courtesy. If your infusions remain sterile it is because
you heat too much. You alter thus the air in the flasks,
or else you destroy the vegetative force of your liquids.
The first of these objections was acceptable, although it
lacked force and precision in an epoch when the composi-
tion of the air was still unknown. But what was to be
said of the second? The vegetative force of the liquid,
does not that recall invincibly the dormative property of
opium, ridiculed a hundred years before by Molière?
This strange conception, nevertheless, met with favor,
and, if I recall it, it is because the idea served as a banner.
If, in the discussions on spontaneous generations, there
have always been savants, who, like Spallanzani, have
endeavored never to go beyond experiment, there also
have been always those who, like Needham, have not
hesitated, in a time of great need, to have recourse to
the vegetative force, to the creative power of infusions, or to
other conceptions not less vague and chimerical. There,
as everywhere, has been the tribe of those who love to
deceive themselves with words.

Be that as it may, the celebrated debate raised be-
tween Needham and Spallanzani was left without any
definite conclusion, each of the adversaries showing
clearly that the other was wrong on some points, but not
proving that he himself was right on all. However,
science in its onward march validated or invalidated
their arguments. We have said that Gay-Lussac, by
studying the conserves of Appert, which were nothing
more than the application to domestic economy of the
results of Spallanzani, found that the air in the tins no
longer contained oxygen: this seemed to justify the first
objection of Needham given above. But in 1836, it
occurred to Schultze to replace with ordinary air the air
in the flasks of Spallanzani. After having determined
that they are sterile, he shows that they remain sterile

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