question, there are also a step or two to be noticed. The first step was
Dujardin’s discovery of sarcode; and the second the introduction of the
term protoplasm as the name for the layer of the _vegetable_ cell that
lined the cellulose, and enclosed the nucleus. Sarcode, found in certain
of the lower forms of life, was a simple substance that exhibited powers
of spontaneous contraction and movement. Thus, processes of such simple,
soft, contractile matter are protruded by the rhizopods, and locomotion
by their means effected. Remak first extended the use of the term
protoplasm from the layer which bore that name in the vegetable cell to
the analogous element in the animal cell; but it was Max Schultze, in
particular, who, by applying the name to the intracellular matrix, or
contained matter, when divested of membrane, and by identifying this
substance itself with sarcode, first fairly established protoplasm, name
and thing, in its present prominence.
In this account I have necessarily omitted many subordinate and
intervening steps in the successive establishment of the
_contractility_, superior _importance_, and complete _isolation_ of this
thing to which, under the name of protoplasm, Mr. Huxley of late has
called such vast attention. Besides the names mentioned, there are
others of great eminence in this connection, such as Meyen, Siebold,
Reichert, Ecker, Henle, and Kölliker among the Germans; and among
ourselves, Beale and Huxley himself. John Goodsir will be mentioned
again.
We have now, perhaps, obtained a general idea of protoplasm. Brücke,
when he talks of it as “living cell-body or elementary organism,” comes
very near the leading idea of Mr. Huxley as expressed in his phrase,
“the physiological basis, or matter, of life.” Living cell-body,
elementary organism, primitive living matter—that, evidently, is the
quest of Mr. Huxley. There is aqueous matter, he would say, perhaps,
composed of hydrogen and oxygen, and it is the same thing whether in the
rain-drop or the ocean; so, similarly, there is vital matter, which,
composed of carbon, hydrogen, oxygen, and nitrogen, is the same thing
whether in cryptogams or in elephants, in animalcules or in men. What,
in fact, Mr. Huxley seeks, probably, is living protein—protein, so to
speak, struck into life. Just such appears to him to be the nature of
protoplasm, and in it he believes himself to possess at last _a living
clay_ wherewith to build the whole organic world.
The question, What is Protoplasm? is answered, then; but, for the
understanding of what is to follow, there is still one general
consideration to be premised.
Mr. Huxley’s conception of protoplasm, as we have seen, is that of
living matter, living protein; what we may call, perhaps, elementary
life-stuff. Now, is it quite certain that Mr. Huxley is correct in this
conception? Are we to understand, for example, that cells have now
definitively vanished, and left in their place only a uniform and
universal _matter_ of quite indefinite proportions? No; such an
understanding would be quite wrong. Whatever may be the opinion of the
adherents of the molecular theory of generation, it is certain that all
the great German histologists still hold by the cell, and can hardly
open their mouths without mention of it. I do not allude here to any
special adherents of either nucleus or membrane, but to the most
advanced innovators in both respects; to such men as Schultze and Brücke
and Kühne. These, as we have seen, pretty well confine their attention,
like Mr. Huxley, to the protoplasm. But they do not the less on that
account talk of the cell. For them, it is only in cells that protoplasm
exists. To their view, we cannot fancy protoplasm as so much matter in a
pot, in an ointment-box, any portion of which scooped out in an
ear-picker would be so much life-stuff, and, though a part, quite as
good as the whole. This seems to be Mr. Huxley’s conception, but it is
not theirs. A certain _measure_ goes with protoplasm to constitute it an
organism to them, and worthy of their attention. They refuse to give
consideration to any mere protoplasm-_shred_ that may not have yet
ceased, perhaps, to exhibit all sign of contractility under the
microscope, and demand a protoplasm-_cell_. In short, protoplasm is to
them still distributed into cells, and only that measure of protoplasm
is cell that is adequate to the whole group of vital manifestations.
Brücke, for example, of all innovators probably the most innovating, and
denying, or inclined to deny, both nucleus and membrane, does not
hesitate, according to Stricker, to speak still of cells as
self-complete organisms, that move and grow, that nourish and reproduce
themselves, and that perform specific function. “Omnis cellula e
cellulâ,” is the rubric they work under as much now as ever. The heart
of a turtle, they say, is not a turtle; so neither is a protoplasm-shred
a protoplasm-cell.
