366 
Journal of Agricultural Research 
Vol. VIII, No. io 
Table II .—Silage heated and inoculated 
[Data on ioo c. c. of juicej 
Kind of silage. 
Total 
acidity 
(NJiq). 
Volatile 
acidity 
(Nho). 
Alcohol. 
NHa-N 
Green com. 
C. c. 
C. c. 
i. 8 
xx8. 0 
Gm. 
Gm. 
Normal silage (control). 
375 
274 
0 
.265 
• 343 
0. 044 
Com heated to 8o° and inoculated. 
123.6 
*135 
Green com. 
43 
318 
198 
Normal silage. 
109. 6 
99.1 
. 150 
.244 
. HI 
. 214 
.068 
Com heated to 90° and inoculated. 
Green com. 
rrt e 
. 024 
Normal silage. 
2 /f 0 e 
73-i 
58-4 
.297 
.188 
Com heated to 85° and inoculated. 
301.5 
• JI 4 
■ °35 
The prominent part which may be played by yeasts in the fermentation 
of silage under certain conditions was demonstrated by adding to a jar 
of silage sufficient tartaric acid in solution to make 2 per cent of the 
weight of the silage. An acid mixture of this strength practically 
inhibits bacterial action and favors the development of yeasts. A com¬ 
parison of the acidity of the silage with the amount of tartaric acid added 
showed that evidently no other acid had been formed, except some vola¬ 
tile acid, which might possibly have come from the oxidation of alcohol. 
The quantity of alcohol found in 100 c. c. of this silage juice was 1.746 
gm., expressed as ethyl alcohol, while normal silage juice contains only 
from 0.20 to 0.45 gm. 
RATE OF CHEMICAL CHANGES IN SILAGE FERMENTATION 
A more conclusive method of differentiating between the activities of 
enzyms and of microorganisms was suggested by a paper by Rahn (16), 
who discussed the usefulness of curves in the interpretation of microbial 
and biochemical processes. It is shown by Rahn that the curve which 
is obtained when the formation of products of fermentation or other 
biochemical process is plotted, taking as abscissae the total time elapsed 
and as ordinates the total amounts of compounds produced, is in many 
cases indicative of the nature or cause of the change. If the change is 
caused by enzymic action and is, therefore, purely chemical, the active 
mass of the agent causing the change does not increase as the reaction 
progresses; and the decreasing concentration of the substance acted 
upon and the accumulation of end products tend to decrease the rate of 
change. Thus, the curve becomes convex toward the Y axis. The mass 
of enzym does not increase unless there are living cells present to elaborate 
more enzym. However, if organisms are present and are active, they 
multiply until the exhaustion of nutrients or the accumulation of end 
products retards and finally stops their increase. Until this time the 
