CHAPTER IV 

 FACTORS AND MECHANISM OF EVOLUTION 



Even in the latest and maturest formulations of scientific research, 

 the dramatic tone is never lost. The causes at work are conceived 

 in a highly impersonal way, but hitherto no science has been content 

 to do its work in terms of inert magnitude alone. Activity continues 

 to be imputed to the phenomena with which science deals, and activity 

 is, of course, not a fact of observation but is imputed to the phenomena 

 by the observer. Epistemologically speaking, activity is imputed to 

 phenomena for the purpose of organizing them into a dramatically 

 consistent system." THORSTEIN VEBLEN. 



THERE is to-day no doubt in our minds of the truth, the 

 actuality, of descent. It is not the theory of descent: it is the 

 fact, the law, of descent, of which we talk and write. Organ- 

 isms are blood-related: they are transformed, descended from 

 one another. This, which is the common knowledge of present- 

 day post-Darwinian science, was the belief of many naturalists 

 even before the days of Darwin. " From the Greeks to Darwin " 

 was not all darkness nor complete freedom from taint of the 

 "pernicious evolution doctrine." Goethe, Erasmus Darwin, 

 Lamarck, to mention only familiar names, were evolutionists: 

 they believed in the transmutation of species, believed in descent. 

 But it was Darwin who gave the waiting naturalists substantial 

 and satisfactory reasons for the beliefs that were in them; who 

 gave them strength to have the courage of their convictions. 



While Darwinism, in our present-day use of the name, is 

 not synonymous with descent and evolution, but is the name 

 of a causomechanical explanation of it, or a group of causal 

 factors, yet it might justifiably be more broadly used, and held 

 still to mean, what it certainly did to the world generally for a 

 good many years after the "Origin of Species" appeared, the 



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