attains a high degree of acuteness; and this endowment, together with other conformable arrangements and adaptations, invests the human hand with the character of a special organ of touch. A certain, though low degree of vital contractility, seems also to belong to the skin.'-QUAIN.

Of the other parts sensible to Touch, besides the skin, namely, the tongue and mouth, the needful description has been already furnished under the sense of Taste.

The nerves of touch are the sensory or posterior roots of the spinal nerves for the limbs and trunk, and certain of the cerebral nerves (the fifth pair) for the head, face, mouth, and tongue.*

5. The action in touch is known to be simple pressure. The contact of an object compresses the skin, and through it the embedded nerve filaments. That the squeezing or pinching of a nerve can produce sensibility is proved in many experiments in touch, the squeezing is of a more gentle nature, owing to the protection that the covering of skin gives to the nerves. The only point of interest connected with the mode of action is the singular fact, that very light contacts often produce a great sensibility, as the touch of a feather or of a loose hanging piece of dress, which sensibility is diminished by making the contact more intense. Great pressures yield comparatively little sensation in the skin; they are felt mainly in the muscles as a feeling of force and resistance.

This fact of the disproportion of the feeling to the pressure I can account for in no other way than by supposing, that great compression has an effect in deadening the conducting property of the nerve. We know from various observations that the compression of a nerve does tend to arrest its conductibility; the deadening of the sensibility of the hand by leaning the elbow on a table, so as to squeeze the nerve that

*It is supposed that the important nerves of touch in the extremities have a different course in the brain from the nerves of the trunk. Türk has shown that in the hand and foot the same spot is supplied from different roots in the spinal cord.

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passes near the surface on the elbow joint, is a familiar instance.

6. We come now to the sensations, or feelings of touch, which are various in kind, and have many of them a considerable degree of interest, from their bearing on the higher operations of mind. In the order of enumeration, I shall commence as usual (I.) with those having reference to pleasure or pain, or that may be called predominantly emotional.

Sensations of Soft Touch.-In this class of feelings, we suppose the gentle contact of some extended surface with the skin. I keep out of view the feeling of temperature. A good example is furnished by the contact of the under clothing with the general surface of the body, which is most perfect under the bed-clothes at night. The glove not too tight on the hand is another instance. The extended hand, resting on a cushion, or other soft body, is a sufficiently good type of the situation.

The resulting sensation is of the pleasurable kind, not acute, but massive. It closely resembles agreeable warmth. It is less powerful, but probably more retainable in idea, than the muscular or the digestive sensibilities. Its relationship to the tender emotion is elsewhere discussed. (THE EMOTIONS AND THE WILL, Tender Emotion.)

The habitual inattention to the sensibility of the clothing is a striking example of the law of Relativity. The remission of the contact is felt, on the same principle, as a sensation of blankness.

In the feelings of the lachrymal, mammary, and sexual organs, the mode of action appears to be something more than simple contact; the quality of the touching substance affects the sensation. In the tranquil flow of the lachrymal fluid, under genial tender emotion, there is a certain amount of agreeable sensation in the eye; but when the eyes are flooded in profuse grief, the contact of the liquid with the eye-lids is scarcely pleasurable. There is probably, if not a chemical, at least a dialytical action on the sensitive surfaces, in those instances.

The mutual contact of living animal bodies yields a complex sensation of softness and warmth, and excites the corresponding emotions. There may be, in addition, magnetic or electric influences of a genial kind, but the reality of such currents is by no means established.

The attraction between the mother and offspring is partly grounded upon the pleasure of the soft warm contact. This keeps the new-born animal by the mother's side, before it has come under the farther gratification of being fed and nourished; and continues to co-operate with that still more powerful motive to close proximity. At a later period, the contact of the opposite sexes, stimulated, in the first instance, by the pleasure of mere touch, discloses and inspires in each the sexual urgencies, and the tentatives for gratifying them.

Many of the habitual attitudes and modes of outward expression are regulated by the pleasure of soft touch. The child puts its finger or hand to its mouth, either for the mere pleasure of the act, or as a comforting sensation in distress; and all through life the contact of the hand with the parts of the face is practised from the same motives. Many other attitudes and actions are governed by the pleasures of touch; some, as scratching the head, are apparently the search for

pungency.

