RESPONSES OF YOUNG TOADS 195 



glowers for the source of illumination, and showed that members 

 of both species reacted by giving motor responses, turning and 

 jumping toward or away from the light. In one series of experi- 

 ments with blue light, there were 251 positive responses and 37 

 negative ones. In another series of experiments with red light, 

 there were 167 positive responses and 121 negative ones. The 

 former series shows the percentage of responses to be 87 positive 

 to 13 negative, while the latter series shows the percentage of 

 responses to be 58 positive to 42 negative. 



"By way of summarizing the results of the experiments with single 

 monochromatic lights in which both the eye and the skin acted as recep- 

 tors, it may be stated that all four colored lights used produced positive 

 responses. Blue light was the most effective, and the other lights formed 

 a decreasing series, corresponding roughly to their relative position in 

 the spectrum, the red light being but slightly more effective than dark- 

 ness." (Laurens, I.e.) 



This summary presents results which are in extremely close 

 agreement with those of Pearse (I.e.) on Rana palustris. 



Some observations were recorded when stimuli from light of 

 different colors, red and blue, were impinging upon the toads 

 at the same time. The glass vessel containing the animals was 

 so placed that the red light was situated at one extremity and 

 the blue light at the other. The position was such that one end 

 of the dish was in the beam of red light and the opposite end in 

 the beam of blue light. 



The young toads are placed in the center of the dish, approx- 

 imately half way between the lights passing through the red 

 and blue solutions. There is little more exhibited in the result- 

 ing responses than has already been recorded with reference to 

 the single colored light. Orientation and movement toward the 

 blue light are more definite and more vigorous, than they are 

 with respect to the red light. By far the majority of the animals 

 jump toward the blue light. A few individuals jump toward 

 the red light. These make longer pauses between the jumps 

 than is the case of those toads moving toward the blue light. 

 Frequently periods three minutes or more in duration elapse 

 between some of the jumps. At times one or two specimens 

 appear to be indifferent to either light. In several instances 

 observations were recorded after a period of fifteen minutes 

 from the time the toads were first placed in the experimen- 

 tation dish. In these experiments twelve toads are used each 



