found himself led quite naturally to think of fermenta-
tion as a vital act.

Instinctively, for it was still only instinct, he took his
stand by the side of Cagniard-Latour and the vitalists.
But, in order to defend his position, it was necessary for
him to resort to experiment.

In collating the dates of his different publications, it is
evident that he began at nearly the same time the study
of the lactic fermentation and the alcoholic. Why did
he devote his first work to the lactic fermentation, a
much less important one from the industrial point of
view? Without his telling us, it is easy to divine. In
the first place, when the fermentation becomes lactic
there is produced, in the greatest abundance, this mys-
terious amyl alcohol of which we have just spoken. But,
from his point of view, there is another deeper reason,
that is, that the alcoholic fermentation had already lost
its bloom. Liebig and the most determined of his
partisans had almost condemned it by admitting that
the yeast was necessary, and that it might be a living
organism. Their great argument, as we have said above,
was always: what rôle would you wish us to attribute to
the yeast, when we see so many other related fermenta-
tions, the lactic fermentation for example, taking place
without it, and without anything which resembles it?

The lactic fermentation was, therefore, in a certain
sense, le champ clos on which he must struggle, and I
believe I am so much the more in the right in attributing
to Pasteur this order of ideas because his argument is
confined to the following: All that one does with the
yeast, I do with the grayish deposit which I find at the
bottom of my flasks in which lactic fermentation is going
on. The yeast has an organized aspect: my ferment has
also, but it is different and difficult to see, and you have
not been able to recognize it because, owing to your idea

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