LUTHER BURBANK 



unchanged, true to their racial type, generation 

 after generation, for untold centuries. It repre- 

 sents an old, fixed, conservative stock. No one 

 knows how to make it change, except within the 

 narrowest of limits. 



There is a very essential time element, then, 

 that is instrumental in determining the fixity or 

 variability of a race of plants. A plant that has 

 been bred true to a given type for long periods 

 of time, as is the case with the generality of wild 

 plants, will breed substantially true from seed, 

 and as a rule will maintain its racial type even if 

 transplanted to new surroundings. 



But, on the other hand, the generality of 

 cultivated plants are of mixed ancestry. Man has 

 attempted within recent generations, to change 

 them and adapt them to his needs. He has 

 constantly been hybridizing them, or placing 

 them under conditions that resulted in their 

 hybridization through the visits of bees; and he 

 has selected and cultivated the individual speci- 

 mens that tended to vary, and thus has fostered 

 the habit of variability rather than that of fixity 

 of character. 



In the case of most orchard fruits, as we have 

 had occasion to observe more than once, so many 

 strains are blended that propagation from seeds 

 is quite out of the question; unless, indeed, it be 



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