respiration is divided. He will fight as bitterly, but with no retraction of his lips, or sparkling of his eye, or drawing back of his ears. The face is inanimate, it does not partake of the action corresponding with the passion, though the muscles of the face and jaws, as far as they are liable to influence through other nerves, continue their offices. By cutting the same nerve in a cat it may be deprived of all expression. If the nerve of one side of the head be cut, as it comes out before the ear, we shall see no brilliancy in the eye from the action of the eyelids, no motion of the whiskers, nor spitting in anger; although all these signs be exhibited on the opposite side. If birds be deficient in expression, from the horny bill being substituted for the mouth and nostrils, yet they are not without some sign of passion in the rising and flutter of the feathers. The game cock, in the position of fighting, spreads a ruff of feathers round his head. The position of his head, and the feathers raised from his neck, are the expressions of hostile excitement. But on the division of the respiratory nerve the feathers are no longer raised, although the disposition to spar continues. The accidental injury or the disease of the respiratory nerve of the face of man exhibits the same consequences with these experiments on brutes. When the respiratory nerve is injured on one side, the individual can neither laugh nor weep with that side of с the face; then the slightest smile deforms the countenance, by the unequal action of the muscles; on that side where the nerve is entire in the performance of its office, the act of smiling takes place, while the muscles of the other remain inactive, and are drawn into distortions. In the former edition of these essays I had shown the number and complication of the muscles used as instruments of expression; but by these discoveries of distinct properties in the nerves, we see why there is a complication of nervous branches, in proportion not merely to the number of muscles to be called into action, but to the variety of uses to which they are put-the various combinations which they form, in alliance with different organs. It now appears, that by an apparatus of appropriate nerves, the muscles of the face, neck, and chest are drawn to co-operate in the act of respiration. But by these observations it is also proved, that it is through the nerves of respiration that the muscles become agents of expression; for although they can both act and feel after the respiratory nerves are cut, they no longer express passion, but remain tranquil during the utmost excess of suffering or of passion in the animal. When, therefore, we shall have proved that the organs of respiration are the organs of expression, as well as of speech, the mystery that hangs over this subject will disappear, and the motions of the countenance and of the frame of the body will be as intelligible as the natural expression of the voice. EXPLANATION OF PLATE I. BEING A VIEW OF THE NERVES OF THE HEAD. In this plate the two distinct classes of nerves which go to the face are represented; the one to bestow sensibility, and the other for the motions of speaking and expression, that is, the motions connected with the respiratory organs. The nerves on the side of the neck are also represented. These I have discovered to be double nerves, performing two functions; they control the muscular frame, and bestow sensibility upon the skin. Besides these regular spinal nerves, which are for the common endowments, the nerves of the throat are represented. These latter nerves are the chords of sympathy, which connect the motions of the neck and throat with the motions of the nostrils and lips; not merely during excited respiration, but in the expression of passion. |