COMPOSITION IN SUCCESSIVE STAGES. 223 



isons between the absolute quantities of its ingredients at 

 different stages of growth. We have obtained a series of 

 isolated views of the chemistry of the entire plant, or of 

 its parts at some certain period of its life, or when placed 

 under certain conditions, and have thus sought to ascer- 

 tain the peculiarities of these periods, and to estimate the 

 influence of these conditions. It now remains to attempt 

 in some degree the combination of these sketches into a 

 panoramic picture to give an idea of the composition 

 of the plant at the successive steps of its development. 

 We shall thus gain some insight into the rate and manner 

 of its growth, and acquire data that have an important 

 bearing on the requisites for its perfect nutrition. For 

 this purpose we need to study not only the relative 

 (percentage) composition of the plant and of its parts at 

 various stages of its existence, but we must also inform 

 ourselves as to the total quantities of each ingredient at 

 these periods. 



We shall select from the data at hand those which 

 illustrate the composition of the oat-plant. Not only the 

 ash-ingredients, but also the organic constituents, will be 

 noticed so far as our information and space permit. 



The Composition and Growth of the Oat-Plant 

 may be studied as a type of an important class of agricul- 

 tural plants, viz. : the annual cereals plants which com- 

 plete their existence in one summer, and which yield a 

 large quantity of nutritious seeds the most valuable re- 

 sult of culture. The oat-plant was first studied in its 

 various parts and at different times of development by 

 Prof. John Pitkin Norton, of Yale College. His labori- 

 ous research published in 1846 ( Trans. Highland and Ag. 

 Soc., 1845-7, also Am. Jour. ofSci. and Arts,Vol. 3, 1847) 

 was the first step in advance of the single and disconnected 

 analyses which had previously been the only data of the 

 agricultural physiologist. For several reasons, however, 

 the work of Norton was imperfect. The analytic meth- 



