24 BULLETIN 183, U. S. DEPARTMENT OF AGRICULTURE. 
Manchuria and Oderbrucker barleys, the nature of the secreting sur- 
face is of importance. 
As the size of the grain increases, the efficiency of the converting 
power becomes a vital question. The relative decrease of the sur- 
face of the epithelial layer, together with the increased percentage 
of starch in the endosperm, makes an adequate amount of diastase 
of the utmost importance, especially if it be desired to convert 
starch in addition to that already in the endosperm. ‘To have the 
largest contact area, the embryo must completely occupy the prox- 
imal end of the grain, and the grain itself must be as broadly oval 
as possible in order to provide for this maximum expansion. When 
these conditions are fulfilled, the resulting scutellum is a broad organ, 
reaching well over the shoulders of the grain and resting in a shallow, 
saucer-shaped depression in the endosperm. 
To test the accuracy of this conclusion, examinations have been 
made of almost every commercial barley in the world. Several of 
the types found are shown in Plate V, figure 2, and in Plates VI and 
VII. In all cases where the grains were large, the varieties recog- 
nized as superior malting barleys each possessed a scutellum of the 
above type. On the other hand, barleys known to be inferior for 
malting were invariably characterized by the other extreme of 
scutellum, that is, by one which did not reach out over the shoulder 
of the grain. Usually a slight compensation for defective breadth 
of scutellum was offered by its being deeply sunken in the endosperm. 
This addition of surface was shght, as it must be readily realized that 
the increase of the few degrees of surface secured could not offset the 
very considerable decrease of diameter. The comparative area of 
the spherical surface of the large scutellum is actually greater than 
that of the slightly elongated, small one, so that the broad, flat type 
of necessity presents the greater secreting surface. 
There seems to be a more or less definite correlation between the 
shape of the scutellum and the form of the grain. A long, pointed 
grain is almost invariably accompanied by a narrow, deeply sunken 
scutellum. Of course, the fact that the proximal end was reduced 
would of necessity cause a like reduction of the embryo. However, 
even more than such inevitable restriction usually occurs. In such 
grains the borders of the scutellum in a moistened grain do not ordi- 
narily protrude at the points of contact with the aleurone layer, but 
are even more narrow than the available space requires. In a very 
few types, as the Smyrna, this is not wholly true. 
While the most important factor of enzymatic production is thus 
seen to be the surface area of the secreting organ, there is still an 
additional element. There may be a difference in the quality of the 
secreting tissue. In other words, the epithelial layer varies with 
reference to the character of its cells. In some barleys it is made up 
of short, broad cells; in others the units are long and narrow. (See 
