RESPONSES OF YOUNG TOADS 187 



end of the vessel facing the light, was removed. Such an ar- 

 rangement modified, considerably, the effects of the cross rays. 



It is noticed, after the dish containing the toads has been 

 near the window for a few seconds, that the animals orient 

 themselves with their heads toward the source of light and 

 with the long axes of their bodies parallel with the longitudinal 

 axis of the vessel used for the reaction work, but not parallel 

 with the great majority of the rays, for these enter the dish at 

 various angles notwithstanding the precautions already de- 

 scribed. The toads jump away in a comparatively straight line 

 toward the light. All the organisms are soon congregated at 

 the end of the trough nearest to the window. Not infrequently 

 some of them climb up the glass wall at the end of the dish and 

 cling in that position. The vessel is turned around until the 

 end where the toads are gathered is pointing directly away 

 from the window. Those that are clinging to the glass side 

 drop down to the floor of the trough. All the animals again 

 turn their heads toward the window and move off, with the 

 long axes of their bodies parallel with the longitudinal axis of 

 the experimentation dish, in the direction of the source of illu- 

 mination. In a short time they are all found at the extremity 

 of the vessel. Experiments of this nature are continued for 

 eight successive trials. Each time the animals move promptly 

 from one end of the dish to the other. As in the experiments 

 with incandescent electric light, there is evidence that orienta- 

 tion does not occur quite so promptly nor is locomotion so 

 rapid as in the experiments with the projection lantern. 



These experiments appear to indicate that young toads respond 

 positively to diffuse daylight of somewhat strong intensity. 

 They also exhibit definite orientation with the anterior end of 

 the body turned directly toward the light. But it cannot be 

 said that the long axis of the body lies parallel to the incoming 

 rays, for it is evident after careful consideration that these must 

 enter the experimentation trough at many and varied angles, 

 numbers of them passing, more or less, along its entire length. 



The responses of toads and frogs to strong diffuse daylight 

 have been observed by other workers, and a brief comparison 

 will be made with the results of some of their experiments. It 

 is of interest to notice that, Graber (1884, p. 124) found that 

 toads, Bnfo vulgaris Laur, placed in a box with two compart- 



