False Atavism 187 



sort to another, and separation by great dis- 

 tances would be required to avoid this source of 

 impurity. Unfortunately the arrangements 

 and necessities of large cultures make it impos- 

 sible to isolate the allied varieties from each 

 other. 



From a theoretical point of view the origin 

 of these impurities is a highly important ques- 

 tion. If the breeders' atavism is due to crosses, 

 and only to this cause, it has no bearing at all 

 on the question of the constancy of varieties. 

 And the general belief, that varieties are dis- 

 tinguished from true species by their repeated 

 reversion and that even such reversibility is the 

 real distinction of a variety, would not hold. 



For this reason I have taken much trouble 

 in ascertaining the circumstances which attend 

 this form of atavism. I have visited a number 

 of the leading nurseries of Europe, tested their 

 products in various ways, and made some ex- 

 periments on the unavoidable conditions of 

 hybridizing and on their effect on the ensuing 

 generations. These investigations have led me 

 to the conclusion, that atavism, as it is gener- 

 ally described, always or nearly always is due 

 to hybridization, and therefore it is to be con- 

 sidered as untrue or false atavism. 



True atavism, or reversion caused by an in- 

 nate latent tendency, seems to be very rare, 



