American Fisheries Society 241 



time, but reverted to a dark condition, representing more 

 nearly the resting state of the chromatophores. An interest- 

 ing special case, in which fishes turned pale immediately 

 after blinding, will be shown in the lantern views.* De- 

 struction of one eye commonly had little effect or none 

 upon the power of adaptive color change. Indeed, one of 

 the specimens which changed most rapidly and completely 

 had been deprived of one eye. Tactile stimuli, if effective 

 at all, are certainly quite subordinate, for the fish re- 

 sponded as promptly to patterns painted upon the under 

 side of a sheet of glass as to bottoms of stones and gravel, 

 whose complexity could be discerned by touch as well as 

 sight. 



(2) In the case of Rhomb oidichthys the underlying 

 surface appears to be the one chiefly effective in calling forth 

 these changes. The vertical walls of the jar, when the lat- 

 ter were opaque, seemed to exert a subordinate influence, 

 though I have pretty conclusive evidence that this influence 

 was at times effective. What the fish saw directly overhead 

 seemed, on the contrary, to exert a negligible influence upon 

 the color pattern. (Experiment with spotted plate over- 

 head. ) 



(3) In the case of our local sand-dab {Lophopsetta 

 maculata) — a species related to Rhomb oidichthys — the 

 vertical walls of the receptacle exert a very pronounced 

 effect, at least the lower portion of these walls, which is 

 nearest to the eyes of the fish. I have performed experi- 

 ments which seem to indicate that, with this fish at least, it 

 is the total quantity of black and white surface seen — irre- 

 spective of whether vertical or horizontal — which deter- 

 mines whether the fish shall be dark or light. 



(4) Finally, within very wide limits, the degree of 

 illumination of the background has little or no effect upon 



* These were fishes which had been kept for a considerable period 

 upon a white background, after which they had been returned to a 

 dark background just long enough to cause them to become dark 

 again. 



