No. 544] SHORTER ARTICLES AND DISCUSSION 247 



and 51 per cent, in the head color, has decidedly less pigment 

 than the lightest individual of either Scries B or Series C, with 

 77.5 per cent, black in the body color and 61 black in the head 

 color. 



The percentage differences in color between the series reared 

 in darkness and the two scries reared in light do not adequately 

 represent the color differences as perceived by the eye. The 

 average person probably would not hesitate to call the lighter 

 individuals of Series A '"white," and on the other hand would 

 probably class the various individuals of Series B and C as 

 •'dark gray" or "coal black." 



There appear to be no reasons for thinking that the marked 

 differences in pigment development were due to differences in 

 nutrition or differences in temperature. Series B so closely 

 resembled Series C in amount of pigment development that it 

 is evident the differences in temperature and food did not 

 greatly influence their pigmentation, yet Series B was reared in 

 a west room subject to great fluctuations in temperature because 

 of the extreme exposure to the summer sun during the afternoon, 

 and the temperature of this series on the average was probably 

 higher than in the outdoor pool in which Series C developed, 

 while the food was exclusively daphnids, copepods and bits of 

 beef. On the other hand Series A was maintained at a quite 

 uniform temperature consistently lower than either of the other 

 series. Fischel ('96) and Flemming (*J)7) found that with 

 certain salamander larvae (the former at least used larvae of 

 Salamandra metadata) temperature differences influenced the 

 amount of pigment development, the individuals reared at from 

 4° to 7° C. being much darker than individuals reared at from 

 15° to 20° C, indicating that for Salamandra maculata the lower 

 temperature favors greater pigment development. Inasmuch 

 as my lightest series. Series A, was reared at the lowest tempera- 

 ture of any and yet was markedly lighter than the others, and 

 that Series B and C did not differ widely in amount of pigment 

 development although reared under somewhat different tem- 

 perature conditions renders it improbable that temperature in- 

 fluences produced the differences in pigmentation observed. 



Series A and B were fed in every way alike and so far as 

 could be judged took about the same quantities of food. While 

 as a whole Series A developed less rapidly than Series B, part of 

 Series A developed more quickly than some of Series B yet each 

 individual possessed an amount of pigment similar to the others 

 of its series. Hence the evidence strongly points to the con- 



