588 
Journal of Agricultural Research 
Vol. XXX, No. 6 
EXPERIMENTAL DATA 
MATERIAL USED 
Three corn varieties of commercial 
and agricultural importance were used 
in the experiments reported in this 
paper. 
The Four County corn variety, which 
was started with different strains of 
Silver King, has been bred since 1910 
or 1912 by the Four County Grain 
Improvement Association at Ackley, 
Iowa, under the direction of the Iowa 
Agricultural Experiment Station. 
About 100,000 acres are grown each 
year in north-central Iowa. 
United States selection No. 77, which 
is a White Dent variety, selected and 
bred by the United States Department 
of Agriculture from Woodburn’s White 
Dent, is grown in southern Ohio and 
Indiana. 
United States selection No. 193, 
which is an 8-rowed yellow flint, se¬ 
lected and developed by the United 
States Department of Agriculture from 
Hall Gold Nugget, is grown in the 
Hudson River Valley in southeastern 
New York. The corn samples were 
ground in an electric buhr-mill and 
passed through a 40-mesh sieve. 
DESCRIPTION OF METHODS 
(1) The total nitrogen content was 
estimated according to Kjeldahl’s 
method. 
(2) The protein nitrogen was esti¬ 
mated according to Stutzer’s method 
(17). 
(3) The nitrogen of amino acids was 
determined according to Sorensen’s 
method (16), as applied by the writer 
elsewhere (6, 6, 7). 
Other methods and their details will 
subsequently be described in this paper. 
From the experimental data pre¬ 
sented in Table I it will be seen that 
whereas the Four County corn is char¬ 
acterized by the highest percentage of 
total and of protein nitrogen, of dry 
substance and of ash, Hall Gold Nugget 
is characterized by the lowest percent¬ 
age of the corresponding constituents; 
the figures for United States selection 
No. 77 are between these two, with the 
exception of the dry substance, which 
is lower in United States selection No. 
77 variety than in Halt Gold Nugget. 
Table I .—Percentage of dry substance, of ash, and of total, protein, and nonprotein 
nitrogen in the ungerminated maize kernel 
