m 
 
 
 |lil|!Hpap#sa!feki; 
 
 
 
 
 
 
 THE SENSE OF 
 TASTE 
 
 •LHOLLINGWORTH 
 \T' POFFENBERGER, Jr 
 
Cornell University Library 
 BF 261.H65 
 
 The sense of taste, 
 
 3 1924 000 433 031 
 
B Cornell University 
 M Library 
 
 The original of tliis book is in 
 tine Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31924000433031 
 
THE SENSE OF TASTE 
 
Our Senses Series — Editor, G. Van N. Dearborn 
 
 THE SENSE OF TASTE 
 
 BY 
 
 H. L. HOLLINGWORTH, Ph.D. 
 
 Associate Professor of Psychology in Columbia University 
 AND 
 
 A. T. POFFENBERGER, Jr., Ph.D. 
 
 Instroctor in Psychology in Columbia University 
 
 NEW YORK 
 
 MOFFAT, YARD AND COMPANY 
 1917 
 
Copyright, igir. by 
 MOFFAT. YARD AND COMPANY 
 
 Published April, 1917 
 
L. S. H. 
 
 AND 
 
 F. K. P. 
 
EDITORIAL INTRODUCTION 
 
 Few people, comparatively, however intelligent 
 and generally thoughtful, have as yet stopped to 
 consider the surpassing interest and the unique 
 importance of Our Senses. Living gateways as 
 the sense organs are between ourselves and our 
 ever-changing surroundings, both spiritual and 
 niaterial, they constitute the channels not only of 
 our life-satisfaction, but of all our immediate 
 knowledge as well. If, then, in discussing them, 
 biological imagination and bi-eadth and depth go 
 hand in hand with technical knowledge of the 
 highest grade, the volumes comprised should be 
 both human and scientific. And these volumes 
 are so, and will be. It is because of such possibil- 
 ities that a series like the present, authentic yet 
 interesting and inexpensive, must appeal to the 
 intelligent man or woman of to-day. As contribu- 
 tions to psychology and to education their value is 
 certain to be great, as indeed is indicated by the 
 list of their authors, whom it would be superflu- 
 ous to praise or even to portray. 
 
 Small in number are the topics in all the won- 
 drous range of the science of living things that 
 are mote alluring for their very mystery and 
 romance than these same gateways by which we 
 
 vii 
 
VUl 
 
 EDITORIAL INTRODUCTION 
 
 may go out into " our world " and by which this 
 same great world may come into us and, for the 
 little span of life, lend us a feeling of home-dwell- 
 ing. 
 
 Within the past decade there has been a gen- 
 eral popular awakening from the former uninter- 
 ested attitude toward these phenomena of the 
 physical and mental processes by which we keep 
 in touch with the things outside ourselves. A fair 
 knowledge of the rudiments of biology, of physi- 
 ology, and of psychology now has become part of 
 the curriculum of our schools and colleges. And 
 of these three sciences it is psychology which has 
 entered so deeply into our everyday life — ^business 
 life as well as personal — that at last no one can 
 escape its influence. And no one wishes to, for 
 psychology in a sense has become the intellectual 
 handmaiden of all who think in terms of to-day, 
 with to-day's amazing development of insight 
 into the mortal meanings of our very selves, body 
 always as well as soul. Our scientific realization 
 of our true continuity with all things else goes 
 on apace, and our personal relations to the bound- 
 less, perhaps Infinite, Cosmos of consciousness, 
 life, and energy seem ever clearer. Thus, in a 
 way, the sense organs give us personal anchorage 
 in a Sea which else sometimes, from its very im- 
 mensity and stress, would overwhelm us. Our 
 range, although the broadest as yet vouchsafed tp 
 
EDITORIAL INTRODUCTION ix 
 
 life, is as it were but a mere line out into the com- 
 plexity of the Actual. The first step to the appre- 
 ciation of this complexity and its implications for 
 the human mind is knowledge of the conditions 
 of its acquirement, — of the sense organs and of 
 the perplexing brain behind them. 
 
 Editorial duty or privilege fails to know much 
 as yet of the detailed contents of these several 
 volumes. But the editor does know not a little 
 about the arrangers and expounders of the vol- 
 umes' contents, and he knows that they are women 
 and men of conspicuous sense — trustworthy in 
 every sense. The books are the best of their kind 
 and are in a class by themselves. They are the 
 standard authority for ordinary use. These vol- 
 umes when disposed as a red-backed set on one's 
 library shelf will be a set of books to be proud of. 
 And the high school boys and girls and their 
 fathers evenings and on Sundays and their 
 mothers at the club all alike will think of them as 
 highly valued friends, both wise and agreeable, as 
 pleasant to meet for an hour as the most welcome 
 visitor well could be. No higher " authority " 
 exists than that which these authors represent; 
 and it would be hard to find those who could set 
 forth " authority " more gracefully. Each knows 
 that literary enjoyment usually goes hand in hand 
 with that wisdom which extended is the director 
 of Life itself. 
 
X EDITORIAL INTRODUCTION 
 
 Although the sense of taste is more strictly a 
 "biological " sense than any of the other simple 
 senses of man — that is, more particularly con- 
 cerned with the underlying bodily life — it plays, 
 nevertheless, a very important part in our per- 
 sonal psychology. Many of us find in tasting one 
 of the fairly dependable satisfactions of our 
 everyday living; and Satisfaction, it seems upon 
 long reflection, comes pretty close to being the 
 long-sought " highest good." The wholly need- 
 less and harmful bodily overweight of many of us 
 attests how often this sense is made a malig- 
 nant fetish to lure us evilward. Eve tasted — 
 and in that alluring moment set an example too 
 plain and too significant ever to be ignored. 
 The sense of taste, none the less, is a wholly 
 respectable and dignified mode of obtaining 
 satisfaction. 
 
 And our respective " research magnificent " 
 would not be quite so interesting, not so adven- 
 turesome, were our sense of taste, instead of a 
 clear sense experience tingling always with some 
 kind of satisfaction, were it, I say, only a subcon- 
 scious instinct, part of the original organic nature 
 of man, working in the dark of consciousness. 
 And for a few of us, especially if we be chefs, or 
 cooks, or tea-tasters, or dyspeptics, or epicures, 
 or gluttons, or taste-perverts, and the like, taste 
 is, perhaps, one of the most important of all mor- 
 
EDITORIAL INTRODUCTION xi 
 
 tal experiences and of all scientific themes. And 
 to the children how much it is ! 
 
 Professor HoUingworth and his Columbia 
 colleague, Doctor Poffenberger, have written a 
 volume which seemingly would satisfy both the 
 scientific reader and the general readers who 
 from curiosity seek its information. The busi- 
 ness man as well as his wife sitting beyond the 
 living-room table will both find the something 
 they hoped to find; and the keen school teacher 
 and the all too infrequent schoolmaster will find 
 part of that material for the development of in- 
 tensive sense-training now obviously indispensable 
 to the further evolution of our school system. For 
 even taste, least intellectual of our senses, can be 
 intensively and hence usefully trained and thus 
 education be furthered. 
 
 The authors need no introduction to the edu- 
 cated million, but if they did, this book would 
 furnish one which the most exclusive hardly could 
 disdain. They are to be congratulated on the 
 success with which they have put much that is at 
 once interesting and scientific up to the hour into 
 little space, with " war-time economy." The 
 authors have covered their field well. 
 
 The editor takes this first opportunity to invite 
 criticism of whatever trend, and to ask for sug- 
 gestions, whether from sense-gluttons or from 
 
xii EDITORIAL INTRODUCTION 
 
 philosophers, for the better conduct and the fur- 
 therance of this series and of that other series, on 
 " The Life of the Child," which he is -editing. As 
 is true in a wholly different field of conquest, here, 
 too, lies safety in numbers, and where there are 
 many men there are many minds. As all authors 
 at least will hasten to agree, not even an editor 
 knows all that might be known. 
 
 G. V. N. D. 
 
 Cambridge. Massachusetts, 
 January, 1917. 
 
PREFACE 
 
 The sense of taste is in numerous ways the most 
 paradoxical of all the senses. Although, as a 
 source of sense impression, it can afford the 
 keenest immediate feelings of pleasure and de- 
 light, the books on aesthetics and art have little 
 or nothing to say about it. Skill in the compound- 
 ing of tastes and flavors, or discrimination in their 
 relish, brings the expert neither artistic recogni- 
 tion nor social eminence. Taste, it is constantly 
 asserted, is one of the " lower senses," and neither 
 in the enjoyment of it nor the ministration to it 
 is there to be acquired the merit and general 
 esteem that readily distinguish an art from a 
 service. 
 
 Nevertheless we commonly use the word 
 " taste " for the expression of just those qualities 
 of fine discrimination and delicate perception 
 which are most conspicuously the marks of aes- 
 thetic appreciation. In our choice of figures of 
 speech we reserve " vision " for the impersonal 
 and remote intuition of the seer and the philoso- 
 pher. " Touch " we use to express such intimate 
 and personal impressions as sympathy and pity. 
 
 xiii 
 
xiv PREFACE 
 
 " Sound " seems best to indicate, through " noise " 
 or " tone," either the self-seeking clamor of 
 aggression or the mere passive possession of a 
 certain richness of quality. " Odor," in its most 
 common figurative use, suggests the reprehensible 
 and undesirable motive. " Warmth " and " chill " 
 bespeak at once the depth of emotion or afFection. 
 But the special fineness of soul which shows itself 
 in the active and judicious choice of the appro- 
 priate and the harmonious, the subtly fitting and 
 the delicately adapted, seems best expressed by 
 the name of one of the " lowest " and most " vul- 
 gar " of senses, — " taste." Whether the judg- 
 ment be exercised in the choice of color harmony 
 or musical composition, costume or personal orna- 
 ment, architecture, monument, design or arrange- 
 ment, poetry or passing jest, rug, menu, pastime 
 or associates, it is the sense of taste which fur- 
 nishes the apt name for the critical capacity. 
 
 Not only is it in the usages of language that 
 taste is a paradoxical sense ; it is at the same time 
 one of the most ancient of the special senses and 
 also one about which exact knowledge is most dif- 
 ficult to acquire. It seems to afford a multitude 
 of varying and distinctive nuances of sensation, 
 yet it can boast but a meager equipment of four 
 fundamental sense qualities. It is a primitive and 
 well-established sense in the evolution of man, and 
 individuals might therefore be expected to re- 
 
PREFACE XV 
 
 setnble each other closely in their experience of it ; 
 yet the most trite of proverbs insists that " there 
 is no accounting for tastes." Indeed, in some lan- 
 guages it is even impossible to find distinctive 
 names for such common taste experiences as bitter 
 or even salt and sour. A survey of the phe- 
 nomena and laws of the sense of taste reveals, 
 in fact, no end of curious and interesting situar 
 tions. 
 
 Of particular interest are the recent demonstra- 
 tions of the great importance of taste for the gen- 
 eral well-being of the organism. With the devel- 
 opment of civilized modes of living men cease to 
 rely implicitly or entirely on the sense of taste in 
 thpir discrimination between wholesome and dele- 
 terious foods. They substitute for taste the evi- 
 dence of the commercial trade-mark, the label, 
 and the pure-food guarantee. It might have been 
 supposed that under such circumstances the sense 
 of taste would deteriorate through loss of func- 
 tion. But recent studies show that sensations of 
 taste do far more than serve as clues to the ac- 
 ceptance or rejection of food. Such sensations ap- 
 pear, in fact, to be the initial stimulus to the whole 
 series of digestive and assimilative processes on 
 which the well-being of the organism depends. 
 In much the same way the dulling or perversion 
 of the taste sensations is often seen to constitute 
 an early warning of grave disorder in the system 
 
xvi PREFACE 
 
 as a whole, and their restoration to presage the 
 return to normal health. 
 
 Developing as one of the earliest forms of sen- 
 sitiveness, intimately associated with the vital 
 processes of life and growth, affording manifold 
 richness of pleasure and aversion, full of para- 
 doxical surprises and puzzling problems, and 
 figuratively expressing one of the rarest of human 
 qualities, " the sense of taste " constitutes one of 
 man's most interesting contacts with the outer 
 world. 
 
 In the chapters which follow an attempt is 
 made to portray this contact in a manner which 
 is both clear and concrete, yet scientifically accu- 
 rate and technically complete. There are first 
 considered the actual experiences which the sense 
 of taste affords, their character, their analysis into 
 the elementary qualities, and the classification, 
 relations, and manner of combination of these 
 qualities. A consideration of the delicacy of the 
 taste sense, the precision of taste discrimination, 
 and their methods of measurement, is followed by 
 a discussion of the time relations of taste sensa- 
 tions, and a description of various special char- 
 acteristics and phenomena of normal and abnor- 
 mal tastes. 
 
 At this point there is presented a detailed de- 
 scription and illustration of the mechanism and 
 function of the organ of taste, its gross structure 
 
PREFACE xvii 
 
 and anatomy, its accessory apparatus, its more 
 minute nervous basis and composition, and its 
 evblution in the individual and in the lower animal 
 forms. Chapters are given to the nature of the 
 external stimulus which provokes taste sensations, 
 to disorders of the taste sense, to the differences 
 between individuals, and to the function of sensa- 
 tions of taste in the higher mental processes of 
 ima^nation, association, memory, and emotion. 
 Finally, an account of the function of taste in the 
 life of the organism is followed by a consideration 
 of the place of the sense of taste in aesthetics and 
 art, and in the complex interplay of human 
 thought and social communication. 
 
CONTENTS 
 
 CHAPTER PAGE 
 
 Editorial Introduction . . vii 
 
 Preface xiii 
 
 I The Qualities of Taste . . i 
 
 The Taste Manifold — The ClaBsiflcation of 
 Tastes — Taste Blends and Fusions — The 
 Poverty of Taste — ^Psychological Analysis 
 of the Taste Qualities — Distribution of 
 the Taste Qualities — The Vocabulary of 
 Taste. 
 
 II The Organization of the 
 
 Tastes 27 
 
 System and Organization in Other Senses 
 — Taste Mixtures and Compounds — Com- 
 pensation, Antagonism, and Neutralization 
 — Contrast Phenomena — ^After Images of 
 Taste — The Schema of Taste Relations. 
 
 III The Sensitiveness of Taste . 43 
 
 Various Measures of Sensitiveness — ^The 
 Threshold of Taste Sensation — Relative 
 Sensitivity of Taste and Smell — ^The Dis- 
 crimination of Tastes — ^Adaptation and 
 Fatigue — Acquired Tastes — ^The Early 
 Development of Taste. 
 
 IV Time Relations of Taste Quali- 
 
 ties 55 
 
 "The Inertia of the Taste Organs — ^Reac- 
 tion Time to Taste Stimuli — Determinants 
 of Reaction Time to Taste. 
 
 xix 
 
XX CONTENTS 
 
 CHAPTER 
 
 PAGE 
 
 V The Sense Organ of Taste . 60 
 
 Compariaon with other Sense Organs — 
 The Salivary Glands and Their Activity — 
 The Tongue: Its Muscles and Covering 
 Membranes — Classification of Fapillee — 
 The Determination of the Taste Areas. 
 
 VI Sensory Elements of the Taste 
 
 Mechanism . . . .78 
 
 Taste Buds and Their General Character- 
 istics — Supporting Cells, Gustatory Cells, 
 and Nerve Filaments — Relations Among 
 the Structures within the Taste Bud — The 
 Sensory Nerves of Taste — ^The Cerebral 
 Taste Centers. 
 
 VII Taste-Producing Substances . 92 
 
 Adequate and Inadequate Stimuli — Ade- 
 quate Taste Stimuli — Inadequate Taste 
 Stimuli. 
 
 VIII The Function of the Taste 
 
 Mechanism . .103 
 
 The Function of Tongue and Salivary 
 Glands — ^The Function of the Taste Buds. 
 
 IX The Development of Taste in 
 
 the Individual . . .116 
 
 Development Before Birth — ^Development 
 of Taste In Infancy and Childhood — Taste 
 in the Adult — Structural and Func- 
 tional Differences Among Individuals — In- 
 dividual Differences Due to Pathological 
 Changes — Racial Diflferences in the Struc- 
 ture and Function of the Taste Organs. 
 
CONTENTS xxi 
 
 CHAPTER PAGE 
 
 X Evolution of Taste . . . 128 
 
 Senaitmty of the Unicellular Organisms 
 — " The Chemical Sense " — Chemical Sense 
 in Fishes — ^Land-Dwelling Animals. 
 
 XI Gustatory Imagination and 
 
 Memory 144 
 
 The Nature and Frequency of Mental Im- 
 ages — ^Mental Images of Taste — ^Taste in 
 Dreams and in Hallucinations. 
 
 XII Unusual and Abnormal Taste 
 
 Experiences . . . .151 
 
 Gustatory Hallucinations and Auree — ^Par- 
 tial and Complete Ageusia — Taste Hal- 
 lucinations of the Insane — Synsesthesias of 
 Taste — ^Perversions of Taste. 
 
 XIII Food and Flavor . . .158 
 
 The Biological ROle of Taste — ^Taste and 
 Digestion — ^Experimental Evidences — The 
 Function of Taste in the Organic Economy. 
 
 XIV The ^Esthetic Value of Taste 168 
 
 The Higher and Lower Senses — ^Boimty of 
 Nature and Ecclesiastical Censorship — The 
 Psychophysical Attributes — The Tendency 
 to Adaptation — Spatial , Attributes of 
 Taste Qualities — Immediate Affective 
 Value of Taste — ^Development in the In- 
 dividual and the Race — The Imaginative 
 Value of Taste — The Non-Social Char- 
 acter of the Lower Senses — The Unsys- 
 tematic Relations of Taste Qualities — ^The 
 Motive of iEisthetic Products. 
 
 Index 197 
 
ILLUSTRATIONS 
 
 Diagram showing relations between the taste qualities 40 
 
 Sketch of the tongue 69 
 
 Diagram showing some of the various courses which 
 
 have been advocated for the taste fibers in man 88 
 
THE SENSE OF TASTE 
 
 CHAPTER I 
 
 The Qualities of Taste 
 
 The Taste Manifold 
 
 The casual observer would probably feel that 
 any attempt to enumerate and arrange in a logical 
 scheme the infinitude of tastes and flavors 
 would be an impossible task. To him it might 
 seem that nearly everything in the world pos- 
 sessed its own peculiar taste. Such an observer 
 would also be likely to think it impossible and 
 thankless to attempt to reduce to their necessary 
 limits the various kinds of substance of which 
 this infinitude of things is made up. But the 
 chemist would readily be able to show him that the 
 infinitude of substances consisted, as a matter of 
 fact, only of various forms and combinations of 
 less than one hundred " elements," and that from 
 these elements one could produce, by appropriate 
 selection and apportionment, any one of the in- 
 finitude of substances. 
 
 Is it then possible, in the field of our sensa- 
 
2 THE SENSE OF TASTE 
 
 tions, to reduce to elemental categories or units 
 the manifold * of concrete sense experience ? In 
 the case of visual sensations almost everybody 
 knows that there are certain so-called " primary " 
 colors, from which can be produced the whole 
 range of color experiences known to man. Blue 
 and yellow, red and green, these are the primary 
 colors, and if to these, in their varying inten- 
 sities, be added gray, with its range of bright- 
 nesses, we have the elementary components of 
 all our visual experience. Such a distinctive color 
 as that of fire clay, for example, may thus be said 
 to contain, in specified degree and proportion, red, 
 yellow, and gray, while the familiar color of a 
 wild flower may contain, in specified relations, red, 
 blue, and gray. 
 
 In a strict psychological sense, it remains true 
 that each color experience is relatively unique and 
 distinct. But it can readily be shown that 
 these psychological fusions and compounds are 
 elaborations of more unitary experiences which 
 have as their basis distinct mechanisms in the 
 nervous system and sense organs. For example, 
 the sensation of " heat " is a readily recognizable 
 and identifiable experience, yet the physiologist 
 tells us that there is no separate sensory apparatus 
 
 *By a "manifold" is meant a great variety of objects or 
 experiences organized into one system or constituting one 
 field. 
 
THE QUALITIES OF TASTE 3 
 
 for this impression. Cold and warmth, we are 
 told, depend on the stimulation of specific nerve 
 endings. When these two types of endings, in the 
 same general region of the skin, are simultane- 
 ously stimulated, as the result of the application 
 of a stimulus with very high temperature, there 
 arises that new experience of " hot," which is in 
 this sense a combination of warmth and cold. 
 
 Is it similarly possible to reduce to elementary 
 units the rich manifold of taste and flavor? If 
 this can be done, in what way must such an analysis 
 proceed? What principles of classification are 
 revealed, and what and how numerous are the 
 elementary taste qualities ? The various attempts 
 that have been made to analyze the taste manifold 
 are as interesting as their results are instructive. 
 
 The Classification of Tastes 
 
 One method of classifying sense qualities that 
 has often been advocated uses as its basis the 
 varieties of objects, agencies, or stimuli * by the 
 application of which the sense qualities are pro- 
 duced or aroused. Thus the whole field of sense 
 experience might be divided into thermal, elec- 
 trical, mechanical, photic (produced by light), 
 etc. But such sensations as are aroused by elec- 
 trical stimuli, for example, may be auditory, 
 
 * By a " stimulus," in this connection, is meant any object, 
 force, or agent that acts upon a sense organ. 
 
4 THE SENSE OF TASTE 
 
 visual, cutaneous, gustatory (having to do with 
 taste), etc., while these same varieties of sensory 
 experiences may be aroused in some cases by 
 mechanical stimulation. Hence the classification, 
 of stimuli does not yield an adequate analysis of 
 modes of sensation. In the field of taste this 
 method, although it has been seriously attempted, 
 is equally futile. Thus various writers have at- 
 tempted to group taste sensations according to 
 the species of plants and animals whose tissues 
 possessed sapid (tastcrpro.ducing) qualities. It 
 is obvious that this method is unsatisfactory, since 
 it is by no means true that all specimens of a given 
 vegetable taste alike. Even different parts of the 
 same plant have widely different tastes, and in- 
 deed the taste of a given part varies widely with 
 time and circumstances. 
 
 Even Chevreul, a famous early student of the 
 sense of taste, adopted a chemical classification, 
 on the basis of the composition of the substance 
 tasted. Here again it is true that substances 
 chemically very dissimilar may possess tastes 
 which are strikingly alike. Thus acetate of lead, 
 chloroform, and cane sugar, which, chemically 
 considered, are very dissimilar, may easily be 
 mistaken for each other if their taste alone is 
 relied on ; while starch, which is chemically closely 
 related to sugar, has no taste. It is also true that 
 such different tastes as sweet and bitter may char- 
 
THE QUALITIES OF TASTE 5 
 
 acterize substances which are chemically very 
 closely related. 
 
 It is, however, true that certain broad lines of 
 chemical classification may be drawn. Thus those 
 substances belonging to the colloid * group are 
 tasteless, the crystalloids all being sapid. When 
 substances are arranged according to the " peri- 
 odic law" of chemistry, the elements present in 
 sweet-tasting substances are in general neither ex- 
 tremely positive nor extremely negative. While 
 it is the general rule that soluble alkaloids are 
 bitter, acids sour, sugars sweet, and salts salty, 
 there are many curious exceptions in every case. 
 " It is true that we get the taste of salt only from 
 chemical salt; but there are chemical salts that 
 taste sweet, others that taste bitter, others again 
 that have no taste at all." Similarly, while it is 
 true that sour tastes belong to acids, it is by no 
 means true that all acids taste sour. Moreover, 
 s^ga^ of lead,jvhich is ajalt^tastes_sweet; while 
 suiphate~bf mag^^ajand other salts_taste_bitter. 
 
 Indeed, it is true that there are substances 
 which have morelHaiToneiastertfie taste varymg 
 with Were^onoithejtm 
 stancef is applied. Thus saccharine, sulphate of 
 magnesiaT^d acetate of potassium are said to 
 have sweet or acid taste if applied to the side or 
 tip of the tongue; whereas they are bitter if ap- 
 
 * Resembling jelly or glue, uncrystalline in character. 
 
6 THE SENSE OF TASTE 
 
 plied to the posterior part. Tiiere are various 
 other substances which show similar changes in 
 taste according to the point of their application. 
 However such facts may be explained, it is clear 
 that the classification of taste along chemical lines 
 is not only beset with difficulties, but that even in 
 attempting such classification we resort to the use 
 of a more immediate classification, indicated by 
 such words as sweet, sour, etc. 
 
 This resort to an immediately descriptive 
 classification suggests that the various taste ex- 
 periences, regardless of the stimulus provoking 
 them, have certain similarities as direct experi- 
 ences. This further suggests that a strict psycho- 
 logical classification, based on the attributes of 
 tastes themselves, should be found through analy- 
 sis. In the case of sensations in general, such a 
 type of classification is the one that seems most 
 satisfactory. Certain sense experiences, such as 
 red, yellow, orange, seem, as a matter of imme- 
 diate experience, to belong together and to be 
 essentially different from such experiences as 
 warmth, tickle, noise, dizziness, etc. Further- 
 more, it is found possible to pass by gradual steps 
 of transition from red to yellow, through an in- 
 tervening orange, while there exists no such inter- 
 mediate region between red and tickle. As a 
 matter of immediate experience, then, and regard- 
 less of the nature of the stimulus, or, so far as we 
 
THE QUALITIES OF TASTE 7 
 
 may be aware, of the part of the body stimulated, 
 certain sense experiences seem to belong together, 
 to constitute a certain mode of sensation, such as 
 pressure, sound, etc. 
 
 Is it now possible to apply a similar test to the 
 various qualities which comprise the mode or 
 sense of taste, and thus arrive at an adequate 
 classification and analysis of these qualities ? The 
 earliest attempts to analyze the tastes by this psy- 
 chological method were often amusingly miscalcu- 
 lated. Thus Chatin, in 1880, presented a scheme 
 in which the total manifold of taste was first 
 divided into agreeable tastes and disagreeable 
 tastes. The agreeable tastes were typified by 
 those we call sweet, and the disagreeable by those 
 we call bitter. It was, of course, at once neces- 
 sary to indicate certain intermediate conditions in 
 this scheme for a variety of tastes which were 
 neither clearly agreeable nor markedly unpleas- 
 ant. Moreover, it is a matter of common experi- 
 ence that a taste which is agreeable to one person 
 (such as tobacco, olives, mustard) may be de- 
 cidedly obnoxious to' another person, or, indeed, 
 even to the same person on a different occasion; 
 so that such a classification cannot be said to rep- 
 resent in any fundamental way an analysis of 
 tastes. 
 
 There have been a great variety of classifica- 
 tions proposed on this direct descriptive basis. 
 
8 THE SENSE OF TASTE ^ 
 
 and a comparison of the various schemes at once 
 suggests that the task is by no means as simple as 
 it might seem. The number of elementary tastes 
 ranges widely, some investigators enumerating 
 five or six times as many fundamental taste qual- 
 ities as others have recognized. 
 
 Haller enumerated twelve different qualities — ■ 
 stale, sweet, bitter, sour, sharp, tart, spicy, salt, 
 urinous, putrid, spirituous, nauseating. It is evi- 
 dent that this classification represents only a tran- 
 sition step toward a psycholo^cal analysis and 
 that it is by no means free from the suggestion of 
 provoking substances (spirituous, putrid) and the 
 suggestion of effects produced (nauseating) . 
 
 Linnaeus recognized somewhat fewer cate- 
 gories, — giving the following ten as fundamental, 
 — sweet, spicy, oily, mucous, salt, styptic,* bitter, 
 sour, aqueous, and dry. 
 
 Other authors have been content with indicat- 
 ing eight elementary tastes. Both Bain and 
 Wundt have proposed a sixfold classification, as 
 follows, — sweet, bitter, saline, alkaline, acid, and 
 astringent or metallic. Most modern authorities 
 reduce the number of elementary tastes to four, 
 — sweet, salt, sour, bitter, — ^while at least three 
 investigators have advocated a simple twofold 
 classification. Into sweet and bitter. 
 
 •Styptic,— causing contraction of tissus. 
 
THE QUALITIES OF TASTE 9 
 
 Taste Blends and Fusions 
 
 These divergent accounts of the elementary 
 taste qualities are in large measure to be ex- 
 plained by the exceeding complexity of those 
 experiences which we in everyday life refer to 
 as " tastes." It was long ago shown that a classi- 
 fication of the various senses on the basis of the 
 gross *' sense organs " or parts of the body in- 
 volved is as inadequate as one based on the nature 
 of the stimulating agent. The eye as a gross 
 sense organ yields experiences of pressure, pain, 
 temperature, and strain, as well as experiences of 
 color and brightness. But these varied sensations 
 we recognize as belonging, as experiences, to 
 quite distinct modes. Even more complex are the 
 varied sense experiences which we may receive 
 through stimulation of the tongue and the sur- 
 rounding tissues. For the tongue as an organ 
 yields not only sensations of pure taste quality, 
 whatever these may be, but It also gives rise to 
 experiences of pressure with the varying char- 
 acteristics of smooth, rough, moist, dry, contact, 
 tickle, etc. ; to experiences of pain, with the rang- 
 ing characteristics and intensities, such as sting, 
 smart, prick, burn ; to experiences of temperature, 
 such as cold, warmth, heat; and to a vast complex 
 of kinaesthetic or muscular experiences of contrac- 
 tion, torsion, strain, expansion. 
 
lo THE SENSE OF TASTE 
 
 In common experience these qualities of pres- 
 sure, pain, temperature, and kinaesthesis are 
 scarcely discriminated from the purely gustatory 
 or taste qualities themselves. Thus we speak of 
 " oily," " fatty," and " greasy " tastes, in which 
 the " smoothness " is certainly identical with that 
 felt by the fingers and other parts of the skin. 
 Similarly the pungent, astringent, puckering, bit- 
 ing " tastes " may come from substances which 
 have no taste at all in a strict sense, but which 
 produce definite smarting or stinging sensations 
 when applied to the surface of the skin or to ex- 
 posed nerve endings (pepper, camphor). The 
 puckering quality can be shown by the charac- 
 teristic muscular reaction to be largely kinaesthetic 
 and tactual in its origin. The difference in 
 " taste " between cold ice cream and the same sub- 
 stance when melted indicates how much of the 
 flavor is due to touch sensations and sensations of 
 temperature. One observer, indeed, reports the 
 experience of four different qualities of sensation 
 from the stimulation of a single papilla, — a 
 touch, a temperature, a taste, and a pain sensa- 
 tion. 
 
 Further, many substances, in addition to these 
 locally aroused experiences of touch, tempera- 
 ture, pain, and movement, set up strong organic 
 reactions In more or less remote regions as well 
 as strong affective reactions: such as choking. 
 
THE QUALITIES OF TASTE ii 
 
 nausea, and vomiting, on the one hand, and ex- 
 treme unpleasantness, disgust, distress, strain, and 
 shock, on the other. In many cases these imme- 
 diate reactions seem to be reflex or instinctive in 
 their origin, and in other cases they seem to be 
 conditioned reactions, based on past experiences 
 and associations. Thus in one case .the " taste " 
 of ice cream, which was once agreeable enough, 
 has come to be immediately nauseating in char- 
 acter. 
 
 In spite of all these facts many of the classifi- 
 cations of taste qualities have included the 
 " oily," the "nauseous," the " astringent," etc., as 
 primary taste experiences. Even if the complica- 
 tions we have thus far alluded to were the only 
 ones concerned, it would be clear enough that the 
 " tastes " and " flavors " of everyday conversa- 
 tion I'epresent very complex fusions and com- 
 pounds, and that an analysis of the true taste 
 qualities, if such there be, must take these factors 
 into account in some very careful experimental 
 way. 
 
 But we have left until this point a single com- 
 plicating factor which in itself is sufficiently seri- 
 ous to call for very careful technical procedure 
 in the examination of the sense of taste. This is 
 the fact that a very great number of our so-called 
 tastes are not tastes at all, but really odors. The 
 sense organ of smell is so situated that it may be 
 
12 THE SENSE OF TASTE 
 
 stimulated not only in the ordinary way, through 
 particles borne into the nostrils by currents of air 
 from the outside, but also by particles and vapors 
 which pass up, from the mouth cavity, behind the 
 soft palate, by way of passages called the " pos- 
 terior nares." 
 
