clear-sighted utterances on the nature and method of the natural system
to find him adopting the division into woody plants and herbs; nor is
the matter improved by his making the distinctive mark of trees and
shrubs to be the forming of buds, that is, distinct winter buds, which
is a mistake into the bargain. Yet we feel ourselves in some degree
compensated for this serious error by his dividing trees and herbs into
those with a two-leaved and those with a one-leaved or leafless embryo,
in modern language into Dicotyledons and Monocotyledons. Ray’s system
is undoubtedly the one which in the time preceding Linnaeus does most
justice to natural affinities. The following synopsis of his Classes
will serve to show the progress made since Cesalpino. The names in
brackets are the Linnaean names for some of the genera in particular
classes.
A. PLANTAE GEMMIS CARENTES (HERBAE).
(a) _Imperfectae._
I. Plantae submarinae (chiefly Polypes, Fucus).
II. Fungi.
III. Musci (Confervae, Mosses, Lycopods).
IV. Capillares (Ferns, Lemna, Equisetum).
(b) _Perfectae._
Dicotyledones (binis cotyledonibus).
V. Apetalae.
VI. Planipetalae lactescentes.
VII. Discoideae semine papposo.
VIII. Corymbiferae.
IX. Capitalae (vi-ix are Compositae).
X. Semine nudo solitario (Valerianeae, Mirabilis, Thesium, etc.).
XI. Umbelliferae.
XII. Stellatae.
XIII. Asperifoliae.
XIV. Verticillatae (Labiatae).
XV. Semine nudo polyspermo (Ranunculus, Rosa, Alisma!).
XVI. Pomiferae (Cucurbitaceae).
XVII. Bacciferae (Rubus, Smilax, Bryonia, Solanum, Menyanthes).
XVIII. Multisiliquae (Sedum, Helleboreae, Butomus, Asclepias).
XIX. Vasculiferae monopetalae (various).
XX. Vasculiferae dipetalae (various).
XXI. Tetrapetalae siliquosae (Cruciferae, Ruta, Monotropa).
XXII. Leguminosae.
XXIII. Pentapetalae vasculiferae enangiospermae (various).
Monocotyledones (singulis aut nullis cotyledonibus).
XXIV. Graminifoliae floriferae vasculo tricapsulari (Liliaceae,
Orchideae, Zingiberaceae).
XXV. Stamineae (Grasses).
XXVI. Anomalae incertae sedis.
B. PLANTAE GEMMIFERAE (ARBORES).
(a) _Monocotyledones._
XXVII. Arbores arundinaceae (Palms, Dracaena).
(b) _Dicotyledones._
XXVIII. Arbores fructu a flore remoto seu apetalae (Coniferae and
various others).
XXIX. Arbores fructu umbilicato (various).
XXX. Arbores fructu non umbilicato (various).
XXXI. Arbores fructu sicco (various).
XXXII. Arbores siliquosae (woody Papilionaceae).
XXXIII. Arbores anomalae (Ficus).
Of these classes only the Fungi, Capillares, Stellatae, Labiatae,
Pomiferae, Tetrapetalae, Siliquosae, Leguminosae, Floriferae, and
Stamineae can pass as wholly or approximately natural groups, and
there are mistakes even in these; moreover the majority of them had
long been recognised. The examples annexed in brackets show how open
the others are to objection. If it must be allowed on the one side
that Ray, like Jung, doubts whether the Cryptogams are propagated
without seeds, it is on the other side obvious that he makes as little
objection as his predecessors, contemporaries, and immediate successors
to the idea that Polypes and Sponges are vegetables. But worse than
this is the extremely faulty subordination and coordination in his
system; while the class of Mosses contains the Confervae, Lichens,
Liverworts, Mosses, and Clubmosses, and therefore objects as distinct
from one another as Infusoria, Worms, Crabs, and Mollusks, we find on
the contrary the one family of Compositae split up into four classes
founded on quite petty and unimportant differences. Finally, if Ray
recognised the general importance to the system of the leaf-formation
in the embryo, he was still far from strictly separating all
Monocotyledons and Dicotyledons.
Ray’s chief merit is that he to some extent recognised natural
affinities in their broader features; the systematic separation of the
smaller groups was but little advanced by him. He too, like Morison,
found two adherents in Germany in the persons of Christopher Knaut
(1638-1694), who published a flora of Halle in 1687 arranged after
Ray’s method, and Christian Schellhammer (1649-1716), professor at
Helmstädt and afterwards at Jena.
AUGUSTUS QUIRINUS BACHMANN (RIVINUS)[24] (1652-1725) was for Germany
what Morison and Ray were for England, and Tournefort for France.
From the year 1691 he was Professor of botany, physiology, materia
medica, and chemistry in Leipsic; he applied himself with such ardour
to astronomy that he injured his eyesight by observing spots in the
sun. With such a variety of occupations it is not surprising that his
special knowledge of plants was inconsiderable when compared with
that of the three just named; but he was better able than they to
appreciate the principles of morphology laid down by Jung, and to use
them for deciding questions of systematic botany. He did most service
by his severe strictures on the more prominent errors which botanists
up to his time had persisted in, his own positive contributions, at
least as far as the recognition of affinities is concerned, being
inconsiderable. His ‘Introductio universalis in rem herbariam,’ which
appeared in 1690, and contains 39 pages of the largest size, is the
most interesting for us; in it he declines the great quantity of
unnecessary work with which botanists occupied themselves, and declares
the scientific study of plants to be the only end and aim of botany.
He first treats of naming, and lays down with respect to generic and
specific names the principles which Linnaeus afterwards consistently
applied, whereas Bachmann himself did not follow his own precepts,
but injured his reputation as a botanist by a tasteless nomenclature.
Nevertheless he declared distinctly that the best plan is to designate
each plant by two words, one of which should be the name of the genus,
the other that of the species, and he ingeniously pointed out the great
convenience of this binary nomenclature in dealing with medicinal
plants, and in the writing of prescriptions. He refused to regard
cultivated varieties as species, though Tournefort and others continued
to do so.
In his system he rejected the division into trees, shrubs, and herbs,
showing by good examples that there is no real distinction of the kind
in nature. From many of his remarks in his critical dissertations
we might infer that he possessed a very fine feeling for natural
relationship, but at the same time expressions occur which seem to
show that he did not at all appreciate its importance in the system;
we notice this in Tournefort also. Because flowers come before the
fruit he jumps with curious logic to the conclusion that the main
divisions in the system should be derived from the flower, and in
following this rule he makes use of exactly that mark in the corolla
which has the least value for classification, namely, regularity or
irregularity of form. It is strange, moreover, that Bachmann, who spent
a considerable fortune on the production of copper-plate figures of
plants without any special object, though he founded his system on
the form of the flower, should yet have devoted only a superficial
study to its construction; his account of it is very inferior to that
of any one before or since his time. His classification thus founded
cannot be said to be an advance in systematic botany; nevertheless, he
had no lack of adherents, and among them in Germany, Heucher, Knaut,
Ruppius, Hebenstreit, and Ludwig; in England, Hill and others, who made
alterations here and there in his system, but any real development of
it was from its nature an impossibility; he endeavoured to defend it
against the assaults of Ray and Dillen; Rudbeck also declared against
him.
