EVOLUTION NOT THE ORIGIN OF SPECIES. 445 



EVOLUTION" NOT THE OEIGIN OP SPECIEsI" ' ' ' ''^ '' 



By O. F. cook, 

 u. s. department of agkicultuke. v 



TT is a misfortTine frequently lamented that new truth, the most 

 -^ precious attainment of each generation, is also the most unwelcome. 

 We do not hasten to sweep out our stock of laboriously collected ideas, 

 even after the worthlessness of the assortment has been declared. This 

 conservatism of vested intellectual interests not only postpones the 

 utilization of the results of scientific inquiry, but it has an even worse 

 effect when it impedes further investigation and warps our perception 

 of facts. 



The great obstacle in the popularization of the fundamental and 

 obvious biological fact of evolution was the theological dogma of the 

 separate creation of species, and toward the overthrow of this the argu- 

 ments of Darwin and his immediate followers were, of necessity, di- 

 rected. After four decades the debate upon the general question may 

 be said to have closed. The thoughtful public believes that species 

 were not made like cakes by the baker, but that the diversity of organic 

 nature has been attained by gradual changes and transformations, a 

 process commonly thought of as 'evolution.' As soon, however, as we 

 pass into the field of biology proper, and seek to know the nature and 

 causes of this process, all unanimity of opinion vanishes. The fact of 

 evolution is no longer doubted, but biologists are still writing thousands 

 of pages annually in support of the most diverse and contradictory in- 

 terpretations of evolutionary phenomena. 



In spite of the external simplicity of the idea, evolution affords 

 extremely complex and elusive problems, and in addition to the inherent 

 difficulty of these, discussion is still cumbered with the original ter- 

 minology. Vast quantities of arguilientation wasted in attempting to 

 convince theologians that they did not know how species were made 

 are already forgotten, but a more troublesome legacy remains, in that 

 the words and ideas upon which attention became focused during that 

 struggle still darken our views of biological problems. 



Evolutionists, too intent on a practical explanation of the diversity 

 of species, seized upon the idea that organisms become adapted to en- 

 vironment, and disregarded the more fundamental fact that species are 

 not by nature stationary, but have an independent motion of their own. 

 This oversight brought us the impossible task of explaining how ex- 

 ternal conditions produce evolutionary changes, and prevented the per- 



