270 



bulletin: museum of comparative zoology. 



in such a way that the eyes were completely covered. These hoods 

 were attached by two threads to a light copper wire, which encircled 

 the animals' bodies just back of the fore-legs. To insure that no 

 light penetrated these hoods, they were blackened inside and out 

 with India ink. The extreme tip of the hood was cut off so that respi- 

 ration should not be interfered with. 



The hoods were at first a source of some irritation to the toads, 

 which struggled more or less to get rid of them. In a day or two, how- 

 ever, the toads showed no inconvenience when the hood was slipped on, 

 but remained quietly seated on the bottom of the battery-jars in 

 which they were kept (p. 263). In testing the reactions, the methods 

 and procedure of the experiments were the same as described on p. 

 264-266. 



The results of these tests are given in Table 3. Four sets of twelve 

 toads each were tested, the total number of trials for each light being, 

 therefore, 384. For the first two sets, six of the twelve toads were the 

 same as had been used in the first two sets of experiments in which the 

 eye and skin acted as receptors, and in the three sets of experiments 



TABLE 3. 

 Reactions of toads to monochromatic light received through the skin only. 



The numbers under + indicate total numbers of reactions toward the light; 

 under — , away from the light; under ±, without reference to the light (indifferent); 

 under 0, no reaction within five minutes. 



in which the eye acted as the receptor; the other six were toads which 

 were supplied to take the place of six that had died during the course 

 of the experiments. For the last two sets, two new lots of twelve 



