We are not left to the unaided study of our mental processes for proof that the human brain is a mechanism. In the laboratory of Professor Goltz in Strasburg I saw a terrier from which he had removed, by repeated experiments, all the surface of the brain, thereby reducing the animal to a simple automaton. Looked at while lying in his stall, he seemed at first in no wise different from other dogs: he took food when offered to him, was fat, sleek and very quiet. When I approached him he took no notice of me, but when the assistant caught him by the tail he instantly became the embodiment of fury. He had not sufficient perceptive power to recognize the point of assault, so that his keeper, standing behind him, was not in danger. With flashing eyes and hair all erect the dog howled and barked furiously, incessantly snapping and biting, first on this side and then on that, tearing with his fore legs and in every way manifesting rage. When his tail was dropped by the attendant and his head touched, the storm at once subsided, the fury was turned into calm, and the animal, a few seconds before so rageful, was purring like a cat and stretching out its head for caresses. This curious process could be repeated indefinitely. Take hold of his tail, and instantly the storm broke out afresh: pat his head, and all was tenderness. It was possible to play at will with the passions of the animal by the slightest touches. During the Franco-German contest a French soldier was struck in the head with a bullet and left on the field for dead, but subsequently showed sufficient life to cause him to be carried to the hospital, where he finally recovered his general health, but remained in a mental state very similar to that of Professor Goltz's dog. As he walked about the rooms and corridors of the soldiers' home in Paris he appeared to the stranger like an ordinary man, unless it were in his apathetic manner. When his comrades were called to the dinner-table he followed, sat down with them, and, the food being placed upon his plate and a knife and fork in his hands, would commence to eat. That this was not done in obedience to thought or knowledge was shown by the fact that his dinner could be at once interrupted by awakening a new train of feeling by a new external impulse. Put a crooked stick resembling a gun into his hand, and at once the man was seized with a rage comparable to that produced in the Strasburg dog by taking hold of his tail. The fury of conflict was on him: with a loud yell he would recommence the skirmish in which he had been wounded, and, crying to his comrades, would make a rush at the supposed assailant. Take the stick out of his hand, and at once his apathy would settle upon him; give him a knife and fork, and, whether at the table or elsewhere, he would make the motions of eating; hand him a spade, and he would begin to dig. It is plain that the impulse produced by seeing his comrades move to the dining-room started