THEORY OF EVOLUTION 189 



recessive one, the chance of its becoming estab- 

 lished is exactly the same. If through a muta- 

 tion a character appears that has an injurious 

 effect, however slight this may be, it has prac- 

 tically no chance of becoming established. 

 If through a mutation a character appears 



FIG. 94. Evolution of elephant's trunk. (After Lull.) 



that has a beneficial influence on the individual, 

 the chance that the individual will survive is 

 increased, not only for itself, but for all of its 



