CONCLUSION 



I CONCLUDE the first part of this book with the Address 

 following, not only because it contains some of the most 

 important of the views here expounded, but especially because 

 it expresses the fundamental conception from w^hich all my 

 views arise — the doctrine of the unity of organic nature. 



My view of the causes of the origin of species is nothing 

 but the logical application of that conception to the explana- 

 tion of the manifold variety of the living world. It miglit be 

 replied that this conception equally influences the minds of all 

 who endeavour to explain the origin of species by the gradual 

 modification of organisms. It is true that no evolutionist at 

 the present day contests the fact that varieties, species, genera, 

 families, etc., more or less plainly pass by transitions into one 

 another, and that these are in the last result artificial concep- 

 tions. Indeed, it is the most confident disciples of the doctrine 

 of evolution, of Darwinism, who most loudly complain, not 

 merely of the manufacture of species, but particularly tliat 

 systematists regard varieties, not as a kind of transition from 

 species to species, but as a comparatively unimportant devia- 

 tion from the established type of the species. Nevertheless, 

 in the more recent attempts to explain evolution, tliis principle 

 of the unity of organic nature has been more or less dis- 

 regarded. These attempts show that transmutationists make 

 no less distinction between variety and species tlian the 

 systematists. For the former recognise that certain influences 



