8 
BULLETIN 1354, U. S. DEPARTMENT OF AGRICULTURE 
4.1 bushels. In so far as the lines compared represent the breeding 
stocks as a whole, therefore, these averages indicate that selection 
has been effective in maintaining productiveness somewhat above 
what would be expected under self-fertilization without selection. 
Average B of Table 3 differs from average A in that only those 
lines represented directly in all generations are included. In some 
ways this would seem the fairer method of comparison, but the small 
numbers available may make the general average the more reliable 
approximation. In any event the difference is unimportant. 
YIELDS OF CROSSES BETWEEN LINES 
The yields of the crosses between lines after successive generations 
of self-fertilization are brought together in Table 4. The evidence 
here is not so clear as to individuality as it is for the behavior of the 
self -fertilized lines themselves. The averages shown as A and B are 
based upon all the crosses in a generation and upon those crosses in 
each generation that are represented by analogous crosses in all of 
the generations, respectively. No particular advantage is evident 
from inbreeding more than three generations before crossing in so far 
as average yield is concerned. 
Table 4. — Yields of crosses between lines of corn that had been self-fertilized for 
different numbers of generations 
Selfed 2 generations 
Selfed 3 generations 
Selfed 4 generations 
Selfed 5 generations 
Pedigree No. 
Yield 
per 
acre 
(bush- 
els) 
Pedigree No. 
Yield 
per 
acre 
(bush- 
els) 
Pedigree No. 
Yield 
per 
acre 
(bush- 
els) 
Pedigree No. 
Yield 
per 
acre 
(bush- 
els) 
2-2X7-1 
34.3 
(2-2-2 X 7-1-1. . 
12-2-1 X 7-1-1 . - 
42.6 
♦40.0 
/2-2-2-4X 7-1-1-1.. 
\2-2-2-4X7-l-l-2.. 
38.0 
37.1 
2-2-2-4-4X7-1-1-1-3.. 
2-2-2-4-4X7-1-1-2-3.. 
40.9 
33.9 
34.3 
41.3 
37.6 
37.4 
3-1-1X5-1-2.. 
/3-1-1-3X 5-1-2-5. . 
13-1-1-4X5-1-2-3- 
3-1-1-3-1 X 5-1-2-5-2. . 
3-1-1-4-3 X 5-1-2-3-1 .. 
3-1X5-1 
26.3 
43.3 
43.3 
46.9 
37.4 
40.1 
31. 6 
26.3 
42.2 
35.9 
(9-2-1X12-1-2. 
^9-2-2X12-1-1. 
9-2-1-2X12-1-2-3. 
9-2-2-1X12-1-1-2. 
9-2-1-2-1 X 12-1-2-3-2. 
9-2X12-1 
43.3 
36.8 
*38. 1 
43.8 
*28.6 
41.4 
9-2-3-2-3 X 12-1-2-3-2. 
*22.0 
43.3 
37.5 
36.2 
31.7 
TVTp 
f 12-1-1X2-2-2. 
j 12-1-1X2-2-1. 
[12-1-1-1X2-2-2-4. 
^12-1-1-1X2-2-2-2. 
1 12-1-1-2X2-2-2-4. 
12-1-1-1-2 X 2-2-2-4-4. 
12-1-1-1-2 X 2-2-2-2-3 . 
33.7 
33.1 
*34.8 
36.0 
37.9 
*37.5 
48.5 
37.9 
12-1X2-2 
f 12-1-2-3-2 X 2-2-2-4-4 . 
1 12-1-2-3-2 X 2-2-2-2-3 . 
*40.4 
*36. 2 
33.7 
34.0 
37.1 
40.8 
34.4 
34.4 
31.4 
31.4 
39.0 
39.0 
39.7 
39.7 
38.3 
40.2 
40.3 
37.5 
36.5 
39.5 
43.2 
34.5 
1 Average of means, including all crosses. 
2 Average of means, excluding crosses (marked *) not represented by analogous crosses in all generations. 
3 Average yileds of the better of each of 3 pairs of crosses made following 5 generations of self-fertilization 
that were represented by analogous crosses made after 4 generations of self-fertilization and of the corre- 
sponding antecedent crosses. 
4 Average yields of the poorer of each of 3 pairs of crosses made following 5 generations of self-fertilization 
that were represented by analogous crosses made after 4 generations of self-fertilization ana of the corre- 
sponding antecedent crosses, comparable to average C. 
