ed. The protoplasm in the form of the
primordial utricle is, as it were, the animal element in the plant, but
which is imprisoned, and only becomes free in the animal; or, to strip
off the metaphor which obscures simple thought, the energy of organic
vitality which is manifested in movement is especially exhibited by a
nitrogenous contractile substance, which in plants is limited and
fettered by an inert membrane, in animals not so."[8]

[Footnote 8: Cohn, "Ueber Protococcus pluvialis," in the _Nova Acta_ for
1850.]

In 1868, thinking that an untechnical statement of the views current
among the leaders of biological science might be interesting to the
general public, I gave a lecture embodying them in Edinburgh. Those who
have not made the mistake of attempting to approach biology, either by
the high _a priori_ road of mere philosophical speculation, or by the
mere low _a posteriori_ lane offered by the tube of a microscope, but
have taken the trouble to become acquainted with well-ascertained facts
and with their history, will not need to be told that in what I had to
say "as regards protoplasm" in my lecture "On the Physical Basis of Life"
(Vol. I. of these Essays, p. 130), there was nothing new; and, as I hope,
nothing that the present state of knowledge does not justify us in
believing to be true. Under these circumstances, my surprise may be
imagined, when I found, that the mere statement of facts and of views,
long familiar to me as part of the common scientific property of
Continental workers, raised a sort of storm in this country, not only by
exciting the wrath of unscientific persons whose pet prejudices they
seemed to touch, but by giving rise to quite superfluous explosions on
the part of some who should have been better informed.

Dr. Stirling, for example, made my essay the subject of a special
critical lecture,[9] which I have read with much interest, though, I
confess, the meaning of much of it remains as dark to me as does the
"Secret of Hegel" after Dr. Stirling's elaborate revelation of it. Dr.
Stirling's method of dealing with the subject is peculiar. "Protoplasm"
is a question of history, so far as it is a name; of fact, so far as it
is a thing. Dr. Stirling, has not taken the trouble to refer to the
original authorities for his history, which is consequently a travesty;
and still less has he concerned himself with looking at the facts, but
contents himself with taking them also at second-hand. A