n geschicht; alles wird verdaut bis auf die Eier, welche
unveraendert durch den Darmkanal hineingehen; man hat zuletzt wieder
gaehrungsfaehige Hefe, naemlich den Saamen der Thiere, der uebrig
bleibt."]

However, it may be asked, is there any necessary opposition between
the so-called "vital" and the strictly physico-chemical views of
fermentation? It is quite possible that the living _Torula_ may excite
fermentation in sugar, because it constantly produces, as an essential
part of its vital manifestations, some substance which acts upon the
sugar, just as the synaptase acts upon the amygdalin. Or it may
be, that, without the formation of any such special substance,
the physical condition of the living tissue of the yeast plant is
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 phenomene physique qui accompagne la vie de la
plante reside dans un etat physique propre, analogue a celui
du noir de platine. Mais il est essentiel de remarquer que cet
etat physique de la plante est etroitement lie 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
Liebig, according to which the atoms of the sugar are shaken into new
combinations, either directly by the _Torulae_, or indirectly, by some
substance formed by them; and