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although, with the exception of the sexual or- the process of recognition is characterized by
gans, it is difficult to say whether they produce the presence of a definite mood and the specific
any real sensations apart from those already qualities of our various moods are by general
mentioned. The respiratory, circulatory, ali- consent of psychologists determined by the
mentary and sexual sensations are sometimes presence of definite organic sensations.
spoken of as the vital sensations.”

Ribot and others urge furthermore the
The semi-circular canals together with the existence of affective memory. By this they
vestibular portion of the internal ear are com- mean that in addition to our ability to recall
monly regarded as responsible for our impres- ideas and in addition to our ability to remember
sions of the movement of the body as a whole; whether any given past experience was agree-
but it seems certain that under ordinary condi- able or disagreeable, we possess the capacity
tions other senses contribute to these impres- actually to reinstate in some measure the origi-
sions and only in the case of dizziness is it at nal affective coloring of a past experience. This
all clear that the sensations themselves are dif- is brought about, they maintain, either by our
ferent from those hitherto mentioned. It is in capacity freshly to arouse the organic sensations
any case reasonably certain that these organs which originally belonged to the experience, or
constitute part of a reflex system by means of by our ability to arouse the images or mental
which the body equilibrium is maintained. copies of these sensations. Certain psycholo-

The term common sensation, or sometimes gists deny the existence of these images. Withcommon feeling, has been applied more or less out attempting a discussion of the merits of this indefinitely to this whole organic group of sen

doctrine it is safe to say that individuals vary sations with special reference to the fact that vastly in the degree to which they actually our general feelings of vigor, health, discomfort, possess this capacity of fresh arousal of either depression and so on depend upon them. When ihe organic images or sensations characterizing these terms are used at present they are more

a former experience. commonly applied to sensations like pressure

Aside from the particulars already menand pain, which are conceived as widely dis- tioned organic sensations possess small value tributed over the body and therefore as more or for the cognitive side of mental life. They less common to the impressions gained from bring us relatively little exact knowledge and various sense organs.

in conditions of health come only infrequently Organic sensations are undoubtedly depend

to clear consciousness. On the other hand they ent like other sensations on the stimulations

are ordinarily marked with distinct feeling-tone, of sensory end-organs connected with centrip- are definitely agreeable or disagreeable. Under etal neural pathways leading to the brain.

conditions of health they seem to afford the These end-organs instead of being placed upon

basis of our feeling of well-being, a feeling the surface of the body, like those of the more

which is sometimes vivid but usually dim and familiar senses, are imbedded in the various vague. They are very disagreeable and painful deep-lying tissues of the organism. A marked when the bodily processes are overtaxed or peculiarity of many of these sensations is their disturbed in any way and it is in connection tendency to set up massive, widespread irradi- with such experiences that we most often find ating effects often quite remote from the seat of

them coming distinctly into the foreground of stimulation. This is probably brought about by

the mind. The discomfort of indigestion, ex-
means of the intimate connections of many of

treme fatigue and headache will illustrate the
these organic sensory nerves with the sympa-
thetic nervous system. This is less true of the Although their value for our knowledge
kinæsthetic sensations and certain forms of pre- processes is small, their significance for the life
sure than of the remaining members of the of impulse and volition is tremendous. The two
group. Pain affords many striking instances. great impulses represented by hunger and sex
The organic sensations play an extremely

may suffice to illustrate this side of the subject.
important part in the phenomena of feeling and All our processes of will and the whole sub-
emotion. In such emotions, for example, as structure of character are honeycombed with
fear and anger it is clear that a large part of

influences which originate in these impulses, and the content of our feeling is made up by sensa

the impulses themselves are but the motor extions of this character, e.g., sensations of tin

pressions of stimulations from organic sensa-
gling or flushing, which come from circulatory

changes in the skin, painful sensations from the Bibliography. - Beaunis, 'Les sensations in-
region of the heart, sensations of choking which ternes) (Paris 1899); Titchener, (Text-book of
come from the respiratory passages, sensations

Psychology) (New York 1911); Ebbinghaus,
of trembling which come from the motor Grundzüge der Psychologie (Leipzig 1897–
mechanisms, and so The James-Lange 1902); Stout, Manual of Psychology (London
theory of emotion makes the reflex stimulation 1898-99); Bain, Senses and Intellect' (Lon-
of these organic sensations the cardinal fact

don 1855). in emotion whereby, it is distinguished from

other forms of consciousness.

