the powerlessness of mere similar colors to conceal could hardly be devised. 

 So, were it not for his obliterative shading, would the leopard or jaguar show 

 up in the forest, despite his richly spotted forest-pattern. 



Fig. 7 shows a pure white hen, photographed against a white cloth, an- 

 other illustration of the ineffectuality of mere color-resemblance. The hen 

 is conspicuously solid, her back showing light and her belly dark against the 

 flat white plane of the cloth. Every part of her surface, in fact, except for a 

 few mere points of transition, is either too dark or too light to match her back- 

 ground. A ptarmigan in winter plumage lacks the advantage of counter 

 shading, and must needs lack it, since even the middle of its back has to be 

 white to match its pure white snowy background, and nature can furnish 

 nothing lighter than white feathers for the bird's underside. But the up- 

 ward reflection from the snow itself goes far toward canceling the shadow 

 on such animals. (See Figs. 8-10.) In the same way the reflection from 

 bright sand cooperates with the delicate counter shading of desert animals, 

 which are usually very light colored. Such creatures are also as a rule al- 

 most unmarked, and thus furnish good examples of the use of obliterative 

 shading, pure and simple. It is on a delicate scale, however, since there is 

 but a short range of shade between pure white and the delicate brown re- 

 quired to make the animals' backs ' coalesce' with the sand. Desert animals 

 are of course habitually exposed to full sunlight, but the excess of shadow 

 which the undersides of sunlit animals normally bear,* is in this case almost 

 or quite counteracted by the light-reflecting power of the bright desert sand. 

 Many forest animals, on the other hand, wear a slight counter shading at the 

 dark end of the scale— that is, from some dark color to a very slightly lighter 

 tone — because of the extreme diffuseness of the light in shady forest recesses, 

 whose colors are mainly dark and rich. The need of extreme counter shading 

 — from very dark to purest white — seems restricted mainly to high-standing 

 animals which live in the open on dark ground. On such a one the direct 

 sky-light makes its full graduated shading, and the shadow of the undersides 



*See p. 18, Chapter I. 

 26 



