210 HOW CEOPS GEOW. 



The following statement exhibits the Average Daily In- 

 crease of Carbon, Hydrogen, Oxygen, Nitrogen, and Ash, 



(in lbs. per acre) during the several periods. 

 Table X.— Br. 



Turning now to Arendt's results, which are carried more 

 into detail than those of Bretschneider, we will notice 



A. — Tlie Relative {percentage) Composition of tlie 

 Entire Plant and of its Parts * during the several periods 

 of vegetation. 



1 , Fiber \ is found in greatest relative quantity — 40° |„ — 

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

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

 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 2'7°]„, 

 at heading, to 12° |„, at maturity. In the leaves, which, as 

 regards fiber, stand intermediate between the stem and 

 ear, this substance ranges from 22° |^, to 38" |^. Previous 

 to blossom, the upper leaves, afterwards the lower leaves, 

 are the richest in liber. In the lower leaves the maximum, 



* 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 joints ; 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 cars were stripped from 

 the stem. Arendt rejected all plants which were not perfect when gathered. 

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

 lower leaves. For the numerous analyses ou which these conclusions are based 

 we must refer to the original. 



t 1. e,, Crude cellulose; see p. 60. 



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