MORPHOLOGY UNDER THE INFLUENCE OF THE DOCTRINE OF METAMORPHOSIS AND OF
THE SPIRAL THEORY.
1790-1850.
The efforts of Jussieu, De Candolle, and Robert Brown were directed to
the discovery of the relationship between different species of plants
by comparing them together; the doctrine of metamorphosis founded
by Goethe set itself from the first to bring to light the hidden
relationship between the different organs of one and the same plant.
As De Candolle’s doctrine of symmetry derived the different species
of plants from an ideal plan of symmetry or type, so the doctrine
of metamorphosis assumed an ideal fundamental organ, from which the
different leaf-forms in a plant could be derived. The stem came into
consideration only as carrying the leaves, the root was almost entirely
disregarded. As the resemblance of nearly allied species of plants
suggests itself naturally and unsought to the mind of the unbiassed
observer, so also does the connection between different organs of a
leafy nature in one and the same plant. Cesalpino called the corolla
simply a ‘folium’ (leaf); he and Malpighi regarded the cotyledons also
as leaves; Jung called attention to the variety of the leaf-forms,
which are found in many plants at different heights on the same stem;
Caspar Friedrich Wolff, the first who bestowed systematic consideration
on the subject, declared in 1766, that he saw nothing ultimately in
the plant but leaves and stem, including the root in the stem[42].
Long before Goethe’s time speculation had busied itself with attempts
to explain these observations; we saw how Cesalpino and Linnaeus,
starting from the old view that the pith is the seat of the soul in
plants, regarded the seeds as metamorphosed pith, the floral envelopes
with the stamens and the true leaves as metamorphosed layers of the
rind and wood of the stem. The word metamorphosis from their point
of view had a very plain meaning; it was really the cylindrical pith
whose upper end changed into seeds, it was the actual substance of the
cortex which produced both the ordinary leaves and the parts of the
flower. Wolff on the other hand from a point of view of his own gave
an apparently intelligible physical explanation of the proposition,
that all appendages of the stem are leaves, but the explanation had
the fault of not being true; he attributed the metamorphosis of leaves
to altered nourishment, the flowers especially to his ‘vegetatio
languescens.’
GOETHE’S conception of the matter was from the first much less
clear, and chiefly because he was never able to bring the abnormal
into its true connection with the normal or ascending metamorphosis.
In the first sentence of his ‘Doctrine of metamorphosis’ (1790) he
says, ‘that it is open to observation that certain exterior parts of
plants sometimes change and pass into the form of adjacent parts,
either wholly or in a greater or less degree.’ In the cases of
which Goethe is here thinking a distinct meaning can be affixed to
the word metamorphosis; if, for example, the seeds of a plant with
normal flowers produce a plant which has petals in place of stamens,
or in which the ovaries are resolved into green expanded leaves, it
is actually the case that a plant of a known form has given rise
to another plant of a different form, in other words, a change or
metamorphosis has really taken place. But we cannot reason in this
way in the case of that which Goethe calls normal or ascending
metamorphosis. When in a given species, which has remained constant
with all its marks for countless generations, the cotyledons, the
leaves, the bracts, and the parts of the flower are called leaves,
this must be merely the result of abstraction, which has led to the
generalising of the idea of a leaf; if we make abstraction of the
physiological characters of the carpels, stamens, floral envelopes,
and cotyledons, and regard only the way in which they originate on
the stem, we are justified in including them in one general idea
with ordinary leaves, and to this idea we quite arbitrarily give
the name leaf. But this does not justify us in speaking of a change
of these organs, so long as we consider the whole plant in question
as a hereditary and constant form. For the plant therefore taken as
constant the idea of metamorphosis has only a figurative meaning; the
abstraction performed by the mind is transferred to the object itself,
if we ascribe to it a metamorphosis which has really taken place only
in our conception. The case would be different, if here as well as in
the abnormal instances above-mentioned we could assume that the stamens
and other organs of the plants lying before us were ordinary leaves in
their progenitors. So long as this assumption of an actual change is
not even hypothetically made, the expression change or metamorphosis is
purely figurative, the metamorphosis is a mere ‘idea.’ This distinction
Goethe has not made; he did not clearly see that his normal ascending
metamorphosis can only have the meaning of a scientific fact, if a
real change is assumed to take place in the course of propagation
in this case, as in that of abnormal metamorphosis or misformation.
A comparison of his various expressions shows that he took the word
metamorphosis sometimes in its literal, sometimes in its ideal and
figurative sense; for instance, he says expressly, ‘We may say that
a stamen is a folded petal, just as we may say that a petal is a
stamen in a state of expansion.’ This sentence shows that Goethe did
not regard a particular leaf-form as first in time, and that others
proceeded from it by change; he uses the word metamorphosis in a purely
ideal sense. At other times his remarks may be interpreted as though
he really considered the normal ascending metamorphosis to be a real
change in the organs, arising from a transmutation of the species.
With this confusion of notion and thing, idea and reality, subjective
conception and objective existence, Goethe took up exactly the position
of the so-called nature-philosophy.
