Darwin and Modern Science
A.C. Seward

Part 9 out of 14

violent, he contended that the subterraneous fluid matter would have gushed
out and overflowed, and the strata would have been blown up and
annihilated. (It is interesting to compare this with what Darwin wrote to
Henslow seven years earlier.) He therefore introduces a cooling of one
small underground injection, and then the pumping in of other lava, or
porphyry, or granite, into the previously consolidated and first-formed
mass of igneous rock. (Ideas somewhat similar to this suggestion have
recently been revived by Dr See ("Proc. Am. Phil. Soc." Vol. XLVII. 1908,
page 262.).) When he had done his description of the reiterated strokes of
his volcanic pump, De la Beche gave us a long oration about the
impossibility of strata of the Alps, etc., remaining flexible for such a
time as they must have done, if they were to be tilted, convoluted, or
overturned by gradual small shoves. He never, however, explained his
theory of original flexibility, and therefore I am as unable as ever to
comprehend why flexiblility is a quality so limited in time.

"Phillips then got up and pronounced a panegyric upon the "Principles of
Geology", and although he still differed, thought the actual cause doctrine
had been so well put, that it had advanced the science and formed a date or
era, and that for centuries the two opposite doctrines would divide
geologists, some contending for greater pristine forces, others satisfied,
like Lyell and Darwin, with the same intensity as nature now employs.

"Fitton quizzed Phillips a little for the warmth of his eulogy, saying that
he (Fitton) and others, who had Mr Lyell always with them, were in the
habit of admiring and quarrelling with him every day, as one might do with
a sister or cousin, whom one would only kiss and embrace fervently after a
long absence. This seemed to be Mr Phillips' case, coming up occasionally
from the provinces. Fitton then finished this drollery by charging me with
not having done justice to Hutton, who he said was for gradual elevation.

"I replied, that most of the critics had attacked me for overrating Hutton,
and that Playfair understood him as I did.

"Whewell concluded by considering Hopkins' mathematical calculations, to
which Darwin had often referred. He also said that we ought not to try and
make out what Hutton would have taught and thought, if he had known the
facts which we now know."

It may be necessary to point out, in explanation of the above narrative,
that while it was perfectly clear from Hutton's rather obscure and involved
writings that he advocated slow and gradual change on the earth's surface,
his frequent references to violent action and earthquakes led many--
including Playfair, Lyell and Whewell--to believe that he held the changes
going on in the earth's interior to be of a catastrophic nature. Fitton,
however, maintained that Hutton was consistently uniformitarian. Before
the idea of the actual "flowing" of solid bodies under intense pressure had
been grasped by geologists, De la Beche, like Playfair before him,
maintained that the bending and folding of rocks must have been effected
before their complete consolidation.

In concluding his account of this memorable discussion, Lyell adds: "I was
much struck with the different tone in which my gradual causes was treated
by all, even including De la Beche, from that which they experienced in the
same room four years ago, when Buckland, De la Beche(?), Sedgwick, Whewell,
and some others treated them with as much ridicule as was consistent with
politeness in my presence."

This important paper was, in spite of its theoretical character, published
in full in the "Transactions of the Geological Society" (Ser. 2, Vol. V.
pages 601-630). It did not however appear till 1840, and possibly some
changes may have been made in it during the long interval between reading
and printing. During the year 1839, Darwin continued his regular
attendance at the Council meetings, but there is no record of any
discussions in which he may have taken part, and he contributed no papers
himself to the Society. At the beginning of 1840, he was re-elected for
the third time as Secretary, but the results of failing health are
indicated by the circumstance that, only at one meeting early in the
session, was he able to attend the Council. At the beginning of the next
session (Feb. 1841) Bunbury succeeded him as Secretary, Darwin still
remaining on the Council. It may be regarded as a striking indication of
the esteem in which he was held by his fellow geologists, that Darwin
remained on the Council for 14 consecutive years down to 1849, though his
attendances were in some years very few. In 1843 and 1844 he was a Vice-
president, but after his retirement at the beginning of 1850, he never
again accepted re-nomination. He continued, however, to contribute papers
to the Society, as we shall see, down to the end of 1862.

