1913] Johnson: Pigment Formation in Amphibian Larvae 61 



TABLE 1 



Length measurements and color of tadpoles fed on different amounts of 

 food. Tadpoles of lots A and B were all the same size when the experi- 

 ment began Feb. 10, 1912; those of C and D were the same size 

 when the experiment began, April 28, 1911. Length measurements for 

 lots A and B represent average length of all tadpoles in the dish, those 

 for C and D, the average of several typical tadpoles. 



Amount 



of 

 food 



Full amount 

 % full amount 

 y 2 full amount 



A. Eana tadpoles fed on liver 

 Length in mm. 



Feb. 13 

 16.1 

 15.4 

 15.6 



Feb. 20 

 21.4 

 20.2 

 19.1 



Mar. 6 

 27.4 

 24.0 

 22.5 



Number 



of 

 tadpoles 



Color 

 Dark 

 Dark 

 Dark 



B. Eana tadpoles fed on egg yolk 



Amount 



of 

 food 



Full amount 

 % full amount 

 1/ full amount 



Amount 



of 

 food 



Full amount 

 % full amount 

 y 2 full amount 



C. Hyla tadpoles fed on liver 



Length in mm. 



May 10 

 16 

 13 

 12 



June 3 

 30 

 23 

 20 



Number 



of 

 tadpoles 



Color 

 Dark 

 Dark 

 Dark 



Amount 



of 

 food 



Full amount 

 % full amount 

 y 2 full amount 



D. Hyla tadpoles fed on egg yolk 



Owing to accidents and the small allowance of food, most of 

 the tadpoles living on half the regular fare died before meta- 

 morphosing. I have one preserved specimen, however, which is 

 about half the normal size and hardly more than skin and bones, 

 but is as deeply pigmented as any of the larger specimens. 



Tornier's experiments with yolk removal were also imitated 

 with the Hyla and Eana tadpoles. Here again it was found that 

 the tadpoles which had lost yolk, though smaller than the others, 



