spicuous those species which we most commonly see against the wrong back- 

 ground. This is what Darwin and Wallace did, — and, failing to understand 

 the effect both of pattern and of visibility through contrast and silhouette, 

 they made the fundamental mistake of ascribing the conspicuousness to the 

 very thing which opposes it. Their immense prestige has so riveted this 

 error in students' minds as to have doomed the whole subject, hitherto, to 

 confusion and neglect. 



Naturalists repeatedly experience the difficulty of detecting brilliantly 

 colored birds and strongly marked quadrupeds — commonly recording each 

 case as surprising or inexplicable under the supposed circumstances, or some- 

 times manifesting a true apprehension of some one particular case, without 

 seeing that they are dealing with a universal principle.* 



Among the aboriginal human races, the various war-paints, tattooings, 

 head-decorations, and appendages, such as the long, erect mane of eagle 

 feathers worn by North American Indians, — all these, whatever purposes their 

 wearers believe they serve, do tend to 'obliterate' them, precisely as similar 

 devices 'obliterate' animals. 



The color-relations of earth, sky, water, and vegetation are practically 

 the same the world over, and one may read on an animal's coat the main 

 facts of his habits and habitat, without ever seeing him in his home. 



Abbott EL Thayer. 



Monadnock, N. H., December 15, 1907. 



* Here is a simple way to discover whether one has the full color sense necessary as a basis for 

 studying obliterative coloration. If, like a multitude of people, one cannot see that shadows on an 

 open field of snow, or on a white sheet, under a blue sky, are bright blue like the sky overhead, one 

 will probably prove more or less defective in all color-perceptions. To prove that such shadows 

 are sky colored, lay a colorless mirror on the snow in such a shadow, — its reflected sky will match the 

 surrounding snow. 



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