Goethe’s doctrine could only make its way to logical consistency and
clearness of thought by deciding for the one or the other way; he must
either assume that the different leaf-forms, which were regarded as
alike only in the idea, were really produced by change of a previous
form,—a conception that at once presupposes a change of species
in time; or he must entirely adopt the position of the idealistic
philosophy, in which idea and reality coincide. In this case the
assumption of a change in time was not necessary; the metamorphosis
remained an ideal one, a mere mode of view; the word leaf then
signifies only an ideal fundamental form from which the different forms
of leaves actually observed may be derived, as De Candolle’s constant
species from an ideal type.
If now we read Goethe’s further remarks on the doctrine of
metamorphosis attentively[43], we perceive that he really arrived at
neither of these conclusions, but perpetually vacillated between the
two; a number of his sayings might be collected, which might be taken
for precursors of a theory of descent, as they have been taken by some
modern writers; but it is quite as easy to make a selection which would
carry us back to the position of the ideal philosophy and the constancy
of species. In the later years of his life the idea of a physical
metamorphosis accomplished in time, and involving a change of species,
does appear more distinctly in Goethe’s writings. This explains
the lively, nay passionate, interest which he took in the dispute
between Cuvier and Geoffrey de St. Hilaire in 1830[44]. We gather from
it that Goethe, in spite of all his wanderings in the mists of the
nature-philosophy of the time, felt a growing need for some clearer
insight into the nature of metamorphosis, both in plants and animals,
without ever being able to make his way into the clear light.
But these better motions remained without importance for the history of
botany; the adherents of his doctrine of metamorphosis all apprehended
it in the sense of the nature-philosophy, and Goethe himself did
not remonstrate against the frightful way in which it was distorted
by them. Its further development therefore was in accordance with
the principles of that philosophy, which was accustomed to apply
the results of purely idealistic views in an uncritical way to
imperfectly observed facts. Above all the difficulty remained unsolved,
how the dogma of the constancy of species was to be brought into
logical connection with the idea of the metamorphosis of organs. The
supranatural, which Elias Fries found in the natural system, subsisted
still in the doctrine of metamorphosis in comparing the organs of a
plant.
Still more obscure and entirely the product of the nature-philosophy is
Goethe’s view of the spiral tendency in vegetation. At p. 194 of his
essay entitled ‘Spiraltendenz der Vegetation’ (1831) he says: ‘Having
fully grasped the idea of metamorphosis we next turn our attention to
the vertical tendency, in order to gain a nearer acquaintance with
the development of the plant. This tendency must be looked upon as an
immaterial staff, which supports the existence.... This principle of
life (!) manifests itself in the longitudinal fibres which we use as
flexible threads for many purposes; it is this which forms the wood in
trees, which keeps annual and biennial plants erect, and even produces
the extension from node to node in climbing and creeping plants. Next
we have to observe the spiral direction which winds round the other.’
This spiral direction which passes at once with Goethe into a ‘spiral
tendency,’ is seen in various phenomena of vegetation, as in spiral
vessels, in twining stems, and sometimes in the position of leaves.
The closing remarks of this short essay, in which he explains the
vertical tendency as the male, the spiral as the female principle in
the plant, show how far Goethe lost himself in the profundities of the
nature-philosophy. Thus he introduced his readers into the deepest
depths of mysticism.
It would be as useless as it would be wearisome to follow out in detail
to its extremest point of absurdity the progressive transformation
which the doctrine of metamorphosis underwent in the hands of the
botanists of the nature-philosophy school, and to see how its
catchwords, polarity, contraction and expansion, the stem-like and
the fistular, anaphytosis and life-nodes, and others, were compounded
with the results of the most every-day observation into meaningless
conglomerates; rough obscure impressions of the sense, as well as
incidental fancies, were regarded as ideas and principles. A full
account of these inconceivable aberrations is to be found in Wigand’s
‘Geschichte und Kritik der Metamorphose.’ Our own countrymen certainly,
Voigt, Kieser, Nees von Esenbeck, C. H. Schulz, and Ernst Meyer
(the historian of botany) bear off the palm of absurdity, but there
were others also, among them the Swedish botanist Agardh, and some
Frenchmen, Turpin, for instance, and Du Petit-Thouars[45], who were not
altogether free from this weakness. Even the best German botanists
of the time, such as Ludolph Treviranus, Link, G. W. Bischoff, and
others, managed to escape the influence of this philosophy of nature,
only where they confined themselves to the most barren empiricism.
Strange phenomenon! that as soon as gifted and understanding men began
to talk of the metamorphosis of plants, they fell into senseless
phrase-mongering; Ernst Meyer, for instance, was it is true no great
botanist, but he shows in his ‘Geschichte der Botanik’ that he
possessed a clever and cultivated intellect. The painful impression,
which the treatment of the doctrine of metamorphosis by these writers
makes upon us, is due partly to the fact that the deeper meaning
of the idealistic philosophy never attained to logical expression
in their hands, and still more to their indulgence in an unmeaning
play of phrases, combining the highest abstractions with the most
negligent and rudest empiricism, and sometimes with utterly incorrect
observations. Oken can claim the merit of more correct observation and
greater philosophical consistency, and if we reject his views, yet
his mode of presenting them has at least the pleasing appearance of
more consequential reasoning. We perceive for the first time the full
greatness of the debt which modern botany owes to men like Pyrame de
Candolle, Robert Brown, von Mohl, Schleiden, Nägeli, and Unger, the
latter of whom only slowly worked his way out of the trammels of the
nature-philosophy, when we compare the literature of the doctrine of
metamorphosis before the year 1840 with the present condition of our
science, for which they paved the way.