This, then, is the general consideration which I think it necessary to
premise; and it seems, almost of itself, to negate Mr. Huxley’s
reasonings in advance, for it warrants us in denying that physiological
clay of which all living things are but bricks baked, Mr. Huxley
intimates, and in establishing in its place cells as before—living cells
that differ infinitely the one from the other, and so differ from the
very first moment of their existence. This consideration shall not be
allowed to pre-termit, however, an examination of Mr. Huxley’s own
proofs, which will only the more and more avail to indicate the
difference suggested.
These proofs, as has been said, would, by means of the single fulcrum of
protoplasm, establish, first, the identity, and, second, the
materiality, of all vegetable and animal life. These are, shortly, the
two propositions which we have already seen, and to which, in their
order, we now pass.
All organisms, then, whether animal or vegetable, have been understood
for some time back to originate in and consist of cells; but the
progress of physiology has _seemed_ now to substitute for cells a single
matter of life, protoplasm; and it is here that Mr. Huxley sees his cue.
Mr. Huxley’s very first word is the “physical basis or matter of life;”
and he supposes “that to many the idea that there is such a thing may be
novel.” This, then, so far, is what is _new_ in Mr. Huxley’s
contribution. He seems to have said to himself, if formerly the whole
world was thought kin in an “ideal” or formal element, organization, I
shall now finally complete this identification in a “physical” or
material element, protoplasm. In short, what at this stage we are asked
to witness in the essay is, the identification of all living beings
whatever in the identity of protoplasm. As there is a single matter,
clay, which is the matter of all bricks, so there is a single matter,
protoplasm, which is the matter of all organisms. “Protoplasm is the
clay of the potter, which, bake it and paint it as he will, remains
clay, separated by artifice, and not by nature, from the commonest brick
or sun-dried clod.” Now here I cannot help stopping a moment to remark
that Mr. Huxley puts emphatically his whole soul into this sentence, and
evidently believes it to be, if we may use the word, a _clincher_. But,
after all, does it say much? or rather, does it say anything? To the
question, “Of what are you made?” the answer, for a long time now, and
by the great mass of human beings who are supposed civilized, has been
“Dust.” Dust, and the same dust, has been allowed to constitute us all.
But materialism has not on that account been the irresistible result.
Attention hitherto—and surely excusably, or even laudably in such a
case—has been given not so much to the dust as to the “potter,” and the
“artifice” by which he could so transform, or, as Mr. Huxley will have
it, _modify_ it. To ask us to say, instead of dust, clay, or even
protoplasm, is not to ask us for much, then, seeing that even to Mr.
Huxley there still remain both the “potter” and his “artifice.”
But to return: To Mr. Huxley, when he says all bricks, being made of
clay, are the same thing, we answer, Yes, undoubtedly, if they are made
of the same clay. That is, the bricks are identical if the clay is
identical; but, on the other hand, by as much as the clay differs will
the bricks differ. And, similarly, all organisms can be identified only
if their composing protoplasm can be identified. To this stake is the
argument of Mr. Huxley bound.
This argument itself takes, as we have seen, a threefold course: Mr.
Huxley will prove his position in this place by reference, firstly, to
unity of faculty; secondly, to unity of form; and thirdly, to unity of
substance. It is this course of proof, then, which we have now to
follow, but taking the question of substance, as simplest, first, and
the others later.
By substance, Mr. Huxley understands the internal or chemical
composition; and, with a mere reference to the action of reagents, he
asserts the protoplasm of all living beings to be an identical
combination of carbon, hydrogen, oxygen, and nitrogen. It is for us to
ask, then, Are all samples of protoplasm identical, first, in their
chemical composition, and, second, under the action of the various
reagents?
