157 



whose grains show a relatively small proportion of the white, starchy 

 part surrounding the germ. 



All the grains of corn in any one ear are almost identical in their 

 chemical composition, so that the whole ear may be judged by one grain. 



There is a wide variation in the chemical composition of different 

 ears even in the same patch of corn, so that it is quite possible to alter 

 the character of the crop year by year, by selecting on simple inspec- 

 tion so as to increase, as may be desired, either the starch or the protein. 



For a satisfactory breerting plot, about 20 to 40 selected seed ears 

 are required. If the breeder desires to make only physical improve- 

 ment then he should select, say 40 of the most nearly perfect ears 

 which it is possible to pick out. If it is desired to improve the com- 

 position or quality of the corn as well as the physical properties, then 

 at least 200 perf^ ct ears should be selected, and from these 200 ears 

 the 40 ears wh^ch are most suitable as seed for the particular kind of 

 corn which it is desired to breed should be selected. 



The 40 selected seed ears are planted in 40 separate parallel rows, 

 one ear to a row, consequently the breeding plot should be at least 40 

 corn rows wide and long enough to require about three-fourths of an 

 ear to plant a row. It is well to shell the remainder of the corn from 

 all of the 40 ears, mix it together, and use it to plant a border several 

 rows wide entirely around the breeding plot, to protect it, especially 

 from foreign pollen. 



The very best ears of seed corn are planted in the centre rows of the 

 "breeding plot, the remainder of the ears being planted in approxi- 

 mately uniform gradation to either side, so that the least, desirable 

 ears among the 40 are planted in the outside rows ; and in the final 

 selection of the best field rows from which the next year's seed ears 

 are to be taken, some preference is given to the rows near the centre 

 of the plot. 



Dr. Hopkins recommends that every alternate row of corn in the 

 breeding plot be completely detasseled before the pollen matures and 

 that all the seed corn to be taken from the plot be selected from these 

 20 detasseled rows. This method absolutely prohibits self-pollination 

 or close-pollination of the future seed. By self-pollination is meant 

 the transfer of pollen from the male flower of a given plant to the fe- 

 male flower of the same plant ; and by close pollination is meant the 

 transfer of pollen from the male flower of one plant to the female 

 flower of another plant in the same row, both of which grew from 

 kernels from the same seed ear. 



The transfer of pollen from one plant to another plant which grew 

 from kernels from a different seed ear, is termed cross pollination. 



It is also recomended that in the 20 rows of corn which are not de- 

 tasseled, no plant which appear imperfect, dwarfed, immature, barren, 

 or otherwise undesirable, should be allowed to mature pollen. Detas- 

 seling is accomplished by going over the rows two or three times and 

 carefully pulling out the tassels as they appear. 



Occasionally an entire row is detasseled because of the general in- 

 leriority of the row as a whole. 



As the corn approaches maturity it is time to begin at the real be- 

 ginning in the selection of seed corn; that is with the whole corn, 

 crop and the whole corn plant, as it stands in the field. 



