PEARSE. 



THE REACTIONS OF AMPHIBIANS TO LIGHT. 



173 



twenty reactions were, as a rule, recorded from an individual on any 

 one day. As the method of procedure was the same in all cases, and, 

 as the only object in view was to compare the reactions of eyeless and 

 normal animals, the discussion under each species will be limited 

 mostly to the results obtained. 



(c) Amblystoma punctatum. 



Four individuals were used in the experiments upon this species. 

 After the eyes had been excised, the two smaller animals, which 

 measured about seven centimeters in length, did not survive more 

 than a day or two. The two adult individuals, however, were ap- 

 parently little affected by the operation, and one of them lived for 

 forty-seven days after it. The results of the experiments are given 

 in Table I. This species is shown to be negatively phototropic, both 



TABLE I. 2 



Photic Reactions of Amblystoma punctatum, with and 

 without Eyes. 



in the normal and eyeless condition. As might be expected, there were 

 more movements without reference to the light after the eyes had been 

 excised, but this may have been due to the effects of the operation. 

 Whether this is true or not, the fact remains that the animals were 

 able to respond negatively to light received through the skin. 



(d) Plethodon cinereus erythronotus. 



This species manifested the same negative phototropism as the last, 

 when in normal condition, but it did not stand the operations well. 



2 In the tables which appear throughout this paper the following signs 

 are used: " + " indicates a decided movement toward the light, " — " is 

 used for a similar movement away from the light, and "0 " signifies that the 

 individual remained still for fifteen minutes or made a movement without 

 apparent reference to the light. 



