FERMENTATIONS NOT ALL DUE TO MICROORGANISMS 37 
in fermentable bodies. At one time it was thought that they were 
purely chemical processes; but this has been disproved by showing 
that living organisms are necessary to their production. Pasteur 
thought they were due to “‘life without oxygen,” claiming that the 
living germ required oxygen for its life, that if it did not find plenty 
of free oxygen, it would take atoms of this element out of the sugar 
molecules or other fermentable body, and that the withdrawal of 
this oxygen caused the molecule to fall to pieces. This theory has 
also been abandoned. ‘The theory that all living fermenting 
agents secrete a chemical enzyme appears to stand the test of 
experiment, but it explains little, for we do not know what enzy- 
mes are and we have absolutely no knowledge of how they act. 
Are they wholly lifeless chemical bodies or are they semzliving, as 
some would say? Whatever they are, they are still as great mys- 
teries as the fermentations they produce have always been. The 
real nature of the fermenting processes is, in short, quite unknown. 
FERMENTATIONS NOT ALL DUE TO MICRO- 
ORGANISMS 
One final question needs to be raised. Are all of the many 
kinds of slow progressive changes, resembling fermentations in a 
broad sense, due to the action of microdrganisms, either by direct 
action or through the agency of the enzymes they produce? After 
we have recognized that higher plants may produce enzymes, we 
see at once that there may be certain fermentative processes in the 
soil or elsewhere, for which microdrganisms are not directly re- 
sponsible. If a plant produces an enzyme, this body may remain 
ready for action after the plant which produced it is dead, and 
fermentative changes may go on in a mass of vegetable tissue for 
which microédrganisms are not responsible. It very commonly 
happens that after the death of the plant it undergoes some kind 
of fermentative change. When piled into a compost heap or 
stored in a silo, the plant tissues certainly show unquestionable 