President of Yale University, New Haven,
These sensations are also held to possess

distinct significance for the processes of memory

SENSATIONALISM, in philosophy the and recognition. It is thus maintained by cer- doctrine that our ideas originate solely in tain authorities that the characteristic psycho- sensation and consist of sensations transformed logical process when we recognize a familiar Locke has been classed with Condillac and object is found in the arousal of certain of other philosophers of the 18th century as holdthese organic sensations which are called forth ing the doctrine of sensationalism; but Locke by familiar objects, whereas a different set of teaches that all human thoughts, even the organic qualities is aroused by unfamiliar ob- most complex and abstract, are due to exjects. It seems fairly certain in any event that perience: they are all made up of «simple

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ideas, and are due to phenomena of which cerebral process of image-reproduction, etc., we are percipient in the five senses, or else they which is normally aroused in the absence of are due to reflection on the operations of the stimulation. It is at all times a very great admind.” Condillac most distinctly refers all ideas vantage in thinking to recall that the terms to sensation. He supposes a statue organized “sense, «sensation, and even "matter) are, within like a man, but as yet without sensibility. after all, at best concepts arrived at through a He endows this statue with one sense after an- process of abstraction. For even so great a other till it becomes perfectly a human being, psycho-physicist as Ernst Mach (to cite one and holds that it then would possess exactly the example) used «sensation as synonymous with same ideas as ourselves, though in its first state (reality) itself. Man generalizes, he marks and it had no ideas.

describes those features which a set of events SENSE-ORGANS. See ANATOMY, Com

has in common; but while generalizations are

symbolized by mere words they deal with the PARATIVE.

events which are aglow with life or action. SENSES, in psycho-physics, anatomy, phys- "Sense," "sensation and matter" are such meniological-psychology and in philosophy, special- tal symbols, and they represent not the whole of ized nervous apparatus and the psychological reality, but at most only a single set of its process by the stimulation of which (or its features respectively. equivalent) qualitatively distinct sensations are Organism developed from protoplasm whose produced. Sense is equivalent to the Latin potentialities are four in number; and an organword "sensus,»* the Italian senso, the French ism whose histologic units are four would “sens, and the German sinn.) A sensation seem to have also four psychic facultative manifor to understand the import of «sense it is festations. Irritability, contractibility, metabolnecessary that one should understand «sensa

ism and reproduction in the cell correspond to tion” also -- is that process of nervous or quasi- epithelium, muscle, connective tissue and nernervous irritation which can only be accounted vous tissue in higher animal forms. In the for by the present operation of a stimulus or mind they become sense, will, understanding its equivalent upon a sentient being. It is the and ideation. Epithelium has its analogon in feeling that takes place while a sense-impres- (sense,? and ideation, its parallel in tissue sion is made. A sense-impression the effect formation," or "reproduction." of an event upon sentiency. What is that sense- Professor Ernst Haeckel in one truly properceived something, an event in which affects found lecture, beautifully explains how each sentiency? It must be answered that it is des- animal cell, and even each plant cell, is enignated by what is really one of the vaguest dowed with a peculiar kind of soul-life) of its concepts in the whole realm of thought, an ab- own. In higher animal forms, he tells us, there stract notion, the idea of matter. For present are formed through division of work special purposes we shall define matter as anything "soul-cells" of "nervous-substance.) The lower which can affect the senses. Upon which motion we descend in the animal series the more the we may build up one conception of "sentiency, nervous system is simplified, and more, too, the and define it as the matter perceiving, as an nervous elements separate from each other, until American philosopher, Dr. Paul Carus, defined finally they disappear merged in the mass of an it.

undifferentiated organism. It is the same with The use of (sense) as equivalent to "con

all the other apparatus, with all the anatomical sciousness," as in the phrases "time-sense, elements; and it would be as absurd to refuse (sense of responsibility, and in (sense of the

sentiency to an animal because it has no brain, heart) (the so-called occult sense of the mystic,

as to declare it incapable of nourishing itself Jonathan Edwards, who claimed by it one might

because it has no stomach. Sentiency itself know spiritual worth, truth, etc., by a kind of

originates through contact and interaction of intuition), is confusing and inaccurate. (Con

matter with matter. And the truth is that the sult Baldwin, Dictionary'). States of con