In spite of the real and apparent differences between Goethe’s
doctrine of metamorphosis and De Candolle’s doctrine of a plan of
symmetry, these writers agreed in this, that they set out alike from
the doctrine of the constancy of species, and led up equally to the
result, that alongside of manifold physiological differences in the
organs of plants certain points of formal agreement can be discovered,
which are expressed chiefly in the order of their succession and in
their relative positions. In this distinction lay the good kernel
of the doctrine of metamorphosis in Goethe, and Wolff, and even in
Linnaeus and Cesalpino: it was only necessary to set this free from
the dross with which the nature-philosophy had surrounded it, and
to make the relations of position in organs the subject of earnest
investigation, in order to secure important results in this branch
of morphology. The first step in this direction was taken by Carl
Friedrich Schimper, who was followed by Alexander Braun; both adopted
the main idea of the doctrine of metamorphosis in the form in which it
can be reconciled with the doctrine of constancy, that is, in a purely
idealistic sense. Both liberated themselves from the gross errors of
the nature-philosophers, and thus gave a more logical expression to the
purely idealistic morphological consideration of form in plants.
KARL FRIEDRICH SCHIMPER[46] founded before the year 1830 the theory
of the arrangement of leaves which is named after him, and which
he expounded to the naturalists assembled at Stuttgart in 1834 as
a complete and perfected system. Alexander Braun, in a review of
Schimper’s exposition in ‘Flora’ of 1835, gave a clear and simple
account of the theory, having already himself published an excellent
and comprehensive treatise on the same subject. The doctrine of
phyllotaxis appeared in these publications with a formal completeness
which could not fail to attract the attention of the botanical world
and indeed of a larger audience; and justly so, for, as unfortunately
so very seldom happens in botanical subjects, a scientific idea was in
this case not merely incidentally suggested, but was worked out in all
its consequences as a complete structure, and this structure gained in
external splendour from the circumstance that its propositions, dealing
with geometrical constructions, could be expressed in numbers and
formulae,—a thing hitherto unknown in botanical science.
That the leaves are arranged on the stems that produce them according
to fixed geometrical rules had been noticed by Cesalpino and by
Bonnet in the middle of the eighteenth century; but nothing more
resulted than weak attempts at mere description of different cases.
Schimper’s theory is marked by that which is at once its greatest
merit and its fundamental error, the referring of all relations of
position to a single principle. This principle lies in the idea
that growth in a stem has an upward direction in a spiral line, and
that the formation of leaves is a local exaggeration of this spiral
growth. The direction of the spiral line may change in the same
species, or in the same axis, and may even change from leaf to leaf.
The important variations in the arrangement of leaves are not shown
in their longitudinal distances, but in the measure of their lateral
deviations on the stem. The characteristic point in this theory is the
mode of considering these lateral deviations or divergences of the
leaves as they follow one another on an axis, the referring them to a
more general law of position. Means were at the same time skilfully
supplied for discovering the true conditions of arrangement, the
genetic spiral, in cases where the genetic succession of the leaves,
and consequently their divergence, could not be immediately recognised.
After innumerable observations, it appeared that there is a wonderful
variety in the disposition of leaves, but that at the same time a
comparatively small number of these variations commonly occur, and
that these ordinary divergences 1/2, 2/3, 3/8, 8/13, 13/21, etc. have
this remarkable relation to one another, that both the numerator and
denominator of each successive fraction are obtained by adding together
the numerators and denominators of the two preceding fractions, or
the individual fractions named are the successive convergents of a
continuous fraction:—
1
1 + 1
——-
1 + 1
——-
1....