JOSEPH PITTON DE TOURNEFORT[25] (1656-1708) founded his system also
on the form of the corolla, but his views are to some extent opposed
to those of Bachmann. While the latter was pre-eminently critical and
deficient in knowledge of species, Tournefort was more inclined to
dogmatise, and atoned in the eyes of his contemporaries for want of
morphological insight by his extensive acquaintance with individual
plants. He is commonly regarded as the founder of genera in the
vegetable kingdom; but it has been already shown that the conceptions
of genera and species had been framed as early as the 16th century
from the describing of plants, and that Kaspar Bauhin also, in naming
his plants, consistently distinguished genera and species; moreover
Bachmann in 1690 had supported the claims of the binary nomenclature
as the most suitable for the designation of plants, though he did
not himself adopt it; Tournefort did adopt it, but in an entirely
different way from that of Bauhin. Bauhin gave only the name of the
genus, and supplied the species with characters; Tournefort, on the
other hand, provided his genera with names and characters, and added
the species and varieties without special description. Tournefort
therefore was not the first who established genera; he merely
transferred the centre of gravity, so to speak, in descriptive botany
to the definition of the genera; but in doing so he committed the great
fault of treating specific differences within the genus as a matter
of secondary importance. How little depth there was in his botanical
ideas may be seen not only from his very poor theory of the flower,
the imperfections in which, as in the case of Bachmann, are the more
remarkable, since he founded his system on the outward form of the
flower, but still more from the expression which he uses at the end of
his history of botany, a work otherwise of considerable merit; he says
there that the science of botany has been so far advanced since the
age of Hippocrates, that hardly anything is still wanting except an
exact establishing of genera. His general propositions on the subject
of systematic botany, together with much that is good, but which is
generally not new and is better expressed in the works of Morison, Ray,
and Bachmann, contain strange misconceptions; for instance, he classes
plants which have no flower and fruit with those in which these parts
are to be seen only with the microscope, that is, the smallness of
the organs is equivalent to their absence. It may seem strange that
his theory of the flower should be so imperfect, when the excellent
investigations of Malpighi and Grew into the structure of flowers,
fruit, and seed were already before the world (1700), and Rudolph Jacob
Camerarius had made known his discovery of sexuality in the vegetable
kingdom. This doctrine, however, Tournefort expressly refused to admit.
But the reproach of neglecting the labours of Malpighi and Grew is
equally applicable to Bachmann and the systematists up to A. L. de
Jussieu; we have here only the first example of the fact since so often
confirmed, that professed systematists shrank with a certain timidity
from the results of more delicate morphological research, and rested
their classifications as far as possible on obvious external features
in plants,—a proceeding which more than anything else delayed the
construction of the natural system.
Tournefort’s system is thoroughly artificial, if possible, more
artificial than that of Bachmann, and certainly inferior to Ray’s.
If we meet with single groups that are really natural, it is simply
because in some families the genera so agree together in all their
marks, that they necessarily remain united, whatever mark we select for
the systematic purpose. We do not find in Tournefort the distinction
between Phanerogams and Cryptogams already established by Ray, nor
the division of woody plants and herbs into Monocotyledons and
Dicotyledons; if his chief work, to which we confine ourselves here,
the ‘Institutiones rei herbariae,’ did not bear the date of 1700, we
might conclude that it was written before the ‘Historia Plantarum’
of Ray, and the chief work of Bachmann. Yet it has one merit of a
purely formal kind; it is pervaded by a rigorous spirit of system;
every class is divided into sections, these into genera, and these
again into species; figures of the leaves and of the parts of the
flower, very beautifully engraved on copper-plate and filling a whole
volume, are perspicuously arranged; the whole work therefore is easy
to consult and understand. But to form an idea of the confusion as
regards natural affinities that reigns in his system, we need only
examine the first three sections of his first class, when we shall find
Atropa and Mandragora together in the first section, Polygonatum and
Ruscus in the second, Cerinthe, Gentiana, Soldanella, Euphorbia, and
Oxalis in the third. The handiness of the book, the little interest
taken by most of the botanists of the time in the question of natural
relationship, and the continually increasing eagerness for a knowledge
of individual plants, are evidently the reasons why Tournefort gained
over to his side most of the botanists not only of France, but also
of England, Italy, and Germany; and why later attempts in systematic
botany during the first thirty or forty years of the 18th century were
almost exclusively founded on his system, as they were afterwards on
the sexual system of Linnaeus. Boerhaave, among others, proposed a
system in 1710, which may be regarded as a combination of those of
Ray, Hermann, and Tournefort, but it met with no support on any other
grounds.
We here take our leave of the systematists of the 17th century, and,
passing over the mere plant-collectors of the first thirty years of the
18th, turn at once to Linnaeus.
CARL LINNAEUS[26], called Carl von Linné after 1757, was born in 1707
at Rashult in Sweden, where his father was preacher. He began the study
of theology, but was soon drawn away from it by his preference for
botany, and in this pursuit he was encouraged by Dr. Rothmann, who sent
him to the works of Tournefort. In Lund, where he now studied medicine,
he became acquainted with Vaillant’s treatise, ‘De sexu plantarum,’ and
had his attention drawn by it to the sexual organs. In 1730, when he
was only twenty-three years old, the aged Professor Rudbeck gave up to
him his botanical lectures and the management of the botanic gardens,
and here Linnaeus began the composition of the ‘Bibliotheca Botanica,’
the ‘Classes Plantarum,’ and the ‘Genera Plantarum.’ In the year 1732
he made a botanical journey to Lapland, and in 1734 to Dalecarlia; in
1735 he went to Holland, where he obtained a degree; in that country
he remained three years, and printed the works above-named, together
with the ‘Systema Naturae,’ the ‘Fundamenta Botanica,’ and other
treatises. From Holland he visited England and France. In the year 1738
he returned to Stockholm and was compelled to gain a livelihood as a
physician, till in 1741 he became Professor of Botany in Upsala, where
he died in the year 1778.
Linnaeus is commonly regarded as the reformer of the natural sciences
which are distinguished by the term descriptive, and it is usual to say
that a new epoch in the history of our science begins with him, as a
new astronomy began with Copernicus, and new physics with Galileo. This
conception of Linnaeus’ historical position, as far at least as his
chief subject, botany, is concerned, can only be entertained by one who
is not acquainted with the works of Cesalpino, Jung, Ray, and Bachmann,
or who disregards the numerous quotations from them in Linnaeus’
theoretical writings. On the contrary, Linnaeus is pre-eminently the
last link in the chain of development represented by the above-named
writers; the field of view and the ideas of Linnaeus are substantially
the same as theirs; he shares with them in the fundamental errors of
the time, and indeed essentially contributed to transmit them to the
19th century. But to maintain that Linnaeus marks not the beginning
of a new epoch, but the conclusion of an old one, does not at all
imply that his labours had no influence upon the time that followed
him. Linnaeus stands in the same relation to the systematists of the
period we are considering that Kaspar Bauhin does to the botanists
of the 16th century; as Bauhin gathered up all that was serviceable
in his predecessors, Cesalpino only excepted, while the botanists of
our second period drew again from him, though they set out from other
points of view than his; so Linnaeus adopted all that the systematists
of the 17th century had built upon the foundation of Cesalpino’s ideas,
gave it unity and fashioned it into a system without introducing into
it anything that was fundamentally and essentially new; all that had
been developed in systematic botany from Cesalpino to Tournefort
culminated in him, and the results, which he put together in a very
original form and with the power of a master, were no more unfruitful
for the further development of botany than the contents of Kaspar
Bauhin’s works for the successors of Cesalpino.
