COMPOSmOK IN SUCCESSIVE STAGES. 329 



in the roots, which now are transferred to the fruit and 

 foliage, and maintain the growth of these parts after 

 their power of assimilating inorganic food (OOj, H2O, 

 NH3, NjOs) is lost. 



The following statement exhibits the absolute average 

 daily increase of Carbon, Hydrogen, Oxygen, Nitrogen, and 

 Ash, during the several periods (lbs. per acre) : 



Table 'KI.—Bretschneider. 



Turning now to Arendt's results, which are carried 

 more into detail than those of Bretschneider, we will 

 notice: 



A. — The Relative {percentage) Composition of the 

 Entire Plant and of its Parts* during the several 

 periods of vegetation. 



1. Fiber] is found in greatest proportion — 40 per cent 

 — in the lower joints of the stem, and from the time 

 when the grain "heads out," to the period of bloom. 

 Kelatively considered, there occur great variations in the 

 same part of the plant at different stages of growth. 

 Thus, in the ear, which contains the least fiber, the 

 quantity of this substance regularly diminishes, not 

 absolutely, but only relatively, as the plant becomes 

 older, sinking from 37 per cent at heading to 13 per 

 cent at maturity. In the leaves, which, as regards 

 fiber, stand intermediate between the stem and ear, this 



* Arendt selected large and well-developed plants, divided them into 

 six parts, and analyzed each part separately. His divisions of the 

 plants were : 1, the three lowest joints of the stem ; 2, the two middle 

 loints ; 3, the upper joint ; 4, the three lowest leaves ; 5, the two upper 

 leaves; 6, the ear. The stems were cut just above the nodes, the leaves 

 included the sheaths, the ears were stripped from the stem. Arendt 

 rejected all plants which were not perfect when gathered. Wlien 

 nearly ripe, the cereals, as is well known, often lose one or more of 

 their lower leaves. For the numerous analyses on which these conclu- 

 sions are based we must refer to the original. 



tl. e., Orude cellulose; see p. 45. 



