23 
Nitrogen content ofzeinfrom maize and its bacterial decomposition products. 
• 
Per cent of original 
material. 
Per cent of total N. 
Per cent of 
groups de- 
composed. 
Per cent of 
organic N 
after bacte- 
rial action. 
Before. 
After. 
Before. 
After. 
Ammonia N 
0.98 
2.21 
.38 
10.46 
6.98 
15.75 
2.78 
74.55 
AmidN 
2.75 
.43 
10.85 
19.60 
3.06 
77.33 
19.64 
11.63 
3.59 
16.93 
2 91 
Nonbasic N 
80.15 
Bacterial action was allowed to continue for three days, but, as 
shown in the table, only small amounts of ammonia were formed. 
The zein as prepared was in a tough, horny condition, and was conse- 
quently difficult to pulverize, which probably accounts in part for the 
low yields of ammonia. The data show that the basic diamino acids 
were only decomposed to a slight extent; but in this case the amids 
were most markedly decomposed. The decreases in amid nitrogen 
as determined, however, may not have been entirely due to ammoni- 
fication, since any amid compounds that were split off by the bac- 
teria, but not ammonified, would have been decomposed and deter- 
mined as ammonia along with that actually formed by the bacteria. 
As shown above, a large portion of the nitrogen in the materials 
used was not ammonified, or at least did not occur at any one time as 
ammonia; neither was the yield of ammonia from casein in the experi- 
ments with soil materially increased by prolonging the time of decom- 
position beyond four days. But the cessation of ammonification was 
not due to the accumulation of poisonous by-products, since the 
second and third grams, added after the ammonification of one gram 
had come to a stop, were each ammonified to a slightly greater extent 
than the first gram. It seems probable, therefore, that a part of the 
organic nitrogen in the materials used is more resistant to ammoni- 
fication than others. It should also be remembered that putrefac- 
tive decomposition usually takes place to some extent in the ordinary 
ammonification experiment, which probably results in the formation 
of the aromatic protein cleavage products, tyrosin, phenylalanin, and 
tryptophane at first; later these are decomposed into indol and 
skatol, rather than being immediately converted into ammonia. It 
seems also that a portion of the nitrogen was assimilated by the 
organisms present, but whether the assimilation of ammonia or 
organic forms took place can not be definitely stated. The latter 
seems the more probable. In either case it is reasonably certain that 
synthesis as well as decomposition plays a considerable part in the 
chemistry of soil organic nitrogen. 
Finally the basic diamino nitrogen of organic materials is ammoni- 
fied, or otherwise loses its identity as such more rapidly than the 
