ADAPTIVE CHANGES IN SHADES AND COLOR 

 OF FUNDULUS. 



C. J. CONNOLLY, 

 ZOOLOGICAL LABORATORY, HARVARD UNIVERSITY. 



CONTENTS. 



PAGE. 

 I. INTRODUCTION 56 



II. ADAPTIVE CHANGES IN SHADE 58 



III. ADAPTIVE CHANGES IN COLOR 61 



A. Effect of Colored Background 61 



B. Effect of Spectral Lights of Different Wave-lengths 64 



IV. THE BASIS OF ADAPTIVE CHANGES IN SHADE AND COLOR 67 



A . The Normal Coloration 67 



B. Shade Adapted to White, Gray, and Black Backgrounds 69 



C. Yellow Adapted 69 



D. Red Adapted Vaso-dilation 70 



E. Green Adapted 71 



F. Blue Adapted 71 



V. DISCUSSION 71 



VI. SUMMARY 74 



VII. BIBLIOGRAPHY 73 



I. INTRODUCTION. 



Considerable attention has been paid to the changes in shade and 

 color which fishes frequently undergo, and the significance of the 

 phenomenon. The subject is of some theoretical interest and 

 has given rise to a rather extensive literature, though the conclu- 

 sions arrived at by the various authors are far from unanimous. 



There are two important problems involved in these investiga- 

 tions, namely (i) whether fishes simulate the color of the environ- 

 ment and (2) whether they are able to discriminate light of differ- 

 ent wave-lengths. In other words, is the spectrum objectively 

 speaking the same for them as for a normal human being or do 

 they see the spectrum as a color blind person does a gray band 

 of varied intensity. If fishes simulate the background, this indi- 

 cates discrimination of wave-lengths or color vision, for it has 

 been established that the eye and not the skin as a whole acts as 

 the receptor of the light stimulus. It is, of course, here not im- 



56 



