CHAPTEE XXIV 



PROTECTIVE RESEMBLANCES, AND MIMICRY 



280. Protective resemblance defined. If a grasshopper 

 be startled from the ground, you may watch it and deter- 

 mine exactly where it alights after its leap or flight, and 

 yet, on going to the spot, be wholly unable to find it. The 

 colors and marking of the insect so harmonize with its sur- 

 roundings of soil and vegetation that it is nearly indistin- 

 guishable as long as it remains at rest. And if you were 

 intent on capturing grasshoppers for fish-bait, this resem- 

 blance in appearance to their surroundings would be very 

 annoying to you, while it would be a great advantage to 

 the grasshoppers, protecting some of them from capture and 

 death. This is protective resemblance. Mere casual obser- 

 vation reveals to us that such instances of protective resem- 

 blance are very common among animals. A rabbit or grouse 

 crouching close to the ground and remaining motionless 

 is almost indistinguishable. Green caterpillars lying out- 

 stretched along green grass-blades or on green leaves may 

 be touched before being recognized by sight. In arctic 

 regions of perpetual snow the polar bears, the snowy arctic 

 foxes, and the hares are all pure white instead of brown 

 and red and gray like their cousins of temperate and warm 

 regions. Animals of the desert are almost without excep- 

 tion obscurely mottled with gray and sand color, so as to 

 harmonize with their surroundings. 



In the struggle for existence anything that may give 

 an animal an advantage, however slight, may be sufficient 

 to turn the scale in favor of the organism possessing the 

 350 



