EVIDENCES FOR THE THEORY 29 



convincing, yet the harmony of all of them, all point- 

 ing in the same direction, greatly strengthens the 

 proof and raises the theory to a very high order of 

 probability, despite the many unanswered questions 

 and unsolved problems. Classification, comparative 

 anatomy, embryology, palaeontology, the geographi- 

 cal distribution of animals and plants, all tell the 

 same story. It is because in every department of 

 zoology and botany the evolutionary hypothesis 

 offers the simplest, the most rational and the most 

 satisfactory explanation of the observed facts, that 

 naturalists accept it almost unanimously. 



In order to explain the character of the living world 

 and what is known of its history, but two alternative 

 hypotheses have been propounded. The first, called 

 the doctrine of Special Creation, holds that each 

 kind of animal and plant was created in its present 

 form and is substantially immutable. This doctrine, 

 formulated by Linnaeus, was very widely adopted 

 and held the field until the publication of Darwin's 

 book. The second is the hypothesis of evolution, or 

 "descent with modification," according to which all 

 animals and plants, as we know them, have been 

 developed from primordial germs, leaving open the 

 question as to how life on the earth originated. If 

 any one declines to accept either one of these hy- 

 potheses, it only remains to admit that the problem 

 is a complete mystery, for which no solution has been 

 found, the position taken by Fleischmann. In mak- 

 ing a choice between these alternatives, it often 