By change of single cyphers in this, the simplest of all continuous
fractions, the expressions were also obtained for all measures of
position that deviate from the usual main series. The common occurrence
of so-called leaf-whorls seemed at once to be opposed to the principle
of special growth and to the doctrine of position founded upon it,
especially in the cases in which it was supposed that all the leaves
of a whorl arise simultaneously. But the founders of the doctrine,
relying on their geometrical constructions, declared that every
theory is incorrect, which sets out from the whorl as a simultaneous
formation. But the way in which the different leaf-whorls of a stem are
arranged among themselves, and are connected with continuous spiral
positions, required new geometrical constructions; it was necessary
to assume a supplementary relation (prosenthesis), which the measure
of the phyllotaxis adopts in the transition from the last leaf of
one cycle to the first of the next. Artificial as this construction
appears, it has the advantage of saving the spiral principle, and the
prosenthetic relation itself admits of being again expressed in highly
simple fractions,—a great advantage for the formal consideration of
the relative positions of the parts of the flower, and their relation
to the preceding positions of the leaves. The great skill shown by the
founders of the doctrine in the morphological consideration of the
whole plant-form appears equally in the establishment of the rules,
according to which the relations of position of the leaves of a
side-shoot connect with those of the mother-axis, and which made it
possible to represent the nature of inflorescences especially with
extreme clearness by means of geometrical figures. An expressive and
elegant terminology not only made the whole theory attractive, but
fitted it in a high degree to supply a suitable, plain, and precise
phraseology for describing the most varied forms of plants. That the
theory possesses such advantages as these may be gathered from the
fact, that since 1835 the morphological examination and comparison
not only of flowers and inflorescences, but also of vegetative shoots
and their ramification, has reached great formal completeness. A
thorough acquaintance with the principle of this doctrine has made it
possible to explain to reader or hearer the most intricate forms of
plants so clearly, that they may be said to reveal the law of their
formation themselves, and to grow before the eye of the observer,
while at the same time the most recondite relations of the organs of
the same or of different plants were brought out distinctly and in
elegant phraseology. When this mode of description was combined with
De Candolle’s views on abortion, degeneration, and adherence, and at
the same time took into consideration the chief physiological forms
of leaf-structures, according as these were developed as scales,
foliage-leaves, bracts, floral envelopes, staminal and carpellary
leaves, it was possible to give such an artistic account of every form
of plant, as made it visible to sense in its entirety, and at the same
time brought out the morphological law of its construction. Whoever
reads the writings of Alexander Braun and Wydler, and especially of
Thilo Irmisch (after 1873), who knew how to combine his descriptions in
a variety of ways with remarks on the biological relations of plants,
cannot fail to admire the extraordinary skill displayed by these men in
describing plants. Compared with the dry diagnoses of the systematists,
their descriptions attain to the dignity of an art, and present the
commonest forms to the reader in a new and attractive light. But the
theory had a further advantage; it seemed not only to present the form
of the plant in its matured state, but to treat it genetically; and
in fact it did possess an element of historical development, inasmuch
as it made the genetic succession of the leaves and of their axillary
shoots, which is at the same time the succession from the base to the
summit, the foundation of all consideration of the plant-form. But it
is also true that in this lay one of the weak sides of the theory; as
long as it was a question only of continuous spirals, the succession of
matured leaves does also represent the succession of their formation
in time; but this was not actually proved in the case of leaf-whorls,
and here, to save the theory, genetic relations had to be presupposed
for which no further proof was forthcoming, while fresh researches
have repeatedly shown that a strict application of Schimper’s theory
is found frequently to contradict the facts of development as directly
observed[47]. Moreover, regard was had only to those measurements
of divergence on the continuous genetic spiral which were taken on
the matured stem, while there was always the possibility that the
divergences might have been different at the first, and been afterwards
modified, as Nägeli subsequently suggested[48]. And again, the theory
had a dangerous adversary to encounter in the frequent occurrence
of leaves that are strictly alternate or crossed in pairs, and to
conceive of this as a spiral arrangement must at once appear to be
an arbitrary proceeding both from the mathematical point of view and
from that of historical development; the assumption of a return of the
genetic spiral from leaf to leaf, as for instance in the Grasses, like
the prosenthesis in the change of divergence, afforded, it is true, a
construction which was geometrically correct, but which could hardly
be made to agree with the history of development and the mechanical
forces concerned. Again, it was a great and essential defect in the
theory, that in assuming the spiral arrangement it entirely neglected
the relations of symmetry of the plant-form, which are in many cases
clearly expressed, and their connection with the outer world, on
which Hugo von Mohl had already published some excellent remarks in
1836,—a defect, which unhappily is not yet sufficiently appreciated. A
due consideration of these objections, and of the cases in which the
history of development is opposed to the constructions of the theory,
must have led to the conviction that the idea of a spiral tendency in
the growth of plants is at least not borne out in all cases, and more
profound reflexion would show, that a scientific principle, really
explaining the phenomena, is no more to be found in the assumption
of such a general tendency, than in a like assumption with regard to
the heavenly bodies, that they have a tendency to elliptic movement
because they commonly move in ellipses. Hence Hofmeister, the latest
investigator of the doctrine of phyllotaxis on the basis of the
history of development, comes to the conclusion that the notion of a
screw-shaped or spiral course of evolution of lateral members of plants
is not merely an unsuitable hypothesis, but an error. Its unreserved
abandonment is, he considers, the first condition for attaining an
insight into the proximate causes of the varieties of relative position
in the vegetable kingdom. But this judgment, correct as it is, was
pronounced thirty years after the appearance of Schimper’s theory;
history, which speaks from another point of view, and not only enquires
into the correctness of a theory but has to appraise its historical
importance, speaks in a less unfavourable manner. The chief point here
is not whether the theory was right, but how far it contributed to the
advance of the science. It was distinctly fruitful in results, for it
brought the important question of the relative positions of organs
for the first time into the front rank in the study of morphology; we
may even say that a large part of the results of the study of the
history of development were first brought into the true light by the
consistent application of the theory, or in the effort to disprove it.
With all its fundamental errors, Schimper’s theory remains one of the
most interesting phenomena in the history of morphology, because it was
carried out with thorough logical consistency. We should as little wish
to omit it from our literature, as modern astronomy would wish to see
the old theory of epicycles disappear from its history. Both theories
served to connect together the facts that were known in their time.
