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University of California Publications in Zoology [Vol. 11 



Table 3 



Length measurements and color of tadpoles fed on different kinds of food. 

 Measurements represent average of several typical tadpoles from each 

 dish. 



A. Hyla. Experiment started Feb. IS, 1911 



To see if it would be possible to lighten the color of tadpoles 

 that were already strongly pigmented, some very dark tadpoles 

 collected from a pond were fed upon yolk of egg. In nine days 

 they were distinctly lighter than tadpoles from the same source 

 that had been kept in the aquarium on a mixed diet. I do not 

 regard this as a disappearance of pigment already present in 

 the tadpole, but rather as a decrease in pigment production 

 relative to growth. The proportion of pigment formed is less 

 with egg yolk as food, so that the ratio of pigment to body size 

 decreases, until within nine days, the difference in color is 

 noticeable. 



If we assume an oxidase reaction as the basis of pigment 

 formation in the tadpoles we explain a decrease in the rate of 