 In this way it happens that tasteless substances, 
 with definite odor, are mistakenly supposed to 
 have taste. In 1824 Chevreul reported a very 
 simple experiment with which his name has since 
 been universally associated. He pointed out that 
 it is impossible to separate the action of a sub- 
 stance on the touch corpuscles of the tongue from 
 its action on the taste buds themselves. He ob- 
 served, however, that by a very simple expedient 
 it is possible to eliminate to some degree the fac- 
 tor of odor. His classical experiment consisted 
 in excluding the sense of smell in large part by 
 pressing the nostrils with the fingers while the 
 substance to be examined was presented to the 
 tongue. In this manner he observed that a piece 
 of camphor gum which had seemed to have a 
 very distinctive taste had in reality no taste at 
 all. When the nostrils were closed all that could 
 be observed as the result of placing camphor on 
 the tongue was a peculiar pricking sensation of 
 touch, similar to that produced by various other 
 substances. The sensation produced by the cam- 
 
THE QUALITIES OF TASTE 13 
 
 phor was thus not a taste at all, but a fusion of 
 odor and touch. 
 
 If, under the simple conditions of Chevreul's 
 experiment, the various substances be reduced to 
 a state of like consistency, so that they cannot be 
 recognized by the tactile sense, observers are 
 usually much amazed to discover that through 
 taste alone It Is impossible to distinguish between 
 quinine and coffee or between apple and onion. 
 Many familiar experiences of daily life testify to 
 the large contribution which the sense of smell 
 makes to the supposed taste. How "tasteless " 
 are our fruits, wines, cigars, and vegetables when 
 one has a cold in the head, and the free passage 
 of odorous particles to the organ of smell is ob- 
 structed ! How often has the nasty taste of medi- 
 cine been softened by Chevreul's simple technic 
 of " holding the nose " ! There are some cases 
 in which the reverse of this situation occurs and 
 volatile substances, entering the mouth through 
 the nostrils, stimulate the taste buds in the upper 
 and back part of the mouth. In such relatively 
 rare cases the real taste Is mistakenly Interpreted 
 as an odor. In this way chloroform seems to 
 have the characteristic odor which is in all prob- 
 ability a sweet taste due to stimulation of the taste 
 buds by the chloroform vapor. 
 
 Why should It be the rule that, since the taste 
 and smell qualities are to be confused, smell 
 
14 THE SENSE OF TASTE 
 
 should so commonly sacrifice its claim, so that 
 odors are called tastes rather than vice versa? 
 No doubt this is true largely because of the cus- 
 tomary presence of sensations of pressure, tem- 
 perature, movement, and resistance which are 
 localized in the mouth and in the organ of taste. 
 These accompanying sensations suggest that the 
 taste organs are active in determining the result, 
 even when no true taste qualities are present. It 
 is common for sensations to be displaced in some 
 such way as this, just as the blind man, who is 
 really getting sensations from stimuli in the palm 
 of his hand, seems to be getting them at the end 
 of his walking stick; or just as a faint sound may 
 seem to come from any source to which we direct 
 our attention. Similarly, the whole complex of 
 touch, taste, and odor experienced as the result 
 of " sniffing " at a particular substance are quite 
 likely to be credited entirely to the sense of smell. 
 
 The Poverty of Taste 
 
 Here, then, is a most interesting situation, 
 which has been described by the use of two apt 
 phrases : " the poverty of taste " and " the self- 
 sacrificing character of smell." Our analysis has 
 tended constantly to rob the sense of taste of the 
 richness which we ordinarily credit to it. In fact, 
 modern authorities agree that there are only four 
 qualities which can be truthfully classed as tastes, 
 
THE QUALITIES OF TASTE 15 
 
 namely, sweet, salt, sour, and bitter. What we 
 took to be the taste manifold is really a meager 
 equipment of four qualities, with such variations 
 of intensity and combination as these may pos- 
 sess. Both the richness and the raanifoldness 
 come from qualities of other senses, parading 
 under the guise of taste. Smell especially is prone 
 to sacrifice its claim in favor of its neighbor, and 
 it is common indeed for us even to use taste names 
 in describing odors ; we speak of " sweet 
 odors " and " sour smells," although sweet and 
 sour are primarily taste qualities. Smell, then, 
 not only entirely yields many of its qualities to 
 the various " taste blends," but allows some of 
 its own sensations to pass under taste names. 
 
 Patrick has reported extended observations in 
 which he studied the taste experiences of an 
 anosmic, — a person who had lost the sense of 
 smell. In some of his experiments this woman, 
 with two other women as control subjects, after 
 having been blindfolded, attempted to identify 
 various substances taken into the mouth. The 
 general principles on which the experiments were 
 based are stated as follows : "In theory those 
 substances not recognized by any of the observers 
 depend for their recognition upon sensations of 
 sight; those recognized by the normal observers 
 but not by the anosmic depend upon sensations of 
 smell for their recognition; while those recog- 
 
1 6 THE SENSE OF TASTE 
 
 nized by all observers depend upon either taste, 
 touch, or muscle sensations." It was further sug- 
 gested that those substances recognized by the 
 anosmic but not by the normal subjects would 
 seem to depend in the main upon touch or muscle 
 sensations. 
 
 These experiments disclosed many curious and 
 unexpected facts. Breads and meats, butter, 
 cream, olive oil, and various fruits and vegetables 
 could not be easily identified when only sight was 
 excluded. One of the women, a housekeeper of 
 long experience, could not recognize raw turnip, 
 raw potato, boiled pumpkin, cranberry sauce, or 
 fresh pear when she was blindfolded. 
 
 Chicken, turkey, and quail were found to differ 
 surprisingly little in actual taste, especially if their 
 characteristic texture, smoothness, and other 
 tactual qualities were eliminated or disguised. 
 The various values placed upon different meats, 
 breads, etc., in the general esteem would seem to 
 depend in great measure on associated ideas and 
 emotions, rather than on their actual qualities for 
 taste. 
 
 Especially interesting is the list of substances 
 which were recognized and correctly named by 
 both of the normal women in these experiments, 
 but which the anosmic was unable to identify. 
 Patrick enumerates twenty-seven such common 
 substances. Among them, by way of example. 
 
THE QUALITIES OF TASTE 17 
 
 were vanilla extratt, pineapple syrup, banana, 
 grape, quince, strawberry, tea, chocolate, sour 
 milk, kerosene, claret, rhubarb, onion, eggs, and 
 boiled turnips. The results suggest that these 
 substances, although they seem to have very char- 
 acteristic tastes, are actually differentiated and 
 recognized on the basis of their olfactory rather 
 than their gustatory or tactual qualities. 
 
 One justification of this olfactory sacrifice is 
 suggested by the fact that biologically one of the 
 most important functions performed by smell is 
 that of aiding in the discrimination of food. 
 Through smell the animals perceive at a distance 
 a substance which may offer itself as possible 
 food. Biologically, the immediate guide to the 
 acceptance or refusal of food is the sense of taste. 
 In so far as smell is in part a subordinate servant 
 in this matter, and hence becomes easily associated 
 with such reactions as " eating " or " not eating," 
 no injury is produced through the occasional con- 
 fusion of the two modes. 
 
 We have thus reduced the rich manifold of 
 taste to the qualities of sweet, salt, sour, and bit- 
 ter, — four meager qualities as compared with the 
 numerous unanalyzable qualities of various of the 
 other sensory modes. We have now to show by 
 what logic, through what technic, and on the 
 basis of what evidence, we are compelled to grant 
 to taste four qualities rather than two or twelve, 
 
1 8 THE SENSE OF TASTE 
 
 and why the final grant consists of these particu- 
 lar four rather than others. 
 
 Psychological Analysis of the Taste Qualities 
 
 • As Chatin long ago observed, " The three 
 senses, — taste, touch, and sm^U, — are so inti- 
 mately combined that they seem to refuse to yield 
 themselves to minute analysis." These associa- 
 tions seem to be even stronger than those between 
 the various taste qualities^ of which Ladd and 
 Woodworth have remarked, " On the whole it ap- 
 pears as if the four tastes were rather isolated 
 from each other, each representing almost an in- 
 dependent sense. There is much blending, to be 
 sure, but the amount is apparently no greater be- 
 tween one taste and another than between tastes 
 and odors.'l 
 
 We may now fairly ask how these four qual- 
 ities may be made to reveal their elementary and 
 independent character, once we have eliminated 
 the complicating factors introduced by the intru- 
 sion of qualities from other, senses. 
 
 The first appeal is to common observation and 
 experience, according to which the four taste 
 qualities, — sweet, sour, salt, and bitter, — stand 
 out as conspicuous classes within which may be 
 placed a great variety of " taste blends." Thus 
 many substances, while having more or less dis- 
 tinctive flavors, resemble each other in that un- 
 
THE QUALITIES OF TASTE 19 
 
 analyzable quality which we call sweetness. The 
 only question here is whether or not we should 
 also include qualities other than these four as .ulti- 
 mate and irreducible. If we refer back to the 
 lists of tastes proposed, we find that many of 
 them are such as can be shown to be analyzable 
 into one or more of these four qualities, plus the 
 intrusion of tactile, thermal, kinaesthetlc, and 
 olfactory qualities. Such tastes as nauseating, 
 aqueous, astringent, styptic, putrid, etc., are 
 easily ruled out on this score alone. Introspec- 
 tively, by simple experimental variation, or by 
 casual observation, the complex character of 
 many of these tastes is easily revealed, and when 
 the non-gustatory components are eliminated the 
 residue falls readily under one or other of our 
 four qualities. 
 
 These reductions are borne out by definite ex- 
 periment. The tactile (touch), thermal (temper- 
 ature), and kinaesthetic (movement) factors are 
 kept constant and reduced to a minimum by ap- 
 plying minute amounts of various solutions to 
 single papillae or very small regions of the tongue. 
 Smell may be, under these conditions, in great 
 measure eliminated by closing the nostrils with 
 cotton or wax, and by letting the tongue be some- 
 what advanced beyond its usual position. When 
 these conditions are observed, it is found that the 
 main sense qualities experienced are those of salt, 
 
20 THE SENSE OF TASTE 
 
 sour, sweet, and bitter, along with such touch sen- 
 sations as may be unavoidable. Temperature 
 may be eliminated by having the solutions main- 
 tained at the temperature to which the tongue is 
 already adapted. 
 
 The evidence on this point is not absolutely 
 consistent. Some observers, for example, feel 
 impelled to add metallic and alkaline to the 
 group, making six elementary qualities instead of 
 four. Other observers, — most, in fact, — are per- 
 suaded that the metallic and alkaline qualities 
 represent mixtures of the salt, sour, sweet, and 
 bitter, along with unavoidable sensations of touch 
 and smell. Thus, by a suitable mixture of strong 
 solutions of salt and sweet substances, the alka- 
 line taste may be very well produced. " It has 
 been suggested that the metallic taste is due to 
 the simultaneous development of salt and sour 
 tastes. The failure to produce exact alkaline and 
 metallic tastes synthetically is in part due to the 
 difficulty of imitating the tactual and other sensa- 
 tions with which they are bound up." Still other 
 observers are convinced by careful elimination of 
 smell sensation that the unique character of the 
 alkaline and metallic qualities is really a question 
 of odor. 
 
 By the application of specific drugs to the 
 organ of taste further indications are secured that 
 these four qualities, unanalyzable to introspec- 
 
THE QUALITIES OF TASTE 21 
 
 tion, also function in relative independence. 
 Thus, the juice of gymnema leaves temporarily 
 destroys the qualities of sweet and bitter, while 
 sensitiveness to sour and salt remains unimpaired. 
 " The true acid or sour taste may be separated 
 from the astringent effect which accompanies it 
 by painting the tongue several times with a 
 five to ten per cent solution of cocaine. Cocaine 
 first abolishes the sour taste, and after several 
 minutes begins to abolish the astringent action of 
 the acid solution. Later, the sour sensation begins 
 to return, while the astringent effect is still in abey- 
 ance, so that the application of an acid solution 
 at a certain stage during recovery enables the 
 true taste character of sour to be differentiated." 
 It is also reported that when gymnemic acid and 
 cocaine are applied to the tongue, the one abol- 
 ishes the sweet and the other the bitter, thus leav- 
 ing the two other tastes relatively unimpaired. 
 Certain mixtures seem to paralyze both sweet and 
 bitter, but the former sooner than the latter. 
 
 Distribution of the Taste Qualities 
 
 To these four elementary tastes we are 
 not equally sensitive on all parts of the sense 
 organ. Roughly speaking, sweet is best tasted 
 at the tip of the tongue, and many forms of 
 candy are prepared so as to allow as much as 
 possible the employment of this part of the taste 
 
22 THE SENSE OF TASTE 
 
 organ. Bitter, on the other hand, is best tasted 
 at the back or root of the tongue, which explains 
 why many substances do not taste bitter until we 
 have swallowed them. The edges of the tongue 
 are most sensitive to sour, while in adults the cen- 
 tral area does not commonly yield taste qualities 
 at all. In children, however, the taste buds ex- 
 tend not only over the whole surface of the 
 tongue, but are also found in the walls of the 
 cheek, the palate, and even on the larynx and 
 epiglottis. Titchener has suggested that these 
 facts may explain " the childish tendency to take 
 big mouthfuls." 
 
 Attempts have been made to determine 
 whether these elementary taste qualities depend 
 on separate taste buds or papillas. Experiments 
 show it to be true that some points respond only 
 to sweet, sour, etc. But there are others which 
 yield two or three or even all four qualities, while 
 some yield no taste at all. In one such experi- 
 ment thirty-nine papillae, in a certain region, were 
 separately stimulated by acid, sugar, salt, and 
 quinine. Of these thirty-nine, thirty-one re- 
 sponded to salt, and the same number to sweet, 
 twenty-nine to sour, twenty-one to bitter. Four 
 yielded no taste at all, one responded only to bit- 
 ter, and one to sweet. In another case of one 
 hundred and twenty-five papillae examined by 
 solutions of sugar, quinine, and tartaric acid, 
 
THE QUALITIES OF TASTE 23 
 
 sixty gave sensations of all three qualities (sweet, 
 sour, bitter), twelve gave both sweet and sour, 
 twelve sour only, seven bitter and sour, four bit- 
 ter and sweet, and three sweet only. None of 
 them seemed to give a bitter quality alone and 
 this seems to be the general rule. 
 
 It is of course difficult in these experiments to 
 restrict the application of the stimulus to single 
 taste buds or even to single papIUas. But these 
 experiments, along with the effects of drugs which 
 we have already described, suggest that the taste 
 buds are not all alike in function, even though 
 they seem quite similar so far as appearance and 
 structure are concerned. 
 
 The Vocabulary of Taste 
 
 Several investigators have been interested in 
 the study of the taste names found in different 
 languages and communities. It has been sug- 
 gested that such a study might throw light on the 
 order of development of the various taste qual- 
 ities. 
 
 Kiesow found that both children and adults 
 quite commonly confused bitter with salt and 
 sour. Myers found, in studying the taste names 
 of primitive people in the region of the Torres 
 Straits, that they had no word for bitter. In 
 some primitive languages the same word is used 
 for sweet and salt. When there is a word for 
 
24 THE SENSE OF TASTE 
 
 salt It is usually some derivative of the word for 
 sea water. Salt and sour are also often confused. 
 In Polynesia, indeed, a single word is used in de- 
 scribing salt, sour, and bitter tastes. This is 
 analogous to the fact that in primitive languages 
 it is often found that the same word is used to 
 indicate blue and black. 
 
 Attempts to argue from these facts of vocabu- 
 lary to facts of sensitiveness and order of devel- 
 opment are, of course, open to many sources of 
 error. As Myers points out, " The differences 
 between sour and bitter are considered less strik- 
 ing than their common unpalatability." It has 
 often been pointed out that in our own language 
 sweet is probably the only taste word that had 
 from its very origin a gustatory meaning. In 
 some languages even the word for sweet means 
 literally " tasting good." 
 
 Vocabularies do not develop in order that 
 structural and functional facts may be recorded 
 for the information of forthcoming scientists. 
 Words arise in response to the demands of prac- 
 tical life. It is practically more important that 
 some substances " taste good," and others " taste 
 bad," than that there are just four elementary 
 faste qualities. Hence for certain primitive cir- 
 cumstances two taste words are all that are 
 needed in oi-dinary conversation. It by no means 
 follows from this that the salt, sour, and bitter, 
 
THE QUALITIES OF TASTE 25 
 
 which all fall In the " bad taste " category, are 
 not discriminable from one another by the taste 
 organs of the savage. It would be just as cogent 
 to insist that, since we have only one word 
 for the taste of various sour things, all of 
 these various tastes must be indistinguishable 
 to us. 
 
 Nor is the argument safe that those sense qual- 
 ities for which specific names exist must be more 
 ancient than those qualities for which names are 
 borrowed. Many of our color names are not 
 primarily color names at all, — as violet, rose, 
 olive, turquoise, lemon, straw, orange, and, per- 
 haps, pink and green. Red, blue, and yellow seem 
 to be more essentially color names. Yet, it is 
 difficult to suppose that an organism sensitive to 
 red and yellow should not also be sensitive to 
 orange, which may be produced by a mixture of 
 red and yellow light. 
 
 In the case of the odors, which we have every 
 reason to believe are extremely ancient sense qual- 
 ities, we have in our own language almost no ex- 
 clusively olfactory names. Smells are designated 
 by the objects with which they are associated, — as 
 lilac, lavender, musk; or names are borrowed 
 from other sensory modes, as sweet, sour, 
 heavy; or still more descriptive and perceptual 
 names are used, such as fresh, flat, rancid, foul, 
 nauseating. Interesting as the vagaries of vocab- 
 
26 THE SENSE OF TASTE 
 
 ulary may be, they yield very little information 
 concerning the primitiveness, elementariness, sen- 
 sitiveness, or distribution of the various taste 
 qualities. 
 
CHAPTER II 
 
 The Organization of the Tastes 
 
 System and Organization in Other Senses 
 
 In the case of some of the sensory modes it is 
 possible to arrange the various elementary qual- 
 ities in a schema or graph, representing in a dia- 
 grammatic way their relations to each other, the 
 results of their combination, their influence on 
 each other, etc. 
 
 Thus, in the case of vision the conventional 
 " color pyramid " expresses the various relations 
 between the different elementary colors and the 
 different degrees of brightness. Red, yellow, 
 green, and blue occupy the corners of the base of 
 a double pyramid. The upper apex represents 
 white and the lower apex black. On the side be- 
 tween red and yellow are found the various 
 oranges which result from mixing red and yellow 
 light in varying proportions. On the remaining 
 sides are represented the combinations of yellow 
 and green, green and blue, blue and red. Along 
 the vertical axis range the different grays. Cross 
 sections of the pyramid indicate, at different 
 
 87 
 
28 THE SENSE OF TASTE 
 
 levels, the result of mixing the different colors 
 with these grays, thus yielding the tints and 
 shades of the colors. Along the base, the colors 
 which are at the extreme ends of any diagonal 
 passing through the center are complementary, — 
 they neutralize each other when mixed and under 
 other circumstances each tends to induce the other 
 by contrast. The visual manifold may thus be 
 adequately schematized on a three-dimensional 
 figure. 
 
 In a similar way the various tones, in the case 
 of hearing, may be arranged along a one-dimen- 
 sional line, which represents the tonal scale. Is 
 it possible to arrange in any such systematic way 
 the elementary taste qualities so as to indicate 
 their relationship to each other? Before sug- 
 gesting such a diagram it will be well to have in 
 mind just what relationships the various taste 
 qualities do as a matter of fact display. 
 
 Taste Mixtures and Compounds 
 
 > The testimony of daily experience would prob- 
 ably be at once that the various elementary tastes 
 may combine to produce new tastes of a more 
 complex or even of a unitary character. Thus, 
 the taste of lemonade is distinctive enough. Yet 
 even casual observation suffices to show that the 
 sweet and the sour components have by no means 
 lost their identity, since each can be singled out 
 
ORGANIZATION OF THE TASTES 29 
 
 in attention and recognized as the familiar ele- 
 mentary quality.. Red and blue may fuse to pro- 
 duce a violet or a purple from which the original 
 elements can by no means be singled out and iden- 
 tified through direct inspection. But it seems to 
 be the rule that tastes do not behave in this way, 
 although the demands of daily experience do not 
 readily lead us to discover the fact. *" Think, for 
 instance," writes Titchener, " of the flavor of a 
 ripe peach. The ethereal odor may be ruled out 
 by holding the nose. The taste components, — 
 sweet, bitter, sour, — may be identified by special 
 direction of the attention upon them. The touch 
 components — the softness and stringlness of the 
 pulp, the puckery feel of the sour — may be 
 singled out in the same way. Nevertheless, all 
 these factors blend together so intimately that it 
 is hard to give up one's belief in a peculiar and 
 unanalyzable peach flavor. Indeed, some psy- 
 cholo^sts assert that this resultant flavor exists; 
 that in all such cases the concurrence of the taste 
 qualities gives rise to a new basic or fundamental 
 taste, which serves, so to say, as background to 
 the separate components. There is, however, no 
 need to make any such assumption. It is a uni- 
 versal rule in psychology that when sense qual- 
 ities combine to form what is called a perception, 
 the result of their combination is not a sum but a 
 system, not a patchwork but a pattern. . . . 
 
30 THE SENSE OF TASTE 
 
 Hence, just as it would be absurd to say that the 
 plan of the locomotive is a new bit of steel or the 
 pattern of the carpet a new bit of colored stuff, 
 so is it wrong to say that the peach character of 
 a certain taste blend is a new taste quality." 
 
 The mixture of stimuli provoking two taste 
 qualities does not, then, produce intermediate 
 qualities such as the orange which results from 
 the mixture of red and yellow. Instead, in this 
 case, the two qualities do one of these three 
 things: (a) they may remain separate and dis- 
 tinct; (b) they may fluctuate individually and 
 alternate with each other in their appearance; (c) 
 they may tend to neutralize each other. If the 
 stimuli are very intense, oscillation is the common 
 result. If the stimuli are weak, some degree of 
 neutralization is reported to be the rule. Only 
 in one case, namely, the mixture of sweet and salt, 
 does a new taste seem to emerge, which does not 
 resemble either of the original qualities. Kiesow 
 finds that such a- mixture, in the case of weak 
 solutions, gives rise to a quality described as 
 "flat," "vapid," or " insipid,"— the alkaline 
 taste which we have already considered. 
 
 Compensation, Antagonism, and Neutralization 
 
 In the case of color, there may be found for 
 every quality or mixture an opposite quality or 
 mixture which when combined with the former 
 
ORGANIZATION OF THE TASTES 31 
 
 either completely neutralizes it or at least reduces 
 its intensity. Thus blue and yellow, of the proper 
 tones and proportion, cancel each other, leaving 
 only an experience of gray. So do a certain olive 
 color and a particular violet, a certain orange and 
 a particular bluish-green, a certain red and a par- 
 ticular green. 
 
 We have already suggested that in case of 
 weak taste qualities a similar effect is present. 
 " With the low intensities there is in most cases 
 a partial compensation, which is least for sweet 
 and sour, better for salt and bitter, better still for 
 sour and bitter, sour and salt, sweet and bitter." 
 These facts are utilized in daily life in the count- 
 less combinations , of dressings, sauces, seasonings 
 and condiments used in the preparation of food. 
 We take sugar with our tea, our coffee, our choco- 
 late, our strawberries, our grapefruit, and our 
 lemon juice, and realize that it to some degree 
 counteracts or neutralizes the bitter or the sour 
 taste of these foods in their original form. " Salt 
 corrects the sweetness of an over-ripe melon." 
 In our salad dressings, sauces, gravies, relishes, 
 and bitters we find the means of reenforcing or 
 toning down the taste qualities to suit our own 
 particular fancy. 
 
 In part, of course, these effects are not achieved 
 through the mere process of neutralization. The 
 addition of touch qualities, such as the pucker of 
 
32 THE SENSE OF TASTE 
 
 vinegar, the sting of pepper, the bite of mustard, 
 and the burn of onion, plays its own part in the 
 constitution of a flavor, regardless of their com- 
 pensating influence on the pure taste qualities, 
 f In line with the fact that taste and odor are 
 easily confused, and contributing perhaps to this 
 confusion, is the fact that tastes and odors are 
 related to each other through their antagonism, 
 almost if not quite as definitely as are the qualities 
 within each of the separate modes. Thus, the 
 sickening odor of many medicines is somewhat 
 palliated if they are taken in fermented juices or 
 with the sour acids of fresh fruits. " Quinine, 
 which tastes bitter and has no smell, is corrected 
 by essence of orange peel, which has an aromatic 
 smell and no taste." Titchener pertinently re- 
 marks that these results may in part arise from 
 the simple process of distracting attention from 
 an unpleasant item to a more agreeable part of 
 the experience. On the other hand, the special 
 effectiveness of the introduction of odors into the 
 complex rather than pleasant sights and sounds 
 suggests that the results in the case of taste and 
 smell are not solely a matter of attention, but 
 are in part, at least, dependent on the essential 
 relationships between the qualities of these two 
 modes of sensation.^ In the chapter on " The 
 Evolution of Taste " certain light is thrown on 
 the_ d9^eness of these relationships by our krjowl- 
 
ORGANIZATION OF THE TASTES 33 
 
 edge of the intimate biological connection be- 
 tween taste and smelL^ In certain lower forms of 
 animal life it is indeed quite impossible to draw 
 any clear line between these two features of " the 
 chemical sense." 
 
 In general, then, although the facts of compen- 
 sation, antagonism, and complementariness are 
 to be observed within the field of the taste qual- 
 itiesi the relations disclosed are by no means as 
 definite nor as systematic as they are in the case 
 of vision. For a given primary color quality 
 there exists only one other elementary quality 
 which stands to it in the relation of antagonist. 
 But we have seen that in the cases of both sour 
 and bitter there is at least some degree of an- 
 tagonism with all three of the other qualities, 
 while both sweet and salt antagonize in some de- 
 gree both sour and bitter. Moreover, at least 
 the sour, the bitter, and the sweet appear to 
 show antagonistic relations to certain qualities of 
 smell. 
 
 In none of these cases has there been presented 
 clear evidence showing the ability of one quality 
 to totally efface another, so that no taste what- 
 ever is present. In the case of colors, however, 
 the result of such combinations in the right pro- 
 portions may easily be a total absence of color 
 quality. It is true that occasional instances of 
 such effects in taste have been reported, but the 
 
34 THE SENSE OF TASTE 
 
 general rule seems to be that the extreme degree 
 of neutralization leaves an experience which is 
 recognized as a taste, but which is described as 
 " flat " or as " insipid." It is possible, of course, 
 that this " insipid" taste quality is the tactile and 
 kinaesthetic residue of the total experience, much 
 as the " gray " which results from the combina- 
 tion of complementary colors may be described 
 as the brightness residue of the total momentary 
 effect. But in the latter case the residue would 
 be distinctly " visual " although not " color." In 
 the case of taste nothing corresponding to the 
 " brightness " of vision is recognized, and the 
 residue as we have described it would - con- 
 sequently belong to a different mode of sensation. 
 
 Contrast Phenomena 
 
 The phenomena known as contrast are very 
 familiar sense experiences. Not only is it true 
 that in the fields of perception and feeling the tall, 
 the good, the wholesome, the fast, the daring, and 
 the pleasant have their qualities enhanced when 
 they accompany or follow upon the diminutive, 
 the wicked, the foul, the slow, the cowardly, and 
 the disagreeable; in the case of more simple 
 sense experiences also contrast effects are often 
 both immediate and striking. The apparent tem- 
 perature of the air or water varies with the con- 
 ditions from which we emerge into them. The 
 
ORGANIZATION OF THE TASTES 35 
 
 sudden calm after a thunderstorm seems even 
 more empty than the same conditions in Indian 
 summer. The palest complexion assumes a 
 moderate rosiness if green ribbons and fabrics are 
 suitably arranged about or near it. Even a pure 
 gray strip of paper becomes a rich pink line or a 
 yellowish band when placed across a background 
 of saturated green or blue. 
 
 Daily experience entails many such instances of 
 contrast in the case of the taste qualities as well. 
 A ripe apple may surprise us by its unexpected 
 sourness if we come to it direct from a box of 
 bonbons. Experiments designed to investigate 
 the presence and character of taste contrasts are 
 especially interesting and their results are in many 
 ways curious. If, under proper experimental pre- 
 cautions, a salt solution is applied to one side of 
 the tongue and a drop of tasteless distilled water 
 is simultaneously applied to the other side, the 
 tasteless water is reported as sweetish. If, in- 
 stead of the distilled water, one apply a sugar 
 solution of such weakness that its taste could not 
 under ordinary circumstances be recognized, the 
 sweetness becomes clearly apparent. Under the 
 same circumstances a solution otherwise produc- 
 ing a weak sensation of sweetness is reported as 
 being " very sweet." The salt solution, that is 
 to say, induces by contrast the quality of sweet- 
 ness in tasteless substances and enhances the de- 
 
36 THE SENSE OF TASTE 
 
 gree of an otherwise weak quality aroused at 
 another region of the tongue. 
 
 In much the same way a sugar solution induces 
 saltiness, or sourness, or perhaps bitterness, ac- 
 cording to the individual, the occasion, and the 
 circumstances. Sometimes the salt induces a sour 
 instead of the sweet. The bitter, however, seems 
 unable to induce other qualities by contrast, and 
 is at least seldom induced by the other qualities. 
 
 In this as in other respects the bitter quality 
 seems to show idiosyncrasies. Thus, it is gen- 
 erally accepted that no papillas are ever sensitive 
 only to bitter stimuli. Many primitive languages 
 are said to contain in their vocabulary no word 
 for bitter : it is not uncommon in daily experience 
 to find bitter confused with sour; bitter seems to 
 be especially easily antagonized by certain odors ; 
 it does not display striking contrast phenomena; 
 and its reaction time is exceptionally slow. 
 <^he type of contrast which we have thus de- 
 scribed in the case of the tastes is known as simul- 
 taneous contrast Both stimuli are applied at the 
 same time to different parts of the sense organ. 
 What is known as successive contrast can also be 
 experimentally produced. Here one of the 
 stimuli follows the other after an interval in 
 which nothing is applied or, still better, in which 
 the mouth is carefully rinsed with water. This 
 is the type of taste contrast with which we are 
 
ORGANIZATION OF THE TASTES 37 
 
 most familiar in daily life. The same contrasts 
 may be induced experimentally by this method as 
 result from the simultaneous method. But the 
 inducing stimuli in this case must be rather more 
 intense than is necessary for the production of 
 simultaneous contrasts. In much the same way in 
 perception as in sensation the contrast between 
 two extremes or opposites is better realized when 
 both are present together than when one follows 
 the other after an interval. 
 
 The general facts of taste contrast are suc- 
 cinctly summarized by Titchener in the following 
 way: 
 
 / (i) Salt and sour contrast: the sour induced 
 by salt being clearer and stronger than the salt 
 induced by sour. 
 
 (2) Sweet and sour contrast: the sweet in- 
 duced by sour being clearer and stronger than the 
 sour induced by sweet. 
 
 (3) Salt and sweet contrast: the sweet induced 
 by salt being clearer and stronger than the salt 
 induced by sweet. 
 
 (4) Bitter shows no contrast at all. 
 
 (5) The order of qualities, as regards ease of 
 induction, is sweet, sour, salt, bitter. 
 
 After Images of Taste 
 
 Suggested by the phenomena of contrast are 
 the somewhat related facts of after sensations or 
 
38 THE SENSE OF TASTE 
 
 after-images, as they are sometimes called. When 
 one looks for a moment at a candle or other 
 source of light and then quickly extinguishes it 
 or looks away from it, one still continues to see, 
 for a time, a luminous form, which may persist 
 for a considerable time after the removal of the 
 stimulus. In such a case the color and brightness 
 of this after image may be the same as those of 
 the original object, and the after image is hence 
 said to be positive. Under certain conditions the 
 colors of the after image are complementary to 
 those of the original and the brightness relations 
 of the various parts are reversed. The after 
 image is then said to be negative. Or if after 
 looking at a colored object one transfers his gaze 
 to a gray expanse there appears upon this gray 
 field an outline of the original object, with colors 
 which are complementary or antagonistic to those 
 of the original. After sensations of pressure 
 arising under special conditions have been de- 
 scribed, and positive after effects of warm and 
 cold stimuli seem also to be demonstrable. Even 
 after sensations of sound, somewhat weak, transi- 
 tory, and by no means easily detected, have been 
 described. In all these cases except vision the 
 after sensations are of the positive type only. 
 
 In the case of taste, and of smell also, it is diffi- 
 cult to investigate the presence of such after sen- 
 sations, inasmuch as it is by no means easy to be 
 
ORGANIZATION OF THE TASTES 39 
 
 sure that some trace of the stimulus does not re- 
 main in or near the sense organ. An experience 
 reported as a positive after sensation might easily 
 enough represent only the effect of persistent 
 stimulation by these traces of the substance. At 
 least one investigator is convinced that in his ob- 
 servations of taste experiences " the sensation 
 continued after the tongue was so carefully dried 
 off that no particles of the tastable substance 
 were left." Similarly, experiences of tastes being 
 " left in the mouth " are very common. But our 
 inadequate control over the disposition of the 
 sapid substance and the complicated chemical re- 
 lation which exists between various substances and 
 between some substances and the natural juices 
 secreted in the vicinity of the taste organ makes 
 it impossible to assert with certainty either the 
 presence or the absence of after sensations of 
 taste. 
 