The fundamental error of the theory lies much deeper than appears at
first sight. Here too we have the idealistic conception of nature,
which refuses to know anything of the causal nexus, because it takes
organic forms for the ever-recurring copies of eternal ideas, and
in accordance with this platonic sphere of thought confounds the
abstractions of the mind with the objective existence of things. This
confusion shows itself in Schimper’s doctrine, inasmuch as he takes
the geometrical constructions, which he transfers to his plants and
which, though they may be highly suitable from his point of view, are
nevertheless purely arbitrary, for actual characters of the plants
themselves, in other words, takes the subjective connection of the
leaves by a spiral line for a tendency inherent in the nature of the
plant. Schimper in making his constructions overlooked the fact that,
because a circle can be described by turning a radius round one of its
extremities, it does not follow that circular surfaces in nature must
really have been formed in this way; in other words, he did not see
that the geometrical consideration of arrangements in space, useful as
it may otherwise be, gives no account of the causes to which they are
due. But this was not properly an oversight in Schimper’s case, for he
would have scarcely admitted efficient causes in the true scientific
sense into his explanations of the form of plants. How far Schimper
was from regarding plants as something coming into being in time and
according to natural laws, how profoundly he despised the principles of
modern natural science is shown in his judgment of Darwin’s theory of
descent and of the modern atomic theory, the coarseness of which is the
more surprising, because Schimper was a man of refined and even poetic
feeling. ‘Darwin’s doctrine of breeding,’ he says, ‘is, as I discovered
at once and could not help perceiving more and more after repeated and
careful perusal, the most shortsighted possible, most stupidly mean and
brutal, much more paltry even than that of the tesselated atoms with
which a modern buffoon and hired forger has tried to entertain us.’
Here is the old platonic view of nature flying at modern science; the
sternest ‘opposites’ that culture has ever produced.
The theory of Schimper, which should rather be called the theory of
Schimper and Braun, considering the active part which Braun took
from the first in framing and applying it, was capable of further
development only in the mathematical and formal direction, as was shown
especially in Naumann’s essay, ‘Ueber den Quincunx als Grundgesetz der
Blattstellung vieler Pflanzen’ (1845). The defects above described, but
not the merits of the theory were shared by the doctrine of phyllotaxis
laid down about ten years later by the brothers Louis and Auguste
Bravais. Their theory makes use of mathematical formulae to even a
greater extent than that of Schimper without paying any attention to
genetic conditions, and yet it is less consistent with itself, for it
assumes two thoroughly different kinds of phyllotaxis, the positions
in which are arranged in a straight and in a curved line; for the
latter without any apparent reason a purely ideal original divergence
is assumed which stands in irrational relation to the circumference of
the stem, and from it all other divergences should be derivable; and
this ultimately degenerates into mere playing with figures which in
this form afford no deeper insight into the causes of the relations of
position. As regards serviceableness in the methodic description of
plants the theory of the brothers Bravais is much inferior to that of
Schimper[49].
The genetic morphology founded about the year 1840 had to make the best
terms it could with the doctrine of phyllotaxis, which was constructed
on a totally different principle; the two went their way on the whole
side by side without disturbance from one another till the year 1868,
when Hofmeister in his general morphology attacked the principle
of Schimper’s theory, and endeavoured to substitute a genetic and
mechanical explanation of the relative positions for the purely formal
account of them; this attempt however, which from the nature of the
case has not yet led to a finished theory but nevertheless contains the
germ of a further development of this important doctrine, does not come
within the scope of this history.
The doctrine of phyllotaxis of Schimper and Braun, as it appeared
after 1830, had clearly presented only one side of the theory of
metamorphosis; what other elements there were in it capable of being
turned to speculative account were further cultivated by ALEXANDER
BRAUN between the years 1840 and 1860. In this period fresh points of
view were asserting themselves in botanical research; the founding of
the doctrine of cells, the study of the more delicate anatomy of plants
and of the history of development, and increased methodical knowledge
of the Cryptogams were enlarging the repertory of botanical facts,
while the physico-mechanical method of investigation was being more and
more adopted. Braun, who took an active part by his own researches in
this revolution in morphological botany, remained true nevertheless to
idealistic views; and in his frequent and comprehensive discussions of
the general results of the new investigations in accordance with these
views he has shown how far the idealistic platonising contemplation
of nature is in a condition to do justice to the results of exact
inductive enquiry. The opposition between his point of view and that
of the most eminent representatives of the inductive method became
more and more pronounced as years went on, and must be treated here
as a historical fact. But if the new tendency in botany pursued
especially by von Mohl, Schleiden, Nägeli, Unger, and Hofmeister may
be called inductive in the absence of a better term, and be contrasted
with the idealistic tendency represented by Braun and his school, it
must not be supposed that the latter did not equally contribute in
matters of detail to the enriching of the science by the method of
induction; on the contrary, Braun himself was the author of a series
of important works conceived in this spirit. When the new method is
here called inductive, it should be understood that the word is used
in a higher than the usual sense, and some explanation of this point
will not be superfluous in this place. Idealistic views of nature of
all times, whether they present themselves as Platonism, Aristotelian
logic, Scholasticism or modern Idealism, have all of them this in
common, that they regard the highest knowledge attainable by man
as something already won and established; the highest axioms, the
most comprehensive truths are supposed to be already known, and the
task of inductive enquiry is essentially that of verifying them; the
results of observation serve to elucidate already received views,
to illustrate already known truths; inductive enquiry has only to
establish individual facts. But in the sense in which inductive enquiry
was understood by Bacon, Locke, Hume, Kant, and Lange, its task is one
that goes essentially farther than this; it must not be content with
establishing individual facts, but it must employ them in the critical
examination of the most general notions that have come down to us,
and do its best to deduce new and comprehensive theories from them,
even where these may be entirely opposed to traditional views. But it
is part of the very nature of this method of investigation, that its
general results are subject to constant modification and improvement;
each more general truth has only a temporary value, and endures as
long as no new facts militate against it. The distinction therefore
between idealism and the inductive method in the domain of natural
science comes to this, that the former fits new facts into a scheme of
old conceptions, the latter deduces new conceptions from new facts;
the one is in its nature dogmatic and intolerant, the other eminently
critical; the one is conservative, the other always pressing forwards;
the one inclines to philosophic contemplation, the other to vigorous
and productive investigation. To this must be added one point of
great importance; the idealistic view of nature, rejecting causality,
explains nature from notions of design, and is teleological; ethical
and even theological elements are thus introduced into natural science.
