Darwin and Modern Science
by
A.C. Seward
Part 8 out of 14
the greater generic and specific affinity with East Asia than with West
America." ("More Letters", I. page 434.) The recent discoveries of a
Tulip tree and a Sassafras in China afford fresh illustrations. A few
years later Asa Gray found the explanation in both areas being centres of
preservation of the Cretaceous flora from a common origin. It is
interesting to note that the paper in which this was enunciated at once
established his reputation.
In Europe the latitudinal range of the great mountain chains gave the
Miocene flora no chance of escape during the Glacial period, and the
Mediterranean appears to have equally intercepted the flow of alpine plants
to the Atlas. (John Ball in Appendix G, page 438, in "Journal of a Tour in
Morocco and the Great Atlas", J.D. Hooker and J. Ball, London, 1878.) In
Southern Europe the myrtle, the laurel, the fig and the dwarf-palm are the
sole representatives of as many great tropical families. Another great
tropical family, the Gesneraceae has left single representatives from the
Pyrenees to the Balkans; and in the former a diminutive yam still lingers.
These are only illustrations of the evidence which constantly accumulates
and which finds no rational explanation except that which Darwin has given
to it.
The theory of southward migration is the key to the interpretation of the
geographical distribution of plants. It derived enormous support from the
researches of Heer and has now become an accepted commonplace. Saporta in
1888 described the vegetable kingdom as "emigrant pour suivre une direction
determinee et marcher du nord au sud, a la recherche de regions et de
stations plus favorables, mieux appropriees aux adaptations acquises, a
meme que la temperature terrestre perd ses conditions premieres."
("Origine Paleontologique des arbres", Paris, 1888, page 28.) If, as is so
often the case, the theory now seems to be a priori inevitable, the
historian of science will not omit to record that the first germ sprang
from the brain of Darwin.
In attempting this sketch of Darwin's influence on Geographical
Distribution, I have found it impossible to treat it from an external point
of view. His interest in it was unflagging; all I could say became
necessarily a record of that interest and could not be detached from it.
He was in more or less intimate touch with everyone who was working at it.
In reading the letters we move amongst great names. With an extraordinary
charm of persuasive correspondence he was constantly suggesting,
criticising and stimulating. It is hardly an exaggeration to say that from
the quiet of his study at Down he was founding and directing a wide-world
school.
POSTSCRIPTUM.
Since this essay was put in type Dr Ernst's striking account of the "New
Flora of the Volcanic Island of Krakatau" (Cambridge, 1909.) has reached
me. All botanists must feel a debt of gratitude to Prof. Seward for his
admirable translation of a memoir which in its original form is practically
unprocurable and to the liberality of the Cambridge University Press for
its publication. In the preceding pages I have traced the laborious
research by which the methods of Plant Dispersal were established by
Darwin. In the island of Krakatau nature has supplied a crucial experiment
which, if it had occurred earlier, would have at once secured conviction of
their efficiency. A quarter of a century ago every trace of organic life
in the island was "destroyed and buried under a thick covering of glowing
stones." Now, it is "again covered with a mantle of green, the growth
being in places so luxuriant that it is necessary to cut one's way
laboriously through the vegetation." (Op. cit. page 4.) Ernst traces
minutely how this has been brought about by the combined action of wind,
birds and sea currents, as means of transport. The process will continue,
and he concludes:--"At last after a long interval the vegetation on the
desolated island will again acquire that wealth of variety and luxuriance
which we see in the fullest development which Nature has reached in the
primaeval forest in the tropics." (Op. cit. page 72.) The possibility of
such a result revealed itself to the insight of Darwin with little
encouragement or support from contemporary opinion.
One of the most remarkable facts established by Ernst is that this has not
been accomplished by the transport of seeds alone. "Tree stems and
branches played an important part in the colonisation of Krakatau by plants
and animals. Large piles of floating trees, stems, branches and bamboos
are met with everywhere on the beach above high-water mark and often
carried a considerable distance inland. Some of the animals on the island,
such as the fat Iguana (Varanus salvator) which suns itself in the beds of
streams, may have travelled on floating wood, possibly also the ancestors
of the numerous ants, but certainly plants." (Op. cit. page 56.) Darwin
actually had a prevision of this. Writing to Hooker he says:--"Would it
not be a prodigy if an unstocked island did not in the course of ages
receive colonists from coasts whence the currents flow, trees are drifted
and birds are driven by gales?" ("More Letters", I. page 483.) And ten
years earlier:--"I must believe in the...whole plant or branch being washed
into the sea; with floods and slips and earthquakes; this must continually
be happening." ("Life and Letters", II. pages 56, 57.) If we give to
"continually" a cosmic measure, can the fact be doubted? All this, in the
light of our present knowledge, is too obvious to us to admit of
discussion. But it seems to me nothing less than pathetic to see how in
the teeth of the obsession as to continental extension, Darwin fought
single-handed for what we now know to be the truth.
Guppy's heart failed him when he had to deal with the isolated case of
Agathis which alone seemed inexplicable by known means of transport. But
when we remember that it is a relic of the pre-Angiospermous flora, and is
of Araucarian ancestry, it cannot be said that the impossibility, in so
prolonged a history, of the bodily transference of cone-bearing branches or
even of trees, compels us as a last resort to fall back on continental
extension to account for its existing distribution.
When Darwin was in the Galapagos Archipelago, he tells us that he fancied
himself "brought near to the very act of creation." He saw how new species
might arise from a common stock. Krakatau shows us an earlier stage and
how by simple agencies, continually at work, that stock might be supplied.
It also shows us how the mixed and casual elements of a new colony enter
into competition for the ground and become mutually adjusted. The study of
Plant Distribution from a Darwinian standpoint has opened up a new field of
research in Ecology. The means of transport supply the materials for a
flora, but their ultimate fate depends on their equipment for the "struggle
for existence." The whole subject can no longer be regarded as a mere
statistical inquiry which has seemed doubtless to many of somewhat arid
interest. The fate of every element of the earth's vegetation has sooner
or later depended on its ability to travel and to hold its own under new
conditions. And the means by which it has secured success is an each case
a biological problem which demands and will reward the most attentive
study. This is the lesson which Darwin has bequeathed to us. It is summed
up in the concluding paragraph of the "Origin" ("Origin of Species" (6th
edition), page 429.):--"It is interesting to contemplate a tangled bank,
clothed with many plants of many kinds, with birds singing on the bushes,
with various insects flitting about, and with worms crawling through the
damp earth, and to reflect that these elaborately constructed forms, so
different from each other, and dependent upon each other in so complex a
manner, have all been produced by laws acting around us."
XVII. GEOGRAPHICAL DISTRIBUTION OF ANIMALS.
By HANS GADOW, M.A., Ph.D., F.R.S.
Strickland Curator and Lecturer on Zoology in the University of Cambridge.
The first general ideas about geographical distribution may be found in
some of the brilliant speculations contained in Buffon's "Histoire
Naturelle". The first special treatise on the subject was however written
in 1777 by E.A.W. Zimmermann, Professor of Natural Science at Brunswick,
whose large volume, "Specimen Zoologiae Geographicae Quadrupedum"..., deals
in a statistical way with the mammals; important features of the large
accompanying map of the world are the ranges of mountains and the names of
hundreds of genera indicating their geographical range. In a second work
he laid special stress on domesticated animals with reference to the
spreading of the various races of Mankind.
In the following year appeared the "Philosophia Entomologica" by J.C.
Fabricius, who was the first to divide the world into eight regions. In
1803 G.R. Treviranus ("Biologie oder Philosophie der lebenden Natur", Vol.
II. Gottingen, 1803.) devoted a long chapter of his great work on
"Biologie" to a philosophical and coherent treatment of the distribution of
the whole animal kingdom. Remarkable progress was made in 1810 by F.
Tiedemann ("Anatomie und Naturgeschichte der Vogel". Heidelberg, 1810.) of
Heidelberg. Few, if any, of the many subsequent Ornithologists seem to
have appreciated, or known of, the ingenious way in which Tiedemann
marshalled his statistics in order to arrive at general conclusions. There
are, for instance, long lists of birds arranged in accordance with their
occurrence in one or more continents: by correlating the distribution of
the birds with their food he concludes "that the countries of the East
Indian flora have no vegetable feeders in common with America," and "that
it is probably due to the great peculiarity of the African flora that
Africa has few phytophagous kinds in common with other countries, whilst
zoophagous birds have a far more independent, often cosmopolitan,
distribution." There are also remarkable chapters on the influence of
environment, distribution, and migration, upon the structure of the Birds!
In short, this anatomist dealt with some of the fundamental causes of
distribution.
Whilst Tiedemann restricted himself to Birds, A. Desmoulins in 1822 wrote a
short but most suggestive paper on the Vertebrata, omitting the birds; he
combated the view recently proposed by the entomologist Latreille that
temperature was the main factor in distribution. Some of his ten main
conclusions show a peculiar mixture of evolutionary ideas coupled with the
conception of the stability of species: whilst each species must have
started from but one creative centre, there may be several "analogous
centres of creation" so far as genera and families are concerned.
Countries with different faunas, but lying within the same climatic zones,
are proof of the effective and permanent existence of barriers preventing
an exchange between the original creative centres.
The first book dealing with the "geography and classification" of the whole
animal kingdom was written by W. Swainson ("A Treatise on the Geography and
Classification of Animals", Lardner's "Cabinet Cyclopaedia" London, 1835.)
in 1835. He saw in the five races of Man the clue to the mapping of the
world into as many "true zoological divisions," and he reconciled the five
continents with his mystical quinary circles.
Lyell's "Principles of Geology" should have marked a new epoch, since in
his "Elements" he treats of the past history of the globe and the
distribution of animals in time, and in his "Principles" of their
distribution in space in connection with the actual changes undergone by
the surface of the world. But as the sub-title of his great work "Modern
changes of the Earth and its inhabitants" indicates, he restricted himself
to comparatively minor changes, and, emphatically believing in the
permanency of the great oceans, his numerous and careful interpretations of
the effect of the geological changes upon the dispersal of animals did
after all advance the problem but little.
Hitherto the marine faunas had been neglected. This was remedied by E.
Forbes, who established nine homozoic zones, based mainly on the study of
the mollusca, the determining factors being to a great extent the isotherms
of the sea, whilst the 25 provinces were given by the configuration of the
land. He was followed by J.D. Dana, who, taking principally the Crustacea
as a basis, and as leading factors the mean temperatures of the coldest and
of the warmest months, established five latitudinal zones. By using these
as divisors into an American, Afro-European, Oriental, Arctic and Antarctic
realm, most of which were limited by an eastern and western land-boundary,
he arrived at about threescore provinces.
In 1853 appeared L.K. Schmarda's ("Die geographische Verbreitung der
Thiere", Wien, 1853.) two volumes, embracing the whole subject. Various
centres of creation being, according to him, still traceable, he formed the
hypothesis that these centres were originally islands, which later became
enlarged and joined together to form the great continents, so that the
original faunas could overlap and mix whilst still remaining pure at their
respective centres. After devoting many chapters to the possible physical
causes and modes of dispersal, he divided the land into 21 realms which he
shortly characterises, e.g. Australia as the only country inhabited by
marsupials, monotremes and meliphagous birds. Ten main marine divisions
were diagnosed in a similar way. Although some of these realms were not
badly selected from the point of view of being applicable to more than one
class of animals, they were obviously too numerous for general purposes,
and this drawback was overcome, in 1857, by P.L. Sclater. ("On the general
Geographical Distribution of the members of the class Aves", "Proc. Linn.
Soc." (Zoology II. 1858, pages 130-145.) Starting with the idea, that
"each species must have been created within and over the geographical area,
which it now occupies," he concluded "that the most natural primary
ontological divisions of the Earth's surface" were those six regions, which
since their adoption by Wallace in his epoch-making work, have become
classical. Broadly speaking, these six regions are equivalent to the great
masses of land; they are convenient terms for geographical facts,
especially since the Palaearctic region expresses the unity of Europe with
the bulk of Asia. Sclater further brigaded the regions of the Old World as
Palaeogaea and the two Americas as Neogaea, a fundamental mistake,
justifiable to a certain extent only since he based his regions mainly upon
the present distribution of the Passerine birds.
Unfortunately these six regions are not of equal value. The Indian
countries and the Ethiopian region (Africa south of the Sahara) are
obviously nothing but the tropical, southern continuations or appendages of
one greater complex. Further, the great eastern mass of land is so
intimately connected with North America that this continent has much more
in common with Europe and Asia than with South America. Therefore, instead
of dividing the world longitudinally as Sclater had done, Huxley, in 1868
("On the classification and distribution of the Alectoromorphae and
Heteromorphae", "Proc. Zool. Soc." 1868, page 294.), gave weighty reasons
for dividing it transversely. Accordingly he established two primary
divisions, Arctogaea or the North world in a wider sense, comprising
Sclater's Indian, African, Palaearctic and Neartic regions; and Notogaea,
the Southern world, which he divided into (1) Austro-Columbia (an
unfortunate substitute for the neotropical region), (2) Australasia, and
(3) New Zealand, the number of big regions thus being reduced to three but
for the separation of New Zealand upon rather negative characters. Sclater
was the first to accept these four great regions and showed, in 1874 ("The
geographical distribution of Mammals", "Manchester Science Lectures",
1874.), that they were well borne out by the present distribution of the
Mammals.
