RESPONSES OF YOUNG TOADS 191 



many of these cross lights are cut out as the rays enter the 

 dark room, yet it would be incorrect to state that all the rays 

 of light are parallel with each other and with the median longi- 

 tudinal axis of the bodies of the toads facing the light. 



Graber (I.e., pp. 120, 121) while making observations on 

 Rana esculenta L., stimulated by means of weak diffuse day- 

 light, "meist truber Himmel," states results which lead to the 

 inference that these animals react negatively to photic stimuli 

 of such a nature. However, their responses were not so pre- 

 ponderantly negative as was the case of Bufo vulgaris Laur 

 already mentioned. The following quotation will give an idea 

 of his results (I.e., p. 121): 



"Auch zeigt der Versuch, dass das Reactions- Verhaltnis ein sehr con- 



stantes ist, indem die Weiss-Frequenz sich zwischen 11 und 18 und die 



des Schwarz zwischen 22 und 29 bewegt, und grossere Extreme, wie 



solche sonst sehr haufig sind, mit Ausnahme eines einzigen Falles (7:33) 



gar nicht vorkamen. 



"Das Mittel- Verhaltnis ist: 



Weiss 1 

 1) = .» 



Schwarz 1 . 5 



Loeb (I.e., p. 89) experimented with frogs subjected to weak 

 diffuse daylight, and found that they responded by moving 

 away from the light. 



VI. RESPONSE TO SUNLIGHT 



No systematic experiments were undertaken in order to deter- 

 mine the effect of sunlight on the behavior of young toads. 

 However, a few incidental observations were made and these 

 were recorded. 



The young toads were kept in a large glass aquarium jar 

 when not under experimental observation. This chanced to be 

 placed near a window with an eastern exposure. A narrow 

 beam of sunlight entered the dish, and to one side of these 

 rays of bright light was diffuse daylight. The animals jumped 

 toward the side of the jar at which the sunlight entered. Usually 

 they remained in the sunlight for some time. This response 

 seemed to vary, for certain individuals remained in the direct 

 light longer than others. However this may be, there was cer- 

 tainly a response to sunlight, evidenced by the toads jumping 

 toward the window where the sunlight entered. Frequently the 

 animals were found in the less illuminated portions of the jar, 