 The Schema of Taste Relations 
 The foregoing facts concerning the phenomena 
 of mixture, fusion, antagonism, contrast, and 
 after sensation show at once the impossibility, in 
 our present state of knowledge, of arranging the 
 taste qualities in any such systematic scheme as is 
 represented by the color pyramid and the tonal 
 scale in the cases of vision and hearing. It by 
 no means follows, however, that such orderly 
 arrangements have not been attempted. 
 
40 
 
 THE SENSE OF TASTE 
 
 Kiesow, one of the most famous students of the 
 sense of taste, proposed that a circle with a verti- 
 cal and a horizontal diameter indicated would 
 best represent the various relations between the 
 taste qualities. At top and bottom would stand 
 
 SALT. 
 
 BITTER^ Sn^ 
 
 SOUR, 
 
 Fig. I 
 
 salt and sweet; to left and right, bitter and sour. 
 Along the horizontal diameter would be placed 
 the mixtures of bitter and sour, and along the 
 vertical diameter would range the various results 
 of mixing salt and sweet. The mixtures of salt- 
 sour, sweet-sour, bitter-sweet, and bitter-salt 
 would stand in their appropriate places about the 
 circumference or periphery of the circle. 
 
ORGANIZATION OF THE TASTES 41 
 
 Wundt tentatively adopts a similar scheme 
 when he says : " The system of taste sensations 
 is, accordingly, in all probability to be regarded 
 as a two-dimensional continuity, which may be 
 geometrically represented by a rectangular sur- 
 face at the angles of which the four primary qual- 
 ities are placed, the various mixed qualities being 
 placed along the side and on the inner surface." 
 
 To such suggestions, however, Kuelpe objects 
 that: "There is no indication of a continuous 
 transition between the four qualities which tastes 
 appear to present, as there is between the qual- 
 ities of tone sensations. They form, not a one- 
 dimensional manifold, but a discrete system of 
 unknown relations." 
 
 Titchener, one of the most careful students of 
 sense experience, is less emphatic, but he " doubts 
 whether, in the present state of our knowledge, 
 this idea (that of Wundt) can be accepted." He 
 doubts " whether the sweet-sour of lemonade 
 stands to its originals as blue-green stands to blue 
 and green, or as orange to red and yellow; and 
 also whether bitter should lie in the same plane 
 with the other three taste qualities. We must sus- 
 pend judgment; in the meantime, Kiesow's figure 
 provides us with a working hypothesis." 
 
 Ladd and Woodworth align themselves with 
 Kuelpe and conclude that, " there is no clear in- 
 dication that the tastes can be arranged in a linear 
 
42 THE SENSE OF TASTE 
 
 scale, as the primary colors are, nor that any taste 
 stands to any other definitely in the relation of 
 opposite or complementary. On the whole it ap- 
 pears as if the four tastes were rather isolated 
 from each other, each representing almost an 
 independent sense." 
 
CHAPTER III 
 
 The Sensitiveness of Taste 
 
 Furious Measures of Sensitiveness 
 
 In a general way it is well known that exceed- 
 ingly weak solutions of many substances are suffi- 
 cient to provoke sensations of taste. It is also 
 known that weak tastes which some individuals 
 are able to detect or to recognize correctly go 
 quite unobserved by others. The same thing is 
 true of differences between tastes. The connois- 
 seur is sensitive to minute differences in the flavor 
 of wine, tobaccos, and sauces. Through practice 
 the expert taster of these substances acquires a 
 skill which is quite incomprehensible to the inex- 
 perienced. In part only is such skill a matter of 
 special sensory activity. It is in large measure a 
 matter of perception rather than one of sensation, 
 — a knowledge of what signs to look for and how 
 to interpret these signs, — rather than an increased 
 sensitiveness to stimuli. In the same way the 
 skilled gardener, hunter, or scout is alert to the 
 significance of particular signs and clues and this 
 alertness and apt interpretation may make him 
 
 43 
 
44 THE SENSE OF TASTE 
 
 appear to have senses of exceeding acuteness, 
 although this may* by no means be borne out by 
 actual measurements. 
 
 The psychological problems involved in the 
 measurement of keenness of taste are mainly two 
 in number. One problem concerns itself with the 
 question, What is the faintest stimulus that can 
 be sensed,— the weakest taste that can be appre- 
 ciated? The other concerns itself with the sensi- 
 tivity to difference between tastes, and would be 
 expressed by some such question as. How slight 
 a change in the amount or intensity of the stimu- 
 lus is required for one to be able to perceive a 
 change in the intensity of the taste sensation? 
 
 Unfortunately for our knowledge of tastes, 
 both these problems are very difficult to approach 
 experimentally. Whether or not a given weak 
 stimulus will provoke a taste sensation depends 
 on very many things other than the strength of 
 the solution. The amount of solution applied, 
 the extent of surface excited, the duration of the 
 application, the temperature of the solution, the 
 state of rest or movement of the sense organ, and 
 the nature of preceding stimuli, among other 
 things, are important. 
 
 The Threshold of Taste Sensation 
 
 Numerous investigations have concerned them- 
 selves with the task of discovering the weakest 
 
SENSITIVENESS OF TASTE 45 
 
 solution of various substances that will provoke 
 their respective sensory qualities. The main re- 
 sults of these studies have been the deihonstra- 
 tion of two facts^ namely, that exceedingly weak 
 stimuli may arouse sensations of taste and that 
 this minimum solution varies greatly in amount 
 according to the substance which is in question. 
 
 Valentin, in 1842, measured the lower thresh- 
 old for solutions of sugar, salt, quinine, and sul- 
 phuric acid and found the following proportions 
 to represent the least amounts able to arouse the 
 corresponding sensation : 
 
 Sugar i.20oparts to 100 parts of water 
 
 Salt 0.300 " " " " " " 
 
 Acid o.ooi " " " " " " 
 
 Quinine.... 0.003 " " " " " " 
 
 Numerous other investigators have reported 
 figures of this character. Thus, Nichols and 
 Bailey give the following as averages of the lower 
 thresholds in the case of measurements on forty- 
 six women: 
 
 Sugar I part to 204 parts water 
 
 Salt I "part to 2,000 parts water 
 
 Acid I part to 3,300 parts water 
 
 Bitter i part to 456,000 parts water 
 
 It is neither profitable nor interesting to draw 
 close comparisons between the various sets of 
 
46 THE SENSE OF TASTE 
 
 measures, since they vary considerably with the 
 substance used, and since, after all, as one writer 
 remarks, " the experiments are chiefly valuable 
 as gratifying our curiosity." Various students of 
 individual differences have sought to determine 
 the presence of sex differences, age differences, 
 race and group differences, in these minimal taste 
 stimuli. But the incidental factors are so numer- 
 ous and so beyond experimental control that, if 
 such differences exist, it has never been pos- 
 sible consistently to demonstrate their nature or 
 amount. 
 
 Relative Sensitivity of Taste and Smell. 
 
 A recent investigation by Parker and Stabler 
 was directed toward a question which possesses 
 a certain interest. Reasoning that, since taste and 
 smell are both " chemical " senses, it might be 
 possible to compare their respective sensitivities- 
 in terms of the strength of solution required to 
 affect them both, they attempted to make such 
 comparison in the case of one substance. Pure 
 ethyl alcohol is a substance which "has both a dis- 
 tinctive taste and a distinctive odor. These in- 
 vestigators found that the minimum amount of 
 this substance that could be sensed by taste was 
 24,000 times as great as the least amount that 
 could be detected by odor. 
 
SENSITIVENESS OF TASTE 47 
 
 The Discrimination of Tastes 
 
 In the case of our second general question, that 
 concerning the amount of change in the strength 
 of solution required to produce a felt difference 
 in the intensity of the taste sensation, various dif- 
 ficulties are involved. In the first place, there is 
 no known way of measuring the intensity of that 
 mode of stimulation which may be responsible 
 for the excitation of the taste bud. In such cases 
 as the sensibility to weight and light it is easily 
 possible to measure the intensity of the stimulus 
 in terms of pounds, candle power, or similar 
 physical units. In the cases of temperature and 
 sound the problem is much more difficult, since 
 we do not know precisely what aspect of the 
 stimulus should be used as indicating the intensity 
 of the process at the point of stimulation. Taste 
 and smell offer still greater difficulties, inasmuch 
 as we do not know even with moderate certainty 
 the real nature of the stimulation, — whether, for 
 example, it be mechanical or chemical, or both. 
 Consequently, although it is possible to state that 
 in general a change in the stimulus intensity re- 
 quired to produce a sensation, change which will 
 be correctly reported in a certain percentage of 
 the trials is 1^ for light, 33^ for sound, 5J^ for 
 lifted weights, no such coefficients of change can 
 even be suggested for taste and smell. Only the 
 
48 THE SENSE OF TASTE 
 
 general statement can be made that, within limits^ 
 increased strength of solution means increased 
 intensity of sensation. 
 
 Adaptation and Fatigue 
 
 Curious phenomena in the case of all the senses 
 are those known as adaptation and fatigue. It 
 is a familiar experience that the illumination of 
 a room which seems upon entrance to be yellowish 
 quickly comes to appear merely light. After a 
 few minutes wearing colored goggles the tinge 
 they give to objects seems to disappear and we 
 say we have become " adapted " to the color. 
 " We become rapidly adapted to a constant stimu- 
 lus so that we fail to notice the weight of our 
 hats, the temperature of the room we are in, the 
 odors of the subway." Searching for spectacles 
 which meanwhile perch upon the nose is the result 
 of adaptation. A related phenomenon is the fact 
 that a darkened room which on entrance seems 
 perfectly black comes in time to show its contents 
 as more or less clearly marked off from one an- 
 other. 
 
 Some adjustment — in the sense organs, per- 
 haps, or perhaps in the brain centers — takes 
 place in the presence of a constant stimulus. The 
 general result of this adjustment is that the par- 
 ticular sense quality involved fades away: colors 
 tend toward gray, pressures tend to disappear, 
 
SENSITIVENESS OF TASTE 49 
 
 temperatures tend toward a neutral point, and 
 sounds become indifferent. This adjustment is 
 not fatigue in the usual sense of the word. The 
 area that has become adapted to a given pressure 
 is still sensitive and will feel even a lighter weight 
 if this be substituted for the one to which it has 
 become adapted. It is adapted to a continuous 
 stimulus, but it is sensitive to any change in the 
 stimulus. 
 
 In the case of smell it is notorious that odors 
 constantly present soon cease to be observed or 
 even to be observable. Even the most disagree- 
 able and insistent odors fade away in time. In a 
 few minutes stale cheese comes to have no dis- 
 cernible odor, while the odors of tobacco smoke 
 and various perfumes disappear equally quickly. 
 In this sense adaptation seems to be much more 
 like exhaustion or fatigue than in the cases of 
 sound, sight, and pressure, and it may require a 
 considerable interval of freedom from the stimu- 
 lus before the quality returns. 
 
 The laws and effects of adaptation are by no 
 means the same for all the senses. Thus, in the 
 case of smell, adaptation to certain odors seems 
 to increase our sensitivity to other odors. In the 
 case of taste the effects are by no means clear nor 
 consistently reported by different observers. In 
 general it seems to be true that the effect of 
 adaptation to a given taste quality has no 
 
so THE SENSE OF TASTE 
 
 demonstrable effect on the remaining qualities, 
 and that this effect, as in the case of smell, is of 
 the general character of exhaustion. Taste, along 
 with smell, seems to have not yet developed any 
 peripheral or central mechanism whereby adapta- 
 tion may take place without actual loss of sensi- 
 bility. 
 
 Acquired Tastes 
 
 In a very different sense the word " adapta- 
 tion " is often employed to express the phe- 
 nomenon of habituation in the case of " acquired 
 tastes." Here the habituation is not to the taste 
 quality,' in a sensory sense, but represents a 
 change in the feeling or affective tone which char- 
 acterizes or accompanies this quality. 
 
 The easier case to understand is that in which 
 the continued indulgence in a substance, such as 
 ice cream, candy, tobacco, sets up organic effects 
 which have their unpleasant accompaniment. 
 Here it happens that a taste originally very pleas- 
 ant becomes indifferent or even disgusting. The 
 unpleasantness in such a case is rather easily seen 
 to arise, not from a taste quality alone, but from 
 the total state of the moment. On a later occa- 
 sion the first appearance of the taste quality 
 may, by well-recognized associative mechaniisms, 
 arouse the organic revulsions or memories of 
 them, with the attendant disagreeable effect. The 
 
SENSITIVENESS OF TASTE 51 
 
 originally agreeable taste then appears to have 
 become disagreeable. 
 
 Cases of the reverse order are equally familiar, 
 in which a taste originally unpleasant comes, with 
 repetition, to lose its disagreeable character, or 
 even to become distinctly pleasing. Indeed, in 
 many such cases habituation results in the estab- 
 lishment of a craving for the quality which was 
 originally repulsive. Here the repetition of the 
 taste quality seems to set up defensive adjust- 
 ments and adaptations of a profound organic 
 kind rather than the earlier protective reactions 
 of refusal and rejection. Once this adjustment 
 or adaptation takes place the presence of the 
 original stimulus is called for as part of the new 
 condition of balance, and the craving, or appetite, 
 results. In this account, it must be confessed, we 
 speak in terms of vague generalities, since it is 
 not easy to state the precise nature of these bio- 
 logical adaptations. But their existence in the 
 case of many users of such things as olives, garlic, 
 tobacco, liquors, and various drugs is a matter 
 of common experience. 
 
 The Early Development of Taste 
 
 In the chapter on " The Evolution of Taste " 
 it will be shown that very early in the develop- 
 ment of the forms of animal life there is present 
 a form of sensibility to that type of stimulation 
 
52 THE SENSE OF TASTE 
 
 which, in our own experience, provokes sensations 
 of taste. The " chemical " sense is thus seen to 
 be a very primitive mode, and adjustments to 
 chemical factors in the environment are present 
 at a very low level of organic development. It 
 is a general rule that capacities which appear thus 
 early in the animal series (phylogeny) also ap- 
 pear relatively early and relatively complete in 
 the development of the individual (ontogeny) of 
 more elaborate forms. So far as we are able to 
 discover, this rule holds for the development of 
 the sense of taste. In a number of cases indi- 
 vidual infants have been carefully observed in 
 order to note the order of development of the 
 various senses and the adjustments to stimuli in 
 these different modes. In several cases large 
 numbers of newborn infants have been tested im- 
 mediately after birth, with the same questions in 
 mind. 
 
 These studies show that not only is sensibility 
 to taste present at the time of birth, but that the 
 newborn infant reacts in different ways to the 
 various taste qualities. On the first experimental 
 application of taste stimuli distinguishable reac- 
 tions, such as quiet sucking, grimacing, nausea 
 movements, facial expressions, and varied mi- 
 metic behavior, indicate that at least in a rudi- 
 mentary way the various taste qualities are 
 
SENSITIVENESS OF TASTE 53 
 
 responded to in a selective or discriminative 
 manner. 
 
 Thus, Kussmaul, in 1859, tested twenty-one 
 children with solutions of sugar and of sulphate 
 of quinine. In general the sweet and the bitter 
 caused " the same mimetic facial movements as 
 are observed in adults." There seemed, how- 
 ever, to be certain individual differences in sensi- 
 tivity, and occasionally sweet and bitter provoked 
 facial reactions which were not distinguishable. 
 Guezer, in 1873, studied fifty newborn infants by 
 giving them tastes of sugar, quinine, and weak 
 acetic acid. The sugar, as a rule, produced 
 " pleasurable sucking," the quinine and acid pro- 
 duced " unpleasant ' bitter ' expression and even 
 nausea movements." Kroner, in 1882, recorded 
 studies of the taste reactions of his own children 
 at birth. He observed that they reacted imme- 
 diately after birth to sweet and bitter with the 
 characteristic facial expression of the adult. He 
 was convinced that the sense of taste was at birth 
 the best developed of all the senses. 
 
 The most elaborate study of this kind yet 
 recorded is that of Peterson and Rainey. These 
 observers report tests of 1,060 newborn infants, 
 varying in nationality, color, sex, and period of 
 gestation. The experiments included tests on all 
 the senses. As taste stimuli for salt, sour, sweet, 
 and bitter they employed solutions of salt, acetic 
 
54 THE SENSE OF TASTE 
 
 acid, simple syrup, and tincture of gentian. The 
 tests of taste showed " with great regularity 
 mimetic reactions to these stimuli characteristic 
 of adults, grimaces of discomfort, or expressions 
 of content and lilcing." "The gustatory nerve 
 not only reacts differently to salt, sweet, bitter, 
 and sour at birth, but the same mimetic reactions 
 are observed in premature infants. This nerve 
 is therefore ready to receive taste impressions 
 some time before the normal period of birth." 
 
CHAPTER IV 
 
 Time Relations of Taste Qualities 
 
 The Inertia of this Taste Organs 
 
 Many experiments have been undertaken in the 
 effort to measure the inertia or sluggishness of 
 the various senses. Inasmuch as the nervous 
 structure is a physical system set in operation by 
 the incidence upon it of external agencies, in each 
 of its parts it requires a certain time in order to 
 be set going; and, once set in operation, acquires 
 a certain momentum which necessitates that a 
 certain time elapse before it is again in a state of 
 equilibrium. At least the sense organs all show 
 such inertia, so that, in a g^ven case, only a limited 
 number of distinct sensations can be produced in 
 a given time by successive stimulation. A meas- 
 ure that has often been used for expressing such 
 facts is the maximum number of separate excita- 
 tions to which the sense organ responds in a unit 
 of time, as one second. This measure, to be sure, 
 varies considerably with numerous conditions and 
 circumstances, such as the nature of the stimulus, 
 the part of the sense organ affected, its previous 
 
 55 
 
S6 THE SENSE OF TASTE 
 
 condition, the intensity of the stimulation, etc. 
 This measure, which may be said roughly to indi- 
 cate the duration of a sensation (including its 
 positive after image), is very short for touch, 
 somewhat longer for sound, and still longer for 
 vision. Because of the nature of the stimuli in 
 taste and smell and the difficulty of accurately 
 controlling their application and removal, satis- 
 factory measures of the inertia of these sense 
 organs have never been secured. 
 
 Reaction Time to Taste Stimuli 
 
 One fact, however, seems to be fairly clear 
 from experiment, although it would by no means 
 be suspected from casual observation, namely, 
 that the various taste qualities are not equally 
 prompt in the time required for them to appear 
 after the application of the stimulus. Salt and 
 sweet come rather quickly as compared with sour 
 and bitter, the order of speed being salt, sweet, 
 sour, bitter. How much this may depend merely 
 on such differences as may exist in the structure 
 and location of the various taste buds it is impos- 
 sible to say. Kiesow points out that taste sensa- 
 tions are tardy and gradual in their appearance. 
 If the person being stimulated be required to 
 indicate by a signal the instant at which the taste 
 quality appears, it is possible to measure, in very 
 small units of time, the interval between the 
 
RELATIONS OF TASTE QUALITIES 57 
 
 superficial application of the solution and the ap- 
 pearance of the sensation. This is called the 
 " reaction time " to the taste stimulus. When 
 the stimuli were applied to the tip of the tongue 
 Kiesow found the following figures to represent 
 average reaction times to his different solutions: 
 
 Salt 307 seconds 
 
 Sweet 446 " 
 
 Sour 536 " 
 
 Bitter 1.082 " 
 
 The reaction to bitter, which requires twice as 
 long in the above case as that of any other qual- 
 ity, was considerably shorter when the stimulus 
 was applied to the root of the tongue. This sug- 
 gests that the differences found by Kiesow may 
 in part, at least, depend on the accessibility and 
 perhaps also on the number of such various types 
 of taste buds as there may be. 
 
 Taking these reactions times as they stand, the 
 average time for the four taste qualities may be 
 said to be about one-half a second. As compared 
 with the reaction times of other sense modes, 
 taste is more sluggish than any other sense, with 
 the possible exception of smell. Averaging the 
 results of numerous observers for the range of 
 stimulus qualities and intensities that have been 
 employed, the comparative times are somewhat 
 as follows: 
 
58 THE SENSE OF TASTE 
 
 Reaction to sound. . . 
 
 .146 second 
 
 " touch... 
 
 .149 
 
 " sight... 
 
 .189 
 
 " taste.... 
 
 .500 (?) " 
 
 " smell.... 
 
 .500 (?) " 
 
 It should, of course, be borne in mind that these 
 are but averages of figures which vary consider- 
 ably with a large number of factors, although it 
 is true that the influence of these factors can itself 
 be subjected to precise measurement. 
 
 Determinants of Reaction Time to Taste 
 
 By way of illustration of the numerous inci- 
 dental and extraneous factors that influence reac- 
 tion time to the taste qualities we may instance 
 the temperature of the solution. In what seems 
 to have been a carefully conducted series of ob- 
 servations Chinaglea has recently shown the na- 
 ture of this influence. As Kiesow had already 
 found, the temperature of the solution (within 
 the pain limits) does not influence the intensity of 
 stimulus required to produce the weakest sensa- 
 tion, and hence does not modify the threshold or 
 limen. But such changes Chinaglea showed to 
 have a measurable influence on the reaction time 
 to taste stimuli. Lowering the temperature of 
 the solution below that of the mouth does not 
 affect reaction time to salt, but it lengthens the 
 
RELATIONS OF TASTE QUALITIES 59 
 
 time for the other qualities. Raising the tem- 
 perature of the solution above that of the mouth 
 quickens the reaction to sweet, but lengthens the 
 reaction to bitter and sour. 
 
CHAPTER V 
 The Sense Organ of Taste 
 
 Comparison With Other Sense Organs 
 
 The so-called higher senses are usually dif- 
 ferentiated from the lower on the basis of their 
 greater intellectual value. The sense of taste is 
 one of the lower, as compared with vision and 
 hearing, which are of the higher group. Not 
 only in the purpose which they serve, but also in 
 the character of their mechanism, do the senses 
 differ. The sense of taste differs from the sense 
 of sight in at least three respects. First, it is a 
 mechanism not given over exclusively to the taste 
 function, but serves other functions as well. The 
 visual mechanism, for instance, is very highly 
 specialized. It consists of an elaborate mechani- 
 cal device, — extrinsic and intrinsic muscles, lens, 
 iris, etc., — ^which serves to prepare the physical 
 stimulus to act upon the real receptor portion of 
 the sense organ, the retina. None of these parts 
 of the eye serve any other purpose than that of 
 vision. In the case of the taste mechanism, on 
 
 60 
 
THE SENSE ORGAN OF TASTE 6i 
 
 the other hand, only the receptor * portion of 
 the mechanism is concerned exclusively in the 
 taste function. The tongue, usually considered the 
 most important part of the taste organ, with its 
 great variety of movements, is a very necessary 
 part of the speech mechanism. The salivary 
 glands, which by their secretions put the sub- 
 stances entering the mouth into such condition 
 that they may act upon the receptor mechanism, 
 are of vital importance for the process of diges- 
 tion. The small receptors imbedded within the 
 coverings of the tongue and the linings of the 
 mouth cavity may be considered as the only 
 structures Ivhich perform exclusively a taste 
 function. 
 
 Secondly, it is not easy to determine the limits 
 of distribution of the receptor organs of taste, 
 as one can do in the case of the eye, with its 
 clearly defined retina, or the ear, with its organ 
 of Corti, or even the nose, with its regia 
 olfactoria fpatch of mucous membrane). That 
 is, there is no one organ with its attach- 
 ments which can be called the taste organ. 
 Consequently, one does not find any general 
 agreement as to what structures ought to be in- 
 cluded in the taste mechanism. For Instance, it 
 
 *A receptor is the part of the sense organ in which the 
 transformation from a physical stimulus to a nerve impulse 
 occurs. 
 
62 THE SENSE OF TASTE 
 
 is well known that the taste function is not limited 
 to the tongue, and that the whole mouth cavity 
 is a more or less important part of the taste 
 mechanism. Certain investigators are not willing 
 to circumscribe the taste organ within such nar- 
 row limits, but extend it to the larynx, the vocal 
 cords, and some have even gone so far as to in- 
 clude the membranes of the nasal cavity. 
 
 Finally, the taste mechanism is extremely simple 
 when compared with the so-called higher senses, 
 especially that portion of it whose function is to 
 prepare the stimuli to act upon the receiving 
 mechanism. The taste organ is generally be- 
 lieved to represent a stage in evolution very near 
 to the original structures from which all of the 
 sense organs have developed. That is, looked at 
 from the evolutionary point of view, it is a more 
 primitive and less highly developed mechanism. 
 
 The Salivary Glands and Their Activity 
 
 Consider first those portions of the taste organ 
 which perform the mechanical function of pre- 
 paring the stimulus to act upon the receiving 
 mechanism or the sensory ends of taste. Most 
 important of these are the salivary glands and 
 the tongue. The latter through its movements, 
 facilitates contact of the taste substances with the 
 sensory ends of taste, and the former secrete 
 saliva, which dissolves the sapid substances, re- 
 
THE SENSE ORGAN OF TASTE 63 
 
 ducing them to the liquid form necessary for 
 arousing taste sensations. 
 
 The salivary glands and their secretions are of 
 interest to the student of taste only in so far as 
 their activity forms a necessary step in the taste 
 process. In this connection it must be remem- 
 bered that the chief function of the saliva is the 
 part it plays in the process of digestion. As sug- 
 gested above, the function of the saliva in the 
 taste process is merely that of dissolving or trans- 
 forming solids into liquid form. Consequently, 
 the chemical constitution of the saliva and the de- 
 tailed structure of the glands are aside from our 
 interest. The action of these glands, three in 
 number, and called the parotid, the submaxillary, 
 and the sublingual, is of the reflex type. The 
 stimuli for the reflex are numerous, and, it ap- 
 pears, are not the same for all of the glands. For 
 instance, the submaxillary glands are said to 
 secrete upon the presence of certain foods, acids 
 in the mouth, the chewing of meats, etc. On the 
 other hand, the stimulus for the parotid gland has 
 been shown by Pavlow to be the presence of dry 
 substances in the mouth. If no distinction is made 
 between glands. It may be said that watery foods 
 cause only a slight flow of saliva, while dry foods 
 cause a large flow of saliva. One sees, then, a 
 set of reflexes which not only promote the diges- 
 tion of foods, but which also tend to make therp 
 
64 THE SENSE OF TASTE 
 
 tastable. These two functions are not entirely 
 separate ones, for it has been shown by experi- 
 ment that the tastes of various foods are deter- 
 mining factors in causing and regulating the flow 
 of gastric juice in the stomach. 
 
 Although the action of the glands is reflex in 
 character, and is due to the stimulation, by objects 
 in the mouth, of the glossopharyngeal and lingual 
 nerves supplying the mouth and tongue, this is 
 not the only means by which the reflex can be ex; 
 cited, or the flow of saliva produced. It is a mat- 
 ter of common knowledge that the sight of vari- 
 ous objects — a lemon, for instance — will cause a 
 copious flow of saliva, and, further, that certain 
 mental states, such as fear, anxiety, and the like, 
 may cause reduction of the flow of saliva, with 
 the resultant dry mouth, the cleaving of the 
 tongue to the roof of the mouth, and other un- 
 pleasant effects of lack of saliva. These last 
 forms of activity must be due to impulses coming 
 to the glands or to the secretion center in the 
 brain stem from the cortical regions of the brain, 
 and they are called psychic reflexes or conditioned 
 reflexes. That is, the reflexes are conditioned 
 upon the experience of the individual somewhat 
 as follows : If the visual experience of a lemon is 
 followed a number of times by the taste of the 
 • lemon and the reflex excitation of the salivary 
 glands from the presence of the acid in the mouth, 
 
THE SENSE ORGAN OF TASTE 65 
 
 it may come about that the sight of the lemon 
 unaccompanied by its entrance into the mouth 
 will cause the flow of saliva. The stimulus to 
 the reflex activity has changed from one of con- 
 tact of a substance with the mucous membrane of 
 the mouth to a visual stimulus. As a result of 
 the development of these psychic or conditioned 
 reflexes, if one sees a certain kind of substance 
 that he is going to taste, the flow of saliva neces- 
 sary to reduce it to a tastable form is brought 
 about even before the substance has entered the 
 mouth. Pavlow cites a case in which a handful 
 of clean stones placed in the mouth of a dog pro- 
 duces a very slight flow of saliva, while the same 
 material in the form of fine sand causes a copious 
 flow of saliva. Such cases as this indicate the 
 great delicacy with which the salivary secretion 
 is adapted to the condition of the substances en- 
 tering the mouth. No sapid particles entering the 
 mouth dry can stimulate the taste mechanism 
 except through the mediation of the saliva. 
 
 The Tongue: Its Muscles and Covering 
 Membranes 
 
 Considered as a part of the taste mechanism, 
 the tongue is a body of irregular shape, occupy- 
 ing a large portion of the mouth cavity. It is 
 composed largely of muscles, covered with a 
 mucous membrane very similar to that which 
 
e(> THE SENSE OY TASTE 
 
 lines the whole mouth cavity. It has an upper, 
 or superior surface, a lower, or inferior surface, 
 two sides, and a tip, in addition to the base, or 
 region of its fixation. The muscles are of in- 
 terest in that they give to the tongue its great 
 variety of movements, and the membrane-covered 
 surfaces are of especial interest, because in them 
 are found by far the greatest number of the nerve 
 endings or the sensory ends of taste. 
 
 The tongue is made up of seventeen muscles, 
 acting in three planes — vertical, longitudinal, and 
 transverse. Separating these muscles one from 
 another are layers of fatty tissue, enabling the 
 muscles to glide easily over each other. Fifteen 
 of these muscles are extrinsic in the sense that 
 one end of each has Its point of attachment out- 
 side of the tongue. It is these muscles especially 
 that give the tongue its great motility. By the 
 contraction of single muscles or contraction in 
 various combinations the tongue is protruded or 
 drawn back, the tip raised or lowered, the dorsal 
 surface pressed against the roof of the mouth or 
 withdrawn toward the floor of the mouth, the 
 tongue protruded and turned to one side or the 
 other. In addition to these extrinsic muscles there 
 is a pair of intrinsic muscles, each having both 
 points of attachment within the tongue. By their 
 contraction the sides of the tongue are raised and 
 drawn together, 
 
THE SENSE ORGAN OF TASTE 67 
 
 These muscles are richly supplied with blood 
 vessels and receive an especially large supply of 
 nerve fibers from the hypoglossal, which is known 
 as the motor nerve of the tongue, and some from 
 the lingual branch of the seventh, or facial, nerve. 
 
 It is generally believed that the tongue move- 
 ments serve the sense of taste only as they facili- 
 tate contact of the sapid substances with the real 
 taste endings; for instance, by pressure of the 
 tongue against the roof of the mouth, and by its 
 protrusion from the mouth to receive the stimuli 
 upon its surface. However, It has been asserted 
 by some investigators that the movements are of 
 more direct use in the taste process, in that tongue 
 movements in themselves tend to increase the sen- 
 sitivity of the taste mechanism. But careful ex- 
 periments in which the tongue was rendered 
 motionless during tasting show that taste sensi- 
 tivity is just as great as when the tongue is free 
 to move. 
 
 By far the most important portion of the 
 tongue is its mucous covering. This varies con- 
 siderably in character in different regions, being 
 thickest and toughest on the superior surface 
 where it comes into contact with objects taken into 
 the mouth, and thinnest on the inferior surface 
 where it is ordinarily protected from such con- 
 tact. On the sides and tip it is moderately thick 
 and tough. The tongue covering has a highly 
 
68 THE SENSE OF TASTE 
 
 complex structure. Two distinct layers, or strata, 
 are commonly described: the more superficial, or 
 epithelial layer, and the deeper layer, called the 
 chorion. The first, or epithelial, layer contains 
 all of the sensory endings concerned in taste upon 
 the tongue, and these will be described later. The 
 second is more complex and consists of connective 
 tissue, a great network of blood vessels, nerve 
 fibers, and numerous glands and their ducts which 
 open upon the surface of the tongue. Upon the 
 more superficial surface of this inner layer there 
 is an extremely large number of slight elevations. 
 These are apparent to the unaided eye upon the 
 tongue surface, since the epithelial layer of the 
 membrane follows very closely the contour of this 
 deeper layer. These elevations are called papillae. 
 (Fig. 2.) They vary in size and shape and are 
 quite unevenly distributed upon the surface of the 
 tongue. On the inferior surface there are none, 
 while on the superior surface they are most numer- 
 ous. With the aid of the papillae on this sur- 
 face the tongue can be divided into two parts, an 
 anterior or horizontal portion and a posterior or 
 vertical portion. The former includes about the 
 forward two-thirds of the tongue and the latter 
 the posterior third. These two parts are separated 
 by a row of relatively large elevations, about ten 
 or twelve in number, and arranged in the shape of 
 a V, with the open poi-tion of the V turned for- 
 
THE SENSE ORGAN OF TASTE 69 
 
 TONSIL. 
 
