THE SUM OF HIS WORK 



hybrids might afford a final guide, was not without 

 its practical value, and made perhaps not unnat- 

 ural appeal to the more or less befuddled classi- 

 fiers themselves. 



And so long as cross-fertilization was effected 

 solely between forms of animal or plant life that 

 were found growing wild in the same region, and 

 were obviously not very distantly related, it was 

 hardly possible to present evidence of the fertility 

 of hybrids between true species that would be 

 convincing. 



The more fully the biologist grasped the phil- 

 osophical idea that the word "species" is after all 

 only a convenient formula to apply to a given form 

 rather for convenience of nomenclature than as 

 representing true and permanent distinctions, the 

 more logically might he grasp the dictum that any 

 two forms that can interbreed and produce fertile 

 offspring are not entitled to rank as species, even 

 in the modified view of the meaning of the word 

 species that the evolutionary doctrine has intro- 

 duced. 



Yet after all there is a certain tangibility about 

 the idea connoted by the word species that the 

 practical classifier cannot ignore. The blackberry 

 and the raspberry, for example, are so obviously 

 different in many really essential parts of their 

 structure that to deny them specific individuality 



[177] 



