84 LUTHER BURBANK 



utilizes the excess of carbonic acid are in abey- 

 ance, that the fact of the close analogy between 

 vegetable protoplasm and animal protoplasm as 

 to the ingestion of oxygen and the giving out of 

 carbonic acid as waste was demonstrated. 



Now it is known, however, that the protoplasm 

 of a plant cell, as it exists in the root and trunk of 

 a tree, for example, and indeed in any part of a 

 plant where there is no green matter, not only 

 functions in the same way as the protoplasm 

 of animal cells, in regard to absorbing oxygen 

 and giving out carbonic acid, but that the two 

 have precisely the same food habits in general. 



The average plant cell, as it exists in the root 

 or stem of the plant, is in precisely the same 

 position as the cells of an animal, in that it can 

 secure nourishment only from food that has been 

 prepared in a particular way. 



It can no more take a crude solution of mineral 

 salts and extract nourishment from them than 

 can the animal cell. 



All the necessary constituents that go to make 

 up the best food may be present, but neither the 

 plant protoplasm nor animal protoplasm can 

 use these constituents unless they have been com- 

 pounded in a unique and extraordinary way. 



But when we consider the matter one stage 

 farther we come upon this vital difference: the 



