CONTENTS 



1. Introduction 5 



The conditions of the experiment 7 



2. Alterations in the pigmentary system 10 



The chromatophores of the albinous larvae 14 



The epidermal melanophores 14 



The deep melanophores 18 



The xantholeucophores IS 



Epidermal transplants 23 



The effect of various diets upon the pigment cells 27 



The respoiises of the chromatophores to various physiological and phar- 

 macological agents 30 



3. Growth disturbances 41 



The growth rate of the albino; the effect of the administration of various 



physiological substances upon this growth rate 44 



The growth rate of thyroidectomized larvae 67 



4. Modifications in the size and structure of the endocrine organs 68 



The hypophysial components 69 



The thyroid 83 



The adrenal cortex and medulla 90 



The epithelial bodies 97 



The fat-organ 99 



5. Discussion 100 



6. Summary 103 



Bibliography 109 



