delusions of persecution became quite rational and was even in a condition to be sent home after a few days in the same room. He also found that a violent maniac wearing a strait jacket, after a few hours in a room with blue glass windows became quite calm and gave no further trouble. Osburne has found, after many years' experience, that in the absence of structural disease violet light (for from three to six hours) is most useful in the treatment of excitement, sleeplessness and acute mania; red he has found of some benefit, though to a much less degree in such cases (it must be remarked that violet light as usually applied is not free from red), while he has not found any color with which he has tried experiments (red, orange or violet) of benefit in melancholia. The significance of these facts is not altogether clear; the influence, as Pritchard Davies concluded, seems to be largely moral, though it may be that the colors of long wave-length are tonic and those of short wave-length sedative.
So far I have been chiefly concerned to point out that the immense emotional impressiveness of red has a basis in physical laws, being by no means altogether a matter of environmental associations. It is true that the two groups of influences overlap, and that we can not always distinguish them. We can not be sure that the greater sensitiveness to the red rays may not have been emphasized in the organism, not necessarily as the result of inherited acquirement, but probably as the perpetuation of a variation of sensibility, found beneficial in an environment where red was liable to be especially associated with objects that were to be avoided as terrible or sought as useful. In this way the physical and environmental factors would run in a circle.
We have to bear this consideration in mind when we take into account the susceptibilities of animals, especially of the higher animals, to red. The color sense, it is well known, is widely diffused among animals; indeed this fact has been brought forward, especially by Pouchet, to prove that there can have been no color evolution in man; this it can scarcely be said to show, since evolution does not run in a straight line, and it is quite conceivable and even probable that the ancestors of man were less dependent than many lower animals, for the means of living, on a highly developed color sense. Thus a color sense that among some creatures is so highly developed as to include even the ultra-violet rays, was among our own ape-like ancestors either never developed or partially lost.
Graber, in his important investigation into the color sense of animals, showed that of fifty animals studied by him forty showed strong color preferences in their places of abode. In general he found, without being able to explain the fact, that animals which prefer the dark are red lovers, those which prefer the light are blue lovers. The common worm, with head and tail cut off, still preferred red to blue nearly as