ADAPTATION TO ENVIRONMENT 27 



tion not preempted by others and coming finally to 

 depend upon its one particular mode of defense. Here, 

 a weak, stupid animal is sheltered under a shell or 

 carapace, leading its narrow life in the very shadow 

 of fierce and powerful animals, yet effectively pro- 

 tected from them. Here, another flits from limb to 

 limb lightly, pecking its food daintily, hiding its eggs 

 carefully, and skillfully deceiving or diverting its wily 

 and more powerful enemies. Here, a sleek and lazy 

 creature, without shell or armor, wings for flying, 

 or claws for fighting, keeps its enemies at a distance 

 by the production of an acrid or repellent odor. Here 

 a slipping, sliding thing effects by fangs and venom 

 what its neighbor accomplishes by a barbed skin or 

 a repulsive emanation. Here, a huge forest prowler, 

 muscled as with whipcord, survives by sheer strength, 

 while another, lacking this strength, depends upon 

 the fleetness of its limbs, the keenness of its eye, the 

 acuteness of its hearing, living on its wits as verily 

 as any human adventurer. Here, a delicate little 

 creature, like the field mouse, preyed upon by every- 

 thing in its neighborhood snake, hawk and owl, 

 lacking any of the more powerful defenses, survives 

 by the sheer fact of its great fertility. Here, the ele- 

 phant, slowest of breeders, being superior to attack, 

 stalks unmolested through the forest, but finds its 

 struggle in a hunt for food. 



In every case the fate of each creature seems to have 

 been staked upon one mechanism. The tiger by its 

 teeth and claws, the elephant and the rhinoceros by 

 their strength, the bird by its wings, the deer by its 

 fleetness, the turtle by its carapace all are enabled 



