LUTHER BURBANK 



only the races that showed this adaptability of 

 habit. Thus the common race of spring-bearing 

 rhubarb, as we know it, was developed. 



But the latent capacity to bear at all seasons — 

 to live a fully rounded life throughout the 

 year — which may be considered the normal and 

 inherent propensity of all living things, and which 

 is observed to be the habit of tropical plants in 

 general, was never altogether lost. Submerged 

 generation after generation and century after 

 century, the hereditary factors that make for per- 

 petual growth were still preserved, capable, under 

 changed conditions, of being resuscitated and of 

 making their influence manifest. 



The changed conditions came, in case of the 

 rhubarb, when the plant found itself in the new 

 environment of California. 



New soil, new atmosphere, new climate — all 

 these are stimulative. Then successive gener- 

 ations of the plants were bred from seeds, and 

 we have already seen that the mixture of strains 

 thus effected tends to have a disturbing influence 

 on the germ plasm, permitting new combinations 

 of characters and resulting in the development of 

 new forms. 



We saw this in the case of the Shasta daisy 

 and very notably in the case of the hybrid wal- 

 nuts. We shall note the same thing again and 



[192] 



