286 COOK 



In popular discussions it often happens that the best and most 

 important data are left in the background because the public is 

 not ready to appreciate them. Thus Huxley, who rendered the 

 most valiant service in the defense of Darwinism as a theory of 

 environmentally caused evolution, also wrote this discriminating 

 statement : 



" It is in the recognition of a tendency to variation apart from 

 the variation of what are ordinarily understood as external con- 

 ditions that Darwin's view is such an advance on Lamarck." 



To have secured popular appreciation for these nonenviron- 

 mental variations at that time was manifestly impracticable. Even 

 after fifty years their existence is still generally unrecognized. 



The credit of turning the scientific world to the study of evo- 

 lution will always belong to Darwin and Huxley, but the fifty- 

 years canvass which has now been given to the Darwinian 

 theory of environmental action upon normally stable species has 

 yielded nothing of moment. Huxley's appreciation of the 

 advance of Darwin beyond Lamarck has not been shared by 

 the evolutionary public, and the result has been a general 

 reaction toward pre-Darwinian conceptions, and even to some 

 which Darwin himself considered and dismissed. 1 



Perhaps the time has come to renew the consideration of the 

 problem from the kinetic standpoint and to take into account 

 again the normal diversity of descent and the normal inter- 

 breeding of the members of species. These facts have re- 

 mained veritable stones of offense for the builders of static 

 theories of environmental causation, but they can now be util- 

 ized as foundations of a new and more commodious structure of 

 evolutionary thought. 



4. MODES OF EVOLUTIONARY MOTION. 



The law of evolution which declares that organic nature has 

 come into existence through a connected and gradual process, 

 and not through millions of separate creations of species, now 

 commands the practically universal adherence of biologists, and 



1 " And again, after mentioning the frequent, sudden appearances of domestic 

 varieties he speaks of ' the false belief as to the similarity of natural species in 

 this respect.'" See Mivart, 1S71. Genesis of Species, 36. 



