ADAPTATION FOR THE INDIVIDUAL 1 05 



ttire has concocted many devices by which she assists 

 her favored children in escaping this relentless perse- 

 cution. Perhaps the most widespread means which 

 animals have developed in order to elude their ene- 

 mies lies in the possession of power to escape their 

 attention. Two different factors may contribute to 

 this end. The first of these consists in the practice on 

 the part of many animals of remaining absolutely 

 quiet in time of danger. This instinct seems to be 

 nearly universal. The first impulse of most animals 

 upon discovering danger is to remain absolutely mo- 

 tionless. The eye detects, with ease, objects in mo- 

 tion. These same objects might entirely escape atten- 

 tion were they quiet. A mouse could remain in the 

 corner of a room for a long time without attracting 

 the eyes of the occupants of the room. Let it but 

 scamper across the corner, and at once it is discov- 

 ered. It is quite conceivable that early animals were 

 divided in the matter; that the impulse of some was to 

 escape from danger, while others, frightened by the 

 presence of the enemy, remained absolutely still. Each 

 plan has succeeded. Those which, on running, ran 

 fast enough to escape became the parents of others 

 like themselves, led eventually to a line of animals in 

 whose speed lay their safety. Those, however, which 

 attempted to escape, and failed because they were not 

 swift enough, had their line cut off, and were thus 



