[Footnote AK: There are some who believe they are warranted in concluding the opposite from the structure of the animal's brain alone. We may say that the brain of the horse, compared with that of the ape, or even that of the dog, represents a relatively low type of development. But owing to the rapid changes in the views, often contradictory, concerning the nature of the nervous structures and processes underlying the thought process, any conclusion based on such views would be premature. For this reason we cannot agree with the French physiologist who was dissecting the brain of a horse and, struck by its smallness of size, exclaimed: "When I saw your proud look and beautiful neck, I hesitated a moment before mounting upon your back. But now that I have seen how small is your brain, I no longer have any qualm about using you."[98]] To come now to the learning process itself;--we may assume that, at first, whenever the horse began to tap in response to commands, he would receive a reward for this purely mechanical feat. Wooden pins were then planted on the ground and designated as: one, one two, etc., and each time someone would raise the horse's foot as many times as the count demanded (see Supplement I). Then Mr. von Osten would take his stand at the horse's side and would command him, let us say, to tap 3. Hans noting merely (from his master's position) that he was expected to tap, would begin. The instructor, who had bent forward in order to watch the horse tapping,[AL] would involuntarily straighten up again at the third tap, without being conscious of it and quite unaware that he was thus giving a signal. The horse would be startled, and sometimes he would immediately cease tapping and sometimes not. But it was only in the first case that he would receive a reward. Thus, unknown to the instructor, an association became established between the sight of the upward jerk of the instructor and the act of ceasing to tap. To be sure, the animal would receive sundry visual impressions from the wooden pins set up before him and the auditory stimulations of the spoken number names, on the basis of which, the concepts were to be formed in his mind. But in this chaos of visual impressions (at times there were two wooden pins, then three, then four, sometimes there were the pins, at others, the balls of the counting-machine)--and in the babel of word-sounds--which evidently meant nothing but noise to him--amidst all this there was but one constant element: the final movement of the instructor's body. The moment the horse reacted to this, he would receive the tidbit at the hands of his overjoyed master, and thus he became more and more accustomed to attend to this jerk, even after it had gradually decreased in scope. And the reason again, why this jerk tended to become less pronounced was that the tests were gradually becoming more and more successful. For, corresponding to the degree in