eneration arose from nothing more than the deposition of
the germs of organisms which were constantly floating in the air.

To this conclusion, however, the objection was made, that if that were
the cause, then the air would contain such an enormous number of these
germs, that it would be a continual fog. But M. Pasteur replied that
they are not there in anything like the number we might suppose, and
that an exaggerated view has been held on that subject; he showed that
the chances of animal or vegetable life appearing in infusions, depend
entirely on the conditions under which they are exposed. If they are
exposed to the ordinary atmosphere around us, why, of course, you may
have organisms appearing early. But, on the other hand, if they are
exposed to air from a great height, or from some very quiet cellar, you
will often not find a single trace of life.

So that M. Pasteur arrived at last at the clear and definite result,
that all these appearances are like the case of the worms in the piece
of meat, which was refuted by Redi, simply germs carried by the air and
deposited in the liquids in which they afterwards appear. For my own
part, I conceive that, with the particulars of M. Pasteur's experiments
before us, we cannot fail to arrive at his conclusions; and that the
doctrine of spontaneous generation has received a final 'coup de grace'.

You, of course, understand that all this in no way interferes with the
POSSIBILITY of the fabrication of organic matters by the direct method
to which I have referred, remote as that possibility may be.

End of The Origination of Living Beings.

THE PERPETUATION OF LIVING BEINGS, HEREDITARY TRANSMISSION AND
VARIATION.

The inquiry which we undertook, at our last meeting, into the state of
our knowledge of the causes of the phenomena of organic nature,--of the
past and of the present,--resolved itself into two subsidiary inquiries:
the first was, whether we know anything, either historically or
experimentally, of the mode of origin of living beings; the second
subsidiary inquiry was, whether, granting the origin, we know anything
about the perpetuation and modifications of the forms of organic beings.
The reply which I had to give to the first question was altogether
negative, and the chief result of my last lecture was, that, neither
historically nor experimentally, do we at present know anything
whatsoever about the origin of living forms. We saw that, histori