94 Missouri agricultural report. 



ii the method of mechanical examination alone is employed in mak- 

 ing the chemical selection, then, if possible, there should be some chem- 

 ical control of the work, at least until the breeder has become sufficiently 

 skilled, or has had sufficient experience, to feel that he knows how to 

 make a chemical selection of seed ears by mechanical examination of 

 kernels. Such a chemical control does not involve a large amount of 

 chemical work. In Illinois the Experiment Station offers such a chem- 

 ical control to farmers who will agree to make the selection of the best 

 possible seed, both by physical inspection of ears and mechanical exam- 

 ination of kernels and who will further agree to secure data and breed 

 the corn in accordance with our directions. 



This control is aft'ected by analyzing only two samples of corn each 

 year; one composite sample of the rejected ears, five average kernels 

 being taken from each ear, and one composite sample of the 20 to 40 

 selected seed ears, twenty average kernels being taken from each of 

 these ears, and each of these two composite samples being properly 

 labeled and analvzed. 



One of the best selections which has yet been made by mechanical 

 examination was accomplished last spring by a farmer who is breeding 

 corn for higher protein content. Out of a lot of 165 ears of corn he 

 selected 15 ears whose protein content averaged 1.48 per cent higher 

 than that of the 150 rejected ears, as was determined by the chemical 

 analysis of a composite sample from each of the two lots. Because of 

 the chemical control which the station affords him, he knows each year 

 just how much he has accomplished. 



If the purpose of breeding a kind of corn is principally to change 

 its content of a single constituent, as to increase protein, then the selec- 

 tion of the best 40 ears is simple and regular by either method; but if 

 it is desired to effect changes in the content of two constituents, as to 

 increase the protein and to increase the oil in the same corn, then one 

 could hardly expect to make much progress in both directions, if he 

 relied solely upon mechanical examination of kernels for chemical selec- 

 tion of seed ears. Even after the chemical analyses of 100 ears have 

 been made it requires some computation to determine which are really 

 the best 40 ears. For example, an ear may be desirable for seed because 

 of its high protein content, but it may not be sufficiently high in oil. 

 In order to reduce the selection to an exact basis, we have adopted simple 

 mathematical computations for all such cases. 



For high protein and high oil in the same corn, we multiply the 

 percentage of protein by the percentage of oil and use the product as 

 the selection coeft'icient, the forty highest products designating the forty 

 best cars. 



