This theory, the simplicity of which certainly must make a strong appeal, has been adopted by a number of well-known investigators (Schleich[40], Koenigshoefer[41]). If we also could accept it, then Hans's phenomenal power of perceiving the movements of objects would be explained. But doubts arise which restrain us. Even if we were to accept Berlin's view in general, we should still come upon the following difficulties. In the first place, it is questionable whether the peculiar form of astigmatism mentioned is indeed as common as he supposes.[Z] The references in the literature are exceedingly meager on this point. In order to make a few tests at least, I undertook to examine nine horses with the aid of Dr. R. Simon, oculist, to whom I am greatly beholden for the assistance given in these and other tests to be mentioned presently. In not one of the nine cases did we discover anything like the curved deflection which is supposed to be the sign of the form of astigmatism in question. But in order to test objectively whether Berlin's assumption were justified, we examined in the laboratory fresh specimens taken from two horses. The eyes were fastened in a frame in what corresponded to their normal position. Their posterior spherical wall (i. e., their respective retinal surface) was replaced by a piece of ground glass. On a spherical surface linear movements of a point of light are always imaged as curves, no matter what the shape of the lens forming the image may be. (For a more detailed statement see page 170, at close of note.) Since, however, our investigation had to do only with those curves which were due to the qualities peculiar to the lens, we had to replace the spherical by a plane projection surface. In front of the eye thus modified a strong light was placed at such a distance that the image of it, produced on the improvised back of the eye by the cornea and the lens, was a sharply defined point of light. Now, when the source of light was moved, the point of light would also move on the glass plate. Sitting at some distance behind the eye, we observed the movements of this point through a telescope. Thus we became witnesses of what happens upon the horse's retina when a moving object passes in front of his eye. Although we saw the point of light move through relatively long distances both horizontally and vertically, no sort of deflection in its pathway could be noted. Berlin's exposition does not hold true for the eyes of the horses, either living or dead, which were examined by us.