
127 
 
 being corrugated, will appear very conspi- 
 cuous. Or, let the cells of a recently dead 
 Leech be filled with mercury. This me- 
 thod has the advantage over those enumer- 
 ated of shewing the precise figure of each 
 individual cell. In the Frontispiece, fig. 3, 
 these cells are represented distended with 
 shot. This has given them a round appear- 
 ance, dissimilar to their real figure, which 
 is oval. 
 
 The Alimentary Canal. 
 
 The alimentary canal, a continuation of 
 the oesophagus, is about the size of a crow- 
 quill. It has openings on each side, com- 
 municating with and corresponding to the 
 number of the cells or stomachs, and is fur- 
 nished, throughout its whole extent, with 
 membranous folds, having a small central 
 opening, which, while they answer the pur- 
 pose of valves, to prevent the return of 
 
128 
 
 alimentary matter, retain the cells in their 
 relative situation. 
 
 The Intestine. 
 
 The intestine (m) is situated between the 
 two last long cells or stomachs. It is about 
 an inch in length, generally filled with foecal 
 matter, and furnished with several plicae or 
 folds. It is confined in its situation by two 
 ligamentous bands, which run at its upper 
 part in an oblique direction. At its upper 
 orifice we find a valve which prevents the 
 return of foecal matter into the alimentary 
 cavity, and at its lower end a sphincter which 
 prevents the blood, in an over-gorged Leech, 
 from forcing its way and flowing out at the 
 anus. The diameter of the intestine is very 
 small ; but when we take into consideration 
 the extreme slowness with which the diges- 
 tive powers operate, we shall find it suffi- 
 ciently large to answer all the purposes for 
 
129 
 
 which it is intended. In the H. sanguisuga, 
 whose digestive powers are very active, tiie 
 intestine is more than double the width of 
 that of tlie H. medicinalis ; aiid the aims, 
 or that foramen in which it terminates, bears 
 also a proportionate enlargement. 
 
SECTION THE FOURTH. 
 
 The Diseases, Preservation, and Manage- 
 ment of the Leech. 
 
 .As an auxiliary remedy in removing 
 many distressing symptoms attendant upon 
 disease, the Leech stands very conspicuous, 
 and we have to regard it as rather a fortu- 
 nate occurrence, that it comes in so oppor- 
 tunely to our aid in all those cases where we 
 run some hazard in having recourse to the 
 Lancet. Its employment has been at no 
 time so extensive as at the present. To its 
 beneficial influence alone, notwithstanding 
 its occasional high price, is it now indebted 
 for having a place among the common 
 
131 
 
 routine of remedies administered in Hospital 
 practice. At the Hospitals in Birmingham, 
 from the demand being- considerable, an in- 
 dividual has been for some years enabled to 
 provide for himself and his family, by fur- 
 nishing and applying Leeches throughout 
 the wliole year at a stated price. 
 
 Indeed if this plan were more generally 
 adopted, it would save the lives of an immense 
 number of Leeches that now fall a sacrifice 
 to mismanagement, and have the effect of 
 securing to us at a moderate sum, unless in 
 very severe seasons, an abundant supply. 
 
 My friend, Mr. Estlin, surgeon of this 
 city, conceiving that a similar practice would 
 be here attended with advantage, gave a few 
 directions to a poor woman how to apply and 
 afterwards treat them ; thus laudably putting 
 her in the way of obtaining a decent liveli- 
 hood. In private families where Leeches 
 are recommended, they are frequently, after 
 being applied, thrown aside and regarded as 
 s 2 
 
132 
 
 of no further use. By employing a person 
 to apply them, the advantage to be gained 
 from their use is obtained at an equally rea- 
 sonable rate, and the Leeches are reserved 
 for some future occasion. Besides^ great 
 deception may be practised in families, in 
 regard to the Leeches they buy. This will 
 not, 1 allow, happen, if the purchase be made 
 in regular shops, where the credit of the 
 dealer is at stake, but may be occasioned by 
 some designing person selling Leeches totally 
 unfit for medical use. I shall give an in- 
 stance in point. A friend of mine, who was 
 in the almost constant habit of using Leeches 
 in his family, accidentally met a man in 
 the street, offering Leeches for sale ; who 
 assured him that they were of the pro- 
 per kind, and such as he served the doctors 
 with. The price asked being much below 
 the shop-price, my friend was induced to 
 purchase nearly a hundred ; but upon his re- 
 turn home, on shewing them to a medical 
 
133 
 
 gentleman, he was informed they were of no 
 value. 
 
