CHAPTER I 



A RE VALUATION' OF THE EVIDENCE ON 



WHICH THE THEORY OF EVOLUTION 



WAS BASED 



We use the word evolution in many ways — to 

 include many different kinds of changes. There 

 is hardly any other scientific term that is used 

 so carelessly — to imply so much, to mean so 

 little. 



Three Kinds of Evolution 



We speak of the evolution of tlie stars, of 

 the evolution of the horse, of the evolution of 

 the steam engine, as though they were all part 

 of the same process. A^Hmt have they in com- 

 mon? Only tliis, that each concerns itself with 

 the luHtory of something. When the astron- 

 omer thinks of the evolution of the earth, the 

 moon, the sun and the stars, he has a picture of 

 diffuse matter that lias slowly condensed. With 

 condensation came heat; with heat, action and 



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