vm DARWINISM AND HOLISM 193 



third place, a large very marked inherited change is called 

 a mutation. Any inherited change large and marked enough 

 to constitute a new variety or species is a mutation. 



Now I think it is beyond question that according to 

 Darwin's view all three forms of change — modifications, 

 variations and mutations — were useful and operative in 

 the ultimate production of new species. Modifications due 

 to individual use or disuse he certainly pressed into the 

 service of his scheme of Evolution; and although it is not 

 quite clear how far other modifications were similarly treated 

 by him, it follows from the above quotation as well as from 

 other passages in his works that variations due "to the 

 indirect or direct action of the conditions of life," in other 

 words, alterations affecting the individual life, could, to an 

 extent never clearly defined by him, avail for the production 

 of new species. As regards mutations, while he gave reasons 

 for disbelieving in great and sudden changes as the ordinary 

 rule of evolution, it can certainly not be said that he excluded 

 them. His view was that the slow and gradual summation 

 of small modifications and variations continuously conserved 

 or kept going by Natural Selection would, and in fact did, 

 in the course of many generations amount to a sufficiently 

 large and marked change to constitute a new type or species. 

 The continuous summation of the effects of use and disuse 

 and the other conditions of life, as well as the accidental 

 inherited variations which were of a more mysterious origin, 

 would necessarily co-operate with Natural Selection in 

 bringing about the close adaptation of the species to its 

 environment. The result was the vast and intricate system 

 of adaptations and co-adaptations, of harmonious adjustment 

 between Nature and organic life, ramifying through the 

 infinite details of the web of life which we see in Nature. 

 Thus Evolution was explained, thus all the fine adjustments 

 and adaptations in Nature were explained. Only a very 

 long time was required for the infinitesimal calculus of 

 Natural Selection to produce the various results, and that 

 requirement was conceded by the astronomers and geologists. 

 Darwin's view seemed very well to fit in with the fossil 



