Oct. 22, 1917 Indirect Effects of Selections in Breeding Indian Corn 115 
marked seasonal fluctuations in the mean length of ears for each of 
these strains, there is no marked regular change in the length of the ear 
for any strain. From the graphs in figure 1 there is, however, at least 
some evidence that, on the whole, the mean length of ears has been 
smaller during the second half of the period 1905-1915, than during the 
first half of the period. But it seems in explanation of this, that in the 
second half of the period there were at least three years in which the 
length of ears showed decidedly the effects of abnormal seasons. 
There has been one progressive change worth noting, in that the mean 
lengths of ears for the high-protein strain for the past four years main¬ 
tained a position above the low-oil strain. The differences between the 
mean lengths of ears in the latter half of the period 1905-1915 are 
slightly larger, but hardly significantly larger than those that existed 
in the earlier part of the period. 
Since the probability that a given order of four elements in a trial 
under pure chance is 1 to 24, we note that there is a decided tendency 
to maintain order in mean length of ears, although there are a few 
exceptions. 
MEAN CIRCUMFERENCE OF EARS 
In the first year (1905) we find significant differences in the means 
except possibly for the case of the low-protein and the low-oil strains. 
For this pair we find a difference of 0.14±0.03. While, under random 
sampling, we should probably ascribe at least some slight significance 
to such a difference, it is doubtful whether the difference is large enough 
to persist regularly under differences of seasons and soil. But, based 
on 11 years' experience, we find that the low-protein strain has always 
shown a smaller mean circumference than the low-oil strain, except in 
the one year (1908) when the two were substantially equal. 
We note from figure 2 the regularity with which the order of 1905 
has been maintained. The order for circumference of ears has been at 
least as well maintained as that for the length of ears, and perhaps a 
little more persistently. Figure 2 shows that the mean circumference 
of the high-oil strain was lower than that of the high-protein strain in 
the year 1913 only. 
As to progressive changes, it is true, on the whole, that each of these 
strains shows a smaller mean circumference in the second half of the 
period 1905-1915 than in the first half, but it is not unlikely that this is 
due to seasonal fluctuations. What is more important for our purposes 
is to note that the mean differences between mean values are no more pro¬ 
nounced during the second half than during the first half of the period. 
That is to say, the differences existing in 1905 have well been maintained, 
considering the changes of soils and seasons, but they have not been de¬ 
cidedly increaeds since 1905 by the selections for chemical composition. 
