. The biology of the amphibia. Amphibians. 148 THE BIOLOGY OF THE AMPHIBIA supply. The striped pattern of many adult salamanders may be considered a retention of the early larval pattern. In frogs a somewhat similar pattern may first appear at metamorphosis, but whether or not it is correlated with regions of active skin growth has not been determined. The pigmented sides of many salamander larvae bear three rows of light spots. In the center of each is usually located a lateral-line sense organ (Fig. 57). In many plethodontid larvae the light area is devoid of pigment, but in certain salamand
. The biology of the amphibia. Amphibians. 148 THE BIOLOGY OF THE AMPHIBIA supply. The striped pattern of many adult salamanders may be considered a retention of the early larval pattern. In frogs a somewhat similar pattern may first appear at metamorphosis, but whether or not it is correlated with regions of active skin growth has not been determined. The pigmented sides of many salamander larvae bear three rows of light spots. In the center of each is usually located a lateral-line sense organ (Fig. 57). In many plethodontid larvae the light area is devoid of pigment, but in certain salamandrids lipophores may be clustered in these areas. In some adult. Fig. 57.—Larva of the two-lined salamander, Eurycea bislineata, showing the relation of the color pattern to the lateral-line organs. Each small ring within the light areas represents a lateral-line organ. salamanders which retain the lateral-line organs, guanophores may come to occupy the same position. Thus, the lateral-line organs frequently have an effect on controlling the color pattern, since melanophores fail to develop near them (Noble, 1927). Whatever might be the causes of melanophore localization, it may be noted that melanin is often produced in regions of high metabolism. The more active hemisphere of frogs eggs is usually pigmented, although when eggs contain much yolk they may be devoid of pigmentation. Faris (1924) found that pigment was produced in the embryo of Ambystoma in regions of rapid dif- ferentiation rather than of cell proliferation. Melanin is pro- duced by the oxidation of tyrosin or similar chromogen base, which is presumably, as in the case of the former, a product of protein metabolism. The transformation is produced under the influence of a tyrosinase or similar oxidizing ferment. A tyro- sinase has been described in the skin of various Amphibia (Ges- sard, 1904) as well as in the frog's egg. Banta and Gortner (1913) found that dilute solutions of tyrosin produced a darkening of t
Size: 3814px × 655px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookpublishernewyorkmcgr, booksubjectamphibians
