THEORIES OF EVOLUTION 151 



the best chance to survive. The keen vision of birds 

 of prey, such as hawks, will be a factor in their 

 preservation. Those hawks that are born with weak 

 or defective vision cannot cope with the conditions 

 under which they get their food. Natural selection 

 compels the eye to come up to a certain standard and 

 the conditions of living maintains the standard. 

 Certain animals are protected from their enemies 

 by being inconspicuous conforming to the colors 

 of the background on which they live resembling 

 twigs and other natural objects. In other cases, 

 especially among insects, flaming colors give warning 

 that the animals are of noxious taste and their 

 pursuers learn to leave them alone. An illuminating 

 instance of the action of natural selection is the 

 production of weak-winged beetles from strong- 

 winged ancestors. In very windy islands the strong- 

 winged forms being more in the air and flying further 

 from protection are blown out to sea. The weak- 

 winged are better adapted to these particular con- 

 ditions, and, natural circumstances tend to favor 

 them and to operate against the strong- winged 

 individuals. This makes one point clear natural 

 selection tends to adapt animals to their conditions of 

 life and results, not always, in the survival of the 



