29O COOK 



highest. For half a century this probability that the world of 

 organism has come into existence through long series of changes 

 has been the most prominent idea before the scientific public, 

 but we have not yet accepted fully the simplest purport of the 

 idea of evolution and asked ourselves the direct question : By 

 what mode or manner of motion is evolution accomplished? 



Some have assumed that the evolutionary causes are resident 

 in the environment, and others that they exist in the organisms 

 themselves. A third alternative is here considered, that evolu- 

 tion arises from the association of organisms into interbreeding 

 groups, or species. Species, in this interpretation, appear to 

 contain the causes of evolution, instead of evolution affording 

 the explanation of species. 1 



The first result of Darwin's attempt at establishing the general 

 idea of evolution on a basis of relation to concrete facts was a 

 long and bitter controversy with those who clung to the older 

 theory that the species of nature had arisen by separate creative 

 acts. Biological science made good its escape from the house 

 of theological bondage, but its controversial sins have con- 

 demned it to forty years of wandering in the wilderness of 

 species-formation and environmental adjustments, desert regions 

 often very interesting in themselves, but remote enough from 

 the fertile fields of evolution. 



It may well be doubted whether any student of nature, if 

 asked the direct question, whether species are normally at rest 

 or normally in motion, would definitely and dogmatically hold 

 to the static assumption. This appears to have been made quite 

 unconsciously, in the great majority of cases, or taken entirely 

 for granted. Nevertheless, all the current theories and methods 

 of investigating evolutionary problems are based on this assump- 

 tion of normally stationary species. The influence of the 

 doctrine of special creation was too strong to be overcome at 

 once, even by biologists who were very active in opposing its 

 theological implications. 



The idea of environmental causation of evolution has com- 



1 Cook, O. F., 1904. Evolution not the Origin of Species, Popular Science 

 Monthly, for March. Reprinted with additions in the Smithsonian Report for 

 1904 under the title, The Evolutionary Significance of Species. 



