ORGANIC EVOLUTION. 7 



cepted as the explanation of the phenomena 

 in the evolution of life on our globe. 



Darwin did not formulate his theory, but 

 after setting forth at great length the facts 

 and considerations on which his conclusions 

 were based, declared himself to be thoroughly 

 convinced that all animals and plants were 

 descended from a few progenitors (whose 

 existence he assumed), modified by second- 

 ary causes, through a long course of descent, 

 and by " spontaneous variation." 



To facilitate comparison of the two theories 

 we propose, first, to submit our theory of 

 evolution, and then to discuss the operation 

 of Darwin's secondary causes, and his inter- 

 pretations of the phenomena on which his 

 theory is based. 



