EXPERIMENTS ON PROTECTIVE COLORATION 477 



For a few days it was fed by hand, but it soon learned to feed 

 itself. The experiments were conducted in the same cage in 

 which Series V was conducted. The backgrounds were arranged 

 at one end of the cage and the prey placed on them while the 

 owl was perched at the opposite end, care being taken, as in the 

 other experiments, to conceal the mice from the view of the 

 owl while they were being placed on the backgrounds. In all 

 of the experiments to be recorded the contrast between the 

 mice and the white background (snow or powdered gypsum) 

 was much greater than between the mice and the other back- 

 ground. ^i Being performed at dark or later, the effect of the 

 former background in rendering objects placed upon it con- 

 spicuous in comparison with those on the other backgrounds 

 was much enhanced. The resemblance between the mice and 

 the latter backgrounds may have been greater to my eye than 

 to that of the owl, since its eyes were adapted to night vision. 

 When the owl was transferred from the small to the large cage 

 and mice first placed on the backgrounds, it left them untouched 

 for about three hours, at the end of which time, observation was 

 suspended. It soon learned however to feed from the back- 

 grounds and did so much more readily than the hawks in Series 

 IV and V. 



Experiment 1. Figures 7 and 11. Four mice were placed on snow 

 and four on dead leaves mixed with earth and clay. Fifteen minutes 

 later three mice had been taken from the snow. 



Experiment 2. The arrangement of prey and backgrounds was the 

 same in this experiment as in the preceding, except that only two 

 mice were placed on each background. In less than an hour^^ one 

 mouse was taken from the snow. 



Experiment 3. Figure 14- In this experiment three mice were 

 placed venter uppermost on partly moist clay and three in a similar 

 position on moist earth. The clay and earth backgrounds occupied 

 the same relative position as the snow and leaves in the preceding ex- 

 periment. At the time of this experiment, the latter combination, 

 as seen from the opposite end of the cage, presented a much greater 

 contrast than the former. Within about five minutes the mouse 

 nearest the clay background was taken from the earth. 



Experiment \. The same as Experiment 3, except that the clay 

 had become more moistened by the underlying damp earth, and the 



-1 Experiments 3 to 5, 9, 10 excepted. 

 -- Exact time not noted. 



