hings and made the astounding discovery
that they were bodies which were constantly being reproduced and
growing; than when one of these rounded bodies was once formed and had
grown to its full size, it immediately began to give off a little bud
from one side, and then that bud grew out until it had attained the
full size of the first, and that, in this way, the yeast particle was
undergoing a process of multiplication by budding, just as effectual and
just as complete as the process of multiplication of a plant by
budding; and thus this Frenchman, Cagniard de la Tour, arrived at
the conclusion--very creditable to his sagacity, and which has been
confirmed by every observation and reasoning since--that this apparently
muddy refuse was neither more nor less than a mass of plants, of minute
living plants, growing and multiplying in the sugary fluid in which the
yeast is formed. And from that time forth we have known this substance
which forms the scum and the lees as the yeast plant; and it has
received a scientific name--which I may use without thinking of it,
and which I will therefore give you--namely, "Torula." Well, this was a
capital discovery. The next thing to do was to make out how this torula
was related to the other plants. I won't weary you with the whole course
of investigation, but I may sum up its results, and they are these--that
the torula is a particular kind of a fungus, a particular state
rather, of a fungus or mould. There are many moulds which under certain
conditions give rise to this torula condition, to a substance which is
not distinguishable from yeast, and which has the same properties as
yeast--that is to say, which is able to decompose sugar in the curious
way that we shall consider by-and-by. So that the yeast plant is a plant
belonging to a group of the Fungi, multiplying and growing and living in
this very remarkable manner in the sugary fluid which is, so to speak,
the nidus or home of the yeast.

That, in a few words, is, as far as investigation--by the help of one's
eye and by the help of the microscope--has taken us. But now there is an
observer whose methods of observation are more refined than those of men
who use their eye, even though it be aided by the microscope; a man who
sees indirectly further than we can see directly--that is, the chemist;
and the chemist took up this question, and his discovery was not less
remarkable than that of the microscopist. The chemist discovered that