Although applicable to various other groups of animals, for instance to the
tailless Amphibia and to Birds (Huxley himself had been led to found his
two fundamental divisions on the distribution of the Gallinaceous birds),
the combination of South America with Australia was gradually found to be
too sweeping a measure. The obvious and satisfactory solution was provided
by W.T. Blanford (Anniversary address (Geological Society, 1889), "Proc.
Geol. Soc." 1889-90, page 67; "Quart. Journ." XLVI 1890.), who in 1890
recognised three main divisions, namely Australian, South American, and the
rest, for which the already existing terms (although used partly in a new
sense, as proposed by an anonymous writer in "Natural Science", III. page
289) "Notogaea," "Neogaea" and "Arctogaea" have been gladly accepted by a
number of English writers.
After this historical survey of the search for larger and largest or
fundamental centres of animal creation, which resulted in the mapping of
the world into zoological regions and realms of after all doubtful value,
we have to return to the year 1858. The eleventh and twelfth chapters of
"The Origin of Species" (1859), dealing with "Geographical Distribution,"
are based upon a great amount of observation, experiment and reading. As
Darwin's main problem was the origin of species, nature's way of making
species by gradual changes from others previously existing, he had to
dispose of the view, held universally, of the independent creation of each
species and at the same time to insist upon a single centre of creation for
each species; and in order to emphasise his main point, the theory of
descent, he had to disallow convergent, or as they were then called,
analogous forms. To appreciate the difficulty of his position we have to
take the standpoint of fifty years ago, when the immutability of the
species was an axiom and each was supposed to have been created within or
over the geographical area which it now occupies. If he once admitted that
a species could arise from many individuals instead of from one pair, there
was no way of shutting the door against the possibility that these
individuals may have been so numerous that they occupied a very large
district, even so large that it had become as discontinuous as the
distribution of many a species actually is. Such a concession would at
once be taken as an admission of multiple, independent, origin instead of
descent in Darwin's sense.
For the so-called multiple, independently repeated creation of species as
an explanation of their very wide and often quite discontinuous
distribution, he substituted colonisation from the nearest and readiest
source together with subsequent modification and better adaptation to their
new home.
He was the first seriously to call attention to the many accidental means,
"which more properly should be called occasional means of distribution,"
especially to oceanic islands. His specific, even individual, centres of
creation made migrations all the more necessary, but their extent was sadly
baulked by the prevailing dogma of the permanency of the oceans. Any
number of small changes ("many islands having existed as halting places, of
which not a wreck now remains" ("The Origin of Species" (1st edition), page
396.).) were conceded freely, but few, if any, great enough to permit
migration of truly terrestrial creatures. The only means of getting across
the gaps was by the principle of the "flotsam and jetsam," a theory which
Darwin took over from Lyell and further elaborated so as to make it
applicable to many kinds of plants and animals, but sadly deficient, often
grotesque, in the case of most terrestrial creatures.
Another very fertile source was Darwin's strong insistence upon the great
influence which the last glacial epoch must have had upon the distribution
of animals and plants. Why was the migration of northern creatures
southwards of far-reaching and most significant importance? More
northerners have established themselves in southern lands than vice versa,
because there is such a great mass of land in the north and greater
continents imply greater intensity of selection. "The productions of real
islands have everywhere largely yielded to continental forms." (Ibid. page
380.)..."The Alpine forms have almost everywhere largely yielded to the
more dominant forms generated in the larger areas and more efficient
workshops of the North."
Let us now pass in rapid survey the influence of the publication of "The
Origin of Species" upon the study of Geographical Distribution in its wider
sense.
Hitherto the following thought ran through the minds of most writers:
Wherever we examine two or more widely separated countries their respective
faunas are very different, but where two faunas can come into contact with
each other, they intermingle. Consequently these faunas represent centres
of creation, whence the component creatures have spread peripherally so far
as existing boundaries allowed them to do so. This is of course the
fundamental idea of "regions." There is not one of the numerous writers
who considered the possibility that these intermediate belts might
represent not a mixture of species but transitional forms, the result of
changes undergone by the most peripheral migrants in adaptation to their
new surroundings. The usual standpoint was also that of Pucheran ("Note
sur l'equateur zoologique", "Rev. et Mag. de Zoologie", 1855; also several
other papers, ibid. 1865, 1866, and 1867.) in 1855. But what a change
within the next ten years! Pucheran explains the agreement in coloration
between the desert and its fauna as "une harmonie post-etablie"; the
Sahara, formerly a marine basin, was peopled by immigrants from the
neighbouring countries, and these new animals adapted themselves to the new
environment. He also discusses, among other similar questions, the Isthmus
of Panama with regard to its having once been a strait. From the same
author may be quoted the following passage as a strong proof of the new
influence: "By the radiation of the contemporaneous faunas, each from one
centre, whence as the various parts of the world successively were formed
and became habitable, they spread and became modified according to the
local physical conditions."
The "multiple" origin of each species as advocated by Sclater and Murray,
although giving the species a broader basis, suffered from the same
difficulties. There was only one alternative to the old orthodox view of
independent creation, namely the bold acceptance of land-connections to an
extent for which geological and palaeontological science was not yet ripe.
Those who shrank from either view, gave up the problem as mysterious and
beyond the human intellect. This was the expressed opinion of men like
Swainson, Lyell and Humboldt. Only Darwin had the courage to say that the
problem was not insoluble. If we admit "that in the long course of time
the individuals of the same species, and likewise of allied species, have
proceeded from some one source; then I think all the grand leading facts of
geographical distribution are explicable on the theory of
migration...together with subsequent modification and the multiplication of
new forms." We can thus understand how it is that in some countries the
inhabitants "are linked to the extinct beings which formerly inhabited the
same continent." We can see why two areas, having nearly the same physical
conditions, should often be inhabited by very different forms of
life,...and "we can see why in two areas, however distant from each other,
there should be a correlation, in the presence of identical species...and
of distinct but representative species." ("The Origin of Species" (1st
edition), pages 408, 409.)
Darwin's reluctance to assume great geological changes, such as a land-
connection of Europe with North America, is easily explained by the fact
that he restricted himself to the distribution of the present and
comparatively recent species. "I do not believe that it will ever be
proved that within the recent period continents which are now quite
separate, have been continuously, or almost continuously, united with each
other, and with the many existing oceanic islands." (Ibid. page 357.)
Again, "believing...that our continents have long remained in nearly the
same relative position, though subjected to large, but partial oscillations
of level," that means to say within the period of existing species, or
"within the recent period." (Ibid. page. 370.) The difficulty was to a
great extent one of his own making. Whilst almost everybody else believed
in the immutability of the species, which implies an enormous age,
logically since the dawn of creation, to him the actually existing species
as the latest results of evolution, were necessarily something very new, so
young that only the very latest of the geological epochs could have
affected them. It has since come to our knowledge that a great number of
terrestrial "recent" species, even those of the higher classes of
Vertebrates, date much farther back than had been thought possible. Many
of them reach well into the Miocene, a time since which the world seems to
have assumed the main outlines of the present continents.
In the year 1866 appeared A. Murray's work on the "Geographical
Distribution of Mammals", a book which has perhaps received less
recognition than it deserves. His treatment of the general introductory
questions marks a considerable advance of our problem, although, and partly
because, he did not entirely agree with Darwin's views as laid down in the
first edition of "The Origin of Species", which after all was the great
impulse given to Murray's work. Like Forbes he did not shrink from
assuming enormous changes in the configuration of the continents and oceans
because the theory of descent, with its necessary postulate of great
migrations, required them. He stated, for instance, "that a Miocene
Atlantis sufficiently explains the common distribution of animals and
plants in Europe and America up to the glacial epoch." And next he
considers how, and by what changes, the rehabilitation and distribution of
these lands themselves were effected subsequent to that period. Further,
he deserves credit for having cleared up a misunderstanding of the idea of
specific centres of creation. Whilst for instance Schmarda assumed without
hesitation that the same species, if occurring at places separated by great
distances, or apparently insurmountable barriers, had been there created
independently (multiple centres), Lyell and Darwin held that each species
had only one single centre, and with this view most of us agree, but their
starting point was to them represented by one individual, or rather one
single pair. According to Murray, on the other hand, this centre of a
species is formed by all the individuals of a species, all of which equally
undergo those changes which new conditions may impose upon them. In this
respect a new species has a multiple origin, but this in a sense very
different from that which was upheld by L. Agassiz. As Murray himself puts
it: "To my multiple origin, communication and direct derivation is
essential. The species is compounded of many influences brought together
through many individuals, and distilled by Nature into one species; and,
being once established it may roam and spread wherever it finds the
conditions of life not materially different from those of its original
centre." (Murray, "The Geographical Distribution of Mammals", page 14.
London, 1866.) This declaration fairly agrees with more modern views, and
it must be borne in mind that the application of the single-centre
principle to the genera, families and larger groups in the search for
descent inevitably leads to one creative centre for the whole animal
kingdom, a condition as unwarrantable as the myth of Adam and Eve being the
first representatives of Mankind.
It looks as if it had required almost ten years for "The Origin of Species"
to show its full effect, since the year 1868 marks the publication of
Haeckel's "Naturliche Schoepfungsgeschichte" in addition to other great
works. The terms "Oecology" (the relation of organisms to their
environment) and "Chorology" (their distribution in space) had been given
us in his "Generelle Morphologie" in 1866. The fourteenth chapter of the
"History of Creation" is devoted to the distribution of organisms, their
chorology, with the emphatic assertion that "not until Darwin can chorology
be spoken of as a separate science, since he supplied the acting causes for
the elucidation of the hitherto accumulated mass of facts." A map (a
"hypothetical sketch") shows the monophyletic origin and the routes of
distribution of Man.
Natural Selection may be all-mighty, all-sufficient, but it requires time,
so much that the countless aeons required for the evolution of the present
fauna were soon felt to be one of the most serious drawbacks of the theory.
Therefore every help to ease and shorten this process should have been
welcomed. In 1868 M. Wagner (The first to formulate clearly the
fundamental idea of a theory of migration and its importance in the origin
of new species was L. von Buch, who in his "Physikalische Beschreibung der
Canarischen Inseln", written in 1825, wrote as follows: "Upon the
continents the individuals of the genera by spreading far, form, through
differences of the locality, food and soil, varieties which finally become
constant as new species, since owing to the distances they could never be
crossed with other varieties and thus be brought back to the main type.
Next they may again, perhaps upon different roads, return to the old home
where they find the old type likewise changed, both having become so
different that they can interbreed no longer. Not so upon islands, where
the individuals shut up in narrow valleys or within narrow districts, can
always meet one another and thereby destroy every new attempt towards the
fixing of a new variety." Clearly von Buch explains here why island types
remain fixed, and why these types themselves have become so different from
their continental congeners.--Actually von Buch is aware of a most
important point, the difference in the process of development which exists
between a new species b, which is the result of an ancestral species a
having itself changed into b and thereby vanished itself, and a new species
c which arose through separation out of the same ancestral a, which itself
persists as such unaltered. Von Buch's prophetic view seems to have
escaped Lyell's and even Wagner's notice.) came to the rescue with his
"Darwin'sche Theorie und das Migrations-Gesetz der Organismen". (Leipzig,
1868.) He shows that migration, i.e. change of locality, implies new
environmental conditions (never mind whether these be new stimuli to
variation, or only acting as their selectors or censors), and moreover
secures separation from the original stock and thus eliminates or lessens
the reactionary dangers of panmixia. Darwin accepted Wagner's theory as
"advantageous." Through the heated polemics of the more ardent
selectionists Wagner's theory came to grow into an alternative instead of a
help to the theory of selectional evolution. Separation is now rightly
considered a most important factor by modern students of geographical
distribution.
For the same year, 1868, we have to mention Huxley, whose Arctogaea and
Notogaea are nothing less than the reconstructed main masses of land of the
Mesozoic period. Beyond doubt the configuration of land at that remote
period has left recognisable traces in the present continents, but whether
they can account for the distribution of such a much later group as the
Gallinaceous birds is more than questionable. In any case he took for his
text a large natural group of birds, cosmopolitan as a whole, but with a
striking distribution. The Peristeropodes, or pigeon-footed division, are
restricted to the Australian and Neotropical regions, in distinction to the
Alectoropodes (with the hallux inserted at a level above the front toes)
which inhabit the whole of the Arctogaea, only a few members having spread
into the South World. Further, as Asia alone has its Pheasants and allies,
so is Africa characterised by its Guinea-fowls and relations, America has
the Turkey as an endemic genus, and the Grouse tribe in a wider sense has
its centre in the holarctic region: a splendid object lesson of descent,
world-wide spreading and subsequent differentiation. Huxley, by the way,
was the first--at least in private talk--to state that it will be for the
morphologist, the well-trained anatomist, to give the casting vote in
questions of geographical distribution, since he alone can determine
whether we have to deal with homologous, or analogous, convergent,
representative forms.
It seems late to introduce Wallace's name in 1876, the year of the
publication of his standard work. ("The Geographical Distribution of
Animals", 2 vols. London, 1876.) We cannot do better than quote the
author's own words, expressing the hope that his "book should bear a
similar relation to the eleventh and twelfth chapters of the "Origin of
Species" as Darwin's "Animals and Plants under Domestication" does to the
first chapter of that work," and to add that he has amply succeeded.
