astringent tastes, are in part the effects of tactual stimulation; feelings of relish and disgust are traceable to the sympathy of the alimentary canal; and sensations of smell also influence our estimation of the sapid qualities of many substances. The cognitional value of the sense is very low. Continuous stimulation rapidly deadens its sensibility; its recuperative power is tardy, its sensations are wanting in precision, and they can be but very imperfectly revived in imagination. The main grounds of its cognitive inferiority, however, lie in its essentially subjective character. Abstracting from the information afforded by concomitant tactual sensations, taste originally gives us no knowledge of external reality, and, consequently, with the exception of the vague systemic feelings of the organism, it must be ranked lowest as a medium of communication with the physical world. On the other hand, viewed from the standpoint of feeling, this sense is capable of intense but shortlived pleasure and pain. Though the lowest of our faculties in point of refinement, and the most subject to abuse, its great utility as a guide in the selection of food throughout the animal kingdom is evident.

SMELL.-Odorous particles emitted from gaseous or volatile substances constitute the appropriate stimulus of this sense. The organ of smell is the cutaneous membrane lining the inner surface of the nose. The action of the odorous substance is probably of a chemical character, and the simultaneous inhaling of the air is requisite for the

production of the sensation. In the act of inhalation the stimulating particles are drawn through the nostrils over the sensitive surface. Even the strongest smelling substances are not perceived as long as we hold our breath. This sense resembles that of taste in many respects. Vagueness is a marked feature of each; continuous excitation renders both obtuse; their recuperative power on the cessation of the stimulus is weak; and both are originally of a like subjective character. The close affinity of the two faculties is exhibited in the difficulty of determining how far the recognition of a particular substance is due to taste, and how far to smell; and in the readiness with which most of the adjectives, such as sweet, bitter, pungent, primarily qualifying sensations of taste, are transferred to those of smell. The attempt to distinguish port wine from sherry, apart from sight and smell, is a familiar method of illustrating the former. The delicate susceptibility of smell to some kinds of stimulation is, however, very surprising. The merest trace of a drop of oil of roses awakes a pleasurable feeling, and as infinitesimal a particle as the one thirty-millionth part of a grain of musk is perceptible. The delicacy of this faculty in the dog and other brute animals, as is well known, far exceeds what it attains in man. Just as in the case of taste, the sensations of smell may be of an extremely agreeable or disagreeable character. They stand

2 Cf. Bernstein, The Five Senses, p. 290. He says that some animals can, when the wind is favourable, scent the huntsman several miles away. The number and the minuteness of the volatile particles which proceed from objects perceivable at such distances pass comprehension.

higher, however, in order of refinement. They are, too, more easily revived in imagination; and, being awakened by objects at a distance, these sensations, like those of sight, assume the character of premonitory signs of other future experiences. In this way the sense of smell comes to surpass both organic and gustatory sensations, as an instrument of external perception.

TOUCH.-Under the generic sense of touch are comprised a variety of classes of feelings widely different from each other. Consequently, very early in the history of Psychology, we meet with discussions as to whether this term does not include several specifically distinct senses. Aristotle3 called attention both to the close relationship of taste with touch, and to the divergent nature of sensations of temperature, of softness and hardness, and of contact proper. It would certainly seem that sensations of temperature, differing so much in quality from those of touch proper, awakened, moreover, by distant objects, and seated either in different nerves or different properties of nerve, from those of our tactual feelings, have as strong claims to be considered the utterances of a separate sense as our gustatory states. Since, however, every proposed subdivision of touch into separate senses appears

3 Aristotle, in the De Anima II. 11. 22-24, holds a plurality of senses to be contained under the generic faculty of touch. Elsewhere, in the De Gen. Animalium, he seems to adopt the monistic view. St. Thomas, however, prefers to look on these sensations as merely different classes of feelings comprised under one tactual sense, the formal object of which has not received a definite name. Cf. Sum. i. q. 78. a. 3; also Schiffini, Disp. Metaph. Vol. I. p. 322.

open to grave objections, and since the question is really of no very great importance, the most convenient plan will be to distinguish and describe separately the leading modes of sensibility included under touch in its widest sense, without deciding whether they should be assigned to different faculties. These forms of consciousness are: (1) the organic sensations, (2) the sensations of temperature, (3) touch proper, and (4) the muscular sensations.

(1) The organic sensations, common sensibility, cœnasthesis, or the vital sense. Under these various designations are included the numerous modes of sensuous consciousness attached to the organism as a whole, or to particular portions of it. Their essential function is to inform us, not of the properties of the extra-organic world, but of the good or ill condition of our own body. Prominent among them are the systemic sensations, comprising those of the alimentary canal, such as the feelings of hunger, of thirst, and repletion, the sensations of respiration, of circulation, and such other states as are normal to the system. In addition to these, the chief remaining organic sensations are those arising from disease, and from laceration or fracture of any part of the organism. Estimated from a cognitional point of view, the organic sensations are of little importance. With the exception of particular hurts, they are of an indefinite and obscure character. They can be but very feebly reproduced in imagination. Being in great part beyond the range of touch and sight, they are vaguely and imperfectly localized, and they give us practically

no information regarding the external world. On the other hand, as sources of pleasure and pain, they possess immense influence over the tenour of our existence, and they are of the greatest utility as guardians of our physical health.

(2) Diffused throughout the organism as a whole, yet specially seated in the skin, the sense of temperature has claims to be grouped both with the organic sensations and with the sense of contact proper. Some writers have maintained that our consciousness of temperature is dependent on a set of nerves distinct from those employed in tactual sensation. This is not yet absolutely proved, but that the properties of the nerve-fibres involved are completely different is shown by the fact that either class of feelings may be almost entirely suspended, whilst the other remains comparatively unaffected. As our consciousness of temperature is relative to that of our own person, this sense can afford little assurance about the absolute heat or coldness of an external object. When the environment is of the same temperature with that of the part of our body exposed, we are unconscious of it. If we pass into the chill night air from a hot room, we are

4 Common Sensibility has, however, great importance from an intellectual standpoint in this respect, that it is the source of much error. It may seriously distort men's judgments. Peace and war have at times depended on the Prime Minister's digestion.

Recent ingenious experiments by Goldscheider and other physiologists, seem to show not merely that the nervous endapparatus of temperature sensations differs from that of pressure and of pain, but even that there are in the skin distinct "heat-spots and !! cold-spots"-minute localities sensitive to heat but not to cold, and conversely. This appears surprising when we recollect that to the physicist heat and cold are purely relative. Cf. Ladd, op. cit. pp. 346-350.