nervous system arises like other systems from sciousness are nothing but the states of aware- division of labor. Lower creatures ness or feelings connected with not only sensa

tient, the higher brute animals conscious, but tion, but also with perceptions, ideas and voli

self-consciousness is found only in man who tions. These states constitute the entire (sub

alone is aware that he knows. ject.” Memory and imagination are at times de- To Demosthenes, the eloquent orator of fined as senses internal senses; but this dis- classic antiquity, is ascribed the statement that tinction is psychologically of no particular im- all the senses are modifications of the sense of portance. Sensation (in German "Empfindung," touch. Sentiency is always an awareness of in French "sensation, and in Italian "sensa- objects in external material existence. So zione"), is a word confined by definition to is it with the

Kant disthose sense-impressions fully realized in con- tinguishes two sources of knowledge sciousness, and this definition excludes the

tion and pure

Sensations are in

cidental and particular; come us singly * One may recall that the Latin names of the five senses, with the word " itself, are all of the fourth declension

in a haphazard way and without affording in that tongue, and are thus nouns having one form only to any information concerning a necessary conexpress both numbers. Awkward as is any form of these

nection. The character of pure reason alone Latin words in English, students have come to it, and speak and even of " visuses," sensus," visus,

is the intrinsic necessity and universality of its auditus,"

and “tactus,

statements. The sequence in which the speemployed as Latin or as English words, are, however, all Louns which reveal number only in the accidence of words

cialized apparatus of each sense appeared in the with which they are grammatically connected. See the pro- evolutionary process is unknown. Touch, taste, test of H. H. Wilder, Desmognathus Huscus (sic)", in sight, hearing and smell are at times said to Science (19 April 1918, New York); and the Reply of Professor Wilder by T. L. Casey in the same journal (21 June

represent that sequence. The senses originated 1918).

through irritation received at the periphery of

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an organism. Taste is most highly differentiated in man, Sight is perhaps keenest in birds and bees. Hearing is the strongest faculty of the hare. Smell is the peculiar faculty of the bloodhound and of the ant. Touch attains a high degree of perfection in the trunk of the elephant. The bee is sometimes said to possess a peculiar faculty, an "hygrometric sense, as it is named. This quality or power of the bee is attributed to the little animal owing to an inference based on its undeniable power to "detect” and avoid a coming storm.

It is just possible, however, that the bee employs sight rather than an hygrometric sense to detect the approach of storms, and to avoid them.

· Through experience, a nerve, the optic nerve, became adapted to waves of ether. There irritations are transferred to the optic ganglions, and there possibly the disturbance is accompanied by the awareness called light. So also a nerve, the auditory nerve, became adapted to air waves. The irritations effected by these waves are transferred to the auditory ganglion, where possibly the disturbance is accompanied by the feeling known as sound. All other nervous cells of specialized sense, whether olfactory (or of smell), gustatory (of taste), or tactile (of touch), arose in evolution and function in a way similar to the senses of sight and hearing. Along the whole line of nervous fibres, from the point where sense-impressions enter to the place where muscular contraction such as usually follows the transmission of a shock from sensory to motor nerves, there is, physiologically, one uninterrupted chain of nerve motion. Yet the feeling or consciousness which accompanies a sensation is no motion.

One does not exhaust the number of sensations, however, if indeed one does the number of the specialized senses, in any mere enumeration of the sense-organs. These latter are the eyes, ears, nose, tongue and skin. In addition to the sensations of vision, hearing, smelling, tasting and touching (all of which Aristotle enumerated long ago), are to be mentioned, if only for greater completeness, pressure, temperature, pleasure, pain, muscular sensations, sensations in the ears, and sensation from the inner contents of the body. Pain and pleasure (see IRRADIATION), muscle sense, sensations from the semi-circular canals and vestibules of the ear, hunger, thirst, sexual-sense, fatigue, and sensations from the visceral organs internal, or organic sensations. Suffocation, internal warmth and chilliness are others of the same class. In all one perceives the characters of ordinary sensation, the sense-process psychic function involved in the apprehension of anything by the senses.