Pleading for a few primary centres he accepts Sclater's six regions and
does not follow Huxley's courageous changes which Sclater himself had
accepted in 1874. Holding the view of the permanence of the oceans he
accounts for the colonisation of outlying islands by further elaborating
the views of Lyell and Darwin, especially in his fascinating "Island Life",
with remarkable chapters on the Ice Age, Climate and Time and other
fundamental factors. His method of arriving at the degree of relationship
of the faunas of the various regions is eminently statistical. Long lists
of genera determine by their numbers the affinity and hence the source of
colonisation. In order to make sure of his material he performed the
laborious task of evolving a new classification of the host of Passerine
birds. This statistical method has been followed by many authors, who,
relying more upon quantity than quality, have obscured the fact that the
key to the present distribution lies in the past changes of the earth's
surface. However, with Wallace begins the modern study of the geographical
distribution of animals and the sudden interest taken in this subject by an
ever widening circle of enthusiasts far beyond the professional
brotherhood.
A considerable literature has since grown up, almost bewildering in its
range, diversity of aims and style of procedure. It is a chaos, with many
paths leading into the maze, but as yet very few take us to a position
commanding a view of the whole intricate terrain with its impenetrable
tangle and pitfalls.
One line of research, not initiated but greatly influenced by Wallace's
works, became so prominent as to almost constitute a period which may be
characterised as that of the search by specialists for either the
justification or the amending of his regions. As class after class of
animals was brought up to reveal the secret of the true regions, some
authors saw in their different results nothing but the faultiness of
previously established regions; others looked upon eventual agreements as
their final corroboration, especially when for instance such diverse groups
as mammals and scorpions could, with some ingenuity, be made to harmonise.
But the obvious result of all these efforts was the growing knowledge that
almost every class seemed to follow principles of its own. The regions
tallied neither in extent nor in numbers, although most of them gravitated
more and more towards three centres, namely Australia, South America and
the rest of the world. Still zoologists persisted in the search, and the
various modes and capabilities of dispersal of the respective groups were
thought sufficient explanation of the divergent results in trying to bring
the mapping of the world under one scheme.
Contemporary literature is full of devices for the mechanical dispersal of
animals. Marine currents, warm and cold, were favoured all the more since
they showed the probable original homes of the creatures in question. If
these could not stand sea-water, they floated upon logs or icebergs, or
they were blown across by storms; fishes were lifted over barriers by
waterspouts, and there is on record even an hypothetical land tortoise,
full of eggs, which colonised an oceanic island after a perilous sea voyage
upon a tree trunk. Accidents will happen, and beyond doubt many freaks of
discontinuous distribution have to be accounted for by some such means.
But whilst sufficient for the scanty settlers of true oceanic islands, they
cannot be held seriously to account for the rich fauna of a large
continent, over which palaeontology shows us that the immigrants have
passed like waves. It should also be borne in mind that there is a great
difference between flotsam and jetsam. A current is an extension of the
same medium and the animals in it may suffer no change during even a long
voyage, since they may be brought from one litoral to another where they
will still be in the same or but slightly altered environment. But the
jetsam is in the position of a passenger who has been carried off by the
wrong train. Almost every year some American land birds arrive at our
western coasts and none of them have gained a permanent footing although
such visits must have taken place since prehistoric times. It was
therefore argued that only those groups of animals should be used for
locating and defining regions which were absolutely bound to the soil.
This method likewise gave results not reconcilable with each other, even
when the distribution of fossils was taken into account, but it pointed to
the absolute necessity of searching for former land-connections regardless
of their extent and the present depths to which they may have sunk.
That the key to the present distribution lies in the past had been felt
long ago, but at last it was appreciated that the various classes of
animals and plants have appeared in successive geological epochs and also
at many places remote from each other. The key to the distribution of any
group lies in the configuration of land and water of that epoch in which it
made its first appearance. Although this sounds like a platitude, it has
frequently been ignored. If, for argument's sake, Amphibia were evolved
somewhere upon the great southern land-mass of Carboniferous times
(supposed by some to have stretched from South America across Africa to
Australia), the distribution of this developing class must have proceeded
upon lines altogether different from that of the mammals which dated
perhaps from lower Triassic times, when the old south continental belt was
already broken up. The broad lines of this distribution could never
coincide with that of the other, older class, no matter whether the
original mammalian centre was in the Afro-Indian, Australian, or Brazilian
portion. If all the various groups of animals had come into existence at
the same time and at the same place, then it would be possible, with
sufficient geological data, to construct a map showing the generalised
results applicable to the whole animal kingdom. But the premises are
wrong. Whatever regions we may seek to establish applicable to all
classes, we are necessarily mixing up several principles, namely
geological, historical, i.e. evolutionary, with present day statistical
facts. We might as well attempt one compound picture representing a
chick's growth into an adult bird and a child's growth into manhood.
In short there are no general regions, not even for each class separately,
unless this class be one which is confined to a comparatively short
geological period. Most of the great classes have far too long a history
and have evolved many successive main groups. Let us take the mammals.
Marsupials live now in Australia and in both Americas, because they already
existed in Mesozoic times; Ungulata existed at one time or other all over
the world except in Australia, because they are post-Cretaceous;
Insectivores, although as old as any Placentalia, are cosmopolitan
excepting South America and Australia; Stags and Bears, as examples of
comparatively recent Arctogaeans, are found everywhere with the exception
of Ethiopia and Australia. Each of these groups teaches a valuable
historical lesson, but when these are combined into the establishment of a
few mammalian "realms," they mean nothing but statistical majorities. If
there is one at all, Australia is such a realm backed against the rest of
the world, but as certainly it is not a mammalian creative centre!
Well then, if the idea of generally applicable regions is a mare's nest, as
was the search for the Holy Grail, what is the object of the study of
geographical distribution? It is nothing less than the history of the
evolution of life in space and time in the widest sense. The attempt to
account for the present distribution of any group of organisms involves the
aid of every branch of science. It bids fair to become a history of the
world. It started in a mild, statistical way, restricting itself to the
present fauna and flora and to the present configuration of land and water.
Next came Oceanography concerned with the depths of the seas, their
currents and temperatures; then enquiries into climatic changes,
culminating in irreconcilable astronomical hypotheses as to glacial epochs;
theories about changes of the level of the seas, mainly from the point of
view of the physicist and astronomer. Then came more and more to the front
the importance of the geological record, hand in hand with the
palaeontological data and the search for the natural affinities, the
genetic system of the organisms. Now and then it almost seems as if the
biologists had done their share by supplying the problems and that the
physicists and geologists would settle them, but in reality it is not so.
The biologists not only set the problems, they alone can check the offered
solutions. The mere fact of palms having flourished in Miocene Spitzbergen
led to an hypothetical shifting of the axis of the world rather than to the
assumption, by way of explanation, that the palms themselves might have
changed their nature. One of the most valuable aids in geological
research, often the only means for reconstructing the face of the earth in
by-gone periods, is afforded by fossils, but only the morphologist can
pronounce as to their trustworthiness as witnesses, because of the danger
of mistaking analogous for homologous forms. This difficulty applies
equally to living groups, and it is so important that a few instances may
not be amiss.
There is undeniable similarity between the faunas of Madagascar and South
America. This was supported by the Centetidae and Dendrobatidae, two
entire "families," as also by other facts. The value of the Insectivores,
Solenodon in Cuba, Centetes in Madagascar, has been much lessened by their
recognition as an extremely ancient group and as a case of convergence, but
if they are no longer put into the same family, this amendment is really to
a great extent due to their widely discontinuous distribution. The only
systematic difference of the Dendrobatidae from the Ranidae is the absence
of teeth, morphologically a very unimportant character, and it is now
agreed, on the strength of their distribution, that these little arboreal,
conspicuously coloured frogs, Dendrobates in South America, Mantella in
Madagascar, do not form a natural group, although a third genus,
Cardioglossa in West Africa, seems also to belong to them. If these
creatures lived all on the same continent, we should unhesitatingly look
upon them as forming a well-defined, natural little group. On the other
hand the Aglossa, with their three very divergent genera, namely Pipa in
South America, Xenopus and Hymenochirus in Africa, are so well
characterised as one ancient group that we use their distribution
unhesitatingly as a hint of a former connection between the two continents.
We are indeed arguing in vicious circles. The Ratitae as such are
absolutely worthless since they are a most heterogeneous assembly, and
there are untold groups, of the artificiality of which many a zoo-
geographer had not the slightest suspicion when he took his statistical
material, the genera and families, from some systematic catalogues or
similar lists. A lamentable instance is that of certain flightless Rails,
recently extinct or sub-fossil, on the isalnds of Mauritius, Rodriguez and
Chatham. Being flightless they have been used in support of a former huge
Antarctic continent, instead of ruling them out of court as Rails which,
each in its island, have lost the power of flight, a process which must
have taken place so recently that it is difficult, upon morphological
grounds, to justify their separation into Aphanapteryx in Mauritius,
Erythromachus in Rodriguez and Diaphorapteryx on Chatham Island.
Morphologically they may well form but one genus, since they have sprung
from the same stock and have developed upon the same lines; they are
therefore monogenetic: but since we know that they have become what they
are independently of each other (now unlike any other Rails), they are
polygenetic and therefore could not form one genus in the old Darwinian
sense. Further, they are not a case of convergence, since their ancestry
is not divergent but leads into the same stratum.
THE RECONSTRUCTION OF THE GEOGRAPHY OF SUCCESSIVE EPOCHS.
A promising method is the study by the specialist of a large, widely
distributed group of animals from an evolutionary point of view. Good
examples of this method are afforded by A.E. Ortmann's ("The geographical
distribution of Freshwater Decapods and its bearing upon ancient
geography", "Proc. Amer. Phil. Soc." Vol. 41, 1902.) exhaustive paper and
by A.W. Grabau's "Phylogeny of Fusus and its Allies" ("Smithsonian Misc.
Coll." 44, 1904.) After many important groups of animals have been treated
in this way--as yet sparingly attempted--the results as to hypothetical
land-connections etc. are sure to be corrective and supplementary, and
their problems will be solved, since they are not imaginary.
The same problems are attacked, in the reverse way, by starting with the
whole fauna of a country and thence, so to speak, letting the research
radiate. Some groups will be considered as autochthonous, others as
immigrants, and the directions followed by them will be inquired into; the
search may lead far and in various directions, and by comparison of
results, by making compound maps, certain routes will assume definite
shape, and if they lead across straits and seas they are warrants to search
for land-connections in the past. (A fair sample of this method is C.H.
Eigenmann's "The Freshwater Fishes of South and Middle America", "Popular
Science Monthly", Vol. 68, 1906.) There are now not a few maps purporting
to show the outlines of land and water at various epochs. Many of these
attempts do not tally with each other, owing to the lamentable deficiencies
of geological and fossil data, but the bolder the hypothetical outlines are
drawn, the better, and this is preferable to the insertion of bays and
similar detail which give such maps a fallacious look of certainty where
none exists. Moreover it must be borne in mind that, when we draw a broad
continental belt across an ocean, this belt need never have existed in its
entirety at any one time. The features of dispersal, intended to be
explained by it, would be accomplished just as well by an unknown number of
islands which have joined into larger complexes while elsewhere they
subsided again: like pontoon-bridges which may be opened anywhere, or like
a series of superimposed dissolving views of land and sea-scapes. Hence
the reconstructed maps of Europe, the only continent tolerably known, show
a considerable number of islands in puzzling changes, while elsewhere, e.g.
in Asia, we have to be satisfied with sweeping generalisations.
At present about half-a-dozen big connections are engaging our attention,
leaving as comparatively settled the extent and the duration of such minor
"bridges" as that between Africa and Madagascar, Tasmania and Australia,
the Antilles and Central America, Europe and North Africa. (Not a few of
those who are fascinated by, and satisfied with, the statistical aspect of
distribution still have a strong dislike to the use of "bridges" if these
lead over deep seas, and they get over present discontinuous occurrences by
a former "universal or sub-universal distribution" of their groups. This
is indeed an easy method of cutting the knot, but in reality they shunt the
question only a stage or two back, never troubling to explain how their
groups managed to attain to that sub-universal range; or do they still
suppose that the whole world was originally one paradise where everything
lived side by side, until sin and strife and glacial epochs left nothing
but scattered survivors?
The permanence of the great ocean-basins had become a dogma since it was
found that a universal elevation of the land to the extent of 100 fathoms
would produce but little changes, and when it was shown that even the 1000
fathom-line followed the great masses of land rather closely, and still
leaving the great basins (although transgression of the sea to the same
extent would change the map of the world beyond recognition), by general
consent one mile was allowed as the utmost speculative limit of subsidence.
Naturally two or three miles, the average depth of the oceans, seems
enormous, and yet such a difference in level is as nothing in comparison
with the size of the Earth. On a clay model globe ten feet in diameter an
ocean bed three miles deep would scarcely be detected, and the highest
mountains would be smaller than the unavoidable grains in the glazed
surface of our model. There are but few countries which have not be
submerged at some time or other.)