7. Pungent and painful Sensations of Touch.—When, instead of a diffusive soft contact, we have an intense action on limited spots, mere points, as in the stroke of a whip, a sensation of smartness is produced very different from the above. In moderate degree, this gives a pleasurable pungency, beyond which it is acutely painful. The nerves are shocked as by the prick of an instrument, and the overintensity and suddenness of the stimulus is a cause of pain. The nature of the sensation is not radically different from a cut in the skin; its peculiar smartness excites the whole system. It prompts the most decisive actions for avoiding the pain, and an intense mental aversion to all that relates to it. The intensity gives to it a hold on the memory not possessed by the luxurious feeling of diffused softness.

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Hence the efficacy of skin inflictions in the discipline of sensitive beings.

Other things being the same, the sensibility of the skin to these two classes of feelings is greatest in parts most richly supplied with nerves, and where the discriminative or tactile sensibility is greatest, as in the tongue, the lips, and the palm of the hand.

8. Other painful Sensations of the Skin.-Among these I would first advert to the sensation of tickling. On this Weber remarks, that the lips, the walls of the nasal openings, and the face generally, when touched with a feather, give the peculiar sensation of tickling, which continues till the part is rubbed by the hand. In the nose, the irritation leads at last to sneezing. The excitation extends to the ducts of the glands, which pour out their contents, and increase the irritation. The violent commotion produced by bodies in contact with the eye, is of the nature of tickling, accompanied by a flow from the glands, and readily passing into pain. Why some places are liable to this sensation, and others not, it is difficult to explain. The possession of delicate tactual discrimination is not necessary to the effect.

The singularity of tickling is the fact that a very trifling sensation prompts to extraordinary efforts of the will for deliverance. The tickling of the arm-pit, or the soles of a susceptible person, is as violently repudiated as the touch of a scalding surface.

There is one consideration that may help to account for the anomaly. It is the nature of tickling to stimulate intense reflex movements; these are, on their own account, a source of massive discomfort and repugnance. The same tactile feeling, if unaccompanied with reflex stimulation, might be wholly indifferent. This remark may apply to the tickling that precedes laughing and sneezing. The irritation of the fauces brings about, in the first instance, reflex contractions of the muscles of the throat; these are more or less acutely painful; thereupon, we give way to the farther impulse to spasmodic expiration.

Possibly the same explanation may be extended to the chafing and fretting of the skin, when too slight to be painful as a pungent smart. A reflex stimulus is applied when the nervous system is irritable, and when forced muscular movements would be painful and repugnant. It is not the sensation by itself that we dread, but the wakening up of activity when we are courting repose and quiescence.

All the parts of the skin are liable to yield painful sensations, especially under injury or distemper. The epidermis is itself insensible, but the true skin is extremely alive to feeling. When lacerated, chafed, or burnt, it causes acute pains. Its capillary vessels and numerous sweat glands and oil glands are, in all probability, the source of pleasurable or painful organic sensations. The long continued compression of the same part of the skin creates uneasiness. The hairs are themselves insensible, but by their attachment to the skin they are the media of sensation. The place of attachment of the nails is the seat of a violent form of acute pain, which has a facility of seizing on the imagination, and of exciting revulsion even in idea.

Clamminess is a distinct sensation arising from the adhesion of a substance to the skin, and is an uneasy feeling, the uneasiness being due to some interruption of the natural functions of the part.

9. (II.) Sensations of Temperature.-The feelings of heat and cold are most powerfully felt in the skin; the sensitiveness also extending to the gullet, the stomach, and the rectum. There is no reason for supposing that any other nerves than those of touch are needed to a rouse a sensation of warmth or of coolness. As to the mode of action, heat being a state of molecular motion will impart molecular disturbance to the nerves, and thus operate as a stimulant, favourably or unfavourably according to the circumstances.*

* Sir William Hamilton thinks it probable that the sensation of heat depends on a peculiar set of nerves, for two reasons: 1st, Because certain sentient parts of the body are insensible to this feeling; and, 2nd, Because I have met with cases recorded, in which, while sensibility in general was