a still closer bearing on the condition of primitive man, but here again the scanty evidence is negative. The only experimental investigation with which I am acquainted is that made by Romanes[1] on the chimpanzee 'Sally' in the Zoological Gardens. After having successfully taught this animal to recognize numbers, Romanes proceeded to apply a similar method to teach her colors, but wholly without success, and he was obliged to conclude that the animal was probably color-blind. It may be objected that the brilliant coloration of the mandrill and other species points to the existence of a color sense in the primates, but little weight can be attached to such indirect evidence in the absence of experimental investigation.
Another subject which has some bearing on the question is that of the color sense of the human child. It is now a more or less accepted principle in biology that the history of the individual presents the same stages of development as have occurred in the history of the race. Darwin[2] was the first to point out that the power of distinguishing colors is a very late accomplishment in childhood; he found that his children were unable to name colors correctly at an age in which they knew the names of all familiar objects. This subject has since been the subject of much investigation, the most important work having been done by the late Professor Preyer[3] and by Garbini.[4] Preyer made a very large number of investigations on one child, while Garbini has based his results upon the observations of no less than 600 children. Both agree in the conclusion that the child is unable to distinguish colors at all till towards the end of the second year, and they also agree that red is distinguished and named correctly at an earlier age than blue, although there is some difference of opinion as to the exact order of development of other colors. Garbini points out further that the power of distinguishing colors develops earlier than the power of naming colors, language appearing to lag behind sense. If any importance is to be attached to the bearing of the history of the child on the history of the race, the evidence from childhood is in favor of the view that the color sense of man is a comparatively recent acquirement.
Whatever room for difference of opinion there may be on the question of the evolution of the color sense, there can be no doubt that there has been an evolution of color language. The possibility that the course of this evolution has been determined by physiological conditions has been considered, but there can, I think, be little doubt that these have not been the only factors upon which the characteristic defects of language have depended. The deficiency in the sense for blue, which