 Fig. 2. 
 
70 THE SENSE OF TASTE 
 
 ward. From the apex of the V a furrow passes 
 forward to the tip of the tongue, dividing the an- 
 terior portion laterally into two halves. The 
 posterior portion is broken up into a series of 
 folds taking about the same direction as the legs 
 of the V. 
 
 Classification of Papilla 
 
 The papillae of the tongue have been described 
 and classified more or less in detail since the 
 middle of the seventeenth century. They can be 
 grouped into four classes (Fig. 2), the circum- 
 vallate, the fungiform, the filiform, and the 
 foliate papillas, each group having certain dis- 
 tinctive characters. A fifth group is sometimes 
 added and comprises the hemispherical, or simple, 
 papillas. 
 
 The circumvallate group comprise the largest 
 and the most important papillae. There are only 
 from eight to twelve or sixteen of this type, and 
 by their arrangement they form the V-shaped 
 figure on the superior surface of the tongue, men- 
 tioned above, and which divides the anterior two- 
 thirds from the posterior third of the tongue. 
 These papillae are found nowhere else. They rise 
 only slightly above the surface of the tongue from 
 the bottom of a pit or cup-shaped depression, 
 giving the impression of a small mound sur- 
 rounded by a ditch, whence the name, circum- 
 
THE SENSE ORGAN OF TASTE 71 
 
 vallate. In a few cases more than one papilla 
 rises from a single pit, but in most cases there is 
 but one. The papilla itself has an average height 
 of 2 millimeters, with a diameter at the top of i.o 
 to 1.5 millimeters, and slightly less at the base. 
 The cup-shaped depression averages about i to 
 1.5 millimeters in depth. The largest of these 
 papillae is that one forming the apex of the 
 V-shaped figure and is called the foramen cscum. 
 The smallest are those found at the ends of the V. 
 
 The fungiform papills are so called on account 
 of their resemblance to a toadstool. Each con- 
 sists of a rather slender stalk capped by a rela- 
 tively large, rounded head, about .8 to i.o milli- 
 meter in diameter. The whole papilla has an 
 average height ranging from 1.0 to 1.5 milli- 
 meters. These are scattered very irregularly 
 over the superior surface of the tongue, most of 
 them being found on its anterior two-thirds. 
 However, a few are found back of the circumval- 
 late papilla, but always very close to them. They 
 are most numerous on the sides and the tip of the 
 tongue, where they appear as bright red points 
 upon the paler background of the tongue cover- 
 ing. The total number of this type has been esti- 
 mated at from 150 to 200. 
 
 The third type, the filiform papillas, cover the 
 whole superior surface of the tongue and are so 
 numerous that no estimation of their total num- 
 
72 THE SENSE OF TASTE 
 
 ber has been made. They are arranged in fairly 
 regular lines running to each side from the middle 
 line of the tongue and parallel to the lines formed 
 by the circumvallate papillae. They are believed 
 to contain no sensory ends of taste and have only 
 a mechanical function, if any, in connection with 
 the taste mechanism. They are conical or cylin- 
 drical in form and vary in height from 1.5 to 2,5 
 millimeters. Sometimes these papilla: are covered 
 with tiny secondary papillae, which, however, are 
 not apparent to the unaided eye. 
 
 The foliate papillae consist of numerous small 
 folds of the membranous covering of the tongue 
 upon its sides and just in front of the line formed 
 by the circumvallate papillae. In these folds a 
 large number of the taste bodies are imbedded. 
 In certain animals, especially the rodents, these 
 foliate papillae form a very prominent part of the 
 tongue, while in man they are no more prominent 
 than the other forms. 
 
 The hemispherical, or simple, papillae are 
 found distributed over the whole tongue surface 
 and form in many cases secondary papillae upon 
 the larger fungiform and circumvallate type. 
 
 The papillae of these different types contain the 
 largest number of the sensory ends of taste, or the 
 taste bodies. These structures will be discussed 
 in detail later. They are most numerous in the 
 circumvallate papillae, where one may find hun- 
 
THE SENSE ORGAN OF TASTE 73 
 
 dreds imbedded in the side walls of one papilla. 
 They are also found in the side walls of the de- 
 pression from which the papilla rises. The fungi- 
 form type also contain these taste bodies im- 
 bedded in their side walls, although there are 
 some in which none have been discovered. Ac- 
 cording to Nagel, the taste bodies have never 
 been found in the filiform type. He ventures the 
 opinion that the taste bodies are not necessary to 
 produce taste sensations, with the result that the 
 filiform papillae may, after all, have something to 
 do with taste sensations. There is always the 
 possibility, first suggested about 1870, that the 
 free nerve endings in the tongue surface may give 
 rise to taste sensations. 
 
 The Determination of the Taste Areas 
 
 How shall the limits of the taste mechanism be 
 determined? Two methods have been employed, 
 and usually in conjunction. The first, or the ana- 
 tomical method, consists in searching for the taste 
 bodies (to be described later), and when they are 
 found, to assume the possibility of taste sensations 
 from the stimulation of that region. The second, 
 or the physiological method, consists in applying 
 stimuli of various sorts to different regions and 
 finding whether taste sensations result. The 
 limits of the taste mechanism, when determined 
 by these two methods taken separately, do not 
 
74 THE SENSE OF TASTE 
 
 always agree. But there are cases in which only- 
 one or the other method taken alone can be ap- 
 plied. For instance, in the case of the embryo 
 it is clear that only the anatomical method can 
 be used, and in the case of the living human being 
 only the physiological, or stimulation, method 
 can be used. 
 
 The discrepancy between structure and func- 
 tion is possibly due, in part, to the presence of 
 functionless taste bodies, useless landmarks in 
 regions where in earlier stages of evolution the 
 taste function may have been of vital importance. 
 Such an explanation has been offered for the pres- 
 ence of taste buds upon the upper surface of the 
 soft palate and upon the walls of the larynx and 
 the vocal cords. But there are at least two other 
 causes for the differences in limits of the taste 
 sense as determined by the different experi- 
 menters, — careless and imperfect technic of ex- 
 perimentation and the great individual differ- 
 ences, according to age, race, and other condi- 
 tions. Just on account of these individual 
 differences it is impossible to define the limits of 
 the taste sense which shall hold for all persons; 
 one can only give averages and avoid the excep- 
 tions. Taking the average adult as tested by the 
 two methods, one can say that the taste mechan- 
 ism includes the following: 
 
 I. The superior, or upper, surface of the 
 
THE SENSE ORGAN OF TASTE 75 
 
 tongue, with the exception of a patch just back 
 of the tip. The size of this patch, which is insen- 
 sitive to all taste stimuli, varies considerably with 
 the kind of stimulus used and its intensity. 
 
 2. The sides and tip of the tongue. The 
 under surface of the tongue of human beings is 
 said to be insensitive to taste. 
 
 3. The soft palate, the uvula, and the tonsils, 
 although the extent of these parts that is sensitive 
 Is subject to considerable variation. Kiesow and 
 others fail to find the uvula sensitive at all. 
 
 4. The gums, the hard palate, and the mucous 
 membrane of the lips are generally considered to 
 be insensitive to taste. This absence of taste sen- 
 sitiveness upon the hard palate, or roof of the 
 mouth, is interesting when one considers its close 
 connection with taste in popular speech. To 
 " tickle the palate " with delicious food, to make 
 food "palatable," are very common, though mis- 
 leading, expressions. However, two very care- 
 ful investigators have reported that the lining of 
 the whole mouth cavity, including gums, the lining 
 of the cheeks, the hard palate, and even the teeth, 
 are sensitive to sour stimuli. Acetic acid of full 
 strength was used as a stimulus In these experi- 
 ments. 
 
 5. The epiglottis, parts of the larynx, and the 
 vocal cords are sensitive to taste stimuli. Not 
 
^e THE SENSE OF TASTE 
 
 only have the taste bodies been discovered in 
 these parts, but certain investigators, by applying 
 solutions of bitter, sweet, etc., have been able to 
 elicit the corresponding sensations from these 
 parts. To these taste organs have been at- 
 tributed the tastes aroused by certain vapors, such 
 as chloroform, ether, etc. 
 
 6. The regio olfactoria, or the olfactory 
 membrane, has been said to give rise to taste sen- 
 sations, and the question has aroused much dis- 
 pute. The evidence for thus attributing taste to 
 the smell mechanism consists in the discovery in 
 the regio olfactoria of bodies similar to taste 
 bodies, and the further fact that breathing chloro- 
 form through the nose gives rise to a stinging 
 sensation, followed by a sweet taste. Introspec- 
 tion seems to localize this tasfe in the nostrils. 
 Nagel, however, denied the existence of this so- 
 called " nasal taste " and performed a simple 
 experiment to prove his contention. He finds that 
 if one allows chloroform or ether vapor to be 
 blown into his nostrils he will get a burning sen- 
 sation, followed in the first case by a sweet taste 
 and in the second by a bitter taste. But if while 
 the vapor is entering the nostrils the person con- 
 stantly utters a vowel sound, thus closing the pas- 
 sage between the nasal and mouth cavity, the 
 sweet and bitter tastes will disappear, while the 
 burning sensation remains. Nagel holds that this 
 
THE SENSE ORGAN OF TASTE 77 
 
 shows that the taste sensations must be due to the 
 stimulation of parts other than the nasal cavity. 
 The same conclusion has been reached by the 
 more careful researches of Nagel's students and 
 others upon individuals whose nasal cavity and 
 mouth cavity have been effectually separated 
 either by growths or by artificial means. 
 
 One conclusion seems generally supported by 
 the investigations of the distribution of taste, 
 namely, that one cannot assert positively that 
 wherever tastes have been definitely aroused there 
 taste organs will be discoverable, or the converse 
 of this, that wherever taste buds are found there 
 taste sensations can always be aroused. 
 
CHAPTER VI 
 
 Sensory Elements of the Taste Mechanism 
 
 Taste Buds and Their General Characteristics 
 
 Each sense mechanism has an arrangement 
 more or less mechanical for modifying the stimu- . 
 lus, and another mechanism which transforms the 
 stimulus into the nerve impulse, that message 
 which is carried from sense organ to brain and 
 there gives rise to consciousness. We know very 
 little about the real nature of this nerve impulse 
 transmitted from sense organ to brain, aside from 
 its speed and a number of conditions affecting it. 
 Some call it a chemical phenomenon, others an 
 electrica). phenomenon, and still others an electro- 
 chemical or physicochemical one. We know even 
 less — in fact, nothing — about the change from 
 nerve impulse to consciousness. But there are 
 certain facts fairly well determined by micro- 
 scopical examination of the sense organ about the 
 nature of the mechanism which transforms the 
 physical stimulus into a physiological one. In the 
 preceding chapter the more mechanical features 
 
 78 
 
TASTE MECHANISM 79 
 
 of the taste mechanism have been reviewed, and 
 in this one we will describe the transforming 
 mechanism. 
 
 A bout 1 865 it wasjfoundjhat the coverings_Qf 
 the tongue^~of^ammals_and later THe^_nningof 
 the mouth cavity contajned^ perattar35me_bod^ 
 which, on account of their apparent shageand 
 their connection with the sense of taste, j^^ere 
 qalleff taste~beakersr" Small lissures called taste 
 ^oi:^,;w:ere discovered aniong the most superSoal 
 epithelial__cells of the. mucous membrane of the 
 tongue, and thfise were thought to lead into tJiP 
 small, flask-like chambers. Further study showed 
 tKat the Ijeakers were not in reality hollow, but 
 qnnsjsted of cl osely packe d gr oups of mo dified 
 egithelial_cells. They were then given thejiamg 
 of taste buds, on account oftheir resemblance to 
 a Du3~wItH~iFs tightly folded petals. These have 
 been spoken of frequently in the preceding pages 
 as sensory eQd§j and the regions in which they 
 are round were enumerated. 
 
 Each taste bud is set rather deeply in the 
 epithelial layer of the mucous membrane cover- 
 ing the sides of the papillee and communicates 
 with the surface only by the above-mentioned 
 taste pore. Thus the tasteJmdjs_Erote£ted^ ft^om 
 direct stimulatioa- by all substances exce£t tHose 
 wfeciTcan gain access througjL the narrow jopeiir 
 in§r^Occasionally taste buds are found whigh 
 
8o THE SENSE OF TASTE 
 
 lack this gustatory pore and communicate directly 
 with the tongue surface. Such cases, however, are 
 to be considered as exceptions. Likewise, twin 
 taste buds are sometimes found, having a common 
 base, but with peripheral ends distinct. These, too, 
 are merely exceptions to the ordinary form and do 
 not represent a type. The taste buds are globular^ 
 \q^ shapcj^ measuring about Tolto 80 tHmisandffis 
 of a millimeter in TengtTi and about "CO thou- 
 sandths gf a. iiullimelgr^^jdiameter. The taste 
 pore aveMiges_^nly about_^„ jhousandths^gf a 
 millimefer in diameter. 
 
 Supporting Cells, Gustatory Cells, and Nerve 
 Filaments 
 
 A microscopical examination of the taste bud 
 shows it to be composed— q| three structures. 
 First, there is a series of modified epithelial 
 cells closely packed side by side and forming 
 a kind of hollow shell and determining the 
 limits of the taste bud. These are sometimes 
 called marginal, or supporting, cells. They are 
 very long and narrow and their thickest part is 
 that occupied by the relatively large nucleus. The 
 extremities of the cells directed toward the taste 
 pore are quite long and thin and are gathered 
 together so as to form a small circular opening, 
 the neck of the taste beaker or bud. Within this 
 hollow globe thus formed some of the same kind 
 
TASTE MECHANISM 8i 
 
 of cells are found, but it is almost entirely occu- 
 pied by the second type of structure, the taste cell. 
 These ordinarily range in number from lo to i6 
 within any one bud, but sometimes as few as two 
 or three have been found. These cells are longer 
 and even more slender than the supporting cells 
 and are very closely packed. The peripheral por- 
 tion of the cell is very much elongated and ends 
 in a hair-like filament which extends into the taste 
 pore. All of these hair-like endings of the taste 
 cells gather into a kind of brush within the taste 
 pore. The centrally directed ends of these cells 
 may have various forms — that is, there may be 
 one long, thin branch or a number of branches, 
 none of which, however, pass beyond the limits 
 of the taste bud. 
 
 The third kind of structure found in a taste 
 bud is perhaps the most important and consists 
 of the fine branches of nerves which enter the 
 taste bud at its base and twine around the taste 
 cells. They do not actually grow into the cells, 
 but pass through the taste bud and end very near 
 to the taste pore In the form of small knobs or 
 knots. Some of the fibrils, after reaching the 
 peripheral end of the bud, turn back and really 
 end in the more central portions of the bud. 
 
82 THE SENSE OF TASTE 
 
 Relations Among the Structures Within the 
 Taste Bud 
 
 A great deal of experimental work has been 
 done to determine the relations among these three 
 parts of the taste bud. It was at one time thought 
 that the supporting cells were modified epithelial 
 cells and only served as a structural support for 
 the taste cells, which were real nerve cells. Ac- 
 cording to this view, the taste cell is a neurone * 
 which is directly affected by the stimulus and 
 forms the first link in the chain of neurones con- 
 necting the surface of the body with the brain. 
 They were thought to be analogous to the olfac- 
 tory cells, which are true nerve cells. But a num- 
 ber of facts more recently determined tend to 
 minimize the distinction between supporting cells 
 and taste cells. For instance, when certain stains 
 are employed for isolating the different struc- 
 tqres it is found that these two sorts of cells stain 
 alike, while the nerve fibrils within the buds stain 
 differently from them. This is taken as good 
 evidence that there is a difference in the composi- 
 tion of the taste cells and the nerve fibrils, and a 
 likeness between the taste and the supporting 
 cells. In fact, both types of cells are now con- 
 sidered to be modified epithelial cells and to be, 
 
 ♦Neurone is the name given to a nerve cell, and includes 
 the cell body with its nucleus, and all of its branches, 
 
TASTE MECHANISM 83 
 
 in a sense, supporting cells. The former serve as 
 supports for the very delicate nerve fibrils as they 
 pass through the taste bud, and the latter, in ad- 
 dition to acting as supports in this way, also form 
 the walls of the taste bud and thus protect the 
 nerve fibrils from undue compression. Accord- 
 ing to this view, then, the nerve fibrils themselves 
 are directly affected by the stimuli. Their knob- 
 like endings, which are found so closely asso- 
 ciated with the taste pore in most cases, lend 
 support to this view. 
 
 One further sort of evidence tends to show the 
 merely secondary function of these two types of 
 cells in the taste bud. Certain portions of the 
 tongue, e.g., parts of the tip and sides, which are 
 extremely sensitive to taste stimuli, have very few 
 taste buds, or none at all. But there is a multi- 
 tude of free nerve endings in these parts which 
 are thought to function without the aid of the 
 supporting, or taste, cells. It will be recalled that 
 in Chapter V it was necessary to conclude that 
 there seemed to be no absolute dependence of 
 taste sensations upon the presence of taste buds. 
 
 The Sensory Nerves of Taste 
 
 The taste sense differs from most of the other 
 special senses in a number of respects, some of 
 which have been mentioned in the preceding 
 chapter. Still another striking difference is to be 
 
84 THE SENSE OF TASTE 
 
 found in the nerve supply for taste as compared 
 with that of the senses of sight, hearing, and 
 smell. In the latter group there is one nerve 
 which carries the impulses from the sense organ 
 to the brain. Thus, we have the optic nerve for 
 vision, the auditory nerve for hearing, and the 
 olfactory nerve for smell. In taste, however, no 
 single cranial nerve can be called the nerve of 
 taste or the gustatory nerve. There has always 
 been a great deal of difference of opinion as to 
 how the taste fibers are carried to the brain, no 
 small part of which has been due to the seeming 
 necessity for finding " a taste nerve." As early 
 as 1823 evidence began to accumulate to show 
 that more than one nerve must be involved. 
 Other contributing factors to this confusion are, 
 first, the use of experimentation upon animals — ■ 
 the conclusions from which have been considered 
 valid for man as well as animals, an assumption 
 which is not necessarily correct; and, second, the 
 fact that there seem to be rather pronounced in- 
 dividual differences in the course taken by the 
 fibers from taste bud to brain center. Three of 
 the cranial nerves are now generally conceded to 
 carry taste fibers: the lingual, which is a branch 
 of the trigeminus, or fifth, nerve; the glosso- 
 pharyngeal, or the ninth, nerve, and the vagus, 
 or the tenth, nerve. The first two of these are 
 more Important for taste jthan the third. The 
 
TASTE MECHANISM 85 
 
 lingual carries the fibers from the anterior two- 
 thirds of the tongue, the upper surface, and the 
 sides of that portion of the tongue and the tip; 
 the glossopharyngeal carries the fibers from the 
 posterior third of the tongue, including the base 
 of the tongue, the soft palate, and the papillae 
 foliata; the vagus carries fibers from the epi- 
 glottis and the larynx. 
 
 Although the above facts are well established, 
 the more important question is, What is the origin 
 of these fibers and how do they get into the nerve 
 trunks in which they are found? To make this 
 matter clear a word must be said about the gen- 
 eral nature of sensory nerve paths. The connec- 
 tion between a sense organ and the brain consists 
 of a series of separate links, which always remain 
 distinct units. Each cell, or neurone, as one of 
 these units is called, consists of a body, which con- 
 tains the nucleus, and two sets of branches. In 
 one set the branches are very short and numer- 
 ous, called dendrites ; in the other there is usually 
 only one branch, called the axone, which is rela- 
 tively long. A group of cell bodies is called a 
 ganglion. In practically all sensory nerves these 
 ganglia are situated outside of the central nerv- 
 ous system. The ganglia of the spinal nerves are 
 located just outside of the spinal cord and are 
 called simply spinal ganglia. T^he ganglia of the 
 cranial nerves usually receive special names. 
 
86 THE SENSE OF TASTE 
 
 Thus, the ganglion for the great trigeminal, 
 or fifth, nerve is called the gasserian ganglion. 
 Of the two for the glossopharyngeal, or ninth, 
 nerve that one of interest to us is called 
 the petrosal ganglion. The vagus has two 
 ganglia, an upper and a lower; the former, 
 or jugular, ganglion is involved in the sense of 
 taste. 
 
 From these ganglia the branches called the 
 dendrites pass to the sense organ and are found 
 twining around the taste cells in the taste buds. 
 The other branches, the axones, pass into the 
 brain stem and finally end in some brain center. 
 The question, then, is. Do the taste fibers which 
 are found in the lingual branch of the fifth 
 nerve have their cell bodies in the gasserian 
 ganglion, do those found in the ninth nerve have 
 their cell bodies in the petrosal ganglion and 
 those found in the tenth nerve have their cell 
 bodies in the jugular ganglion? These are 
 indeed difficult questions to answer. Reliance 
 must be placed largely upon the results of surgical 
 operations upon these nerves and ganglia, with 
 their resulting effects upon the sense of taste. 
 Earlier reports of surgical operations in which 
 the gasserian ganglion was removed were that 
 the taste sense on the tongue was completely de- 
 stroyed, suggesting that all of the gustatory 
 
TASTE MECHANISM 87 
 
 fibers of the tongue had their origin in the gas- 
 serian ganglion. Later reports, however, were 
 that only the taste sense of the anterior two-thirds 
 of the tongue was destroyed by this operation, 
 suggesting that the fibers found in the glosso- 
 pharyngeal nerve were independent of the gas- 
 serian ganglion and really had their origin in the 
 petrosal ganglion, these fibers getting into the 
 lingual branch of the fifth nerve by a circuitous 
 route. 
 
 The experiments of Gushing indicate, further, 
 that operations with removal of the gasserian 
 ganglion produced a dulling or complete loss of 
 the sense of taste in the anterior two-thirds of the 
 tongue, but this loss was followed later by com- 
 plete recovery. The interpretation of these facts 
 must be that the temporary effect upon the taste 
 sense is only an incidental result of the operation 
 and that the taste fibers for this part of the tongue 
 originate in the geniculate ganglion, which is the 
 ganglion for the facial, or the seventh, cranial 
 nerve, and only get into the lingual branch of the 
 fifth by way of the chorda tympani nerve. 
 Consequently, the chorda tympani, a connecting 
 link between the seventh and the lingual branch 
 of the fifth, is extremely important for the taste 
 sense, since it carries all of the fibers concerned 
 in the taste function of the anterior two-thirds of 
 the tongue. This nerve passes across the cavity 
 
88 THE SENSE OF TASTE 
 
 of the middle ear, and when stimulated mechani- 
 cally, chemically, or electrically at this point is 
 said to arouse taste sensations variously described 
 as sour or metallic, sometimes as sweet and bitter. 
 
 Fig. 3. — Diagram showing some of the various courses which 
 have been advocated for the taste fibers in man. (Courtesy W. 
 B. Saunders Company.) 
 
 Salt tastes alone have never been reported as re- 
 sulting from such stimulation. 
 
 The taste fibers of the vagus seem to have 
 their cells of origin in the jugular ganglion of 
 that nerve. Thus, while taste fibers are found in 
 the fifth, ninth, and tenth cranial nerves, it 
 seems that the fibers really originate in the 
 seventh, ninth, and tenth nerves. The accom- 
 panying figure (Fig. 3), after Gushing, will show 
 
TASTE MECHANISM 89 
 
 the facts about the distribution of the gustatory 
 fibers. 
 
 The Cerebral Taste Centers 
 
 The first unit in the path connecting sense 
 organ of taste and brain, represented by the 
 neurones having their cell bodies in the ganglia 
 described above, all end in the medulla oblon- 
 gata, in the neighborhood of the fourth ven- 
 tricle. These terminals, called the primary sen- 
 sory nuclei for the seventh, ninth, and tenth 
 nerves, are all included in the nucleus of the 
 solitary bundle. 
 
 From these primary sensory nuclei a second 
 series of conducting units begins, sending their 
 fibers In two directions, downward into the spinal 
 cord and upward toward the higher brain centers. 
 Those fibers passing downward make connections 
 in the medulla with the motor centers controlling 
 mastication and swallowing and in the cord with 
 the various motor centers. These connections 
 make possible the reflex responses to taste stimuli, 
 such as secretion of gastric and the other juices 
 of the alimentary canal. Little is known about 
 the course taken by the fibers which must carry 
 the gustatory impulses from the primary sensory 
 nuclei to the higher brain centers. It is quite 
 likely that this second conduction unit is repre- 
 sented by fibers which mingle with those carrying 
 
90 "THE SENSE OF TASTE 
 
 impulses from the sense organs of skin and 
 muscles to the higher centers, and which are found 
 in the median fillet, or the pathway in the brain 
 stem for body sensations. These fibers end in the 
 thalamus.* In the thalamus a third conducting 
 unit begins and carries the impulses to a still 
 higher center in the cortex of the cerebrum. Ex- 
 actly what course the fibers take from the thala- 
 mus, or just where the cortical center for taste 
 is, has not been definitely determined for human 
 beings. 
 
 Indeed, less is known about the localization of 
 the taste function in the cortex than about any 
 of the other special senses. This is not due to 
 lack of interest, for a large number of researches 
 have been reported in this field. The reason is, 
 rather, that there are certain difficulties in the 
 way of its solution. First, the help to be got 
 from physiological experiments upon animals is 
 limited, because of the close relation between the 
 senses of taste and smell, with the consequent un- 
 certainty in interpreting behavior after surgical 
 operations. And, second, since the exploration 
 of the most accessible portions of the cortex has 
 not revealed a taste center, it is probably located 
 
 *The thalamus is a center in the upper part of the brain 
 stem, where connections are made between the cortex or 
 outer layer of the brain proper and lower centers of the 
 nervous system. 
 
TASTE MECHANISM 91 
 
 somewhere upon the ventral, or mesial, surfaces 
 of the cerebrum, where experimental work is 
 practically impossible. Clinical and physiological 
 investigations have furnished conflicting results. 
 A survey of recent work suggests that the most 
 probable center for taste is in the hippocampal 
 gyre near the anterior portion of the temporal 
 lobe. No more definite localization is at present 
 possible. 
 
CHAPTER VII 
 
 Taste-Producing Substances 
 
 Adequate and Inadequate Stimuli 
 
 Ever since the doctrine of the specific energy 
 of sensory nerves was presented by Miiller, and 
 since modified into the specific energy of sense 
 organs or of cerebral centers, two sorts of stimuli 
 for a sense organ have been spoken of. There 
 are those called adequate, — ^for which the sense 
 seems to be especially adapted, — and those called 
 inadequate, to which the sensory mechanism is 
 sensitive by virtue of its possession of a general 
 irritability or sensitivity. It is a matter of com- 
 mon knowledge that one sees because his visual 
 mechanism is stimulated by light, or rather by the 
 vibrations of the luminiferous ether, and that this 
 is the appropriate stimulus for visual sensations. 
 But it is just as well known that if one receives a 
 blow upon the head he will see " stars," or if he 
 presses his finger upon his eyeball he will see 
 patches of light. The sensations produced in this 
 latter fashion are due to the mechanical stimula- 
 tion of the sensitive visual mechanism, which re- 
 sponds with its specific kind of sensation. The 
 
 92 
 
TASTE-PRODUCING SUBSTANCES 93 
 
 questions to be answered in this chapter are, — 
 What is the kind of stimulus to which the taste 
 mechanism is especially adapted? and, Are there 
 other or inadequate stimuli which can produce 
 taste sensations? In answering these questions it 
 is well to keep in mind the biological function of 
 the sense organ of taste. Situated as it is at the 
 entrance of the alimentary canal it has been 
 called the " eye of the stomach," whose duty it is 
 to prevent the entrance into the body, by way of 
 the mouth, of harmful substances. If this is so, 
 the adequate stimulus for taste would be any kind 
 of substance which might be taken for food. 
 
 Adequate Taste Stimuli 
 
 All substances may be classed either as sapid, 
 tastable, or insipid, tasteless. And one of the 
 main conditions for sapidity is solubility. A sub- 
 stance to be tasted must enter the mouth cavity 
 as a fluid or else after being taken into it must 
 be dissolved in the saliva. Thus, the adequate 
 stimulus for the taste organ may be said to be a 
 fluid. Recalling the structure and location of the 
 sensory ends of the taste mechanism, it is at once 
 inferred that only fluids can enter the taste pore 
 and stimulate there the nerve endings of taste. 
 It might then be assumed that all fluids should 
 produce taste sensations. But all soluble sub- 
 stances are not sapid or tastable. Consequently, 
 
94 THE SENSE OF TASTE 
 
 other conditions of sapidity have been sought, 
 among them being chemical constitution. 
 
 One of the most interesting attempts to solve 
 the question of the conditions of sapidity is that 
 which makes the only condition necessary, the 
 contact of the substance with the nerve endings 
 within the taste buds. Now, Graham pointed out 
 that all tastable substances belong to the class of 
 crystalloids, while tasteless substances belong to 
 the colloids. It is known, too, that living mem- 
 branes are permeable by certain solutions and not 
 by others. Colloid membranes, of which all of 
 the mucous membranes of the body are examples, 
 are impervious to colloids in solution, while the 
 passage of crystalloids in solution is rapid. 
 Hence, no colloids, even those in solution, could 
 actually reach the free nerve endings of the taste 
 buds. As Nagel says, however, the truth of this 
 assumption is not easy to settle, since it is very 
 difficult to get pure colloids and to make sure that 
 their chemical constitution is not modified by the 
 saliva before contact with the taste nerves. Other 
 possibilities will be discussed in the chapter deal- 
 ing with the theories of the taste function. It 
 will be sufficient here to say that the adequate 
 stimulus to taste is a liquid, or a solid, or gas, 
 which may be dissolved in the saliva. Gases such 
 as chloroform vapor, carbonic acid gas, and the 
 like, were at one time thought to act directly upon 
 
TASTE-PRODUCING SUBSTANCES 95 
 
 the taste buds, but a safer view is that the gases 
 are first dissolved in the saliva before acting on 
 the taste mechanism. A few experiments have 
 been reported in which the gases were said to 
 have produced taste sensations when the mucous 
 membrane was dry, but it is practically impossible 
 to produce this condition, since the small glands 
 of the tongue open directly into the fissures con- 
 taining the taste buds and tend to keep the neigh- 
 borhood of the taste pores in a moist state. 
 
 To say that the adequate stimulus for taste is 
 a fluid is to give only an incomplete description of 
 adequate stimuli. In the case of vision the ade- 
 quate stimuli are ether vibrations; and the dif- 
 ferent visual sensations, reds, yellows, blues, etc., 
 are attributed to ether vibrations of different 
 rate. 
 
 And in the sense of hearing, the adequate 
 stimulus of which consists of air vibrations, it is 
 the different vibration rates that account for the 
 qualitative or pitch differences in sound sensa- 
 tions. What characteristics of the stimulating 
 fluids are responsible for the specific sensations 
 sweet, sour, bitter, and salt? The answer to this 
 question has been sought in the chemical constitu- 
 tion of the sapid substances. There is found to 
 be a certain relation between chemical groups and 
 the taste sensations they produce. Kiesow and 
 others have pointed out that acids are sour; that 
 
96 THE SENSE OF TASTE 
 
 many chemical salts have a salt taste; that many 
 carbohydrates taste sweet, and that most of the 
 alkaloids are bitter. There are too many excep- 
 tions to these simple relations between chemical 
 structure and sensation quality to have them serve 
 as an answer to our question. There are chemical 
 salts which taste sweet, there are acids which do 
 not taste sour, and there are chemical substances 
 whose tastes differ according to their concentra- 
 tion and even according to the part of the tongue 
 which they affect. 
 
 Sternberg, who has made a very extensive 
 study of the relation between chemical structure 
 and sensation quality, has recognized the impos- 
 sibility of finding a simple relation between chemi- 
 cal groups and sensation quality. His method of 
 study consisted in cataloguing separately all those 
 substances which taste sweet, sour, bitter, and 
 salt, and then looking for similarities of structure 
 within the same sensation group and differences 
 among different groups. This is just the opposite 
 of the customary procedure which was to take the 
 chemical groups as a starting point and examine 
 into the tastes aroused by them. He finds no 
 difference in the molecule of a substance produc- 
 ing a sweet taste and a molecule of another 
 substance producing a bitter taste, and finds simi- 
 larities among the molecules of substances pro- 
 ducing different tastes. He is forced to the con- 
 
TASTE-PRODUCING SUBSTANCES 97 
 
 elusion that the tastes are due to the character of 
 the intramolecular vibrations; that the taste 
 mechanism is capable of responding to the rela- 
 tions among the atoms which have escaped the 
 other senses, even when their keenness is increased 
 by all sorts of artificial devices. Nagel, in review- 
 ing this work of Sternberg, says that, in spite of 
 the interesting facts which have been accumulated 
 by him and others, very little has been contributed 
 to the solution of the question of the stimulus for 
 the different taste qualities. 
 
