Some experiments on newts, made by myself several years ago, show that the absence of light does not influence pigmentation,--that is, through several generations. My animals were kept under observation from the extrusion of the eggs until full maturity had been reached, and great care was taken to make experiments as accurate and as conclusive as possible. Those reared in total darkness or in a red light were always dark-colored; those reared in a yellow light[96] were almost but not quite as dark; while those reared in white ironstone crocks and in diffused daylight were very much lighter, being pearl-gray in color. This apparent (for the microscope showed that it was only apparent) absence of color in the last-mentioned specimens was due to tinctumutation. [96] Vide Dewar, "The Physiological Action of Light," _Nature_, p. 433, 1877; quoted also by Semper, _loc. cit. ante_, Notes, p. 423. I do not think that the absence of the slight amount of color in the animals reared under the yellow light was due to the "optic current" of Dewar. The microscope showed that the chromatophores were just as large and just as numerous, and that they contained as much pigment, as those reared under the red light. The apparent absence of color was due to tinctumutation.--W. In most viviparous animals the embryo is developed in almost or absolutely total darkness, yet when it is born it has bright colors. Kerbert has found in the cutis of the embryonic chick, about the fifteenth day, certain pigment-cells. These cells have entirely disappeared by the twenty-third day. It is probable that little, if any, light can reach the chick through the shell and membranes, yet pigment-cells develop and disappear again.[97] [97] Karl Semper, _Animal Life_, p. 422.