It is in this form that the distinction between the idealistic view
represented by Braun and the modern inductive morphology presents
itself to us. If it were the task of this history only to record the
discovery of new facts, it would be superfluous to allude to these
differences here; but then it would also be impossible to estimate
rightly that portion of Braun’s long scientific labours which is at
once the most original and the most interesting from the historical
point of view, and which is to be found not so much in his many
descriptive and monographic works, as in his philosophic efforts in the
domain of morphology; these moreover deserve our consideration, because
they carry out Goethe’s half-explained conceptions to their remotest
consequences, and express in purer form the idealism which lies at the
foundation of the older nature-philosophy. No botanist since Cesalpino
has so thoroughly endeavoured to leaven the entire results of inductive
investigation with the principles of an idealistic philosophy, and to
explain them in its light.
Braun’s philosophical views not only accompany his knowledge of
facts, but everywhere permeate and colour it; in his writings,
contributions, and monographs on the most various subjects, facts
are regarded from the point of view of his philosophy. He has given
a general view of his philosophical principles and illustrated them
by a vast variety of facts in his famous book, ‘Betrachtungen über
die Erscheinung der Verjüngung in der Natur, insbesondere in der
Lebens-und Bildungsgeschichte der Pflanze’ (1849-50). He himself
directs attention to the opposition between his own stand-point and the
modern induction in the tenth page of the preface, where he replies to
the obvious objection, that his ideas may be regarded as antiquated,
in the words, ‘A more living contemplation of nature, such as is here
attempted, which seeks in natural bodies not merely the operation of
dead forces, but the expression of a living fact, does not lead, as
is supposed, to airy structures of fancy, for it does not pretend to
gain a knowledge of life in nature in any other way than as it is
revealed in phenomena,’ etc. This thought is still more distinctly
uttered in page 13 of the text; ‘As external nature without mankind
presents to us only the spectacle of a labyrinth without a guide,
so too scientific contemplation, which denies the inner spiritual
principle in nature and the intimate connection of nature with the
informing spirit[50], leads to a chaos of substances and forces, which
are unknown because divorced from spirit, or, to speak more precisely,
to a chaos of nothing but unknown causes, which work together in an
inexplicable manner.’ In a note to this passage he points expressly
to ‘the comfortless character of such an unreal mode of viewing
nature, which must necessarily endeavour to root out everything in
the conceptions and language of science which appears from its own
point of view to be anthropopathic,’ and he requires a tender, ethical
element as essential to botanical investigation. The chief object of
the volume is to prove that everything in organic life may be resolved
into rejuvenescence, of which idea no definition is actually given,
though the whole contents of the book are a search after a definition.
We may regard the idea of rejuvenescence, as presented by Braun, as an
extension of the idea of metamorphosis, in which extended form it is
adapted to take in even the results of the cell-theory, of the history
of development, and of the modern knowledge of the Cryptogams from the
idealistic point of view. One peculiarity of his mode of expounding
his views is observed here, as on other occasions, namely, that he
gives no precise and arbitrary definition to a word, for instance, like
rejuvenescence in the present place, and in a later work to the word
individual, but looks behind the word for a profound or even mysterious
meaning, which is to be perceived and brought to light by contemplation
of the phenomena. In page 5 he says, ‘Thus we see youth and age appear
alternately in one and the same history of development; we see youth
burst through age, and by growth or transformation step into the middle
of the development. This is the phenomenon of rejuvenescence, which is
repeated in endless multiplicity in every province of life, but nowhere
appears more clearly expressed or more accessible to investigation than
in the vegetable kingdom. Without rejuvenescence there is no history
of development.’—‘If then we ask for the causes of the phenomena of
rejuvenescence (page 7), we shall indeed allow that nature, into which
special life enters in its various manifestations, excites, awakes,
and works by the influences which the years and even the days bring
with them; but the true and inner cause can only be found in the
desire after perfection which belongs to every being in its kind, and
urges it to bring the outer world, which is strange to it, more and
more into complete subjection to itself, and to fashion itself in it
as independently as its specific nature admits.’ Further on he says
(page 17), ‘The impulse or tendency to development in each creature
is likewise no direction of activity impressed from without, but one
given from within and working as an inner determination and force
from the depth of the inner nature.’ A passage also from page 111 of
his treatise on polyembryony, published in 1860, may be quoted here;
‘Though the organism, in the process of realising itself, is subject
to physical conditions, yet the proper causes of its morphological and
biological characteristics do not lie in these conditions; its laws
belong to a higher stage of development of its being, to a sphere in
which the faculty of self-determination is distinctly manifested. If
this is so, the laws of an organic being appear as tasks imposed, the
fulfilling of which is not absolutely necessary but only in relation
to the attainment of a definite end, as precepts, to which strict
obedience may possibly not be paid.’ To return once more to the idea
of rejuvenescence, we find at page 18 the words, ‘As regards the idea
of rejuvenescence, from the foregoing considerations we draw the
conclusion, that the surrender of growths already accomplished and
the going back to new beginnings, the commencement of rejuvenescence,
indicate only the outer side of the proceeding, while the essential
part of it is an inner gathering up of forces, a new creating, as it
were, out of the individual principle of life, a fresh reflecting upon
the specific task or the gaining renewed hold upon the type which is
to be presented in the outer organism. By this means rejuvenescence
maintains its fixed relation to development, which can and ought to
present in gradually attained perfection that only which lies in the
nature of the creature, and is most intimately its own.’ And at the
conclusion of the work (page 347) he says, ‘The way in which the inner
spiritual nature of life is specially manifested in the phenomenon of
rejuvenescence may be defined as reminiscence in the true sense of
the word, as the power of grasping anew in the phenomenon the inner
destination of life as contrasted with its daily alienation and decay,
and applying it with renewed strength towards that which is without,’
etc.