 Before dismissing the question of adequate 
 stimuli one other set of phenomena ought to be 
 mentioned. There are cases in which sapid sub- 
 stances dissolved in the blood produce taste sensa- 
 tions. In cases of diabetes, where sugar is pres- 
 ent in the blood, a sweet taste is experienced in 
 the absence of stimuli upon the tongue surface. 
 Also, in cases of jaundice, where there is an excess 
 of bile, a bitter sensation may be experienced. 
 Here the stimuli affect either the taste nerves or 
 the taste buds directly. There is no reason to 
 think that the stimulation process differs in any 
 other respect from the normal, except in the mode 
 of access to the taste buds. 
 
 Inadequate Taste Stimuli 
 
 Our second question concerns the possibility of 
 other stimuli to taste, or of inadequate stimuli. 
 
98 THE SENSE OF TASTE 
 
 Among these forms of. stimulation three will be 
 considered, namely, mechanical, thermal, and 
 electrical. Are taste sensations produced by 
 mechanical stimulation of the sense organ? Some 
 of the older experimenters reported that tapping 
 the tongue lightly or putting it under slight pres- 
 sure aroused taste sensations of sour and bitter. 
 But there does not seem to be good ground for 
 such a conclusion. No doubt under poorly con- 
 trolled conditions such mechanical stimuli might 
 serve to force sapid substances already upon the 
 tongue into the taste pores and thus stimulate the 
 taste nerves. This, however, would be only an in- 
 direct effect of mechanical stimulation and not at 
 all analogous to the visual sensations produced by 
 mechanical stimulation of the eyeball. 
 
 It is rather interesting to note in this connection 
 that mechanical stimulation of the chorda tym- 
 pani nerve, which carries the impulses from the 
 anterior two-thirds of the tongue, is said to pro- 
 duce taste sensations. In cases in which the ear- 
 drum has been removed, stimulation of the nerve 
 in the middle ear is said by some authorities to 
 produce sweet and bitter sensations, and by others 
 nothing but pricking sensations. 
 
 Thermal stimuli when applied to the tongue 
 do not cause taste sensations, but only sensations 
 of warmth and cold. Thermal stimuli, however, 
 ^re recognized to li^'Ve considerable influence upon 
 
TASTE-PRODUCING SUBSTANCES 99 
 
 the effect of taste stimuli. Two cases are to be 
 noted, that in which the sapid substance itself is 
 either warm or cold and that in which the mouth 
 has been subjected to warm or cold stimuli before 
 the sapid substance is introduced into the mouth. 
 The first condition has received the more attention 
 on account of the importance of temperature in the 
 supposed chemical reaction in the taste buds and 
 the consequent possibility of interpreting the facts 
 in favor of a chemical theory of taste. Both 
 problems have been investigated by Kiesow and 
 others, and the conclusions are' conflicting. Some 
 find that there is a certain optimum temperature 
 for sapid bodies at which the taste sensations are 
 best obtained, although there is no perfect agree- 
 ment as to what this optimum temperature is. It 
 varies from 55 to 120 degrees F. for different 
 authors. At the optimum temperature the least 
 quantity of the sapid substance is necessary to 
 arouse a taste sensation, while a deviation from 
 this temperature in either direction requires a 
 stronger stimulus to arouse the same sort of a 
 sensation. Kiesow, on the other hand, believes 
 that the temperature of the sapid substance makes 
 no difference, but only the temperature of the 
 mouth previous to receiving the sapid substance. 
 For instance, he holds that the sensitivity is just 
 as acute when the temperature of the sapid sub- 
 stance is 32 degrees F. as when it is lOO degrees 
 
100 THE SENSE OF TASTE 
 
 F. But if the tongue is placed in water at 32 
 degrees F. for a few minutes it then becomes in- 
 sensitive to sapid substances, — a kind of anes- 
 thesia results. He believes that the conflicting 
 results obtained by the other investigators are 
 merely the results of distraction of the attention. 
 Whenever the temperature rises or falls beyond a 
 certain point, then this temperature sensation be- 
 comes more impressive than the weaker taste 
 sensation, and the taste sensation drops out of 
 consciousness. It is a well-established fact, at any 
 rate, that thermal stimuli cannot directly arouse 
 taste sensations. 
 
 Taste sensations aroused by passing an electric 
 current through the tongue were reported as early 
 as the middle of the eighteenth century by Sulzer. 
 Since that time a great number of experi- 
 mental researches have accumulated in the at- 
 tempt to answer the question whether an electric 
 stimulus can directly arouse taste sensations, as it 
 will produce sensations of light when it stimulates 
 the eye. In all of this work there has been rather 
 general agreement as to the character of the taste 
 sensations present during electrical stimulation. 
 Thus, when the anode (positive pole) comes into 
 contact with the tongue the taste is said to be sour, 
 while at the point where the cathode (negative 
 pole) touches the tongue a bitter taste is reported. 
 There is less general agreement upon the char- 
 
TASTE-PRODUCING SUBSTANCES loi 
 
 acter of this cathode taste, however, than upon 
 that of the anode taste, some describing it as 
 burning, some as bitter, sweet, or alkaline. 
 
 The great differences of opinion do not con- 
 cern the character of the taste aroused by the 
 electric current so much as the real source of the 
 stimulation of the taste buds. It was suggested 
 by Humboldt about 1 800 that the taste sensations 
 were not caused directly by the electrical stimula- 
 tion of the taste buds, but rather by certain sapid 
 substances which were set free within the mouth 
 by the action of the current on the saliva. It is 
 known that fluid salts can be broken down by elec- 
 trolysis in such a way that at the anode an acid 
 reaction, and at the cathode an alkaline reaction, 
 can be detected. These facts have lent support 
 to the assumption that the saliva thus acted upon 
 by the electric current produces tastable sub- 
 stances. An interesting experiment attributed to 
 Volta about 1800 seemed for a time to refute the 
 whole electrolysis theory. He used an alkaline 
 fluid for the anode, into which the tip of the 
 tongue was dipped. Even in this case the char- 
 acteristic sour taste was still experienced. But 
 this experiment, like all of the others which seem 
 to refute the electrolysis theory of electric stimu- 
 lation, neglects the fact that the electrolysis may 
 occur within the taste bud itself, and hence could 
 not be detected by any test of the tongue surface. 
 
I02 THE SENSE OF TASTE 
 
 nor could the taste sensations thus produced be 
 prevented by immersing the tongue in any kind 
 of a solution, since this need not displace the 
 fluids within the taste bud. The experience of both 
 bitter and sweet tastes at the cathode, if these 
 experiences are genuine, offers some difficulty for 
 the electrolysis theory. The most that can be 
 said is that it is quite likely that electrolysis takes 
 place within the taste bud, but that, in addition 
 to this, there may possibly be a certain direct 
 action of the electrical stimulus upon the taste 
 buds or their nerve endings. 
 
 From this review of the different ways in which 
 the taste organ may be affected it appears that 
 the evidence is not conclusive that mechanical, 
 thermal, or electrical stimuli may arouse taste 
 sensations. Chemical stimulation, which is usually 
 included among the inadequate stimuli for the 
 other senses, is the adequate stimulus for the taste 
 mechanism. 
 
CHAPTER VIII 
 Function of the Taste Mechanism 
 
 Function of Tongue and Salivary Glands 
 
 When sapid substances are taken into the 
 mouth as solids, liquids, or gases they either be- 
 come dissolved in the saliva or mixed with it. 
 The glandular activity, with the resulting secre- 
 tion of the saliva, as described in chapter V, may 
 begin at the sight of the objects or may not begin 
 until the substances have come into contact with 
 the linings of the mouth cavity or tongue. The 
 breaking down of the solid substances and their 
 mixture with saliva is facilitated by chewing 
 movements and by the movements of the tongue. 
 When the substances have been transformed into 
 the liquid state they move toward the back part 
 of the mouth, from which the swallowing reflex 
 movements will carry them into the gullet and 
 stomach. In the course of this movement the 
 fluids will come into contact with the tip, the 
 superior surface, and sides of the tongue, and 
 with portions of the mucous linings of the mouth. 
 
 103 
 
I04 THE SENSE OF TASTE 
 
 And it is just in these regions that we find that 
 the taste organs are located. 
 
 The uneven surface of the tongue, due to the 
 presence of the papillae, tends to retard the move- 
 ment of the fluid substances and to ^ve them time 
 to affect the taste organs. It will be recalled that 
 on the tip and the superior surface of the front 
 part of the tongue there are few taste buds found, 
 even where the papillse of the filiform and fun^- 
 form type are numerous, but a tremendous num- 
 ber of free nerve endings are found close to the 
 surface of the epithelial covering of the tongue. 
 They can be affected by the fluids without passing 
 through a gustatory pore into the taste bud. 
 Now, it happens that the latent time of the sweet 
 sense is very short compared with that for bitter. 
 And since it is known that the bitter sensations 
 are aroused especially by stimulating the circum- 
 vallate papillae, which contain real taste buds, it 
 seems quite probable that the free nerve endings 
 in the forward part of the tongue are real sen- 
 sory ends of taste and are directly affected by the 
 fluid stimuli. It was at one time supposed that 
 sweet tastes could not be aroused on this part of 
 the tongue without the aid of tongue movements. 
 Although this is no longer believed, it is, never- 
 theless, likely that tongue movements which 
 would press its surfaces against neighboring parts 
 of the mouth cavity would bring the sapid sub- 
 
FUNCTION OF TASTE MECHANISM 105 
 
 stances into contact with the free nerve endings, 
 and that more quickly than in the absence of any 
 movement. 
 
 As the fluids pass over the sides and superior 
 surface of the tongue still farther back they meet 
 the foliate and the circumvallate papillae. The 
 character of these papillae is well adapted to re- 
 tard the fluids in their passage and give ample 
 time for stimulating the taste nerves. The for- 
 mer does this by holding the fluid in its long folds, 
 or ditches, and the latter by collecting it in the 
 circular ditches surrounding the papillae proper. 
 In these two types of papillae real taste buds are 
 found, with their taste pores leading from the 
 surface into the interior of the taste bud. It is 
 necessary, then, that the fluid be retained long 
 enough to reach these hidden parts. As might 
 be expected, there is a rather long latent time for 
 the sensations aroused in these parts, namdy, 
 sour and bitter. 
 
 Tongue movements would be of service here, 
 perhaps even more than in the forward portion 
 of the tongue, in forcing the fluids more rapidly 
 through the taste pore. But the tongue move- 
 ments are said to be of use in still another way. 
 The bases of the papillae beneath the epithelial 
 layer are supplied with a rich network of small 
 veins. Now, tongue movements increase the flow 
 of blood to the tongue and these veins become 
 
loe THE SENSE OF TASTE 
 
 congested with blood. Thus, the veins form a 
 kind of erectile mechanism through which the 
 papillae become swollen, and at the same time the 
 crevices in the epithelial tissue are opened wider, 
 and easier access to the taste buds results. This 
 hypothesis of the erectility of the papilla is not 
 generally accepted. 
 
 The devices in connection with the circumval- 
 late and foliate papillae, the circular and linear 
 ditches, for retarding the fluid, may account for 
 certain other characteristics of taste sensations, 
 namely, the difference in duration of the taste 
 sensations. Since the depressions and the taste 
 pores become filled with the sapid substances, the 
 taste sensations ought to last as long as the fluid 
 remains, or until the taste organs become adapted 
 to them, and thus interfere with the production of 
 new and different sensations. But a corrective 
 device for this defect has been assumed by cer- 
 tain investigators in the form of the numerous 
 secretory glands found in the mucous membrane 
 of this part of the tongue. These glands are said 
 to pour their secretions through ducts into these 
 depressions and flush them out, thus removing 
 stimulating fluids and making way for new ones. 
 This mechanism would prevent the confusion 
 which would necessarily occur from the mixture 
 of old and new sapid solutions in the depressions 
 of these papillae. 
 
FUNCTION OF TASTE MECHANISM 107 
 
 The Function of the Taste Buds 
 
 Real difficulties and differences of interpreta- 
 tion come when explanation of what takes place 
 in the taste bud is attempted. Such questions as 
 the following arise, none of which has received 
 a perfectly definite answer. Theories of various 
 sorts are all that can be offered in this connection : 
 
 1. Does the sapid substance affect the taste-bud 
 cells, or only the nerve fibrils that twine around 
 these cells? 
 
 2. If it affects these cells, does it affect the gus- 
 tatory cells only, or both these and the support- 
 ing cells? 
 
 3. Does the sapid substance really enter the 
 taste bud at all, or only affect the ends of the cells 
 which form the so-called entrance to the bud? 
 
 4. Regardless of what portion of the taste bud 
 Is affected by the stimulus, what is the character 
 of the effect produced? Is it mere contact or 
 mechanical stimulation, or is it a chemical process 
 which is set up? 
 
 5. Must different t5^es of receiving structures, 
 of whatever form they may be, be assumed for 
 each type of elementary taste sensation? 
 
 The structural relations among the parts of the 
 taste bud were discussed in the chapter on Sensory 
 Elements. There it was concluded that the 
 analogy between the sense of taste and that of 
 
io» THE SENSE OF TASTE 
 
 certain of the other senses, especially sight and 
 smell, is not so close as it has seemed to be. It 
 will be recalled that in these sensory mechanisms 
 there are modified nerve structures, rods and 
 cones in the eye, and the olfactory cells in the 
 nose, which are affected directly by the stimuli, 
 and in which a transformation of the stimulus 
 takes place, with the resultant nerve impulse. 
 This transformation accompanies a chemical 
 change within these structures, hence vision and 
 smell are called chemical senses. In the taste 
 mechanism, also considered a chemical sense, it 
 was natural to see in the gustatory cells of the 
 taste bud structures with functions similar to that 
 of the rods, cones, and olfactory cells. But the 
 analogy between these types of structures breaks 
 down because the gustatory cells do not have the 
 characteristics of nerve tissue, as revealed espe- 
 cially by the use of differential stains. In fact, 
 as has been said above, there seems to be no 
 fundamental difference between supporting and 
 taste cells. Two further facts seem to indicate 
 that the supporting and gustatory cells take no 
 primary part in the taste function. First, there is 
 no more intimate connection between these cells 
 and the nerve fibrils than that of contact, and the 
 contact seems only incidental to the supporting 
 function. The endings of the nerve fibrils are 
 free from the cells. And, second, those free 
 
FUNCTION OF TASTE MECHANISM 109 
 
 nerve endings in the anterior portion of the 
 tongue seem to arouse taste sensations without 
 the intervention of any structures resembling the 
 taste buds or their cells. Thus, the evidence to 
 date leads to the conclusion that the nerve fibrils 
 alone are the parts affected by the taste stimulus. 
 
 If this hypothesis be correct, is it necessary 
 that the sapid substances should actually enter 
 the taste bud, or only affect its peripheral end? 
 Many of the nerve fibrils entering the taste bud 
 pass through its whole length and end quite near 
 the mouth of the gustatory pore. These might 
 be stimulated without the entrance of the stimulus 
 within the taste bud. But there are many of these 
 fibrils which do not reach to the peripheral end 
 of the bud, but stop far short of this point, and 
 then there are others that reach the entrance of 
 the taste pore but turn back and end in the char- 
 acteristic knob-like formation within the taste 
 bud. In order that these fibrils may be stimulated 
 upon their ends the stimuli would have to enter 
 the taste bud. 
 
 The answer to the fourth question is indeed the 
 most difficult of all. What is the nature of this 
 stimulation by which a fluid substance shall start 
 an impulse along the nerve paths to the brain, 
 which shall there produce sensation? About this 
 last stage of the process nothing is known either 
 about taste or any of the other senses. But very 
 
no THE SENSE OF TASTE 
 
 well-developed theories exist to account for the 
 transformation of the physical stimulus into 
 physiological nerve impulse. For instance, in the 
 case of vision, the stimulus for which consists of 
 ether vibrations, these ether waves cause chemical- 
 changes in certain hypothetical substances within 
 the rods and cones of the retina. It is this chemi- 
 cal change which creates the nerve impulse. In 
 the case of hearing, for which the stimulus con- 
 sists of air vibrations, these waves, being slightly 
 modified by the more superficial portions of the 
 auditory mechanism, finally cause vibrations of 
 the basilar membrane, which, in turn, produces 
 the impulse in the auditory nerve. 
 
 One of the earliest and simplest conceptions of 
 the nature of the process in the taste organ was 
 a mechanical theory proposed by Boyle, about 
 1675. He thought that the particles of various 
 sapid substances differed in size and shape and 
 that on account of these differences they produced 
 different effects in their simple contact with the 
 sensory ends of taste. 
 
 According to Graham, who announced his 
 theory in 1889, sapidity of substances depends on 
 their chemical constitution, colloids being gener- 
 ally insipid and crystalloids being sapid, hence 
 this has been known as a chemical theory. This 
 difference of chemical structure, discussed on page 
 94, was made to account for the contact, or the 
 
FUNCTION OF TASTE MECHANISM 
 
 III 
 
 lack of it, between the substances and the sensory 
 ends, but does not account for the effect produced 
 upon the sensory ends by the substances reaching 
 them. 
 
 Sir William Ramsay prepared an explanation 
 quite analogous to the theories of color vision and 
 called it a dynamic theory. According to him, the 
 real stimulus to the taste organs is molecular 
 vibration, the different taste sensations being due 
 to stimulation by different rates of molecular 
 movement. Just as in the case of the luminiferous 
 ether or of the air there is quite a range of 
 molecular vibration rates, from exceedingly slow 
 to exceedingly rapid. And, just as in the case of 
 vision and hearing, so is the taste mechanism 
 tuned to respond to only the middle range of these 
 molecular vibration rates. Substances may then 
 be insipid, either because their molecular move- 
 ments are too slow or too fast to affect the receiv- 
 ing mechanism. In vision we have the analogous 
 case of the infra-red and the ultra-violet rays not 
 producing visual sensations, because they are be- 
 yond the range of sensitivity of the eye. Yet the 
 effect of these rays can be recorded by other 
 means. The rate of molecular movement depends 
 on the weight of the molecule, so that very heavy 
 or very light molecules would not produce taste 
 sensations. 
 
 About the same time Richet and Gley per- 
 
112 THE SENSE OF TASTE 
 
 formed a series of experiments which seemed to 
 show that the molecular weight of the substance 
 was an important factor in producing taste sensa- 
 tions. They found that the intensity of the effect 
 produced by different salts was in proportion to 
 their molecular weight; that if account was taken 
 of the different molecular weights of the salts 
 used as stimuli the threshold stimulus would be 
 the same for all of the salts. But if solutions 
 were prepared according to the absolute weight 
 of the salts these threshold stimuli appeared to 
 be quite different for the different salts. Later 
 experiments have shown that the same relation 
 does not hold for sour-producing substances, cer- 
 tain sours of very small molecular weight having 
 the sourest taste. 
 
 Sternberg, whose work was mentioned in chap- 
 ter Vtl, recognized only two elementary taste sen- 
 sations, sweet and bitter, and he found no differ- 
 ences in the molecule of substances producing 
 these two sensations. He concludes that it is the 
 intramolecular vibrations that form the real taste 
 stimuli. By transferring the seat of the activity 
 from molecular vibration to intramolecular 
 vibration the whole matter becomes more difficult 
 of solution and verification. Still, the modifica- 
 tion of the theory of Ramsay, made necessary by 
 the work of Sternberg, would leave its essen- 
 tials, namely, that vibrations of some sort form 
 
FUNCTION OF TASTE MECHANISM 1 13 
 
 the stimulus and that the sense organ of taste is 
 tuned to receive only a limited range of vibration 
 rates. 
 
 Granting that a dynamic theory as outlined 
 above, with possible modifications to meet new 
 discoveries, is correct, still another question re- 
 quires an answer. In the visual organ affected by 
 ether vibrations of different rates every theory 
 assumes certain parts of the mechanism sensitized 
 especially to certain vibration rates. To take the 
 theory of Hering, for example, there are three 
 photochemical substances, one decomposed by a 
 relatively slow vibration rate, another by a more 
 rapid vibration rate, and so on. And in the audi- 
 tory mechanism there is the basilar membrane, 
 capable of vibration in parts in sympathy with 
 different rates of vibration of the air. The 
 answer to this question concerning the taste sense 
 is peculiarly difEcult, in that it is impossible to 
 stimulate individual taste buds, and even difficult 
 to stimulate a single papilla, which may contain 
 many buds. And then it must be further borne 
 in mind that each bud contains many nerve end- 
 ings, so that what is stimulated in experimental 
 work is really a very complex portion of the sense 
 organ. 
 
 As mentioned in another connection, certain 
 papillae when stimulated with various substances 
 respond to but one, e.g., sweet, sour, bitter, or 
 
114 THE SENSE OF TASTE 
 
 salt, while others respond to two or three stimuli. 
 Further, it is well known that certain portions of 
 the tongue when stimulated produce a predomi- 
 nance of certain kinds of taste sensations. On 
 the other hand, an examination of the taste buds 
 or of the nerve endings within the taste buds 
 shows no differences among them. Still, in this 
 respect taste does not differ from sight. The 
 cones of the retina, which are sensory ends of 
 vision, show no differences in structure, and it is 
 generally believed that all of the elementary sen- 
 sations can be produced by the stimulation of one 
 single cone. If it be true that the nerve fibrils 
 in the taste buds themselves receive the stimulus, 
 then any specific characteristics of the receiving 
 mechanism would have to be looked for in these 
 nerve endings. 
 
 Oehrwall has accounted for the facts of the 
 specific sensitivity of different parts of the tongue 
 and of different individual papillae mentioned 
 above by the assumption that each taste bud has 
 a specific function and that certain papillae of the 
 tongue have buds all of one sort, other of two 
 sorts, and so on. Nagel prefers to modify this 
 view to the extent that each taste bud is capable 
 of arousing every elementary sensation, but is 
 adapted to respond best and easiest to a certain 
 specific stimulus with a certain elementary sensa- 
 tion. This view is analogous to that of the visual 
 
FUNCTION OF TASTE MECHANISM 1 1 5 
 
 photochemical substances which, according to the 
 Helmholtz theory, were each sensitive to all wave 
 lengths of light, but riot equally. 
 
 The previous review of theories does not con- 
 sider the possibility of the specific energy of brain 
 centers, rather than of the peripheral sense mech- 
 anism — that is, the possibility that the sensation 
 qualities, sweet, sour, etc., may be due to struc- 
 tural characteristics of brain centers, rather than 
 of sense organs. This is a question which is un- 
 solved for other senses and consequently is not 
 peculiar to taste. The present tendency seems 
 to be toward attributing the different sensation 
 qualities to the sensitivity of the sense organ, or 
 else to divide it between brain center and sense 
 organ. The following facts are considered as 
 indirect evidence of the specific energy of the sen- 
 sory ends of taste : ( i ) The distribution of taste 
 sensitivity over the tongue. (2) The effect of 
 certain drugs, e.g., cocaine, which destroys the 
 taste sensations one at a time. This suggests that 
 the sensory ends that have to do with the different 
 sensations are differently affected by the drug. 
 (3) The fact that the same substance as it passes 
 over the surface of the tongue arouses different 
 sensations, e.g., sodium sulphate, which is sweet 
 on the tip and bitter on the back of the tongue. 
 
CHAPTER IX 
 
 The Development of Taste in the 
 Individual 
 
 Development Before Birth 
 
 The structures concerned with the taste sensa- 
 tions develop early in the life of the human 
 embryo. As early as the twelfth day the rapid 
 development of the head end of the embryo 
 causes an infolding of the ectoderm (outer layer 
 of the embryo), which later forms the mouth and 
 nasal cavities. And about the twelfth week the 
 mouth structure is fairly complete. It has at this 
 stage become separated from the nasal cavity 
 through the growth of the hard and soft palate. 
 
 At the twelfth week the tongue is also fairly 
 well developed as a single organ, although origi- 
 nating from three or four separate parts which 
 grow together. The anterior two-thirds of the 
 tongue — that is, all of that portion back to and 
 including the rows of circumvallate papillae of the 
 adult tongue, — grows from the floor of the orig- 
 inal mouth structure. It is in this portion alone 
 that papillae are to be found. At the end of the 
 
 xi6 
 
TASTE IN THE INDIVIDUAL 117 
 
 fourth week the circumvallate papillae begin to ap- 
 pear and at the twelfth week the fungiform and 
 filiform papillae begin to appear. 
 
 About the fifth month there begins a multiplica- 
 tion of the cells in the germinative layer of the 
 epithelium covering the tongue, which marks the 
 beginning of the taste buds. At the eighth month 
 the development has advanced so far that the gus- 
 tatory cells can be distinguished from the support- 
 ing cells, and the whole taste bud has separated 
 itself somewhat from the surrounding tissue. The 
 nerve fibrils found in the fully developed taste 
 bud come into connection with the gustatory cells 
 very early in their history — in fact, the presence 
 of the fibrils is considered by some authorities as 
 the stimulus to modification of the epithehal cells 
 into those special forms and the consequent for- 
 mation of the taste buds. 
 
 At birth the most essential parts of the taste 
 mechanism seem to be fully developed and able 
 to function. The taste buds and the taste pores 
 by which they communicate with the tongue sur- 
 face have the same structure as in the adult. The 
 papillae, however, according to Stahr, have not 
 attained the adult form. From an examination 
 of the tongues of a large number of newborn 
 babies he reports that the foliate and the circum- 
 vallate papillae are not complete, the depression 
 surrounding the latter being broken in places and 
 
11 8 THE SENSE OF TASTE 
 
 one papilla not clearly distinguished from others. 
 The fungiform type, too, does not at this stage 
 resemble a toadstool, as it does in the adult, but 
 they are more like very large filiform papillae. 
 Microscopical examination shows both of these 
 types of papillae to carry their taste buds on the 
 top, rather than far down upon their sides. In 
 no case did Stahr find a fungiform papilla with- 
 out one or more taste buds. 
 
 The distribution of the taste buds over the sur- 
 face of the mouth cavity of the fetus and the 
 newborn, as determined by histological examina- 
 tion and experiment, is very extensive, as com- 
 pared with the adult. The presence of taste buds 
 and of taste sensitivity has been reported upon 
 the arches of the palate, over the whole dorsal 
 surface of the tongue, and the inside of the 
 cheeks. Buds are especially numerous upon the 
 tip of the tongue. 
 
 Development of Taste in Infancy and Childhood 
 
 After birth certain changes occur in the taste 
 organs. During the whole period of lactation 
 the tip of the tongue remains especially sensitive 
 to sweet stimuli, a valuable condition for the pro- 
 motion of the food-taking reactions in the infant. 
 During this period also the whole superior sur- 
 face, of the tongue remains sensitive to taste 
 stimuli, but with increasing age there appears a 
 
TASTE IN THE INDIVIDUAL 119 
 
 region of Insensitivity just back of the sensitive 
 tip. At the same time there is said to be an in- 
 creasing sensitivity upon the edges of the tongue. 
 The, insensitive zone differs in extent for the 
 different elementary tastes, but is fairly large for 
 all. These progressive changes in sensitivity have 
 been explained as the result of the appearance of 
 the teeth and their importance in the bodily 
 economy. While the individual lacks teeth and 
 subsists on a milk diet the process of nourishment 
 is best accomplished by having the food pass 
 directly back over the superior surface of the 
 tongue until it reaches a point where the swallow- 
 ing reflexes are set up. However, after the teeth 
 '/appear and mastication of food is necessary, then 
 it is better that the food should pass from the 
 tip of the tongue to either side, where it will come 
 between the teeth 1 Thus, seeking the maximum 
 taste sensation from the food is equivalent to 
 placing it in a position to be thoroughly masti- 
 cated. Further, the presence of food, and espe- 
 cially sour food, upon the sides of the tongue 
 forms the stimulus to the flow of saliva, a neces- 
 sary factor in preparing the food to be swallowed 
 and digested. Now, if the superior surface of 
 the tongue were highly sensitive to taste stimuli 
 there would be a tendency to hold the substances 
 upon that part in order to prolong the pleasure, 
 thus retarding the proper mastication of the food. 
 
I20 THE SENSE OF TASTE 
 
 A simpler explanation of the decreasing sensi- 
 tivity of the upper surface of the tongue and the 
 increasing sensitivity of the sides is the fact that, 
 after the teeth appear, chewing would tend to 
 collect the dissolved food substances at the sides 
 of the tongue, rather than upon its dorsal surface, 
 hence the greater importance of the taste buds 
 upon the sides of the tongue. 
 
 It is difficult to see why the inside of the cheeks 
 should be sensitive to taste stimuli in young chil- 
 dren and why this sensitivity should be lost in the 
 adult. Titchener has suggested that its presence 
 in children may account for their desire to take 
 large mouthfuls of food, thereby getting max- 
 imum taste sensation. 
 
 Whatever the biological interpretation of these 
 changes may be, certain structural changes have 
 been noted which seem to account in part, at least, 
 for the changed sensitivity. The circumvallate 
 and foliate papillae become complete during the 
 first few months and the taste buds, instead of 
 being located upon the top of the papillae, are 
 now found rather low down upon their sides. 
 The change in the fungiform type is more pro- 
 nounced. These, more or less conical in shape at 
 first, begin to acquire an enlarged head (by the 
 growth of secondary papilla, according to 
 Stahr). Not only this, but the taste buds in all 
 of them are now found to have moved from 
 
TASTE IN THE INDIVIDUAL 121 
 
 the top to the sides of the papillae, and many of 
 the buds have disappeared altogether, some of the 
 papillae apparently losing all taste function. 
 There are various opinions as to how the buds 
 change their position or are lost, but none of 
 these are well enough established to need de- 
 scription. 
 
 Thus, by the completion of growth in the cir- 
 cumvallate and the foliate papillse and by the de- 
 generation of the fungiform (loss of taste buds) 
 the region of greatest sensitivity is transferred 
 from the tip to the sides and back part of the 
 tongue, while the zone just back of the tip be- 
 comes entirely taste blind. 
 
 Taste in the Adult 
 
 The most striking characteristics of taste in 
 the adult as compared with that of the child, 
 then, is what appears to be a gradual reduc- 
 tion in the extent of distribution of taste sensi- 
 tivity and a shifting of the region of the 
 greatest sensitivity. No doubt there are other 
 changes, e.g., a general reduction in delicacy of 
 taste analogous to the sort of change which is 
 noted in the other senses as age advances. In 
 extreme old age such a condition is quite pro- 
 nounced. In hearing, for example, there is not 
 only a dulling sensitivity but a shortening of the 
 range of audible pitches, especially in the region 
 
122 THE SENSE OF TASTE 
 
 of the higher pitches. So, on the tip of the 
 tongue, sensitivity may be very much reduced or 
 disappear entirely. These changes in taste are 
 not commonly brought to one's attention as are 
 those of sight and hearing, because they affect 
 our life less vitally. But there is little doubt that 
 careful tests would reveal them. 
 
 Structural and Functional Differences Among 
 Individuals 
 
 It has been_s uggested tha t.individHal&-4iffer 
 CQjis^eraH5lin_jhe. distribution jnid^Junction of 
 thfiirj^aste mech^nisiiL In tfife^ search for general 
 laws these variations within the limit of normality 
 have been looked upon as troublesome exceptions 
 and not of much interest. And these differences 
 are no doubt responsible for the lack of agree- 
 ment' among investigators on many points. For 
 instance, there are persons whose senskiyity^pn 
 the tij) of the tongue is sp_poor that sweet jastes 
 c^ULhe arousedlpnly^with the aidjof tongue move- 
 qients. This and other similar cases TiavegTven 
 cause for theJbeHef_in_riie_ nec^sity^f tongue^ 
 movements fq^arousing^all^ste- sensatio nsVSbme 
 invesllgafors have found the tonsils and the uvula 
 sensitive, while others have found them insensi- 
 tive. When one finds such conflicting statements 
 from men like Nagel and Kiesow, individual dif- 
 
TASTE IN THE INDIVIDUAL 123 
 
 ferences seem a plausible explanation. No sp^ial 
 studies have been made of these individual differ- 
 ences. Consequently, a bout a ll jhat one can say 
 is thatjthe^ distribution qf t hT ta ste 1 5u3s"in_ ^f^ 
 ferent people is subject to^ considerab le variatio n 
 and that on this account one cannot _definitely 
 mark jout„the limits of their distribution jvghi(;h 
 shall hold jf or all persons. The same is true of 
 the disitiLibutipn of sensitivity to specific_tasi:e 
 stimuliT sweet, souri bitter, and salt substances'. 
 Such vague" statements as are usually made, 
 namely, that sweet is best tasted upon the tip of 
 the tongue, sour upon- the sides, bitter upon the 
 back, and salt over nearly the whole tongue, are 
 true, but when one attempts to assign definite 
 limits to these regions then great individual differ- 
 ences appear. 
 
