86 LUTHER BURBAXK 



It must supply nourishment to the multitudi- 

 nous cells that make up its root and stem and 

 branches, which, as we have seen, are quite in- 

 capable of extracting nourishment from the 

 crude salts in solution that they are constantly 

 transporting. 



But, incidentally, in manufacturing food for 

 its own cells, the plant is producing a supply of 

 food that will be available for the sustenance of 

 animal cells also. Thus the entire animal world 

 may be said to be a vast parasitic colony as ab- 

 solutely dependent upon the vegetable colony 

 for its essential food supplies as any other para- 

 site is dependent upon its host. 



When we consider the matter in this light, 

 it is pretty obvious that about the most interest- 

 ing thing in the world, from the standpoint of 

 animal economy—which of course includes hu- 

 man economy — is the wonderful laboratory or 

 factory of the plant where alone is effected the 

 transformation of the crude inorganic elements 

 into such combinations as are available for the 

 sustenance of life. 



When we reflect that the plant laboratories 

 in which this wonderful and vitally essential 

 transformation is effected are chiefly located in 

 the leaf of the plant, it appears that the thought- 

 ful person must regard this structure — the most 