Whoever carefully compares the works of Cesalpino, Jung, Morison, Ray,
Bachmann, and Tournefort with Linnaeus, ‘Fundamenta Botanica’ (1736),
his ‘Classes Plantarum’ (1738), and his ‘Philosophia Botanica’ (1751),
must be thoroughly convinced that the ideas on which his theories
are based are to be found scattered up and down in the works of his
predecessors; further, whoever has traced the history of the sexual
theory from the time of Camerarius (1694), must allow that Linnaeus
added nothing new to it, though he contributed essentially to its
recognition, and that even after Koelreuter’s labours he continued to
entertain some highly obscure and even mystical notions on the subject.
But that which gave Linnaeus so overwhelming an importance for his own
time was the skilful way in which he gathered up all that had been done
before him; this fusing together of the scattered acquisitions of the
past is the great and characteristic merit of Linnaeus.
Cesalpino was the first who introduced Aristotelian modes of thought
into botany; his system was intended to be a natural one, but it was
in reality extremely unnatural; Linnaeus, in whose works the profound
impression which he had received from Cesalpino is everywhere to be
traced, retained all that was important in his predecessor’s views, but
perceived at the same time what no one before him had perceived, that
the method pursued by Cesalpino, Morison, Ray, Tournefort, and Bachmann
could never do justice to those natural affinities which it was their
object to discover, and that in this way only an artificial though very
serviceable arrangement could be attained, while the exhibition of
natural affinities must be sought by other means.
As regards the terminology of the parts of plants, which was all that
the morphology of the day attempted, Linnaeus simply adopted all that
was contained in the Isagoge of Jung, but gave it a more perspicuous
form, and advanced the theory of the flower by accepting without
hesitation the sexual importance of the stamens, which was still but
little attended to; he thus arrived at a better general conception of
the flower, and this bore fruit again in a terminology which is as
clear as it is convenient; the terms monoecious, dioecious, triandrous,
monogynous, etc., still used in the science, and the later-invented
expressions dichogamous, protandrous, protogynous, etc., owe their
origin to this correct conception of the sexual relations in plants.
But there was one great misconception in the matter, which has not a
little contributed to increase Linnaeus’ reputation. He called his
artificial system, founded on the number, union, and grouping of the
stamens and carpels, the sexual system of plants, because he rested
its supposed superiority on the fact, that it was founded upon organs
the function of which lays claim to the very highest importance. But
it is obvious that the sexual system of Linnaeus would have the same
value for the purposes of classification, if the stamens had nothing
whatever to do with propagation, or if their sexual significance were
quite unknown. For it is exactly those characters of the stamens which
Linnaeus employs for purposes of classification, their number and mode
of union, which are matter of entire indifference as regards the sexual
function.
But though the notion that this artificial system has any important
connection with the doctrine of the sexuality of plants is evidently
due to a confusion of ideas, yet the progress of the science has shown,
that Linnaeus’ sexual system did often and necessarily lead to the
establishing of natural groups for the very reason, that the characters
of the stamens which he employed are entirely independent of their
function; for we must regard it as an important result of the labours
of systematists, that those characters of organisms are shown to be of
the greatest value for classification, which are entirely or in a very
great measure independent of the functions of the organs. The error,
which led Cesalpino to make the functional importance of the parts of
fructification the principle of his division, reappears therefore in
Linnaeus in another form; to find a principle of division, he turns to
those organs, whose function appears to him the most important, but he
takes his characters not from differences of function, but from the
number and mode of union, which are of no importance for the sexual
function. We meet with this error in Leibnitz and Burckhard, who are
mentioned here merely to defend Linnaeus from the charge repeatedly
brought against him by his contemporaries that he was indebted to these
two writers for the idea of his sexual system. They erroneously found
in the great physiological importance of the sexual organs a reason
for deriving from their differences the principles of division that
were to found a system; this error in theory Linnaeus shared with them,
but they did not correct it in practice, as Linnaeus did, by confining
himself to purely morphological features in working out his system.
What the renowned philosopher[27] incidentally uttered in the year 1701
on the matter in question is moreover so unimportant and so indistinct,
that Linnaeus could not gain much from it; what Burckhard[28] says
on the subject in his often-quoted letter to Leibnitz (1702) is
indeed much better, and comes near to Linnaeus’ idea; but it is a
very long way from the hints there given to the completion of the
well-articulated and highly practical system which Linnaeus constructed.
The botanists of the 16th century, and in the main even Morison
and Ray, had in one-sided fashion devoted their chief attention to
distinguishing species, Bachmann and Tournefort to the establishment
of generic characters, while they neglected species; Linnaeus, on the
contrary, applied equal care and much greater skill to describing both
genera and species. He reduced to practical shape the suggestion which
Bachmann had left to his successors, and so must be regarded, if not as
the inventor, at least as the real founder of the binary nomenclature
of organisms.
It is only fulfilling the duty of a historian to state the sources
from which Linnaeus drew, but it would be a misapprehension to see
in this any depreciation of a great man; it were to be desired that
all naturalists would, like Linnaeus, adopt all that is good in the
contributions of their predecessors, and improve or adapt it as
he did. Linnaeus himself has repeatedly quoted the sources of his
knowledge as far as they were known to him, and has in many cases
estimated the services of his predecessors with a candour which never
betrays a trace of jealousy, but often displays a warm respect, as
may be seen especially in the short introductions to the several
systems given in the ‘Classes Plantarum.’ Linnaeus could not only
recognise what was good in his predecessors and occasionally make
use of it, but he imparted life and fruitfulness to the thoughts of
others by applying them as he applied his own thoughts, and bringing
out whatever theoretical value they possessed. It was evidently this
freshness of life that often misled his successors into believing that
Linnaeus thought out and discovered everything for himself. We learn
to appreciate the contributions of Cesalpino and his successors in the
17th century, and even of Kaspar Bauhin for the first time in the works
of Linnaeus; we are astonished to see the long-known thoughts of these
writers, which in their own place look unimportant and incomplete,
fashioned by Linnaeus into a living whole; thus he was at once and in
the best sense both receptive and productive, and he might perhaps have
done more for the theory of the science if he had not been entangled
in one grave error, which was more sharply pronounced in him than in
his predecessors and contemporaries, that, namely, of supposing that
the highest and only worthy task of a botanist is to know all species
of the vegetable kingdom exactly by name. Linnaeus distinctly declared
that this was his view, and his school in Germany and England adhered
to it so firmly that it established itself with the general public, who
to the present day consider it as a self-evident proposition that a
botanist exists essentially for the purpose of at once designating any
and every plant by a name. Like his predecessors, Linnaeus regarded
morphology and general theoretical botany only as means to be used for
discovering the principles of terminology and definition, with a view
to the improvement of the art of describing plants.
We have hitherto spoken chiefly of the manner in which Linnaeus dealt
with his subject in matters of detail; in his inner nature he was a
schoolman, and that in a higher degree than even Cesalpino himself,
who should rather be called an Aristotelian in the strict sense of
the word. But to say that Linnaeus’ mode of thought is thoroughly
scholastic is virtually saying that he was not an investigator of
nature in the modern meaning of the word; we might point to the fact
that Linnaeus never made a single important discovery throwing light on
the nature of the vegetable world; but that would still not prove that
he was a schoolman.
