32 BULLETIN 183, U. S. DEPARTMENT OF AGRICULTURE. 
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 epithelial layer. The greatest secreting area for 
a given gram is secured with a scutellum extending well over the 
edges of the adjacent endosperm, the greatest vigor in an epithelial 
layer of long, narrow cells, the highest condition of efficiency in a 
well-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 when climate, 
culture, and variety are all favorable. 
Pedigreed varieties are essential for securing barleys of superior 
morphological and physiological quality. Such varieties must for the 
most part be produced in this country, as imported pedigreed stocks 
are seldom satisfactory. 
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WASHINGTON : GOVERNMENT PRINTING OFFICE : 1915 
