PROTECTION FROM ENEMIES 317 



in Java resemble so closely bird droppings that a trained 

 eye can not detect the difference unless at close range. 



The markings of many fish are such as to harmonize 

 so completely with the variously colored bed of the stream 

 that the casual observer will not see them when only a few 

 feet distant in clear water. The tree frog is a notable 

 example of the ability of an animal to adapt its color to its 

 environment. It is able to change its color from a very 

 dark hue to a very light one in about twenty minutes, and 

 so perfectly does it agree in color with the surface of a stone, 

 a lichen, or the bark of a tree that often one is not aware 

 of its presence until he has accidentally placed his hand 

 on it. The common frogs are likewise protected by the 

 ability to change the color of the skin. Certain lizards 

 and snakes render themselves very inconspicuous by 

 taking advantage of protective coloration. 



A woodcock on her nest has been known to have so 

 much faith in the protection afforded her by the brown- 



G. 355. Adult woodcock and twoyotmg rendered inconspicuous by their envi- 

 ronment. Photographed in American Museum. 



