ctive to
the active state, the other is not.

But this is not at all the inference which has been drawn from
experiments with the mineral solution.

Seeing its ability to nourish bacteria when once inoculated with the
living active organism, and observing that no bacteria appeared in the
solution after long exposure to the air, the inference was drawn that
neither bacteria nor their germs existed in the air. Throughout
Germany the ablest literature of the subject, even that opposed to
heterogeny, is infected with this error; while heterogenists at home
and abroad have based upon it a triumphant demonstration of, their
doctrine. It is proved, they say, by the deportment of the mineral
solution that neither bacteria nor their germs exist in the air;
hence, if, on exposing a thoroughly sterilised turnip infusion to the
air, bacteria appear, they must of necessity have been spontaneously
generated. In the words of Dr. Bastian: 'We can only infer that whilst
the boiled saline solution is quite incapable of engendering bacteria,
such organisms are able to arise _de novo_ in the boiled organic
infusion.' [Footnote: 'Proceedings of the Royal Society,' vol. xxi. p.
130.]

I would ask my eminent colleague what he thinks of this reasoning now?
The datum is--'A mineral solution exposed to common air does not
develope bacteria;' the inference is--'Therefore if a turnip infusion
similarly exposed develope bacteria, they must be spontaneously
generated.' The inference, on the face of it, is an unwarranted one.
But while as matter of logic it is inconclusive, as matter of fact it
is chimerical. London air is as surely charged with the germs of
bacteria as London chimneys are with smoke. The inference just
referred to is completely disposed of by the simple question: 'Why,
when your sterilised organic infusion is exposed to optically puree
air, should this generation of life _de novo_ utterly cease? Why should
I be able to preserve my turnip-juice side by side with your saline
solution for the three hundred and sixty-five days of the year, in
free connection with the general atmosphere, on the sole condition
that the portion of that atmosphere in contact with the juice shall be
visibly free from floating dust, while three days' exposure to that
dust fills it with bacteria?' Am I over sanguine in hoping that as
regards the argument here set forth he who runs may read, and he who
reads may understand?

We now proceed to the calm an