ON THE QUICK GROWING WALNUT 



Alfred Russell Wallace conceived the same idea 

 independently, and must always be credited with 

 a share in the discovery. 



But of course it was Darwin's exposition that 

 gave the subject general vogue, and the scheme of 

 heredity that it connotes is with full propriety 

 spoken of as Darwinian evolution. 



The essentials of this scheme of heredity may 

 be stated in a few words, as follows: Animals and 

 plants tend to increase in geometrical ratio. If 

 unopposed, the progeny of a single pair of animals 

 or an individual plant would soon populate and 

 over-populate the entire earth. Opposition to such 

 over-population comes from the rivalry of other 

 animals and plants. The struggle for existence 

 thus induced puts a premium on the individual 

 animal or plant that is better able than its fellows 

 to seek means of sustenance. Such an individual 

 will, on the average, live longer and produce more 

 offspring than an individual less well adapted to 

 its surroundings. 



The preservation of these favored individuals 

 and their progeny may be described in a phrase 

 as "the survival of the fittest." 



The natural processes that determine such sur- 

 vival on one hand, and the destruction of the less 

 fit on the other, may be spoken of as constituting 

 "natural selection." 



[207] 



