32 FERMENTATION, PUTREFACTION, AND DECAY 
IMPORTANCE OF FERMENTATION IN FARM LIFE 
The value of all these types of fermentation in agriculture is 
evident from the following list of the most important of them. In 
the first class may be mentioned: 
The alcoholic fermentation; the butyric fermentation, which 
produces butyric acid in butter; the lactic fermentation, which 
often causes the souring of milk and various other products, and 
which is responsible for the ripening of cream; the acetic fermenta- 
tion, which produces acetic acid and forms vinegar; the proteolytic 
or pepionizing fermentation, which renders soluble certain insolu- 
ble proteids, an example of which is found in the ripening of cheese, 
the oxidizing fermentation, which causes the oxidation of organic 
matter, as in the fermentation of tobacco; the miirzfying fermenta- 
tion, which converts ammonia into nitrates or nitrites; the dentirt- 
fying fermentation, which converts nitrates into nitrites or sim- 
pler compounds by depriving them of oxygen. Then there are the 
phenomena of puirefaction and decay, which are endless in variety 
and which lie at the bottom of continued soil fertility. 
There is a much longer list of the unorganized ferments, or 
enzymes, derived from both plants and animals. Some of the 
most important are the following: 
Diastase, found in both plants and animals, which changes 
starch to sugar; inulase, which has a similar action upon inulin; 
invertase, trehalase, rafinase, melizitase, laciase, which act upon 
sugars, changing their chemical formule or, as the chemist says, 
inverting them mulsin, myrosin, erythrozym, tannase, lotase, 
and some others, which act upon chemical substances called gluco- 
sids; pepsin, trypsin, from animal digestive juices, and galactase 
from milk, together with bromelin, papain, and vegetable irypsin, 
from plants, which act upon proteids, causing them to change 
into simpler compounds. These are called proteolytic enzymes. 
Lipase acts upon fats, splitting their chemical molecules; rennet 
acts upon milk, causing it to curdle; thrombase is in the blood and 
