460 FRANCIS B. SUMNER 



impaired. In both of these cases, it was the right eye*''^ which had 

 been destroyed, but I do not regard this fact as of any significance, 

 since in the third specimen thus treated there was Uttle or no 

 impairment of the pigment reactions. 



Since a very decided inhibition of these reactions was also 

 noticed in certain specimens which were injured in other ways, 

 without being bUnded (p. 465), it seems probable that the shock 

 of injury and not the loss of the sight of one eye was responsible 

 for such impairment of the chromatophore function as was ob- 

 served in these last cases. This, of course, is reason for suspecting 

 -a similar shock effect, perhaps an even greater one, in the case of 

 those fishes both of whose eyes had been destroyed. Certain facts 

 which I have recorded above may indeed be referred to this cause. 

 But it must not be forgotten that we have, quite apart from these 

 blinding experiments, conclusive evidence of the part played by 

 sight in these reactions. 



Relation between the degree of illumination and the shade assumed 



In discussing the experiments upon Rhomboidichthys, I pointed 

 out that the degree of illumination of the background had little 

 or no effect upon the reaction which the fish underwent. As a 

 special illustration of this principle, it was shown that a fish became 

 paler upon a white bottom, even though this was heavily shaded, 

 than upon a gray bottom exposed to a considerable measure of 

 light. The latter surface, in my experiments with Rhomboid- 

 ichthys, was shown photographically to be very much lighter than 

 the former. 



Identical results were obtained with Lophopsetta. One of the 

 boxes was painted gray of a shade close to no. 499 of Klincksieck 



^* I.e., the eye which belonged morphologically to the lower, unpigmented side 

 of the body. Pouchet (op. cit., p. 88) had just the opposite experience, finding 

 that one turbot whose left eye was destroyed failed to respond as well as previously, 

 though no such impairment was observed in a specimen whose right eye was de- 

 troyed. He suggested a possible physiological correlation between the left eye 

 and the skin of this (the upper) side. 



