10 BULLETIN 1354, U. S. DEPARTMENT OF AGRICULTURE 
ticular relation is evident between the yields of the crosses and that 
of their parents; in fact, the coefficient of correlation between the 
yields of the crosses and those of the pistillate parent lines is —0.07 
±0.12. 
DETERMINING THE VALUE OF INDIVIDUAL LINES FOR CROSSING 
The primary object of the breeding experiments with No. 201 was 
to determine whether larger yields of corn could be obtained by the 
methods used. In a previous publication (6) it was stated that 
"the method of crossing [varieties] followed by mass selection has 
established a variety of economic value for the locality." That this 
variety continues to be of economic importance is shown by the fact 
that No. 201 has been accepted for certification under the name Delta 
Prolific by the Arkansas Seed Growers' Association, four growers, 
offering a total of 950 bushels of certified seed of this variety for 
Elanting in 1925 (1). The data presented here show comparisons 
etween the productiveness of check plants grown from open- 
fertilized seed of No. 201 (Delta Prolific) obtained from the Burdette 
Plantation and crosses between individual lines of this variety that 
had been self-fertilized for six generations. Any significant increases 
over the yield of the check, therefore, must be considered as evidence 
that the productiveness of a commercially profitable variety can be 
increased by the methods used. Whether such increases are worth 
while practically will depend upon a number of factors that are dis- 
cussed in connection with the data. 
OBTAINING THE CROSSED SEED 
In the experiments reported previously (6) comparisons were 
made between strain crosses. Each of the parent strains was repre- 
sented by a composite of a number of lines, some of which were very 
diverse in character. Strains Nos. 2-2-, 5-1-, 7-4-, and 10-3- had 
the highest average value as parents and gave the best average 
results when crossed among themselves. The present experiments 
were planned to measure the value for crossing of the individual 
lines in these strains. 
The selection of the individual lines for crossing was made among 
the rows of the breeding plat at Knoxville, Tenn., in 1922. An effort 
was made to include as much diversity as possible, considering both 
the pedigree records and the appearance of the plants. Thus, two 
lines of a strain that showed striking differences in plant character- 
istics might be included without regard to when they had segregated 
for these differences. Similarly, different lines of a strain might be 
included because they had become separated after only two genera- 
tions of inbreeding, whether they looked alike or not. Representative 
plants of a number of these inbred lines are shown in Plates II to 
VI. Representative plants of crosses between the lines and of open- 
fertilized noninbred No. 201 also are shown for comparison. All of 
the plants illustrated were grown at the Arlington Experiment Farm 
and were unselected, not more than 10 plants of any line or cross 
having been available. 
In all, 18 lines in the four strains were selected, and as many crosses 
between the individual lines of the different strains were made as 
conditions permitted. One additional line, 10-3-1-2-1-5, was used 
to supplement the sib line, 10-3-1-2-1-4. Besides this, tassels from 