CONNECTION OF SOUTH EASTERN ASIA WITH AUSTRALIA. Neumayr's Sino-Australian
continent during mid-Mesozoic times was probably a much changing
Archipelago, with final separations subsequent to the Cretaceous period.
Henceforth Australasia was left to its own fate, but for a possible
connection with the antarctic continent.
AFRICA, MADAGASCAR, INDIA. The "Lemuria" of Sclater and Haeckel cannot
have been more than a broad bridge in Jurassic times; whether it was ever
available for the Lemurs themselves must depend upon the time of its
duration, the more recent the better, but it is difficult to show that it
lasted into the Miocene.
AFRICA AND SOUTH AMERICA. Since the opposite coasts show an entire absence
of marine fossils and deposits during the Mesozoic period, whilst further
north and south such are known to exist and are mostly identical on either
side, Neumayr suggested the existence of a great Afro-Son American mass of
land during the Jurassic epoch. Such land is almost a necessity and is
supported by many facts; it would easily explain the distribution of
numerous groups of terrestrial creatures. Moreover to the north of this
hypothetical land, somewhere across from the Antilles and Guiana to North
Africa and South Western Europe, existed an almost identical fauna of
Corals and Molluscs, indicating either a coast-line or a series of islands
interrupted by shallow seas, just as one would expect if, and when, a
Brazil-Ethiopian mass of land were breaking up. Lastly from Central
America to the Mediterranean stretches one of the Tertiary tectonic lines
of the geologists. Here also the great question is how long this continent
lasted. Apparently the South Atlantic began to encroach from the south so
that by the later Cretaceous epoch the land was reduced to a comparatively
narrow Brazil-West Africa, remnants of which persisted certainly into the
early Tertiary, until the South Atlantic joined across the equator with the
Atlantic portion of the "Thetys," leaving what remained of South America
isolated from the rest of the world.
ANTARCTIC CONNECTIONS. Patagonia and Argentina seem to have joined
Antartica during the Cretaceous epoch, and this South Georgian bridge had
broken down again by mid-Tertiary times when South America became
consolidated. The Antarctic continent, presuming that it existed, seems
also to have been joined, by way of Tasmania, with Australia, also during
the Cretaceous epoch, and it is assumed that the great Australia-Antarctic-
Patagonian land was severed first to the south of Tasmania and then at the
South Georgian bridge. No connection, and this is important, is indicated
between Antarctica and either Africa or Madagascar.
So far we have followed what may be called the vicissitudes of the great
Permo-Carboniferous Gondwana land in its fullest imaginary extent, an
enormous equatorial and south temperate belt from South America to Africa,
South India and Australia, which seems to have provided the foundation of
the present Southern continents, two of which temporarily joined
Antarctica, of which however we know nothing except that it exists now.
Let us next consider the Arctic and periarctic lands. Unfortunately very
little is known about the region within the arctic circle. If it was all
land, or more likely great changing archipelagoes, faunistic exchange
between North America, Europe and Siberia would present no difficulties,
but there is one connection which engages much attention, namely a land
where now lies the North temperate and Northern part of the Atlantic ocean.
How far south did it ever extend and what is the latest date of a direct
practicable communication, say from North Western Europe to Greenland?
Connections, perhaps often interrupted, e.g. between Greenland and
Labrador, at another time between Greenland and Scandinavia, seem to have
existed at least since the Permo-Carboniferous epoch. If they existed also
in late Cretaceous and in Tertiary times, they would of course easily
explain exchanges which we know to have repeatedly taken place between
America and Europe, but they are not proved thereby, since most of these
exchanges can almost as easily have occurred across the polar regions, and
others still more easily by repeated junction of Siberia with Alaska.
Let us now describe a hypothetical case based on the supposition of
connecting bridges. Not to work in a circle, we select an important group
which has not served as a basis for the reconstruction of bridges; and it
must be a group which we feel justified in assuming to be old enough to
have availed itself of ancient land-connections.
The occurrence of one species of Peripatus in the whole of Australia,
Tasmania and New Zealand (the latter being joined to Australia by way of
New Britain in Cretaceous times but not later) puts the genus back into
this epoch, no unsatisfactory assumption to the morphologist. The apparent
absence of Peripatus in Madagascar indicates that it did not come from the
east into Africa, that it was neither Afro-Indian, nor Afro-Australian; nor
can it have started in South America. We therefore assume as its creative
centre Australia or Malaya in the Cretaceous epoch, whence its occurrence
in Sumatra, Malay Peninsula, New Britain, New Zealand and Australia is
easily explained. Then extension across Antarctica to Patagonia and Chile,
whence it could spread into the rest of South America as this became
consolidated in early Tertiary times. For getting to the Antilles and into
Mexico it would have to wait until the Miocene, but long before that time
it could arrive in Africa, there surviving as a Congolese and a Cape
species. This story is unsupported by a single fossil. Peripatus may have
been "sub-universal" all over greater Gondwana land in Carboniferous times,
and then its absence from Madagascar would be difficult to explain, but the
migrations suggested above amount to little considering that the distance
from Tasmania to South America could be covered in far less time than that
represented by the whole of the Eocene epoch alone.
There is yet another field, essentially the domain of geographical
distribution, the cultivation of which promises fair to throw much light
upon Nature's way of making species. This is the study of the organisms
with regard to their environment. Instead of revealing pedigrees or of
showing how and when the creatures got to a certain locality, it
investigates how they behaved to meet the ever changing conditions of their
habitats. There is a facies, characteristic of, and often peculiar to, the
fauna of tropical moist forests, another of deserts, of high mountains, of
underground life and so forth; these same facies are stamped upon whole
associations of animals and plants, although these may be--and in widely
separated countries generally are--drawn from totally different families of
their respective orders. It does not go to the root of the matter to say
that these facies have been brought about by the extermination of all the
others which did not happen to fit into their particular environment. One
might almost say that tropical moist forests must have arboreal frogs and
that these are made out of whatever suitable material happened to be
available; in Australia and South America Hylidae, in Africa Ranidae, since
there Hylas are absent. The deserts must have lizards capable of standing
the glare, the great changes of temperature, of running over or burrowing
into the loose sand. When as in America Iguanids are available, some of
these are thus modified, while in Africa and Asia the Agamids are drawn
upon. Both in the Damara and in the Transcaspian deserts, a Gecko has been
turned into a runner upon sand!
We cannot assume that at various epochs deserts, and at others moist
forests were continuous all over the world. The different facies and
associations were developed at various times and places. Are we to suppose
that, wherever tropical forests came into existence, amongst the stock of
humivagous lizards were always some which presented those nascent
variations which made them keep step with the similarly nascent forests,
the overwhelming rest being eliminated? This principle would imply that
the same stratum of lizards always had variations ready to fit any changed
environment, forests and deserts, rocks and swamps. The study of Ecology
indicates a different procedure, a great, almost boundless plasticity of
the organism, not in the sense of an exuberant moulding force, but of a
readiness to be moulded, and of this the "variations" are the visible
outcome. In most cases identical facies are produced by heterogeneous
convergences and these may seem to be but superficial, affecting only what
some authors are pleased to call the physiological characters; but
environment presumably affects first those parts by which the organism
comes into contact with it most directly, and if the internal structures
remain unchanged, it is not because these are less easily modified but
because they are not directly affected. When they are affected, they too
change deeply enough.
That the plasticity should react so quickly--indeed this very quickness
seems to have initiated our mistaking the variations called forth for
something performed--and to the point, is itself the outcome of the long
training which protoplasm has undergone since its creation.
In Nature's workshop he does not succeed who has ready an arsenal of tools
for every conceivable emergency, but he who can make a tool at the spur of
the moment. The ordeal of the practical test is Charles Darwin's glorious
conception of Natural Selection.
XVIII. DARWIN AND GEOLOGY.
By J.W. JUDD, C.B., LL.D., F.R.S.
(Mr Francis Darwin has related how his father occasionally came up from
Down to spend a few days with his brother Erasmus in London, and, after his
brother's death, with his daughter, Mrs Litchfield. On these occasions, it
was his habit to arrange meetings with Huxley, to talk over zoological
questions, with Hooker, to discuss botanical problems, and with Lyell to
hold conversations on geology. After the death of Lyell, Darwin, knowing
my close intimacy with his friend during his later years, used to ask me to
meet him when he came to town, and "talk geology." The "talks" took place
sometimes at Jermyn Street Museum, at other times in the Royal College of
Science, South Kensington; but more frequently, after having lunch with
him, at his brother's or his daughter's house. On several occasions,
however, I had the pleasure of visiting him at Down. In the postscript of
a letter (of April 15, 1880) arranging one of these visits, he writes:
"Since poor, dear Lyell's death, I rarely have the pleasure of geological
talk with anyone.")
In one of the very interesting conversations which I had with Charles
Darwin during the last seven years of his life, he asked me in a very
pointed manner if I were able to recall the circumstances, accidental or
otherwise, which had led me to devote myself to geological studies. He
informed me that he was making similar inquiries of other friends, and I
gathered from what he said that he contemplated at that time a study of the
causes producing SCIENTIFIC BIAS in individual minds. I have no means of
knowing how far this project ever assumed anything like concrete form, but
certain it is that Darwin himself often indulged in the processes of mental
introspection and analysis; and he has thus fortunately left us--in his
fragments of autobiography and in his correspondence--the materials from
which may be reconstructed a fairly complete history of his own mental
development.
There are two perfectly distinct inquiries which we have to undertake in
connection with the development of Darwin's ideas on the subject of
evolution:
FIRST. How, when, and under what conditions was Darwin led to a conviction
that species were not immutable, but were derived from pre-existing forms?
SECONDLY. By what lines of reasoning and research was he brought to regard
"natural selection" as a vera causa in the process of evolution?
It is the first of these inquiries which specially interests the geologist;
though geology undoubtedly played a part--and by no means an insignificant
part--in respect to the second inquiry.
When, indeed, the history comes to be written of that great revolution of
thought in the nineteenth century, by which the doctrine of evolution, from
being the dream of poets and visionaries, gradually grew to be the accepted
creed of naturalists, the paramount influence exerted by the infant science
of geology--and especially that resulting from the publication of Lyell's
epoch-making work, the "Principles of Geology"--cannot fail to be regarded
as one of the leading factors. Herbert Spencer in his "Autobiography"
bears testimony to the effect produced on his mind by the recently
published "Principles", when, at the age of twenty, he had already begun to
speculate on the subject of evolution (Herbert Spencer's "Autobiography",
London, 1904, Vol. I. pages 175-177.); and Alfred Russel Wallace is
scarcely less emphatic concerning the part played by Lyell's teaching in
his scientific education. (See "My Life; a record of Events and Opinions",
London, 1905, Vol. I. page 355, etc. Also his review of Lyell's
"Principles" in "Quarterly Review" (Vol. 126), 1869, pages 359-394. See
also "The Darwin-Wallace Celebration by the Linnean Society" (1909), page
118.) Huxley wrote in 1887 "I owe more than I can tell to the careful
study of the "Principles of Geology" in my young days." ("Science and
Pseudo Science"; "Collected Essays", London, 1902, Vol. V. page 101.) As
for Charles Darwin, he never tired--either in his published writings, his
private correspondence or his most intimate conversations--of ascribing the
awakening of his enthusiasm and the direction of his energies towards the
elucidation of the problem of development to the "Principles of Geology"
and the personal influence of its author. Huxley has well expressed what
the author of the "Origin of Species" so constantly insisted upon, in the
statements "Darwin's greatest work is the outcome of the unflinching
application to Biology of the leading idea and the method applied in the
"Principles" to Geology ("Proc. Roy. Soc." Vol. XLIV. (1888), page viii.;
"Collected Essays" II. page 268, 1902.), and "Lyell, for others, as for
myself, was the chief agent in smoothing the road for Darwin." ("Life and
Letters of Charles Darwin" II. page 190.)
We propose therefore to consider, first, what Darwin owed to geology and
its cultivators, and in the second place how he was able in the end so
fully to pay a great debt which he never failed to acknowledge. Thanks to
the invaluable materials contained in the "Life and Letters of Charles
Darwin" (3 vols.) published by Mr Francis Darwin in 1887; and to "More
Letters of Charles Darwin" (2 vols.) issued by the same author, in
conjunction with Professor A.C. Seward, in 1903, we are permitted to follow
the various movements in Darwin's mind, and are able to record the story
almost entirely in his own words. (The first of these works is indicated
in the following pages by the letters "L.L."; the second by "M.L.")
From the point of view of the geologist, Darwin's life naturally divides
itself into four periods. In the first, covering twenty-two years, various
influences were at work militating, now for and now against, his adoption
of a geological career; in the second period--the five memorable years of
the voyage of the "Beagle"--the ardent sportsman with some natural-history
tastes, gradually became the most enthusiastic and enlightened of
geologists; in the third period, lasting ten years, the valuable geological
recruit devoted nearly all his energies and time to geological study and
discussion and to preparing for publication the numerous observations made
by him during the voyage; the fourth period, which covers the latter half
of his life, found Darwin gradually drawn more and more from geological to
biological studies, though always retaining the deepest interest in the
progress and fortunes of his "old love." But geologists gladly recognise
the fact that Darwin immeasurably better served their science by this
biological work, than he could possibly have done by confining himself to
purely geological questions.
