150 BOTANY OF CROP PLANTS 



ceed to the point when the young shoot (acrospire) breaks 

 out from under the lemma and palet, but the process is 

 checked by transferring the germinating grain to a kiln 

 where it is kept for about twelve hours at a temperature 

 sufficient to thoroughly dry it out. During germination, 

 there is secreted from the epithelial layer of the scutellum a 

 diastase which converts the starch to maltose sugar. Pep- 

 tase is also secreted by the germinating barley; this enzyme 

 modifies the albuminoids of the malt. 



Mashing. — The malt, prepared as above, is cleaned, and 

 crushed in a roller mill. It is then mixed with water, and 

 in some cases with unmalted cereals. The mash is then held 

 at the proper temperature for the action of diastase and pep- 

 tase, which chemically invert the starch into maltose, malto- 

 dextrin and dextrin, and change the insoluble albuminoids 

 to a soluble form. 



Boiling the Wort. — The product of the mashing machine is 

 called "wort." During the boiling process, hops are added. 

 Boiling serves not only to extract desirable products from 

 the hops, but to render harmless certain undesirable con- 

 stituents. After boiling, the wort is strained into coolers. 



Fermentation. — Yeast is now added to the wort. This 

 introduction of yeast is called "pitching." Through the 

 activity of yeast, the sugar in the wort is changed to alcohol 

 and carbon dioxide. The wort has been changed to beer. 

 It is removed from the fermenting vat, stored for a period to 

 allow certain products to settle, and also to permit of after- 

 fermentation, and then clarified, filtered, and packed for 

 the market. 



Production ,of Barley. — The four leading countries, in 

 1915, in the production of barley were: Russia, United 

 States, Germany, and Austria-Hungary, producing respec- 

 tively 475,109,000; 277,009,000; 150,000,000; and 136,186,000 

 bushels. 



