COLOR CHANGES AND ADAPTATION IN FISHES. 229 



Concerning the details of the processes involved nothing is yet known. Driesch, 

 however, would probably hold that it can not be explained on purely mechanical 

 grounds. It is well known that in man the image of an object may result in the same 

 sensations, no matter from what angle the object is viewed. Thus a dog seen from 

 the side may cause the same sensation as one seen from in front or from any other 

 point of view, although the image on the retina in each case differs greatly from that 

 in any other case. This phenomenon is like that just discussed in fishes. Driesch 

 holds that in man it can not be explained on a purely mechanical basis. We should 

 consequently expect him to maintain the same view for the phenomenon in fishes. 



