LUTHER BURBANK 



recombine them variously by hybridizing, and thus 

 to develop new races from the old stock. 



When, however, the plant developer, through 

 his hybridizing experiments, brings together 

 groups of characters in which the old guards, so to 

 speak, that have control over the fundamental 

 characters are in conflict, no union is possible. 



Either fertilization will not take place, or the 

 offspring will be sterile. Only within narrow lim- 

 its, and as regards the new and relatively unes- 

 sential characters, can there be diversity or, at 

 most, the accentuation of old characters. 



Such an accentuation, for example, occurs, we 

 may suppose, in the case of the hybrid walnuts, 

 which take on gigantic growth. Both Persian wal- 

 nut and California walnut have in their germ 

 plasm the hereditary factors of large groups of 

 remote ancestors of the Mesozoic era, when gigant- 

 ism was the fashion, but these factors have for 

 long generations been subordinated by newer ones 

 born in a less favorable era. Now, however, 

 hybridzation brings the two strains together, and 

 the two dominant groups of factors for slow and 

 relatively dwarfed growth, in some way mask or 

 neutralize each other, enabling the earlier groups 

 to make their influence felt. 



And here, as we have seen, the factors for 

 growth that have thus been rudely disturbed as to 



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