LUTHER BURBANK 



manufactured in the leaves of the plant must be 

 sent back down the stem of the plant to be depos- 

 ited, in case of a tuber-forming plant like the 

 potato, in connection with the roots in the ground. 



It follows, then, that the tomato plant, even 

 though its source of supply was the root system 

 of a potato, merely gained from these roots part 

 of the raw inorganic materials with which its 

 leaves were to manufacture the special compounds 

 that go to make up a tomato. Inasmuch as the 

 tomato leaves were themselves unmodified, there 

 was no reason why their product, the tomato, 

 should be greatly modified. 



In receiving its supply of raw material from a 

 foreign root, the tomato top was in no different 

 condition from the ordinary cions in a fruit 

 orchard, which, as we have seen, are habitually 

 grafted on roots or branches of a foreign species. 



But the case of the potato tubers is obviously 

 quite different. Their substance is made up of 

 material that came originally, to be sure, in part 

 from material gathered by potato roots; but this 

 material had traveled up to the leaves of the 

 tomato plant and had there been transformed; so 

 when it returned to be deposited and form tubers 

 it was a tomato compound and not a potato 

 compound. 



It was not absolutely different in material from 



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