ORGANIC RESPONSE 267 



fluid. When one of these mollusks is attacked, it 

 beclouds the water by spurting out this fluid, and, 

 under cover of this protection, makes its escape. 



Protective Coloration. Most striking of all adap- 

 tations whereby animals escape their enemies is 

 that of protective coloration. A bird darts into a 

 thicket and, strain our eyes as we may, we cannot 

 see where it has gone. A grasshopper is started up 

 and whirs away, conspicuously visible on account 

 of the brilliant coloration of its wings, only to dis- 

 appear utterly from sight as it drops back again 

 into the grass. The bright colors are covered up, and 

 the coloration of the outer surface of the body merges 

 into that of the creature's surroundings. Not the 

 least effective element of its disappearance is the 

 sudden and bewildering contrast between the con- 

 spicuousness of the insect's appearance at one 

 moment and its inconspicuousness at another. 

 This condition extends to many unrelated types of 

 animals. Along the white sandy stretches of the 

 sea-shore, or the bare rocks and sands of the desert, 

 practically all animal life partakes of the same 

 whitish, inconspicuous ground-color. In the leafy 

 depths of the forest the inhabitants are likely to be 

 green as well. Familiar examples of forms that show 

 such protective coloration are the tree-frog and the 

 katydid, or the fishes that live among the sea-weeds 

 in a tide-pool. Often an animal that appears to be 

 most conspicuously marked when isolated on a 

 museum shelf merges perfectly into its environment 



