14 BULLETIN 1321, U..S. DEPARTMENT OF AGRICULTURE 
The total correlations between yield and butt circumference are 
positive, but only that in C. I. No. 133 is significant. The varietal 
difference indicated extends through the partial correlations, larger 
butt circumference apparently being desirable in C. I. No. 133. All 
of the correlations between yield and butt circumference for constant 
number of rows are positive and are the largest between this character 
and yield. In spite of the fact that only two are significant, this indi- 
cates that a larger butt circumference is more desirable when it is | 
unaccompanied by an increase in the number of rows of kernels. ~ 
One interesting correlation is that between yield and butt circum- 
ference for constant tip circumference in C. J. No. 119. Inasmuch 
as butt and tip circumference are correlated positively, this positive © 
partial correlation indicates that the less cylindrical ears perhaps were | 
the more productive in C. I. No. 119. | 
Only two of the correlations between yield and tip circumference 
are significant. That for constant weight of ear in C. I. No. 119 is 
negative, and that for constant number of rows in C. I. No. 77 is 
positive. There is nothing in the data to show any particular re- 
lation between yield and tip circumference. 
The correlations between yield and weight of cob are much like 
those for yield with weight and length of ear. The total correlations 
between yield and weight of cob are perhaps the most consistent of | 
any in the varieties as a whole. Only in C. I. No. 119 is the coeffi- | 
cient nonsignificant. In C. I. No. 77 the only positive correlation | 
between yield and any character when weight of cob is constant is 
that with percentage of grain. In this variety, therefore, weight of 
cob is more important in relation to yield than weight of ear or any of | 
its other factors. In the other varieties weight of ear apparently is — 
more important. 
The correlations between yield and percentage of grain are neither 
significant nor consistent except when weight of cob is constant. 
The data do not indicate any important relation between yield and 
percentage of grain, as such. 
The total correlations between yield and number of kernel rows are 
negative in three varieties, being significant in two. ‘The coefficient 
for this relation in C. I. No. 120, which had a mean of only 13 rows, 
is negligible. With the exception of C. I. No. 120 the correlations 
between yield and number of rows are negative throughout. When 
butt circumference is made constant the correlations are negative in 
all four varieties and significant in three of them. In connection 
with the positive correlations between yield and butt circumference 
for constant number of rows there is every indication that larger 
numbers of kernel rows are unfavorable to yield but that this is 
offset to some extent by the fact that a larger circumference, which 
usually accompanies an increase in the number of rows, is favorable 
to yield. That the correlations in C. I. No. 120 are nonsignificant 
throughout indicates that the relation between yield and number of 
rows is not rectilinear and that the number of rows in C. I. No..120 
is near the lower limit for this relation. 
The relations between yield and number of kernels per row are much 
the same as those between yield and number of rows. ‘The total 
correlations mean little because the number of kernels per row is 
