ever made its appearance in a grave scientific journal[1], may be
untenable, the fact that the _Torulae_ are alive, and that yeast does
not excite fermentation unless it contains living _Torulae_, stands
fast. Moreover, of late years, the essential participation of living
organisms in fermentation other than the alcoholic, has been clearly
made out by Pasteur and other chemists.

[Footnote 1: "Das enträthselte Geheimniss der geistigen Gährung
(Vorläufige briefliche Mittheilung)" is the title of an anonymous
contribution, to Wöhler and Liebig's "Annalen der Pharmacie" for
1839, in which a somewhat Rabelaisian imaginary description of the
organization of the "yeast animals" and of the manner in which their
functions are performed, is given with a circumstantiality worthy
of the author of Gulliver's Travels. As a specimen of the writer's
humour, his account of what happens when fermentation comes to an end
may suffice. "Sobald nämlich die Thiere keinen Zucker mehr vorfinden,
so fressen sie sich gegenseitig selbst auf, was durch eine eigene
Manipulation geschicht; alles wird verdaut bis auf die Eier, welche
unverändert durch den Darmkanal hineingehen; man hat zuletzt wieder
gährungsfähige Hefe, nämlich den Saamen der Thiere, der übrig
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