True investigation of nature consists not only in deducing rules from
exact and comparative observation of the phenomena of nature, but
in discovering the genetic forces from which the causal connexion,
cause and effect may be derived. In the pursuit of these objects,
it is compelled to be constantly correcting existing conceptions
and theories, producing new conceptions and new theories, and thus
adjusting our own ideas more and more to the nature of things. The
understanding does not prescribe to the objects, but the objects to
the understanding. The Aristotelian philosophy and its medieval form,
scholasticism, proceeds in exactly the contrary way; it is not properly
concerned with acquiring new conceptions and new theories by means of
investigation, for conceptions and theories have been once for all
established; experience must conform itself to the ready-made system of
thought; whatever does not so conform must be dialectically twisted and
explained till it apparently fits in with the whole. From this point
of view the intellectual task consists essentially in this twisting
and turning of facts, for the general idea of the whole is already
made and needs not to be altered. Experience in the higher sense of
investigation of nature is rendered impossible by the fact, that we
are supposed to know all the ultimate principles of things; but these
ultimate principles of scholasticism are at bottom only words with
extremely indefinite meaning, abstractions obtained by a series of
jumps from every-day experience, which has not been tried and refined
in the crucible of science, and is therefore worthless; and the higher
the abstraction is raised, the farther it withdraws from the guiding
hand of experience, the more venerable and more important do these
‘abstracta’ appear, and we can finally come to a mutual understanding
about them, though again only through figures and metaphors[29].
Science, according to the scholastic method, is a playing with abstract
conceptions; the best player is he who can so combine them together,
that the real contradictions are skilfully concealed. On the contrary,
the object of true investigation, whether in philosophy or in natural
science, is to make unsparing discovery of existing contradictions and
to question the facts until our conceptions are cleared up, and if
necessary the whole theory and general view is replaced by a better.
In the Aristotelian philosophy and in scholasticism facts are merely
examples for the illustration of fixed abstract conceptions, but in the
real investigation of nature they are the fruitful soil from which new
conceptions, new combinations of thought, new theories, and general
views spring and grow. The most pernicious feature in scholasticism
and the Aristotelian philosophy is the confounding of mere conceptions
and words with the objective reality of the things denoted by them;
men took a special pleasure in deducing the nature of things from the
original meaning of the words, and even the question of the existence
or non-existence of a thing was answered from the idea of it. This
way of thinking is found everywhere in Linnaeus, not only where he
is busy as systematist and describer, but where he wishes to give
information on the nature of plants and the phenomena of their life,
as in his ‘Fundamenta,’ his ‘Philosophia Botanica,’ and especially in
his ‘Amoenitates Academicae.’ From among many instances we may select
his mode of proving sexuality in plants. Linnaeus knew and lauded the
services rendered to botany by Rudolph Jacob Camerarius, who as a
genuine investigator of nature had demonstrated the sexuality of plants
in the only possible way, namely, that of experiment. But Linnaeus
cares little for this experimental proof; he just notices it in
passing, and expends all his art on a genuine scholastic demonstration
intended to prove the existence of sexuality as arising necessarily
from the nature of the plant. He connects his demonstration with the
dictum ‘omne vivum ex ovo,’ which Harvey had founded on an imperfect
induction, and which he evidently takes for an _a priori_ principle,
and concludes from it that plants also must proceed from an ‘ovum,’
overlooking the fact that in ‘omne vivum ex ovo’ plants already form
a half of the ‘omne vivum’; then he continues, ‘reason and experience
teach us that plants proceed from an ‘ovum,’ and the cotyledons
confirm it’; reason, experience, and cotyledons! Surely a remarkable
assemblage of proofs. In the next sentence he confines himself at first
to the cotyledons, which according to him spring in animals from the
yolk of the egg, in which the life-point is found; consequently, he
says, the seed-leaves of plants, which envelope the ‘corculum,’ are
the same thing; but that the progeny is formed not simply from the
‘ovum,’ nor from the fertilising matter in the male organs, but from
the two combined, is shown by animals, hybrids, reason, and anatomy. By
reason in this and the previous sentence he understands the necessity,
concluded from the nature, that is, the conception of the thing, that
it must be so; animals supply him with the analogy, and anatomy can
prove nothing, as long as it is not known what is the design of the
anatomical arrangements. But the weakest side of this proof lies in the
hybrids, for Linnaeus, when he wrote the ‘Fundamenta,’ knew of none
except the mule; hybrids in plants were first described by Koelreuter
in 1761, and these Linnaeus nowhere mentions; and what amount of proof
can be drawn from the vegetable hybrids, which Linnaeus afterwards
supposed himself to have observed, but which were no hybrids, we
shall see in the history of the sexual theory; here we need only
remark that he arrives at the existence of these hybrids from the
idea of sexuality exactly as he arrived at that of sexuality from the
idea of hybridisation. Then he goes on with his demonstration; ‘that
an egg germinates without fecundation is denied by experience, and
this must hold good therefore of the eggs[30] of plants—every plant
is provided with flower and fruit, even where these are not visible
to the eye’; with Linnaeus, of course, this is logically concluded
from the conception of the plant or of the ‘ovum’; he alleges indeed
certain observations as well, but they are incorrect. He continues,
‘The fructification consists of the sexual organs of the flowers; that
the anthers are the male organs, the pollen the fertilising matter, is
proved by their nature, further by the fact that the flower precedes
the fruit, as also by their position, the time, the loculaments
(anthers), by castration, and by the structure of the pollen.’ Here too
the main point with Linnaeus is the nature of the male organs, and that
we may know what this nature is he refers to a former paragraph, where
we learn that the essence of the flower is in the anthers and stigma.
Almost all his demonstrations consist of such reasonings in a circle
and in arguing from the thing to be proved. And while the passages
quoted show how much he did for the doctrine of sexuality, we find
this sophistical style of reasoning still more copiously displayed in
the essay entitled ‘Sponsalia Plantarum’ in the ‘Amoenitates’ (i. p.
77), and in a worse form still in the essay, ‘Plantae Hybridae’ (Amoen.
iii. p. 29). That Linnaeus had not the remotest conception of the way
in which the truth of a hypothetical fact is proved on the principles
of strict inductive investigation is shown by these and many other
examples, and by his enquiry into the seeds of mosses (Amoen. ii. p.
266), upon which he prided himself not a little, but which is really
inconceivably bad even for that time (1750). It was not Linnaeus’ habit
to occupy himself with what we should call an enquiry; whatever escaped
the first critical glance he left quietly alone; it did not occur to
him to examine into the causes of the phenomena that interested him; he
classified them and had done with them; as for instance in his ‘Somnus
Plantarum,’ as he called the periodical movements of plants. We cannot
read much of the ‘Philosophia Botanica’ or the ‘Amoenitates’ without
feeling that we are transported into the literature of the middle ages
by the kind of scholastic sophistry which is all that his argumentation
amounts to; and yet these works of Linnaeus date from the middle of
the last century, from a time when Malpighi, Grew, Camerarius, and
Hales had already carried out their model investigations, and his
contemporaries Duhamel, Koelreuter, and others were experimenting in
true scientific manner. This peculiarity in Linnaeus explains why
men like Buffon, Albert Haller, and Koelreuter treated him with a
certain contempt; and also why his strict adherents in Germany, who
lived on his writings and were unable to separate what was really
good in him from his mode of reasoning, came to make their own botany
like anything rather than a science of nature. Linnaeus was in fact a
dangerous guide for weak minds, for his curious logic, among the worst
to be met with in the scholastic writers, was combined with the most
brilliant powers of description; the enormous extent of his knowledge
of particulars, and above all the pre-eminent firmness and certainty
which distinguished his mode of dealing with systematic botany, could
not fail to make the profoundest impression on those who judged of
the powers of an investigator of nature by these qualities alone. One
of his greatest gifts was without doubt the power which he possessed
of framing precise and striking descriptions of species and genera in
the animal and vegetable kingdoms by means of a few marks contained in
the smallest possible number of words; in this point he was a model of
unrivalled excellence to all succeeding botanists.