 To prevent any imposition of this kind, I 
 shall state, for the benefit of my readers, 
 that unless a Leech is marked with yellow 
 rings or spots, or with variegated lines run- 
 ning the whole length of the back, it will in 
 general be found useless. 
 
 Leeches are subject to great mortality, 
 arising chiefly from three particular diseases 
 to which they are liable, and which I shall 
 now proceed to notice. 
 
 1 . An ulcer seated on various parts of the 
 body, but more generally affecting the side. 
 The part on which it is situated is usually 
 contracted. 
 
 hen this disease first manifests itself, it 
 presents only a small ulcerous speck, which 
 in the course of a few days spreads with such 
 rapidity and malignity as to destroy life. 
 
134 
 
 This ulcer is frequently tinged with blood, 
 and occasionally works a passage internally. 
 Sometimes it is of little or no depth, and of 
 no extent, appearing to be a simple abrasion 
 of the skin. Trifling, however, as this may 
 seem, it proves, as many must have witnessed, 
 abundantly destructive. 
 
 2. Another disease, of equal malignity, is, 
 when one portion of the body is narrowed 
 in its diameter, and rigid, whilst another por- 
 tion is studded with tumours, which, on in- 
 cision, present nothing except black, putrid, 
 coagulated blood. 
 
 3. A disease that occasionally falls under 
 our notice, and in its pernicious tendency 
 equals those already described, is, when 
 the whole body puts on a flaccid ap- 
 pearance, with the exception of the lips, 
 which are hard, swollen, of a purple cast, 
 and frequently bloody. 
 
135 
 
 All these affections I at one time attributed 
 to our present mode of keeping Leeches, that 
 is, in small vessels, and greatly crovrded. Mr. 
 Baker, however, acquaints me, that he has 
 frequently seen Leeches taken from their 
 native abode, labouring under these several 
 states of disease. But when thus found, 
 their liberty is again restored to them, in 
 order to prevent the contagion spreading 
 among those already caught and in good 
 health. 
 
 These diseases (more particularly the ul- 
 cer, which I have found an almost constant 
 attendant upon the H. vulgaris) are parti- 
 cularly prevalent during the summer months. 
 And as they invariably proceed to a fatal ter- 
 mination, we should, when we find a Leech 
 in the least degree indisposed, immediately 
 remove it from the rest, to prevent the usual 
 ill consequences. 
 
 Although we are not in the possession of 
 
136 
 
 any effectual remedy to check the progress 
 of these destructive diseases, we are still for- 
 tunate in being enabled to guard against 
 their so frequent occurrence. This is to be 
 done by keeping them in capacious stone 
 jars or other large vessels, in the manner I 
 shall presently notice. 
 
 The water in which Leeches are kept 
 sometimes assumes a bloody tinge, when the 
 Leeches are to all appearance, in good health. 
 Should tins still take place after its frequent 
 renewal, we may expect a great mortality ; to 
 obviate which, or at least to lessen its effects, 
 it would be prudent to separate them, keeping 
 only a few together. The temperature of the 
 water should be, as much as possible, pre- 
 served uniform : all extremes of heat and 
 cold should be avoided ; and a situation 
 should be chosen free horn any unpleasant 
 smell. 
 
 Although it be adviseable, every seven or 
 
137 
 
 eight days, to change the water, yet the 
 followioir instances will shew tliat it is not 
 
 o 
 
 absolutely necessary. 
 
 Dr. Ferguson kept Leeches more than a 
 twelvemonth, and only renewed the water 
 two or three times ; which, he observes, con- 
 tinued pure, sparkling, and free from smell. 
 The only change noticed was, that a small 
 quantity of greenish matter had gathered 
 around the sides of the vessel.* 
 
 I learn from a medical practitioner in this 
 city, that he once kept a Leech in water un- 
 changed nearly two years. ^Vhen the Leech 
 died, it was reduced to about one third of its 
 original size. The water, during the whole 
 of this lime, as in the case just noticed, had 
 no unpleasant smell. 
 
 The author once kept a single Leech in 
 water unchanged during the summer-months, 
 and he found it equally active with othei’s, 
 
 * Medical and Physical Journal, vol xiii. p. 302. 
 
 T 
 
138 
 
 wliere the water was renewed every second 
 day. 
 
