EFFECTS OF SELECTION ON THE YIELD OF CORN. 6 
variation must be regarded as possibly influencing productiveness. 
Accordingly, a plat of each generation was grown at Burdette, Ark., 
in 1920, and between 50 and 60 hand-pollinated ears were obtained 
from each plat. The pollen for these ears was taken from a different 
plant or plants in the same plat as the pistillate parent. In this way 
each generation was advanced, F x producing F 2 , F 2 producing F 3 , etc. 
Similarly, plats of each parent variety were grown and hand -polli- 
nated ears representing Whatley X St. Charles White, its reciprocal 
cross, and each of the parent varieties were obtained. The seed of 
the parents planted in 1920 was obtained in 1916, the Whatley from 
the originator of that variety and the St. Charles White from L. H. 
Benne, on whose farm the original cross was made in 1914. The 
Whatley used in 1916 came from another source than that of 1914, 
but nothing has been found to suggest that this influenced the 
results. 
The 1920 plat planted with No. 201, F 6 , was on slightly lower 
ground and was completely drowned out following heavy rains in the 
spring. Consequently, no comparable F 7 seed was produced. The 
intention was to use the F 7 seed for planting the check plats. To 
take the place of this, the plants in the guard rows were hand-polli- 
nated inter se, and the resulting seed was designated Xo. 201, check. 
The constitution of Xo. 201, check, is of no interest here, as its pro- 
ductiveness is used only to compare the different generations with 
the crosses between inbred strains that are considered later. All the 
seed used in the 1921 comparisons except X T o. 201, F 1? therefore, was 
grown in the same season and under the same conditions. No. 201, 
F v was remnant seed of the 1914 crop and therefore 6 years old 
when planted. 
In order to avoid ambiguity, the seed classes considered and com- 
pared in these experiments are listed below, with their interrelation- 
ships indicated. 
The parent varieties: Whatlev and St. Charles White. 
Whatley X St. Charles White CB\) and St. Charles White X What- 
ley (Fj) : The reciprocal crosses between the varieties mentioned, the 
pistillate parent being named first. These crosses were made at 
Burdette in 1920 by hand pollinating. Whatlev X St. Charles 
White is the homologue of No. 201, F r 
U. S. Selection Xo. 201 is used to designate the original cross, 
Whatley x St. Charles White, made in 1914, and the succeeding 
filial generations of that cross. The individual generations will be 
indicated in the usual way, the first as No. 201, F t ; the second as 
No. 201, F 2 , etc. 
METHOD OF COMPARISON. 
The productiveness of the different classes of seed was compared 
at Burdette, Ark., in 1921. The soil was a better drained phase of 
Sharkey clay loam, with sand spots. Most of the sand blows were 
small, the largest not extending more than 30 feet in the longer 
direction. The alternation between these higher sand spots and lower 
areas of heavy clay was the principal cause of the irregularities in 
yields evidenced by the data. 
The plat was marked off both ways into rows 3% feet apart, and 
four seeds were planted in each intersection with a modified hand 
planter. The corn was planted on May 7. Showers on May 9 and 
