t is now possible to cultivate certain
pathogenic bacteria, and by modifying the conditions under which they are
grown, to destroy their violence.

In brief, science has taught us, within certain limitations, how to
change the virulent germs of a few diseases into harmless microbes.

399. Alcoholic Fermentation and Bacteria. Men of the lowest, as well
as of the highest, type of civilization have always known that when the
sugary juice of any fruit is left to itself for a time, at a moderately
warm temperature, a change takes place under certain conditions, and the
result is a liquid which, when drank, produces a pronounced effect upon
the body. In brief, man has long known how to make for himself alcoholic
beverages, by means of which he may become intoxicated with their
poisonous ingredients.

Whether it is a degraded South Sea Islander making a crude intoxicant from
a sugary plant, a Japanese preparing his favorite alcoholic beverage from
the fermentation of rice by means of a fungus plant grown for the purpose,
a farmer of this country making cider from fermenting apple juice, or a
French expert manufacturing costly champagne by a complicated process,
the outcome and the intent are one and the same. The essential thing is
to produce an alcoholic beverage which will have a marked physiological
effect. This effect is poisonous, and is due solely to the
alcoholic ingredient, without which man would have little or no use
for the otherwise harmless liquid.

While the practical process of making some form of alcoholic beverage has
been understood for these many centuries, the real reason of this
remarkable change in a wholesome fruit juice was not known until revealed
by recent progress in chemistry, and by the use of the microscope. We know
now that the change is due to fermentation, brought about from the
influence, and by the action, of bacteria (sec. 125).

In other words, fermentation is the result of the growth of low form of
vegetable life known as an organised ferment. The ferment, whether it
be the commonly used brewer's yeast, or any other species of alcoholic
ferment, has the power to decompose or break down a large part of the
sugar present in the liquid into alcohol, which remains as a poison,
and _carbon dioxid_, which escapes more or less completely.

Thus man, ever prone to do evil, was once obliged, in his ignorance, to
make his alcoholic drinks in the crudest manner; but now he has forced
into his s