30 Journal of Entomologx' and ZooIo^n 



2. The frog does not actually change color so much as it gets 

 lighter or darker in response to stimuli. There seems to be, how- 

 ever, some actual change in color. 



3. The colors, blue, green and yellow cause the frog to get 

 lighter in color. The results with red were so irregular as to sug- 

 gest that the change might be due to some other agent than the color 

 environment. 



4. When there is a reddish color present, i. e., red streak, the 

 red environment intensifies this coloration. When, however, there 

 is no red color present the red environment does not develop it. 



5. This same phenomena is true of green coloration. Thus a 

 red frog does not seem to be able to change into a green one, nor a 

 green frog into a red one. 



6. The changes in coloration or intensity seem to be due to 

 the expansion of the pigment cells. 



Experiments ivith Rana sp. 



I. May 26. Light. I left the frog in the light (sunlight, 

 although not direct) for one hour. At the end of this time it was 

 remarkably lighter than the one in the dark room. 



II. May 26. Dark. Frog like the one in light. I left it in 

 the dark room for one hour. At the end of this time it was much 

 darker than the one in the light. 



Reversed frogs. 



Left two hours. At the end of this time the two frogs were 

 the same color again. 



May 28. Repeated the first step of the light and dark experi- 

 ment with the same results. 



May 29. Placed one frog on a white reflecting surface but not 

 in the sunlight. In one hour very little change. 



At the end of the hour, placed the frog in the sunlight, still 

 on a white, reflecting surface. Remained there for one hour. At 

 the end of this time it was very much lighter than the one in the 

 semi-darkness. 



Sunlight then has more efl'ect than diffused light, or perhaps 

 the diff'erence is caused by the difference in temperature. 



III. May 29. Placed one frog in a rather dark but not abso- 

 lutely dark place, used rather as a control than as an experiment. 

 Apparently it did not change color. 



Left it for another hour. The supposition was that it did not 

 change color in the second hour, since the first hour had no efl'ect. 



However at the end of the hour it was much darker than the 

 one in the sunlight. 



