420 



PRACTICAL BOTANY 



more than $100,000,000 to the annual value of our com crop. 

 The structure of the grain of corn, as shown by the diagrams 

 in Figs. 333 and 334, is such that the relative amounts of pro- 

 teins, starch, and 

 oil can be esti- 

 mated roughly 

 by a mechanical 

 examination of 

 the grain. This 

 most important 

 fact was discov- 

 ered by Professor 

 C. G. Hopkms, of the 

 University of Illinois. 

 The proteins are largely 

 stored in the horn-like part of 

 the endosperm (Fig. 333, p) and 

 in the embryo ; the starch is mainly 

 found in the white, floury part of the 

 endosperm (s) ; and the oil is nearly all in 

 the embryo (e). If seed corn is chosen from 

 ears with kernels in which the horn-like 

 portion is highly developed, the result will 

 be to secure a crop with a large percentage 

 of proteins ; seed corn with large embryos 

 will yield a crop rich in oil, and seed corn 

 with small embryos a crop poor in oil. 



Corn with high proteins is especially 

 valuable as a food for man and the lower 

 animals, since the most serious fault found 

 with corn as a cereal food is its low per- 

 centage of proteins compared with its oil 

 and carbohydrates. Corn with high oil value is especially de- 

 sired by the glucose manufacturers, since they also manu- 

 facture corn oil, which is the highest-priced component of the 

 grain. Corn with a low percentage of oil is in demand for 



Fig. 335. Part of a 

 corn tassel (stami- 

 nate flower cluster) 



6r,abract; 5<,stamens. 

 One half natural size 



