536 FRA GMENTS F SCIENCE. 
hold of you that a living thing is easily generated because 
it is small. Both the yeast-plant and the barley-plant lose 
themselves in the dim twilight of antiquity, and in this 
our day there is no more proof of the spontaneous genera- 
tion of the one, than there is of the spontaneous generation 
of the other. 
I stated a moment ago that the fermentation of grape- 
juice was spontaneous; but I was careful to add, " in what 
sense spontaneous will appear more clearly by and by." 
Now this is the sense meant. The wine-maker does not, 
like the brewer and distiller, deliberately introduce either 
yeast, or any equivalent of yeast, into his vats; he does not 
consciously "sow in them any plant, or the germ of any 
plant; indeed, he has been hitherto in ignorance whether 
plants or germs of any kind have had anything to do with 
his operations. Still, when the fermented grape-juice is 
examined, the living Torula concerned in alcoholic fermen- 
tation never fails to make its appearance. How is this? 
If no living germ has been introduced into the wine-vat, 
whence comes the life so invariably developed there? 
You may be disposed to reply, with Turpin and others, 
that in virtue of its own inherent powers, the grape-juice 
when brought into contact with the vivifying atmospheric 
oxygen, runs spontaneously and of its own accord into 
these low forms of life. I have not the slightest objection 
to this explanation, provided proper evicence can be 
adduced in support of it. But the evidence adduced in 
its favor, as far as I am acquainted with it, snaps asunder 
under the strain of scientific criticism. It is, as far as I 
can see, the evidence of men, who however keen and 
clever as observers, are not rigidly trained experimenters. 
These alone are aware of the precautions necessary in 
investigations of this delicate kind. In reference, then, 
to the life of the wine-vat, what is the decision of experi- 
ment when carried out by competent men? Let a quantity 
of the clear, filtered ", must" of the grape be so boiled as 
to destroy such germs as it may have contracted from the 
air or otherwise. In contact with germless air the uncon- 
taminated must never ferment. All the materials for 
spontaneous generation are there, but so long as there is 
no seed sown, there is no life developed, and no sign of 
that fermentation which is the concomitant of life. Nor 
need you resort to a boiled liquid. The grape is sealed by 
