ADAPTATION OF ORGANISMS 319 



the adaptability of the Mammal stock its potential of 

 evolution is in no small degree responsible for the 

 dominant position which the Mammals hold in the animal 

 world of to-day. Man is a Mammal. 



ANIMAL COLORATION. Perhaps the most generally strik- 

 ing characteristic of organisms is their color and color 

 pattern. Among plants this applies chiefly to the flowers 

 and fruit of the higher forms, though here and there through- 



FIG. 169. The common green Katydid (Microcentrum). 

 (After Riley.) 



out the plant series the typical green color is replaced or 

 rendered inconspicuous by others. But the absence of photo- 

 synthetic 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 ex- 

 planation 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 

 creatures and render them practically indistinguishable from 

 their immediate environment. Every frequenter of the open 



