PLANT BREEDING 



183 



Greatly increased care in its selection would probably at once 

 add more than $100,000,000 to the annual value of our corn 



^ crop. The structure 



^^ of the grain of corn, 

 as shown by the dia- 

 grams in figures 157 

 and 158, is such that 

 the relative amounts 

 of proteins, starch, and 

 oil can be roughly 

 estimated by a me- 

 chanical examination 



A B 



FIG. 157. Kernels of corn with high and with 



low percentage of proteins 



A, high proteins, B, low proteins ; p, horny layer, 

 consisting largely of proteins; s, white starchy 

 portion; e, embryo. After Bulletin 87, Univer- 

 sity of Illinois Agricultural Experiment Station 



of the grain. This most important fact was discovered by 

 Professor C. G. Hopkins, of the University of Illinois. The 

 proteins are very largely stored in the horn-like part of the 

 endosperm (fig. 157, 

 JP), and in the embryo; 

 the starch is mainly 

 found in the white, 

 floury part of the en- 

 dosperm (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 devel- 

 oped, the result will 

 be 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. 



FIG. 158. Kernels of corn with high and with 

 low percentage of oil 



A,A-i, cross section and face view of high-oil 

 kernels; B,Bi, cross section and face view of 

 low-oil kernels ; e, embryo. Most of the oil (as well 

 as a good deal of the proteins) is contained in the 

 embryo, so that an embryo large in proportion to 

 the size of the kernel means a high percentage 

 of oil in the grain. After Bulletin 87, Univer- 

 sity of Illinois Agricultural Experiment Station 