Although Darwin early became a member of the Geological Dining Club, it is
to be feared that he scarcely found himself in a congenial atmosphere at
those somewhat hilarious gatherings, where the hardy wielders of the hammer
not only drank port--and plenty of it--but wound up their meal with a
mixture of Scotch ale and soda water, a drink which, as reminiscent of the
"field," was regarded as especially appropriate to geologists. Even after
the meetings, which followed the dinners, they reassembled for suppers, at
which geological dainties, like "pterodactyle pie" figured in the bill of
fare, and fines of bumpers were inflicted on those who talked the

After being present at a fair number of meetings in 1837 and 1838, Darwin's
attendances at the Club fell off to two in 1839, and by 1841 he had ceased
to be a member. In a letter to Lyell on Dec. 2nd, 1841, Leonard Horner
wrote that the day before "At the Council, I had the satisfaction of seeing
Darwin again in his place and looking well. He tried the last evening
meeting, but found it too much, but I hope before the end of the season he
will find himself equal to that also. I hail Darwin's recovery as a vast
gain to science." Darwin's probably last attendance, this time as a guest,
was in 1851, when Horner again wrote to Lyell, "Charles Darwin was at the
Geological Society's Club yesterday, where he had not been for ten years--
remarkably well, and grown quite stout." ("Memoirs of Leonard Horner"
(privately printed), Vol. II. pages 39 and 195.)

It may be interesting to note that at the somewhat less lively dining Club-
-the Philosophical--in the founding of which his friends Lyell and Hooker
had taken so active a part, Darwin found himself more at home, and he was a
frequent attendant--in spite of his residence being at Down--from 1853 to
1864. He even made contributions on scientific questions after these
dinners. In a letter to Hooker he states that he was deeply interested in
the reforms of the Royal Society, which the Club was founded to promote.
He says also that he had arranged to come to town every Club day "and then
my head, I think, will allow me on an average to go to every other meeting.
But it is grievous how often any change knocks me up." ("L.L." II. pages
42, 43.)

Of the years 1837 and 1838 Darwin himself says they were "the most active
ones which I ever spent, though I was occasionally unwell, and so lost some
time...I also went a little into society." ("L.L." I. pages 67, 68.) But
of the four years from 1839 to 1842 he has to confess sadly "I did less
scientific work, though I worked as hard as I could, than during any other
equal length of time in my life. This was owing to frequently recurring
unwellness, and to one long and serious illness." ("L.L." I. page 69.)

Darwin's work at the Geological Society did not by any means engage the
whole of his energies, during the active years 1837 and 1838. In June of
the latter year, leaving town in somewhat bad health, he found himself at
Edinburgh again, and engaged in examining the Salisbury Craigs, in a very
different spirit to that excited by Jameson's discourse. ("L.L." I. page
290.) Proceeding to the Highlands he then had eight days of hard work at
the famous "Parallel Roads of Glen Roy", being favoured with glorious

He says of the writing of the paper on the subject--the only memoir
contributed by Darwin to the Royal Society, to which he had been recently
elected--that it was "one of the most difficult and instructive tasks I was
ever engaged on." The paper extends to 40 quarto pages and is illustrated
by two plates. Though it is full of the records of careful observation and
acute reasoning, yet the theory of marine beaches which he propounded was,
as he candidly admitted in after years ("M.L." II page 188.), altogether
wrong. The alternative lake-theory he found himself unable to accept at
the time, for he could not understand how barriers could be formed at
successive levels across the valleys; and until the following year, when
the existence of great glaciers in the district was proved by the
researches of Agassiz, Buckland and others, the difficulty appeared to him
an insuperable one. Although Darwin said of this paper in after years that
it "was a great failure and I am ashamed of it"--yet he retained his
interest in the question ever afterwards, and he says "my error has been a
good lesson to me never to trust in science to the principle of exclusion."
("M.L." II. pages 171-93.)

Although Darwin had not realised in 1838 that large parts of the British
Islands had been occupied by great glaciers, he had by no means failed
while in South America to recognise the importance of ice-action. His
observations, as recorded in his Journal, on glaciers coming down to the
sea-level, on the west coast of South America, in a latitude corresponding
to a much lower one than that of the British Islands, profoundly interested
geologists; and the same work contains many valuable notes on the boulders
and unstratified beds in South America in which they were included.

