Page:Popular Science Monthly Volume 26.djvu/21

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11
MIND AND THE NERVOUS SYSTEM.

of years taught, in my course of lectures on diseases of the mind and nervous system, the doctrine now set forth that, wherever there is gray nerve-tissue in action, there is mind. Into the detail of these experiments it is scarcely proper on this occasion to enter; suffice it to say that they all go to establish the fact that the spinal cord, after the complete removal of the brain, has the power of perception and volition, and that the actions performed are to all intents and purposes as perfect of their kind as they would be were the brain in its place.

As I have said, it is difficult to perform experiments of the kind in question on warm-blooded animals, for the hæmorrhage that results in consequence of the necessary cutting operation soon leads to the loss of life; but, for all that, we are not without information on the subject, derived from investigations of some of the higher animals. You have, most of you, seen a decapitated chicken staggering and fluttering about the barn-yard. Whence comes the force by which its movements are made, unless from other organs than the brain? This is a rough experiment that is performed every day, but in the laboratory we do it in a more careful way, and the results are still more striking.

If the brain be entirely removed from a pigeon, the bird turns its head in accordance with the motion given to a lighted candle held before its eyes; it smooths its feathers with its bill when they are ruffled; it places its head under its wing when it sleeps; it opens its eyes when a loud noise is made close to its head. Onimus removed the brain from young ducks hatched and brought up by a chicken. These ducks had never been in the water, yet when placed in a basin they immediately began to swim. Their motions in swimming were as regular as in other ducks which had lived in the water. This series of experiments shows that even the inborn instinct of animals is not solely resident in the brain.

Now, when we come to man, and observe the experiments which are constantly being made for us, both in health and disease, we can not avoid placing the spinal cord much higher as a nerve-center than it is usually placed by physiologists.

In human anencephalic monsters, or those born without a brain, we have interesting examples of the fact that the spinal cord is possessed of perception and volitional power. Syme describes one of these beings which lived for six months. Though very feeble, it had the faculty of sucking, and the several functions of the body appeared to be well performed. Its eyes clearly perceived the light, and during the night it cried if the candle was allowed to go out. After death the cranium was opened, and there was found to be an entire absence of the cerebrum, the place of which was occupied by a quantity of serous fluid contained in the arachnoid. The cerebellum and pons Varolii were present. Panizza, of Pavia, reports the case of a male