52 



ON INCREASING THE GROWTH 



eral principle, the leafy parts and roots of plants 

 chiefly require, besides nitrogen, alkalies and earths 

 (potash and lime) for their full development ; the 

 seeds, again, phosphoric acid and nitrogen. To 

 this conclusion the leaves of the beet form a merely 

 apparent exception, because they were examined 

 in a green or semi-matured period of their growth. 

 In this condition they of course contain the mate- 

 rials from which the root, and, at a still later period, 

 the blossom and seed, are to be formed. When 

 completely matured, they contain less phosphoric 

 acid and less nitrogen. In this state of things it will 

 no longer seem strange that many manures, as expe- 

 rience demonstrates, occasion more especially the 

 growth of stalks and leaves ; and others an abundant 

 production of seed. 



What are the constituent elements contained in ma- 

 nure ? This is the first and most important question 

 the chemist has to answer, before he can furnish dis- 

 tinct information to the inquiries proposed by the 

 practical agriculturist : How does manure operate ? 

 How quickly does it act ? How long does its action 

 continue ? What is its worth ? etc., etc. Manure 

 operates only by means of the chemical substances 

 it contains ; these, therefore, must be accurately as- 

 certained, before any exact intelligence can be afford- 

 ed by the chemist as to its action and effects. Were 

 this the whole inquiry, it might be conclusively set- 

 tled ; for chemistry is now so far advanced, as to be 

 able to detect and define these elements even to a 