But in 1840 Agassiz read his startling paper on the evidence of the former
existence of glaciers in the British Islands, and this was followed by
Buckland's memoir on the same subject. On April 14, 1841, Darwin
contributed to the Geological Society his important paper "On the
Distribution of Erratic Boulders and the Contemporaneous Unstratified
Deposits of South America", a paper full of suggestiveness for those
studying the glacial deposits of this country. It was published in the
"Transactions" in 1842.

The description of traces of glacial action in North Wales, by Buckland,
appears to have greatly excited the interest of Darwin. With Sedgwick he
had, in 1831, worked at the stratigraphy of that district, but neither of
them had noticed the very interesting surface features. ("L.L." I. page
58.) Darwin was able to make a journey to North Wales in June, 1842 (alas!
it was his last effort in field-geology) and as a result he published his
most able and convincing paper on the subject in the September number of
the "Philosophical Magazine" for 1842. Thus the mystery of the bell-stone
was at last solved and Darwin, writing many years afterwards, said "I felt
the keenest delight when I first read of the action of icebergs in
transporting boulders, and I gloried in the progress of Geology." ("L.L."
I. page 41.) To the "Geographical Journal" he had sent in 1839 a note "On
a Rock seen on an Iceberg in 16 deg S. Latitude." For the subject of ice-
action, indeed, Darwin retained the greatest interest to the end of his
life. ("M.L." II. pages 148-71.)

In 1846, Darwin read two papers to the Geological Society "On the dust
which falls on vessels in the Atlantic, and On the Geology of the Falkland
Islands"; in 1848 he contributed a note on the transport of boulders from
lower to higher levels; and in 1862 another note on the thickness of the
Pampean formation, as shown by recent borings at Buenos Ayres. An account
of the "British Fossil Lepadidae" read in 1850, was withdrawn by him.

At the end of 1836 Darwin had settled himself in lodgings in Fitzwilliam
Street, Cambridge, and devoted three months to the work of unpacking his
specimens and studying his collection of rocks. The pencilled notes on the
Manuscript Catalogue in the Sedgwick Museum enable us to realise his mode
of work, and the diligence with which it was carried on. The letters M and
H, indicate the assistance he received from time to time from Professor
Miller, the crystallographer, and from his friend Henslow. Miller not only
measured many of the crystals submitted to him, but evidently taught Darwin
to use the reflecting goniometer himself with considerable success. The
"book of measurements" in which the records were kept, appears to have been
lost, but the pencilled notes in the catalogue show how thoroughly the work
was done. The letter R attached to some of the numbers in the catalogue
evidently refers to the fact that they were submitted to Mr Trenham Reeks
(who analysed some of his specimens) at the Geological Survey quarters in
Craig's Court. This was at a later date when Darwin was writing the
"Volcanic Islands" and "South America".

It was about the month of March, 1837, that Darwin completed this work upon
his rocks, and also the unpacking and distribution of his fossil bones and
other specimens. We have seen that November, 1832, must certainly be
regarded as the date when he FIRST realised the important fact that the
fossil mammals of the Pampean formation were all closely related to the
existing forms in South America; while October, 1835, was, as undoubtedly,
the date when the study of the birds and other forms of life in the several
islands of the Galapagos Islands gave him his SECOND impulse towards
abandoning the prevalent view of the immutability of species. When then in
his pocket-book for 1837 Darwin wrote the often quoted passage: "In July
opened first note-book on Transmutation of Species. Had been greatly
struck from about the month of previous March on character of South
American fossils, and species on Galapagos Archipelago. These facts
(especially latter), origin of all my views" ("L.L." I. page 276.), it is
clear that he must refer, not to his first inception of the idea of
evolution, but to the flood of recollections, the reawakening of his
interest in the subject, which could not fail to result from the sight of
his specimens and the reference to his notes.

Except during the summer vacation, when he was visiting his father and
uncle, and with the latter making his first observations upon the work of
earthworms, Darwin was busy with his arrangements for the publication of
the five volumes of the "Zoology of the 'Beagle'" and in getting the
necessary financial aid from the government for the preparation of the
plates. He was at the same time preparing his "Journal" for publication.
During the years 1837 to 1843, Darwin worked intermittently on the volumes
of Zoology, all of which he edited, while he wrote introductions to those
by Owen and Waterhouse and supplied notes to the others.

