116 CROPS 



solution to make it immediately available. By the time 

 the seedling rises into the light where it can begin the 

 manufacture of food, the roots have begun to absorb from 

 the soil necessary quantities of inorganic elements for the 

 synthetic processes. Straw and stover, on the other hand, 

 are high in ash which consists largely of the unessential 

 element silicon together with lime and potash. The stems 

 and leaves, it will be remembered (Section 48), are the seat 

 of synthetic processes requiring the help of mineral elements. 



Compared to other crops, seeds are high in crude protein, 

 crude fat and nitrogen-free extract, or carbohydrates, as 

 would be expected, since these are the stored foods for the 

 next generation. The carbohydrates are chiefly starch. 

 Straw and stover, on the other hand, are very high in crude 

 fiber, which goes to make cell walls and strengthening fibers, 

 not living matter. 



(a) Grains. — Considering the grains separately, it is to 

 be noted that barley seed is of importance chiefly for its 

 nitrogen-free extract — starch — and the very active starch 

 splitting enzyme, diastase, which is produced on germination. 

 These are made use of in the malting of barley and the sub- 

 sequent "mashing." Barley grains are soaked in water 

 and allowed to germinate. This results in the evolution of 

 heat (Section 3) and the production of diastase in large 

 quantities. All seeds during germination produce diastase 

 of some kind to dissolve the starch (Section 7), but barley 

 diastase is particularly active. When the sprouts have well 

 started they are killed by heat and removed, appearing on 

 the market as "malt sprouts," a feeding stuff. The barley 

 grains, now called malt, are still very rich in starch but have 

 in addition quantities of diastase The malt is next heated 

 with water when the diastase converts the starch to maltose, 

 a process called mashing. Diastase can act on the starch 

 of other grains as well as on that of barley, and in brewing 

 it is used for the hydrolysis of large amounts of corn starch. 

 The maltose is removed in solution, and fermented with 

 yeast, producing beer. The grain that is left behind is sold 

 as "brewers' grains" for feeding purposes. The presence of 

 much protein in the seed interferes with the malting process. 