From his earliest childhood, Darwin was a collector, though up to the time
when, at eight years of age, he went to a preparatory school, seals, franks
and similar trifles appear to have been the only objects of his quest. But
a stone, which one of his schoolfellows at that time gave to him, seems to
have attracted his attention and set him seeking for pebbles and minerals;
as the result of this newly acquired taste, he says (writing in 1838) "I
distinctly recollect the desire I had of being able to know something about
every pebble in front of the hall door--it was my earliest and only
geological aspiration at that time." ("M.L." I. page 3.) He further
suspects that while at Mr Case's school "I do not remember any mental
pursuits except those of collecting stones," etc..."I was born a
naturalist." ("M.L." I. page 4.)
The court-yard in front of the hall door at the Mount House, Darwin's
birthplace and the home of his childhood, is surrounded by beds or
rockeries on which lie a number of pebbles. Some of these pebbles (in
quite recent times as I am informed) have been collected to form a
"cobbled" space in front of the gate in the outer wall, which fronts the
hall door; and a similar "cobbled area," there is reason to believe, may
have existed in Darwin's childhood before the door itself. The pebbles,
which were obtained from a neighbouring gravel-pit, being derived from the
glacial drift, exhibit very striking differences in colour and form. It
was probably this circumstance which awakened in the child his love of
observation and speculation. It is certainly remarkable that "aspirations"
of the kind should have arisen in the mind of a child of 9 or 10!
When he went to Shrewsbury School, he relates "I continued collecting
minerals with much zeal, but quite unscientifically,--all that I cared
about was a new-NAMED mineral, and I hardly attempted to classify them."
("L.L." I. page 34.)
There has stood from very early times in Darwin's native town of
Shrewsbury, a very notable boulder which has probably marked a boundary and
is known as the "Bell-stone"--giving its name to a house and street.
Darwin tells us in his "Autobiography" that while he was at Shrewsbury
School at the age of 13 or 14 "an old Mr Cotton in Shropshire, who knew a
good deal about rocks" pointed out to me "...the 'bell-stone'; he told me
that there was no rock of the same kind nearer than Cumberland or Scotland,
and he solemnly assured me that the world would come to an end before
anyone would be able to explain how this stone came where it now lay"!
Darwin adds "This produced a deep impression on me, and I meditated over
this wonderful stone." ("L.L." I. page 41.)
The "bell-stone" has now, owing to the necessities of building, been
removed a short distance from its original site, and is carefully preserved
within the walls of a bank. It is a block of irregular shape 3 feet long
and 2 feet wide, and about 1 foot thick, weighing probably not less than
one-third of a ton. By the courtesy of the directors of the National
Provincial Bank of England, I have been able to make a minute examination
of it, and Professors Bonney and Watts, with Mr Harker and Mr Fearnsides
have given me their valuable assistance. The rock is a much altered
andesite and was probably derived from the Arenig district in North Wales,
or possibly from a point nearer the Welsh Border. (I am greatly indebted
to the Managers of the Bank at Shrewsbury for kind assistance in the
examination of this interesting memorial: and Mr H.T. Beddoes, the Curator
of the Shrewsbury Museum, has given me some archaeological information
concerning the stone. Mr Richard Cotton was a good local naturalist, a
Fellow both of the Geological and Linnean Societies; and to the officers of
these societies I am indebted for information concerning him. He died in
1839, and although he does not appear to have published any scientific
papers, he did far more for science by influencing the career of the school
boy!" It was of course brought to where Shrewsbury now stands by the
agency of a glacier--as Darwin afterwards learnt.
We can well believe from the perusal of these reminiscences that, at this
time, Darwin's mind was, as he himself says, "prepared for a philosophical
treatment of the subject" of Geology. ("L.L." I. page 41.) When at the
age of 16, however, he was entered as a medical student at Edinburgh
University, he not only did not get any encouragement of his scientific
tastes, but was positively repelled by the ordinary instruction given
there. Dr Hope's lectures on Chemistry, it is true, interested the boy,
who with his brother Erasmus had made a laboratory in the toolhouse, and
was nicknamed "Gas" by his schoolfellows, while undergoing solemn and
public reprimand from Dr Butler at Shrewsbury School for thus wasting his
time. ("L.L." I. page 35.) But most of the other Edinburgh lectures were
"intolerably dull," "as dull as the professors" themselves, "something
fearful to remember." In after life the memory of these lectures was like
a nightmare to him. He speaks in 1840 of Jameson's lectures as something
"I...for my sins experienced!" ("L.L." I. page 340.) Darwin especially
signalises these lectures on Geology and Zoology, which he attended in his
second year, as being worst of all "incredibly dull. The sole effect they
produced on me was the determination never so long as I lived to read a
book on Geology, or in any way to study the science!" ("L.L." I. page 41.)
The misfortune was that Edinburgh at that time had become the cockpit in
which the barren conflict between "Neptunism" and Plutonism" was being
waged with blind fury and theological bitterness. Jameson and his pupils,
on the one hand, and the friends and disciples of Hutton, on the other,
went to the wildest extremes in opposing each other's peculiar tenets.
Darwin tells us that he actually heard Jameson "in a field lecture at
Salisbury Craigs, discoursing on a trap-dyke, with amygdaloidal margins and
the strata indurated on each side, with volcanic rocks all around us, say
that it was a fissure filled with sediment from above, adding with a sneer
that there were men who maintained that it had been injected from beneath
in a molten condition." ("L.L." I. pages 41-42.) "When I think of this
lecture," added Darwin, "I do not wonder that I determined never to attend
to Geology." (This was written in 1876 and Darwin had in the summer of
1839 revisited and carefully studied the locality ("L.L." I. page 290.) It
is probable that most of Jameson's teaching was of the same controversial
and unilluminating character as this field-lecture at Salisbury Craigs.
There can be no doubt that, while at Edinburgh, Darwin must have become
acquainted with the doctrines of the Huttonian School. Though so young, he
mixed freely with the scientific society of the city, Macgillivray, Grant,
Leonard Horner, Coldstream, Ainsworth and others being among his
acquaintances, while he attended and even read papers at the local
scientific societies. It is to be feared, however, that what Darwin would
hear most of, as characteristic of the Huttonian teaching, would be
assertions that chalk-flints were intrusions of molten silica, that fossil
wood and other petrifactions had been impregnated with fused materials,
that heat--but never water--was always the agent by which the induration
and crystallisation of rock-materials (even siliceous conglomerate,
limestone and rock-salt) had been effected! These extravagant "anti-
Wernerian" views the young student might well regard as not one whit less
absurd and repellant than the doctrine of the "aqueous precipitation" of
basalt. There is no evidence that Darwin, even if he ever heard of them,
was in any way impressed, in his early career, by the suggestive passages
in Hutton and Playfair, to which Lyell afterwards called attention, and
which foreshadowed the main principles of Uniformitarianism.
As a matter of fact, I believe that the influence of Hutton and Playfair in
the development of a philosophical theory of geology has been very greatly
exaggerated by later writers on the subject. Just as Wells and Matthew
anticipated the views of Darwin on Natural Selection, but without producing
any real influence on the course of biological thought, so Hutton and
Playfair adumbrated doctrines which only became the basis of vivifying
theory in the hands of Lyell. Alfred Russel Wallace has very justly
remarked that when Lyell wrote the "Principles of Geology", "the doctrines
of Hutton and Playfair, so much in advance of their age, seemed to be
utterly forgotten." ("Quarterly Review", Vol. CXXVI. (1869), page 363.)
In proof of this it is only necessary to point to the works of the great
masters of English geology, who preceded Lyell, in which the works of
Hutton and his followers are scarcely ever mentioned. This is true even of
the "Researches in Theoretical Geology" and the other works of the
sagacious De la Beche. (Of the strength and persistence of the prejudice
felt against Lyell's views by his contemporaries, I had a striking
illustration some little time after Lyell's death. One of the old
geologists who in the early years of the century had done really good work
in connection with the Geological Society expressed a hope that I was not
"one of those who had been carried away by poor Lyell's fads." My surprise
was indeed great when further conversation showed me that the whole of the
"Principles" were included in the "fads"!) Darwin himself possessed a copy
of Playfair's "Illustrations of the Huttonian Theory", and occasionally
quotes it; but I have met with only one reference to Hutton, and that a
somewhat enigmatical one, in all Darwin's writings. In a letter to Lyell
in 1841, when his mind was much exercised concerning glacial questions, he
says "What a grand new feature all this ice work is in Geology! How old
Hutton would have stared!" ("M.L." II. page 149.)
As a consequence of the influences brought to bear on his mind during his
two years' residence in Edinburgh, Darwin, who had entered that University
with strong geological aspirations, left it and proceeded to Cambridge with
a pronounced distaste for the whole subject. The result of this was that,
during his career as an under-graduate, he neglected all the opportunities
for geological study. During that important period of life, when he was
between eighteen and twenty years of age, Darwin spent his time in riding,
shooting and beetle-hunting, pursuits which were undoubtedly an admirable
preparation for his future work as an explorer; but in none of his letters
of this period does he even mention geology. He says, however, "I was so
sickened with lectures at Edinburgh that I did not even attend Sedgwick's
eloquent and interesting lectures." ("L.L." I. page 48.)
It was only after passing his examination, and when he went up to spend two
extra terms at Cambridge, that geology again began to attract his
attention. The reading of Sir John Herschel's "Introduction to the Study
of Natural Philosophy", and of Humboldt's "Personal Narrative", a copy of
which last had been given to him by his good friend and mentor Henslow,
roused his dormant enthusiasm for science, and awakened in his mind a
passionate desire for travel. And it was from Henslow, whom he had
accompanied in his excursions, but without imbibing any marked taste, at
that time, for botany, that the advice came to think of and to "begin the
study of geology." ("L.L." I. page 56.) This was in 1831, and in the
summer vacation of that year we find him back again at Shrewsbury "working
like a tiger" at geology and endeavouring to make a map and section of
Shropshire--work which he says was not "as easy as I expected." ("L.L." I.
page 189.) No better field for geological studies could possibly be found
than Darwin's native county.
Writing to Henslow at this time, and referring to a form of the instrument
devised by his friend, Darwin says: "I am very glad to say I think the
clinometer will answer admirably. I put all the tables in my bedroom at
every conceivable angle and direction. I will venture to say that I have
measured them as accurately as any geologist going could do." But he adds:
"I have been working at so many things that I have not got on much with
geology. I suspect the first expedition I take, clinometer and hammer in
hand, will send me back very little wiser and a good deal more puzzled than
when I started." ("L.L." I. page 189.) Valuable aid was, however, at
hand, for at this time Sedgwick, to whom Darwin had been introduced by the
ever-helpful Henslow, was making one of his expeditions into Wales, and
consented to accept the young student as his companion during the
geological tour. ("L.L." I. page 56.) We find Darwin looking forward to
this privilege with the keenest interest. ("L.L." I. page 189.)
When at the beginning of August (1831), Sedgwick arrived at his father's
house in Shrewsbury, where he spent a night, Darwin began to receive his
first and only instruction as a field-geologist. The journey they took
together led them through Llangollen, Conway, Bangor, and Capel Curig, at
which latter place they parted after spending many hours in examining the
rocks at Cwm Idwal with extreme care, seeking for fossils but without
success. Sedgwick's mode of instruction was admirable--he from time to
time sent the pupil off on a line parallel to his own, "telling me to bring
back specimens of the rocks and to mark the stratification on a map."
("L.L." I. page 57.) On his return to Shrewsbury, Darwin wrote to Henslow,
"My trip with Sedgwick answered most perfectly," ("L.L." I. page 195.), and
in the following year he wrote again from South America to the same friend,
"Tell Professor Sedgwick he does not know how much I am indebted to him for
the Welsh expedition; it has given me an interest in Geology which I would
not give up for any consideration. I do not think I ever spent a more
delightful three weeks than pounding the north-west mountains." ("L.L." I.
pages 237-8.)
It would be a mistake, however, to suppose that at this time Darwin had
acquired anything like the affection for geological study, which he
afterwards developed. After parting with Sedgwick, he walked in a straight
line by compass and map across the mountains to Barmouth to visit a reading
party there, but taking care to return to Shropshire before September 1st,
in order to be ready for the shooting. For as he candidly tells us, "I
should have thought myself mad to give up the first days of partridge-
shooting for geology or any other science!" ("L.L." I. page 58.)
Any regret we may be disposed to feel that Darwin did not use his
opportunities at Edinburgh and Cambridge to obtain systematic and practical
instruction in mineralogy and geology, will be mitigated, however, when we
reflect on the danger which he would run of being indoctrinated with the
crude "catastrophic" views of geology, which were at that time prevalent in
all the centres of learning.
Writing to Henslow in the summer of 1831, Darwin says "As yet I have only
indulged in hypotheses, but they are such powerful ones that I suppose, if
they were put into action but for one day, the world would come to an end."
("L.L." I. page 189.)
May we not read in this passage an indication that the self-taught
geologist had, even at this early stage, begun to feel a distrust for the
prevalent catastrophism, and that his mind was becoming a field in which
the seeds which Lyell was afterwards to sow would "fall on good ground"?