Although Darwin says of his Journal that the preparation of the book "was
not hard work, as my MS. Journal had been written with care." Yet from the
time that he settled at 36, Great Marlborough Street in March, 1837, to the
following November he was occupied with this book. He tells us that the
account of his scientific observations was added at this time. The work
was not published till March, 1839, when it appeared as the third volume of
the "Narrative of the Surveying Voyages of H.M. Ships 'Adventure' and
'Beagle' between the years 1826 and 1836". The book was probably a long
time in the press, for there are no less than 20 pages of addenda in small
print. Even in this, its first form, the work is remarkable for its
freshness and charm, and excited a great amount of attention and interest.
In addition to matters treated of in greater detail in his other works,
there are many geological notes of extreme value in this volume, such as
his account of lightning tubes, of the organisms found in dust, and of the
obsidian bombs of Australia.

Having thus got out of hand a number of preliminary duties, Darwin was
ready to set to work upon the three volumes which were designed by him to
constitute "The Geology of the Voyage of the 'Beagle'". The first of these
was to be on "The Structure and Distribution of Coral-reefs". He commenced
the writing of the book on October 5, 1838, and the last proof was
corrected on May 6, 1842. Allowing for the frequent interruptions through
illness, Darwin estimated that it cost him twenty months of hard work.

Darwin has related how his theory of Coral-reefs which was begun in a more
"deductive spirit" than any of his other work, for in 1834 or 1835 it "was
thought out on the west coast of South America, before I had seen a true
coral-reef." ("L.L." I. page 70.) The final chapter in Lyell's second
volume of the "Principles" was devoted to the subject of Coral-reefs, and a
theory was suggested to account for the peculiar phenomena of "atolls."
Darwin at once saw the difficulty of accepting the view that the numerous
and diverse atolls all represent submerged volcanic craters. His own work
had for two years been devoted to the evidence of land movements over great
areas in South America, and thus he was led to announce his theory of
subsidence to account for barrier and encircling reefs as well as atolls.

Fortunately, during his voyage across the Pacific and Indian Oceans, in his
visit to Australia and his twelve days' hard work at Keeling Island, he had
opportunities for putting his theory to the test of observation.

On his return to England, Darwin appears to have been greatly surprised at
the amount of interest that his new theory excited. Urged by Lyell, he
read to the Geological Society a paper on the subject, as we have seen,
with as little delay as possible, but this paper was "withdrawn by
permission of the Council." An abstract of three pages however appeared in
the "Proceedings of the Geological Society". (Vol. II. pages 552-554 (May
31, 1837).) A full account of the observations and the theory was given in
the "Journal" (1839) in the 40 pages devoted to Keeling Island in
particular and to Coral formations generally. ("Journal (1st edition),
pages 439-69.)

It will be readily understood what an amount of labour the book on Coral
reefs cost Darwin when we reflect on the number of charts, sailing
directions, narratives of voyages and other works which, with the friendly
assistance of the authorities at the Admiralty, he had to consult before he
could draw up his sketch of the nature and distribution of the reefs, and
this was necessary before the theory, in all its important bearings, could
be clearly enunciated. Very pleasing is it to read how Darwin, although
arriving at a different conclusion to Lyell, shows, by quoting a very
suggestive passage in the "Principles" (1st edition Vol. II. page 296.),
how the latter only just missed the true solution. This passage is cited,
both in the "Journal" and the volume on Coral-reefs. Lyell, as we have
seen, received the new theory not merely ungrudgingly, but with the utmost

In 1849 Darwin was gratified by receiving the support of Dana, after his
prolonged investigation in connection with the U.S. Exploring Expedition
("M.L." II. pages 226-8.), and in 1874 he prepared a second edition of his
book, in which some objections which had been raised to the theory were
answered. A third edition, edited by Professor Bonney, appeared in 1880,
and a fourth (a reprint of the first edition, with introduction by myself)
in 1890.

