d upon the relation of the germ to its
encompassing liquid. Anything that hinders this interchange retards
the destruction of the germ in boiling water. In my paper published
in the 'Philosophical Transactions' for 1877, I add the following
remark:

It is not difficult to see that the surface of a seed or germ may be
so affected by desiccation and other causes as practically to prevent
contact between it and the surrounding liquid. The body of a germ,
moreover, may be so indurated by time and dryness as to resist
powerfully the insinuation of water between its constituent molecules.
It would be difficult to cause such a germ to imbibe the moisture
necessary to produce the swelling and softening which precede its
destruction in a liquid of high temperature.

*****

However this may be--whatever be the state of the surface, or of the
body, of the spores of Bacillus subtilis, they do as a matter of
certainty resist, under some circumstances, exposure for hours to the
heat of boiling water. No theoretic scepticism can successfully stand
in the way of this fact, established as it has been by hundreds, if
not thousands, of rigidly conducted experiments.

*****

We have now to test one of the principal foundations of the doctrine
of spontaneous generation as formulated in this country. With this
view, I place before my friend and co-enquirer two liquids which have
been kept for six months in one of our sealed chambers, exposed to
optically pure air. The one is a mineral solution containing in proper
proportions all the substances which enter into the composition of
bacteria, the other is an infusion of turnip-it might be any one of a
hundred other infusions, animal or vegetable. Both liquids are as
clear as distilled water, and there is no trace of life in either of
them. They are, in fact, completely sterilised. A mutton-chop, over
which a little water has been poured to keep its juices from drying
up, has lain for three days upon a plate in our warm room. It smells
offensively. Placing a drop of the fetid mutton-juice under a
microscope, it is found swarming with the bacteria of putrefaction.
With a speck of the swarming liquid I inoculate the clear mineral
solution and the clear turnip infusion, as a surgeon might inoculate
an infant with vaccine lymph. In four-and-twenty hours the transparent
liquids have become turbid throughout, and instead of being barren as
at first they are teeming with life. The experimen