CONTRIBUTIONS FHOM THE ZOOLOGICAL LABORATORY OP THE MUSEUM OF COMPARATIVE ZOOLOGY AT 



HARVARD COLLEGE, NO. 212 



THE PHYSIOLOGY OF THE CHROMATOPHORES OF 



FISHES 



R. A. SPAETH 



THREE TEXT FIGURES AND FOUR PLATES 



CONTENTS 



1. Preliminary 



1 . Introduction 527 



2. Material 528 



3. Methods 530 



2. Reactions to salt solutions and distilled water 



1. Effects of sea-water and distilled water 533 



2. Effects of single electrolytes 543 



a. Potassium salts 543 



b. Sodium salts 547 



c. Comparative effects of the alkaline chlorides 550 



d. Comparative effects of magnesium chloride and sulphate 552 



3. Effects of mixed electrolytes 553 



3. Pressure effects 558 



4. Temperature effects 560 



5. Reactions to oxygen 563 



6. Light effects 565 



7. Electrical effects 569 



8. Conclusion and summarj^ 570 



9. Bibliography 577 



1. PRELIMINARY 

 1. Introduction 



In the great majority of researches upon the physiology of the 

 color-changes in vertebrates, the experiments have been made 

 upon Hving animals. In such cases the experimental condi- 

 tions have necessarily been complicated by a central nervous 

 inhibition, abnormal circulation, oxygen supply, etc. A direct 

 response of the chromatophores has been claimed by many inves- 



527 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 15, NO. 4 



