SILAGE. 231 
changes in the plant tissues, and 3. The action of enzymes. The 
probability is that, as in the other cases where there has been a 
similar dispute, all three processes are concerned. 
Respiratory Changes. The living plant cell is always carrying 
on the physiological process of respiration, a process quite similar 
to respiration in animals, and resulting in the use of oxygen and the 
evolution of carbon dioxid. In this respiration carbohydrate 
bodies are used, with some albuminoids as well, and heat is evolved. 
Now, the plant cells do not die when the plant is cut down, but con- 
tinue for some considerable time to carry on this process of respira- 
tion. Cutting the plant to pieces appears, indeed, to increase 
temporarily rather than to decrease the respiratory changes. 
These may go on for several days, until, indeed, the plant cells are 
fully dead. These are well-known facts, and recognized by botanists 
for a long time. To these respiratory changes is due part of the 
fermentation in silage. After the material is packed in the silo the 
plant cells remain alive for several days and carry on these respira- 
tory changes as long as they are alive and have oxygen at their com- 
mand. This results in the gradual oxidation of the carbohydrate 
material and the evolution of carbon dioxid. These changes are 
thought to be fully sufficient to explain the first changes in the 
silage, with the initial heating and evolution of gas. 
Fermentations Due to Enzymes. As already noticed, living plant 
tissues secrete a variety of enzymes with varying powers of acting 
upon carbohydrates and albuminoids. Such enzymes are present 
in the corn stalks and fruit, and when these are packed in the silo, 
the enzymes are of course stowed away with them. As the mass is 
warmed up under the action of the respiratory process it is inevitable 
that the enzymes will begin their action, and that the fermentations 
occurring during the next few weeks will be affected by these 
enzyme activities. It has as yet been impossible to say to what 
extent the enzyme action is concerned in the phenomenon. Certainly 
they must have much to do with the result. 
The respiratory processes and the action of the enzymes to- 
gether are capable of producing silage of ordinary type without the 
aid of bacteria or other living agencies. Silage can be made in 
