of you have heard of the fact and are ready to vouch
for it in Scotland there is one sort of tree more
peculiar than others ; the leaves which fall on the
ground yield birds, while those which fall into water
are soon changed into fishes. There is no doubting
the fact, as the scene is very distinctly depicted
in an old wood-engraving. A photograph, how-
ever, would be more convincing, but then Daguerre
and Niepce had not made their appearance at that
time.
It may be remarked that some seventy years later
Father Kircher, in his Mundus Subterraneus? still
believed in many strange notions of the same sort, and
depicted the genesis of birds, apes, and men by means
of the transformation of some orchids. He had been
1 The full title is : Histoire admirable des Piantcs et Herbes esmer-
veillables et miractileuscs en Nature, mesmes d'aticunes qui s.ont vrays
Zoophytes on Plantes Animalcs .... avec I cur Portraits att natwel.
1 8. Paris, Nicolas Brion, 1609.
2 Amsterdam, 2. vols. in folio, 1678.
DE MA1LLET 15
struck with the resemblance of these strange flowers
to many animals, and therefore concluded that the
latter were derived from the former.
In the meantime De Maillet, French consul in
Leghorn and in Egypt during a number of years,
wrote, at the end of his life, a strange book called
Telliamed^ (his own name reversed). The greater
part of it has little to do with the matter under dis-
cussion, but in the last ninety pages, after having
considered the real nature of fossils a question at
that time much discussed, and concerning which the
truth became established only after numerous diffi-
culties De Maillet concerns himself with the origin
of man and animals. His main idea is that all
terrestrial and aerial animals have their origin in some
corresponding marine form. For instance, birds are
derived from flying fishes, lions from sea-lions, &c.,
and man from the " homme marin" the husband of the
mermaid. The reason he gives for these derivations
is curious enough. Considering the many islands
there were more of them in his time than at the
present day which, although uninhabited by man,
contain animals and plants, he argues that if these
animals and plants are not derived from marin
1 Telliamed ; ou, Entretiens (fun Philosophe Indien avec un Missio-
naire Francais, etc. , mis en ordre sur les Mtmoires de fen M. de Maillet.
Basle, 1749.
16 EXPERIMENTAL EVOLUTION LECT.
forms, "we must assume a new creation, which is
absurd" (p. 313).
Some years after De Maillet, another French writer
gave utterance to more valuable notions concerning
evolution. This author was J. B. Robinet. There is but
little to interest us in his book, De la Nature, published
in 1 766 (four Svo volumes, Amsterdam,) but his Vues
philosophiques de la gradation naturelle des Formes de
FEtre, ou les Essais de la Nature qui apprend a faire
r Homme (1768, Amsterdam,) contain curious passages.
For instance, he clearly recognized the fact that all
animals are in many points similar, and that if the
similarity between any two animals at the opposed
ends of the organic scale is difficult to perceive when
they aie considered apart from the others, numerous
transitional forms occur, and are real connecting links
when the whole scale is taken into consideration.
Robinet supposes that Nature has an aim, a con-
stant tendency towards perfection, and towards perfec-
tion of a given type. Since the beginning the aim of
Nature has been to prepare man, and the proofs
thereof are not wanting, according to Robinet. These
proofs are the numerous stones or fossils which bear a
more or less vague resemblance to the organs and
various parts of man, monstrous turnips and extra-
ordinary cabbages, in the form of a hand, a nose, or
an ear, or other parts of the body, whether internal or
I ROBINET AND BUFFON 17
external. Robinet is not very clear about the method
which Nature followed in order to attain her object,
but the last part of his story is quite fluent, and the
ape appears as the last effort of Nature before she
succeeded in making man.
This is very crude and elementary evolutionism, to
be sure, and the names of Robinet, De Maillet, and
Duret l have but slight historical interest, but it must
be remembered that between Robinet and Darwin not
a century elapsed, and there lies the reason for which
I have wished to recall briefly the quaint notions of
these transformists of the past A word, however,
may be said in their defence ; we must remember
that at the time they wrote, little was known concern-
ing species, and no idea could be obtained concerning
their origin and derivation, so long as their nature was
ignored.
