As further witnesses to the passing of Darwinism, two botanists may be
cited; the first is Professor Korschinsky who in No. 24, 1899, of the
_Naturwissenschaftliche Wochenschrift_ published an article on
"Heterogenesis and Evolution," which was to be followed later by a
large work on this subject. With precision and emphasis he points to
the numerous instances in which there occurs on or in a plant, suddenly
and without intervention, a variation which may become hereditary under
certain circumstances; thus during the last century a number of
varieties of garden plants have been evolved. On the basis of such
experiments Korschinsky developed the theory which had been proposed by
Koelliker in Wuerzburg thirty years earlier, namely, the theory of
"heterogeneous production" or "heterogenesis," as Korschinsky calls it.
When one understands that a plant gives rise suddenly and without any
intervention to a grain of seed, which produces a different plant, it
becomes evident that all Darwinistic speculations about selection and
struggle for existence are forthwith absolutely excluded. The effect
can proceed only from the internal vital powers inherent in the
specified organism acting in connection, perhaps, with the internal
conditions of life, which suddenly exert an influence in a new
direction.
Korschinsky distinguishes clearly and definitely between the principles
of Heterogenesis and Transmutation (gradual transformation through
natural selection in the struggle for existence), and in so doing comes
to a complete denial of Darwinism.
The other naturalist who has dealt Darwinism a telling blow is the
botanist of Graz, Professor Haberlandt.
He published some very interesting observations and experiments in the
"Festschrift fuer Schwendener" (Berlin 1899, Borntraeger). They are
concerned with a Liane javas of the family of mulberry plants
(Conocephalus ovatus.) The free leaves possess under the outer layer, a
tissue composed of large, thin-walled, water-storing cells; flat
cavities on the upper side, having, furthermore, organs that secrete
water, which the botanist calls hydathodes. These are delicate, small,
glandular cells over which are the bundles of vascular fibres
(leaf-veins) that convey the water to them; over these in the top layer
are so-called water-crevices through which the water can force itself
to the outside. It is unnecessary to enter upon a closer explanation of
the anatomical structure of these peculiar organs. The water which is
forced upward by the root-pressure of the plant is naturally conveyed
through the vascular fibres into the leaves and at every hydathode the
superfluous water oozes out in drops, a phenomenon which one can also
very nicely observe e.g. on the "Lady's cloak" (Alchemilla vulgaris) of
the German flora. A portion of the night-dew must be attributed to this
secretion of water. On the Liane, then, Haberlandt observed a very
considerable secretion of water: a full-grown leaf secreted during one
night 2.76 g. of water (that is 26 per cent. of its own weight.)
Through this peculiarity the water supply within the plant is regulated
and the danger avoided that any water should penetrate the surrounding
tissue in consequence of strong root-pressure,--which would naturally
obstruct the vital function of the entire leaf. Besides it is to be
noticed that in this way an abundant flow of water is produced: the
plant takes up large quantities of water from the earth, laden with
nutritive salts, and the distilled water is almost pure (it contains
only 0.045 g. salts), so that the nutritive salts are absorbed by the
plant.
From these considerations it necessarily appears that the hydathodes
are of great biological importance to the plant.
Haberlandt then "poisoned" the plant, by sprinkling it with a 0.1 per
cent sublimate solution of alcohol. The purpose of this experiment was
to ascertain whether in the secretion of water there was question of a
merely physical process or of a vital process. In the first case the
action of the hydathode should continue even after the treatment with
the sublimate solution, while in the latter case it should not. As the
secretion ceased the obvious conclusion to be deduced from this
experiment is that the hydathodes do not act as purely mechanical
filtration-apparatuses, as one might have thought, but that there is
here evidence of an active vital process in the plant; the unusual term
"poisoning" is therefore really justified under present circumstances.
