CHAPTER VIII 



DARWINISM AND HOLISM 



Summary. — Darwin's conception of Organic Descent and his 

 formulation of its laws were the beginning of one of the most far- 

 reaching revolutions in human thought. Holism gives a new view 

 of one of the Darwinian factors, and extends the scope of Evolu- 

 tion beyond the purely organic domain. 



Darwin traced Organic Descent to the interwoven effects of two 

 factors: an inner creative factor, Variation, operating sponta- 

 neously and somewhat mysteriously inside organisms and modify- 

 ing their hereditary structures and functions in very slight degrees; 

 and an external factor. Natural Selection, which operates selec- 

 tively on these slight variations, weeding out those organisms 

 whose variations were less suitable to their environment, and 

 leaving the organisms with suitable variations to multiply and 

 develop. By continuous summation of small useful variations 

 through many generations definite specific characters would in 

 time be achieved and new species arise. 



Darwin laid most stress on the factor of Natural Selection; on 

 Variation he was vague and hesitating, but there is little doubt 

 that he included not only inborn variations but individually ac- 

 quired modifications among the elements which ultimately become 

 specific characters. Thus all the multitudinous forms of life 

 would in the end be moulded by both factors into very close con- 

 formity and adaptation to their conditions of life. 



The great Darwinian conception has been somewhat blurred by 

 later developments, in which attention has been concentrated on 

 the factor of Variation rather than on Natural Selection. First 

 Weismann denied the transmissibility of acquired characters, and 

 thus made it difficult to understand how organisms through their 

 experience and habits of life become gradually fitted and adapted 

 to their environment. Then De Vries eliminated all small varia- 

 tions from the account and attributed all specific advance to large 

 well-marked "mutations" occurring very occasionally. This made 

 it still more difficult to understand slow age-long adaptation, for 

 instance, to habitats and ecological conditions. Finally, the Men- 

 delians or Geneticists have developed the conception that in or- 

 ganisms there are well-marked stable unit-characters whose com- 



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