Evolutionism, scientific and really deserving this
name, appeared only a few years after the publication
of Robinet's ungainly views, and here the French
scientists took a prominent part.
Buffon comes first. Much has been said and
written concerning the orthodoxy of the great natural-
ist, and contradictory statements have been made, so
1 For details concerning their theories cf. Henry de Varigny : La
Philosophic Biologique aux xvii 1 ' el xmii e Siccles, l\.evt(e Scientijiyuc,
August 29th, 1889. Also De Quatrefages, Charles Darwin et ses Pre-
curseurs francaiS) 1870, of which anew edition is in the press (1892).
C
J8 EXPERIMENTAL EVOLUTION LECT.
that many know not whether he is to be accounted
as a friend or as a foe. The truth is that Buffon's
views on the unity of species lacked unity themselves.
From 1753 to 1756, it is quite clear, as Geoffroy Saint
Hilaire has shown, that he believed in their immut-
ability. "Species in animals," he says, "are all
separated from each other by an interval which Nature
cannot cross." Later on, his writings show a different
turn of mind, and from 1761 to 1766, more particularly
give evidence thereof. " One is surprised at the prompt-
ness with which the species vary, and at the ease with
which they become altered and assume new forms."
This theory of the mutability of species he con-
sidered, some years later, to be rather exaggerated,
and he returned to more moderate views, though not
abandoning the theory of variability and mutability,
which, in his opinion, are due to the direct influence
of environment.
After Buffon comes Lamarck, a friend and pupil of
the former. Lamarck was the first to state distinctly,
in any developed form, the theory of the variability
and transmutation of species, which many had before
him briefly proposed or supposed, and he tried to dis-
cover the cause of this variability. 1 The facts of varia-
1 See his Philosophic ZoologicjJie, 1809 ; Introduction a FHistoire
naturelle des Animaux sans Verlebres, 1815 ; and Systeme de Con-
naissances positives ', 1820.
I LAMARCKIAN THEORY 19
bility were supplied to him by all sorts of animals, and
in part by the domesticated forms, and among these
the pigeon and fowl, of which, later, Darwin made
great use. Lamarck believed in spontaneous genera-
tion under laws given by a Creator of elemen-
tary organisms which became gradually perfected and
transformed into higher beings, under other laws which
Lamarck recognized and stated. Among these laws is
that of the hereditary transmission of acquired char-
acters, which is at present so much discussed, after
Weismann's opposition. As to the cause of variability,
it is to be found, says Lamarck, in " new needs of the
organism," so that the influence of environment plays
but an accessory part. Whatever opinions may be
entertained as to the views of this naturalist concern-
ing the causes and methods of variation, it must be
conceded that he was the first clearly to perceive and
state the problem of the origin of species.
Geoffrey Saint Hilaire (Etienne) was rather a
disciple of BufFon than of Lamarck. He believed
much in the influence of environment 1 and fought
hard against Cuvier and his views, while Bory de
Saint Vincent upheld the views of Lamarck. Of
Geoffroy Saint Hilaire we shall have to speak again
further on. We do not pretend to give here any com-
1 See his Sttr le Degre if Influence du Monde ambiant po^lr modifier
es Formes animates.
C 2
EXPERIMENTAL EVOLUTION LECT.
plete account of the progress of the Evolution theory-
more especially after having announced our desire to
restrict ourselves chiefly to French naturalists and
shall dwell no longer on this point of history. It
must be recalled, however, that Linnaeus, in 1762
(Amcenitates] had expressed the idea that all species
of the same genus ab initio unam constituerunt speciem,
without saying, however, how the differentiation of
he primitive one species into many had taken place.
Moreover many writers whose names are given by
Darwin in his Origin of Species, anticipated him more
or less, not in his explanation of the quomodo of trans-
mutation, but in the statement of the fact, or theory.
There is, however, one name to which attention
must be called ; it is that of Naudin, the veteran French
botanist, who, in 1852, published a very interesting
paper in the Revue Horticole (1852, p. 102). As he
recently wrote to me x this paper was published
by the editors of the Revue with much diffidence ;
they cared little about theoretical discussions, and the
hypothesis of transmutation was " nowhere " in their
opinion. Some passages are of much interest, and
may be quoted here.