Let me dwell for a moment on this result, for, although it may be
somewhat foreign to our present purpose and to the further observations
of Haberlandt, it is very significant in itself. The water moves in the
plant in closed cells, as the cells of the aqueous gland are entirely
closed, but the organic membrane, as every one knows, has the peculiar
physical property of allowing water to pass through, the pressure, of
course, being applied on the side of least resistance; when therefore
the water is forced into the cells by root-pressure, it is easily
intelligible that according to purely physical laws it should come to
the surface of the leaf on the side of the least resistance, that is,
by way of the water-crevices. Even the defenders of "vital force" would
not find any reason in this for not considering the phenomenon of
distillation in this case a purely physical phenomenon. And still
according to Haberlandt's experiments it is not. The sublimate could at
most only impede the process of filtration, but should under no
circumstances have destroyed it. But it does destroy it, and the
hydathode dies. The conclusion certainly follows from this that this
process is connected with some vital function. Even if the hydathode is
treated with sublimate solution, all the conditions for mechanical
filtration still remain: the earth has moisture which can be taken up
by the roots so that root-pressure still exists. The water is in all
cases conveyed to the hydathodes through the vascular fibres, the cell
walls of the hydathodes are still adapted for filtration, and yet they
do not filter. Hence some other factor must join itself to the
physico-mechanical process of filtration and affect or destroy it, and
this factor can be found only in the protoplasm, the vital element of
the cells; for we know that the sublimate acts with pernicious effect
on it and in such a manner that it destroys its entire power of
reaction; it kills it, as we say.
The experiment under discussion has, therefore, great significance for
our view of the vital processes in the plant; it proves beyond doubt
that these processes are in no way of a purely mechanical nature, but
that there is something underlying all this, a hitherto inexplicable
something, which we call "life." In all vital activities, physical and
chemical processes certainly do occur; they do not, however, take place
spontaneously but are made use of by the vital element of the plant to
produce an effect that is desirable or necessary for the vital activity
of the plant. If the vital element is dead, no matter how favorable the
conditions may be for chemical and physical processes, these do not
take place and the effect necessary for life is not obtained. It is
very remarkable after all that according to the experiment of
Haberlandt this peculiar relation should become apparent in a process
that is so open to our investigation as the filtration of water through
the cell-wall of a plant.
After what has been said I consider this simple experiment of
Haberlandt of great significance; for it is a direct proof of the
existence of a vital force. One may resist to his heart's content, but
without avail; vital force is again finding its way into science. More
and more cognizance is being taken of the fact that 60 and 70 years ago
people jumped at conclusions very imprudently when they believed that
the first artificial preparation of organic matter (urea, by Woehler)
had proven the non-existence of a vital force. Since then there has
been great rejoicing in the camp of materialists who scoffed at the
"ignorant" who would not as yet forsake vital force. "Behold," they
said, "in the chemist's retort the same matter is produced chemically
that is produced in the body of the animal, without the direction of a
hidden vital force, which, if it is not necessary in the one case,
neither is it necessary in the other." Any one who had given the matter
careful consideration could even at that time have known where the
"ignorant" really were. That in both cases chemical processes take
place is clear and undisputed, but the materialists forgot entirely
that even in the laboratory it was not the mere contact of the elements
that produced the urea; a chemist was needed and in this case not any
one arbitrarily chosen, but a man of the genius and knowledge of a
Woehler to watch over the process, and utilize and partly direct the
laws of chemistry in order to obtain the desired result. Hence it was
even then absurd to deny vital force as a consequence of that
experiment. Since, however, it was well-adapted for materialistic
purposes, this denial was proclaimed with the sound of trumpet
throughout the land, and repeated again and again with surprising
tenacity, with the result that even thoughtful investigators rejected
vital force almost universally in the seventies and eighties.
It has always been a problem to me how this could have happened. It
can, indeed, be explained only on the supposition that naturalists were
adverse to the introduction of anything into nature, that appeared to
them mystical and mysterious. Nor is such a procedure at all necessary:
vital force is by no means a mysterious, ghostly power that soars above
nature, but a force of nature like its other forces, as mysterious and
as definite as they are, only that it dominates a specified group of
beings, namely, living organisms. It may readily be compared with any
other natural phenomenon. For instance, the phenomenon of crystallization
has its well determined sphere of activity, viz., the mineral world. It
employs definite mathematico-physical laws to obtain a specified
result, and even acts differently in different mineral substances in so
far as it produces in the one case this, in the other case that form;
but still it should be a similarly directed force which has the effect
of producing these peculiar forms. Precisely similar is it with vital
force. It has its determined sphere of activity, the kingdom of living
organisms; it acts according to definite physico-chemical laws in
producing a specified result; it acts differently in different living
organisms; it is therefore a force of nature as clear yet as mysterious
as the force of crystallization or as any other force of nature. Hence
one has no cause to complain of its mysteriousness, for all other
forces of nature are just as much, or if you will, just as little
mysterious as vital force. The only thing to be maintained is this,
that living organisms are dominated by a special force with special
phenomena and special activities, even as in mineral substances there
is a special dominant force which produces special phenomena and
exercises special activities.
