EVOLUTION OF THE COLORS OF BIRDS. 23i 



after being removed into the light. The very general 

 absence of color in cave-dwelling animals is itself a 

 very strong argument in favor of the influence of light 

 in developing pigment. " AVhat we do find," says Bed- 

 dard, in commenting upon the argument that the lack 

 of pigment in cave-dwelling forms is due simply to the 

 need for color being obviated, " is a uniform absence of 

 pigment, which is highly suggestive of a direct action 

 of the environment — and an environment obviously 

 different from that which has caused or permitted the 

 bright and varied coloration of deep-sea animals." 



Mr. S. W. Garman published in the Proceedings of the 

 American Association for the Advancement of Science 

 in 1877, * a paper on Variation in the Colors of Animals, 

 in which he advocated a view which appears in direct 

 opposition to the evidence above adduced — viz.: that the 

 pale colors of animals are produced by the bleaching 

 power " exerted by the confusing blending prismatic re- 

 flection of sands and snows," etc. This law of the bleach- 

 ing power of reflected light he considers as the universal 

 cause of pale or white coloration, accounting for the 

 pallor of desert forms and the white or pale color of the 

 underparts of so many animals. Besides the evidence 

 above adduced which goes to negative this view I need 

 only to call attention to the white-bellied and violet- 

 green swallows which have such pure white breasts and 

 yet spend nearly all their time in the free open air far 

 above any influence of reflected light, and the fish crow 

 and raven which live along the sands of the sea shore 

 where the reflected light is full as bright as on the desert, 

 and yet show not the slightest intimation that they have 

 any idea of relinquishing their proverbial garb of black. 



Again, it will be found that the abdomen is far more 

 frequently white than the breast — in fact the color gen- 



' VoL XXV, pp. 187-204. 