 Individual Differences Due to Pathological 
 Changes 
 
 More extreme variations in taste are frequent 
 as aiTaccompaniment of dise~aTe'ofcO ngenitaf md- 
 f o^ination^f the'^rebrum. These variations 
 may be in .tke ,aature of ^^ence of sensitiveness, 
 dull'Xhypo) sensitivilbjvor very hijghXUyPer) sen- 
 sitivity^ Only one case, so far as we have found, 
 has been reported of congenital taste blindness, 
 either for all taste sensations or for one or two 
 of them, such as would correspond to hereditary 
 
124 THE SENSE OF TASTE 
 
 color blindness of the various sorts. The ap- 
 parent absence of taste in certain idiots is not a 
 form of taste blindness to be compared with color 
 blindness. Such persons will eat sulphate of 
 quinine with as much enjoyment as sweet food, 
 but so will they try to eat wood or stones or 
 paper. Nor are the cases, which are more or 
 less common, of dulled taste sensitiveness as a 
 result of cerebral malformation to be compared 
 with real color blindness, which, as far as is 
 known, at least, depends upon no such cerebral 
 abnormality. 
 
 There are cases of acquired taste blindness, 
 either general or for special qualities, which re- 
 semble in general character acquired color blind- 
 ness. In both senses the blindness results from 
 pathological changes in the sensory mechanism, 
 either in the sense organ, its centers within the 
 brain, or its connecting nerve trunks. The nature 
 of the sensory defect depends upon the extent of 
 the pathological change and its location. Thus," 
 there may be general taste blindness if both of 
 the cerebral centers are involved, a defect on only 
 one side of the tongue if one cerebral hemisphere 
 is involved. And if the disturbance is in the nerve 
 trunks, only the anterior two-thirds of the tongue 
 may be affected, or only its posterior third. 
 Again, if the lesion is in the sense organ itself, 
 one or more specific taste qualities only may be 
 
TASTE IN THE INDIVIDUAL 125 
 
 lost, or all qualities for a very small portion of 
 the topgue. These latter cases are of much im- 
 portance in developing an adequate theory of 
 taste function. Nagel describes a case in which 
 all sorts of taste stimuli produced only a sensation 
 of salt on one side of the tongue, while on the 
 other side taste was normal. This peculiar condi- 
 tion was followed by a total loss of sensitivity on 
 the affected side. 
 
 Epileptics are said to show taste abnormalities 
 of varying character after an attack, and lasting 
 for hours in some cases. There is usually a loss 
 or dulling of the sense, most prominent for salt 
 and least noticeable for bitter. Such conditions 
 are not peculiar to the taste sense, for there is 
 usually a disturbance of the other special senses 
 also after an epileptic attack. 
 
 All sorts of taste abnormalities are found in 
 hysteria, but little is known of their underlying 
 causes in the taste mechanism. There may be 
 either hyper- or hyposensitivity, although the lat- 
 ter is more common ; and both sides of t he tongue 
 or only one side may be affected^ or_ even only a 
 smairjrortIon~6r~tEe tongue jiuix_be inyolyed. 
 Here, too, the taste abnormalities are accom- 
 panied by disturbances of the other senses. 
 
 Criminals, especially those recognized as de- 
 generate, show taste abnormalities, usually ex- 
 treme dullness of taste, along with the same sort 
 
126 THE SENSE OF TASTE 
 
 of defect in the other senses. Attempts have 
 been made to find a positive correlation between 
 keenness of taste and number of stigmata of de- 
 generation, but with no success. 
 
 Any conditira^ affecting the muc ous lining of 
 thejiouth^cayitYjnay be expectedj omodify taste 
 sensitivity. Janinsta qce, burning the tongue with _^ 
 aT^tjdfmk will destrqjr^taste for a tijne. ,TumoEs 
 and abnormji jhickening-oi the epithelium ^„the 
 tongue,, will .likewise- disturiTJKi~tirsteriunction. 
 These effects arejcle^arly due ^_jijdirect_ action, 
 uponTBeTasSTBuds. orJtKe3ustatorj[_pores, and 
 may be local or general in character. Under this 
 head might be mentioned the effects of drugs ap- 
 plied to the tongue surface, but they have been 
 discussed elsewhere. Hallucinations of taste like- 
 wise, of which there are a great variety, have 
 been described in another connection. 
 
 Racial Differences in the Structure atfd Function 
 of the Taste Organs 
 
 A number of races, e.g., Negroes, Japanese, 
 Europeans, etc., have been studied to determine 
 differences in the taste mechanism, but little of 
 significance has been found. The number of 
 papillae upon the tongue is just about the same in 
 every case. The slight differences of size and 
 arrangement of the papillae, especially the circum- 
 
TASTE IN THE INDIVIDUAL 127 
 
 vallate type, are not such as to be of much impor- 
 tance from the functional point of view. The 
 variation in these respects is so large within any 
 one racial group that there is little likelihood of 
 finding significant racial differences. 
 
CHAPTER X 
 
 Evolution of Taste 
 
 Sensitivity of the Unicellular Organisms 
 
 The study of the sense organ of taste in adult 
 human beings consists of an examination of the 
 taste sensations resulting from controlled stimu- 
 lation of limited parts, supported by the micro- 
 scopical examination of the structures found in 
 the regions in which these taste sensations can be 
 aroused. The relation of cause and effect is then 
 assumed. Neither method taken alone will suf- 
 fice, as there always remains the possibility of 
 function in the absence of definitely recognized 
 taste structures and also the possibility of the 
 presence of functionless structures. The diffi- 
 culties and uncertainties arising in this combined 
 study of structure and function have been dis- 
 cussed in earlier chapters. 
 
 But if the determination of the taste organs 
 and their localization offers difficulties in the adult 
 human being, these are multiplied many times 
 when the study is carried to the lower animals. 
 The method of stimulation Is greatly limited, to 
 
 128 
 
EVOLUTION OF TASTE 129 
 
 what extent depending upon the kind of animal 
 studied, because the results of the application of 
 stimuli must be interpreted from the forms of 
 behavior exceedingly crude, compared with the 
 language behavior of man. This handicap in the 
 study of taste is great, as compared with sight 
 and hearing, at least, on account of the extremely 
 close relation between the taste and smell organs 
 In position and in the nature of their appropriate 
 stimuli. In case of certain of the lower animals 
 the assumption of distinct states of consciousness 
 corresponding to our experiences of taste and 
 smell is unwarranted, as is even the assumption 
 of any consciousness at all. 
 
 The study of taste structures reduces itself 
 largely to the search for sense organs resembling 
 those of man, and in the same neighborhood as 
 they are found in man. Here again the difficulty 
 is especially great in taste, because the taste 
 organs even in man are not very highly differen- 
 tiated from other structures, and the really essen- 
 tial part of the organ is not definitely known. 
 (See Chapter VI.) In the search for taste In- 
 lower animals one must rely much upon the ex- 
 pectation of finding the taste mechanism in the 
 mouth or its immediate neighborhood. Struc- 
 tures found here and not known to function other- 
 wise are likely to be looked upon as taste organs. 
 These assumptions from location are then tested 
 
I30 THE SENSE OF TASTE 
 
 by stimulation of the parts with sapid substances 
 and looking for characteristic responses, and fur- 
 ther by extirpating these organs and noting the 
 effect upon behavior. Other criteria of sensi- 
 tivity, which can be used especially in the study 
 of sight and hearing, such as rate of fatigue, re- 
 action time to stimulation, and the like, are of 
 little use on account of the above-mentioned close 
 relation between taste and smell. 
 
 When looked at from the evolutionary point 
 of view, all of the senses are seen to have de- 
 veloped through modification of the sensitivity of 
 a single structure, the cell, with its additional 
 properties of conductivity and motility. In the 
 simplest living organisms, for instance, one finds 
 sensitivity to consist in the irritability common to 
 all living cells, and the sense organ to be repre- 
 sented by the whole cell. Still, the amceba, one 
 of these unicellular organisms, reacts differently 
 to the contact of food substances and to purely 
 mechanical stimulation. And the white corpuscles 
 of the blood in the human body are said to adjust 
 their behavior according to the chemical composi- 
 tion of their surroundings. So, even in this 
 earliest stage of evolution, before any differentia- 
 tion of structure appears, one sees a reaction 
 analogous to the taste reactions of the higher 
 animals. 
 
EVOLUTION OF TASTE 131 
 
 " The Chemical Sense " 
 
 In the simpler multicellular organisms, which 
 develop by cell division and multiplication from a 
 single cell, the cells differ from the original type 
 and from each other in position, structure, and 
 function. In the course of growth the organism 
 originally spherical in shape becomes modified by 
 irregular growth of cells, producing folds and 
 prominences. Cells are crowded out of shape; 
 some lie at the base of a depression protected 
 from stimulation; others occupy positions which 
 make them especially liable to be acted upon by 
 such stimuli. In the course of these modifications 
 some of the cells become especially adapted for 
 receiving Impressions, others for conducting or 
 transmitting these impressions to various parts of 
 the organism, others for produdng movements 
 of the organism. It is with the first type of cell 
 that we are concerned, the receptor mechanisms. 
 They are In the simpler organisms, adapted to 
 receive two sorts of stimulation, mechanical and 
 chemical. In fact, through the whole series of 
 multicellular organisms such reactions to me- 
 chanical and chemical stimuli have been noted 
 more or less definitely, although special sense 
 organ structures have in many cases not been dis- 
 covered. This Is especially true for the reactions 
 to chemical substances. It is customary to speak 
 
132 THE SENSE OF TASTE 
 
 of the " chemical sense," to signify these re- 
 sponses to chemical substances, without any at- 
 tempt to differentiate between smell and taste. 
 Obviously, in the case of organisms which live in 
 a fluid environment, this chemical sense might be 
 called taste, since it would correspond in a way 
 to that sense in man, for which the adequate 
 stimulus is a fluid. But since it is a " distance 
 receptor," in that objects at a distance can pro- 
 duce responses, probably by diffusion of sub- 
 stances in the fluid, it might also be looked upon 
 as more nearly resembling the smell sense. In 
 most cases structure offers no help in settling the 
 matter. 
 
 In the medusa, or jellyfish, one of the earliest 
 forms in which a nervous system and sense organs 
 are found, the tentacles are especially sensitive to 
 chemical stimuli, much less so to mechanical 
 stimuli. To the former they respond by shorten- 
 ing and twisting themselves about the object. As 
 for sense organs in these parts, there are small 
 club-shaped papillae in the neighborhood of the 
 tentacles, differing somewhat in character in the 
 different species. These papillae contain a narrow 
 canal lined with thick cylindrical cells. As far 
 as both structure and function are concerned, 
 they may be considered either as taste or smell 
 organs. 
 
 In the flat worms, where a nervous system with 
 
EVOLUTION OF TASTE 133 
 
 a rudimentary brain is found, the reaction to 
 chemical stimulation is not clear. This organism 
 has specialized responses, among which is a move- 
 ment toward food placed near it. But whether 
 this is a reaction to chemical stimuli alone or 
 combined with mechanical is not known. No taste 
 organs have been found. Pits or depressions 
 found on the lateral surface of the anterior end 
 of the worm, and supplied with nerves from the 
 brain, have been regarded as olfactory rather 
 than as taste organs. 
 
 In the annelid group, of which the earthworm 
 may be taken as an example, there are well- 
 defined chemical reactions, which more nearly re- 
 semble taste reactions than the cases previously 
 mentioned. Here a positive reaction to food sub- 
 stances seems to occur only when these substances 
 come into contact with the body. For instance, 
 the characteristic burrowing reactions of the 
 earthworm are not aroused by placing filter paper 
 soaked in manure near them, but only when the 
 paper is actually in contact with the body. Nega- 
 tive reactions, however, to strong chemical stimu- 
 lation may take place without contact. Attempts 
 have been made by Parker and Metcalf to show 
 specialized taste reactions to different chemical 
 substances by measuring the latent time in the 
 responses to various substances brought into con- 
 tact with the body. From such evidence as this it 
 
134 THE SENSE OF TASTE 
 
 would appear that earthworms have specialized 
 reactions to the chlorides of sodium, potassium, 
 lithium, and ammonium, which are indistinguish- 
 able to the human taste sense, with their common 
 salt taste. These results are interpreted as indi- 
 cating qualitatively different ejects of the stimuli. 
 In these organisms it has been possible to discover 
 taste organs, distinct from the olfactory organs. 
 They are described as cup-shaped organs, which 
 may be either depressions or prominences. They 
 occur in large numbers and are widely scattered 
 over the body. They are said, however, to be 
 especially numerous at the edges of the mouth 
 and within the mouth cavity. 
 
 The Crustacea, among which are the crabs and 
 the lobsters, characterized by their hard shell- 
 like covering, show certain specific reactions to 
 chemical substances when these come into contact 
 with the parts of the body near the mouth. Re- 
 actions to chemical stimuli applied to any part 
 of the body of the crayfish have been reported 
 by Bell. The positive reactions were such as to 
 bring the substance toward the mouth and the 
 negative reactions such as to remove the sub- 
 stance. Responses to such substances at a dis- 
 tance are uncertain. But it is difficult to differen- 
 tiate between possible smell and taste reactions. 
 The sense organs in these organisms are usually- 
 located upon the antennae, or feelers, in the neigh- 
 
EVOLUTION OF TASTE 1^$ 
 
 borhood of the mouth. Here there is a different 
 kind of response to chemical and mechanical 
 stimulation. No structures with a specific taste 
 function have been described, although smell and 
 tactile organs have been localized. 
 
 In the organisms described above, the chemical, 
 or, more specifically, the taste, sense is a food 
 sense, — edible and inedible substances causing re- 
 actions of different character. The reactions to 
 stimuli within the edible group, however, show no 
 variation. In the insects, especially the ants, bees, 
 wasps, etc., there seem to be qualitative differ- 
 ences in the effect produced by chemical sub- 
 stances. It is by means of this chemical sense that 
 bees and ants are able to find food at a distance, 
 to return to their homes under all sorts of ad- 
 verse conditions, and to distinguish nest mates 
 from enemy intruders. But, since these are all 
 reactions to stimuli at a distance, they must be 
 attributed to the smell sense, rather than to the 
 taste sense. But in the case of these organisms a 
 sharp distinction between smell and taste seems 
 possible. Forel and others have offered honey 
 mixed with strychnine to ants, who seized it 
 greedily, indicating an olfactory sensibility. But 
 immediately after the honey had touched the 
 mouth parts, avoiding reactions, such as to re- 
 move the substance, followed, indicating sensi- 
 tiveness to the bitter substance. Wasps and bees 
 
136 THE SENSE OF TASTE 
 
 will make the same sort of responses if distasteful 
 substances which are inodorous are mixed with 
 pleasant, odorous substances. The sensitivity to 
 tastes varies considerably in different insects, be- 
 ing very great in bees and ants. From such 
 experiments as the above it has been concluded 
 that the smell organs are located on the antennas 
 and that the taste organs are located on the lips 
 and in the mouth. Microscopical examination 
 shows that in all insects the tongue and inside of 
 the mouth are covered with minute pits, or de- 
 pressions. In each pit there is a minute hair, or 
 rod. Some observers say that this rod is hollow 
 and perforated at the end, thus communicating 
 with the nerve which ends at its base. Other 
 observers say that there is no perforation upon 
 the end of the hair. However this may be, there 
 seems to be no doubt that these are the taste 
 organs. The same type of structure has been 
 reported on the proboscis of the bumblebee, the 
 hive bee, and the common fly. They are said to 
 resemble a hollow hair, the channel communicat- 
 ing with a nerve fiber at its base. In the insects, 
 then, we find the earliest definitely specialized 
 taste mechanism. 
 
 Chemical Sense in Fishes 
 
 In the fishes, again, the distinction between the 
 senses of smell and taste becomes more difficult, 
 
EVOLUTION OP TASTfi 13^ 
 
 on account of their fluid environment. But, dis- 
 regarding the distinction between smell and taste, 
 the general chemical sense plays a very important 
 part in the life of the fish. Now, some observers 
 have included all of this sensitivity to chemical 
 substances within the sense of smell, while others 
 have attributed a part of it to a taste mechanism. 
 As representative of the latter, Herrick's con- 
 clusions are of interest: " In fishes the gustatory 
 system is much more extensively developed than 
 in mammals, especially the vagal part which sup- 
 plies the taste buds in the gill region. In some 
 species of fishes, moreover, taste buds appear in 
 great numbers on the outer skin, and these are In 
 all cases innervated from the seventh cranial 
 nerve. In the common horned-pouts, or catfishes, 
 and in the carps and suckers these cutaneous taste 
 buds are distributed over practically the entire 
 body surface, and especially on the barblets. 
 . . . These sense organs and their nerves are 
 entirely independent of those of the lateral line 
 system, and of the ordinary tactual system, 
 though the gustatory and tactual systems have 
 been shown experimentally to cooperate in the 
 selection of food." 
 
 Herrick determined by experiment that the 
 sense organs thus generally distributed over the 
 body of the catfish really had a taste function. 
 Food placed at a distance from the fish produces 
 
138 THE SENSE OF TASTE 
 
 only restless movements, indicating that the eyes 
 do not direct them to it. But if food comes into 
 contact with the mouth parts, or, in fact, any part 
 of the body, it is immediately seized. To show 
 that this reaction is not alone due to tactual stimu- 
 lation, the tactual organs were first stimulated 
 with cotton wool, which produced the character- 
 istic seizing reaction. But after stimulation was 
 continued for a while reaction no longer followed. 
 If at this point the cotton wool be soaked with 
 meat juice, the seizing reaction is again set up. 
 Adaptation to tactual stimulation has taken place, 
 leaving the taste organs to function alone. To 
 show further that the responses did not depend 
 on olfactory stimulation, the olfactory nerves of 
 certain fishes were cut. When the experiment 
 was performed, after recovery from the opera- 
 tion the responses were the same as in normal 
 fish. 
 
 The experiments of Parker show further that 
 the mouth and external surface of the body of 
 certain fishes are sensitive to sour, salt, and alka- 
 line solutions. Sheldon obtained about the same 
 results. The external skin covering is not sensi- 
 tive to sugars. The tongue of fishes presents a 
 smooth, gray, dorsal surface, devoid of elevations 
 or papillae, which characterize the tongues of 
 many other organisms. Nor is it a mobile organ 
 in comparison with other species. On the whole, 
 
EVOLUTION OF TASTE 13^ 
 
 the tongue itself seems little adapted for arousing 
 taste sensations. 
 
 The system of " lateral line " organs of fishes 
 have at times been thought to be concerned with 
 the chemical sense. This is probably not the case, 
 although their exact function Is a question still 
 under dispute. 
 
 In a general way, the taste buds, or sense 
 organs of taste of fishes, resemble those of the 
 human being. They are either flask- or cup- 
 shaped, and are composed of two types of cells, 
 called supporting cells and taste cells. The lat- 
 ter cells end peripherally in a hair or bristle, just 
 as the same kind of cell in the human taste bud. 
 
 Land-Dwelling Animals 
 
 There seems to be no experimental evidence 
 for a specific sense of taste in amphibia, or rep- 
 tiles. But sense organ structures have been de- 
 scribed upon the tongue and soft palate of the 
 frog, where they are said to occur in hundreds. 
 They are disc-shaped structures, made up of sev- 
 eral kinds of cells, which correspond to the real 
 taste cells and supporting cells of the human 
 sense organ. The taste cells end peripherally in 
 several hairs or bristles, and at their central end 
 make connection with nerve fibers. In the reptile 
 group there is neither experimental evidence of 
 taste sensitivity nor anatomical evidence of the 
 
I40 THE SENSE OF TASTE 
 
 presence of taste corpuscles on the tongue or in 
 the mouth cavity. 
 
 The experimental evidence for the taste sense 
 in birds is slight. It certainly is greatly over- 
 shadowed by the keen senses of sight and hear- 
 ing. Birds seem to represent one case, however, 
 in which taste is more important than smell. 
 Taste sensitivity for different chemical substances, 
 in the case of young chickens, at least, seems clear 
 from certain studies of instinct and learning, in 
 which they accept certain kinds of food and reject 
 others after tasting them. In considering the 
 sense of taste in birds it must be remembered that 
 most of them swallow their food without chewing 
 it or without having it reduced to liquid form 
 through mixture with saliva. The tongue, which 
 varies in character considerably in different types 
 of birds, is in most cases covered with a horny 
 coat. Numerous hard papillae are found upon its 
 surface. Microscopical examination of these 
 papillae shows nothing which can correspond to 
 taste buds or to gustatory cells. The parrot is 
 said to form an exception to most birds, in that It 
 has a relatively soft and fleshy tongue, with 
 numerous papIUas, and also in that It chews its 
 food. 
 
 In the duck, which has a large tongue, there 
 are certain portions which lack the hard covering 
 common to birds' tongues. Here, in addition to 
 
EVOLUTION OF TASTE 141 
 
 a large number of tactile corpuscles, there are 
 groups of cells which resemble somewhat true 
 taste corpuscles. The peripheral ends of their 
 cells reach the surface of the mucous covering of 
 the tongue. The cells do not end in the bristle, 
 or hair-like, formation, as those of the human 
 taste cells, but in a pointed elongation of the pro- 
 toplasm. Experimental evidence of the function 
 of these structures is lacking. 
 
 Taste sensitivity and the structure of the taste 
 organs differ greatly in the mammals, but there 
 seem to be two characteristics in common, namely, 
 the localization of the taste corpuscles within the 
 mouth and the importance of the tongue in arous- 
 ing taste sensations. The character of the mucous 
 lining of the mouth also shows great variation 
 in the number of papillae and the taste buds which 
 theytontain. The number of papillae varies from 
 two or three in the marsupials and four in the 
 elephant to an extremely large number in rodents, 
 e.g., the rat. The papillae are in general quite 
 similar to the three most common forms in the 
 human taste organs, the circumvallate, the fungi- 
 form, and the filiform, and have about the same 
 location in relation to each other. The greatest 
 difference is in the prominence of the fourth type, 
 the foliate papilla in certain mammals, as com- 
 pared with man. These are seen best in the rab- 
 bit, as folds directed downward and forward on 
 
142 THE SENSE OF TASTE 
 
 the sides of the tongue in its posterior portion. 
 They have been considered to result from the 
 great number of papillae which throw the mucus 
 into folds. Each foliate papilla is composed of 
 a number of parallel ridges, each ridge in turn 
 being composed of papillae of the fungiform type. 
 Between the ridges there are narrow ditches. It 
 is in the side walls of these that the taste cor- 
 puscles are found in greatest numbers. Thus, 
 these ditches are analogous, in function at least, 
 to those of the circumvallate papillae. Their 
 origin, however, seems to be different from that 
 of the circumvallate. In the monkey one finds 
 less prominent folds on the sides of the tongue, 
 rich in taste corpuscles, which represent the foliate 
 papillae. 
 
 The taste corpuscles themselves have about the 
 same characteristics in all mammals as in man. 
 There are differences in size, to be sure, but their 
 structure is the same, and the supporting cells, 
 gustatory cells, and nerve fibers are present in 
 them all. 
 
 This survey of taste in the animal kingdom 
 suggests the conclusion that the taste organs rep- 
 resent a modification of the original skin sensi- 
 tivity or touch sense, and surely a slight modifica- 
 tion when compared with the senses of sight and 
 hearing. A certain resemblance has been re- 
 marked by Wundt and others between the touch 
 
EVOLUTION OF TASTE 143 
 
 corpuscles and the gustatory corpuscles. His in- 
 terpretation is that the whole body was originally 
 endowed with the touch sense, while certain parts 
 being affected continually by specific sorts of 
 stimuli, became adapted to them by undergoing 
 modifications of structure. The head or mouth 
 end of the animal was more subject to chemical 
 stimulation, and the adaptation of the tactile 
 organs to this particular form of stimulation re- 
 sulted in the development of the senses of taste 
 and smell. To consider taste as one of the lower 
 senses, in the sense of being least highly developed 
 and the earliest to appear, is justified from this 
 survey of the evolution of the taste sense, if from 
 no other point of view. 
 
CHAPTER XI 
 
 Gustatory Imagination and Memory 
 
 The Nature and Frequency of Mental Images 
 
 It is a familiar fact that in one way or another 
 and in different degrees to different individuals 
 it is possible to have sensory experiences without 
 the actual presence of their accustomed stimuli. 
 Thus, many people can recall " in their mind's 
 eye " the colors of objects, their shape and struc- 
 ture, when they are no longer in the presence of 
 the object thought of. Or, " in their mind's ear," 
 they can hear the blare of a trumpet, the voice 
 of a friend, the hissing of steam, when no corre- 
 sponding stimulus is present to the ear. Similarly, 
 " in imagination " many can experience the tac- 
 tual feel of velvet, the odor of onions, the warmth 
 of sunshine, the ache of a tooth, the nausea of 
 seasickness. 
 
 " Thus, I can call up in my mind's eye, more or 
 less vividly, my boyhood home, and seem to see, 
 though more obscurely than if I were present on 
 the spot, the house and barn, the grape arbor, the 
 
 144 
 
IMAGINATION AND MEMORY 145 
 
 garden, even ray little bookcase in the library. I 
 can smell the honey in the bee boxes, and can hear 
 the general hum and stir of the hive. I can do 
 this because I can call up images of these past 
 experiences. Or, by putting together the images 
 of wheels, sails, birds, and ropes which I have 
 actually seen I can create in my mind's eye an 
 aeroplane of a pattern which has never yet been 
 constructed." This constructive performance 
 would constitute " imagination " as distinguished 
 from mere " imagery." 
 
 These images of imagination are not to be con- 
 fused with the after sensations which we have 
 already described. They may be experienced 
 days, or even years, after the first application of 
 the original stimulus. Nevertheless, these " men- 
 tal images," or " centrally exdted sensations," 
 are described as essentially sensory in character, 
 — they have the attributes of all sensory experi- 
 ences, such as intensity, extensity, duration, clear- 
 ness, locality, quality, and modality. In fact, 
 observers have been found for whom these men- 
 tal images were so realistically sensory that actual 
 negative after sensations, in the case of visual 
 images, have been reported as following upon 
 them. 
 
 In the case of many individuals, these experi- 
 ences of objects in their absence are relatively 
 rare and obscure, and in some cases, indeed, are 
 
146 THE SENSE OF TASTE 
 
 so obscure as to lead the individual to deny the 
 existence of such experiences. In still other cases 
 the centrally excited sensations, the mental images, 
 are experienced in their vivid and, apparently, 
 immediately sensory form only under special 
 conditions, as in dreams, hallucinations, drowsi- 
 ness, or fatigue, or under the influence of special 
 drugs. It has appeared from the study of mental 
 images that, in so far as they are present, they 
 are not equally reported in the different modes of 
 sensation. Visual images in some cases, auditory 
 images in other cases, and motor images in still 
 others, have seemed to be so specially frequent, 
 vivid, or easily aroused that at one time it was 
 customary to classify individuals on the basis of 
 their images as visuelles, audiles, motiles, and 
 efforts have even been made to adapt a method 
 of teaching to the presumed " imagery tj^e " of 
 the student. In the present connection our in- 
 terest is only in inquiring whether and in what 
 degree " images of taste " are present. 
 
 Mental Images of Taste 
 
 Is there a " gustatory " or taste imagination 
 as well as a visual or an auditory imagination? 
 It should, of course, be borne in mind that tastes 
 may be " thought of," " referred to," or " indi- 
 cated" without there actually being taste qual- 
 
IMAGINATION AND MEMORY 147 
 
 ities present in experience. Thus, I may refer to 
 the " saltiness of the pork " and discuss it in 
 detail without having in consciousness the sensory 
 tang and quality of " salt." The saltiness may 
 be " represented " in my thinking in this case, not 
 by a taste quality at all, but by the word which 
 stands for such a quality, or even by a visual 
 picture of a white granular substance, or an elon- 
 gated strip of meat. Only if the immediate and 
 unanalyzable experience of sensory " salt " Is 
 present is there evidence, in this case, of an 
 " image of taste." 
 
 Obviously, we must mainly rely in such cases 
 on the testimony of the observer, although there 
 have been investigations made of a more objec- 
 tive sort, in which it is shown that the reported 
 " images " are so similar in character to actual 
 sense experiences that the observer, under appro- 
 priate conditions, cannot distinguish between the 
 two. 
 
 If we turn to the results of introspection or 
 individual testimony, we find that if taste images 
 exist at all they are at least reported as very much 
 less frequent and vivid than are images from 
 other senses. Thus, one observer, who in the 
 course of two years' observation of his own ex- 
 perience recorded 2,500 " images," classified 
 these as follows: 
 
148 THE SENSE OF TASTE 
 
 Vision , 57^ 
 
 Hearing , 20^ 
 
 Smell 6% 
 
 Taste 6% 
 
 Touch 4^ 
 
 Movement 3^ 
 
 Temperature 2$ 
 
 Organic 1% 
 
 Emotional 1% 
 
 Much the same state of affairs is revealed if 
 one attempts, when certain objects are named, to 
 record the imagery which the name evokes. In 
 response to the word " tornado " some indi- 
 viduals at once report visual appearances of fall- 
 ing houses and waving trees, while others report 
 auditory experiences of crashing buildings and 
 rushing wind. Within a few moments most ob- 
 servers report the appearance of images from 
 various senses, though some of them are more 
 vivid, more prompt, or more enduring than 
 others. In the case of taste, however, it is rare 
 that images are reported as either vivid, prompt, 
 or lasting. Usually when such an image is re- 
 ported at all it is described as lagging behind the 
 images of other modes, appearing to be dragged 
 in or reenforced by them, and to be transient, 
 weak, and fluctuating. It seems, also, that, 
 although images of taste are not easily aroused 
 directly by words, their appearance is facilitated 
 if a visual image or impression is present with 
 them. Consequently, when the poet or the adver- 
 tising writer desires to provoke imagined tastes 
 
IMAGINATION AND MEMORY 149 
 
 in his readers he often attempts to arouse them 
 more effectively by presenting suggestive pictures 
 of scenes associated with the object, or a tempt- 
 ing array of the articles themselves in an agree- 
 able setting. 
 
 Taste in Dreams and in Hallucinations 
 Reports of the sensory components of dream 
 experiences show taste to be an inconspicuous 
 factor in dream life. The following table shows 
 the results obtained by two independent investi- 
 gators when dreams of various individuals were 
 analyzed into the sensory elements reported: 
 
 Percentage of Occurrences 
 
 Sensory Mode 381 Dreams 300 Dreams 
 
 Vision 84.5^ t^% 
 
 Hearing 67.7^ ^% 
 
 Touch 10.8^ H 
 
 Smell 6.9^ 1% 
 
 Taste 6.35S 1% 
 
 Records of the hallucinations of sane and in- 
 sane people also show taste to play a relatively 
 minor role, so far, at least, as frequency of report 
 is concerned. In both cases visual, auditory, tac- 
 tile, and olfactory hallucinations seem to be more 
 common experiences. " Subjective tastes," or 
 tastes which do not appear to be caused by the 
 action of any substance in the mouth, are, how- 
 ever, by no means unknown, although in most 
 cases it is apparent that these tastes come from 
 some unsuspected irritation of the taste organs 
 by actual agents. Substances circulating in the 
 
I50 THE SENSE OF TASTE 
 
 blood may often be seen to be responsible for 
 these " subjective tastes." Thus, in diabetes the 
 excess of sugar in the blood may give rise to a 
 persistent sweet taste, and in case of jaundice 
 biliary products often produce sensations of bit- 
 ter. Various drugs, when present in the blood 
 stream, also provoke well-known effects in taste, 
 and it is quite probable that the taste hallucina- 
 tions associated with nervous and mental dis- 
 order have their origin in some abnormal irrita- 
 tion of the nerves or brain centers involved in 
 taste. Distilled water, which is presumably as 
 tasteless a substance as could be found, is re- 
 ported as tasteless by only about 50 per cent of ob- 
 servers. About 25 per cent report it as having a 
 bitter taste, while certain cases are found in which 
 it tastes sweet, or salt, or sour, or as having some 
 unknown taste. As the result of careful study of 
 these facts. Brown suggests that " we may perhaps 
 infer that the ' taste ' of water is not, after all, a 
 taste quality, but is due rather to the presence or 
 absence of some tactual characteristic; the absence, 
 perhaps, of the ' bite ' which is associated with 
 sweet, salt, and sour alike." It is also possible 
 that mechanical stimulation of the taste organs can 
 produce true taste qualities, just as mechanical 
 stimulation of the retina produces spots of light 
 and the tapping of a " warm spot " may produce 
 a faint sensation of warmth- 
 
CHAPTER XII 
 
 Unusual and Abnormal Taste Experiences 
 
 Gustatory Hallucinations and Aura 
 
 Disorders of taste are for the most part neither 
 as varied nor as bizarre as the abnormal condi- 
 tions of the more complex senses. Illusions of 
 taste, hallucinations, and subjective tastes we have 
 already referred to as frequently found. But of 
 them little can be said, except that they occur, and 
 that they present very little of psychological in- 
 terest. The appearance of these subjective tastes 
 may in some cases be due merely to the fact that 
 " a taste sensation easily associates itself with 
 certain muscular sensations. Thus, pressure on 
 the base of the tongue provokes the movements 
 of vomiting. With this muscular sensation may 
 be associated a sensation of bitter, which accom- 
 panies violent nausea." In ways similar to this 
 some observers would explain the reports of 
 others who find taste sensations to be produced 
 by mechanical stimulation of papillae. Most 
 observers do not get such results, and it may be 
 that these sensations when they are reported are 
 of the associated variety. 
 
