236 COOK 



lutionary connection between the origination of species and the 

 origination of marks or characters by vvhicli species may, or 

 may not, be distinguished. Species may be quite distinct and 

 may yet offer precious few diagnostic marks. On the otlier 

 hand, one and the same species may manifest so much diversity 

 of characters that numerous species could be distinguished were 

 it not for the intergrading forms. 



Though many have taken it for granted, nobody has show^n 

 that there is any relation between the origination of characters 

 and the origination of species. Species do not have to be 

 originated to originate characters, nor characters to originate 

 species. Nor has it ever been shown that the origination of 

 species has any causal relation to evolution. Species originate 

 by isolation, that is, by the subdivision of older species. The 

 groups attain differential characters after isolation, in the same 

 way that characters would have continued to be attained if the 

 original species had not been subdivided. The origination of 

 the species does not cause the origination of characters, nor 

 does the origination of characters cause the origination of species. 



Nor is there any necessary relation between the discontinuity 

 of characters which distinguish species and the discontinuity of 

 character-diversity among the members of the same species. 

 Species might differentiate in the most gradual manner, but 

 having once differentiated their characters would be discontinu- 

 ous, for this is the taxonomic criterion of specific differentiation. 

 Nevertheless, discontinuous variations might spread gradually 

 through a species and transform it. The discontinuity of the 

 variations would not break the continuity of the evolution of the 

 species. Discontinuous variations make the mutation theory 

 abstractly conceivable, but they do not afford any evidence that 

 it is the true method of evolution. 



The origin of species is not evolution ; evolution is the chang- 

 ing of characters in species. Not all changes of characters 

 are evolution, but only changes of characters in species, or 

 changes of the same nature as changes in species. Mutative 

 changes of characters in narrow-bred domesticated varieties, 

 and the strict Mendelian polarity of expression of such mutative 

 differences, are not phenomena of evolution, but of degenera- 



