32 BULLETIN 183, U. S. DEPARTMENT OF AGEICULTUEE. 



The efficiency of conversion depends upon the shape and compo- 

 sition of the grain and upon the relative quantity of diastase secreted. 

 The quantity of diastase in turn is dependent upon the size, vigor, 

 and condition of the epithehal layer. The greatest secreting area for 

 a o-iven orain is secured with a scutellum extending well over the 

 edges of the adjacent endosperm, the greatest vigor in an epithehal 

 layer of long, narrow cells, the highest condition of efficiency in a 

 weU-matured, well-cured grain. 



The ideal grain of barley is one that is broadly oval with a scutellum 

 of the type described. If a large yield of malt extract is desired, the 

 size of the grain should be large ; if diastase be the main consideration, 

 the size should be smaller. 



Barley grains with pointed ends and a narrow scutellum are to be 

 avoided. Poorly matured grain should also be avoided. 



The highest type of the barley grain is secured only w^hen chmate, 

 culture, and variety are all favorable. 



Pedigreed varieties are essential for securing barleys of superior 

 morphological and physiological quahty. Such varieties must for the 

 most part be produced in this country, as imported pedigreed stocks 

 are seldom satisfactory. 



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