On the first clause, we may say, in the first place, towards a proof of
difference which will only cumulate, I hope, that, even should we grant
in all protoplasm an identity of chemical ingredients, what is called
_Allotropy_ may still have introduced no inconsiderable variety. Ozone
is not antozone, nor is oxygen either, though in chemical constitution
all are alike. In the second place, again, we may say that, with
_varying proportions_, the same component parts produce very various
results. By way of illustration, it will suffice to refer to such
different things as the proteids, gluten, albumen, fibrin, gelatine,
etc., compared with the urinary products, urea and uric acid; or with
the biliary products, glycocol, glycocolic acid, bili-rubin,
bili-verdin, etc.; and yet all these substances, varying so much the one
from the other, are, as protoplasm is, compounds of carbon, hydrogen,
oxygen, and nitrogen. But, in the third place, we are not limited to a
_may say_; we can assert the fact that all protoplasm is not chemically
identical. All the tissues of the organism are called protoplasm by Mr.
Huxley; but can we predicate chemical identity of muscle and bone, for
example? In such cases Mr. Huxley, it is true, may bring the word
“modified” into use; but the objection of modification we shall examine
later. In the mean time, we are justified, by Mr. Huxley’s very
argument, in regarding all organized tissues whatever as protoplasm; for
if these tissues are not to be identified in protoplasm, we must suppose
denied what it was his one business to affirm. And it is against that
affirmation that we point to the fact of much chemical difference
obtaining among the tissues, not only in the _proportions_ of their
fundamental elements, but also in the _addition_ (and proportions as
well) of such others as chlorine, sulphur, phosphorus, potash, soda,
lime, magnesia, iron, etc. Vast differences vitally must be legitimately
assumed for tissues that are so different chemically. But, in the fourth
place, we have the authority of the Germans for asserting that the cells
themselves—and they now, to the most advanced, are only protoplasm—do
differ chemically, some being found to contain glycogen, some
cholesterine, some protogon, and some myosin. Now such substances, let
the chemical analogy be what it may, must still be allowed to introduce
chemical difference. In the last place, Mr. Huxley’s analysis is an
analysis of _dead_ protoplasm, and indecisive, consequently, for that
which lives. Mr. Huxley betrays sensitiveness in advance to this
objection; for he seeks to rise above the sensitiveness and the
objection at once by styling the latter “frivolous.” Nevertheless the
Germans say pointedly that it is unknown whether the same elements are
to be referred to the cells after as before death. Kühne does not
consider it proved that living muscle contains syntonin; yet Mr. Huxley
tells us, in his Physiology, that “syntonin is the chief constituent of
muscle and flesh.” In general, we may say, according to Stricker, that
all weight is put now on the examination of living tissue, and that the
difference is fully allowed between that and dead tissue.
On the second clause now, or with regard to the action of reagents,
these must be denied to produce the like result on the various forms of
protoplasm. With reference to temperature, for example, Kühne reports
the movements of the amoeba to be arrested in iced water; while, in the
same medium, the ova of the trout furrow famously, but perish even in a
warmed room. Others, again, we are told, may be actually dried, and yet
live. Of ova in general, in this connection, it is said that they live
or die according as the temperature to which they are exposed differs
little or much from that which is natural to the organisms producing
them. In some, according to Max Schultze, even distilled water is enough
to arrest movement. Now, not to dwell longer here, both amoeba and ova
are to Mr. Huxley pure protoplasm; and such difference of result,
according to difference of temperature, etc., must assuredly be allowed
to point to a difference of original nature. Any conclusion so far,
then, in regard to unity of substance, whether the chemical composition
or the action of reagents be considered, cannot be said to bear out the
views of Mr. Huxley.
What now of the unities of form and power in protoplasm? By form, Mr.
Huxley will be found to mean the general appearance and structure; and
by faculty or power, the action exhibited. Now it will be very easy to
prove that, in neither respect, do all specimens of protoplasm agree.
Mr. Huxley’s representative protoplasm, it appears, is that of the
nettle-sting; and he describes it as a granulated, semi-fluid body,
contractile in mass, and contractile also in detail to the development
of a species of circulation. Stricker, again, speaks of it as a
homogeneous substance, in which any granules that may appear must be
considered of foreign importation, and in which there are no evidences
of circulation. In this last respect, then, that Mr. Huxley should talk
of “tiny Maelstroms,” such as even in the silence of a tropical noon
might stun us, if heard, as “with the roar of a great city,” may be
viewed, perhaps, as a rise into poetry beyond the occasion.
