ORGANIC EVOLUTION JORDAN 325 



than traits which are plainly adaptive. The slight traits which 

 mark races are in themselves not obviously valuable in the struggle 

 for existence. 



Moritz Wagner, the pioneer in this line of investigation, showed 

 plainly that in the study of the evolution of any form we need to 

 know where its has lived, what it did, how it was bounded, and what 

 was its relation to other forms, geographically as well as morpho- 

 logically. His work, a most necessary supplement to that of Dar- 

 win, has never received the attention it deserves. This is due in part 

 to the fact that most investigators do not travel. They know little 

 of animal or plant geogra]Dhy at first hand. They have had nothing 

 to do with species as living, varying, reproducing, adapting, and 

 spreading groups of organisms. Another reason lies in Wagner's 

 attitude of opposition to Darwinism. For natural selection he sub- 

 stituted separation, " rdumliche Sonderung^'' denying altogether the 

 potency of the former factor. He saw the two as competing, not coop- 

 erating elements, and thus threw on isolation the impossible task of 

 accounting for adaptation. One need not ascribe to natural selec- 

 tion the '"'"AllmacJit " which some Neo-Darwinians have claimed for 

 it, yet on the other hand those who reject it as a factor in organic 

 evolution give no rational explanation of the universality of adaptive 

 organs and adaptive traits, no clue to the most universal characters of 

 organisms in general. 



Certain writers urge that neither selection nor isolation are factors 

 in evolution, but rather elements in species forming, a process de- 

 fined as something distinct from evolution. They say that these 

 obstacles in the stream of life only help to split on-moving groups 

 of organisms into different categories, while the impulse to forward 

 movement is internal and the changes of evolution proper affect 

 groups as a whole, and are not concerned with dividing them into 

 species. 



Such a view may be questioned on two gi'ounds; it is untrue as 

 to facts, or else merely a matter of words. We know nothing of 

 evolution in vacuo, of change in life unrelated to environment. All 

 forms of life are split up into species, with adaptation to external 

 conditions visible in every structure. We know of no way in which 

 organisms become adapted to special conditions except by the pro- 

 gressive failures of those which do not fit. No organism has escaped 

 or can escape the grasp of selection. In like manner, the world being 

 full of physical barriers, no organism escapes biological friction 

 which prevents uniformity in breeding. There must be some degree 

 of '"'' roMmliche Sondei^ng^'' even in a drop of water. As Wagner 

 truthfully observes : " Ohne Isolirung keine Arten^ 

 76041—26 22 