 W lien Leeches are kept in any consider- 
 able quantity, I would recommend them to 
 be placed in a large vessel, provided with a 
 false bottom so perforated as to allow them a 
 ready passage. This false bottom should be 
 raised from three to six inches above the real 
 bottom, or to such an extent as will admit 
 of a turf,* of nearly equal dimensions, being 
 placed between them. It should fit closely 
 to the sides, that the earth may not be 
 
 * The turf, from its fibrous and matted structure, affords' 
 to the Leech a ready means of disencumbering itself of the 
 epidermis; which, if suffered to remain, would not only 
 prove troublesome, but occasionally give rise to disease. 
 The Leech-dealers frcc|uently bring with them the Marsh 
 Horse-Tail (Equisetum PalustreJ, which answers the same 
 intention. Of this plant, in its dried state, in the early part 
 of spring and before the aquatic plants have acquired any 
 growth, they avail themselves, to lure the Leeches to the 
 surface, in order to their being more expeditiously caught. 
 It is usually thrown in an evening into ponds, &c. on the 
 surface of which it remains, and in the morning the Leeches 
 are found enveloped in its folds. 
 
139 
 
 disturbed by the frequent introduction of 
 fresh water. It is necessary that the vessel 
 be also furnished with a stop-cock, that the 
 water may be drawn off as often as it may 
 be considered expedient. 
 
 But previously to our placing tlie Leeches 
 in this vessel, they should be singly ex- 
 amined. If, on being handled, they contract, 
 and feel hard and firm, it affords the best in- 
 dication of their being healthy ; but should 
 they feel flabby, or exhibit protuberances or 
 white ulcerous specks on the surface, they 
 should be kept in jars by themselves, the 
 water and the turf of which should be 
 frequently renewed. 
 
 We now pass from the Preservation of 
 the Leech, to its Mode of Application and 
 Treatment. 
 
 When the application of Leeches is 
 judged expedient, the part on which it is 
 intended they shall fix, should be as clean as 
 
 T 2 
 
140 
 
 possible : it should the] efore be first washed 
 with soap and water, aud aiter wards with 
 water alone; whicii will be the more neces- 
 sary, sliould any liniment or embrocation 
 have been used. 
 
 The Ancients recommend us to remove 
 Leeches from the water, an hour at least pre- 
 vious to their application, on the ground that 
 they are thus rendered more voracious, and 
 afiix to tlie skin with the greater readiness. 
 Such is the practice even in the present day ; 
 and we find it frequently attended with 
 success. 
 
 Leeches are commonly affixed by inver- 
 ting a wine-glass containing as many as may 
 be required, upon the part affected. The 
 great disadvantage of this practice is, that 
 some of them frequently retire to the upper 
 part of the glass and remain at rest, defying 
 all attempts to dislodge them, without in- 
 curring the risk of removing those that may 
 have already fastened. 
 
141 
 
 To remedy this inconvenience, I would 
 recommend the employment of glass-vessels 
 of various sizes, but none of them more than 
 an inch in depth. They should be made to 
 assume various figures ; such as that of a 
 diamond, half-moon, &c. In Opthalmia or 
 Inflammation of the Eye, a glass of the half- 
 moon shape might be used with advantage. 
 But, for my own part, I always trust to their 
 application by the hand. Bring a Leech 
 toward the part whereon you intend to fix 
 it, and as soon as it begins to extend the 
 head, to seek an attachment, endeavour that 
 it may affix itself to the place required. 
 Some little dexterity is requisite to make the 
 Leech attach itself at the first point of con- 
 tact, or it often happens that it will pass over 
 a great extent of surface, without evincing 
 the least disposition to bite. In this case, 
 puncturing the part with a lancet offers the 
 only chance of success. When the patient 
 is fearful of the lancet, and one Leech only 
 
142 
 
 shall have bitten, where several are required, 
 it may be of use to remove it, which is 
 readily done, by inserting the nail of the 
 finger between its mouth and the skin. The 
 blood then flowing from the orifice, will 
 induce tlie remainder to bite with the great- 
 est avidity. As soon as the Leeches are 
 gorged, they drop otf; this usually happens 
 within ten or fifteen minutes. Sometimes 
 they remain affixed a considerable time, and 
 become indolent; but they are quickly roused 
 from this state by sprinkling them with a 
 few drops of cold water. 
 
