torula proceeds in our present experience, from pre-existing torulae.
These little bodies are excessively light. You can easily imagine what
must be the weight of little particles, but slightly heavier than water,
and not more than the two-thousandth or perhaps seven-thousandth of an
inch in diameter. They are capable of floating about and dancing like
motes in the sunbeam; they are carried about by all sorts of currents
of air; the great majority of them perish; but one or two, which may
chance to enter into a sugary solution, immediately enter into active
life, find there the conditions of their nourishment, increase and
multiply, and may give rise to any quantity whatever of this substance
yeast. And, whatever may be true or not be true about this
"spontaneous generation," as it is called in regard to all other kinds
of living things, it is perfectly certain, as regards yeast, that it
always owes its origin to this process of transportation or inoculation,
if you like so to call it, from some other living yeast organism; and
so far as yeast is concerned, the doctrine of spontaneous generation is
absolutely out of court. And not only so, but the yeast must be alive
in order to exert these peculiar properties. If it be crushed, if it be
heated so far that its life is destroyed, that peculiar power of
fermentation is not excited. Thus we have come to this conclusion, as
the result of our inquiry, that the fermentation of sugar, the
splitting of the sugar into alcohol and carbonic acid, glycerine, and
succinic acid, is the result of nothing but the vital activity of this
little fungus, the torula.

And now comes the further exceedingly difficult inquiry--how is it that
this plant, the torula, produces this singular operation of the
splitting up of the sugar? Fabroni, to whom I referred some time ago,
imagined that the effervescence of fermentation was produced in just the
same way as the effervescence of a sedlitz powder, that the yeast was a