248 ALCOHOL, VINEGAR, SAUER KRAUT, TOBACCO, SILAGE, FLAX 
is found to be greatly changed. This is a secondary fermentation 
of a different type. It develops a certain amount of acid, its 
chemical nature is altered, and it develops a new flavor and aroma 
which should be distinctly aromatic, without any signs of putre- 
faction or mustiness. There is found to be a considerable loss of 
material, a loss ranging from 4 per cent. to 4o percent. Thisisa 
very wide range, and shows that the method of ensilage has an 
extraordinary effect upon the product obtained. The loss is 
chiefly a loss of carbohydrates, although there is also an appreci- 
able loss of albuminoids. The loss is largely parallel to the amount 
of oxygen that finds its way into the silo, being very slight if the 
oxygen of the air be thoroughly excluded. Perfect exclusion of 
air is, then, the best means of preventing the loss. 
In a properly prepared silo the fermentative changes do not ex- 
tend beyond this, and the material will now remain sweet for 
months. The superficial layers may become decayed and ruined, 
but the central mass itself is not affected. After the feeding froma 
silo is commenced its contents must be used up somewhat rapidly, 
for various undesirable fermentative changes may set up in the 
superficial layers as they are successively exposed to the air. 
The Causes of Ensilage Fermentation.—Three different factors 
have been suggested as causes for the fermentations inside the 
silo. These are: (1) The action of bacteria. (2) Respiratory 
changes in the plant tissues. (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 heatis 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 
