BEHAVIOR AND COLOR CHANGES OF TREE FROGS 73 



to the effect of high temperature; a given specimen showing 

 no distress at a temperature of 35 degrees or even 36 degrees C, 

 while another w T ould actually collapse at 30 degrees. This was 

 repeatedly shown, both in the bath and in the oven. In every 

 case, however, removal from the bath was followed by rapid 

 recovery, except in one case where some two hours was neces- 

 sary for complete recovery. 



Following the tests for high temperature there was a subjec- 

 tion of specimens to greatly lower temperature. For example, 

 a specimen was taken from the 35 degree bath and placed in 

 one of 10 to 12 degrees. In this reversal of the temperature 

 there was, as in the case of darkness, an almost invariable 

 negative, i.e., there was no tendency to induce a corresponding 

 darkening of the color. It frequently happened that the light 

 color would persist for from one to several hours, though in 

 most cases the resumption of the original color followed in about 

 an hour. But in any case it was quite evident that the 

 cold bath showed no tendency to hasten the matter. 



It was said above that exceptions- were not wanting. One 

 has already been mentioned which showed a directly contrary 

 color change. This was also the case with one other specimen. 

 It remains to mention the fact that still others failed absolutely 

 to show any response whatsoever. They were first subjected to 

 a temperature of 30 , then to one of 35 , and finally to a still 

 higher, but under the ordeal they remained neutral, or with 

 a slight darkening of color in one. 



Here as in preceding experiments with light we • have not 

 only such individual differences as might be expected, but we 

 have actually contradictory results, or what seem to be such. 

 The question may arise, Are they really such? In the light 

 of all the facts I am prepared to answer this query in the nega- 

 tive. Not only are they not contradictory, on the other hand 

 they but emphasize afresh the conclusion elsewhere enunciated 

 by the writer that we are here dealing with sentient, volitional 

 individuals, whose behavior is involved in exceedingly complex 

 nervous and physiological states, the nature of which we may 

 hardly dare to guess. • That they are creatures subject to vary- 

 ing stimuli every day, and meet them variously, may be accepted 

 as a matter of course. That in response to the more common 

 of these stimuli there comes about a general correspondence or 



