RELATIONS AND SURROUNDINGS. 141 



means of what is known as protective resemblance. Be- 

 cause of its form or color, or both, an animal may become 

 much like its surroundings (Figs. 29, 30, 31), and thus 

 escape observation. Sometimes this resemblance is to 

 some particular object; sometimes merely a general 

 harmony with the surroundings. Illustrative of the 

 latter are the green caterpillars and tree-toads among the 



FIG. 30. Walking-stick insect (Diapheromera veliei) on twig. Natural size. 

 By J. W. Folsom. 



Questions on the Figure. To what group of insects does it belong ? 

 Do you see any reason to believe that it illustrates protective resemb- 

 lance? Compare other figures in the reference texts. 



green leaves ; the quail among the dead leaves and grasses ; 

 the lizard on the lichened rock, the tawny color of desert 

 animals, and the white fur of arctic forms. Most animals 

 show some of this general likeness to surroundings, for it 

 is advantageous both to the hunter and to the prey. 



Many animals become inconspicuous by reason of 

 resemblance to special objects. The walking-stick insects 

 (Fig. 30) appears as a dead twig, when not in motion. 



