CH. XIV] GENERAL DISCUSSION 169 



The theory of natural selection, holding as it did that every- 

 thing was gradually acquired, went to show that evolution must 

 be gradual and continuous from one structure to its successor of 

 different form, and this soon led to difficulty. The facts of 

 economic botany (pp. 8, 89) among others, though dismissed as 

 unimportant since they did not favour natural selection, showed 

 that there was much discontinuity in evolution, and Bateson's 

 work (1) showed the same thing. 



The continuous small fluctuating (infinitesimal) variations upon 

 which Darwin chiefly relied were not fully hereditary (p. 10); 

 they were not differentiating, but simply up and down in the 

 same character, nor were they irreversible; and they could 

 not be accumulated beyond a certain point (p. 10). They could 

 all but never be found to show adaptation, whilst the differences 

 became more and more marked, and less and less adapta- 

 tional the higher that one went from species to family, this 

 illustrating the principle that we have termed the divergence of 

 variation (p. 74). Species, again, usually showed several points 

 of difference which were unconnected with one another so far as 

 anyone could see, and it was very hard to see how selection could 

 deal with so many. Species also proved to be mostly local in the 

 big or "successful" genera, so that their adaptation must have 

 been generic, and it was very hard to understand how this could 

 have been the case. If it were so, natural selection, working 

 upwards from the species, could hardly explain it. If all specific 

 characters were correlated, then the greater portion of evolution 

 did not show the effects of natural selection (p. 11). It was 

 almost impossible to see how gradual selection could pass the 

 rough and ready line of distinction between species, the fact that 

 they are almost always more or less mutually sterile. No transi- 

 tion stages, again, were to be found among the fossils, though one 

 would have expected to find such upon a theory that was based 

 upon the separation of genera and families, to say nothing of 

 species, by the continual destruction of transitional forms on 

 account of their inferiority to the more perfect. Nor could one 

 find among the fossils any indication of the gradual formation of 

 existing families, etc. These seem to appear already fully de- 

 veloped, and in widely separated sections of the classification of 

 flowering plants. 



Evolution could only go on if the right variations were to 

 appear; natural selection would kill out any that were harmful, 

 and would be indifferent to any that showed neither value nor 



