of the
question, it remains only that I should speak of some of those
collateral results which have come in a very remarkable way out of the
investigation of yeast. I told you that it was very early observed that
the yeast plant consisted of a bag made up of the same material as that
which composes wood, and of an interior semifluid mass which contains
a substance, identical in its composition, in a broad sense, with
that which constitutes the flesh of animals. Subsequently, after
the structure of the yeast plant had been carefully observed, it was
discovered that all plants, high and low, are made up of separate
bags or "cells," as they are called; these bags or cells having the
composition of the pure matter of wood; having the same composition,
broadly speaking, as the sac of the yeast plant, and having in their
interior a more or less fluid substance containing a matter of the same
nature as the protein substance of the yeast plant. And therefore this
remarkable result came out--that however much a plant may differ from
an animal, yet that the essential constituent of the contents of these
various cells or sacs of which the plant is made up, the nitrogenous
protein matter, is the same in the animal as in the plant. And not only
was this gradually discovered, but it was found that these semifluid
contents of the plant cell had, in many cases, a remarkable power of
contractility quite like that of the substance of animals. And about
24 or 25 years ago, namely, about the year 1846, to the best of my
recollection, a very eminent German botanist, Hugo Von Mohl, conferred
upon this substance which is found in the interior of the plant cell,
and which is identical with the matter found in the inside of the yeast
cell, and which again contains an animal substance similar to that of
which we ourselves are made up--he conferred upon this that title of
"protoplasm," which has brought other people a great deal of trouble
since! I beg particularly to say that, because I find many people
suppose that I was the inventor of that term, whereas it has been in
existence for at least twenty-five years. And then other observers,
taking the question up, came to this astonishing conclusion (working
from this basis of the yeast), that the differences between animals and
plants are not so much in the fundamental substances which compose them,
not in the protoplasm, but in the manner in which the cells of which
their bodies are built up have