522 A. B. DAWSON 
C. Effects of temperature 
1. In other Amphibia. The melanophores of various Amphibia 
have been shown to be affected by changes in temperature. 
Usually high temperatures cause a contraction of the pigment 
cells, while low temperatures favor an expansion. Most of the 
experiments with temperatures have been carried out in con- 
nection with light. 
Early observers noted that frogs almost invariably become 
dark when kept at low temperatures (von Wittich, ’54; Hering 
und Hoyer, ’69; Knauthe, ’91; Biedermann, ’92; Ehrmann, ’92 b). 
For Salamandra maculosa, Fischel (96) found that the temper- 
ature to which the animals were subjected was an important 
factor. He observed that larvae which developed in warm water 
were light and that if dark-colored larvae were placed in warm 
water they became pale. Flemming (’97 a) thought that light 
alone was the cause of the color changes, but later (’97 b) dis- 
covered that temperature also affected the coloration of sala- 
manders. He obtained maximum contraction of the melano- 
phores by placing larvae in the light in a white dish containing 
water warmed to 24°C. <A low temperature, however, inhibits 
the effects of the background and illumination, leaving the 
chromatophores partially expanded. Rogers (’06) found that 
a low temperature causes Diemyctylus to become dark, while a 
high temperature has an opposite effect. In this animal light 
also brings about a contraction of the melanophores and darkness 
an expansion. The response to light is less pronounced than 
that obtained by a change in temperature and may be obscured 
by the latter factor. When a combination of high temperature 
(35° to 40°C.) and darkness is made, or when a low temperature 
(10°C.) is combined with bright light, no response is obtained 
and an ‘ordinary’ coloration results. 
Hargitt (12) found that, while a high temperature brought 
about a lightening of the coloration of tree-frogs, no definite 
effect was produced by a low temperature. Laurens (’15) 
’ observed that low temperature caused the melanophores of 
Amblystoma larvae to expand, high temperatures (above 38°C.) 