It is possible to produce crystals in the laboratory, but no one will
be so foolish as to maintain that in nature crystals are not formed in
consequence of a very definite force inherent in the mineral-substances;
nor will any one deny the existence of the force of crystallization
because it does not appear in living organisms.
Nor have I ever despaired of a return of the theory of vital force. A
change of opinion has really taken place during this decade; at present
the voices for a vital force are constantly growing stronger and it
will most probably not be very long before it will be again universally
recognized, not as something preternatural, of course, but as a force
of nature on an equal footing with the other forces of nature, with
activities, just as mysterious and just as well-attested as the
activities of the other forces of nature.
Haberlandt's experiment, however, had also an indirect consequence that
is of far-reaching importance. He observed that within a few days new
water-secreting organs of an entirely different structure and of
different origin were formed on the leaves that had been sprinkled with
sublimate. Over the bundles of vascular fibres, little knots as large
as a pin head arose in larger numbers out of a tissue underlying the
top layer; out of these the water now oozed every morning. Closer
investigation disclosed the fact that these organs develop only on
young immature leaves where groups of peculiar, perishable gland-hairs
are found; beneath these dead mucous glands the substitute secretive
organs originate in the inner tissue. It is of no importance to state
in what particular cells they originate.
Suffice it to say that they are colorless capillary tubes originating
in various cells; projecting like the hairs of a brush, containing
living protoplasm and evanescent chlorophyll. It is also important
to note that this new organ is immediately connected with the
water-conducting system consisting of bundles of vascular fibres.
Haberlandt furthermore indicates especially that these organs when
viewed in connection with the process of secretion give evidence of an
active vital principle as well as of simple mechanical filtration.
These substitute organs are all indeed well adapted to their purpose
and adequately replace the old secretive organs, but they so easily dry
out and are so little protected that after a week they become parched
and die because wound-cork forms under them. The leaf no longer
produces new hydathodes, but on its lower side it produces growths that
function as vesicles, by means of which it continues to sustain itself.
Haberlandt furthermore records a phenomenon perhaps analogous to this
on the grape-vine, but with this exception the case described by him is
unique. In order to pass any further judgment regarding it, we should
have to ascertain whether the whole phenomenon is not a case of
so-called adaptation; if so, processes should be found in nature,
analogous to the poisoning of the hydathodes in this experiment, which
result in the destruction of the hydathodes so that in consequence the
plant would have gained the power of making good the loss, by means of
the substitute organs. Such processes, however, (even through poisoning
or through parasites) would be very highly improbable. Equally
incredible is the alternative possibility that the new organs would be
produced by the plant not as a substitute but as a supplementary
apparatus when the old ones would not suffice for secretion in case of
very large absorption of water. This also must doubtlessly be rejected,
as Haberlandt has observed.
Powers of adaptation should, of course, according to Darwinism, be
gradually acquired in the struggle for existence, as in that case they
should also have stability; but since this is not possessed by the new
organs, the presumption is that they do not possess the character of
adaptation. They are therefore new organs that originated after an
entirely unnatural and unforeseen interference with the normal vital
functions and in consequence of a self-regulating activity of the
organism.
What then is there in the whole phenomenon worthy of notice with regard
to the theory of Descent?
1. An immediately well adapted new organ has here originated very
suddenly without any previous incipient formation, without gradual
perfection and without stages of transition.
2. In its formation struggle for existence and natural selection are
entirely excluded, neither can find any application whatever even
according to the newer exposition of Weismann. Haberlandt himself draws
this conclusion.
3. If this phenomenon of a suddenly appearing change can take place in
the course of the development of the individual, there can be no
obvious reason why it should not take place in the same manner (without
natural selection or struggle for existence) in the course of the
phylogenetic development.
It is manifestly of the greatest importance that in this case a direct,
experimental proof has been given that an organ has originated suddenly
and without the aid of Darwinian principles. Haberlandt's article is
nothing less than a complete renunciation of Darwinism on the part of
Haberlandt, a renunciation which we greet with great satisfaction.
In fact one such observation would really suffice to set aside
Darwinism and prove the utter insufficiency of its principles to give
explanation of the origin of natural species. On the other hand, this
observation plainly proves two things: first, that the above mentioned
doctrine of Koelliker, now held by Korschinsky is a move in the right
direction for the discovery of the causes of descent; and secondly,
that the principal cause of the evolution is not to be sought in
environment and blind forces but in the systematically working,
internal vital principle in plants and animals. With that, however, an
important part of the foundation of the mechanical-materialistic view
of the world is demolished.