On the whole the superiority of Linnaeus lay in his natural gift for
discriminating and classifying the objects which engaged his attention;
he might almost be said to have been a classifying, co-ordinating,
and subordinating machine. He dealt with everything about which he
wrote in the way in which he dealt with objects of natural history.
The systematic botanists whom he mentions in the ‘Classes Plantarum’
are classified then and there as fructists, corollists, and calycists.
All who occupy themselves in any way with botany are divided into two
great classes, the true botanists and mere botanophils, and it is
very characteristic of his way of thinking that he places anatomists,
gardeners, and physicians in the latter class. True botanists again
are either mere collectors or systematists. To the collectors
belong all who add to the number of known plants, also authors
of monographs and floras, and the botanical explorers of foreign
countries, whom we should now more courteously call systematists. By
systematists Linnaeus understands those who occupy themselves with
the classification and naming of plants, and he divides them into
philosophers, systematists proper, and nomenclators; the philosophers
are those who study the theory of the science on principles founded on
reason and observation, and are subdivided into orators, institutors,
erystics, and physiologists; the latter are those who discovered the
mystery of sexuality in plants, and hence Malpighi, Hales, and such
men are not physiologists in Linnaeus’ sense. The second class of
systematists, the systematists proper, he distinguishes into orthodox
and heterodox, the former taking the grounds of division exclusively
from the organs of fructification, while the latter use other marks
as well. In this manner Linnaeus treats every subject of which he has
to speak, and wherever he can in short, numbered sentences, which
look like descriptions of genera and species. His mind and character
were fully formed in 1736 when he wrote his ‘Fundamenta,’ and he
preserved his peculiarities of style from that time forward; we find
the same modes of expression in the ‘Nemesis Divina,’ a treatise on
religion and morals addressed as a legacy to his son. Where these
peculiarities of manner and expression are suitable they make a
favourable impression on the reader, as for instance in the short
accounts he gives of the various systems in the ‘Classes Plantarum,’
a work in which Linnaeus was quite in his element; there he traces
with a fine instinct the guiding principles of each system, pronounces
upon its merits and defects, and sets it before the reader in numbered
sentences of epigrammatic brevity. This manner is strictly adhered to
in the ‘Philosophia’ also, and it has certainly helped not a little
to withdraw the attention of his reader from his many fallacies in
argument, especially his oft-recurring reasonings in a circle.
This remarkable combination of an unscientific philosophy with mastery
over the classification of things and conceptions, this mixture of
consistency in carrying out his scholastic principles with gross
inaccuracies of thought, impart to his style an originality, which is
rendered still more striking by the native freshness and directness,
and not unfrequently by the poetic feeling, which animate his periods.
In any attempt to estimate the advance which the science owes to the
labours of Linnaeus, the chief prominence must be assigned to two
points; first to his success in carrying out the binary nomenclature in
connection with the careful and methodical study which he bestowed on
the distinguishing of genera and species; this system of nomenclature
he endeavoured to extend to the whole of the then known vegetable
world, and thus descriptive botany in its narrower sense assumed
through his instrumentality an entirely new form, which, serving as
a model for the naming and defining of the larger groups, could be
applied without modification to the founding and completing the natural
system. When at a later time Jussieu and De Candolle marked out their
families and groups of families, their mode of proceeding was in the
main that of Linnaeus when distinguishing his genera by abstraction of
specific differences. This merit has been always assigned to Linnaeus
without reserve. The second merit has been less recognised, and yet it
is at least of equal importance; it is that of having first perceived
that the attempt made by Cesalpino and his successors to found a
system, that shall do justice to natural affinities, on predetermined
marks can never succeed. Linnaeus framed his artificial sexual system,
but he exhibited a fragment of a natural system by its side, while he
repeatedly declared that the chief task of botanists is to discover
the natural system. Thus he cleared the ground for systematic botany.
He made use of his own system, because it was extremely convenient for
describing individual plants, but he ascribed all true scientific value
exclusively to the natural system; and with what success he laboured
to advance it may be gathered from the fact, that Bernard de Jussieu
founded his improved series of families on the fragment of Linnaeus,
and that his nephew, A. L. de Jussieu, by simply adopting Linnaeus’
conception of the principle which lies at the foundation of the natural
system, succeeded in carrying it on to a further stage of development.
The main features of Linnaeus’ theoretical botany can best be learned
from the ‘Philosophia Botanica,’ which may be regarded as a text-book
of that which Linnaeus called botany, and which far surpasses all
earlier compositions of the kind in perspicuity and precision, and
in copiousness of material; and indeed it would be difficult to find
in the ninety years after 1781 a text-book of botany which treats
what was known on the subject at each period with equal clearness
and completeness. In giving the reader some idea of the way in which
Linnaeus deals with his subject, it will be well to pass over the
first two chapters, which discuss the literature and the various
systems which had been proposed, and turn to the third, which under
the heading ‘Plantae’ treats of the general nature of plants, and
specially of the organs of vegetation. The vegetable world, says
Linnaeus, comprises seven families, Fungi, Algae, Mosses, Ferns,
Grasses, Palms, and Plants. All are composed of three kinds of vessels,
sap-vessels which convey the fluids, tubes which store up the sap
in their cavities, and tracheae which take in air; these statements
Linnaeus adopts from Malpighi and Grew. He gives no characteristic
marks for the Fungi; of the Algae he says that in them root, leaf,
and stem are all fused together; to the Mosses he ascribes an anther
without a filament, and separate from the female flower which has no
pistil; the seeds of the Mosses have no integument or cotyledons;
this characteristic of the Mosses is explained in his paper entitled
‘Semina Muscorum’ in the ‘Amoenitates Academicae,’ ii. The Ferns are
marked by the fructification on the under side of the fronds, which
are therefore not conceived of as leaves. The very simple leaves, the
jointed stalk, the ‘calyx glumosus,’ and the single seed mark the
Grasses. The simple stem, the rosette of leaves at the summit, and
the spathe of the inflorescence are characteristic of the Palms. All
vegetable forms which do not belong to any of the previous families he
names Plants. He rejects the customary division into herbs, shrubs,
and trees as unscientific. This arrangement of the vegetable kingdom
must not be confounded with Linnaeus’ fragment of a natural system,
in which he adopts sixty-seven families (orders), the Fungi, Algae,
Mosses, and Ferns forming each a family. He evidently introduces the
divisions in the ‘Philosophia,’ in order that it may be seen how far
the statements that follow are applicable to all the Vegetabilia or
only to certain sections of them. The parts in the individual plant
which the beginner must distinguish are three; the root, the herb[31],
and the parts of fructification, in which enumeration Linnaeus departs
from his predecessors, by whom the fructification and the herb together
are opposed to the root. In the central part of the plant is the
pith, enclosed by the wood which is formed from the bast; the bast
is distinct from the rind, which again is covered by the epidermis;
these anatomical facts are from Malpighi; the statement that the pith
grows by extending itself and its envelopes is borrowed from Mariotte.