As belonging to the outer world one speaks of sensations and their complexes arising in our own body as organic sensations, because we locate them in our own body. Examples are sensation of fatigue of our muscles, and the pressure and pain sensation of our inner organs. The relatively uniform elements of touch and organic sensations are distributed among sensations of pressure, warmth, cold and pain. In contradistinction to these, the special senses of hearing, seeing, smelling and tasting present an abundance of sensations, each of which according to its peculiar constitution is called a quality of sensation. Each such qual

ity is variable in its intensity. Qualities of sensations all refer to the objective world. Our own body, to which touch and organic sensations relate, forms in contradistinction to our consciousness (the subjective reality, our real selves) a part of the outer world;- nearest to us indeed, but still a mere part of the objective or external world. Subjective existence is constituted of those feelings or states of consciousness whose activity is no motion. Objective existence is represented by things whose activities are motions. Man has abstracted from a group of sense-perceptions an idea of his "body.” The group of facts so collectively designated as "body, the action of which appears in constant connection with and as a condition of our consciousness, is kept in health only through constant renewal of its waste products out of the resources of the objective world, of which it is a part.

Sensations, while they are psycho-physical processes normally due to actual stimulation, can occur without any stimulation being pres

Delirium and the manifold examples of what are wrongly called sense-illusions are cases in point. Audition colarée, which seems to associate sound with color, is an example of excessive associative power, a result of insufficient balance of associative capacity, whereby the less near is approached because of the loss of what commonly should have been associated. When an adult professes to perceive a color, for example, every time he hears a letter of the alphabet named, it is hypothetically safe to say that were an investigation undertaken, it might disclose that the colors which such an adult professes to "hear” are the very colors in which the letters were printed on the blocks from which as a child such an adult learned his letters. There is no recorded instance worthy of credit of what has been styled “sense-transference, either concerning people in the somnambulistic state (as has been claimed) or out of it. No person ever read, tasted, heard by the fingers, or the stomach or any parts of the body other than through those organs by which reading, tasting, hearing, as functions of the sense organs, are naturally performed. Those "higher) phenomena of clairvoyance prevision, retrovision, introvision and telepathy do not (in the ordinary sense of these words) exist at all. Mysticism of this sort colors the thought of only those people who in regard to some matters (spiritual have strong convictions based on no evidence. The recollection of a sensation is nearly the same (but not the same) as an original sensation. For were it a sensation with a present stimulus then one might actually freeze to death through frigid imagination. Such recollection resembles the original sensation only (as being like it) a psychic event. By means of our mental impressions through certain organs, ---sensory or sense-organs,- concerning the world of objects, including impressions concerning changes in the condition of our bodies: and nothing more. There is a telepathy, or "farfeeling, however, which does not stand in miraculous contradiction to the mechanical interconnection of cause and effect in the external world. In and through our eyes most distant stars are seen. Only in this scnse has telepathy any claim to recognition by scientific psychology. Yet the feeling fcature of sensations is

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purely subjective. Things are mirrored in our ternal objects of one's sensations are those seneyes; sounds are heard with our ears; and sations measured in terms of what we suppose abstract notions are formed mentally to repre- to be their causes. We no longer feel, owing sent them. It would of course be very absurd to long practice of projection, our sensations to expect that the things represented in a sen- as states of consciousness, but conceive of an suous-manifold should migrate bodily into our independent reality as given immediately. But heads; and yet it would be equally as absurd sensation is nevertheless only the psychical feaas some far feeling telepathists profess to be- ture of the data of experience, and in the idea lieve, that things or objects in the external of a sensation, the material and physical stimuworld could be felt without the normal use lus is excluded. All one's sensations are in of the sensory organs.

one's self, not in their cause. We are conscious Though no animal has specialized more primarily of our self-sensing and of our feelsenses than five, many are much more spar- ings; and not with the objective world. What ingly endowed. Of very great importance as man knows of his environment is all pure deregards our enjoyments and our sufferings all duction from his own conscious states, particuknowledge besides has its roots in sensation. larly deductions from the feelings attending "All our knowledge, observed Gassendi long sensations. All these deductions serve ago to Descartes, “appears plainly to derive its other purpose than that of the explanation of origin from the senses, and though you deny these sensations in terms of what we affirm to the maxim Quicquid est in intellectu processe be their causes. Into that side of human condebere in sensu,' yet this maxim appears never- sciousness in which reasoned reflection has no theless to be true; since our knowledge is all part, the vast contexture of material existence ultimately obtained by an influx or incussion finds entrance in terms of sound, color, taste, from things external; which knowledge after- cold, heat, resistance, weight, hardness, shape, ward undergoes various modifications by means situation and motion. Whatever one can know of analogy, comparison, division, amplification, of one's environment results when recourse has extenuation and other similar processes which been taken by one to causation, a concept it is unnecessary to enumerate.” (Gassendi, in yielded by pure reason, which causality having (Objectiones in Meditationem Secundam'). been projected into the external world, renders