1 " The editors of the Revue Horticole did not feel inclined to
allow such heretical notions to be expounded in it ; they accepted the
paper, however, throwing the whole responsibility upon myself, and
fearing to injure their orthodoxy through an irhpure alloy." (Letter,
dated March 6th, 1891.)
I NAUDIN (1852) 21
" We do not think that Nature has made her species
in a different fashion from that in which we proceed
ourselves in order to make our variations. To say the
truth, we have practised her very method. When we
wish, out of some zoological or botanical species, to
obtain a variety which answers to such or such of our
needs, we select (choisissons) out of the large number of
the individuals of this species, so as to make them the
starting point of a new stirp, those which seem already
to depart from the specific type in the direction which
suits us, and, by a rational and continuous sorting of
the descendants, after an undetermined number of
generations we create types or artificial species, which
correspond more or less with the ideal type we had
imagined, and which transmit the acquired characters
to their descendants in proportion to the number of
generations upon which our efforts have been bearing.
Such is, in our opinion, the method followed by Nature;
as well as by ourselves ; she has wished to create races
conformable to her needs, and, with a comparatively
small number of primitive types, she has successively,
and at different periods, given birth to all the animal
and vegetable species which people the earth." . . .
This says nothing of the reason for which Nature
follows such a method, but the method is exactly that
which we know under the name of natural selection and
artificial selection. It seems fair to say that Naudin's
22 EXPERIMENTAL EVOLUTION LECT.
name deserves a high place in the history of the rise
and progress of evolutionary thought, and the paper to
which I allude is not generally well known, even to
writers familiar with the subject of evolution. Of
Darwin's work I shall say nothing : all are familiar
with the principles which lie at the root of his theory ;
but it would be unfair not to put Herbert Spencer's
name on the list, close to his.
And now we may briefly recapitulate the theories
which have been proposed on both sides to explain
the present condition of the organic world.
On the special creation side we meet with four
distinct views :
(1) Our planet, long uninhabited, has become
peopled with the types and forms it now contains, from
another planet in which these existed, and which has
fallen on ours.
This hypothesis might be discussed by savages
or by lunatics ; to me it seems useless to show
its failure, of which the least is that it merely
puts off the problem without any attempt towards
solving it.
(2) All species have been specially created from
the beginning of the world a very elastic term, to be
sure and have lived in part, or in whole, until the
present day, without any alteration.
This hypothesis is untrue, as it is known that most
I SPECIAL CREATION THEORIES 23
living species occur only very seldom in strata of some
antiquity, and that the present fauna, for instance, is
quite different from the various faunas which lived in
the different geological epochs.
(3) A large number of living beings specially
created at the beginning, having been killed by various
cataclysms, they have been created anew after
the catastrophes which, in Cuvier's opinion, are the
necessary concomitants of every geological epoch.
This is Cuvier's hypothesis of the " revolutions of
the earth." It may seem somewhat puerile to sup-
pose that the Creator has seen His own doing turn
against Him, and oblige Him to begin His work
anew, on repeated occasions.
(4) All species have been specially created from
the beginning, but while some die out gradually, other
new ones put in a sudden appearance, for reasons
hitherto unexplained.
This is only a part of an hypothesis, as it does not
explain why or how new species appear, which is
exactly the problem to be solved.
On the adverse, non-special creation side, we have
only one hypothesis, the evolutionary one, which sup-
poses all living species to have been evolved from
antecedent and different organisms all organisms
having perhaps been evolved out of a single ele-
mentary one, born we know not how, but certainly
24 EXPERIMENTAL EVOLUTION LECT.
created, unless we can believe that matter, energy,
and life can originate spontaneously.
Between the Special Creation and the Evolution
theory the contest has been a fierce one, for reasons
already given ; but it may be said that at the present
moment the last-named has gathered around it the
greater army.