Although Professor Semper, in his account of the Pelew Islands, had
suggested difficulties in the acceptance of Darwin's theory, it was not
till after the return of the "Challenger" expedition in 1875 that a rival
theory was propounded, and somewhat heated discussions were raised as to
the respective merits of the two theories. While geologists have, nearly
without exception, strongly supported Darwin's views, the notes of dissent
have come almost entirely from zoologists. At the height of the
controversy unfounded charges of unfairness were made against Darwin's
supporters and the authorities of the Geological Society, but this
unpleasant subject has been disposed of, once for all, by Huxley. ("Essays
upon some Controverted Questions", London, 1892, pages 314-328 and 623-

Darwin's final and very characteristic utterance on the coral-reef
controversy is found in a letter which he wrote to Professor Alexander
Agassiz, May 5th, 1881: less than a year before his death: "If I am
wrong, the sooner I am knocked on the head and annihilated so much the
better. It still seems to me a marvellous thing that there should not have
been much, and long-continued, subsidence in the beds of the great oceans.
I wish that some doubly rich millionaire would take it into his head to
have borings made in some of the Pacific and Indian atolls, and bring home
cores for slicing from a depth of 500 or 600 feet." ("L.L." III. page

Though the "doubly rich millionaire" has not been forthcoming, the energy,
in England, of Professor Sollas, and in New South Wales of Professor
Anderson Stuart served to set on foot a project, which, aided at first by
the British Association for the Advancement of Science, and afterwards
taken up jointly by the Royal Society, the New South Wales Government, and
the Admiralty, has led to the most definite and conclusive results.

The Committee appointed by the Royal Society to carry out the undertaking
included representatives of all the views that had been put forward on the
subject. The place for the experiment was, with the consent of every
member of the Committee, selected by the late Admiral Sir W.J. Wharton--who
was not himself an adherent of Darwin's views--and no one has ventured to
suggest that his selection, the splendid atoll of Funafuti, was not a most
judicious one.

By the pluck and perseverance of Professor Sollas in the preliminary
expedition, and of Professor T. Edgeworth David and his pupils, in
subsequent investigations of the island, the rather difficult piece of work
was brought to a highly satisfactory conclusion. The New South Wales
Government lent boring apparatus and workmen, and the Admiralty carried the
expedition to its destination in a surveying ship which, under Captain (now
Admiral) A. Mostyn Field, made the most complete survey of the atoll and
its surrounding seas that has ever been undertaken in the case of a coral

After some failures and many interruptions, the boring was carried to the
depth of 1114 feet, and the cores obtained were sent to England. Here the
examination of the materials was fortunately undertaken by a zoologist of
the highest repute, Dr G.J. Hinde--who has a wide experience in the study
of organisms by sections--and he was aided at all points by specialists in
the British Museum of Natural History and by other naturalists. Nor were
the chemical and other problems neglected.

The verdict arrived at, after this most exhaustive study of a series of
cores obtained from depths twice as great as that thought necessary by
Darwin, was as follows:--"The whole of the cores are found to be built up
of those organisms which are seen forming coral-reefs near the surface of
the ocean--many of them evidently in situ; and not the slightest indication
could be detected, by chemical or microscopic means, which suggested the
proximity of non-calcareous rocks, even in the lowest portions brought up."

But this was not all. Professor David succeeded in obtaining the aid of a
very skilful engineer from Australia, while the Admiralty allowed Commander
F.C.D. Sturdee to take a surveying ship into the lagoon for further
investigations. By very ingenious methods, and with great perseverance,
two borings were put down in the midst of the lagoon to the depth of nearly
200 feet. The bottom of the lagoon, at the depth of 101 1/2 feet from sea-
level, was found to be covered with remains of the calcareous, green sea-
weed Halimeda, mingled with many foraminifera; but at a depth of 163 feet
from the surface of the lagoon the boring tools encountered great masses of
coral, which were proved from the fragments brought up to belong to species
that live within AT MOST 120 feet from the surface of the ocean, as
admitted by all zoologists. ("The Atoll of Funafuti; Report of the Coral
Reef Committee of the Royal Society", London, 1904.)

Darwin's theory, as is well known, is based on the fact that the
temperature of the ocean at any considerable depth does not permit of the
existence and luxuriant growth of the organisms that form the reefs. He
himself estimated this limit of depth to be from 120 to 130 feet; Dana, as
an extreme, 150 feet; while the recent very prolonged and successful
investigations of Professor Alexander Agassiz in the Pacific and Indian
Oceans lead him also to assign a limiting depth of 150 feet; the EFFECTIVE,
REEF-FORMING CORALS, however, flourishing at a much smaller depth. Mr
Stanley Gardiner gives for the most important reef-forming corals depths
between 30 and 90 feet, while a few are found as low as 120 feet or even
180 feet.

