424 GENERAL BIOLOGY 



counteract the body's own shadow. This is well nigh uni- 

 versal. That it is of primary importance in bringing about 

 inconspicuousness any one may demonstrate by placing two 

 skins of any common gray bird or mammal on the bare 

 ground, one back upward in its normal position, and the 

 other back downward, and then looking at them from a little 

 distance. The conspicuousness of the gray of the body 

 when the shadow of the body is added to it will be most 

 striking, and the advantage of the lighter countershading 

 will be apparent. And if one look carefully at a living or 

 well mounted specimen of a sandpiper or a wild gray rabbit, 

 he will see how delicately this shading and countershading 

 is wrought; each little projecting ledge is overspread with 

 darker pigmentation; and underneath is a lighter area, as 

 under the orbit, under the ear, or under the chin. 



That this plan of ground coloration is adaptive, is evi- 

 denced by those animals that move habitually in an inverted 

 position, as the sloth, that travels hanging by its claws 

 beneath the boughs of forest trees, and the back swimmer 

 that swims with its back downward in the pond. Such 

 forms have the counter shading of lighter color on the back. 



Resemblance is .spoken of as protective, helping its 

 possessor to escape its enemies, or aggressive allowing its 

 possessor to approach unobserved nearer its prey; but 

 the difference is not in the coloration, but in the purpose it 

 serves. This finds its analogy in the devices to which men 

 resort. The modern soldier not wishing to offer in himself 

 a good target, wears a khaki uniform; and the hunter, 

 desiring to get closer to his game, adopts outer clothing of 

 similar inconspicuous color. The gray mixed coloration of 

 the rabbit or the roadside grasshopper or the green of the 

 meadow grasshopper, and that of most herbivorous animals 

 is protective; while the same colors in the lynx and the 

 mantis, and in most carnivorous species are aggressive. 



