ORGANIC ADAPTATION 325 



plants this applies chiefly to the flowers and fruit of the higher 

 forms, though here and there throughout the plant series the 

 typical green color is replaced or rendered inconspicuous by others. 

 But the absence of photosynthetic pigments in animals and their 

 relatively active life have permitted more latitude in body color, 

 and accordingly it is in the animal world that color adaptations 

 are more numerous and varied. Some colors and color patterns 

 are, of course, merely incidental to the chemical composition of 

 the whole or parts of the body. Others, however, irresistibly arouse 

 our interest and seem to demand a less simple explanation because 

 they are apparently of special service to their possessors. A few 

 examples will serve to bring the problem before us and indicate 

 the class of facts involved. 



The color and color patterns of many animals are such that 

 they harmonize or fuse with the usual surroundings of the crea- 



Fig. 209. — The common green Katydid, Microcentrum. (From Riley.) 



tures and render them practically indistinguishable from their im- 

 mediate environment. Every frequenter of the open knows innu- 

 merable instances. The song of the green Katydid readily guides 

 one to its immediate vicinity, but it is quite another matter to dis- 

 tinguish its leaf-green wings among the foliage of its retreat. Again, 

 one is attracted by the striking colors of an Underwing Moth while 

 in flight, but is at a loss to find the insect when scarlet or orange is 

 obscured by the overlapping, grayish-mottled fore-wings blending 

 with the tree trunk where it has come to rest. (Figs. 209, 210.) 



The white of the Foxes, Hares, and Owls of alpine and arctic 

 regions; the green color of foliage-dwelling Toads and Frogs; the 

 tendency toward fawn and gray of desert Insects, Reptiles, Birds, 

 and Mammals; the olive upper surface of the bodies of brook 

 Fishes; the steel gray above and white below of sea Birds that 

 harmonize with sea and sky when viewed from above and below 

 respectively — the number of such cases is legion. Gazelles living 