Further, according to Stricker, protoplasm varies almost infinitely in
consistence, in shape, in structure, and in function. In consistence, it
is sometimes so fluid as to be capable of forming in drops; sometimes
semi-fluid and gelatinous; sometimes of considerable resistance. In
shape—for to Stricker the cells are now protoplasm—we have club-shaped
protoplasm, globe-shaped protoplasm, cup-shaped protoplasm,
bottle-shaped protoplasm, spindle-shaped protoplasm—branched, threaded,
ciliated protoplasm,—circle-headed protoplasm—flat, conical,
cylindrical, longitudinal, prismatic, polyhedral, and palisade-like
protoplasm. In structure, again, it is sometimes uniform and sometimes
reticulated into interspaces that contain fluid. In function, lastly—and
here we have entered on the consideration of faculty or power—some
protoplasm is vagrant (so to translate _wandernd_), and of unknown use,
like the colorless blood-corpuscles.
In reference to these, as strengthening the argument, and throwing much
light generally, I break off a moment to say that, very interesting as
they are in themselves, and as Recklinghausen, in especial, has made
them, Mr. Huxley’s theory of them disagrees considerably with the
prevalent German one. He speaks of them as the source of the body in
general, yet, in his Physiology, he talks of the spleen, the lymphatics,
and even the liver—_parts_ of the body—as _their_ source. They are so
few in number that, while Mr. Huxley is thankful to be able to point to
the inside of the lips as a seat for them, they bear to the red
corpuscles only the proportion of 1 to 450. This disproportion, however,
is no bar to Mr. Huxley’s derivation of the latter from the former. But
the fact is questioned. The Germans, generally, for their, part,
describe the colorless, or vagrant, blood-corpuscles as probably media
of conjugation or reparation, but acknowledge their function to be as
yet quite unknown; while Rindfleisch, characterizing the spleen as the
grave of the red, and the womb of the white, corpuscles, evidently
refers the latter to the former. This, indeed, is a matter of direct
assertion with Preyer, who has “shown that pieces of red
blood-corpuscles may be eaten by the amoeboid cells of the frog,” and
holds that the latter (the white corpuscles) proceed directly from the
former (the red corpuscles); so that it seems to be determined in the
mean time that there is no proof of the reverse being the fact.
In function, then, to resume, some protoplasm is vagrant, and of unknown
use. Some again produces pepsine, and some fat. Some at least contains
pigment. Then there is nerve-protoplasm, brain-protoplasm,
bone-protoplasm, muscle-protoplasm, and protoplasm of all the other
tissues, no one of which but produces only its own kind, and is
uninterchangeable with the rest. Lastly, on this head, we have to point
to the overwhelming fact that there is the infinitely different
protoplasm of the various infinitely different plants and animals, in
each of which its own protoplasm, as in the case of that of the various
tissues, but produces its own kind, and is uninterchangeable with that
of the rest.
It may be objected, indeed, that these latter are examples of modified
protoplasm. The objection of modification, as said, we have to see by
itself later; but, in the mean time, it may be asked, Where are we to
begin, _not_ to have modified protoplasm? We have the example of Mr.
Huxley himself, who, in the nettle-sting, begins already with modified
protoplasm; and we have the authority of Rindfleisch for asserting that
“in every different tissue we must look for a different initial term of
the productive series.” This, evidently, is a very strong light on the
original multiplicity of protoplasm, which the consideration, as we have
seen, of the various plants and animals, has made, further, infinite.
This is enough; but there is no wish to evade beginning with the very
beginning—with absolutely pure initial protoplasm, if it can but be
given us in any reference. The simple egg—that, probably is the
beginning—that, probably, is the original identity; yet even there we
find already distribution of the identity into infinite difference.