The second period of Darwin's geological career--the five years spent by
him on board the "Beagle"--was the one in which by far the most important
stage in his mental development was accomplished. He left England a
healthy, vigorous and enthusiastic collector; he returned five years later
with unique experiences, the germs of great ideas, and a knowledge which
placed him at once in the foremost ranks of the geologists of that day.
Huxley has well said that "Darwin found on board the "Beagle" that which
neither the pedagogues of Shrewsbury, nor the professoriate of Edinburgh,
nor the tutors of Cambridge had managed to give him." ("Proc. Roy. Soc."
Vol. XLIV. (1888), page IX.) Darwin himself wrote, referring to the date
at which the voyage was expected to begin: "My second life will then
commence, and it shall be as a birthday for the rest of my life." ("L.L."
I. page 214.); and looking back on the voyage after forty years, he wrote;
"The voyage of the 'Beagle' has been by far the most important event in my
life, and has determined my whole career;...I have always felt that I owe
to the voyage the first real training or education of my mind; I was led to
attend closely to several branches of natural history, and thus my powers
of observation were improved, though they were always fairly developed."
("L.L." I. page 61.)
Referring to these general studies in natural history, however, Darwin adds
a very significant remark: "The investigation of the geology of the places
visited was far more important, as reasoning here comes into play. On
first examining a new district nothing can appear more hopeless than the
chaos of rocks; but by recording the stratification and nature of the rocks
and fossils at many points, always reasoning and predicting what will be
found elsewhere, light soon begins to dawn on the district, and the
structure of the whole becomes more or less intelligible." ("L.L." I. page
62.)
The famous voyage began amid doubts, discouragements and disappointments.
Fearful of heart-disease, sad at parting from home and friends, depressed
by sea-sickness, the young explorer, after being twice driven back by
baffling winds, reached the great object of his ambition, the island of
Teneriffe, only to find that, owing to quarantine regulations, landing was
out of the question.
But soon this inauspicious opening of the voyage was forgotten. Henslow
had advised his pupil to take with him the first volume of Lyell's
"Principles of Geology", then just published--but cautioned him (as nearly
all the leaders in geological science at that day would certainly have
done) "on no account to accept the views therein advocated." ("L.L." I.
page 73.) It is probable that the days of waiting, discomfort and sea-
sickness at the beginning of the voyage were relieved by the reading of
this volume. For he says that when he landed, three weeks after setting
sail from Plymouth, in St Jago, the largest of the Cape de Verde Islands,
the volume had already been "studied attentively; and the book was of the
highest service to me in many ways..." His first original geological work,
he declares, "showed me clearly the wonderful superiority of Lyell's manner
of treating geology, compared with that of any other author, whose works I
had with me or ever afterwards read." ("L.L." I. page 62.)
At St Jago Darwin first experienced the joy of making new discoveries, and
his delight was unbounded. Writing to his father he says, "Geologising in
a volcanic country is most delightful; besides the interest attached to
itself, it leads you into most beautiful and retired spots." ("L.L." I.
page 228.) To Henslow he wrote of St Jago: "Here we spent three most
delightful weeks...St Jago is singularly barren, and produces few plants or
insects, so that my hammer was my usual companion, and in its company most
delightful hours I spent." "The geology was pre-eminently interesting, and
I believe quite new; there are some facts on a large scale of upraised
coast (which is an excellent epoch for all the volcanic rocks to date
from), that would interest Mr Lyell." ("L.L." I. page 235.) After more
than forty years the memory of this, his first geological work, seems as
fresh as ever, and he wrote in 1876, "The geology of St Jago is very
striking, yet simple: a stream of lava formerly flowed over the bed of the
sea, formed of triturated recent shells and corals, which it has baked into
a hard white rock. Since then the whole island has been upheaved. But the
line of white rock revealed to me a new and important fact, namely, that
there had been afterwards subsidence round the craters, which had since
been in action, and had poured forth lava." ("L.L." I. page 65.)
It was at this time, probably, that Darwin made his first attempt at
drawing a sketch-map and section to illustrate the observations he had made
(see his "Volcanic Islands", pages 1 and 9). His first important
geological discovery, that of the subsidence of strata around volcanic
vents (which has since been confirmed by Mr Heaphy in New Zealand and other
authors) awakened an intense enthusiasm, and he writes: "It then first
dawned on me that I might perhaps write a book on the geology of the
various countries visited, and this made me thrill with delight. That was
a memorable hour to me, and how distinctly I can call to mind the low cliff
of lava beneath which I rested, with the sun glaring hot, a few strange
desert plants growing near, and with living corals in the tidal pools at my
feet." ("L.L." I. page 66.)
But it was when the "Beagle", after touching at St Paul's rock and Tristan
d'Acunha (for a sufficient time only to collect specimens), reached the
shores of South America, that Darwin's real work began; and he was able,
while the marine surveys were in progress, to make many extensive journeys
on land. His letters at this time show that geology had become his chief
delight, and such exclamations as "Geology carries the day," "I find in
Geology a never failing interest," etc. abound in his correspondence.
Darwin's time was divided between the study of the great deposits of red
mud--the Pampean formation--with its interesting fossil bones and shells
affording proofs of slow and constant movements of the land, and the
underlying masses of metamorphic and plutonic rocks. Writing to Henslow in
March, 1834, he says: "I am quite charmed with Geology, but, like the wise
animal between two bundles of hay, I do not know which to like best; the
old crystalline groups of rocks, or the softer and fossiliferous beds.
When puzzling about stratification, etc., I feel inclined to cry 'a fig for
your big oysters, and your bigger megatheriums.' But then when digging out
some fine bones, I wonder how any man can tire his arms with hammering
granite." ("L.L." I. page 249.) We are told by Darwin that he loved to
reason about and attempt to predict the nature of the rocks in each new
district before he arrived at it.
This love of guessing as to the geology of a district he was about to visit
is amusingly expressed by him in a letter (of May, 1832) to his cousin and
old college-friend, Fox. After alluding to the beetles he had been
collecting--a taste his friend had in common with himself--he writes of
geology that "It is like the pleasure of gambling. Speculating on first
arriving, what the rocks may be, I often mentally cry out 3 to 1 tertiary
against primitive; but the latter have hitherto won all the bets." ("L.L."
I. page 233.)
Not the least important of the educational results of the voyage to Darwin
was the acquirement by him of those habits of industry and method which
enabled him in after life to accomplish so much--in spite of constant
failures of health. From the outset, he daily undertook and resolutely
accomplished, in spite of sea-sickness and other distractions, four
important tasks. In the first place he regularly wrote up the pages of his
Journal, in which, paying great attention to literary style and
composition, he recorded only matters that would be of general interest,
such as remarks on scenery and vegetation, on the peculiarities and habits
of animals, and on the characters, avocations and political institutions of
the various races of men with whom he was brought in contact. It was the
freshness of these observations that gave his "Narrative" so much charm.
Only in those cases in which his ideas had become fully crystallised, did
he attempt to deal with scientific matters in this journal. His second
task was to write in voluminous note-books facts concerning animals and
plants, collected on sea or land, which could not be well made out from
specimens preserved in spirit; but he tells us that, owing to want of skill
in dissecting and drawing, much of the time spent in this work was entirely
thrown away, "a great pile of MS. which I made during the voyage has proved
almost useless." ("L.L." I. page 62.) Huxley confirmed this judgment on
his biological work, declaring that "all his zeal and industry resulted,
for the most part, in a vast accumulation of useless manuscript." ("Proc.
Roy. Soc." Vol. XLIV. (1888), page IX.) Darwin's third task was of a very
different character and of infinitely greater value. It consisted in
writing notes of his journeys on land--the notes being devoted to the
geology of the districts visited by him. These formed the basis, not only
of a number of geological papers published on his return, but also of the
three important volumes forming "The Geology of the voyage of the
'Beagle'". On July 24th, 1834, when little more than half of the voyage
had been completed, Darwin wrote to Henslow, "My notes are becoming bulky.
I have about 600 small quarto pages full; about half of this is Geology."
("M.L." I. page 14.) The last, and certainly not the least important of
all his duties, consisted in numbering, cataloguing, and packing his
specimens for despatch to Henslow, who had undertaken the care of them. In
his letters he often expresses the greatest solicitude lest the value of
these specimens should be impaired by the removal of the numbers
corresponding to his manuscript lists. Science owes much to Henslow's
patient care of the collections sent to him by Darwin. The latter wrote in
Henslow's biography, "During the five years' voyage, he regularly
corresponded with me and guided my efforts; he received, opened, and took
care of all the specimens sent home in many large boxes." ("Life of
Henslow", by L. Jenyns (Blomefield), London, 1862, page 53.)
Darwin's geological specimens are now very appropriately lodged for the
most part in the Sedgwick Museum, Cambridge, his original Catalogue with
subsequent annotations being preserved with them. From an examination of
these catalogues and specimens we are able to form a fair notion of the
work done by Darwin in his little cabin in the "Beagle", in the intervals
between his land journeys.
Besides writing up his notes, it is evident that he was able to accomplish
a considerable amount of study of his specimens, before they were packed up
for despatch to Henslow. Besides hand-magnifiers and a microscope, Darwin
had an equipment for blowpipe-analysis, a contact-goniometer and magnet;
and these were in constant use by him. His small library of reference (now
included in the Collection of books placed by Mr F. Darwin in the Botany
School at Cambridge ("Catalogue of the Library of Charles Darwin now in the
Botany School, Cambridge". Compiled by H.W. Rutherford; with an
introduction by Francis Darwin. Cambridge, 1908.)) appears to have been
admirably selected, and in all probability contained (in addition to a good
many works relating to South America) a fair number of excellent books of
reference. Among those relating to mineralogy, he possessed the manuals of
Phillips, Alexander Brongniart, Beudant, von Kobell and Jameson: all the
"Cristallographie" of Brochant de Villers and, for blowpipe work, Dr
Children's translation of the book of Berzelius on the subject. In
addition to these, he had Henry's "Experimental Chemistry" and Ure's
"Dictionary" (of Chemistry). A work, he evidently often employed, was P.
Syme's book on "Werner's Nomenclature of Colours"; while, for Petrology, he
used Macculloch's "Geological Classification of Rocks". How diligently and
well he employed his instruments and books is shown by the valuable
observations recorded in the annotated Catalogues drawn up on board ship.
These catalogues have on the right-hand pages numbers and descriptions of
the specimens, and on the opposite pages notes on the specimens--the result
of experiments made at the time and written in a very small hand. Of the
subsequently made pencil notes, I shall have to speak later. (I am greatly
indebted to my friend Mr A. Harker, F.R.S., for his assistance in examining
these specimens and catalogues. He has also arranged the specimens in the
Sedgwick Museum, so as to make reference to them easy. The specimens from
Ascension and a few others are however in the Museum at Jermyn Street.)
It is a question of great interest to determine the period and the occasion
of Darwin's first awakening to the great problem of the transmutation of
species. He tells us himself that his grandfather's "Zoonomia" had been
read by him "but without producing any effect," and that his friend Grant's
rhapsodies on Lamarck and his views on evolution only gave rise to
"astonishment." ("L.L." I. page 38.)
Huxley, who had probably never seen the privately printed volume of letters
to Henslow, expressed the opinion that Darwin could not have perceived the
important bearing of his discovery of bones in the Pampean Formation, until
they had been studied in England, and their analogies pronounced upon by
competent comparative anatomists. And this seemed to be confirmed by
Darwin's own entry in his pocket-book for 1837, "In July opened first
notebook on Transmutation of Species. Had been greatly struck from about
the month of previous March on character of South American fossils..."
("L.L." I. page 276.)
The second volume of Lyell's "Principles of Geology" was published in
January, 1832, and Darwin's copy (like that of the other two volumes, in a
sadly dilapidated condition from constant use) has in it the inscription,
"Charles Darwin, Monte Video. Nov. 1832." As everyone knows, Darwin in
dedicating the second edition of his Journal of the Voyage to Lyell
declared, "the chief part of whatever scientific merit this journal and the
other works of the author may possess, has been derived from studying the
well-known and admirable "Principles of Geology".
In the first chapter of this second volume of the "Principles", Lyell
insists on the importance of the species question to the geologist, but
goes on to point out the difficulty of accepting the only serious attempt
at a transmutation theory which had up to that time appeared--that of
Lamarck. In subsequent chapters he discusses the questions of the
modification and variability of species, of hybridity, and of the
geographical distribution of plants and animals. He then gives vivid
pictures of the struggle for existence, ever going on between various
species, and of the causes which lead to their extinction--not by
overwhelming catastrophes, but by the silent and almost unobserved action
of natural causes. This leads him to consider theories with regard to the
introduction of new species, and, rejecting the fanciful notions of
"centres or foci of creation," he argues strongly in favour of the view, as
most reconcileable with observed facts, that "each species may have had its
origin in a single pair, or individual, where an individual was sufficient,
and species may have been created in succession at such times and in such
places as to enable them to multiply and endure for an appointed period,
and occupy an appointed space on the globe." ("Principles of Geology",
Vol. II. (1st edition 1832), page 124. We now know, as has been so well
pointed out by Huxley, that Lyell, as early as 1827, was prepared to accept
the doctrine of the transmutation of species. In that year he wrote to
Mantell, "What changes species may really undergo! How impossible will it
be to distinguish and lay down a line, beyond which some of the so-called
extinct species may have never passed into recent ones" (Lyell's "Life and
Letters" Vol. I. page 168). To Sir John Herschel in 1836, he wrote, "In
regard to the origination of new species, I am very glad to find that you
think it probable that it may be carried on through the intervention of
intermediate causes. I left this rather to be inferred, not thinking it
worth while to offend a certain class of persons by embodying in words what
would only be a speculation" (Ibid. page 467). He expressed the same views
to Whewell in 1837 (Ibid. Vol. II. page 5.), and to Sedgwick (Ibid. Vol.
