398 WILLIAM L. DOLLEY, JR. 



blackened were placed in the center of the enclosure, specimens 

 of some species went uniformly in circles toward the uncovered 

 eye, while those of other species, among them Vanessa antiopa, 

 moved continuously toward the blinded eye, although all were 

 positive. Since insects which are positive in their reactions to 

 light usually go in circles toward the uncovered eye, when one 

 eye is blackened, while those which are negative go in circles 

 toward the blackened eye, the above results were apparently 

 inexplicable. Since, however, Vanessa antiopa, which is highly 

 positive, goes in darkness in circles toward the blinded eye, it 

 is clear that the results secured by Holmes and McGraw are to 

 be explained by the fact that at times the stimulus exerted by the 

 covering of the eye was strong enough to overcome the stimulus 

 exerted by light on the uncovered eye. When the butterflies went 

 toward the functioning eye, they were responding to light, while 

 when they went in circles toward the blinded eye they were re- 

 sponding to the stimulus exerted by the covering of the blackened 

 eye. 



The above statement probably applies equally well to the 

 peculiar results which Brundin obtained. These are described 

 in the following manner ('13). 



"In positive specimens of Orchestia traskiana, circus move- 

 ments will occur as often toward the blackened eye as toward 

 the normal eye. All specimens used for this experiment were 

 strongly positive. There is no way to account for this varia- 

 bility, except that the animal might be made temporarily nega- 

 tive by having one of the eyes covered over. The fact, however, 

 that as soon as the blackening is removed from the eye of one 

 of these 'apparently negative' specimens, its reactions to the 

 light is decidedly positive, seems to throw considerable doubt 

 upon this hypothesis." 



It seems very probable that the circus movements toward the 

 blackened eye performed by this amphipod were due to a stimulus 

 produced by the covering of the blinded eye and were not due 

 to light. 



It is possible, also, that the above described behavior in dark- 

 ness of Vanessa may be suggestive in connection with the peculiar 



