6 BULLETIN 189%, U. S. DEPARTMENT OF AGRICULTUR# 
the selfed block expressed as a percentage of the crossed blocks was. 
from 80.6 to 85.4 per cent. | 
These results indicate that in the crossed blocks there is as much 
genetic diversity in the plants of a row as among plants from differ- 
ent rows and taken at its face value would suggest the futility of 
ear-to-row breeding as compared with plant selection in a cross- 
pollinated stock. In the selfed blocks the progenies have become 
more nearly homozygous and the individual differences are largely 
environmental. 
In both the crossed and selfed blocks the high plant selections 
have been descriminated against in that the high row selections were 
oe first and the high plant selections were restricted to what was. 
eft. 
1923 1922 1921 1920 I9fg I9tg I9t” 
712 
FP 
FY, j F-2/) 
FFI/9 
SY 
Ax/O 
CaF 
FLY 
IS 
Bites 
428 
Fic. 1.—Representative pedigree of progenies in the crossbred seed stock of maize tested in 1923. Num- 
bers in the pedigree indicate individual plants. The numbers in 1917 are those assigned to the orig- 
inal ears first planted in 1918. F=11.2 
The pronounced superiority of the selections from high-yielding 
progenies compared with selections from high-yielding plants taken 
with the parent-offspring correlations in the selfed experiment 
demonstrates that substantial progress was made in the isolation 
of high-yielding lines in that experiment. 
YIELD COMPARISONS OF THE TWO BREEDING METHODS IN 1923 
After selecting the ears for continuing the experiments in 1923, the: 
remaining hand-pollinated ears from the 1922 crossed block were 
shelled into a mixed sample designated CB and the yield compared 
with that of a mixed sample of F, seed of hybrids between selfed lines, 
The selfed lines were crossed originally in 1921, and in 1922 crosses. 
were made among the several F, progenies. The mixture of these 
F, progenies was taken as representing tentatively the end result. 
of the selfed method. 
