i] Introductory 3 



satisfied. The Origin was published in 1S59. During 

 the following decade, while the new views were on trial, 

 the experimental breeders continued their work, but before 

 1870 the field was practically abandoned. 



In all that concerns the problem of species the next 

 thirty years are marked by the apathy characteristic of an 

 age of faith. Evolution became the exercising-ground of 

 essayists. The number indeed of naturalists increased ten- 

 fold, but their activities were directed elsewhere. Darwin's 

 achievement so far exceeded anything that was thought 

 possible before, that what should have been hailed as a 

 long-expected beginning was taken for the completed work. 

 I well remember receiving from one of the most earnest 

 of my seniors the friendly warning that it was waste of 

 time to study variation, for '' Darwin had swept the field." 



Parenthetically we may notice that though scientific 

 opinion in general became rapidly converted to the doctrine 

 of pure selection, there was one remarkable exception. 

 Systematists for the most part kept aloof. Everyone was 

 convinced that natural selection operating in a continuously 

 varying population was a sufficient account of the origin of 

 species except the one class of scientific workers whose 

 labours familiarised them with the phenomenon of specific 

 difference. From that time the systematists became, as 

 they still in great measure remain, a class apart. 



A separation has thus been effected between those who 

 lead theoretical opinion and those who by taste or necessity 

 have retained an acquaintance with the facts. The con- 

 sequences of that separation have been many and grievous. 

 To it are to be traced the extraordinary misapprehensions 

 as to the fundamental phenomena of specific difference 

 which are now prevalent. 



If species hacl really arisen by the natural selection for 

 impalpable differences, intermediate forms should abound, 

 and the limits between species should be on the whole 

 indefinite. As this conclusion follows necessarily from the 

 premisses, the selectionists believe and declare that it 

 represents the facts of nature. Differences between species 

 being by axiom indefinite, the differences between varieties 

 must be supposed to be still less definite. Consequently 

 the conclusion that evolution must proceed by insensible 



