be perceived in order to show their influence, thus proving the purely physical nature of that influence, for in a subject who was unable to see colors with one eye, the color stimulus had the same dynamogenic effect whether applied to the seeing or the defective eye. Increase of volume of blood in the limbs, measured by the plethysmograph, so far as we can rely on Féré’s experiments, ran parallel with the influence on muscular power, culminating with red, so that no metaphor is involved, Féré remarks, when we speak of red as a ‘warm’ color. On the insane the results attained by the use of colored glass do not seem to be quite coherent. Some of the earlier observers described the beneficial effects of blue glass in soothing maniacs. Pritchard Davies, however, was not able to find that red light had any beneficial effect, though on some cases blue had, while Roffegean found that, in the case of a somber and taciturn maniac who could rarely be persuaded to eat, three hours in a red-lighted room produced a markedly beneficial effect, and a man with 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.