Notes on the Color Changes of Frogs 



Sarah Marimon 



In all these experiments I chose two identical frogs, and kept 

 one in normal conditions while the other was being subjected to 

 change. 



Tree frogs, Hyla regilla. 



I. June 16. Hot water (about 30 to 35^ C.) . Left the frogs 

 for one hour. 



The spots of the frog faded out, giving a lighter appearance. 

 However the background seemed much the same as the control. 



Control. Tap water (about 15°-17" C). Spots distinct. 

 Grayish green frog. 



II. June 17. Hot water. The frogs for this experiment had 

 peculiar red and green markings. 



The whole tone was lighter at the end of an hour and one-half. 

 Spots somewhat more indistinct than at first. 

 Control. Color unchanged. 



III. June 16. Cold water. (Cooled with ice— 2^ C.) The 

 frog was somewhat darker in color; the spots stood out more dis- 

 tinctly than previously. 



Control. Tap water (15-17' C.) Color unchanged, spots 

 showing distinctly — not so distinctly as those of the frog in cold 

 water. 



IV. June 17. Cold water, a. The frogs were rather light in 

 color. Darker spots more distinct. 



b. Two frogs grayish green in color. The color became 

 darker, spots more distinct. 



V. June 17. 5:00 P. M. Two frogs with red streaks down 

 the backs. 



One jar covered with green tissue paper, the other left as a 

 control. 



June 18. 10 A. M. Lighter in tone than the control. The 

 red streak changed to light sandy color. Spots lighter, — greenish 

 along the sides. 



Control. Same as the day before, apparently. Spots dark 

 grey, grey sides, broad reddish streak down the back. 



11 A. M. The frogs reversed. 



June 19. Red streak narrower, sandy colored. The whole 

 cast of the frog was lighter and more greenish. 



