Excerpt from Journal of Animal Behavior, 1916, Vol. 6 Finally the study Of the action currents Of the retina gives evidence Of differential sensitivity to wave-length in day birds, Kohlrausch and Brossa obtaining characteristic types of galvanometer deflection for different wave-lengths irrespective of intensity. The correlation between action currents and color vision has not been made however. All this evidence Offers good ground for the presumption of a true color vision in day birds, yet the results are in no case. Absolutely conclusive. The question of the nature Of the bird's spectrum, the number of primary colors, has not been approached experimentally. Hess describes the color vision of the fowl variously, as like that Of a normal man, and as like that of a man looking through a piece of orange glass. He takes the latter view because Of the supposed shortening Of the spectrum at the violet end. Watson's data upon the threshold of the fowl make this View untenable. Beyond the probability that the bird is capable of some sort Of reaction to wave - length, no definite conclusion can be drawn from the studies reviewed here. The details of spectral sensitivity, contrast, after images, color adaptation, and the r61e of color vision in the normal activities of birds are still Open problems, promising to tax Objective methods to the utmost. The present paper Offers further evidence for the existence of color vision in the fowl, in the form Of data upon the relative stimulating effect of different wave-lengths upon the light and dark adapted eye, the ability of the fowl to react upon the basis of wave-length, and the appearance of relatively abrupt changes in the stimulating value of different parts of the spectrum. The experiments were begun in 1912, but, owing to delays incident to reorganizing the apparatus and to pressure of other work, they have progressed but slowly. The chief problem and the method of attack I owe to the suggestion of Professor J. B. Watson who has also given generously of his time in the readjustment and control of the apparatus. 1 am indebted. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.