n writes:--

"Enfin, une loi sans exception me semble apparaitre dans les faits
nombreux que j'ai observes et conduire a envisager sous un nouveau jour
la vie vegetale; si je ne m'abuse, tout ce que dans les tissus vegetaux
la vue directe ou amplifiee nous permet de discerner sous la forme de
cellules et de vaisseaux, ne represente autre chose que les enveloppes
protectrices, les reservoirs et les conduits, a l'aide desquels les corps
animes qui les secretent et les faconnent, se logent, puisent et
charrient leurs aliments, deposent et isolent les matieres excretees."

And again:--

"Afin de completer aujourd'hui l'enonce du fait general, je rappellerai
que les corps, doue des fonctions accomplies dans les tissus des plantes,
sont formes des elements qui constituent, en proportion peu variable, les
organismes animaux; qu'ainsi l'on est conduit a reconnaitre une immense
unite de composition elementaire dans tous les corps vivants de la
nature."[7]

[Footnote 7: Mem. sur les Developpements des Vegetaux, &c.--_Mem.
Presentees_. ix. 1846.]

In the year (1846) in which these remarkable passages were published, the
eminent German botanist, Von Mohl invented the word "protoplasm," as a
name for one portion of those nitrogenous contents of the cells of living
plants, the close chemical resemblance of which to the essential
constituents of living animals is so strongly indicated by Payen. And
through the twenty-five years that have passed, since the matter of life
was first called protoplasm, a host of investigators, among whom Cohn,
Max Schulze, and Kuehne must be named as leaders, have accumulated
evidence, morphological, physiological, and chemical, in favour of that
"immense unite de composition elementaire dans tous les corps vivants de
la nature," into which Payen had, so early, a clear insight.

As far back as 1850, Cohn wrote, apparently without any knowledge of what
Payen had said before him:--

"The protoplasm of the botanist, and the contractile substance and
sarcode of the zoologist, must be, if not identical, yet in a high degree
analogous substances. Hence, from this point of view, the difference
between animals and plants consists in this; that, in the latter, the
contractile substance, as a primordial utricle, is enclosed within an
inert cellulose membrane, which permits it only to exhibit an internal
motion, expressed by the phenomena of rotation and circulation, while, in
the former, it is not so enclos