THE 



AMERICAN NATURALIST 



THE ROLE OF REPRODUCTION IN EVOLUTION 1 



The establishment of method- of reproduction which 

 maintain variation and inheritance mechanisms on a high 

 plane of efficiency is naturally a fundamental requirement 

 in organic evolution. Since, however, inheritance mech- 

 anisms presumably equivalent are commonto every method 

 of reproduction, one should be able to interpret the evolu- 

 tionary tendencies in the matter by comparing their 

 effectiveness in offering selective agencies their raw ma- 

 terial. Some will hold this statement to be a self-evident 

 truth; others may maintain as strongly either that the 

 premises are wrong or that the conclusion is not justified 

 even if the premises be granted. Perhaps it is safer to 

 ply the middle course; if the case is not so obvious as a 

 Euclidian axiom, as a compensation rigorous proof may 

 be less difficult. 



As a basis for argument, let us sketch the general trend 

 of reproductive evolution in plants and animals. 



Ordinarily, one speaks of two types of reproduction 

 among organisms, asexual and sexual. This is a conven- 

 tion that has taken on the dignity of a " folkway " among 

 biologists. Its employment should imply assent to the 

 proposition that the varied forms in which each of these 

 classes presents itself are inherently equivalent, and that 



iBea.l by title at the Symposium of the American Society of Naturalists 

 on the subject "Factors of Organic Evolution," Jan. 5, 1918. 



273 