But it must be confessed, at the same time, that
no positive and direct proof of the truth of the evo-
lutionary theory has yet been given. It is true none
can be given either of the opposite theory. In the
very year, 1852, in which Naudin gave utterance
to his theory of the origin of species by means of
selection, Herbert Spencer published a short essay
on the Development Hypothesis, which has been re-
publishccl in his recent edition of Essays, as the first
of the whole series. In this essay he speaks of the
anti-evolutionists, who argue that " as in all our
experience we know no such phenomenon as trans-
mutation of species, it is unphilosophical to assume
that transmutation of species ever takes place," and
forget that " as in all our experience we have never
known a species created, it is unphilosophical to
assume that any species, has ever been created."
We cannot exactly adhere to this reasoning. If
species have been created, they may have been so
before man could see them, while if species are
I ARGUMENTS FOR EVOLUTION 25
derived from each other by evolution, there is no
reason why the process should not be at all times
going on, and why man should not witness it. So,
on that point, creationists are entitled to ask of evo-
lutionists demonstrations which, conversely, the latter
cannot require from the former.
Without proceeding to discuss more amply the
matter so very well discussed by Herbert Spencer
in this essay, I wish to recall briefly to your memory
the general proofs of organic evolution as they are
known at present.
One of these proofs, or arguments, is that which
results from palaeontological studies. Broadly speak-
ing, an evolution in the animal and vegetable king-
doms is indicated by the fact that the older strata
of the earth contain organisms which are simpler than
those which are contained in the newer, or are living
at present. For instance, no Vertebrates are known
in the Silurian strata save some lowly-organized
fishes, and it is only in later deposits that the other
groups put in an appearance. Of course, much may
be said, even now, concerning the provisional con-
dition of our palaeontological knowledge. We know
but little of the contents of the geological strata, and
of the greater part of the globe we are totally igno-
rant. Future investigations and discoveries may con-
siderably alter the present situation ; and, on the
26 EXPERIMENTAL EVOLUTION LECT.
other hand, our geological notions may require im-
portant alterations as concerns synchronism and
heterochronism of the strata and of their contents.
It may happen that vestiges of animals which we
consider as very recent may be found in much older
strata ; it may also happen that some types have
been evolved in very limited portions of the globe
at different times and with different characters. It
may be granted that our geological conceptions re-
quire to be revised, and in many cases altered. But
however fragmentary and imperfect our present know-
ledge may be, it nevertheless yields important con-
clusions. Through palaeontology we perceive in some
cases the passage from one group of animals to
another, and while theory shows that birds are
probably in close relationship with reptiles, the
Jurassic strata yield ArcJiceopteryx lithographic^
which partakes of the character of both groups, and
in the more recent Tertiary deposits we meet with
many forms which have now disappeared, but are in
intimate connection with the existing species of many
orders, and seem positively to be the ancestors from
which the latter have been evolved with slight modifi-
cations. It is enough to recall the important investi-
gations of Gaudry, Leidy, Falconer, Cope, Marsh,
Boyd-Dawkins, and Lartet, who have traced, with the
utmost probability, the exact line of descent from
PALAEONTOLOGICAL ARGUMENTS 27
those fossil forms of older strata to those which live
at the present time.
Palaeontology shows in some cases the process of
evolution in much detail. I may refer to the researches
of Hilgendorf and Hyatt, at Steinheim in Wiirtem-
bcrg. They show that while the different species of
Planorbis, when considered in the most recent of
these strata, are very dissimilar, if the series is studied
from the lower to the upper ones, it is easily seen
that out of four initial forms, not very different from
each other, slightly different forms have in the course
of time originated, becoming, as we consider more
recent strata, always more diversified, always more
different from their ancestors, and from one another.
While the origin is the same, the results are quite
dissimilar, and if the older strata were wanting,
no possible link could be found between the very
dissimilar forms which co-exist in the more recent
deposits, no line of descent or of relationship could
be established. Investigations of less recent elate than
those of Hyatt have afforded identical results. In
his important work on the Foraminifera, 1 Terquem has
shown the forms which are intermediate between types
which at first glance seem very dissimilar ; and Rupert
Jones more recently, in his " Remarks on the Fora-
1 Recherches sur les Foraminifcrcs du Lias du Dtpartement de la
Moselle. 1858-1866,
28 EXPERIMENTAL EVOLUTION LECT.
minifera, with especial reference to their Variability
of Form, illustrated by the Cristellarians " {Monthly
Microscopical Journal, 1 876), has worked out the same
matter, with the same general result.
