32 DOCTRINE OF EVOLUTION 



dissolve in water and not in alcohol before it is neces- 

 sary or desirable for him to take up the further studies 

 of the laws of solution, so reasonable grounds must be 

 found for regarding evolution as true before passing to 

 its method of accomplishment. And in the following 

 discussions, the animals will be used almost exclusively, 

 not because the study of plants fails to discover the 

 same relations and principles, but because the better 

 known animal series is more varied and extensive, 

 and above all for the reason that the human organism 

 arrays itself as the highest term of the animal series. 



In the complete scheme adopted by most naturalists, 

 five categories include the evidences bearing upon the 

 fact of evolution. These are Classification; Comparative 

 Anatomy, or Morphology ; Comparative Development, 

 or Embryology ; PalcBontology, which comprises the facts 

 provided by fossil relics of animals and plants of earlier 

 geological ages ; and Geographical Distribution. Each of 

 these divisions includes a descriptive and analytical 

 series of facts, whose characteristics are ''explained" or 

 summarized in the form of the general principles of 

 the respective divisions. Such principles, taken singly 

 and collectively, constitute the evidences of evolution. 



The particular nature of any one of these categories, 

 evolved in the development of science practically in the 

 order stated, depends upon the special quality of an 

 animal which it selects for comparison and organization 

 in connection with other similar facts, and also in its 

 own mode of viewing its facts. One and the same or- 

 ganism may present materials for two, three, or even 

 all five of these divisions, for they are by no means 

 mutually exclusive. For example, a common cat pos- 



