ON CORN BREEDING 137 



kernels. It is exactly the same principle which now prevails 

 in the work of the Swedish Agricultural Station at Svalof. 



The comparative trial of the progeny of the ears selected 

 in the field is made on a separate field plot, which is usually 

 called the breeding plot. Every corn grower should have 

 such a breeding plot. Here the grains of each ear are sown 

 in groups, so that it may be easy to compare the different 

 groups with one another. Two methods have been pro- 

 posed, the row system and the plat system. In the first, the 

 kernels of one ear are sown on a row by themselves, the 

 second row containing the progeny of a second ear and so 

 on. By this means the comparison of the rows is the basis 

 of judging the mother ears. Experience has shown that this 

 system is the most convenient, and it is now generally in 

 use. It is, however, exposed to the maximum degree of cross- 

 pollination and this must manifestly affect the purity of its 

 harvest. In the system of breeding in plats, the progeny of 

 each selected ear constitutes a square by itself, and thus at 

 least for the central stalks a high degree of pure fertilization 

 by the other members of the same family is insured. The 

 observed fact of the high degree of individuality of each 

 family, derived from one single ear, seems to point out the 

 desirability of this plat system for the first year of trial on 

 the breeding plot, even if the row system should be kept as 

 the most convenient for the subsequent years of selection. 

 The experience gained at Svalof would justify the expectation 

 of a considerable shortening of the number of years, re- 

 quired to reach the limit of possible purity, by the adoption 

 of the plat system for the first year of comparative trial. 



A breeding plot usually embraces about 100 rows, each 

 derived from one mother ear, and in each row about one 

 hundred hills, planted with three seeds each. At husking 

 time each row is harvested separately and the total weight 

 of its ears is the main factor of the comparison, since aug- 



