CHAPTER XIII 

 THEORIES OF EVOLUTION 



THE circumstances surrounding the rise of evolu- 

 tion theories in the nineteenth century are not gen- 

 erally understood. There is a wide-spread belief 

 that the theory of Charles Darwin was first in the 

 field, and, confusion on this point is so general that 

 whenever organic evolution is mentioned many peo- 

 ple conclude that the particular hypothesis of Dar- 

 win is always referred to, but such is by no means the 

 case. By organic evolution is meant the great nat- 

 ural process through which animals and plants have 

 come to be what they are a purely historical ques- 

 tion of what has happened in the past to produce the 

 transmutation of animals and plants in a word, the 

 discovery of the lineage of living organisms. Dar- 

 winism, on the other hand, is one explanation offered 

 to account for the evolution of animals and plants. 

 Darwin undertakes to designate the particular 

 agency that has been at work in nature to produce 

 the various kinds of organisms. Darwinism refers 

 specifically to the action of natural selection as the 



chief agent in bringing about organic evolution. 



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