ADAPTIVE CHANGES IN COLOR OF FUNDULUS. 



73 



simply comparing the different colored lights and no valid con- 

 clusions can be drawn from tests of this kind. 



In his food association experiments, Ohashi noted that fishes 

 could not discriminate red when this color was plainly visible to 

 the human eye. This does not disprove color discrimination in 

 fishes for it is quite probable that at a lowered intensity they 

 :mabl<- t'i discriminate color and yet be able to do so 

 above a certain threshold of intensity. Hess, in fact, has shown 

 that the red end of the spectrum is shortened for fishes. 



\Yhen subjected to prolonged stimulation by red and by violet 

 li^'l ame reddish yellow and bluish and on examina- 



tion it was fiiund that the melanophores expanded in blue light 

 and the xantl es in yellow light. Unless, therefore, there 



is a direct ctTcct .t on the chromatophores as Secerov 



claimed, but whi> Frisch and Mast deny, the reported adap- 



tive cnlnratiiiii mu>t be due to color discrimination. 



Ohashi next placed fishes on eight bottoms of colored paper; 

 blue (two tints), red (also two tints) white, black, and gray (two 

 shade- 1. ('bailees in color were noted in 30 seconds and com- 

 pleted in t\v minutes, the principle colors noted being dark, red- 

 dish \elli.w and blue. If we have here a case of adaptive colora- 

 tion, it wi'iild ie a remarkable rapidity in the response. Ob- 

 ;i>l\ it is ciily adaptation in shade, as the author finally con- 

 :ed when all specimens were compared with one another and 

 it was noted that those which had been on a dark red bottom were 

 similar in >h.ide to those on a grey. The period was entirely too 

 -hort. hov conclude from this experiment that they are 

 uuabl' the background in color. 



The sank' may be said regarding his final experiments where 

 fi-hes were >ubiec;ed to the stimulus of red and blue from filters, 

 those in the red becoming reddish yellow and those in the blue, 

 dark within five minutes. When the blue light was made more 

 intense than the red, the fishes in the blue light became yellow 

 and those in the red dark. Again intensity of light was no doubt 

 the factor cau>iug different degrees of contraction of the 

 nielanoiihorcs as the author concludes and as we have noted for 

 F;tudn!us. This however, does not disprove color discrimination 

 for these species. On the contrary, the results following pro- 



