XX. 



LIEBIG'S MINEEAL THEOEY. 



THE only office of the soil, aside from holding 

 the plant in place, and furnishing a supply of 

 moisture, is to supply the ash elements of plants, 

 that is, those materials which remain after the 

 plant is burned. 



2. The office of these mineral or ash elements 

 is to enable the plant to assimilate the organic ele- 

 ments which it derives from the air; the assimila- 

 tion of the carbo-hydrates (starch, woody fibre, 

 etc.) being dependent upon the presence of the 

 alkalies, especially potash and soda; and the 

 capacity of the plant to form the albuminoids 

 (gluten, etc.) being in like manner determined by 

 the presence of phosphates. 



3. That the fertilizers necessary for the pro. 

 duction of a given crop could be determined in 

 character and amount by burning the entire plant 

 and analyzing the ash. 



4. Therefore, if the proper mineral elements 

 were supplied to the soil in suitable quantities, no 

 other fertilizers would be needed. Farm-yard 

 manure, for example, if burned, and the ashes 



(118) 