 The Leech, when filled, contains from 
 half an ounce to an ounce of blood ; and 
 what is worthy of notice, this fluid is pre- 
 served in its stomach, in an uncoagulated 
 state, for two or three months, and without 
 j)roducing any offensive smell. The only 
 change it suffers, is that of becoming deeper 
 in colour, and a little thicker in consistency. 
 
 
143 
 
 Under some peculiar circumstances the 
 blood, however, will coagulate, and it is 
 then productive of disease. What peculiar 
 action takes place in the stomach of the 
 Leech, to preserve for so long a time the 
 blood in a state of fluidity, we cannot well 
 determine. It may, however, be urged as 
 probable, that a fluid is secreted, capable of 
 resisting the developement or play of those 
 affinities which are essential to the putre- 
 factive process. 
 
 When a Leech quits the part to which it 
 was affixed, and the blood continues to flow 
 longer than is required, the application of a 
 slight compress will usually restrain it ; but 
 should this at any time prove ineffectual, we 
 must have recourse to a compress steeped in 
 some styptic, as brandy or spirits of wine. 
 
 When fi’om their scarcity but few Leeches 
 can be procured, advantage may be taken. 
 
144 
 
 according- to an ancient custom, of snipping 
 oft' their tail ; the blood will then flow, drop 
 by drop, from the artificial opening, as fast 
 as the Leech sucks it. But it is of no use 
 to resort to this operation unless the Leech 
 is in the act of suction ; for should the pres- 
 sure from the column of descendin«- blood 
 be removed, this artificial opening would 
 be immediately closed by the strong action 
 of the circular muscles. With the same 
 view an incision may be made close to the 
 tail of the Leech, with a lancet. 
 
 I have frequently performed this experi- 
 ment, and what is remarkable, have found 
 them to suft'er, apparently, so little from the 
 operation, that they still drew the blood with 
 as much freedom as before. In one instance, 
 in a Leech just fallen off and fully gorged, I 
 employed this method of ridding it of its 
 contents ; and, severe as many might deem 
 this treatment, the Leech was no sooner re- 
 turned to its former situation, than it began 
 
145 
 
 sucking with the same avidity as when first 
 applied. Although the Leech appears at 
 the moment to suffer from this practice 
 but trifling inconvenience, yet it afterwards 
 becomes very languid : I would therefore 
 only propose its adoption, at a time when, as 
 before noticed, their scarcity might render 
 such a measure expedient. 
 
 To make a Leech disgorge, the most 
 common practice is, that of strewing the mu- 
 riate of soda, or common salt, over its body. 
 In a few seconds the blood is rejected, the 
 Leech assumes a coiled form, and loses its 
 activity and vigour ; and we seldom find it 
 again fit for use, until the expiration of four 
 or five days.* As the salt frequently blisters 
 
 * Upon this subject, Horn says, rather quaintly, “ Those 
 persons do not consider that blood is the most favourite and 
 salutary nourishment of this extraordinary creature [the 
 Leech] 5 and I would ask such inconsiderate persons, how 
 they would feel themselves if, immediatLdy after eating a 
 hearty dinner, any person was to give them a violent 
 emetic?” 
 
 U 
 
146 
 
 the body, we are advised to apply it only 
 to tlie mouth ; but I must remark that if 
 the lips are blistered, the same obstacle is 
 presented against its re-application. 
 
 To remedy this inconvenience, we are re- 
 commended to draw the Leech between tiie 
 thumb and finger of tiie left hand, keeping’ 
 up a regular and uniform pressure, until the 
 whole of tiie blood is removed. This prac- 
 tice is certainly preferable to the former; for 
 the Leech continues active, and will again 
 immediately afiix itself. But the great dis- 
 advantage is, our being scarcely able to 
 carry it into effect without injury to the 
 internal st^'iicture. 
 
 In preference to any of therse methods, and 
 one from which the Leech appears to suffer 
 the least inconvenience is, that of pouring 
 a small quantity of vinegar upon the head. 
 Following this mode of treatment, I have 
 succeeded in making a Leech bite four times 
 successively, coming off each time comjiletely 
 gorged with blood. 
 
147 
 
 It will be scarcely necessary to observe, 
 that Leeches recently applied should be 
 kept by themselves, and should be allowed 
 to retain for their nourishment and supports 
 about one third the quantity of the blood 
 they extract. 
 
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 Printed by John Evans Co. Bibstol. 
 

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 J.R. Johnson 
 
 1816