CHAPTER VII 

 EVIDENCES OF EVOLUTION 



1. EXISTING ORGANISMS 



Relationship. The facts set forth in the four preceding chap- 

 ters are such as to leave no logical doubt of the relationship of the 

 various kinds of organisms now extant. It is obvious that there is 

 some degree of resemblance between any species which we may 

 choose, no matter how remote they may seem, even though extreme 

 cases force us back to the cell as a common basis of structure and 

 protoplasm as the one living substance. Other things may be 

 fundamentally different, but these at least connect all living 

 creatures. 



The entire body of scientific facts is merely an elaboration and 

 extension of such obvious things as we have assumed to be man's 

 first observation of organic relationship. While some organisms 

 are very obviously related, others are less evidently so, but through 

 his gradual accumulation and interchange of knowledge, man has 

 arrived at an understanding of organic unity. Science makes 

 clear the fact that relationship among organisms is universal. 



The Significance of Relationship. The interpretation of such 

 facts beyond this point is somewhat different. To the scientific 

 mind they can have only one meaning, but it is evident that there 

 are others who find it possible to believe in the independent origin 

 of these related organisms. When men were struggling to explain 

 such natural phenomena as are in accord with evolution, even the 

 contemporary origin of new organisms from inorganic sources did 

 not seem absurd to them. We are now in possession of abundant 

 evidence of the non-existence of spontaneous generation as a 

 source of organisms, but the dim records of the past are less easily 

 demonstrated by empirical methods. The nature of organic rela- 

 tionship must therefore be based on logical interpretation of the 

 available facts. Whether or not the processes which have come 

 to be accepted on this basis will some day be demonstrated in the 

 laboratory, it remains for the future to prove. Many things are 



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