Hallucination is a misinterpretation of sensa- an explanation of sensations possible. Boyle tions. The feelings are real enough in such long ago observed that whenever one speaks cases; but the representations conce

cerning what of experience correcting reason, one speaks are supposed to evoke these feelings are not improprly; for, he observes, it is reason itself valid. Sensations become precepts, many pre- that corrects reason with information supplied cepts of one kind become concepts. From these by experience. Here it should be noted that concepts by the help of the reason abstractions

man knows many natural phenomena not diare drawn. Thus all the objects of our sur- rectly observable through the senses; for exroundings are mirrored in their relation toward ample, the chemical constitution of the stars. us and among themselves in the living sub- The psychological characters of sensation stance of the brain.

considered without reference to the conditions Bergson attributes to intutition a peculiar of its production are hearing, vision, smelling, power. (Consult Creative Evolution, Eng- tasting and touching. All these (we infer) are lish trans. 1913). That there is something the effects of external causes or facts. They unique and new at every moment may be are so many subjective methods of representing granted. That it is also true that that this can- certain processes of the objective world. not be fully expressed by means of intellectual Even sensations are a kind of abstractions. concepts may be also granted. Only direct By abstractions are meant a singling out, and knowledge can acquaint us with what is unique isolating, a separation of sense impressions, so and new.

But direct acquaintance of this kind that they can be held for thought. Our eyes, is given fully in sensation and does not (as for example, abstracts certain ether vibrations Bergson contends) require any special mystical called light and transforms them into vision. faculty of intuition, for its apprehension. It The ears abstract only certain air vibrations is neither intellect nor intuition (in the Berg- and we transform them into sounds. The mussonian scnse), but sensation that supplies new cular sense abstracts resistance and we transdata. Bergson makes much of evolution. It form this into an idea of corporeality. The must be pointed out that it is only through the skin abstracts temperatures yielding elements intellect that evolution can be known. If the for our notions of heat and cold. So is it with intellect is misleading the whole of man's bio- all other sensations. They abstract certain fealogical ancestry which we know through the tures of reality, or facts, and impress us. intellect is presumably an erroneous inference. There is a firmly rooted muscular sense of Bergson's advocacy of intuition as against in- rest, uneasiness and of exertion. Various tellect is thus a self-stultification.

muscular efforts occurring in the head and face Kant distinguishes two sources of knowl- have become associated with definite emotions. edge — sensation and pure reason. Yet the ulti- The labial nasal, and ocular external coverings mate data of experience and the bases of all are muscles of expression. Certainly the vocal knowledge are sensations. These data of ex- muscles give the same kind of an expression, perience are the several states of consciousness, not visible but audible. (Consult T. H. Evans, the elements of which are the sensory impres- Some Curious Psychosensory Relationsions, which fully realized in consciousness are ships'). sensations. Experimenting with the purely There are no such things as illusions of formal is indeed a kind of experience, and may sense. What is illusory is only an inference be distinguished as inner experience, just to which the feeling elements give rise in senbecause it is not merely a subjective process, sation. The sensation and its feeling are real but idcal. Objectively and scientifically the ex- psychic events; and it is indeed only by some



reality not merely sensible that even dreams can be condemned. What is illusory is manifest only in misinterpretation of certain experierrar

!1s1on, hearing, taste, smell and touch depend upon certain stimulations from without;mechanical (touch), molecular (taste and smell), physical (sight and hearing), and muscular (muscular sensation). At times the required stimulation may be effected within the nervous system.

The cerebral processes by which vision (for example) is produced may not only be started in the brain itself, but when so started may result in those identical interpretations which normally accompany the process when ser at work by stimuli from the external world.

According to Roamnes there is a constant ratio between the amount of agitation produced in a sensory nerve and the intensity of the corresponding sensation. · Weber states that if sensations are to increase in intensity by equal amounts the stimulus must increase by relatively equal amounts. His law is that the perceptible increment of sensation is proportional to the quantity of irritation. More precisely: In most cases the quantity of sensation is proportional to the logarithm of the quantity of irritation. Further researches in this direction were undertaken by Fechner, Volkman and Appel; and to their works the students of the subject may be recommended. It is entirely true that we do not experience sensation in the sense-organs.

