458 FRANCIS B. SUMNER 



use of a flash-light at night. In many cases the eyes moved un- 

 mistakably, or the fish even swam away, as a result of the stimulus. 

 Altogether, 16 specimens were deprived of the sight of both 

 eyes by cautery, while three others were blindfolded. Of this 

 total, 8 fishes were in the dark condition at the time of the blinding; 

 9 were in the pale condition, and two others in an intermediate 

 state. As regards results, the following general statements may 

 be made: 



1. Dark specimens, excepting those having the history speci- 

 fied below (3), remained dark after the destruction of sight. 



2. Pale specimens, after blinding, remained as pale as before 

 for about a day, after which they gradually grew darker, and be- 

 came indistinguishable from those which had been blinded when 

 in the dark state. The duration of this peristence of the pale 

 condition after blinding seemed to bear little relation to the length 

 of the previous sojourn upon a pale background. Thus fishes 

 which had been kept in white boxes for only two days before being 

 blinded retained the pale condition about as long as specimens 

 which had been thus kept for fourteen or seventeen days. 



3. Specimens which had passed considerable periods (seventeen 

 to twenty-five days) in a white or pale gray box, and then, before 

 blinding, returned to black just long enough to cause them to 

 resume the earlier dark shade (twenty-four hours, or less), became 

 pale again within a few hours after blinding, and remained thus for 

 about a day, after which they gradually became dark again. Three 

 of the four specimens thus treated reverted, after blinding, to 

 nearly or quite the maximum degree of pallor; the fourth became 

 distinctly paler, though not so pale as it had been. The results of 

 these experiments upon Lophopsetta are thus in complete agree- 

 ment with those obtained from the use of Rhomboidichthys and 

 Rhombus. On the other hand, with a single exception (see below), 

 none of the ordinary dark specimens became paler as the immedi- 

 ate result of blinding. 



4. The shade assumed by the blinded specimens was not there- 

 after influenced in any appreciable degree by the background.^'* 



** One apparent exception is to be recorded among all the specimens used. This 

 fish was of a fairly dark shade at the time of blinding. Some hours after transfer 



