84 EVOLUTION. SOCIAL AND ORGANIC 



of variation that the Neo-Lamarckians and 

 the Weismannians fought their battle, the for- 

 mer insisting, as we have seen, that variation 

 was caused by the hereditary transmission of 

 acquired characters, while Weismann main- 

 tained that variation arose solely through the 

 combining of two portions of differing germ- 

 plasm contributed by two different individu- 

 als, and producing a new individual unlike 

 either, — a "variation" from both. While what- 

 ever there was of victory fell to Weismann, 

 neither side has experimentally proven its 

 case, and we are still in the dark as to the 

 "causes of variation." Our ignorance is still 

 cloaked in the convenient word "spontane- 

 ous ;" to Darwin's "spontaneous variation" we 

 now add DeVries' "spontaneous mutation." 



It is another tribute to Darwin's caution 

 and insight that he recognized the possibility 

 of variations arising either suddenly, as De 

 Vries asserts they do, or gradually as DeVries 

 denies. 



Not only did Alfred Russell Wallace seek 

 to limit the operation of natural selection in 

 certain fields, in order to make room for his 

 spiritualist theories — an adventure which 

 failed dismally — but he denied the sudden 

 appearance of new species or sub-species, 

 thereby restricting Darwinism, as he under- 