Cesalpino’s view on the formation of the bud is expressed by Linnaeus
in the statement, that the end of a thread of the pith passing through
the rind is resolved into a bud, etc. The bud is a compressed stem,
capable of unlimited extension till fructification puts a term to
vegetation. The fructification is formed by the leaves uniting into a
calyx, from which the apex of a branch issues as a flower about one
year in advance, while the fruit arising from the substance of the
pith cannot begin a new life till the woody substance of the stamens
has been absorbed by the fluids of the pistil. In this way Linnaeus
corrected Cesalpino’s theory of the flower, that he might take into
account the sexual importance of the stamens discovered by Camerarius.
He concludes by saying that there is no new creation but only a
continuous generation, for which he gives the remarkable and thoroughly
Cesalpinian reason, ‘cum corculum seminis constat parte radicis
medullari.’
The root, which takes up the food, and produces the stem and the
fructification, consists of pith, wood, bast, and rind, and is divided
into the two parts, ‘caudex’ and ‘radicula.’ The ‘caudex’ answers
pretty nearly to our primary root and rhizomes, the ‘radicula’ to what
we now call secondary roots.
The herb springs from the root, and is terminated by the
fructification; it consists of the stem, leaves, leaf-supports
(‘fulcrum’), and the organs of hibernation (‘hibernaculum’). Then
follow the further distinctions of stem and leaves; the terminology,
still partly in use and resting essentially on the definitions of
Jung, is here set forth in great detail. Linnaeus however does not
mention the remarkable distinction between stem and leaf which Jung
founded on relations of symmetry, and in general he shows less depth of
conception than Jung, confining himself more to the direct impression
on the senses, and so distinguishing sometimes where there is no real
difference. Examples of this are furnished by the paragraph devoted
to ‘fulcra.’ By this term he designates the subsidiary organs of
plants, among which he reckons stipules, bracts, spines, thorns,
tendrils, glands, and hairs. It appears from this, that Linnaeus did
not extend the idea of the leaf (‘folium’) to stipules and bracts, and
the examples he gives of tendrils show at the same time that he was
ignorant of the different morphological character of the organ in Vitis
and Pisum. The putting the seven organs above-named together under the
idea of ‘fulcrum’ shows plainly enough that Linnaeus, in framing his
terminology, aimed only at distinguishing what was different to the
sense by fixed words, in order to obtain means for short diagnoses
of species and genera. He had no thought of arriving at more general
propositions from a comparison of forms in plants, in order to attain
to a deeper insight into their nature. The same thing appears from his
notion of ‘hibernaculum,’ by which he understands a part of the plant
which envelopes the stem in its embryonal state and protects it from
harm from without; he here distinguishes bulbs from the winter buds of
woody plants. In this course of mixing up morphological and biological
relations of organs he was followed by botanists till late into our own
century.
Linnaeus goes far beyond his predecessors in distinguishing and naming
the organs of fructification, the subject of the fourth chapter of the
‘Philosophia Botanica.’ The fructification, he says, is a temporary
part in plants devoted to propagation, terminating the old and
beginning the new. He distinguishes the following seven parts: (1) the
calyx, which represents the rind, including in this term the involucre
of the Umbelliferae, the spathe, the calyptra of Mosses, and even the
volva of certain Fungi,—another instance of the way in which Linnaeus
was guided by external appearance in his terminology of the parts of
plants; (2) the corolla, which represents the inner rind (bast) of the
plant; (3) the stamen, which produces the pollen; (4) the pistil, which
is attached to the fruit and receives the pollen; here for the first
time the ovary, style, and stigma are clearly distinguished. But next
comes as a special organ (5) the pericarp, the ovary which contains
the seed. As bulbs and buds were treated not simply as young shoots,
but as separate organs, so here too the ripe fruit is regarded not
merely as the developed ovary, but as a special organ. Nevertheless,
Linnaeus distinguishes the different forms of fruit much better than
his predecessors had done. (6) The seed is a part of the plant that
falls off from it, the rudiment of a new plant, and it is excited to
active life by the pollen. The treatment of the seed and its parts is
the feeblest of all Linnaeus’ efforts; he follows Cesalpino, but his
account of the parts of the seed is much more imperfect than that of
Cesalpino and his successors. The embryo is called the ‘corculum,’ and
two parts are distinguished in it, the ‘plumula’ and the ‘rostellum’
(radicle). The cotyledon is co-ordinated with the ‘corculum,’ and is
regarded therefore not as part of the embryo but as a distinct organ of
the seed; it is defined as ‘corpus laterale seminis bibulum caducum.’
Nothing could be worse, and it seems almost incredible that so bad a
definition and distinction could be given in 1751, and again in 1770,
by the first botanist of his time, when Malpighi and Grew, nearly
a hundred years earlier, had illustrated the parts of the seed and
even the history of its development and its germination by numerous
figures. He does not mention the endosperm, evidently confounding it
with the cotyledon, though Ray had already distinguished it clearly
from the other parts of the seed. Linnaeus’ terminology of the seed
supplies more than sufficient corroboration of our previous remark,
that he shows incapacity for the careful investigation of any object
at all difficult to observe, and it will now seem a small matter that
he, like most of the earlier botanists, treats one-seeded indehiscent
fruits as seeds, and hence makes the pappus a part of the seed. (7) By
the word ‘receptaculum’ he understands everything by which the parts
of the fructification are connected together, both the ‘receptaculum
proprium,’ which unites the parts of the single flower, and the
‘receptaculum commune,’ under which term he comprises the most diverse
forms of inflorescence (umbel, cyme, spadix).
He concludes with the remark that the essence of the flower consists in
the anther and the stigma, that of the fruit in the seed, that of the
fructification in the flower and the fruit, and that of all vegetable
forms in the fructification, and he adds a long list of distinctions
between the organs of fructification with their names; among these
organs appear the nectaries, which he was the first to distinguish.
In the fifth chapter he discusses the question of difference of sex
in plants. His views on this subject have been already mentioned in
order to show that they were entirely founded on worthless scholastic
deductions; here we may quote a few of the propositions which were
famous in after times. We assume, he says, that two individuals of
different sexes were created in the beginning of things in every kind
of living creatures. Plants, though they are without sensation, yet
live as do animals, for they have a beginning and an advance in age
(aetas), and are liable to disease and death; they have also a power
of movement, a natural appetency (propulsio), an anatomy, and an
organic structure (organismus). Simple explanations are given of these
words, but they prove nothing about the matter. He then expounds the
whole theory of sexuality, which is made to rest entirely on scholastic
arguments, and in doing this he spins out to excessive length the
parallel which he draws between the conditions of sexuality in
animals and plants. It is manifestly this chapter of the ‘Philosophia
Botanica,’ together with the treatise ‘Sponsalia Plantarum,’ which led
the adherents of Linnaeus, who were ignorant of the older literature
of the subject and were much impressed by his scholastic dexterity, to
celebrate him as the founder of the sexual theory of plants; whereas
a more careful study of history shows incontrovertibly that Linnaeus
helped in this way to disseminate the doctrine, but did absolutely
nothing to establish it.
