DEVELOPMENT 439 



rivals requiring the same food and locality, or enemies, 

 for the vast majority of animals are carnivorous. Off- 

 spring are continually varying from their parents, for 

 better or worse. If feebly adapted to the conditions of 

 existence, they will finally go to the wall. But those 

 forms having the slightest advantage over others in- 

 habiting the same region, being hardier or stronger, 

 more agile or sagacious, will survive. Should this ad- 

 vantageous variation become hereditary and intensified, 

 the new variety will gradually extirpate or replace other 

 kinds. This is what Mr. Darwin means by Natural 

 Selection, and Herbert Spencer by the Survival of the 

 Fittest. 



