1913] Johnson: Pigment Formation in Amphibian Larvae 75 



TABLE 8 



Length measurements of Hyla tadpoles fed on liver and liver plus lecithin. 

 Length measurement represents average length of all the tadpoles. 

 Six tadpoles in each lot. 



Eyla. 1912 



Length in mm. 



Food Mar. 5 Mar. 14 



Liver 19.5 24.4 



Liver + lecithin 19.6 26.2 



Mar. 14. Tadpoles fed on liver plus lecithin are lightest have a greenish 



tinge while others are black. 

 Mar. 25. Tadpoles fed on liver are all dead. 



Two sets of Hyla tadpoles were fed on egg yolk and egg yolk 

 plus lecithin (table 9) : 



TABLE 9 



Length measurements of tadpoles fed on yolk and yolk plus lecithin. 

 Length measurements represent average length of all the tadpoles. 

 Eight tadpoles in each lot. 



Hyla. 1912 



Length in mm. 



Food Mar. 5 Mar. 14 Mar. 25 



Yolk 15.7 18.2 22.6 



Yolk + lecithin 15.6 17.6 22.1 



Mar. 14. Sizes are uneven. No marked color differences. A few lighter 

 individuals among the tadpoles fed on yolk. 



Apr. 1. Tadpoles fed on yolk average slightly darker than the others 



pigmentation very uneven. 

 (Tadpoles accidentally mixed, experiment discontinued.) 



The experiments plainly show that lecithin lightens the color 

 of the tadpoles. It is not clear that lecithin plus yolk of egg 

 produces lighter colored tadpoles than yolk alone does. It would 

 appear that for tadpoles of the size reached by these at least, 

 additional amounts of lecithin do not lighten the tadpoles 

 noticeably. 



Miss King (1907) has suggested that the tadpoles that are 

 fed with lecithin are not so thrifty as the others. Although there 

 has been a slightly larger percentage of deaths among the tad- 



