mycelial filaments are slender, branching, and inter-
twined, but when it becomes a ferment as the result of
an insufficient supply of air, the hyphô segment, sepa-
rate, enlarge, and finally are transformed into chains
of large, round, or slightly oval cells ( Fig. 16 ) which,
in reality, resemble large cells of yeast. Bail had be-
lieved in their transformation, but Pasteur shows that
when these supposed yeasts are introduced into aôrated
must of beer they do not produce alcoholic fermenta-
tion: they reproduce the Mucor. There has not, there-
fore, been any transformation of species; there has
been only an adaptation to a new life, with a change of
form corresponding to change of functions.

When he had reached this point, Pasteur might recall
that there are analogous changes in the mycoderma of
wine when submerged in a sugar solution. The cell
becomes more turgescent, its protoplasm less granular
( Fig. 13 ). The mucor and the mycoderma, so different
in form, resemble each other, therefore, in their nature.
In the case of both, and of a certain number of other
lower species, the fermenting property, that is to say
the ability to break up sugar into alcohol and carbonic
acid, appears to us, therefore, not as a specific property
but as a transitory faculty related to the conditions of
existence, and we may briefly sum up the foregoing by
saying that fermentation is life without air.

When Pasteur gave utterance to these facts before
the Academy of Sciences, he was not understood at
first, and his opponents shouted cries of victory. This
modification of form accompanying a modification
of properties was transformation, as much as that of
Hoffmann, or Turpin, or that of Darwin. No, Pasteur
unceasingly repeated, it is not a question of a trans-
formation of species but of a general physiological law
which is applicable alike to all living species and respects

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