The writings of Linnaeus which we have hitherto examined are occupied
with the nature of plants, and of this he knew nothing more than he
gathered from the investigations and reflections of his predecessors;
and it is here especially that his peculiar scholasticism is exhibited
in contrast with the facts obtained by induction which he communicated
to his readers. But the strong side of his intellect appears with
splendid effect in the succeeding chapters of the ‘Philosophia,’ which
treat of the principles of systematic botany; here, where he has
no longer to establish facts, but to arrange ideas, to dispose and
summarise, we find Linnaeus thoroughly in his element.
The groundwork of botanical science, he begins, is twofold,
classification and naming. The constituting of classes, orders, and
genera he calls theoretical classification; the constituting of species
and varieties is practical classification. The work of classification
carried out by Cesalpino, Morison, Tournefort, and others leads to the
establishing of a system; the mere practice of describing species may
be carried on by those who know nothing of systematic botany. These
expressions of Linnaeus are interesting, because like other remarks of
his they show that he placed the establishment and arrangement of the
larger groups above the mere distinguishing of individual forms; his
disciples to a great extent forgot their master’s teaching, and fancied
that the collecting and distinguishing of species was systematic
botany. He opposes the system itself, which deals with the relative
conceptions of classes, orders, genera, species, and varieties, to a
mere synoptical view, serving with its dichotomy only to practical
ends. Then comes the often-quoted sentence, ‘We reckon so many species
as there were distinct forms created “in principio.”’ In a former
place he had said ‘ab initio’ instead of ‘in principio’; instead
therefore of a beginning in time he here posits an ideal, theoretical
beginning, which is more in accordance with his philosophical views.
That new species can arise is, he continues, disproved by continuous
generation and propagation, and by daily observation, and by the
cotyledons. It is hard to understand how the Linnaean school till far
into our own century could have remained firm in a doctrine resting
on such arguments as these. Linnaeus’ definition of varieties shows
that he understood by the word species fundamentally distinct forms;
there are, he says, as many varieties as there are different plants
growing from the seed of the same species; and he adds that a variety
owes its origin to an accidental cause, such as climate, soil, warmth,
the wind; but this is evidently mere arbitrary assumption. Judging by
all he says, his view is that species differ in their inner nature,
varieties only in outward form. Here, where we find the dogma of the
constancy of species for the first time expressed in precise terms,—a
dogma generally accepted till the appearance of the theory of descent,
we should be justified in demanding proof; but since dogmas as a rule
do not admit of proof, Linnaeus simply states his view[32], unless we
are to take the sentence, ‘negat generatio continuata, propagatio,
observationes quotidianae, cotyledones,’ as proving the assertion that
new species never appear. We shall see further on to what surprising
conclusions Linnaeus was himself led by his dogma, when he had to take
into account the relations of affinity in genera and larger groups. The
species and the genus, he continues, are always the work of nature,
the variety is often that of cultivation; the class and the order
depend both on nature and on art, which must mean that the larger
groups of the vegetable kingdom have not the same objective reality as
the species and the genus, but rest partly on opinion. That Linnaeus
estimated the labours of the systematists after Cesalpino and the
contributions of the German fathers of botany up to Bauhin, as they
have been judged of in the present work, is shown by paragraph 163,
where he explains the word habit, and adds that Kaspar Bauhin and the
older writers had excellently divined (divinarunt) the affinities of
plants from their habit, and even real systematists had often erred,
where the habit pointed out to them the right way. But he says that the
natural arrangement, which is the ultimate aim of botany, is founded,
as the moderns have discovered, on the fructification, though even
this will not determine all the classes. It is interesting therefore
to observe how Linnaeus further on (paragraph 168) directs, that in
forming genera, though they must rest on the fructification, yet it is
needful to attend to the habit also, lest an incorrect genus should
be established on some insignificant mark (levi de causâ): but this
attention to the habit must be managed with reserve, so as not to
disturb the scientific diagnosis.
Linnaeus next lays down with great detail each several rule, which
must be observed in establishing species, genera, orders, and
classes, and it is here that he displays his unrivalled skill as a
systematist. These rules were strictly observed by himself in his
numerous descriptive works, and thus a spirit of order and clearness
was introduced into the art of describing plants, which gave it at once
a different appearance from that which it had received at the hands of
his predecessors. Whoever therefore compares the ‘Genera Plantarum,’
the ‘Systema Naturae,’ and other descriptive works of Linnaeus with
those of Morison, Ray, Bachmann, or Tournefort, finds so great a
revolution effected by them, that he is impressed with the persuasion
that botany first became a science in the hands of Linnaeus; all
former efforts seem to be so unskilful and without order in comparison
with his method. Without doubt the greatest and most lasting service
which Linnaeus rendered both to botany and to zoology lies in the
certainty and precision which he introduced into the art of describing.
But if a reformation was thus effected in botany, as Linnaeus
himself took pleasure in saying, it must not be overlooked that the
knowledge of the nature of plants was rather hindered than advanced
by him. Ray, Bachmann, and in part also Morison and Tournefort, had
already liberated themselves to a great extent from the influence of
scholasticism, and they still give us the impression of having been
genuine investigators of nature; but Linnaeus fell back again into the
scholastic modes of thought, and these were so intimately combined with
his brilliant performances in systematic botany, that his successors
were unable to separate the one from the other.
The feeling for order and perspicuity, which made Linnaeus a reformer
of the art of describing, combined with his scholasticism, was
evidently the cause of his not bestowing more energetic labour on
the natural system. It has been repeatedly mentioned that it was
he who first established sixty-five truly natural groups in his
fragment of the early date of 1738; and a certain feeling for natural
affinity is shown in the establishment of his seven families, Fungi,
Algae, Mosses, Ferns, Grasses, Palms, and Plants properly so-called.
Moreover in paragraph 163 of the ‘Philosophia Botanica,’ he carries
out the division of the whole vegetable kingdom into Acotyledons,
Monocotyledons, and Polycotyledons with their subdivisions very
admirably; and thus we see him continually impelled towards a natural
arrangement, but never bestowing upon it the necessary labour and
thought.
And so two different conceptions of a system of plants continued to
subsist side by side with each other in the mind of Linnaeus; one more
superficial, and adapted for practical use, expressed in his artificial
sexual system, and one more profound and scientifically valuable,
embodied in his fragment and in the natural groups above-mentioned.
