UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. II, No. 4, pp. 53-88, pi. 1 March 31, 1913 



THE CONTROL OF PIGMENT FORMATION 

 IN AMPHIBIAN LARVAE* 



BY 



MYRTLE E. JOHNSON 



CONTENTS 



PAGE 



A. Introduction 53 



B. Current theories of pigment formation 54 



C. The relation of amount of nutrition to pigmentation 59 



D. Effect of various kinds of foods upon pigmentation 64 



E. Effect of lecithin and various foods used in experimentation, upon 



the tyrosinase reaction 69 



F. Effect of lecithin upon pigmentation 73 



G. Effect of certain other organic substances upon the tyrosinase re- 



action and upon pigmentation 76 



H. Histological differences between chromatophores of larvae fed upon 



different foods 80 



I. Effect of changes in light, heat, and food upon pigmentation 82 



J. Summary 83 



K. Bibliography 84 



A. INTRODUCTION 



The experiments considered in this paper grew out of a series 

 of feeding experiments carried on with larvae of Hyla regilla 

 and Eana sp. While size differences only were considered at 

 first, color differences soon became so marked as to demand 

 attention. The amount of black pigment in the different lots of 

 tadpoles varied considerably and this variation was not correlated 

 with the size of the tadpole. It was apparent that certain foods 



* A thesis presented to the Faculty of the College of Natural Sciences, 

 in the University of California, in partial satisfaction of the requirements 

 for the degree of Doctor of Philosophy. April, 1912. 