 151 
 
152 THE SENSE OF TASTE 
 
 In the case of certain abnormal nervous con- 
 ditions, however, these features may assume 
 rather striking proportions. Thus, in the 
 " aurae," or preliminary symptoms preceding an 
 epileptic attack, the patient often experiences un- 
 pleasant bitter or metallic tastes, and distressing 
 feelings of numbness of tongue, etc. These sen- 
 sory manifestations are, however, by no means 
 as elaborate as are the " aurae " of some of the 
 dther senses, notably hearing and vision. 
 
 Partial and Complete Ageusia 
 
 Conditions of partial or complete ageusia, or 
 loss of taste, are well known. Such conditions 
 may result from the local application of various 
 drugs to the end organs, the paralyzing effect of 
 drugs on the nerve trunks, injury to, or operations 
 on, these nerves, or damage through injury, dis- 
 integration, or removal of special brain areas. 
 
 Taste Hallucinations of the Insane 
 
 In the case of the mentally deranged taste 
 hallucinations are usually disagreeable, and they 
 are often rationalized into a fabric of delusions, 
 — foul gases are said to be blown upon them, 
 poisons are being placed in their food. Such 
 patients behave in realistic manner, making vari- 
 ous defensive reactions, such as stuffing the nos- 
 trils with paper or cloth, spitting, and refusing 
 
TASTE EXPERIENCES 153 
 
 food. In some cases these hallucinations of the 
 insane obviously originate from local inflamma- 
 tion in the peripheral tissues, or from glandular 
 disturbances, and, hence, do not in themselves 
 constitute important pathological symptoms. In 
 some cases, however, such hallucinations arise 
 quite independently of such acute local conditions 
 of irritation, as in chronic psychic disorders or 
 dementias. Under such circumstances they have 
 greater significance, as they point to more deep- 
 seated mental and nervous disturbance. Just as 
 in normal life taste and smell are very closely 
 associated with each other, so, in these cases of 
 insane hallucinations, disorders of taste sensation 
 are likely to involve olfactory irregularities as 
 well. 
 
 Synasthesias of Taste 
 
 An interesting though apparently somewhat 
 rare phenomenon in the field of sensation is what 
 is known as " synaesthesia." By this is meant 
 cases in which a given sense quality arouses, or is 
 intimately associated with, qualities belonging to 
 other sensory modes. Thus, in the case of vision 
 and hearing, some individuals perceive the dif- 
 ferent vowel sounds, or the sound of musical in- 
 struments, as having color. One such person 
 reports that to him all the consonant sounds seem 
 to be very dark purple, while among the vowel 
 
154 THE SENSE OF TASTE 
 
 sounds " a " seems yellow, " e " is pale emerald, 
 and " u " is light dove color. 
 
 Taste, far from being an exception in this case, 
 is one of the senses in connection with which 
 " synaesthesias " must often occur. Salt, for in- 
 stance, is described by one observer as dull red, 
 bitter as brownish, sweet as clear bright red, and 
 sour as green or greenish-blue. To another ob- 
 server the taste of meats seems red or brown, the 
 taste of Graham bread is rich red in color, while 
 all ice creams (except chocolate and coffee) taste 
 blue. To still another reporter the sound of the 
 word " intelligence " tastes like fresh sliced toma- 
 toes, while the sound of the word " interest " 
 tastes like stewed tomatoes. There has been 
 much speculation as to the probable meaning and 
 mechanism of these synaesthetic experiences. In- 
 vestigation seems to show that the particular com- 
 binations are by no means universal, even among 
 those who report such observations, — ^they seem 
 to be individual and personal in their nature and 
 presumably in their origin. 
 
 It seems quite probable that in the main these 
 synaesthesias represent uncritical confusion of sen- 
 sory qualities with other sensory qualities, or with 
 the affective qualities, the feelings, which accom- 
 pany them. Thus, we often hear such phrases as 
 " bright taste," " heavy taste," " dark brown 
 taste," " green taste," " soft taste," " hard 
 
TASTE EXPERIENCES 155 
 
 taste," " smooth taste," etc. It is clear in most 
 of these cases that either a touch component is 
 included in the total taste experience (as in 
 "smooth taste," "soft taste," "hard taste"), 
 or that kinesthetic (muscular) factors are so in- 
 cluded (as in " heavy taste "), or that the phrase 
 is more or less designedly an analogy, or other 
 figure of speech (as in "sharp taste," "bright 
 taste," "clear taste"). The basis of such 
 analogies is sometimes rather easily discerned, 
 and often is seen to be the " feeling tone " which 
 the sensation arouses, — ^the effect or " affect " 
 which it produces. Thus, a heavy weight retards, 
 inhibits, and overpowers us. Some tastes have 
 this same overpowering affective tone, and may 
 be intelligibly described as " heavy." A clear, 
 bright day gives us recognizable feelings of pleas- 
 antness, relief, and gives to objects a distinctness 
 of contour. Some tastes, being well defined, 
 definitely localized, and highly agreeable and 
 soothing, may, then, be intelligibly described as 
 being " clear," " bright," or " pointed." These 
 illustrations represent, to be sure, only simple 
 forms of such synesthesias. But even the resem- 
 blance of the sound of " intelligence " to the taste 
 of fresh sliced tomatoes is by no means incompre- 
 hensible when we reflect that " freshness " means 
 " alertness," " sliced " suggests sharpness of 
 edge, while tomatoes thus prepared are usually 
 
156 THE SENSE OF TASTE 
 
 mature and ripe. For are not alertness, keen- 
 ness, and maturity the very marks of intelligence, 
 just as " dullness " and " greenness," also sense 
 qualities, are expressive of its absence ? In some- 
 what the same way we commonly speak of 
 " sweet odors," " sweet sounds of music," or 
 even sweet visual experiences, as in " a sweet 
 face." 
 
 A few individual cases of taste synaesthesia 
 have been studied in some detail. Such indi- 
 viduals are often shown to have a defective sense 
 of taste and to rely largely, in their recognition 
 of taste, on touch accompaniments, affective char- 
 acteristics, and such " color " experiences as the 
 various tastes are said to induce. 
 
 Perversions of Taste 
 
 Under certain unusual organic conditions, and 
 also still more commonly in the case of degen- 
 erate and neurotic individuals, various perver- 
 sions of taste occur. These perversions do not 
 seem to be exclusively gustatory in character, 
 since they involve more general factors, such as 
 appetite, craving, and emotional disturbance. 
 The name parorexia is sometimes given to these 
 perversions of taste and appetite. One of the 
 subforms, known as malacia, takes the form of 
 an urgent desire for hot spices, or for sour and 
 acid foods, such as pickles. What is known as 
 
TASTE EXPERIENCES 157 
 
 " salt hunger " is a very similar condition, espe- 
 cially often found among the lower animals. An- 
 other form of such perversion, known as pica, 
 shows itself in the desire to eat such substances 
 as clay, chalk, and similar gritty or earthy sub- 
 stances. Especially often among children and 
 aniong certain primitive peoples the chewing of 
 these substances often seems to give a satisfaction 
 quite unfamiliar to the majority of mankind. 
 Little is known about such perversions beyond the 
 fact that they have often been reported. 
 
 Under certain conditions of mental degeneracy 
 and nervous disorder perversions sometimes arise 
 which have been classed under the term allo- 
 triophagia. This perversion takes the form of 
 eating with apparent relish various kinds of filth 
 which are commonly offensive and disgusting. In 
 these cases It is quite possible that there is no 
 genuine taste disorder. Many, if, indeed, not 
 most, of our revulsions against substances known 
 as filth arise on the basis of associated circum- 
 stances, rather than on the simple basis of their 
 taste qualities. The falling away, or deteriora- 
 tion, of these associative and assthetlc controls in 
 the case of the demented and degenerate, and 
 their absence in the case of the feeble-minded and 
 imbecile, may easily lead to reactions which sug- 
 gest but do not necessarily involve genuine taste 
 disorder. 
 
CHAPTER XIII 
 Food and Flavor 
 
 The Biological Role of Taste 
 
 In considering the function of the sense of taste 
 it is common to dismiss the topic in a summary 
 manner by pointing out the fact, that in its original 
 primitive conditions, at least, this sense enables 
 the organism to discriminate between wholesome 
 and deleterious food. This function is, of course, 
 not to be neglected, especially if due credit be 
 given to the role played by smell in the same serv- 
 ice. It is however true that, although the indi- 
 cations of taste and smell may be, for lower forms 
 of animal life, fairly trustworthy guides in the 
 selection of edible substances, such criteria as 
 taste and odor can by no means be relied on by 
 human beings. In a general way it is, of course, 
 true that wholesome substances possess taste qual- 
 ities which are agreeable and enjoyable, while 
 foul, decaying and poisonous substances are often 
 characterized by tastes and odors that arouse in 
 us disgust and revulsion. 
 
 158 
 
FOOD AND FLAVOR 159 
 
 But in the complex lives of human beings, at 
 least, this sort of natural adaptation is far from 
 adequate to constitute a dietetic guide. Not only 
 is it true that many substances accessible to human 
 beings are injurious and unwholesome, in spite 
 of their agreeable taste; it is equally true that 
 many substances that are initially distasteful may 
 be either nourishing or remedial. Human beings 
 find it necessary to supplement, or even to sup- 
 plant, the " beneficent guardianship " of taste by 
 the introduction of various other sources of infor- 
 mation and criteria of selection. 
 
 We do not find, however, that the sense of taste 
 shows any evidence of deterioration as the result 
 of such loss of function. Probably never before 
 in the history of our race has there been such 
 diligence and zeal in ministering to the demands 
 and satisfactions of our appetite. In the prep- 
 aration, marketing, and serving of food the ap- 
 peal through tastefulness and flavor stands second 
 only to that through purity and cleanliness. The 
 situation is neatly stated by Jane Addams in the 
 following words : " Perhaps the neighborhood 
 estimate (of their New England kitchen) was 
 summed up by the woman who frankly confessed 
 that the food was certainly nutritious, but that 
 she didn't like to eat what was nutritious ; that she 
 liked to eat ' what she'd ruther.' " 
 
 It is clear at once that the satisfactions of taste 
 
i6o THE SENSE OF TASTE 
 
 are pursued, either secretly or openly, for their 
 own sake, and often in obvious disregard of their 
 dietetic consequences. Shall we dismiss this pur- 
 suit as only an instance of the search for pleasure 
 in its own right or wrong, or is there to be dis- 
 cerned a further function of taste experiences 
 quite aside from their guidance to eating, their 
 warning of danger, and their immediate sensory 
 pleasure ? 
 
 Taste and Digestion 
 
 Recent studies of the role of taste in the 
 economy of the organism show very decidedly 
 that such an additional function, and a very im- 
 portant one,, must be recognized. These investi- 
 gations have revealed the fact that the pleasur- 
 able taste of food (along with its agreeable odor 
 and appearance) is responsible for the initiation 
 of the first stages of the process of digestion. 
 Further, they have shown that disagreeable tastes 
 and odors ( along with pain, fear, and other emo- 
 tional excitement) may effectually retard or even 
 completely inhibit these very important processes. 
 Not only does the mouth " water " at the smell, 
 or sight, or thought, of delicious morsels, but the 
 stomach itself responds, in an anticipatory fash- 
 ion, to the taste of agreeable substances placed in 
 the mouth. That " good digestion waits on ap- 
 
FOOD AND FLAVOR i6i 
 
 petite " is a physiological fact, as well as an 
 ancient proverb. 
 
 In the middle of the last century two observers 
 in Leipsic reported the pouring out of gastric 
 juice at the mere sight or smell of a favorite food 
 in the case of " a hungry dog which had a fistulous 
 opening through the body wall into the stomach." 
 More recently it has been experimentally shown 
 that similar flow of gastric juice follows upon the 
 tasting of agreeable food, even if the food itself 
 is not allowed to reach the stomach. So relevant 
 are these findings to the point we are now con- 
 sidering that the following summary, by Cannon, 
 of the work of Pavlow may well be quoted in 
 detail : 
 
 Experimental Evidences 
 
 " The feelings or affective states favorable to 
 the digestive functions have been studied fruit- 
 fully by Pavlow, of Petrograd, through ingenious 
 experiments on dogs. By the use of careful sur- 
 gical methods he was able to make a side pouch 
 of a part of the stomach, the cavity of which was 
 wholly separate from the main cavity in which 
 the food was received. This pouch was supplied 
 in a normal manner with nerves and blood vessels, 
 and, as it opened to the surface of the body, the 
 ^rnount and character of the gastric juice s§?ret?d 
 
1 62 THE SENSE OF TASTE 
 
 by it under various conditions could be accurately 
 determined. Secretion by that part of the stomach 
 wall which was included in the pouch was repre- 
 sentative of the secreting activities of the entire 
 stomach. The arrangement was particularly ad- 
 vantageous in providing the gastric juice unmixed 
 with food. In some of the animals thus operated 
 upon an opening was also made in the esophagus, 
 so that when the food was swallowed it did not 
 pass to the stomach, but dropped out on the way. 
 All the pleasures of eating were thus experienced, 
 and there was no necessity of stopping because of 
 a sense of fullness. This process was called 
 ' sham feeding.' The well-being of these animals 
 was carefully attended to; they lived the normal 
 life of dogs, and in the course of months and 
 years became the pets of the laboratory. 
 
 Pavlow showed that the chewing and swallow- 
 ing of food which the dogs relished resulted, after 
 a delay of about five minutes, in a flow of natural 
 gastric juice from the side pouch of the stomach 
 — a flow which persisted as long as the dog 
 chewed and swallowed the food and continued 
 for some time after eating ceased. Evidently the 
 presence of food In the stomach Is not a prime 
 condition for gastric secretions, and, since the 
 flow occurred only when the dogs had an appetite 
 and the material presented to them was agree- 
 
FOOD AND FLAVOR 163 
 
 able, the conclusion was justified that this was a 
 true psychic secretion." 
 
 In several cases necessary operations on human 
 beings have permitted of observations similar to 
 these experiments on dogs. Thus, Richet, who 
 had opportunity to observe such a case, " re- 
 ported that whenever the girl chewed or tasted 
 a highly sapid substance, such as sugar or lemon 
 juice, while the stomach was empty, there flowed 
 from the fistula a considerable quantity of gastric 
 juice." Another observer, Hornborg, " found 
 that when the little boy whom he studied chewed 
 agreeable food a more or less active secretion of 
 gastric juice invariably started, whereas the chew- 
 ing of an indifferent substance, as gutta-percha, 
 was followed by no secretion." 
 
 Carlson has reported numerous similar obser- 
 vations on an adult. In the case of this man the 
 sight, smell, or thought of food, even when he 
 was hungry, was inadequate to cause the gastric 
 juice to flow. Moreover, " the mere act of chew- 
 ing indifferent substances, and the stimulation of 
 the nerve endings in the mouth by substances 
 other than those related to food," caused no 
 secretion. But a few minutes after the taste 
 organs were stimulated by edible substances it 
 was seen that not only did the flow of gastric juice 
 begin, but the " hunger contractions " of the 
 stomach were inhibited. Further, the secretion of 
 
i64 THE SENSE OF TASTE 
 
 gastric juice in this patient was clearly seen to 
 vary with the palatability of the food. The 
 chewing of bread and butter yielded a smaller 
 flow than did the mastication of meat, and the 
 flow was always greatest during the chewing of 
 desserts, or on occasions when the food was said 
 to be " unusually fine." Oranges, of which the 
 patient was especially fond, produced a greater 
 flow than did pies, puddings, and other fruits. 
 Carlson, in reporting these observations, says: 
 " There is no question but that the mastication 
 of a palatable dessert at the end of a meal serves 
 to augment and prolong the appetite secretion of 
 the gastric juice." 
 
 In referring to such cases Cannon has con- 
 cluded : " All these observations clearly demon- 
 strate that the normal flow of the first digestive 
 fluids, the saliva and the gastric juice, is favored 
 by the pleasurable feelings which accompany the 
 taste and smell of food during mastication, or 
 which are roused in anticipation of eating when 
 choice morsels are seen or smelled. These facts 
 are of fundamental importance in the serving of 
 food, especially when, through illness, the appe- 
 tite is fickle. The degree of daintiness with which 
 nourishment is served, the little attentions to 
 aesthetic details — the arrangement of the dishes, 
 the small portions of food, the flower beside the 
 plate — all may help to render food pleasing to 
 
FOOD AND FLAVOR 165 
 
 the eye and savory to the nostrils, and may be the 
 deciding factors in determining whether the 
 restoration of strength is to begin or not." 
 
 The Function of Taste in the Organic Economy 
 
 The preliminary nature of these anticipatory 
 secretions of the digestive juices is by no means an 
 adequate measure of their ultimate importance. 
 Studies of the mechanism of digestion show that 
 each stage, as it occurs, either directly or indi- 
 rectly, through its product, affords the appro- 
 priate stimulus which evokes the following stage. 
 Thus, continued flow of gastric jiiice is provided 
 for by the action of the preliminary flow or its 
 products on the walls of the stomach; and other 
 juices, such as the bile and the pancreatic, are in 
 turn released by the action of this continued flow. 
 
 The pleasurable sensations of taste are thus 
 the initial stimulus to the whole series of diges- 
 tive processes. Even in the absence of hunger 
 these sensations seem potent to initiate the diges- 
 tive mechanism. Among the most interesting of 
 recent physiological studies are those showing the 
 very great sensitivity of the important organic 
 mechanisms, especially those of secretion, to such 
 experiences as shock, worry, fear, anger, grief, 
 excitement, and pain. All these factors tend to 
 retard the activity of the digestive system, while 
 
i66 THE SENSE OF TASTE 
 
 they may also be seen to reenforce the activity 
 of other mechanisms. As opposed to the effect of 
 these factors, pleasurable experiences connected 
 with food serve not only to guide the organism 
 in its choice, but play an important part in its 
 effective appropriation and assimilation, through 
 their action in setting the digestive mechanisms 
 in action, and in guaranteeing the continuation of 
 this action after the completion of the act of 
 eating. 
 
 Music and dancfe, jest and general merriment, 
 genial conversation and cordial friendship, pros- 
 perity and individual success, fragrance, color, 
 bodily ease, and a clear conscience — these and all 
 the other joys of life play their part in promoting 
 the bodily welfare of the organism. Conspicu- 
 ous and potent among these favoring influences 
 are the sensations of taste and the strongly toned 
 feelings with which they are so closely associated 
 — ■" the satisfactions of the palate." Even the 
 various " bitters " which are so commonly used 
 as " appetizers " seem to owe such efficacy as 
 they may possess to the influence of their taste 
 on the preliminary flow of " appetite gastric." 
 Carlson has shown that these bitters, introduced 
 directly into the stomach in medicinal doses, have 
 no influence on the hunger mechanisms. In larger 
 doses their effect is inhibition of hunger. Acting 
 in the mouth, they also retard the hunger con- 
 
FOOD AND FLAVOR 167 
 
 tractions of the stomach in proportion to their 
 intensity as taste stimuli. In so far, then, as " bit- 
 ters " are " appetizing," it Is by virtue of their 
 taste qualities, rather than their medicinal prop- 
 erties, and the act of swallowing them would seem 
 to be superfluous. 
 
CHAPTER XIV 
 
 The iEsTHETic Value of Taste 
 
 The Higher and Lower Senses 
 
 When people are asked to state which are the 
 higher and which the lower senses they feel no 
 hesitation in deciding. When asked to arrange 
 the various senses in an order of merit on this 
 basis they are able to do so promptly. More- 
 over, their various arrangements agree very 
 closely with each other. Vision commonly stands 
 at the top of the series; then hearing; touch and 
 smell are given third and fourth places about 
 equally often; taste is likely to be next; and finally 
 temperature, sensations of movement, and the 
 more general organic sensations. When asked to 
 state what meaning they give to the term 
 " higher " in making this arrangement there is 
 more disagreement in the nature of the replies. 
 Occasionally an individual asserts that by 
 " higher " he means more elaborate, complicated, 
 — " highly " differentiated. A few individuals 
 mean by " higher " more useful, indispensable, — 
 " higher " in value. But by far the larger num- 
 
 i£8 
 
^ESTHETIC VALUE OF TASTE 169 
 
 ber of individuals mean neither the one nor the 
 other of these two notions, but have In mind some 
 characteristic which is not immediately related 
 either to structural complexity, genetic antiquity, 
 nor practical utility, — a characteristic which can 
 only be described as ethical or aesthetic. 
 
 Evidence of a cleavage of the senses on an 
 ethical basis is abundant. Quotations from Bur- 
 ton's " Anatomy of Melancholy " may serve as 
 representative of statements that can easily be 
 found in the writings of all centuries, from the 
 Socratic period, through the reflections of the 
 schoolmen, down to the modern textbooks of 
 psychology. Says Burton: 
 
 " Of these five senses sight Is held to be most 
 precious and the best. . . . Hearing is a 
 most excellent outward sense. . . . Taste is 
 a necessary sense. . . . Touch, the last and 
 most Ignoble of the senses, yet of as great neces- 
 sity as the others, and of as much pleasure." 
 
 Contemporary phraseology and convention are 
 just as eloquent in the matter. There is common 
 agreement that some of the senses, in their exer- 
 cise or consequences, are ennobling, dignified, 
 pure, and worthy; others, either In their exercise 
 or consequences, are felt to be degrading, de- 
 basing, vile, and Iniquitous. An individual who 
 revels in impressions of sight and sound, and in- 
 dulges to the utmost the raptures afforded by the 
 
I70 THE SENSE OF TASTE 
 
 tones, melodies, concords, the colors and their 
 harmonies, and the elements of form, design, and 
 arrangement, we are likely to find classified by his 
 associates as " sensitive," " temperamental," " ar- 
 tistic." But one who revels to the same or even 
 much less degree in the unholy impressions of 
 contact, temperature, smell, and taste is held to 
 be " sensuous " rather than " sensitive," " glut- 
 tonous " rather than " temperamental," and 
 " vicious " rather than " artistic." The former 
 pleasures minister to a " divine fire," the latter 
 only to " lust " and " appetite." 
 
 Similarly, we esteem in quite distinctive man- 
 ner the workman whose craft consists in the 
 preparation and arrangement of sights and 
 sounds in pleasing elements, orders, and composi- 
 tions. He is held to have " acquired merit," 
 however unsuccessful his labors, and receives 
 warm social approbation. He is an " artist." 
 But the workman whose craft consists in the prep- 
 aration and presentation of acceptable sensations 
 of taste, smell, touch, and temperature, what of 
 him? He is neither held to have "acquired 
 merit " nor to deserve any enviable amount of 
 social recognition. He is only a " cook," a 
 " chef," or, at the most, a " chemist " or a 
 " dietitian." Only in the comic supplements is 
 he ever an " artist." Painting, for instance, is 
 held to be an " art " ; but cooking is only a " serv- 
 
ESTHETIC VALUE OF TASTE 171 
 
 ice." The one is rewarded by distinction and 
 eminence, the other, when rewarded at all, by 
 wages. 
 
 In the field of aesthetics the distinction between 
 the " higher " and the " lower " senses is no less 
 clear. Museums and galleries we have in abun- 
 dance in which are preserved and displayed the 
 treasures of light and shade, color and form, line 
 and arrangement. Private and public funds are 
 appropriated in order that these impressions may 
 have the widest possible circulation. Visitors and 
 classes throng the corridors o,f these storehouses ; 
 teachers and schools flourish on the profits de- 
 rived from the communication and publication of 
 the principles concerned in their manufacture; 
 statues are erected to the most deserving crafts- 
 men; and earnest apprentices starve in foreign 
 garrets in order that their handicraft may in time 
 adorn these walls. Much the same thing is true 
 of pleasing arrangements of sound impressions. 
 All possible pains are taken to record the scheme 
 and plan of their production, and the heartiest 
 welcome is accorded any device, instrument, or 
 organization which will facilitate their being 
 stored up and poured out again for the delecta- 
 tion of remote or future audiences. 
 
 But to what museum or gallery shall one go 
 who longs to experience the glorious array of 
 pleasing contacts, textures and pressures, odors. 
 
172 THE SENSE OF TASTE 
 
 tastes, and temperatures? Where shall one find 
 stored up representatives of the most satisfying 
 and thrilling touch impressions that experience 
 has ever yielded, the whole gamut of delectable 
 odors, with all the offensive ones left out; all the 
 aromas and savors and flavors in which the gus- 
 tatory and olfactory world is so rich? And all 
 the organic thrills, the kinaesthetic whirls and 
 starts, and the delicious dizzinesses of static ex- 
 periences? Coney Island and its brood are the 
 only institutions that even pretend to minister to 
 those whose nature yearns for these satisfactions, 
 and Coney Island is supported neither by phil- 
 anthropic endowment nor by public appropria- 
 tions. It is even said that its joys are thought to be 
 " vulgar " among certain classes of people, whose 
 passions run mainly toward sights and sounds. 
 
 There can be no doubt about it. Certain of 
 the senses are more jesthetlc than others, if by 
 this we mean that special arts have been built up 
 which busy themselves with the materials afforded 
 by them. Certain of the senses, again, are un- 
 ffisthetlc, in the sense that the materials afforded 
 by them have not yielded to that sort of structural 
 manipulation which constitutes the procedure of 
 one of the " fine arts." And, furthermore, such 
 manipulation as they do submit to is not only not 
 considered " fine," but is designated by the nega- 
 tive term " unsesthetic " ; the materials them- 
 
ESTHETIC VALUE OF TASTE 173 
 
 selves, as well as those who busy themselves with 
 them, are quite likely to be esteemed " coarse " 
 and " nasty." 
 
 Bounty of Nature and Ecclesiastical Censorship 
 
 One may well inquire into the reasons for such 
 a curious state of affairs. Does it merely signify 
 that agreeable sights and sounds are so rare in 
 nature that special social encouragement has come 
 to be given for their production, while pleasing 
 contacts, pressures, tastes, smells, etc., are so 
 abundantly provided in the natural course of ex- 
 perience that no such sanction is called for ? Even 
 if this were true, does it follow that the sanction 
 of the one group need necessarily involve the 
 taboo of the other? Does it perhaps merely in- 
 dicate that early in the history of art the Church 
 and its leaders learned that the original tendency 
 of men and women to indulge themselves In the 
 voluptuous impressions of certain of the senses 
 was so strong that the immediate joys of earth 
 promised to outweigh the promised blessings of 
 heaven? Such a discovery might well have re- 
 sulted in an authoritative denunciation of these 
 types of experience and in an artificial exaltation 
 of the tamer and milder senses, whose objects 
 could be perceived at a remote distance and by 
 many observers, and could be, therefore, more 
 minutely scrutinized by the ecclesiastic censors. 
 
174 THE SENSE OF TASTE 
 
 Or does it perhaps mean that some of these sense 
 impressions from their very nature are either un- 
 suitable as materials for that sort of manipulation 
 and craftsmanship which we call artistic, or, from 
 their very nature or consequences, are inimical 
 to and destructive of those endeavors which we 
 have come, on other grounds, to conceive to be 
 the most worthy and valuable tendencies of men 
 and women? The bounty of nature and the 
 ecclesiastical censorship we may dismiss from the 
 present consideration, however worthy they may 
 be of reflection, and confine our present inquiry to 
 the question of whether or not the impressions 
 afforded by some of the senses, such as taste, for 
 example, are, by their very nature, inadequate 
 as raw materials of aesthetic manipulation and 
 artistic creation. 
 
 The Psychophysical Attributes 
 
 It may be well to begin our inquiry with a con- 
 sideration of certain of the technical psychological 
 characteristics and properties of the different 
 senses, properties which can be measured and ex- 
 pressed in quantitative terms. We may then 
 observe whether their order, when arranged on 
 these bases, shows any correspondence to their 
 order in the scale of assthetic value, and where, 
 in such a scale, the sense of taste belongs. The 
 following table brings together the facts concern- 
 
^ESTHETIC VALUE OF TASTE 175 
 
 *M O 
 
 o 
 
 os.s 
 
 5« 
 
 u 
 <u 
 ta 
 
 O 
 
 CO 
 
 q 
 o 
 
 
 |2 
 
 a 5 
 > 
 
 •d 
 a 
 
 t3 
 
 S <o 
 -.9 
 
 sfliJ 
 0^ 
 
 a 
 
 o 
 n 
 
 M 
 
 a 
 
 •d 
 
 Sg 
 
 goj 
 
 
 d t5 S 
 
 u Ha 
 " ""PS 
 
 g« 
 
 in o 
 en iJ 
 
 O <U 
 
 O-d 
 
 - ° 
 
 o 00 
 
 d 
 o 
 
 ^ >S 
 
 ■s 
 
 o2 
 
 n o 
 
 ifl to 
 
 COS 
 
 o 
 o 
 
 a 
 
 u 
 
 <u 
 
 o 
 Q 
 
 S O 
 
 u 
 
 is 
 
 •2S 
 
 CO «J 
 
 > 
 
 a 
 o 
 
 8 " 
 
 3.S 
 
 4> m 
 
 VI 
 2 3 01 
 
 m " J) 
 
 fa ±! •" 
 
 o t*. 
 
 IH fe " 
 
 v 
 
 •"3 2 
 ] -a 
 
 ) ll 4-> 
 
 c tn 
 
 V V iu 
 
 g-dl 
 
 ■dig 
 ■d 
 
 
 
 65 
 
 •a 
 
 bo 
 'u S 
 
 CO n V? 
 
 
 2 « " 
 ■*j 2 © 
 2 a - 
 
 a> 
 
176 THE SENSE OF TASTE 
 
 ing four of these characteristics. In the first 
 column the senses are arranged in the commonly 
 accepted order of assthetic value, and the degree 
 of correspondence can be easily made out by 
 comparing this column with those in which the 
 various other properties are indicated. 
 
 It requires only a glance at this table to reveal 
 the fact that we possess much more definite 
 knowledge about sight and hearing in these re- 
 spects than we do about the other modes of sen- 
 sation. In the case of these two senses, the four 
 characteristics indicated in the table can be stated 
 with considerable precision and certainty. But 
 in the case of the other senses, and of taste in 
 particular, only broad and vague statements can 
 be made, for the most part. Even the number of 
 discriminable qualities which these senses afford 
 is unknown, and statements concerning the other 
 properties are mainly confessions of difficulty or 
 ignorance. It is difficult to judge to what degree 
 this state of affairs is due simply to the greater 
 attention that has been given to sight and hearing 
 in precise psychological investigation, and to what 
 degree it is due to difficulties inherent in the nature 
 of the sense impressions afforded by the other 
 modes. Nevertheless, it is apparent that no one 
 of the special characteristics indicated in the table 
 can be held responsible for the sharp cleavage 
 commonly made between the worthy and the 
 
^ESTHETIC VALUE OF TASTE 177^ 
 
 ignoble senses. Consideration of the character- 
 istics in detail shows that we must look elsewhere 
 for the reasons why the lower senses are unaes- 
 thetic, and even, perhaps, for the reasons why 
 they are lower. 
 
