226 ILLINOIS DAIRYMEN'S ASSOCIATION. 



position. A side from the hull which surrounds the kernel, there are three 

 principal parts in a grain of corn: 



1. The darker colored and rather hard and horny layer lying next to 

 the hull, principally in the edges and toward the tip end of the kernel 

 where it is about 3 millimeters, or y 8 of an inch, in thickness. 



2. The white, starchy-appearing part occupying the crown end of the 

 kernel and usually also immediately surrounding, or partially surrounding, 

 the germ. 



3 The germ itself which occupies the central part of the kernel 

 toward the tip end. 



These different parts of the corn kernel can be readily recognized by 

 merely dissecting a single kernel with a pocket knife, and it may be added 

 that this is the only instrument needed by anybody in making a chemical 

 selection of seed corn by mechanical examination. 



The horny layer which usually constitutes about 65 per cent of the 

 corn kernel contains a large proportion of the total protein in the kernel. 



The white, starchy part constitutes about 20 per cent of the whoie 

 kernel, and contains a small proportion of the total protein. The germ 

 constitutes only about 10 per cent of the corn kernel, but, while it is rish 

 in protein, it- also contains more than 85 per cent of the total oil content 

 of the whole kernel, the remainder of the oil being distributed in all of the 

 other parts. 



By keeping in mind that the horny layer is large in proportion and 

 also quite rich in protein and that the germ, although rather small in pro- 

 portion is very rich in protein, so that these two parts contain a very large 

 proportion of the total protein in the corn kernel, it will be readily seen 

 that by selecting ears whose kernels contain more than the average pro- 

 portion of germ and horny layer we are really selecting ears which are 

 above the average in their protein content. As a matter of fact, the 

 method is even more simple than this, because the white starchy part is 

 approximately the complement of, and varies inversely as, the sum of tfce 

 other constituents; and to pick out seed corn of high protein content it 

 is only necessary to select those ears whose kernels show a relatively 

 small proportion of the white, starchy part surrounding the germ. 



