Note: Ferments are of two kinds: ({a}) Formed or organized
ferments. ({b}) Unorganized or structureless ferments.
The latter are also called {soluble or chemical
ferments}, and {enzymes}. Ferments of the first class
are as a rule simple microscopic vegetable organisms,
and the fermentations which they engender are due to
their growth and development; as, the {acetic ferment},
the {butyric ferment}, etc. See {Fermentation}.
Ferments of the second class, on the other hand, are
chemical substances, as a rule soluble in glycerin and
precipitated by alcohol. In action they are catalytic
and, mainly, hydrolytic. Good examples are pepsin of
the dastric juice, ptyalin of the salvia, and disease
of malt.