of
nutrition; it followed the increase and growth of the little rods.
The next step was the discovery of the ferment of butyric acid, a
species of vibrio consisting of little rods united in chains of two
or three and possessed of movement. He found these vibrios lived
without air. Further experiments showed there were ferments to which
air was necessary, called by Pasteur the _aerobics_, and others to
whom oxygen was fatal, the _anaerobics_. He proved, also, by an
exhaustive series of experiments, that what is called putrefaction
of animal matter is the result of the combined work of the _aerobics_
and the _anaerobics_, which reduce that part not taken up by oxygen
to dead organic matter, ready in its turn to form food for living
things.

His attention having been turned to the needs of the vinegar makers
of Orleans, Pasteur began the examination of the ferment which
produces vinegar from wine. He found this in the mycoderm aceto, a
mould-like plant which has the power of developing acetic acid from
alcohol. As the result of his investigation, the manufacturers of
vinegar in France were able to do away with the cumbrous process
they had long followed, and to make vinegar, not only more cheaply,
but of very much better quality. But during these experiments
Pasteur found the temperature of 65 deg. C. was sufficient to kill the
mycoderm. When, then, the wine makers of France appealed to him to
investigate the "diseases" of wine, he was ready for the work.

Before this, however, he had examined the claims of Pouchet and
others to their alleged discovery of spontaneous generation; in
other words, the production of life. Ranging himself against them,
Pasteur showed their experiments not to have been conclusive, simply
because they had not succeeded in excluding the dust which contained
germs of life in the shape of spores of microscopic plants.

The "diseases" of wine produce sour wine, wine that "spirits,"
"greasy" wine, and bitter wine. Pasteur found each to be due to a
different microscopic ferment, all of which could be killed by heat.
He placed bottles of wine in a bath heated to 60 deg. C., and invited
the most experienced wine tasters of Paris to try them afterward.
The result of the test was the unanimous verdict that the wines had
not been injured in the least, and to-day these "diseases" of wine
are a thing of the past.

There are departments in France where the culture of the silk-worm
is the principal indus