 With respect to number of discriminable qual- 
 ities, for instance, sight and hearing, with their 
 many thousand distinguishable degrees of impres- 
 sion, might seem to afford such an abundance of 
 raw material that this alone would explain why 
 the principal fine arts have come to be based on 
 these senses. But it must be pointed out that this 
 enumeration of qualities has reference only to the 
 definitely identifiable, classifiable, and control- 
 lable degrees of impression. The mere fact that 
 odors can be classified under only nine headings, 
 to which general terms can be given, does not at 
 all mean that there are but nine distinguishable 
 smells. Almost every different object in the world 
 has its own characteristic odor. We have not 
 developed abstract names for these odors, to be 
 sure. We are usually content to designate the 
 odor by the name of the object with which it is 
 associated. And when one bears in mind the mul- 
 titudinous variations of these odors, their differ- 
 ent intensities, mixtures, and modifications, one is 
 inclined to believe that it is only the infinite variety 
 of smell experiences that prevents our enumerat- 
 ing, classifying, and designating them. And what 
 
178 THE SENSE OF TASTE 
 
 has just been said of smell is equally true of touch, 
 taste, and organic sensations. It is also true that 
 the separate lower senses are seldom stimulated 
 independently, — thus taste is always accompanied 
 by smell, touch, temperature, etc. May it per- 
 haps be true that the very fact that these impres- 
 sions cannot be estimated, isolated, and repro- 
 duced at will has something to do with their in- 
 ferior assthetic value? However this may be, it 
 is clear that the mere variety of impressions 
 aifforded is not the criterion of which we are in 
 search. 
 
 One might be tempted to suppose that the 
 sharpness of discrimination of the various senses, 
 the keenness with which differences in the strength 
 and intensity of impressions can be detected, 
 might be an important factor in determining their 
 availability for esthetic manipulation. The fig- 
 ures given in the table under this heading indicate 
 the proportion that must be added to a stimulus 
 in order to make it just perceptibly more intense. 
 The temptation is removed at once by a mere 
 inspection of the values. Sight is, to be sure, the 
 most delicate of the senses in this respect, as it is 
 also in number of isolable qualities. But kines- 
 thetic sensation follows close upon it, while smell 
 stands third in the list, and hearing is no more 
 sensitive than pressure. In the case of taste and 
 the other senses th^ values are unknown or difE- 
 
.ESTHETIC VALUE OF TASTE 179 
 
 cult to determine, but it is clear that the aesthetic 
 values of the different senses do not depend 
 merely on their various psychophysical constants. 
 The quickness with which one can react to or 
 perceive impressions from the various senses dis- 
 closes much the same state of affairs. Basing our 
 comparison on the average reaction times to the 
 most commonly available impressions and inten- 
 sities in each case, hearing, touch, and tempera- 
 ture are seen to be about equally prompt, while 
 sight stands fourth on the list. With respect to 
 the period of time through which a sensation con- 
 tinues to persist, the so-called " life span " of an 
 impression, only three of the values, those for 
 sight, hearing, and touch, have been determined, 
 and these bear no significant relations to each 
 other. But these times are all very short, and 
 the corresponding modes of sensation stand high 
 in the jesthetic scale. The other values, although 
 not determined, are known to be much longer 
 than these. Is it possible that the sluggishness of 
 these senses and the persistence of impressions 
 once set up through them is so great that the im- 
 pressions do not submit to the forms, patterns, 
 and structures which constitute artistic treatment ? 
 Or may it not be equally true that the fugitive 
 character of impressions from the higher senses 
 is what has made necessary the development of 
 treatment by means of pattern and structure ? 
 
i8o THE SENSE OF TASTE 
 
 The Tendency to Adaptation 
 
 Suggested by this question of " life span " of 
 sensations is another characteristic which one 
 might expect to find important, — ^viz., what we 
 have in an early chapter referred to as the " ten- 
 dency to adaptation " of the different senses. In 
 the case of odors, temperatures, and contacts, we 
 easily and speedily become adapted to continuous 
 presence of impressions and cease to be aware of 
 their existence. Thus, we soon become adapted 
 to the presence of hats on our heads, the clothes 
 on our backs, the smell of smoke, and even to such 
 extreme temperatures as that of the stoking room. 
 Continuous stimulation of one of these senses so 
 raises the threshold of the sense organ that the 
 original stimulus ceases to be effective. So far 
 as practical and ffisthetic purposes are concerned, 
 we are then fatigued to the particular impression. 
 We may be gratified to find that this tendency to 
 adaptation is not nearly so conspicuous in the case 
 of sight. But we will be equally dismayed to 
 learn that the tendency is as prominent in the case 
 of hearing as it is iii the so-called, lower senses. 
 Moreover, this tendency refers to continued 
 stimulation of the same degree or quality, 
 whereas in aesthetic manipulation the qualities 
 presented are varied from moment to moment 
 and from point to point. 
 
^ESTHETIC VALUE OF TASTE i8i 
 
 Spatial Attributes of Taste Qualities 
 
 On the whole, then, these strictly psychological 
 or psychophysical comparisons are so unsatisfac- 
 tory that we are compelled to look elsewhere for 
 the criteria of the raw material of aesthetics. 
 Some writers have suggested that the absence of 
 -definite and formal spatial attributes and systems 
 is what makes certain of the senses unsuitable for 
 aesthetic treatment. But there are two important 
 objections to this suggestion. One is our earlier 
 question as to the reasons why aesthetic treatment 
 should necessarily consist of arrangement in 
 spatial and temporal series and patterns. Unless 
 some excellent reason to the contrary is given, we 
 are free to assume that this is not a necessity, but 
 merely an incidental result, following from the 
 character of the materials, which, for other rea- 
 sons, for which we seek, are chosen as the raw 
 materials for aesthetic treatment. The other ob- 
 jection, which is, perhaps, more convincing, is the 
 fact that, whereas touch and kinaesthetic impres- 
 sions both possess immediate voluminousness and 
 take their place readily in a spatial manifold of 
 position, direction, distance, and form, they do 
 not yield to aesthetic treatment; while sound and 
 taste, one of which easily ranks second and the 
 other of which belongs low down in our aesthetic 
 scale, possess extent in only a very doubtful and 
 
1 82 THE SENSE OF TASTE 
 
 probably analogical manner, and are almost, if 
 not wholly, lacking in those qualities which would 
 enable them to participate in a manifold of posi- 
 tion, direction, distance, and form. As for tem- 
 poral attributes, such as duration and sequence, 
 all impressions possess them, from whatever 
 sense they originate. The idea that the difficulty 
 or impossibility of giving spatial and temporal 
 form to the lower sensations prevents the repre- 
 sentation of nature by means of them, and that 
 this is a sufficient reason for regarding them as 
 inferior is anything but adequate. 
 
 Immediate Affective Value of Taste 
 
 Perhaps the greatest surprise comes when we 
 consider the immediate affective value of impres- 
 sions from the different senses. Impressions of 
 taste, smell, and contact bear with them or imme- 
 diately provoke very definite and powerful feel- 
 ings, — feelings of pleasantness and disagreeable- 
 ness, excitement and calm, tension and relief. 
 Still more complex emotions than these simple 
 feelings are called up more easily and universally 
 by impressions from these senses than in any 
 other way. Their immediate pleasure tone and 
 their associated emotions may be, and usually are, 
 exceedingly rich and intense. The smell of new- 
 mown hay, coffee, flowers, whiffs of the salt sea 
 breeze, the odors of animals, foods, spices, and 
 
^ESTHETIC VALUE OF TASTE 183 
 
 herbs move us to strong emotions. The stroking 
 of fur, the cool of evening, the dehcious languor 
 of a sun bath — all these have high and immediate 
 affective value that can hardly be exceeded by any 
 emotions provoked by colors, forms, noises, and 
 tones. In general, those senses that are closely 
 connected with our personal and bodily welfare, 
 as is the case with taste, provoke strong affective 
 reactions and convey to us a strong sense of 
 reality. Those senses which are much less inti- 
 mately related to our immediate bodily welfare 
 possess much weaker feeling tone and provoke 
 much less emphatic emotional reactions. Dis- 
 agreeable odors, tastes, and contacts are quite 
 beyond our endurance, but few are the sights and 
 sounds to which we cannot easily reconcile our- 
 selves. Here, then, we have the interesting and 
 perhaps unexpected fact that the sense impres- 
 sions possess aesthetic value just to the degree that 
 they fail to arouse in us definite and powerful 
 feelings. The inverted arrangement on the basis 
 of aesthetic value gives us precisely the order on 
 the basis of immediate affective value. Santa- 
 yana's assertion that the small range and variety 
 of pleasure-toned qualities among the lower 
 senses explains their non-aesthetic character, in 
 part, is seen to be not only inadequate, but even 
 a perversion of the facts. Just in that degree to 
 which sense impressions fail to produce in us 
 
1 84 THE SENSE OF TASTE 
 
 immediate pleasures and aversions, fail to pro- 
 voke us to instinctive emotions of joy and disgust, 
 fail to stir in us moods of irritation and acquies- 
 cence, — in just that degree do they declare them- 
 selves to be adequate raw materials for the fine 
 arts. If, as we are often told, the primary pur- 
 pose of art is to please, this must be an entirely 
 unexpected state of affairs, and the low position 
 of taste in the aesthetic scale becomes quite unin- 
 telligible. 
 
 Development in the Individual and the Race 
 
 Perhaps this is as appropriate a place as any 
 in which to point out that the order of the senses, 
 on the basis of their asthetic value, is approxi- 
 mately that of their philogenetic and ontogenetic 
 development. The simplest and most undiffer- 
 entiated forms of animal life possess, in more or 
 less rudimentary form, sensitivity to impressions 
 which must resemble closely what we know as 
 contact, pressure, movement, and temperature. 
 Touch, as Aristotle tells us, is the " mother 
 sense." Starting from this form of sensibility as 
 a basis, the other senses develop as we ascend 
 the animal series, by processes of increasing com- 
 plexity and refinement. Taste and smell, as we 
 know those experiences", were probably the next 
 to differentiate themselves from the vague mass 
 
^ESTHETIC VALUE OF TASTE 185 
 
 of tactual and organic sensation, then hearing, 
 and last of all sight. And there is evidence of 
 sequence within a single sense; thus it would ap- 
 pear that brightness vision, sensibility to mere 
 light and shadow, antedated color vision by a 
 considerable interval, and even that sensibilities 
 to the various color impressions developed in 
 some sort of serial order. It is also true that the 
 sense organs upon which fall the stimulations of 
 the physical world are, at the birth of the indi- 
 vidual, in very diverse conditions of functional 
 perfection. The nerves which underlie sensations 
 of taste, touch, temperature, and pain operate 
 perfectly at birth. Hearing is defective for one 
 to two weeks after birth, and the mechanism of 
 vision is still more imperfect and commonly re- 
 mains so for several weeks. From the point of 
 view of the three meanings of the word " higher," 
 the ethical, the aesthetic, and the genetic, the order 
 of the senses is the same. Such close agreement 
 cannot be entirely without significance. 
 
 J The Imaginative Value of Taste 
 
 A further characteristic which correlates closely 
 with the aesthetic arrangement is to be found in 
 the relative ease with which images can be called 
 up and contemplated in the various modes of sen- 
 sation, in the absence of any physical stimulation, 
 — ^what we may call the imaginative possibilities of 
 
1 86 THE SENSE OF TASTE 
 
 the different senses. With most people visual and 
 auditory imagery is both more vivid and intense, 
 and more facile and prompt, than is imagery 
 within any of the other sensory modes. We have 
 in another section referred to one observer who 
 recorded his mental images as they occurred or 
 were noticed until 2,500 had been enumerated, 
 and who reports that 57 per cent of them were 
 visual, 29 per cent auditory, leaving only a total 
 of 14 per cent for images from all the other 
 senses. Dreams, which consist mainly of im- 
 agery experiences, are commonly visual in char- 
 acter, with hearing a close second, and the 
 other modes hardly represented at all. Hal- 
 lucinations reported by supposedly normal people 
 are in 90 per cent of the cases either visual 
 or auditory, and the visual are about twice as 
 frequently reported as the auditory. Records of 
 hallucinations among the insane show vision and 
 hearing clearly most prominent, with hearing 
 somewhat more prominent than sight. Can it be 
 that the possibility of recall in the form of 
 imagery, contemplation in the absence of the 
 original stimulus or object, is one of the prime 
 qualifications of sensory impressions that are to 
 serve as aesthetic material? There will probably 
 be no exception taken to such a generalization on 
 the part of anybody. The order on the basis of 
 imaginative value is identical with that on the 
 
ESTHETIC VALUE OF TASTE 187 
 
 basis of aesthetic value, ethical value, and genetic 
 development. 
 
 The Non-Social Character of the Lower Senses 
 
 It is interesting to note that the higher senses 
 are also the so-called distance receptors; they do 
 not require immediate contact with the stimulus- 
 producing object, whereas the lower senses in- 
 form us mainly concerning objects that are in 
 direct or approximate contact with our own body. 
 By virtue of this fact, as has often been remarked, 
 it is possible for many of us to see the same ob- 
 ject, such as a rainbow, however far apart we 
 may be from each other. And we can all hear 
 the same melody-producing instrument if we place 
 ourselves within a certain fairly large area. But 
 social experience is scarcely possible in the case 
 of contact, taste, smell, temperature. Here the 
 most we can do is to get the experiences in succes- 
 sion, and even this is often impossible. Even 
 when it is possible to get the experiences in this 
 way, by taking turns, we find it difficult to confer 
 over them, since all conference is now on the basis 
 of memory images, and, as we have already seen, 
 we find it difficult, if, indeed, not quite impossible, 
 to call up clear and persistent images of the im- 
 pressions afforded by these senses. 
 
 It IS true of some of these senses that in their 
 
i88 THE SENSE OF TASTE 
 
 enjoyment the stimulus itself is consumed. When- 
 ever this is the case the sense concerned will be 
 found to be one of the so-called lower, unssthetic 
 senses. Not only is social experience of the en- 
 joyable object impossible, but even the single 
 individual cannot himself get the experience 
 again. Can it be, perhaps, that, as Thorndike 
 remarks, " the pleasures of taste are not called 
 aesthetic because one cannot eat his cake and have 
 it, too "? It begins now to look as though only 
 those sense impressions can become aesthetic 
 vehicles which somehow lead beyond themselves, 
 and beyond the immediate gratification of the 
 individual, and facilitate some sort of social oper- 
 ation, or conference, or participation. In saying 
 this we do not have reference to the doctrine that 
 one often hears emphasized, — viz., that the lower 
 senses, such as taste, are low and unaesthetic be- 
 cause they minister mainly to our personal and 
 physiological needs. Nothing could be farther 
 from the truth. It is not because taste, smell, and 
 touch are mainly concerned in telling us of facts 
 that are of fundamental vital importance to us 
 as individuals that they are low or unaesthetic, 
 but only because they do nothing more than this, 
 — ^because they cannot become the vehicle of our 
 individual and social conference and communica- 
 tion. 
 
 In this connection let me quote an illuminating 
 
ESTHETIC VALUE OF TASTE 189 
 
 comment from Miss Calkins' chapter on " Per- 
 ception " in her " Introduction to Psychology." 
 As she there writes: 
 
 "It thus appears that even perception, the conscious- 
 ness, as we call it, of outer things, is a consciousness 
 of other selves as sharing our experience, a relatively 
 altruistic, not an exclusively egoistic mode of con- 
 sciousness. This is the reason why we usually speak of 
 sight and hearing and smell as higher senses — and in 
 the order named — than taste and the dermal sense 
 experiences. Vision is the sense most readily shared 
 by any number of selves : for example, everybody 
 within a very wide area may see the mountain on the 
 horizon or the Milky Way in the evening sky. Next 
 to vision, sounds are the most frequently shared ex- 
 periences; millions of people hear the same thunder 
 and thousands may share the same concert. Even 
 odors, though shared by fewer people, may be com- 
 mon to very many, whereas tastes and pressures and 
 pains, which require actual bodily contact, and warmth 
 and cold, whose physiological stimulation depends on 
 conditions of the individual body, are far less invari- 
 ably shared experiences. But the shared experiences 
 are those that are described, discussed, repeated, meas- 
 ured — in other words, those that are creatively re- 
 embodied in works of art and in scientific investiga- 
 tions. Vision, therefore, is a higher sense than the 
 others, only in so far as it is more often shared, and 
 hence more often discussed and described, measured 
 and verified. This is the reason why it is a more sig- 
 nificant social material of intercourse, art, and science. 
 Pressure and warmth, on the other hand, are less 
 valued, because they are less often actually shared and, 
 therefore, less easily verified and less frequently de- 
 scribed." 
 
I90 THE SENSE OF TASTE 
 
 This, we have said, is an illuminating para- 
 graph. But it is satisfactory only when amplified 
 in certain ways to which we seem to have been 
 led in our preceding discussion. Thus, it cannot 
 be said that the socially shared sense impressions 
 are chosen as the raw material of the fine arts 
 merely because they enable a multiplication of 
 individual pleasures. The dominant passion of 
 the artist is not merely to afford pleasure to the 
 greatest possible number of observers. But so 
 long as art is defined as an attempt to please, that 
 is about all that follows from the social character 
 of the higher senses. As a matter of fact, artists 
 do not seek to please the greatest possible number 
 of observers. They are often contented if a 
 single observer is satisfied. And by satisfied, in 
 this connection, one does not mean pleased. We 
 have already seen that the most pleasing of all 
 sense impressions are those afforded by the lower 
 senses. If the mere production of pleasure is 
 the chief aim of the artist, he would surely have 
 resorted to those materials which in themselves 
 and by their own direct effects facilitated his 
 purpose. 
 
 The Unsystematic Relations of Taste Qualities 
 
 Another characteristic of those sense materials 
 which enter into art products, — especially vision 
 and hearing, — is the fact that the various experi- 
 
.ESTHETIC VALUE OF TASTE 191 
 
 ences constituting the sense manifold exhibit struc- 
 tural and systematic relationships. We do not 
 here refer to the possibility of spatial arrange- 
 ment and form. This we have already discussed 
 and dismissed as an inadequate criterion. We 
 mean, rather, those facts represented, in the case 
 of vision, by the color pyramid and similar 
 schemes for representing the qualitative relations 
 of visual sensations; and, in the case of sound, 
 by the tonal scale and such graded intensity scales 
 as may be devised. Definite and formulable rela- 
 tions with respect to such facts as fusion, har- 
 mony, tonality, and melody; saturation, contrast, 
 complementariness, mixture, etc., may be made 
 out in the cases of vision and hearing. Esthetic 
 manipulation takes the form of playing upon these 
 relationships. The visual and auditory qualities 
 constitute not merely a manifold, but yield sys- 
 tematic structures. But the sense of taste and 
 the other lower sensation modes tend to consti- 
 tute a mere unorganized manifold. 
 
 Now, it may be at once suggested that we here 
 have the adequate criterion of the aesthetic for 
 which we are searching, and that this is at bottom 
 the reason why it is the visual and auditory ex- 
 periences that are " described, discussed, re- 
 peated, and measured (and) creatively reera- 
 bodied in works of art." 
 
 But even this account is, as a matter of fact, 
 
192 THE SENSE OF TASTE 
 
 very one-sided and in part, at least, fallacious. 
 We do not know what structural systems would 
 be exhibited by the lower sense experiences if we 
 had only discussed them, measured them, and 
 creatively embodied them to the degree to which 
 we have gone in the case of the higher senses. We 
 cannot be sure, in the present state of our knowl- 
 edge, to what degree the appearance of superior 
 organization on the part of the higher senses is 
 due to the amount of effort and inquiry we have 
 bestowed upon their examination. All that we 
 really know is that innumerable studies have been 
 made of sight and sound, and that we are able to 
 represent their results in the form of schemes and 
 systems; whereas, comparatively few studies of 
 the intensive type have been made of the various 
 " lower senses," and we are proportionately un- 
 able to construct the corresponding schemes and 
 structures. Which is cause and which is effect? 
 Do the lower senses fail to provide the raw ma- 
 terials of aesthetic construction because of their 
 lack of elaborate and systematic organization, 
 or do they owe this very deficiency to the relative 
 neglect they have suffered at the hands of the 
 artist ? 
 
 The Motive of Esthetic Products 
 
 There is some further reason why the esthetic 
 sense impressions are those which are genetically 
 
.ESTHETIC VALUE OF TASTE 193 
 
 most recent, in imagination the most capable of 
 clear and persistent revival, pertaining mainly to 
 the distance receptors, informing us of objects 
 which may be socially shared, and capable of sys- 
 tematic and organized description. It seems that 
 this reason is simply that the main thing about 
 an assthetic presentation, arrangement, or com- 
 position Is, after all, its intellectual content, its 
 " message." The artist desires, above all, to elimi- 
 nate our own immediate and instinctive reactions 
 to his materials. In so far as he is an artist, he 
 is not satisfied with presenting to us a pleasing 
 array of sense materials. His main concern is 
 in communicating to his observers some situation, 
 some theme, some state of affairs, some meaning, 
 some purely relational fact. Such emotions as 
 are stirred in us he does not wish to come from 
 his mere materials, but from his own manipula- 
 tion of them, from the form or pattern which he 
 gives them, from the meaning which he thereby 
 conveys to us. The true artist, in other words, is 
 neither a chemist, nor an athlete, nor a technician 
 of any sort whatsoever, but a philosopher. 
 
 Stout makes a similar comment when he says : 
 " The distinction between what we call the 
 higher and lower senses rests on this contrast be- 
 tween the intrinsic impressiveness of sensations 
 and their value for perceptual consciousness. 
 . . . The relatively higher senses deserve this 
 
194 THE SENSE OF TASTE 
 
 title in proportion as they are more delicately dis- 
 criminative and more capable of being combined 
 in successive and simultaneous groups and series, 
 while preserving their distinctive differences. On 
 the other hand, each several sensation is propor- 
 tionately less important through its own intensity 
 and pleasant or painful character. Any direct 
 effect produced by its own intrinsic intensity and 
 affective tone would Interfere with its value as a 
 vehicle of meaning — as an indication of some- 
 thing beyond its own existence. Thus, as per- 
 ceptual consciousness becomes relatively more 
 prominent and important, sensation is more deli- 
 cately differentiated, more definitely restricted, 
 less Intense, and less strongly toned in the way of 
 pleasure and pain." 
 
 The comments one is offered in the books on 
 " art," — eulogies of Raphael's rich color tones, 
 Rembrandt's lights and shadows, Rubens' flesh 
 tints, Meissonier's minute details. Turner's accu- 
 rate reproduction of ferns and mosses, smoke 
 and fog, and so on, represent a deliberate degra- 
 dation of the work of the artist to the level of 
 cookery, the manufacture of perfumery, dye- 
 stuffs, and the operation of merry-go-rounds. It 
 is crediting the artist with just that result which 
 Esthetic manipulation has always sought not to 
 produce, — the presentation of sense materials, 
 which of their own right awaken strong feeling 
 
ESTHETIC VALUE OF TASTE 195 
 
 tone in the observer. When George Frederick 
 Watts attempted, beyond those before him, to 
 convey meaning through his arrangements of 
 sense impressions he refused to attend minutely 
 to the details of technique, and critics subsequently 
 said of him, " His technique is faulty." Perhaps 
 it was, but that is the sort of comment one passes 
 on an athlete, a ventriloquist, or a juggler. One 
 might just as significantly criticize the literary 
 style of a mathematician or a logician as the tech- 
 nique of an artist. Such criticisms, to be sure, have 
 a legitimate place in life. But the critic of the 
 mathematician's literary style should not delude 
 himself Into the belief that he is discussing mathe- 
 matics, nor the critic of the artist's technique fancy 
 that he Is dealing with his art. For the real artist 
 is a philosopher, and that is the reason why the 
 lower senses are unssthetic. 
 
INDEX 
 
 Abnormalities, of taste, 97, 
 
 123 ff-. 151 ff- 
 Acetate of lead, 4 
 Acid, 5 
 Adaptation, phenomena of, 48 
 
 tendency to, 180 
 Addams, 159 
 ■Esthetics, motive of products, 
 
 192 
 Esthetic value, of the senses, 
 
 168 ff. 
 Affective value, of sensory 
 
 qualities, 182 ff. 
 After images, nature of, 37 
 
 of taste, 39 
 Ageusia, 152 
 Alkaline, taste, 2o 
 Alkaloids, taste of, 5 
 Allotriophagia, 157 
 Annelids, sense organs of, 133 
 Antagonism, of colors, 30 
 
 of tastes, 31 
 Appetite, i64ff. 
 Apple, taste of, 13 
 Areas, of taste, 23, 75 
 Art, and philosophy, 194 
 Aurx of taste, 151 
 
 Bailey, 45 
 
 Bain, 8 
 
 Bell, 134 
 
 Birds, senses of, 140 
 
 Bitter, 5, 7, 20, 21, 22, 31, 36, 
 
 40. 45. 47 
 Blends, of taste, 18, 29 
 Boyle, no 
 
 Brain center, for taste, 89 ff. 
 Brown, 150 
 Burton, 169 
 
 Calkins, 189 
 Camphor, taste of, 12 
 Cane sugar, taste of, 4 
 Cannon, 161 ' 
 Carlson, 163 
 
 Cells, supporting and gusta- 
 tory, 80, 108 
 Censorship, 173 
 Chatin, 7, i8 
 
 Chemical sense, 131, 135 ff. 
 Chemistry, i, 4, 78, 96, 99 
 Chevreul, 4, 12 
 Chinaglea, 58 
 
 Chloroform, taste of, 4, 13, 76 
 Chorda tympani, 87, 98 
 Classification, of tastes, 3 ff. 
 
 of papillae, 70 
 
 of taste stimuli, 96 
 Cocaine, 2i 
 Coffee, taste of, 13 
 Colloids, 5, 94, no 
 Colors, primary, 2 
 
 names of, 24 
 
 organization of, 27 
 Compensation, in colors, 30 
 
 in tastes, 31 
 Contrast, experience of, 34 
 
 laws of, 37 
 Crustacea, sense organs of, 134 
 Crystalloids, 5, 94, no 
 Cushing, 88 
 
 Development, of taste, s* ff-i 
 
 ii6ff., 143, 184 
 Digestion, and taste, 160 
 Discrimination, of tastes, 47 
 
 sharpness of, 175 
 Dreams, and taste, 124, 149, 
 186 
 
 197 
 
198 
 
 INDEX 
 
 Drugs, effect of, 20, 150 
 Duration, of sensations, 175 
 
 Electric stimulation, 100 
 Evolution, of senses, 52 
 
 of taste, 53, 116, 128 ff., 184 
 Eye, as sense organ, 9, 60 
 
 stimulus for, 11 1 
 
 Fatigue, 48 
 
 Fishes, senses of, 136 
 
 Flat worms, sense organs of, 
 
 Flavors, 18, 158 ff. 
 Foods, taste of, 16, 31 
 
 and flavors, 158 
 For el, 135 
 Fusion, of colors, 2 
 
 of tastes, 9, 18 
 
 Ganglion, nature of, 85 
 
 Gasserian, 86 
 Gastric juice, 161 ff. 
 Gley, III 
 Graham, 94, no 
 Guezer, 53 
 Gymnema, 21 
 
 Holler, 8 
 
 Hallucinations, of taste, 124, 
 
 149, 151 
 Heat, sensation of, 2 
 Hering, 113 
 Herrick, 137 
 Hornborg, 163 
 Humboldt, loi 
 
 Imagination, and taste, 144 ff., 
 
 185 
 Individual differences, 46, 
 
 122 ff. 
 Inertia, of sense organ, 55 
 Insects, senses of, 135 
 
 Kiesovi, 23, 30, 40, 41, $6, 75, 
 
 95. 99. 122 
 Kinaestbesis, 9, 10, 19, 34 
 
 Kroner, 53 
 Kuelpe, 41 
 Kussmaul, 53 
 
 Ladd, 18, 41 , 
 Lemonade, taste of, 29 
 Linnteus, 8 
 
 Magnesia, taste of, 5 
 Malacia, 156 
 Mammals, senses of, 141 
 Manifold, of sensations, 2 
 
 of taste, 3, 17 
 Meats, taste of, 16 
 Medusa, sense organs of, 132 
 Memory, and taste, 144 
 Mental images, nature of, 144 
 
 of taste, 146 
 
 classification of, 148 
 Mixture, of tastes, 28 
 Mode, of sensation, 7 
 Motive, of aesthetic products, 
 
 192 
 Muscles, of tongue, 66 
 Myers, 23 
 
 Nagel, 73, 76, 94, 97, 122, 125 
 Names, of tastes, 23 ff. 
 Nerves, of taste, 80, 83 ff., 115 
 Neurone, nature of, 82, 85 
 Nichols, 45 
 
 Oehrioall, 114 
 Onion, taste of, 13 
 Organization, of taste, 270., 
 190 
 
 Palate, sensitiveness of, 75 
 Papillae, stimulation of, 10, 22 
 
 sensitiveness of, 22 
 
 location of, 68 
 
 varieties of, 70 
 
 function of, 105 
 
 development of, Z17 
 Parker, 133, 138 
 Parorexia, 156 
 
INDEX 
 
 199 
 
 Patrick, 15 
 Pavlotii, 63, 161 
 Perception, nature of, 29 
 Periodic law, 5 
 Perversions, of taste, 156 
 Peterson, 53 
 
 Philosophy, and art, 196 
 Pica, 157 
 
 Potassium, taste of, 5 
 Primitive peoples, 23, iz6 
 Psychology, and classification, 
 
 6, ig 
 Psychophysical attributes, 
 
 174- flf. 
 
 Qualities, of taste, i 
 distribution of, 2i 
 of different senses, 175 
 
 Quinine, taste of, 13, 22, 32 
 
 Race differences, 126 
 Rainey, 53 
 Ramsay, 11 1 
 Reactions, instinctive, xi 
 
 time of, 56, 175 
 Reptiles, senses of, 139 
 Richet, III, 163 
 
 Saliva, flow of, 64, 93 
 Salivary glands, activity of, 
 
 62 
 
 function of, 103 
 Salt, s, ao, 22, 31, 36, 40, 45, 
 
 57 
 Sapidity, conditions of,_ ^3 ff. 
 Schema, of color qualities, 27 
 * of tones, 28 
 of tastes, 39 
 Sense organ, of taste, 60 fi., 75 
 
 development of, 116, 129 
 Senses, higher and lower, 
 168 ff. 
 aesthetic value of, i68 ff. 
 of lower animals, 132 ff. 
 development of, 132 
 Sensitiveness, of taste, 43, 53, 
 99 
 
 Sensitiveness, of tongue, 2i, 99 
 
 measures of, 43 
 
 varieties of, 44 
 
 of taste and smell, 46 
 
 of the cell, 13c 
 Sham feeding, 162 
 Sheldon, 138 
 Smell, sense organ of, 11 
 
 self-sacrificing character of, 
 
 loss of, 15 
 
 function of, 17 
 
 names for, 24 
 
 sensitiveness of, 46 
 
 adaptation to, 49 
 Social character, of senses, 187 
 Sour, 5, 20, 21, 22, 31, 36, 40, 
 
 45. 57 
 Spatial attributes, igi 
 Specific energy, of taste 
 
 nerves, 115 
 Stahr, 117 
 Sternberg, 96, 112 
 Stimulus, meaning of, 3 
 
 adaptation to, 48, 51 
 
 adequate and inadequate, 92 
 
 for taste, 92 ff., iii 
 Subjective tastes, 149 
 Sugar of lead, 5 
 Sttlzer, 100 
 
 Sweet, 5, 7, 20, 21, 31, 36, 40, 
 45, 57 
 
 Taste, acquirement of, 50 
 adaptation to, 49 
 ssthetic value of, 168 
 agreeableness of, 7, 24, 50, 
 
 biological role of, 158 
 blends of, 9, 18, 28 
 classification of, 3 ff. 
 contrasts of, 37 
 development of, 49, 116, 
 
 128 ff., 184 
 disorders of, 123 ff. 
 distribution of, 21, 73, 75, 
 
 123 
 
200 
 
 INDEX 
 
 Taste, in lower animals, 
 138 ff. 
 
 names for, 33 
 
 organ of, 60 
 
 organization of, 27 S. 
 
 poverty of, 14 
 
 qualities of, i 
 
 sensitiveness of, 43, 53 
 
 stimulus for, gz fiE., 105_ 
 Taste buds, characteristics of, 
 
 78 
 structure of, 79, 8z 
 function of, 107, 114 
 Temperature, effect of, 58, 99 
 Thorndike, 188 
 
 Threshold, of taste sensation, 
 44 
 
 Time, relations, 55 
 
 of reaction, 57 
 Tongue, as sense organ, 9, ai,. 
 61, 120 
 
 structure of, 65 
 
 movements of, 67, 103, 105 
 
 function of, 103 
 Touch, sense of, 9, xa, 19 
 
 Valentin, 45 
 
 Vegetables, taste of, x6 
 Vocabulary, of taste, aj 
 Volta, 101 
 
 Water, taste of, 150 
 Woodftaorth, 18, 41 
 fVundt, 8, 41, 142