206 LUTHER BURBANK 



About half of them, it will be recalled, did not 

 present the crinkled leaf to any extent and were 

 at once eliminated. 



And the other half exhibited the character in 

 varying degree. 



Indeed, no two of them were precisely identi- 

 cal, so we were justified in the conclusion that no 

 two pairs of pollen grains and ovules brought 

 precisely the same combination of hereditary 

 factors together. 



When we consider the matter in this light, it 

 will be evident that all pollenizing experiments 

 are in a sense hybridizing experiments in one 

 degree or another, inasmuch as they all of neces- 

 sity bring together pollen grains and ovules that 

 vary somewhat, even if only in very minor de- 

 gree, in their hereditary factors. 



But it remains true and indeed is too ob- 

 viously true to require comment that the case 

 of the pollen grains united with pistils on 

 flowers of the same plant (the case, that is to say, 

 of the Heuchera under consideration) is that in 

 which there is the least possible degree of varia- 

 tion between the two sets of elementary factors 

 that are combined. 



Therefore this process of so-called inbreeding 

 introduces the least possible disturbing elements, 

 and gives the largest probability of the reproduc- 



