2Q2 AGRICULTURAL CHEMISTRY 



illustration (Fig. 90) here shown was made from a photo- 

 graph taken of the corn kernels and sections with a mag- 

 nification of three diameters. At the left are two sections 

 and a whole kernel from corn containing 14.92 per cent, of 

 protein. The sections and kernel at the right are from corn 

 containing 7.76 per cent, of protein. About one-fourth 

 of the kernel was cut off from the tip end in making the 

 cross sections. In the longitudinal sections the tip end 

 of the kernel points upward to the right. It will be 

 seen that in the cross sections the white starchy layer 

 nearly disappears in the high -protein corn, but becomes 

 very prominent in the low-protein corn. In the longi- 

 tudinal sections this difference is also apparent, the white 

 starch in the high-protein corn being confined almost en- 

 tirely to the crown end of the kernel, while in the low- 

 protein corn it extends into the tip end in considerable 

 amount. The germ in the high- protein corn is somewhat 

 larger. This is also indicated by the depressions in the 

 whole kernels." 



Exceptions are, however, occasionally observed in the 

 relation of the form to the protein content of corn, but 

 in making comparisons in the manner indicated, the few 

 errors which are liable to occur are in assigning too low 

 rather than too high a protein value to the sample. In 

 the selection of seed corn a knowledge of the character- 

 istic of the kernels as nitrogenous or non-nitrogenous will 

 be found of value. 



Experiment 72. Select, from a sample of corn, kernels of high- 

 and kernels of low-protein content. Make longitudinal and cross 

 sections of some of the kernels, and note the proportion of germ, 



