II 



THE STRUCTURE AND DEVELOPMENT OF ANIMALS AS 



EVIDENCE OF EVOLUTION 



In order to become acquainted with the way the 

 structures of animals provide evidences of evolution, it 

 is by no means necessary to review the entire range of 

 their forms, because research has discovered that the 

 principles of relationship are universal among animals, 

 and that any group of examples will demonstrate what 

 is taught by comparative anatomy as a whole. The 

 commonest creatures may serve us best in order that 

 we may come to view evolution as a process that in- 

 volves each and every living thing that we know, and 

 not as something which belongs only to the remote and 

 unknown past. 



Let us begin with the common cat and the group of 

 carnivora or flesh-eating animals to which it belongs. 

 As we pass along the streets of the city, we will see many 

 cats which differ in some details, though they resemble 

 one another closely. While they vary somewhat in 

 form, the range in this quality is not so noticeable as in 

 the matter of color; some of them will be gray, some 

 maltese, while others will be yellowish or black, and 

 they will differ in the striped or spotted character of 

 their coloration. We readily classify them all as ^' cats " 

 in spite of their differences, because they are alike in 



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