DIFFERENT KINDS OF EVOLUTION 



3 



unbroken succession of individuals, to the living in- 

 habitants of the earth today. He thinks that some of 

 the simpler types of the past have in part changed 

 over into the more complex forms of the j^resent 

 time. 



Orohippus Miohippus Hipparmn Equus 



Fig. 2. — Forefeet of horses, showing the progressive loss of the lateral 

 toes. (After Marsh, from Lull.) 



He is thinking as the historian thinks, but he runs 

 the risk of thinking that he is explaining evolution 

 when he is only describing it. 



A third kind of evolution is one for which man 

 himself is responsible, in the sense that he has 

 brought it about, often with a definite end in view. 



His mind has worked slowly from stage to stage. 

 We can often trace the history of the stages through 

 which his creative j^rocesses have passed. The evolu- 

 tion of the steam-boat, the steam engine, paintings, 

 clothing, instruments of agriculture, of manufac- 



