No. 7. DEPARTMENT OF AGRICULTURE. 486 



of animals has che advantage of the breeder of plants in that he can 

 more easily control the mating of parents. The breeder of plants 

 has a distinct advantage in being able to work with large numbers. 



In the case of live stock, only the inferior females can be discarded, 

 because in working with adults the expense of discarding the adults 

 cannot be afforded. Indeed the number of sires that are to be found 

 in the upper end of the curve is so small that the sires are apt to be 

 but little if any better than the average. In the breeding of animals, 

 in practice, it is the few inferior animals represented by the lower 

 end of the curve that are discarded. In the case of plants, however, 

 embryo plants (seeds) are produced in such abundance and at so 

 small expense that only the few at the upper end of the curve, which 

 are distinctly superior, need be saved. Instead of discarding the 

 poorest ten per cent, as in the case of animals, only the best five, or 

 even one per cent, may be saved in the case of plants. 



Improvement of Indian Corn : A grain of corn, like the grain of 

 wheat, is more than a seed. It is a fruit. It is a fruit in which the 

 pod is thin and dry and remains closely adnate to the seed which is 

 within. 



The pod consists of three coats, within which are two coats, the 

 so-called integment or testa. These five coats we may call the hull. 

 Inside the hull is a layer of large cubical cells. This layer is called 

 the aleurone layer. Inside is the endosperm. At the base of the 

 grain and on the side next the tip of the ear is the embryo or germ. 

 In cross section the two most conspicuous portions are the endos- 

 perm and germ. An examination of cross sections will show that 

 the germ may vary largely in size and that the endosperm varies in 

 appearance from snow-white to a translucent or icy appearance. 

 The relative proportion of white and translucent endosperm varies 

 greatly in soft, dent, flint and pop corn, while in sweet corn it has 

 been completely transformed. Most of the fat of a grain of corn is 

 to be found in the germ. It is obvious, therefore, that the grains 

 containing large germs will contain a large percentage of oil. 



Dr. Hopkins established that a row of kernels would chemically 

 represent the ear. He also established the fact that any man with a 

 pocket-knife could select corn for high oil or low oil content. He 

 further established that having selected ears containing high oil and 

 low oil content, they would transmit these characters. Beginning 

 with the same variety of corn, ears were selected for four years for 

 high and for low oil contents. Then ten rows of corn were planted 

 with both kinds of corn, every hill having each kind of corn just far 

 enough apart to identify the stalks. Thus they were grown in the 

 same season, in the same soil and under the same cultivation. The 

 corn selected for low oil contained 3.8 per cent, of oil; that for high 

 oil, 5.8 per cent, of oil. In other instances variations in content of 

 oil have been brought about ranging from 2.5 to 7.0 per cent. 



Dr. Hopkins has shown that the per cent, of protein in the horny 

 starch of an average ear of corn is 10.2 per cent, while in the white 

 starch it was less than 8 per cent. He has also shown that more 

 than 42 per cent, of all the protein of a kernel is in the horny starch. 

 Consequently he proposed that by selecting ears containing large 

 amounts of horny starch, any farmer with a jack-knife could breed 

 corn for high protein content. By this method, corn has been bred 



