84 University of California Publications in Zoology [VOL. 11 



The present research is by no means complete, the results so 

 far attained suggesting numerous very pertinent points that 

 should be investigated farther. It does, however, furnish certain 

 definite facts which it is hoped will add something to current 

 conceptions of color differentiation. 



The research shows that pigment in Rana and Hyla tadpoles 

 is not correlated with amount of nutrition, as claimed by Tornier 

 for Pelobates larvae, but, as suggested by instances cited by 

 Darwin and Wallace, is dependent rather upon substances 

 specific for color in the nutritive material. These substances may 

 bring about a change in the amount of pigment-forming sub- 

 stances produced or slightly alter the character or combination 

 of these substances and thus change the amount or color of the 

 pigment. 



The fact is made clear that lecithin acts as a partial inhibitor 

 of the tyrosinase reaction in the test tube, and when it is fed 

 to tadpoles, pigment formation is checked to a noticeable degree, 

 indicating that inhibitors or modifiers of the pigment formation 

 may be introduced into the organism with the food. 



The similarity of the effect of lecithin in the test tube and in 

 the body of the tadpole makes it probable that the tyrosinase 

 reaction or a similar oxidase reaction is the basis of pigment 

 formation in the tadpole. 



BIBLIOGRAPHY 



ABDERHALDEN, E., AND GUGGENHEIM, M. 



1907. Versuche iiber die Wirkung der Tyrosinase aus Eussula delica 

 auf Tyrosin, tyrosinhaltige Polypeptide und einige andere 

 Verbindungen unter verschiedenen Bedingungen. Zeit. f. 

 physiol. Chem., 54, 331-353. 

 ABDERHALDEN, E., AND HUNTER, A. 



1906. Hydrolyse des im Eigelb des Hiihnereies enthaltenen Proteins 



("Vitellin"). Zeit. physiol. Chem., 48, 505-512. 

 ABDERHALDEN, E., AND PREGL, F. 



1905. Die Monoaminosauren des krystallisierten Eieralbumins. Zeit. 



physiol. Cheni., 46, 24-30. 

 ABDERHALDEN, E., AND SAMUELY, F. 



1905. Die Zusammensetzung des "Gliadins" des Weizenmehles. 

 Zeit. physiol. Chem., 44, 276-283. 



