COLOR AND PROTECTIVE RESEMBLANCES 



427 



the mottled gray and tawny lizards and birds and small 

 mammals of the plains and deserts, and the white hares and 

 foxes and owls and ptar- 

 migan of the snowy arctic 

 regions all show a gener- 

 al protective resemblance. 

 Sometimes an animal 

 changes color when its sur- 

 roundings change. Certain 

 hares and grouse of north- 

 ern latitudes are white in 

 winter when the snow 

 covers all the ground, but 

 in summer when much of 

 the snow melts, revealing 

 the brown and gray rocks 

 and withered leaves, they 

 put on a grayish and 

 brownish coat of hair or 

 feathers. A small insect 

 called the toad-bug (Gal- 

 gulus} lives abundantly on 

 the banks of a pond on the 

 campus of Stanford Uni- 

 versity. The shores of 

 this pond are covered in 

 some places with bits of 

 bluish rock, in others with 

 bits of reddish rock, and 

 in still others with sand. 



c r j FIG. 162. The twig or walking-stick 



Specimens Ot the toad- bug i nsec t, Diapheromera femorata. 

 Collected from the blue (From specimen.) 



rocks are bluish or leaden in color, those from the red rocks 

 are reddish, and those from the sand are sand-colored. 

 Changes of color to suit the surroundings can be quickly 