Palaeontology, upon the whole, although yet very
fragmentary and incomplete, testifies to the truth of
evolution, showing an unmistakable line of descent
from ancient types of life to more recent types, and
from these more recent types to those which live now.
I do not mean to say that in the case of every animal
we are enabled to trace its ancestry with exactness
to the most remote times, but in many cases this
ancestry admits of being very satisfactorily traced,
and, with the future progress of geology and palae-
ontology, many gaps will be filled up, and many
connecting links discovered.
Among recent books French books well illus-
trating the preceding statements, I would recommend
those which M. Gaudry, professor of palaeontology in
the French Natural History Museum, and one of the
leading evolutionists in France, has published, under
the significant title of Les Enchainements du Monde
Animal dans les Temps Geologiques. These three
volumes are entirely devoted to the question of palae-
ontological descent, and are most ably written and
reasoned.
Another argument for evolution is derived from
I EMBRYOLOGICAL ARGUMENTS 29
the facts of embryology. Embryology is merely an
evolution, and to study the development of any given
organism is to study its evolution from a single ele-
mentary cell the egg-cell to the stage when this
has become capable of leading an independent or
semi-independent life, and has acquired a form and
complexity of structure which are truly marvellous.
In many cases this evolution lasts some weeks, some
months at the longest, and the organism thus evolved
merely needs to acquire larger dimensions by growth ;
but in many cases also there are breaks in the evo-
lution process, and when one point is attained the
process stops for some time, and is resumed later on.
Such is the case in most butterflies where the evolution
or development takes place in two or three periods,
the adult period being singularly short, and some-
times hardly exceeding a few hours, during which
reproduction is the only function accomplished, and,
in fact, the butterfly stage of life has no other object
than reproduction.
This process of evolution is a most marvellous one.
While the brain the minute speck of brain of an
ant may well cause the naturalist and thinker to
wonder, by reason of the varied and complex acts it
originates, the mere cell out of which a most complex
organism with innumerable functions develops in the
course of a few years, yielding a brain such as that
30 EXPERIMENTAL EVOLUTION LECT.
of a Pascal, a Lavoisier, a Newton, a Goethe, a Shake-
speare, a Pasteur, or a Darwin, becomes to the natur-
alist a subject of meditation still more extraordinary
and astounding. This form of evolution is to be seen
in all organisms, save in the simpler ones where no
process of reproduction is present except mere division,
and where the organism consists of mere cells one or
more without any specialized organs and functions.
There is a striking sameness in the development
of animals of the same group, however much they
may differ from each other when they attain the
adult form. Such is the case, for instance, with many
parasitic crustaceans. While the adult Sacculina, for
example, is a mere mass of suctorial appendages
converging towards an alimentary canal, and presents
not a single one of the external characters of any
adult crustacean, development shows the character-
istic form of the crustacean larva, and no doubt can be
felt as to the real nature, affinities, and systematic
position of the degenerate adult, however unlike the
general crustacean type it may be.
This individual evolution is named ontogeny, as all
know, and evolutionary naturalists consider it as repeat-
ing, under a condensed and abridged form, the evolution
of the species, or group, that is to say the pJiylogeny
or palaeontological evolution. And while the study of
the transitional phases in individual evolution shows
I EMBRYOLOGICAL ARGUMENTS 31
the real relation between forms sometimes very dis-
similar in adult age, it shows also the probable origin
of the group or species under consideration. Why
should a tadpole begin as a fish having' gills and
the circulatory system belonging to fishes although
destined to become something very different from a fish,
if there is not some intimate relationship between am-
phibians and fishes, if amphibians have not their origin
in fishes, if amphibians are not transformed fishes ?
And, if we turn towards man, who, according to the
evolutionary hypothesis, is no more than the last result
of the evolution of higher vertebrates, we meet with
facts identical in nature, but more surprising still.
Mammals must be considered as having been evolved
out of lower vertebrates, exactly as amphibians must
have been evolved out of fishes, and as all vertebrates
must, in different lines, have been evolved from fishes,
man's development or embryology should retain some