sufficient to effect that small disturbance of the equilibrium of the
particles of the sugar, which Lavoisier thought sufficient to effect
its decomposition.

Platinum in a very fine state of division--known as platinum black, or
_noir de platine_--has the very singular property of causing alcohol
to change into acetic acid with great rapidity. The vinegar plant,
which is closely allied to the yeast plant, has a similar effect upon
dilute alcohol, causing it to absorb the oxygen of the air, and become
converted into vinegar; and Liebig's eminent opponent, Pasteur, who
has done so much for the theory and the practice of vinegar-making,
himself suggests that in this case--

"La cause du phénomène physique qui accompagne la vie de la
plante réside dans un état physique propre, analogue à celui
du noir de platine. Mais il est essentiel de remarquer que cet
état physique de la plante est étroitement lié avec la vie de
cette plante."[1]

[Footnote 1: "Etudes sur les Mycodermes," Comptes-Rendus, liv., 1862.]

Now, if the vinegar plant gives rise to the oxidation of alcohol,
on account of its merely physical constitution, it is at any rate
possible that the physical constitution of the yeast plant may exert a
decomposing influence on sugar.

But, without presuming to discuss a question which leads us into the
very arcana of chemistry, the present state of speculation upon the
_modus operandi_ of the yeast plant in producing fermentation is
represented, on the one hand, by the Stahlian doctrine, supported by