n6 
Journal of Agricultural Research 
Vol. XI, No. 4 
MEAN WEIGHT OF EARS 
In 1905 there appeared to be no significant difference in weight of ears 
between the high-protein and the high-oil strains, and no significant differ¬ 
ence between the low-protein and the low-oil. The high-protein and the 
high-oil were significantly different in weight of ears from the low-protein 
and the low-oil. These two classes seem to persist well under differences 
of season and soil, as shown by the graphs of figure 3. 
In regard to progressive changes in weight, there is no doubt that, on 
the whole, the mean weight of the ears for each strain have been less 
Fig. Graphs showing the mean circumference of the ears in the four Illinois strains of Indian com for 
11 crops, 1905-1915- 
during the second half of the period 1905-1915 than during the first half 
of the period; that this is, however, merely in response to abnormal sea¬ 
sons is shown by the fact that the ears are particularly light for the crops 
of 1911, 1913, and 1914. It is important to note that the selection for 
chemical composition has probably neither increased nor decreased sig¬ 
nificantly the differences in the mean weight of ears during the period 
1905-1915. 
MEAN NUMBER OF ROWS OF KERNELS ON EARS 
In the year 1905 there was a significant difference in the number of 
rows of kernels on ears. Figure 4 shows that the same order of magnitude 
