EXPERIMENTS ON PROTECTIVE COLORATION 475 



one minutes a hawk flew to the ground at the middle of the cage and 

 ahghted facing the mice, l^ut they were apparently not seen. Four 

 minutes later it ran slowly to the mice and took one from the ashes. 



Experiment 14- Figures 1 and 16. Two Mus were placed on ashes, 

 and two on earth covered with dead leaves. The contrast between the 

 mice and the former was greater than between them and the latter 

 background, but the resemblance with the latter was not very striking. 

 About fifteen minutes later one hawk flew to the ground within a 

 short distance of the mice, but apparently did not see them. A few 

 minutes later the other did the same, and fifteen minutes later flew 

 over the mice alighting near them, but taking no notice of them, Theii 

 for twenty minutes the experiment was not observed. During this 

 time both mice were taken from the ashes and neither from the leaves, 

 although the latter were not over 22 or 23 cm. from the former. 



Experiment 15. Figures 13 and 16. Two Mus were placed on 

 ashes and two on dead leaves. The former combination showed 

 the greater contrast, but the resemblance between the mice and the 

 leaves was only fair. In twenty-eight minutes a hawk ran across the 

 cage to where the mice were, and returned without feeding, twice repeat- 

 ing this performance a few minutes later. About an hour after the 

 experiment started another hawk took one mouse from the leaves.-" 

 I failed to observe whether the hawk went directly to the mice or not. 



Experiment 16. Figures 19 and 20. Two Epimys were placed 

 venter uppermost, one on ashes and one on moist earth. Both were 

 partly imbedded in the backgrounds, so as to expose only the ventral 

 surface. As I viewed the backgrounds from the opposite end of the 

 cage the former rat was clearly visible, but the latter was the more 

 conspicuous. Seventy-two minutes after the experiment was started 

 a hawk approached the backgrounds and stood inspecting the rats 

 until another hawk ran from the opposite end of the cage and took the 

 rat from the earth. It was growing dark at this time. 



Experiment 17-. Figures 22 and 23. Two Epimys were placed on 

 powdered gypsum and two on dead leaves, sticks and straws mixed 

 with a little clay. The resemblance between the rats and the latter 

 background was not very close, as viewed from the opposite end of 

 the cage, but was much closer than that of the rats to the gypsum. 

 For several hours (exact time not recorded) the rats were not taken by 

 the hawks, although the latter frequently looked toward them and one 

 once or twice alighted within about 3 m. of them. I then tied a string 

 to one of the rats and jerked it repeatedly, causing the hawks to look 

 toward the rats, but without any move to take them. I then removed 

 a rat from each background, leaving one on each, and ceased observ- 

 ing the experiment for twenty-five minutes. Returning at the end of 

 this time, I found one of the hawks eating the rat on the gypsum. The 

 hawks were undoubtedly hungry in this experiment as they had had 

 only one rat between them during the two preceding days, and why 



-° That one of the two was taken which resembled its backf^round less closely. 



