F0R.MAT10X OF STRAW. 199 



(i. e. the leaves, stalks, and roots) is formed from the 

 albumen of the cereal seeds, that is, from the constituent 

 elements of the seeds ; and, further, that these parts of 

 the plant are the organs for the reproduction of these 

 same seed constituents. 



The production of the straAv always precedes the for- 

 mation of the grain ; and that portion of the seed ele- 

 ments which serves to form the organs of the plant can- 

 not be used to make seed : or, the more seed-constituents 

 are turned into straw-constituents within the appointed 

 time of growth, the fewer will remain at the close of that 

 period for the formation of seed (see p. 51). 



Before the period of flowering, all the seed-constituents 

 go to form straw ; after that period, a division takes place. 



Therefore, if all other conditions of soil and weather 

 are equally favourable, the quantity of straw will depend 

 upon the amount of seed-constituents needed for the 

 formation of straw. 



The quantity of corn depends upon the residue of seed- 

 constituents in the whole plant, which are no longer 

 required for the multiphcation and enlargement of leaves, 

 stalks, and roots. 



Let K represent that portion of the corn-constituents 

 that may be formed into seed ; aK the other fraction of 

 the same substances, which remain as constituents in the 

 straw ; and St the otlier constituents comprised in the 

 straw : so that 



K^ (phosphoric acid, nitrogen, potash, lime, magnesia, iron) 

 «K = a fraction of K 

 S^=(silicic acid, potash, lime, magnesia, iron) 



then the nutritive substances which the [)lant has absorbed 

 from the soil, may be thus expressed : — 



(K-HaK SO- 



