1 6 ORGANIC EVOLUTION 



left, then, only the individuals in which these valuable 

 qualities are most highly developed. They would persist, 

 and, escaping their enemies, would succeed in rearing 

 young, to which, according to the principles of heredity, 

 they would hand down their good qualities, so that the 

 young, like the parents, would be swift and keen. Thus, 

 by the elimination of the less perfect individuals of the 

 species, there will have been developed a race of rabbits in 

 which the qualities which aid in escape from a swift, keen 

 enemy are more highly marked than in the former race. 

 This is evolution by the elimination of the unfit, or by 

 the survival of the fittest, the process which is called 

 natural selection, meaning the selection or retention of the 

 individuals most perfectly adapted to the environment in 

 which they live. 



The new race referred to in the illustration chosen 

 might be especially characterized not only by the two 

 qualities mentioned, swiftness and keenness, but also very 

 likely by other qualities that would aid in escaping the 

 new enemy, such, for example, as more perfect conformity 

 in color to the environment, provided its conditions of 

 life had been so easy that perfect color resemblance to the 

 environment had not been previously a necessity. Several 

 of the desired qualities could probably be perfected at the 

 same time, since the variations from which to select would 

 not appear separately in different individuals, but would 

 often be present in the same individual at one time. 

 Thus there would be found amoncr our Eastern rabbits 



O 



some which were at once more swift, more keen-sighted, 

 more observant, more shy, more perfectly like the environ- 

 ment in color, and perhaps marked by special development 



