. Comparative animal physiology. Physiology, Comparative; Physiology, Comparative. Chromatophores and Color Change 695 crab, Uca, which commonly contains black, red, yellow, and white pig- ments in the chromatophore system. After removal of the eyestalks from a member of any one of the three groups, the characteristic type of response for that particular group is ob- served. In Group I the animals darken rapidly through complete dispersion of their red and yellow pigment and become quite dark (although never as dark as in normal response to a black background) in an hour or two. They remain in
. Comparative animal physiology. Physiology, Comparative; Physiology, Comparative. Chromatophores and Color Change 695 crab, Uca, which commonly contains black, red, yellow, and white pig- ments in the chromatophore system. After removal of the eyestalks from a member of any one of the three groups, the characteristic type of response for that particular group is ob- served. In Group I the animals darken rapidly through complete dispersion of their red and yellow pigment and become quite dark (although never as dark as in normal response to a black background) in an hour or two. They remain in this condition indefinitely. The white pigment undergoes a transi- tory concentration and thereafter exhibits a variable state. Crago, of Group II, most commonly shows a more complex change after eyestalk removal. First there is a transitory darkening of the telson and uropods and a blanch- U. MLAtttOMtTtt GffOUPJl trtiTALKi Htuvfa Iter wHirt UAOt imirt mjlCTCO WITH tiHui-eumo tXTMCT %. o Fig. 262. Schematic representation of the coloration of eyestalkless crustaceans and state of the dominant chromatophores for each of the three differently responding groups, and of the responses of these to injection of eyestalk or sinus gland extract. Solid arrows indicate extract of total water-soluble material, dashed arrows indicate an alcohol-insoluble fraction, and dotted arrows indicate an alcohol-soluble fraction. From Brown, 1948. ing of the remainder of the body, which lasts from one half to one hour. This is followed by a complete blanching of the telson and uropods and darken- ing of the body to an intermediate and mottled coloration. The white pig- ment on the body initially concentrates but then assumes an intermediate condition. The crab, Uca, of Group III, blanches rather quickly after re- moval of its eyestalks, its black chromatophores becoming for the most part punctate, and its white ones commonly broadly reticulate. This condition is maintained without significant change
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