. Comparative animal physiology. Physiology, Comparative; Physiology, Comparative. 712 Comparative Animal Physiology responsive to certain environmental stimuli, changing reversibly through the spectral colors to red on excitation and in the opposite direction on recovery. This response is direct, and does not in\olve coordinating mechanisms within the animal, either nervous or humoral.^" Reptiles. The functional organization of the melanophores of reptiles shows, as in the fishes, a great diversity. It appears to involve, to differing degrees in different reptiles, the acti\'ities of hor
. Comparative animal physiology. Physiology, Comparative; Physiology, Comparative. 712 Comparative Animal Physiology responsive to certain environmental stimuli, changing reversibly through the spectral colors to red on excitation and in the opposite direction on recovery. This response is direct, and does not in\olve coordinating mechanisms within the animal, either nervous or humoral.^" Reptiles. The functional organization of the melanophores of reptiles shows, as in the fishes, a great diversity. It appears to involve, to differing degrees in different reptiles, the acti\'ities of hormones and nerves. The melanophore responses of the iguanid, Anolis, have been iuACsti- gated very extensively by Kleinholz.'''^ These lizards show color changes ranging from bright green to dark brown. They typically assume the former color in an illuminated white container, and the latter in an illuminated black one. The response to change from a white to a black background is. Fig. 274. A normal dark and a hypophysectomized light Anolis. From ;" usually completed in 5 to 10 minutes. The reverse change normally re- quires 20 to 30 These background-induced responses depend on the eyes; they cease after bilateral blinding. However, such blinded speci- mens still are capable of color change; they darken in light and become pale in darkness, through primary responses. For many years after Briicke's-*'' classical studies of color change in the chameleon, in which he demonstrated nervous control of the melanophores by the sympathetic system, it was considered that reptilian chromatophores generally were thus controlled. Studies on Phrynosoma,^''^ however, pro- vided basis for a strong suspicion that nerx'es were not the sole method of control. The lizard, Hemidactylus, becomes pale in color after hypophysect-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appea
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