The same may be said also of Linnaeus’ morphological views; here,
too, a more superficial pursued its way along with a more profound
conception. He formed his terminology of the parts of plants for
practical use in describing them, and convenient as it is, it seems
nevertheless shallow or superficial, because its foundations are not
more deeply laid in the comparative study of forms. But we discover
from very various passages in his writings that he felt the need of
a more profound conception of plant-form, and what he was able to
say on the subject he put together under the head of ‘metamorphosis
plantarum.’ His doctrine of metamorphosis is entirely based on the
views of Cesalpino, with which we have already become acquainted,
though he did not adopt them in their original form, but endeavoured
to develop them in true Cesalpinian fashion; for on the one hand he
derived leaves and parts of flowers from the tissues of the stem, and
on the other conceived of the parts of the flower as only altered
leaves. This doctrine of metamorphosis appears in somewhat confused
form in the last page of his ‘Philosophia Botanica.’ There he says that
the whole of the herb is a continuation of the medullary substance of
the root; the principle of the flowers and leaves is the same, because
both spring from the tissue-layers surrounding the pith, as Cesalpino
had taught. The statement which follows, that the principle of the bud
and the leaves is identical, would be a departure from Cesalpino, and
in any case inconsistent, without the explanation that the bud consists
of rudimentary leaves; but this again puts the axial portion of the bud
out of sight. The perianth, he says, comes from concrescent rudiments
of leaves. How closely Linnaeus adhered to Cesalpino in his later years
appears in his explanation of the catkin, which comes next and which
is taken entirely from Cesalpino’s theory. That a more superficial and
a more profound conception pursue their way together unadjusted in
Linnaeus’ speculations on form is specially shown by the fact, that in
the text of the ‘Philosophia Botanica,’ paragraph 84, he places the
‘stipulae’ under the idea of ‘fulcra’ and not under that of ‘folia,’
while on the contrary at the end of the same work, where he brings
together the different paragraphs respecting metamorphosis, he speaks
of the ‘stipulae’ as appendages of the leaves.
The idea of Cesalpino, that the parts of the flower which surround the
fruit arise like the ordinary leaves from the tissues that enclose
the pith, is further developed by Linnaeus in his ‘Metamorphosis
Plantarum,’ in the fourth volume of the ‘Amoenitates Academicae’
(1759), in a very strange manner. He compares the formation of the
flower with the metamorphosis of animals, and especially of insects,
and after describing the changes that take place in animals, he says at
page 370 that plants are subject to similar change. The metamorphosis
of insects consists in the putting off different skins, so that
they finally come forth naked in their true and perfect form. This
metamorphosis we also find in most plants, for they consist, at least
in the truly living part of the root, of rind, bast, wood, and pith.
The rind is to the plant what the skin is to the larva of an insect,
and after putting this skin off there remains a naked insect. When
the flower is produced in the plant the rind opens and forms the calyx
(exactly Cesalpino’s view), and from out of this the inner parts of the
plant issue to form the flower, so that the bast, the wood, and the
pith issue forth naked in the form of corolla, stamens, and stigma. So
long as the plant lies concealed within the rind and clothed only with
leaves, it appears to us as unrecognisable and obscure as a butterfly,
which in its larva-condition is covered with skin and spines.
In this doctrine of metamorphosis, which Linnaeus founded on Cesalpino,
the chief point to observe is, that the ordinary leaves are identical
with the exterior parts of the flower, because both originate in the
outer tissues of the stem. The pertinent fact, which may easily be
observed without a microscope, that the concentric arrangement of
outer and inner rind, wood, and pith occurs only in some flowering
plants, that the case is quite different with Monocotyledons, and
that Cesalpino’s theory of the flower cannot properly be applied to
them,—these are things which we must not expect to find Linnaeus with
his peculiar modes of thought taking into consideration.
The want of firm standing-ground in experience is shown also by the
fact, that with his own and Cesalpino’s theory of the flower he
combined another view of its nature, which under the name of ‘prolepsis
plantarum’ was set forth in two dissertations in 1760 and 1763, but
the two theories are scarcely compatible with one another. While the
last paragraph in the ‘Philosophia Botanica’ says, ‘Flos ex gemmâ
annuo spatio foliis praecocior est,’ the dissertations contain the
doctrine[33], that the flower is nothing but the synchronous appearance
of leaves, which properly belong to the bud-formations of six
consecutive years, in such a way that the leaves of the bud destined to
be unfolded in the second year of the plants become bracts, the leaves
of the third year the calyx, those of the fourth the corolla, those of
the fifth the stamens, those of the sixth the pistil. Here we see once
more how Linnaeus moves in the sphere of arbitrary assumptions with no
thought of exact observation, for this whole theory of prolepsis rests
on nothing that can be called a well-ascertained fact.
Yet a third time we find in Linnaeus the juxtaposition of a superficial
view resting on every-day perception, and a more profound and to some
extent a philosophical view; this is the case where he is concerned on
the one hand with the dogma of the constancy of species, and on the
other hand has to explain the fact of natural relationship and its
gradations. Apart from some insignificant verbal explanations, Linnaeus
adduced nothing in support of the dogma but the every-day perception of
the unchangeableness of species, and to this he held fast to the end
of his life; but it was important to find an explanation of the fact,
to which he himself repeatedly drew attention, that genera, orders,
and classes do not merely rest on opinion but indicate really existing
affinities. His mode of solving the difficulty was a very remarkable
one; not only does the scholastic manner of thought appear here again
quite unalloyed by modern science, but he grounds his explanation once
more on the old _a priori_ notion that the pith is the vital principle
in the plant, and also on his own assumption, that in the sexual act
the woody substance of the anthers combines with the pith-substance of
the pistil. Hugo Mohl has given a clear account of the matter in No. 46
of the ‘Botanische Zeitung’ for 1870, although neither he nor Wigand
nor most of Linnaeus’ biographers seem to know, that his theories are
all to be traced to Cesalpino. Linnaeus’ theory of natural affinities,
as he gave it in 1762 in the ‘Fundamentum Fructificationis,’ and in
1764 in the sixth edition of the ‘Genera Plantarum,’ is as follows: At
the creation of plants (in ipsa creatione) one species was made as the
representative of each natural order, and these plants so corresponding
to the natural orders were distinct from one another in habit and
fructification, that is, absolutely distinct. In the communication of
1764 the following words occur:—
1. Creator T.O. in primordio vestiit vegetabile medullare principiis
constitutivis diversi corticalis, unde tot difformia individua, quot
ordines naturales, prognata.
2. Classicas has plantas Omnipotens miscuit inter se, unde tot genera
ordinum, quot inde plantae.
3. Genericas has miscuit natura, unde tot species congeneres, quot
hodie existunt.
4. Species has miscuit casus, unde totidem quot passim occurrunt
varietates.
Hugo Mohl was right in rejecting Heufler’s assumption that a view
resembling the modern theory of descent was contained in these
paragraphs. It must be plain to any one who knows the ideas of
Aristotle, Theophrastus, and Cesalpino, within the sphere of which
Linnaeus is here moving, what he understands by his ‘vegetabile
medullare’ and ‘corticale’; that he does not for a moment mean a plant
of simplest organisation, but that both expressions indicate only
the original elements of vegetation which the Creator, according to
Linnaeus, united to one another at the first. He assumed that plants of
the highest and of the lowest grades of organisation were originally
created at the same time and alongside of one another; no new
class-plants were afterwards created, but from the mingling together
of the existing ones by the act of the Creator generically distinct
forms were produced, and the natural mingling of these gave birth to
species, while varieties were mere chance deviations from species. But
it is to be noticed that in these minglings or hybridisations the woody
substance of the one form which supplies the pollen is united with the
pith-substance of the other form, whose pistil is thus fertilised; and
so in these supposed crossings it is always the two original elements
of the plant, the medullary and the cortical, which are mingled
together.
No further proof is wanting that this theory of Linnaeus is no
precursor of our theory of descent, but is most distinctly opposed to
it; it is utterly and entirely the fruit of scholasticism, while the
essential feature in Darwin’s theory of descent is that scholasticism
finds no place in it.