ADJUSTMENT OF FLATFISHES 459 



Change from all-black to all-white boxes called forth no visible 

 response. 



5. Whatever the original shade of the fish, that which was 

 finally assumed was, as already stated, a dark one. But the final 

 condition was not, in the majoritj^of cases, that of maximum dark- 

 ness. It was frequently a shade distinctly paler than this, though 

 in all cases one nearer to the darkest than the palest condition. 

 Certain blinded specimens displayed a distinctly abnormal appear- 

 ance which I never observed in an uninjured fish. On the other 

 hand, some specimens remained very dark, and of normal appear- 

 ance, to the end. For example, one fish (pale when blinded) was 

 of about the maximum degree of darkness, even after forty-one 

 days.**^ 



With six specimens, the sight of one eye only was destroyed. 

 In three cases, this was the right eye, in three others the left. 

 Since the two eyes are rather differently directed with reference 

 to the bottom, I thought it worth while to look for a possible differ- 

 ence in the effect of the two operations. Of these six specimens, 

 four retained the power of adaptive change nearly or quite unim- 

 paired. Indeed one of these, for rapidity and completeness of 

 the adjustment, remained one of the most favorable specimens 

 which I encountered. 



Of the two remaining fishes, one appeared to have very largely 

 lost the power of change while in the other, this was considerably 



to a white receptacle, the animal was found to be very pale. It must be borne in 

 mind, however, that the immediate result of cauterizing the eyes was not complete 

 blindness, but that the corneas were merely rendered opaque. In this exceptional 

 specimen the opacity might not have been complete. 



• '^ According to Pouchet, the shade assumed by a blinded turbot was always an 

 intermediate one. Mayerhofer, experimenting upon pike, found that theimmediate 

 effect of blinding was a paling of the fish, this being followed by the assumption of 

 a more intensely colored condition than before the operation, accompanied by a 

 disappearance of the dark bands. The further history of the specimen depended 

 upon whether it was kept in the dark or in the light. If the former, the pigment 

 tended to disappear. If the latter, the pigment cells not only persisted on the 

 back and sides, but developed upon the (normally pale) ventral surface. This 

 last phenomenon suggests the artificial production of pigment upon the lower side 

 of flounders in Cunningham's well-known experiments. 