II. page 36) to whom he says, of "the theory, that the creation of new
species is going on at the present day"--"I really entertain it," but "I
have studiously avoided laying the doctrine down dogmatically as capable of
proof" (see Huxley in "L.L." II. pages 190-195.))
After pointing out how impossible it would be for a naturalist to prove
that a newly DISCOVERED species was really newly CREATED (Mr F. Darwin has
pointed out that his father (like Lyell) often used the term "Creation" in
speaking of the origin of new species ("L.L." II. chapter 1.)), Lyell
argued that no satisfactory evidence OF THE WAY in which these new forms
were created, had as yet been discovered, but that he entertained the hope
of a possible solution of the problem being found in the study of the
geological record.
It is not difficult, in reading these chapters of Lyell's great work, to
realise what an effect they would have on the mind of Darwin, as new facts
were collected and fresh observations concerning extinct and recent forms
were made in his travels. We are not surprised to find him writing home,
"I am become a zealous disciple of Mr Lyell's views, as known in his
admirable book. Geologising in South America, I am tempted to carry parts
to a greater extent even than he does." ("L.L." I. page 263.)
Lyell's anticipation that the study of the geological record might afford a
clue to the discovery of how new species originate was remarkably
fulfilled, within a few months, by Darwin's discovery of fossil bones in
the red Pampean mud.
It is very true that, as Huxley remarked, Darwin's knowledge of comparative
anatomy must have been, at that time, slight; but that he recognised the
remarkable resemblances between the extinct and existing mammals of South
America is proved beyond all question by a passage in his letter to
Henslow, written November 24th, 1832: "I have been very lucky with fossil
bones; I have fragments of at least six distinct animals...I found a large
surface of osseous polygonal plates...Immediately I saw them I thought they
must belong to an enormous armadillo, living species of which genus are so
abundant here," and he goes on to say that he has "the lower jaw of some
large animal which, from the molar teeth, I should think belonged to the
Edentata." ("M.L." I. pages 11, 12. See "Extracts of Letters addressed to
Prof. Henslow by C. Darwin" (1835), page 7.)
Having found this important clue, Darwin followed it up with characteristic
perseverance. In his quest for more fossil bones he was indefatigable. Mr
Francis Darwin tells us, "I have often heard him speak of the despair with
which he had to break off the projecting extremity of a huge, partly
excavated bone, when the boat waiting for him would wait no longer."
("L.L." I. page 276 (footnote).) Writing to Haeckel in 1864, Darwin says:
"I shall never forget my astonishment when I dug out a gigantic piece of
armour, like that of the living armadillo." (Haeckel, "History of
Creation", Vol. I. page 134, London, 1876.)
In a letter to Henslow in 1834 Darwin says: "I have just got scent of some
fossil bones...what they may be I do not know, but if gold or galloping
will get them they shall be mine." ("M.L." I. page 15.)
Darwin also showed his sense of the importance of the discovery of these
bones by his solicitude about their safe arrival and custody. From the
Falkland Isles (March, 1834), he writes to Henslow: "I have been alarmed
by your expression 'cleaning all the bones' as I am afraid the printed
numbers will be lost: the reason I am so anxious they should not be, is,
that a part were found in a gravel with recent shells, but others in a very
different bed. Now with these latter there were bones of an Agouti, a
genus of animals, I believe, peculiar to America, and it would be curious
to prove that some one of the genus co-existed with the Megatherium: such
and many other points depend on the numbers being carefully preserved."
("Extracts from Letters etc.", pages 13-14.) In the abstract of the notes
read to the Geological Society in 1835, we read: "In the gravel of
Patagonia he (Darwin) also found many bones of the Megatherium and of five
or six other species of quadrupeds, among which he has detected the bones
of a species of Agouti. He also met with several examples of the polygonal
plates, etc." ("Proc. Geol. Soc." Vol. II. pages 211-212.)
Darwin's own recollections entirely bear out the conclusion that he fully
recognised, WHILE IN SOUTH AMERICA, the wonderful significance of the
resemblances between the extinct and recent mammalian faunas. He wrote in
his "Autobiography": "During the voyage of the 'Beagle' I had been deeply
impressed by discovering in the Pampean formation great fossil animals
covered with armour like that on the existing armadillos." ("L.L." I. page
82.)
The impression made on Darwin's mind by the discovery of these fossil
bones, was doubtless deepened as, in his progress southward from Brazil to
Patagonia, he found similar species of Edentate animals everywhere
replacing one another among the living forms, while, whenever fossils
occurred, they also were seen to belong to the same remarkable group of
animals. (While Darwin was making these observations in South America, a
similar generalisation to that at which he arrived was being reached, quite
independently and almost simultaneously, with respect to the fossil and
recent mammals of Australia. In the year 1831, Clift gave to Jameson a
list of bones occurring in the caves and breccias of Australia, and in
publishing this list the latter referred to the fact that the forms
belonged to marsupials, similar to those of the existing Australian fauna.
But he also stated that, as a skull had been identified (doubtless
erroneously) as having belonged to a hippopotamus, other mammals than
marsupials must have spread over the island in late Tertiary times. It is
not necessary to point out that this paper was quite unknown to Darwin
while in South America. Lyell first noticed it in the third edition of his
"Principles", which was published in May, 1834 (see "Edinb. New Phil.
Journ." Vol. X. (1831), pages 394-6, and Lyell's "Principles" (3rd
edition), Vol. III. page 421). Darwin referred to this discovery in 1839
(see his "Journal", page 210.)
That the passage in Darwin's pocket-book for 1837 can only refer to an
AWAKENING of Darwin's interest in the subject--probably resulting from a
sight of the bones when they were being unpacked--I think there cannot be
the smallest doubt; AND WE MAY THEREFORE CONFIDENTLY FIX UPON NOVEMBER,
1832, AS THE DATE AT WHICH DARWIN COMMENCED THAT LONG SERIES OF
OBSERVATIONS AND REASONINGS WHICH EVENTUALLY CULMINATED IN THE PREPARATION
OF THE "ORIGIN OF SPECIES". Equally certain is it, that it was his
geological work that led Darwin into those paths of research which in the
end conducted him to his great discoveries. I quite agree with the view
expressed by Mr F. Darwin and Professor Seward, that Darwin, like Lyell,
"thought it 'almost useless' to try to prove the truth of evolution until
the cause of change was discovered" ("M.L." I. page 38.), and that possibly
he may at times have vacillated in his opinions, but I believe there is
evidence that, from the date mentioned, the "species question" was always
more or less present in Darwin's mind. (Although we admit with Huxley that
Darwin's training in comparative anatomy was very small, yet it may be
remembered that he was a medical student for two years, and, if he hated
the lectures, he enjoyed the society of naturalists. He had with him in
the little "Beagle" library a fair number of zoological books, including
works on Osteology by Cuvier, Desmarest and Lesson, as well as two French
Encyclopaedias of Natural History. As a sportsman, he would obtain
specimens of recent mammals in South America, and would thus have
opportunities of studying their teeth and general anatomy. Keen observer,
as he undoubtedly was, we need not then be surprised that he was able to
make out the resemblances between the recent and fossil forms.)
It is clear that, as time went on, Darwin became more and more absorbed in
his geological work. One very significant fact was that the once ardent
sportsman, when he found that shooting the necessary game and zoological
specimens interfered with his work with the hammer, gave up his gun to his
servant. ("L.L." I. page 63.) There is clear evidence that Darwin
gradually became aware how futile were his attempts to add to zoological
knowledge by dissection and drawing, while he felt ever increasing
satisfaction with his geological work.
The voyage fortunately extended to a much longer period (five years) than
the two originally intended, but after being absent nearly three years,
Darwin wrote to his sister in November, 1834, "Hurrah! hurrah! it is fixed
that the 'Beagle' shall not go one mile south of Cape Tres Montes (about
200 miles south of Chiloe), and from that point to Valparaiso will be
finished in about five months. We shall examine the Chonos Archipelago,
entirely unknown, and the curious inland sea behind Chiloe. For me it is
glorious. Cape Tres Montes is the most southern point where there is much
geological interest, as there the modern beds end. The Captain then talks
of crossing the Pacific; but I think we shall persuade him to finish the
coast of Peru, where the climate is delightful, the country hideously
sterile, but abounding with the highest interest to the geologist...I have
long been grieved and most sorry at the interminable length of the voyage
(though I never would have quitted it)...I could not make up my mind to
return. I could not give up all the geological castles in the air I had
been building up for the last two years." ("L.L." I. pages 257-58.)
In April, 1835, he wrote to another sister: "I returned a week ago from my
excursion across the Andes to Mendoza. Since leaving England I have never
made so successful a journey...how deeply I have enjoyed it; it was
something more than enjoyment; I cannot express the delight which I felt at
such a famous winding-up of all my geology in South America. I literally
could hardly sleep at nights for thinking over my day's work. The scenery
was so new, and so majestic; everything at an elevation of 12,000 feet
bears so different an aspect from that in the lower country...To a
geologist, also, there are such manifest proofs of excessive violence; the
strata of the highest pinnacles are tossed about like the crust of a broken
pie." ("L.L." I. pages 259-60.)
Darwin anticipated with intense pleasure his visit to the Galapagos
Islands. On July 12th, 1835, he wrote to Henslow: "In a few days' time
the "Beagle" will sail for the Galapagos Islands. I look forward with joy
and interest to this, both as being somewhat nearer to England and for the
sake of having a good look at an active volcano. Although we have seen
lava in abundance, I have never yet beheld the crater." ("M.L." I. page
26.) He could little anticipate, as he wrote these lines, the important
aid in the solution of the "species question" that would ever after make
his visit to the Galapagos Islands so memorable. In 1832, as we have seen,
the great discovery of the relations of living to extinct mammals in the
same area had dawned upon his mind; in 1835 he was to find a second key for
opening up the great mystery, by recognising the variations of similar
types in adjoining islands among the Galapagos.
The final chapter in the second volume of the "Principles" had aroused in
Darwin's mind a desire to study coral-reefs, which was gratified during his
voyage across the Pacific and Indian Oceans. His theory on the subject was
suggested about the end of 1834 or the beginning of 1835, as he himself
tells us, before he had seen a coral-reef, and resulted from his work
during two years in which he had "been incessantly attending to the effects
on the shores of South America of the intermittent elevation of the land,
together with denudation and the deposition of sediment." ("L.L." I. page
70.)
On arriving at the Cape of Good Hope in July, 1836, Darwin was greatly
gratified by hearing that Sedgwick had spoken to his father in high terms
of praise concerning the work done by him in South America. Referring to
the news from home, when he reached Bahia once more, on the return voyage
(August, 1836), he says: "The desert, volcanic rocks, and wild sea of
Ascension...suddenly wore a pleasing aspect, and I set to work with a good-
will at my old work of Geology." ("L.L." I. page 265.) Writing fifty
years later, he says: "I clambered over the mountains of Ascension with a
bounding step and made the volcanic rocks resound under my geological
hammer!" ("L.L." I. page 66.)
That his determination was now fixed to devote his own labours to the task
of working out the geological results of the voyage, and that he was
prepared to leave to more practised hands the study of his biological
collections, is clear from the letters he sent home at this time. From St
Helena he wrote to Henslow asking that he would propose him as a Fellow of
the Geological Society; and his Certificate, in Henslow's handwriting, is
dated September 8th, 1836, being signed from personal knowledge by Henslow
and Sedgwick. He was proposed on November 2nd and elected November 30th,
being formally admitted to the Society by Lyell, who was then President, on
January 4th, 1837, on which date he also read his first paper. Darwin did
not become a Fellow of the Linnean Society till eighteen years later (in
1854).
An estimate of the value and importance of Darwin's geological discoveries
during the voyage of the "Beagle" can best be made when considering the
various memoirs and books in which the author described them. He was too
cautious to allow himself to write his first impressions in his Journal,
and wisely waited till he could study his specimens under better conditions
and with help from others on his return. The extracts published from his
correspondence with Henslow and others, while he was still abroad, showed,
nevertheless, how great was the mass of observation, how suggestive and
pregnant with results were the reasonings of the young geologist.
Two sets of these extracts from Darwin's letters to Henslow were printed
while he was still abroad. The first of these was the series of
"Geological Notes made during a survey of the East and West Coasts of South
America, in the years 1832, 1833, 1834 and 1835, with an account of a
transverse section of the Cordilleras of the Andes between Valparaiso and
Mendoza". Professor Sedgwick, who read these notes to the Geological
Society on November 18th, 1835, stated that "they were extracted from a
series of letters (addressed to Professor Henslow), containing a great mass
of information connected with almost every branch of natural history," and
that he (Sedgwick) had made a selection of the remarks which he thought
would be more especially interesting to the Geological Society. An
abstract of three pages was published in the "Proceedings of the Geological
Society" (Vol. II. pages 210-12.), but so unknown was the author at this
time that he was described as F. Darwin, Esq., of St John's College,
Cambridge"! Almost simultaneously (on November 16th, 1835) a second set of
extracts from these letters--this time of a general character--were read to
the Philosophical Society at Cambridge, and these excited so much interest
that they were privately printed in pamphlet form for circulation among the
members.
