266 DRY-FARMING 
non-nitrogenous substances, including fats, woody 
fiber, and nitrogen-free extract, a name given to the 
group of sugars, starches, and related substances. 
These substances are used by the body in the pro- 
duction of fat, and are also burned for the production 
Fig. 63. Dry-farm Milo maize. Rosebud Co., Montana. 
of heat. Of these valuable food constituents protein 
is probably the most important, first, because it 
forms the most important tissues of the body and, 
secondly, because it is less abundant than the fats, 
starches, and sugars. Indeed, plants rich in protein 
nearly always command the highest prices. 
The composition of any class of plants varies con- 
siderably in different localities and in different sea- 
