SILAGE 240 
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 bota- 
nists 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 
respiratory changes as long as they are alive and have oxygen at 
their command. This results in the gradual oxidation of the car- 
bohydrate 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 phe- 
nomenon. 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 
experimental jars in which chloroform vapor prevents the growth 
of bacteria, although it allows the enzyme action to continue as 
usual. It goes through a fermentation that is fairly typical, a fact 
that shows that the essential phenomena of ensiling may be wholly 
the result of these two sets of activities. 
The Action of Microérganisms.—It was first thought that the 
fermentation of silage was a bacterial action wholly, but further 
study showed the fallacy of this conception. The original fer- 
