Corn Investigations 
79 
This is strikingly different from the results with pure line 
hybrids, where greatly reduced yields resulted from planting 
second or third generation seed, (see chart 2). This difference 
in behavior between pure line hybrids and variety hybrids in 
Table 30. — C omparison of first , second , and third generation 
variety hybrids with the parent averages. 1915-1917. 
Yield per acre 
Description 
3-year average, 1 
915-1917 
2-year averaj 
re, 1916- 
1917 
Fi 
F 2 
Both 
parents 
Fi 
f 2 
f 3 
Both 
parents 
Bu. 
Bu. 
Bu. 
Bu. 
Bu. 
Bu. 
Bu. 
(1) 
(2) 
(3) 
(4) 
(5) 
(6) 
(7) 
(8) 
Reid’s X Hogue’s 
39.7 
40.1 
42.0 
36.0 
37.1 
35.5 
39.3 
Iowa Gold Mine X Hogue’s 
39.4 
35.9 
39.4 
34.5 
34.3 
35.6 
36.2 
Learning X Hogue’s 
Calico X Hogue’s 
39.7 
43.3 
40.1 
35.1 
40.3 
39.3 
37.5 
36.8 
40.0 
40.4 
35.9 
39.4 
36.6 
38.5 
Bloody Butcher X Hogue’s ....... 
U. S. S. Brush X Hogue’s 
33.9 
35.9 
39.8 
35.3 
33.5 
30.3 
38.3 
35.7 
38.7 
36.8 
35.7 
38.3 
37.6 
38.1 
St. Charles White X Hogue’s 
Iowa Silver Mine X Hogue’s 
39.0 
40.7 
39.7 
36.9 
37.3 
36.9 
38.2 
38.7 
40.3 
40.0 
34.3 
39.7 
36.9 
38.9 
Nebraska White Prize X Hogue’s . . 
37.4 
37.3 
39.0 
37.1 
35.4 
39.7 
39.1 
Pride of the North X Hogue’s 
37.7 
38.6 
39.6 
34.1 
38.9 
38.3 
36.8 
Minnesota No. 13 X Hogue’s 
White Cap X Hogue’s 
39.0 
36.2 
36.7 
32.6 
31.3 
28.7 
32.3 
37.2 
40.7 
37.6 
35.7 
36.7 
34.7 
35.3 
University No. 3 X Hogue’s 
39.6 
40.0 
39.9 
36.4 
37.3 
30.3 
38.2 
General average 
38.0 
39.1 
39.3 
35.3 
36.8 
35.4 
37.4 
these later generations may be accounted for by the difference 
in the number of elemental strains represented in their basic 
composition. There is a cardinal difference between the be- 
havior of second and later generations of pure line hybrids and 
that of variety hybrids. In these experiments the F 2 and F 3 
variety hybrids and pure line hybrids were produced by close 
breeding a number of ears in the F t and F 2 generations re- 
spectively, with composite pollen from a number of plants. In 
regard to Mendelian factors, this corresponded to broad fertili- 
zation in the case of the former, and self-fertilization in the lat- 
ter. The second generation seed was equivalent to composite 
seed as picked by a farmer from promiscuously pollinated fields 
of corn planted to first generation hybrids. Second and later 
generations lack the plant uniformity possessed by the first 
generation. 
