While we must reject the explanation based on suggestion,[AC] we believe, on the other hand, that we have here again, evidence of the presence of visual signs, given unwittingly and involuntarily, just as I am sure that they were involved in the two preceding cases, and similarly in the case of the Huggins dog. Since the effective signs were discoverable in none of these canine predecessors of Hans, an investigation would be desirable, based upon the insight gained as a result of these experiments upon Mr. von Osten's horse. Unfortunately this is impossible, since the dogs in question are dead. But others like them undoubtedly exist in many places. We might mention that when Hans first came under the limelight of public attention, there was also frequent reference to the Huggins dog, but he soon dropped out of the discussion again.[63] And this for two reasons. The dog never took his gaze from his master and appeared to be entirely dependent upon him in his reactions. Hans, on the other hand, seemed to give evidence of a high degree of independence and never appeared to look at the questioner. But we know now that, though he was never dependent upon the will of his master, he, too, abjectly hung upon the man's involuntary movements and never for a moment lost him from view. But since the horse is able to observe with one eye alone, and needed to direct only it and not the entire head toward the questioner, in order to focus comfortably, one could not conclude as to his line of vision from the direction of the head. Since, furthermore, in the horse the pupil is hardly distinguishable from the darkly pigmented iris and since the white sclerotic is hidden by the eyelids, except when the eye is turned very much, it is difficult to determine what direction the eye is taking. I once purposely stepped backward to the horse's flank, so that he had to turn his eye far back and thus the outer border of the iris and the white sclerotic coat became visible and all doubt concerning the line of vision was removed. This doubt could never arise in the case of the dog, the median plane of whose head is always directed toward the object fixated, and Zborzill is justified in saying, as he does, in his discussion of training of the kind mentioned on page 177, "But any careful observer can immediately guess the manner in which such a dog has been trained."[64] If Hans had chanced to possess so-called "glass-eyes"--in which the dark pigment is wholly or partly lacking, so that the black pupil is clearly defined against the lighter background,--then no doubt could ever have arisen concerning the direction of the eye, and Hans never would have come to be regarded as the "clever" Hans.