Page:Popular Science Monthly Volume 26.djvu/20

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10
THE POPULAR SCIENCE MONTHLY.

evidence of perception and will? Would they not be movements performed with a definite purpose—the very best possible under the circumstances—to escape from the irritation, even though the brain were unconscious of them? It must be remembered that consciousness is not the necessary accompaniment of volition, as we shall presently see from examples I shall adduce; and this being the case, I can not avoid the conclusion that actions performed under the circumstances I have stated would be based upon perception and done through the power of volition.

Warm-blooded animals are for many reasons not suitable subjects for experiments such as are required in the study of the phenomena under consideration, but in some of the lower animals, as the frog, for instance, we find those conditions present which fit them for such investigations. Thus, if the entire brain be removed from a frog, the animal will continue to perform those functions which are immediately connected with the maintenance of life. The heart beats, the stomach digests, and the glands of the body continue to elaborate the several secretions proper to them. These actions are immediately due to the sympathetic system, though they soon cease if the spinal cord be materially injured. But, in addition, still more striking movements are effected—movements which are well calculated to excite astonishment in those who see them for the first time, and who have embraced the idea that all intelligence resides in the brain. For instance, if in such a frog the webs between the toes be pinched, the limb is immediately withdrawn; if the shoulder be scratched with a needle, the hindfoot of the same side is raised to remove the instrument; if the animal is held up by one leg, it struggles; if placed on its back—a position to which frogs have a great antipathy—it immediately turns over on its belly; if one foot be held firmly with a pair of forceps, the frog endeavors to draw it away; if unsuccessful, it places the other foot against the instrument and pushes firmly in the effort to remove it; still not succeeding, it writhes the body from side to side, and makes a movement forward.

All these and even more complicated motions are performed by the decapitated alligator, and in fact may be witnessed to some extent in all animals. I have repeatedly seen the headless body of the rattle-snake coil itself into a threatening attitude, and, when irritated, strike its bleeding trunk against the offending body. Upon one occasion, a teamster on the Western plains had decapitated one of these reptiles with his whip, and, while bending down to examine it more carefully, was struck by it full in the forehead; so powerful was the shock to his nervous system that he fainted and remained insensible for several minutes. According to Maine de Biran, Perrault reports that a viper whose head had been cut off moved determinedly toward its hole in the wall, I have performed a great many experiments and made numerous observations relative to the matter, and have for a number