192 C. F. CURTIS RILEY 



but they usually remained at the side of the vessel nearest to 

 the window. On sunny days the writer often has observed that 

 young toads respond both to moving shadows and moving 

 objects. Sometimes they respond by crouching against the 

 ground, and at other times by the jumping response. The 

 response to moving objects has been noticed also on cloudy 

 days. The writer did not employ a heat screen during any of 

 these observations. Therefore there was no definite attempt to 

 isolate possible temperature responses from photic responses. 

 However, he infers from the experiments of Pearse (I.e., pp. 

 192-195) that these responses are probably not due to tempera- 

 ture. My observations were recorded in the middle of the 

 day, during the month of July. Similar responses occurring in 

 the early spring or late fall may be due largely to temperature. 

 Torelle (1903, p. 469) working with Rana virescens virescens 

 and Rana clamata noticed, in one series of experiments, that 

 specimens of both species responded positively to sunlight, but 

 that they did not stay in the circle of most intense illumination. 

 Some individuals moved away without turning. Others turned 

 and retreated some distance, and then oriented themselves with 

 their heads pointing toward the incoming beam of sunlight. In 

 another series of experiments in which specimens of the same 

 species of frogs were placed in a box, admitting sunlight at 

 one end and diffuse light at the other, Torelle (I.e., p. 471) found 

 that the animals "turned toward and moved to the end" where 

 the sunlight entered. They did not stay within the area of 

 strongest light, for they either moved to the opposite end of 

 the box, or else backed, without turning, into the region 

 where the light was less intense. These results correspond 

 more or less to my observations on young toads; although 

 unfortunately the present writer did not observe the kind of 

 response when the animals moved into the less illuminated 

 area. Dickerson (I.e., p. 71) has noticed the response of young 

 toads to sunlight. She states that, "They congregate in large 

 numbers on sunny brown earth patches." Such places are near 

 or among the grass. The observations of Miller (1909, pp. 659- 

 660) are in accord with those of Dickerson. The former has 

 noticed that toads are rarely seen during the day unless it is 

 cloudy. Late in the fall, however, they are found in the sun- 

 light, among the grass. It should be stated that none of these 



