CHAPTER I 



A REVALUATION 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 the stars, of 

 the evolution of the horse, of the evolution of 

 the steam engine, as though they were all part 

 of the same process. What have they in com- 

 mon ? Only this, that each concerns itself with 

 the history 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 has slowly condensed. With 

 condensation came heat; with heat, action and 



