The Evolution of Organisms 153 



have! We have only begun to enter upon our 

 Kingdom.^ 



Factors in Evolution. — When we pass from the 

 modal formula of organic evolution to consider 

 how the process works, we pass from clearness to 

 perplexing uncertainty. Huxley's saying, " If the 

 Darwinian hypothesis (of Natural Selection) were 

 swept away, evolution would still stand where it 

 was," has puzzled some, but it obviously means 

 that while all research strengthens our confidence 

 in the general idea of organic evolution, we are 

 very uncertain as to the actual mechanism. The 

 fact of evolution forces itself upon us; the factors 

 elude us. There can be no dogmatism. The 

 consistent evolutionist knows that he and his in- 

 terpretation, like the world which he studies, are 

 within the sweep of the evolution process, have 

 been evolved, and are still evolving. He never 

 claims finality of interpretation, for that would 

 be self-contradiction. 



Variations: The Raw Materials of Progress. — The 

 first great question concerns what may be called 

 the raw materials of progress — the origin and 

 nature of those organic changes or variations on 

 which the possibility of evolution depends. Dar- 

 win started from the broad fact that variability 

 exists, illustrating it chiefly from domesticated 

 animals and cultivated plants; he postulated an 

 1 See Sir E. Ray Lankester's "Kingdom of Man," 1907. 