This conception of rejuvenescence is, then, applied to all the
phenomena of life in plants; not only the metamorphosis of leaves, the
formation of shoots and their ramification, and the different modes of
cell-formation, but even palaeontological facts are manifestations of
rejuvenescence, which in the sequel puts off the form of an abstract
idea, and becomes personified into an active personality, as is seen in
page 8 in the expression, ‘activity of rejuvenescence.’
The relation of Braun’s views to the question of the constancy of
species may to some extent appear doubtful; some utterances of his may
be interpreted to admit a transmutation of species accomplished in
the course of ages, while others are opposed to this, and it is the
latter which appear to be consistent with the idealistic position. We
read, for instance, at page 9, ‘The appearance, as though the like was
always repeating itself in nature, is suggested when we glance back
from our station in time upon the succession of former epochs. Here
we find the real first beginnings of species and genera, and even of
orders and classes in the vegetable and animal kingdoms; we see at the
same time that more or less thorough transformations are connected
with the appearance of the higher grades in the organic kingdom, so
that genera and species of the old world disappear, and new ones step
into their place. All this change expresses not the mere accident of
convulsions, which, while they destroy, at the same time prepare new
ground for the prosperity of organic nature, but rather definite laws
whose action pervades all the individual detail of the development
of organic life.’ On the other hand we find at the conclusion of the
treatise on polyembryony, written a short time before the appearance
of Darwin’s memorable work, a sentence which makes the assumption of
a transmutation of species appear very doubtful; it says (page 257),
‘If we are justified in assuming a general organic connection in the
history of development in plant-forms, can we imagine that the type of
the Mosses and of the Ferns has come from the Algae, or _vice versa_,
that the Alga-form owes its origin to the Mosses and Ferns?’
The sentences here quoted to show Braun’s philosophical position
still give no idea of the way in which the principles embodied in
them influence the whole manner of presenting the facts in the
arrangement of his empirical material, but to give a clear idea of
this is impossible in so brief a notice as the present. His conception
of his subject is shown still more distinctly in a treatise which
appeared three years later, entitled ‘Das Individuum der Pflanze in
seinem Verhältniss zur Species, Generationsfolge, Generationswechsel
und Generationstheilung der Pflanze’ (1852-3). The definition of
the word individual is here sought, as that of rejuvenescence was
in the previous work,—a really difficult task, if we consider how
many meanings have been assigned to this word in the course of time;
in the individuals or atoms of Epicurus, the individuals or monads
of Leibnitz, the atoms of modern chemistry, the speculations of the
schoolmen on the ‘principium individuationis’ as opposed to the reality
which they assigned to universal conceptions, and in the customary
application of the word in every-day language, in which a man or a
single tree is called an individual, we have the general views of
various centuries, showing how the sense and meaning of old words
become changed, not unfrequently into their exact opposites. From
the nominalist position of modern natural science this is of little
importance, because this treats words and ideas as mere instruments
for mutual understanding, and seeks no meaning in either which has
not been previously and purposely assigned to them. Braun’s mode of
proceeding is quite different; by comparison of very various phenomena
of vegetation, and by examining former views on the subject of the
individual plant, he seeks to demonstrate a deeper meaning which must
be connected with the word.
Moreover, he makes the enquiry into the individual only a thread on
which to string his own reflections, in the course of which he once
more explains the principles of the teleological nature-philosophy,
and points out its opposition to modern science, the latter being
grievously misrepresented as materialistic, its atoms qualified as
dead, its forces as blind. It would scarcely be guessed from Braun’s
account that the history of philosophy could point to Bacon, Locke, and
Kant, as well as to Aristotle, that even the question of the individual
had been already handled by the schoolmen. A consideration of the
other point of view would have been all the more profitable, since the
author in the beginning of his treatise expresses the opinion that the
doctrine of the individual belongs to the elements of botany; it might
certainly be maintained that it is altogether superfluous.