This, certainly, with reference to the various organisms, but with
reference also to the various tissues. That we regard the egg as the
beginning, and that we do not start, like the smaller exceptional
physiological school, with molecules themselves, depends on this, that
the great Germans so often alluded to, Kühne among them, still trust in
the experiments of Pasteur; and while they do not deny the possibility,
or even the fact, of molecular generation, still feel justified in
denying the existence of any observation that yet unassailably attests a
_generatio æquivoca_. By such authority as this the simple philosophical
spectator has no choice but to take his stand; and therefore it is that
I assume the egg as the established beginning, so far, of all vegetable
and animal organisms. To the egg, too, as the beginning, Mr. Huxley,
though the lining of the nettle-sting is his representative protoplasm,
at least refers. “In the earliest condition of the human organism,” he
says, in allusion to the white (vagrant) corpuscles of the blood, “in
that state in which it has but just become distinguished from the egg in
which it arises, it is nothing but an aggregation of such corpuscles,
and every organ of the body was once no more than such an aggregation.”
Now, in beginning with the egg—an absolute beginning being denied us in
consequence of the pre-existent infinite difference of the egg or eggs
themselves—we may gather from the German physiologists some such account
of the actual facts as this.
The first change signalized in the impregnated egg seems that of
_Furchung_, or furrowing—what the Germans call the _Furchungskugeln_,
the _Dotterkugeln_, form. Then these _Kugeln_—clumps, eminences,
monticles, we may translate the word—break into cells; and these are the
cells of the embryo. Mr. Huxley, as quoted, refers to the whole body,
and every organ of the body, as at first but an aggregation of colorless
blood-corpuscles; but in the very statement which would render the
identity alone explicit, the difference is quite as plainly implicit. As
much as this lies in the word “organs,” to say nothing of “human.” The
cells of the “organs,” to which he refers, are even then
uninterchangeable, and produce but themselves. The Germans tell us of
the _Keimblatt_, the germ-leaf, in which all these organs originate.
This _Blatt_, or leaf, is threefold, it seems; but even these folds are
not indifferent. The various cells have their distinct places in them
from the first. While what in this connection are called the epithelial
and endorthelial tissues spring respectively from the _upper_ and
_under_ leaf, connective tissues, with muscle and blood, spring from the
_middle_ one. Surely in such facts we have a perfect warrant to assert
the initial non-identity of protoplasm, and to insist on this, that,
from the very earliest moment—even literally _ab ovo_—brain-cells only
generate brain-cells, bone-cells bone-cells, and so on.
These considerations on function all concern faculty or power; but we
have to notice now that the characteristic and fundamental form of power
is to Mr. Huxley _contractility_. He even quotes Goethe in proof of
contractility being the main power or faculty of _Man_! Nevertheless it
is to be said at once that, while there are differences in what
protoplasm _is_ contractile, all protoplasm is not contractile, nor
dependent on contractility for its functions. In the former respect, for
example, muscle, while it is the contractile tissue special, is also to
Mr. Huxley protoplasm; yet Stricker asserts the inner construction of
the contractile substance, of which muscle-fibre virtually consists, to
be essentially different from contractile protoplasm. Here, then, we
have the contractile _substance_ proper “essentially different” from the
contractile _source_ proper. In the latter respect, again, we shall not
call in the _un_contractible substances which Mr. Huxley himself
denominates protoplasm—bread, namely, roast mutton, and boiled lobster;
but we may ask where—even in the case of a living body—is the
contractility of white of egg? In this reference, too, we may remark
that Kühne, who divides the protoplasm of the epidermis into three
classes, has been unable to distinguish contractility in his own third
class. Lastly, where, in relation to the protoplasm of the nervous
system, is there evidence of its contractility? Has any one pretended
that thought is but the contraction of the brain; or is it by
contraction that the very nerves operate contraction—the nerves that
supply muscles, namely? Mr. Huxley himself, in his Physiology, describes
nervous action very differently. There _conduction_ is spoken of without
a hint of contraction. Of the higher faculties of man I have to speak
again; but let us just ask where, in the case of any pure
sensation—smell, taste, touch, sound, color—is there proof of any
contraction? Are we to suppose that between the physical cause of heat
without and the mental sensation of heat within, contraction is anywhere
interpolated? Generally, in conclusion here, while reminding of
Virchow’s testimony to the inherent inequalities of cell-capacity, let
us but, on the question of faculty, contrast the kidney and the brain,
even as these organs are viewed by Mr. Huxley. To him the one is but a
sieve for the extrusion of refuse: the other thinks Newton’s ‘Principia’
and Iliads of Homer.