Corn Investigations 
65 
It is interesting to note that the principal character, viz, 
ratio of leaf area to dry matter, showed an identical difference 
for the two groups in all three conditions — before inbreeding, 
after inbreeding, and after crossing. The plant and ear types, 
which had been fairly well fixed by ordinary plant selection 
within a variety, were carried over thru the inbreeding period 
for five years and retained in the F 1 pure line hybrids. 
The F 1 hybrids between low leaf and high leaf area pure 
lines were intermediate in their ratio of leaf area to dry weight 
and also in ear type. Considerable variation occurred between 
different hybrids in yield of grain per acre, but as an average the 
hybrids were considerably more productive than the original. 
The yields of the low leaf hybrids, high leaf hybrids, low by high 
leaf hybrids, and the original averaged respectively 61.7, 55.6, 
59.2, and 55.1 bushels. This is a 12 per cent greater yield for 
the average of the low leaf pure line hybrids compared with the 
original variety, while the highest yielding individual hybrid 
yielded 34 per cent more. 
RELATION BETWEEN VIGOR OF PURE LINE PARENTS AND PRODUCTIVITY OF 
FIRST GENERATION HYBRIDS 
There has been much speculation regarding the relation be- 
tween the vigor of the pure lines and of their hybrid progeny. 
The general concensus of opinion among students of this prob- 
lem would seem to support the theory that those elemental 
strains which undergo the least reduction from inbreeding are 
likely to produce the most productive hybrid offspring when 
crossed. 
The observations at this Station bearing upon this point 
may be of interest, altho they are hardly of sufficient extent to 
warrant conclusions. The yields of eight F 1 hybrids and their 
inbred parents are given for 1916 in Table 22. The average 
yield of the four hybrids in each of which the lowest yielding 
parent yielded not to exceed 3.1 bushels per acre was 45.0 
bushels. In comparison, the average yield of the four hybrids 
in none of which the lowest yielding parent produced less than 
8.0 bushels was 58.5 bushels per acre. 
The average superiority in grain yield of the inbred parents 
of the second group over those of the first group was 34 per 
cent. In comparison, the average superiority in grain yield of 
the F, hybrids of the second group was 30 per cent over the 
hybrids of the first group. 
In Table 23 are compiled the average yield per acre during 
two years for eighteen F 1 low leaf area hybrids and the average 
