590 
Journal of Agricultural Research 
Vol. XXX, No. 6 
Table II .—'Partition of the nonprotein nitrogen in the ungerminated maize kernel 
Variety of corn 
Nitrogen 
of acid 
amides 
Nitrogen 
of amino 
acids 
Peptide 
nitrogen 
Remarks 
Data expressed in percentage of the oven-dried 
maize kernel: 
Four County corn____ 
Per cent 
0.034 
Per cent 
0.044 
Per cent 
0.070 
Hot-water extract. 
United States selection No. 77_ 
.018 
.042 
.052 
Cold-water extract. 
Hall Gold Nugget selection No. 193 .. __ 
.021 
.052 
.035 
Hot-water extract. 
Do_ 
.022 
.050 
.039 
Cold-water extract. 
Data expressed in percentage of the total nitrogen 
of the maize kernel: 
Four County corn.__ 
2.00 
2.59 
4.12 
Hot-water extract. 
United States selection No. 77_ 
1.13 
2. 64 
3. 27 
Cold-water extract. 
Hall Gold Nugget selection No. 193_ 
1.44 
3. 56 
2 . 40 
Hot-water extract. 
Do__T____ 
1.51 
3. 43 
2. 67 
Cold-water extract. 
Data expressed in percentage of the water-soluble 
nitrogen of the maize kernel: 
Four County corn_ __ 
16. 58 
21 . 68 
34. 36 
Hot-water extract. 
United States selection No. 77 _ 
11.64 
28.11 
34.11 
Cold-water extract. 
Hall Gold Nugget, selection No. 193_ 
11.15 
27. 57 
18. 55 
Hot-water extract. 
Do______ 
11.32 
26. 51 
20 . 66 
Cold-water extract. 
the last named variety. The outstand¬ 
ing feature of Table II, in which each 
figure ordinarily represents the average 
of at least four individual estimations, 
is the fact that each of the three vari¬ 
eties contains acid amides, amino acids, 
and polypeptides in not inconsider¬ 
able quantities. From the circum¬ 
stance that the results obtained with 
the hot-water extracts do not essen¬ 
tially differ from the data secured with 
the cold-water extracts it follows that 
under the conditions of the work, 
extraction with cold water for but 
one hour and rapid evaporation of the 
extracts in vacuo , no noticeable hydrol¬ 
ysis of the proteins under the influ¬ 
ence of enzymes took place. It 
further follows that amino acids and 
polypeptides are preformed in the 
corn kernel. 
In the experiments described, the 
purification of the aqueous extracts 
was effected by means of acetic acid, 
lead hydroxide, and lead acetate. This 
treatment removes completely the 
proteins but does not remove the pro¬ 
teose quantitatively. Since the latter 
is present in the water extracts of 
corn, though in very small quantity, 
the idea suggested itself that the hy¬ 
drolysis of the polypeptides might be 
accompanied by the hydrolysis of the 
proteose, in which case the results re¬ 
ported for the polypeptides might be 
somewhat too high (see the fourth 
column of Table II). Hence, it 
seemed necessary to remove quantita¬ 
tively the proteose along with the pro¬ 
teins before hydrolysis takes place. 
This was accomplished by the use of 
phosphotungstic acid. The dry resi¬ 
due of the alcoholic extract of a known 
quantity of flour was dissolved in 
water and made up to a definite 
volume, usually to 100 c. c. or its 
multiple. After determining the nitro¬ 
gen by the Kjeldahl method in a 
small portion, the bulk of the solution 
was treated with 5 gm. of sulphuric 
acid mixed with 30 c. c. of a solution 
containing 20 gm. of phosphotungstic 
acid and 5 gm. of sulphuric acid per 
100 c. c. In each case it was ascer¬ 
tained that a slight excess of the pre¬ 
cipitant was used. The precipitates 
formed were filtered, after 24 hours, 
and washed with a solution made up 
of 2.5 gm. of phosphotungstic acid and 
5 gm. of sulphuric acid per 100 c. c. 
The quantity of nitrogen present in 
the phosphotungstic precipitate was 
estimated by the Kjeldahl method. 
The filtrate from phosphotungstic acid 
precipitate was treated with calcium 
hydroxide to slight acidity, then with 
barium hydroxide to slight alkalinity, 
whereupon it was saturated with car¬ 
bon dioxide, the whole heated to boil¬ 
ing, filtered, and thoroughly washed 
with hot ammonia-free water. The 
filtrate and washings from the phos- 
photungstate, sulphate, and carbonate 
of calcium and barium were evapor¬ 
ated in a vacuum, made up to a definite 
volume, and the amino nitrogen esti¬ 
mated by formol titration, while the 
peptide nitrogen was determined, on 
hydrolysis, as already outlined. The 
results secured are summarized in 
Table III. 
A glance at Table III shows that the 
prevalent quantity of nitrogen is pres¬ 
ent in the phsophotungstic acid pre¬ 
cipitate which contains the proteins, 
proteose, and any basic compounds oc¬ 
curring in maize, while the nitrogen 
proportions of the polypeptides, amino 
acids, and acid amides follow in the 
order named, with the exception of 
Hall Gold Nugget selection 193, in 
which the proportion of amino acids is 