We feel the state of our nerves. The brain itself is the seat of all sensation.

Taste, smell, sight and hearing are operative because of special organs connected by special nerves with the brain. As to touch, while there are special organs, it is an unsettled question whether tactile sensations are conveyed by special nerves or by the ordinary sensory nerves of the skin. The organs of sense depend upon the alertness of the brain for efficiency. It is in fact the brain that sees, hears, etc. As sight, hearing and touch seem to be most concerned with the wants of the intellect, they are sometimes spoken of as the intellectual senses; while taste and smell, being intimately connected with nutrition, are known as the corporeal senses.

Cultivation of the senses, especially if begun in early life, will develop their usefulness. It produces the accurate hearing of the musician, the keen eyesight of the pilot, engineer and expert microscopist, and the accurate touch of the blind. But training may be carried to such an extent as to make these senses sources of misery. Certain persons are painfully conscious of the slightest discord; others almost instantaneously detect, with a feeling of disgust, the inharmonious blending of tints which, to the average person, are all in harmony; still' others are made uncomfortable by an odor perceptible to no one but themselves. All the senses become accustomed to continued impressions, so that they no longer perceive their existence. This condition may prove a source of danger, for one may, for example, become habituated to harmful odors. Sense-education of the feebleminded, as accomplished by Seguin and his wife, by "constant, assiduous, philosophical training," is a noteworthy achievement. It seems to be a rule, with but few exceptions, that when one

sense is lost or seriously impaired nature sharpens some other.

Touch, or tactile sensibility, enables us to appreciate by actual contact, the size, form and consistency of objects and the character of their surface. It is most sensitive in the margin of the lips, tip of the tongue, palms of the hands, and under surfaces of the fingers. Some writers speak of “general sensibility as one of the senses, and include under this term, touch, muscular sense or the sense of pressure, sense of temperature, etc. The organs of touch are endbulbs and tactile corpuscles. See MUSCLESENSATION.

Taste enables us to discover and recognize flavors. This sense resides in the tongue, soft palate, uvula, pillars of the fauces, tonsils and the upper part of the pharynx. The organs of taste are taste-bulbs and various papillæ. The nerves of taste are the gustatory branch of the fifth pair of cranial nerves and the lingual branch of the glosso-pharyngeal nerve. Only those substances can be tasted which are dissolved, and at the same time the mucous membrane of the mouth must be moist.

It is said that the German physiologist Valentin could detecta 100,000th solution of quinine. What we know of the different tastes are complex experiences made up of odors, motor experiences, pressure and pain sensations, visual elements and a far more lirnited number of taste elements than we suppose. Their number seems to be fou:: sweet, salt, sour, bitter. Of the physical stimuli of taste sensations we know even less than of the indefinite localized physiological organs of taste. Chemically different substances

may arouse the same sensational response; for example, both sugar and acetate of lead yield a (sweet” taste. Only one statement may be hazarded; namely, that the taste stimulus is always in a liquid form. Taste sensations and their brain area (little known) all involve attention, discrimination, judgment, and so on. The tongue tastes. It also feels. Aerated water is felt”; alum «draws) the tongue.

The most satisfactory classification of smells as we meet them in nature is that adopted from Linnæus by the Dutch physiologist, Zwaardemaker. It recognizes the following classes: (a) Etheral smells, including all fruit odors; (b) aromatic smells, like those of camphor, spices, lemon, rose; (c) fragrant smells, like those of flowers; (d) ambrosiac smells, like those of musk; (e) alliaceous smells, like those of garlic, assafætida fish; (f) empyreumatic smells, like those of tobacco and toast; (g) virulent smells, like that of opium; (h) nauseating smells, like that from decaying animal matter.

Many smells are of course like tastes obviously complex experiences containing elements of taste, touch and vision as well as sensations of smell. The "pungency of such smells as that of ammonia is a "touch" quality. Smell stimulus is gaseous, not liquid, and the property of stimulating the end-organs of smell is a function of the physical molecule, not of the atom, since most of the chemical elements are odorless.

Smell is the sense by which odors are perceived. The olfactory nerve is, like the optic nerve, a prolongation of the cerebrum. The olfactory bulb is at the anterior extremity of the


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