2 BULLETIN 1209, U. S. DEPARTMENT OF AGRICULTURE. 
than the cross. The pistillate parent, Whatley, was not included 
in this experiment because of its late maturity. 
St. Gharles White is recommended highly by the Missouri Agricul- 
tural Experiment Station for the lowlands of southeastern Missouri, 
where tlie environment is entirely similar to that at Armorel. In 
addition to its significantly high yield, the cross had well-proportioned 
plants, was of the proper maturity, and produced a high percentage 
of sound grain. In view of this all-round desirability it was decided 
to propagate it further. Some 20 or more F 1 plants^had been grown 
in 1915 in a garden at St. Charles, Mo., where they were isolated 
from other corn, and about 40 ears of F, seed were available from this 
plat. These were planted in a 2-acre field at Armorel in 1916 under 
the designation IT. S. Selection No. 201. Open-fertilized mass 
selection and selection within self-fertilized lines were begun with 
this crop and have been continued since that time. The present 
bulletin reports the comparative yields of different generations under 
mass selection and of crosses between lines that had been self -fertilized 
for four generations prior to crossing. 
RESULTS OF MASS SELECTION. 
METHOD OF SELECTION. 
The fundamental basis of selection was the production of sound 
grain per plant. Such factors as time of maturity, height of plant, 
and position and size of ear also were considered. It seemed that this 
would provide a standard for measuring the results of selection 
within self-fertilized lines and at the same time provide possibly 
a variety of economic value for the locality in which the experiments 
were being conducted. 
Whatley commonly bears two or more small ears per plant. St. 
Charles White, the other parent, is a single-eared variety; under 
favorable conditions many plants will bear two ears, but three-eared 
stalks of St. Charles White are rare. The high yield of the F t genera- 
tion of the cross between these varieties was due to the fact that 
practically every plant produced two fair-sized ears. Other data 
and observations also indicated that the two-eared condition was 
desirable. Accordingly, selection at first was largely from two- 
eared stalks. By 1918, however, there was too large a proportion 
of plants bearing three or more small ears that increased the labor 
of handling without apparently producing a compensating increase 
in yield. Beginning with this crop, therefore, more attention was 
paid to size and less attention to number of ears. What effect, if any, 
this has had on size and number of ears is shown in Table 2, which 
gives these data both for the different generations and for the parent 
varieties. 
The successive crops up to and including that of 1918 were grown 
at Armorel, Ark. Since that time they have been grown at Burdette, 
Ark., about 15 miles from Armorel. From 5 to 50 bushels of seed 
were selected each year, and the area planted varied from 20 to 80 
acres. 
GROWING SEED FOR COMPARISON. 
A sample of each year's seed was retained in the corn laboratory 
at Washington, D. C. In the absence of definite evidence, differences 
in the age of seed as well as differences in development due to seasonal 