His train of thought in search of that which must be called an
individual in the vegetable kingdom is briefly as follows: In forming a
conception of the plant-individual as the unity of a cycle of formation
or a morphological whole, our chief difficulty lies in the division
into parts and the divisibility (Getheiltheit und Theilbarkeit) which
are present in the very different stages of the organic structure of
plants. It is requisite therefore to find the middle way between the
morphological consideration of the individual plant which breaks up
the whole from above downwards, and the physiological which extends it
in the upward direction beyond all limits. Neither the leaf-bearing
shoots, though they are capable of developing into independent plants,
nor the parts of them, which have the same power, neither the single
cells, nor the granules they contain, and least of all the atoms of
dead matter which are the sport of blind forces, would answer to
the idea of the individual in plants. We have therefore to decide
which member of this many-graded series of potences in the cycle of
development subordinated to the species deserves by preference the name
of individual (p. 48). A compromise is then made; it is sufficient to
find a part of the plant which answers above all others to the idea
of the individual, for in this idea there must be two genetic forces,
multiplicity and unity. He then decides for the shoot or bud. ‘In
contemplating the plant-stem which is usually branched, especially
a tree with its many branches, mere instinctive feeling awakens the
suspicion that it is not a single being, a single life, to be classed
with the individual animal or individual man, but that it is a world
of united individuals which spring from one another in a succession of
generations,’ etc. He proceeds to show that this conception, arising as
it does from a sound, natural feeling, is also confirmed by scientific
examination. It appears, however, that many phenomena in the growth
of plants will not fall in well with this instinctive feeling, and
so he says at page 69, ‘We cut the Gordian knot in this way, that
if we have other and sufficient grounds for regarding branches as
individuals, we come to the determination to let every branch pass for
an individual, however strongly the appearance may be against it.’
The shoot is therefore the morphological individual in the plant, and
is analogous to the individual animal. It may certainly be objected,
that we may cut the knot in another way and maintain with Schleiden
that the cells are the individuals in the vegetable kingdom, if we do
not actually arrive by the same path at calling each atom, or at the
other end of the scale the whole self-nourishing plant, an individual,
for about equally strong reasons might be adduced for both one and the
other of these views. It all depends on the point of view we adopt in
such speculations, and on the weight we allow to instinctive feeling
in establishing scientific ideas. Braun declares very decidedly in
page 39 against the notion that the invisible ‘individua’ or atoms
of dead matter can be introduced into the consideration of the
plant-individual, as though the plant were a mere concrete of mutually
attracting and repelling atoms. If, he says, we will understand by the
term individual something absolutely indivisible, this is certainly the
last resort, but then we shall have no plant-individual. Moreover, no
eye has ever seen these atoms; their assumption is a mere hypothesis,
which we may confront with the other hypothesis of the continuity and
permeability of matter. The question therefore, he says, at page 39,
is whether we can speak of individuals in plants at all, and this
coincides with the other question, whether the plant is a mere product
of the activity of matter, and so an unsubstantial appearance in the
general circulation of nature, the offspring of blind agencies, or
whether it possesses a peculiar and independent existence. The views
of the physiologists, who reject the vital force and explain the
phenomena of life by physical and chemical laws, have robbed life of
its mysterious and most directly operative principle, and pulled down
the strong wall of separation between organic and inorganic nature.
‘Because physical forces appear to be everywhere confined to matter and
show in their operation a strict subjection to law, men have ventured
to regard the sum total of natural phenomena as the result of original
matter working in conjunction with definite powers according to the
laws of blind necessity, as a natural mechanism moving in endless
circulation.’ But he objects that the eternally necessary can only be
conceived of as accomplished from all eternity, and thus this physical
view would make all eventuality inconceivable. Further, the purpose of
the movement of nature must remain an insoluble enigma in this scheme
of blind necessity. ‘The inadequateness of the so-called physical view
of nature as compared with the teleological is therefore most felt in
the domain of organic nature, where special purpose in the phenomena
of life appears everywhere in greatest distinctness.’ The last remark
is indisputable so long as we maintain either the constancy of species
or a merely internal law of development; the solution of the enigma
was discovered a few years later in Darwin’s hypothesis, that all
adaptations of organisms are to be explained by the maintenance or
suppression of varieties, according as they are well or ill provided
with the means of sustaining the struggle for existence. No other
refutation or rather explanation of teleology in the science of organic
life has hitherto been attempted. It has been already pointed out that
systematic botany, by establishing the fact of affinity, saw itself
compelled at last to give up the constancy of specific forms in order
to make this fact intelligible, and here we see how the idea of the
adaptation of organisms is found to conflict with causality, unless
we assume that the forms which arise through variation only maintain
themselves, if they are sufficiently adapted to the surrounding
conditions.
The movement which began with Goethe and the nature-philosophy assumed
a clearer form, found its purest expression, and revealed its most
hidden treasures in the writings of Schimper and Alexander Braun; it
would be superfluous to submit to a detailed review the numerous works
of less important representatives of these views.
We turn from this realm of idealistic philosophy and imagination, from
rejuvenescence, the wave-pulse of metamorphosis, the spiral tendency
of growth, and the individuality of plants, to the last chapter of
our history of systematic botany and morphology, where there is less
dogmatism and less poetry, but a firmer ground on which will spring an
unexpected wealth of new discoveries and of deeper insight into the
nature of the vegetable world.