116 DOCTRINE OF EVOLUTION 



nizing the complete naturalness of the secondary as 

 well as of the primary factors of evolution. 



The doctrine of natural selection forms the best 

 basis for the detailed discussion of the way evolution 

 has come about in the past and how it is going on 

 to-day. This is true because it was the first descrip- 

 tion of nature's program to carry conviction to the 

 scientific world, and because its major elements have 

 stood the test of time as no other doctrine has done. 

 Much has been added to our knowledge of natural 

 processes during post-Darwinian times, and new dis- 

 coveries have supplemented and strengthened the 

 original doctrine in numerous ways, although they have 

 corrected certain of the minor details on the basis of 

 fuller investigation. 



At the outset it must be clearly understood that 

 Darwin's doctrine is concerned primarily with the 

 method and not with the evidences as to the actual 

 fact of evolution. Most of those who are not famihar 

 with the principles of science beheve that Darwin 

 discovered this process ; but their opinion is not correct. 

 The reality of natural change as a universal attribute 

 of Hving things had been clearly demonstrated long 

 before Darwin wrote the remarkable series of books 

 whose influence has been felt outside the domains of 

 biology and to the very confines of organized knowl- 

 edge everjrwhere. The "Origin of Species" was pub- 

 lished in 1859, and only the last of its fourteen chapters 

 is devoted to a statement of the evidence that evolution 

 is true. In this volume Darwin presented the results 



