CHAPTER XXV 

 EVOLUTION TODAY 



At no time in the history of biology has evolution occupied a 

 more important place in scientific thought than now. It permeates 

 the entire fabric of organized scientific knowledge and furnishes 

 the guiding principle in much, if not all, biological research. The 

 value of its established facts is recognized, but more than that, 

 the value of accurate understanding of the methods by which it 

 works impresses itself upon our minds. No step in biological 

 progress at the present time could be a greater contribution to 

 human knowledge. 



We have now completed our survey of the field of evolution. 

 We have considered the growth of the idea from its earliest concep- 

 tion, the evidences of relationship in existing organisms, the 

 evidences of evolution drawn from living things and from the 

 sciences of geologj^ and palaeontology. We have learned of the 

 contributions of genetics to our understanding of the transmission 

 of characters from generation to generation. Finally we have 

 examined the theories which have been proposed to explain the 

 association of all of these facts in the production of the organisms 

 which populate the earth. And we have found that in spite of 

 his wonderful accumulation of facts, man still knows very little 

 of the forces which have placed him where he stands today. 



The failure of existing theories of evolution shows very clearly 

 that something has been amiss in the past treatment of the subject. 

 It is difficult to avoid the prejudices of past training. If we bear 

 in mind that we are neither Neo-Darwinians nor Neo-Lamarckians, 

 and that we have no predilection for continuity of the germ plasm 

 or the inheritance of acquired characters, we can hope to learn 

 still more of evolutionary processes. If we remember that we are 

 merely scientists, seeking for clear information and logical deduc- 

 tions, we find that there is a firm and satisfying basis of fact in 

 modern biology for the examination of the problems of evolution, 

 and we can conclude in no more satisfactory way than at this 

 threshold of the evolution of the future. 



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