. Biology in America. Biology. 226 Biology in America to the time of the fall molt the birds were put in a darkened room and their food supply slightly increased. On this regi- men the birds grew fat and lazy and ceased to sing. Most of them passed the winter thus in full summer plumage, but one of the tanagers molted into the winter plumage as a result of a siidden change of temperature. In the spring the birds were brought under normal conditions again and promptly molted into the spring plumage, the winter molt having been entirely suppressed, a beautiful example of environmental control of
. Biology in America. Biology. 226 Biology in America to the time of the fall molt the birds were put in a darkened room and their food supply slightly increased. On this regi- men the birds grew fat and lazy and ceased to sing. Most of them passed the winter thus in full summer plumage, but one of the tanagers molted into the winter plumage as a result of a siidden change of temperature. In the spring the birds were brought under normal conditions again and promptly molted into the spring plumage, the winter molt having been entirely suppressed, a beautiful example of environmental control of an hereditary The Scarlet Tanager, Male and Female (Right) A striking example of sexual difference in birds. The winter dress of the male is similar to that of the female. From Cooke, "Bird Migration," in Bulletin Bureau Biological Survey. The Bobolink (Left) A bird of many aliases, admired in the North, detested in the South. From a drawing liy Louis Agassiz Fuertes in Cooke, "Bird Migration," Bulletin Bureau Biological Survey. The effects of light on the color of animals are clearly marked in some instances, and in others seemingly negligible. The typical fauna of caves comprises animals, which have little or no pigment, and either partly or wholly degenerate eyes. The amphipod Eucrangonyx gracilis occurs both in the open and in caves. In the latter situation its eyes alone are pigmented, while in the former, other parts of the body. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Young, R. T. (Robert Thompson), b. 1874. Boston, R. G. Badger
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