Many expeditions and "scientific missions" have been despatched to various
parts of the world since the return of the "Beagle" in 1836, but it is
doubtful whether any, even the most richly endowed of them, has brought
back such stores of new information and fresh discoveries as did that
little "ten-gun brig"--certainly no cabin or laboratory was the birth-place
of ideas of such fruitful character as was that narrow end of a chart-room,
where the solitary naturalist could climb into his hammock and indulge in
meditation.
The third and most active portion of Darwin's career as a geologist was the
period which followed his return to England at the end of 1836. His
immediate admission to the Geological Society, at the beginning of 1837,
coincided with an important crisis in the history of geological science.
The band of enthusiasts who nearly thirty years before had inaugurated the
Geological Society--weary of the fruitless conflicts between "Neptunists"
and "Plutonists"--had determined to eschew theory and confine their labours
to the collection of facts, their publications to the careful record of
observations. Greenough, the actual founder of the Society, was an ardent
Wernerian, and nearly all his fellow-workers had come, more or less
directly, under the Wernerian teaching. Macculloch alone gave valuable
support to the Huttonian doctrines, so far as they related to the influence
of igneous activity--but the most important portion of the now celebrated
"Theory of the Earth"--that dealing with the competency of existing
agencies to account for changes in past geological times--was ignored by
all alike. Macculloch's influence on the development of geology, which
might have had far-reaching effects, was to a great extent neutralised by
his peculiarities of mind and temper; and, after a stormy and troublous
career, he retired from the society in 1832. In all the writings of the
great pioneers in English geology, Hutton and his splendid generalisation
are scarcely ever referred to. The great doctrines of Uniformitarianism,
which he had foreshadowed, were completely ignored, and only his
extravagances of "anti-Wernerianism" seem to have been remembered.
When between 1830 and 1832, Lyell, taking up the almost forgotten ideas of
Hutton, von Hoff and Prevost, published that bold challenge to the
Catastrophists--the "Principles of Geology"--he was met with the strongest
opposition, not only from the outside world, which was amused by his
"absurdities" and shocked by his "impiety"--but not less from his fellow-
workers and friends in the Geological Society. For Lyell's numerous
original observations, and his diligent collection of facts his
contemporaries had nothing but admiration, and they cheerfully admitted him
to the highest offices in the society, but they met his reasonings on
geological theory with vehement opposition and his conclusions with
coldness and contempt.
There is, indeed, a very striking parallelism between the reception of the
"Principles of Geology" by Lyell's contemporaries and the manner in which
the "Origin of Species" was met a quarter of a century later, as is so
vividly described by Huxley. ("L.L." II. pages 179-204.) Among Lyell's
fellow-geologists, two only--G. Poulett Scrope and John Herschel (Both
Lyell and Darwin fully realised the value of the support of these two
friends. Scrope in his appreciative reviews of the "Principles" justly
pointed out what was the weakest point, the inadequate recognition of sub-
aerial as compared with marine denudation. Darwin also admitted that
Scrope had to a great extent forestalled him in his theory of Foliation.
Herschel from the first insisted that the leading idea of the "Principles"
must be applied to organic as well as to inorganic nature and must explain
the appearance of new species (see Lyell's "Life and Letters", Vol. I. page
467). Darwin tells us that Herschel's "Introduction to the Study of
Natural Philosophy" with Humboldt's "Personal Narrative" "stirred up in me
a burning zeal" in his undergraduate days. I once heard Lyell exclaim with
fervour "If ever there was a heaven-born genius it was John Herschel!")--
declared themselves from the first his strong supporters. Scrope in two
luminous articles in the "Quarterly Review" did for Lyell what Huxley
accomplished for Darwin in his famous review in the "Times"; but Scrope
unfortunately was at that time immersed in the stormy sea of politics, and
devoted his great powers of exposition to the preparation of fugitive
pamphlets. Herschel, like Scrope, was unable to support Lyell at the
Geological Society, owing to his absence on the important astronomical
mission to the Cape.
It thus came about that, in the frequent conflicts of opinion within the
walls of the Geological Society, Lyell had to bear the brunt of battle for
Uniformitarianism quite alone, and it is to be feared that he found himself
sadly overmatched when opposed by the eloquence of Sedgwick, the sarcasm of
Buckland, and the dead weight of incredulity on the part of Greenough,
Conybeare, Murchison and other members of the band of pioneer workers. As
time went on there is evidence that the opposition of De la Beche and
Whewell somewhat relaxed; the brilliant "Paddy" Fitton (as his friends
called him) was sometimes found in alliance with Lyell, but was
characteristically apt to turn his weapon, as occasion served, on friend or
foe alike; the amiable John Phillips "sat upon the fence." Only when a new
generation arose--including Jukes, Ramsay, Forbes and Hooker--did Lyell
find his teachings received with anything like favour.
We can well understand, then, how Lyell would welcome such a recruit as
young Darwin--a man who had declared himself more Lyellian than Lyell, and
who brought to his support facts and observations gleaned from so wide a
field.
The first meeting of Lyell and Darwin was characteristic of the two men.
Darwin at once explained to Lyell that, with respect to the origin of
coral-reefs, he had arrived at views directly opposed to those published by
"his master." To give up his own theory, cost Lyell, as he told Herschel,
a "pang at first," but he was at once convinced of the immeasurable
superiority of Darwin's theory. I have heard members of Lyell's family
tell of the state of wild excitement and sustained enthusiasm, which lasted
for days with Lyell after this interview, and his letters to Herschel,
Whewell and others show his pleasure at the new light thrown upon the
subject and his impatience to have the matter laid before the Geological
Society.
Writing forty years afterwards, Darwin, speaking of the time of the return
of the "Beagle", says: "I saw a great deal of Lyell. One of his chief
characteristics was his sympathy with the work of others, and I was as much
astonished as delighted at the interest which he showed when, on my return
to England, I explained to him my views on coral-reefs. This encouraged me
greatly, and his advice and example had much influence on me." ("L.L." I.
page 68.) Darwin further states that he saw more of Lyell at this time
than of any other scientific man, and at his request sent his first
communication to the Geological Society. ("L.L." I. page 67.)
"Mr Lonsdale" (the able curator of the Geological Society), Darwin wrote to
Henslow, "with whom I had much interesting conversation," "gave me a most
cordial reception," and he adds, "If I was not much more inclined for
geology than the other branches of Natural History, I am sure Mr Lyell's
and Lonsdale's kindness ought to fix me. You cannot conceive anything more
thoroughly good-natured than the heart-and-soul manner in which he put
himself in my place and thought what would be best to do." ("L.L." I. page
275.)
Within a few days of Darwin's arrival in London we find Lyell writing to
Owen as follows:
"Mrs Lyell and I expect a few friends here on Saturday next, 29th
(October), to an early tea party at eight o'clock, and it will give us
great pleasure if you can join it. Among others you will meet Mr Charles
Darwin, whom I believe you have seen, just returned from South America,
where he has laboured for zoologists as well as for hammer-bearers. I have
also asked your friend Broderip." ("The Life of Richard Owen", London,
1894, Vol. I. page 102.) It would probably be on this occasion that the
services of Owen were secured for the work on the fossil bones sent home by
Darwin.
On November 2nd, we find Lyell introducing Darwin as his guest at the
Geological Society Club; on December 14th, Lyell and Stokes proposed Darwin
as a member of the Club; between that date and May 3rd of the following
year, when his election to the Club took place, he was several times dining
as a guest.
On January 4th, 1837, as we have already seen, Darwin was formally admitted
to the Geological Society, and on the same evening he read his first paper
(I have already pointed out that the notes read at the Geological Society
on Nov. 18, 1835 were extracts made by Sedgwick from letters sent to
Henslow, and not a paper sent home for publication by Darwin.) before the
Society, "Observations of proofs of recent elevation on the coast of Chili,
made during the Survey of H.M.S. "Beagle", commanded by Captain FitzRoy,
R.N." By C. Darwin, F.G.S. This paper was preceded by one on the same
subject by Mr A. Caldcleugh, and the reading of a letter and other
communications from the Foreign Office also relating to the earthquakes in
Chili.
At the meeting of the Council of the Geological Society on February 1st,
Darwin was nominated as a member of the new Council, and he was elected on
February 17th.
The meeting of the Geological Society on April 19th was devoted to the
reading by Owen of his paper on Toxodon, perhaps the most remarkable of the
fossil mammals found by Darwin in South America; and at the next meeting,
on May 3rd, Darwin himself read "A Sketch of the Deposits containing
extinct Mammalia in the neighbourhood of the Plata". The next following
meeting, on May 17th, was devoted to Darwin's Coral-reef paper, entitled
"On certain areas of elevation and subsidence in the Pacific and Indian
Oceans, as deduced from the study of Coral Formations". Neither of these
three early papers of Darwin were published in the Transactions of the
Geological Society, but the minutes of the Council show that they were
"withdrawn by the author by permission of the Council."
Darwin's activity during this session led to some rather alarming effects
upon his health, and he was induced to take a holiday in Staffordshire and
the Isle of Wight. He was not idle, however, for a remark of his uncle, Mr
Wedgwood, led him to make those interesting observations on the work done
by earthworms, that resulted in his preparing a short memoir on the
subject, and this paper, "On the Formation of Mould", was read at the
Society on November 1st, 1837, being the first of Darwin's papers published
in full; it appeared in Vol. V. of the "Geological Transactions", pages
505-510.)
During this session, Darwin attended nearly all the Council meetings, and
took such an active part in the work of the Society that it is not
surprising to find that he was now requested to accept the position of
Secretary. After some hesitation, in which he urged his inexperience and
want of knowledge of foreign languages, he consented to accept the
appointment. ("L.L." I. page 285.)
At the anniversary meeting on February 16th, 1838, the Wollaston Medal was
given to Owen in recognition of his services in describing the fossil
mammals sent home by Darwin. In his address, the President, Professor
Whewell, dwelt at length on the great value of the papers which Darwin had
laid before the Society during the preceding session.
On March 7th, Darwin read before the Society the most important perhaps of
all his geological papers, "On the Connexion of certain Volcanic Phenomena
in South America, and on the Formation of Mountain-Chains and Volcanoes as
the effect of Continental Elevations". In this paper he boldly attacked
the tenets of the Catastrophists. It is evident that Darwin at this time,
taking advantage of the temporary improvement in his health, was throwing
himself into the breach of Uniformitarianism with the greatest ardour.
Lyell wrote to Sedgwick on April 21st, 1837, "Darwin is a glorious addition
to any society of geologists, and is working hard and making way, both in
his book and in our discussions." ("The Life and Letters of the Reverend
Adam Sedgwick", Vol. I. page 484, Cambridge, 1890.)
We have unfortunately few records of the animated debates which took place
at this time between the old and new schools of geologists. I have often
heard Lyell tell how Lockhart would bring down a party of friends from the
Athenaeum Club to Somerset House on Geological nights, not, as he carefully
explained, that "he cared for geology, but because he liked to while the
fellows fight." But it fortunately happens that a few days after this last
of Darwin's great field-days, at the Geological Society, Lyell, in a
friendly letter to his father-in-law, Leonard Horner, wrote a very lively
account of the proceedings while his impressions were still fresh; and this
gives us an excellent idea of the character of these discussions.
Neither Sedgwick nor Buckland were present on this occasion, but we can
imagine how they would have chastised their two "erring pupils"--more in
sorrow than in anger--had they been there. Greenough, too, was absent--
possibly unwilling to countenance even by his presence such outrageous
doctrines.
Darwin, after describing the great earthquakes which he had experienced in
South America, and the evidence of their connection with volcanic
outbursts, proceeded to show that earthquakes originated in fractures,
gradually formed in the earth's crust, and were accompanied by movements of
the land on either side of the fracture. In conclusion he boldly advanced
the view "that continental elevations, and the action of volcanoes, are
phenomena now in progress, caused by some great but slow change in the
interior of the earth; and, therefore, that it might be anticipated, that
the formation of mountain chains is likewise in progress: and at a rate
which may be judged of by either actions, but most clearly by the growth of
volcanoes." ("Proc. Geol. Soc." Vol. II. pages 654-60.)
Lyell's account ("Life, Letters and Journals of Sir Charles Lyell, Bart.",
edited by his sister-in-law, Mrs Lyell, Vol. II. pages 40, 41 (Letter to
Leonard Horner, 1838), 2 vols. London, 1881.) of the discussion was as
follows: "In support of my heretical notions," Darwin "opened upon De la
Beche, Phillips and others his whole battery of the earthquakes and
volcanoes of the Andes, and argued that spaces at least a thousand miles
long were simultaneously subject to earthquakes and volcanic eruptions, and
that the elevation of the Pampas, Patagonia, etc., all depended on a common
cause; also that the greater the contortions of strata in a mountain chain,
the smaller must have been each separate and individual movement of that
long series which was necessary to upheave the chain. Had they been more
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