s of both kinds existing in Bohemia
in 1860, 1865, and 1870:

1860. 1865. 1870.

High Fermentation 281 81 18

Low Fermentation 135 459 831

Thus in ten years the number of high-fermentation breweries fell from
281 to 18, while the number of low-fermentation breweries rose from
135 to 831. The sole reason for this vast change--a change which
involves a great expenditure of time, labour, and money--is the
additional command which it gives the brewer over the fortuitous
ferments of disease. These ferments, which, it is to be remembered,
are living organisms, have their activity suspended by temperatures
below 10 deg.C, and as long as they are reduced to torpor the beer remains
untainted either by acidity or putrefaction. The beer of low
fermentation is brewed in winter, and kept in cool cellars; the brewer
being thus enabled to dispose of it at his leisure, instead of forcing
its consumption to avoid the loss involved in its alteration if kept
too long. Hops, it may be remarked, act to some extent as an
antiseptic to beer. The essential oil of the hop is bactericidal:
hence the strong impregnation with hop juice of all beer intended for
exportation.

These low organisms, which one might be disposed to regard as the
beginnings of life, were we not warned that the microscope, precious
and perfect as it is, has no power to show us the real beginnings of
life, are by no means purely useless or purely mischievous in the
economy of nature. They are only noxious when out of their proper
place. They exercise a useful and valuable function as the burners
and consumers of dead matter, animal and vegetable, reducing such
matter, with a rapidity otherwise unattainable, to innocent carbonic
acid and water. Furthermore, they are not all alike, and it is only
restricted classes of them that are really dangerous to man. One
difference in their habits is worthy of special reference here. Air,
or rather the oxygen of the air, which is absolutely necessary to the
support of the bacteria of putrefaction, is, according to Pasteur,
absolutely deadly to the vibrios which provoke the butyric acid
fermentation. This has been illustrated by the following beautiful
observation.

A drop of the liquid containing those small organisms is placed upon
glass, and on the drop is placed a circle of exceedingly thin glass;
for, to magnify them sufficiently, it is necessary that the
obje