Journal of Agricultural Research voi.xvin, no. i 



hitherto pointed out concerning the physiology of this plant and the 

 relations between the various parts of the plant as maturity is approached. 

 It is well to keep in mind, while perusing the graphs and data, that the 

 sorghum plant, so far as we are concerned in the present investigations, 

 is cultivated primarily for its sugar content. The data repeatedly 

 reveal the subservience of all other constituents to the sugars. This 

 same phenomenon has been pointed out for many other plants which 

 specialize in the production of some one class of substances, as the starch 

 in potato tubers and in corn seed, the sugars in fruits, the oil in flax, 

 peanuts, and soybeans, and the sucrose in sugar beets and in sugar cane. 



mum 



Fig. I. — Development of the proximate and mineral constituents of the sorghum plant in the later 



stages of growth. 



The results of the analytical studies are presented only in graphs, 

 since their presentation in tables adds nothing to what is given in the 

 charts. 



Figure i shows the composition of the whole plant, expressed as per- 

 centages of the green plant and of the dry matter. The ash constituents 

 are expressed as percentages of the total ash. The nitrogen content is 

 computed to the ash basis, so as to make it comparable to the phos- 

 phorus and potash. There is a gradual increase in dry matter from 

 about 12 per cent to about 26 per cent. Of this dry matter, the most 

 prominent constituents are the fiber and the nitrogen-free extract. The 

 latter is mostly starch, dextrose, and levulose in the younger stages, and 

 mostly sucrose in the older. The percentages of fiber and of the other 

 carbohydrates undergo progressive changes which are almost exactly 

 equal to each other but opposite in character — that is, the percentage of 