It will thus be seen that the verdict of Funafuti is clearly and
unmistakeably in favour of Darwin's theory. It is true that some
zoologists find a difficulty in realising a slow sinking of parts of the
ocean floor, and have suggested new and alternative explanations: but
geologists generally, accepting the proofs of slow upheaval in some areas--
as shown by the admirable researches of Alexander Agassiz--consider that it
is absolutely necessary to admit that this elevation is balanced by
subsidence in other areas. If atolls and barrier-reefs did not exist we
should indeed be at a great loss to frame a theory to account for their

After finishing his book on Coral-reefs, Darwin made his summer excursion
to North Wales, and prepared his important memoir on the glaciers of that
district: but by October (1842) we find him fairly settled at work upon
the second volume of his "Geology of the 'Beagle'--Geological Observations
on the Volcanic Islands, visited during the Voyage of H.M.S. 'Beagle'".
The whole of the year 1843 was devoted to this work, but he tells his
friend Fox that he could "manage only a couple of hours per day, and that
not very regularly." ("L.L." I. page 321.) Darwin's work on the various
volcanic islands examined by him had given him the most intense pleasure,
but the work of writing the book by the aid of his notes and specimens he
found "uphill work," especially as he feared the book would not be read,
"even by geologists." (Loc. cit.)

As a matter of fact the work is full of the most interesting observations
and valuable suggestions, and the three editions (or reprints) which have
appeared have proved a most valuable addition to geological literature. It
is not necessary to refer to the novel and often very striking discoveries
described in this well-known work. The subsidence beneath volcanic vents,
the enormous denudation of volcanic cones reducing them to "basal wrecks,"
the effects of solfatarric action and the formation of various minerals in
the cavities of rocks--all of these subjects find admirable illustration
from his graphic descriptions. One of the most important discussions in
this volume is that dealing with the "lamination" of lavas as especially
well seen in the rocks of Ascension. Like Scrope, Darwin recognised the
close analogy between the structure of these rocks and those of metamorphic
origin--a subject which he followed out in the volume "Geological
Observations on South America".

Of course in these days, since the application of the microscope to the
study of rocks in thin sections, Darwin's nomenclature and descriptions of
the petrological characters of the lavas appear to us somewhat crude. But
it happened that the "Challenger" visited most of the volcanic islands
described by Darwin, and the specimens brought home were examined by the
eminent petrologist Professor Renard. Renard was so struck with the work
done by Darwin, under disadvantageous conditions, that he undertook a
translation of Darwin's work into French, and I cannot better indicate the
manner in which the book is regarded by geologists than by quoting a
passage from Renard's preface. Referring to his own work in studying the
rocks brought home by the "Challenger" (Renard's descriptions of these
rocks are contained in the "Challenger Reports". Mr Harker is
supplementing these descriptions by a series of petrological memoirs on
Darwin's specimens, the first of which appeared in the "Geological
Magazine" for March, 1907.), he says:

"Je dus, en me livrant a ces recherches, suivre ligne par ligne les divers
chapitres des "Observations geologiques" consacrees aux iles de
l'Atlantique, oblige que j'etais de comparer d'une maniere suivie les
resultats auxquels j'etais conduit avec ceux de Darwin, qui servaient de
controle a mes constatations. Je ne tardai pas a eprouver une vive
admiration pour ce chercheur qui, sans autre appareil que la loupe, sans
autre reaction que quelques essais pyrognostiques, plus rarement quelques
mesures au goniometre, parvenait a discerner la nature des agregats
mineralogiques les plue complexes et les plus varies. Ce coup d'oeil qui
savait embrasser de si vastes horizons, penetre ici profondement tous les
details lithologiques. Avec quelle surete et quelle exactitude la
structure et la composition des roches ne sont'elles pas determinees,
l'origne de ces masses minerales deduite et confirmee par l'etude comparee
des manifestations volcaniques d'autres regions; avec quelle science les
relations entre les faits qu'il decouvre et ceux signales ailleurs par ses
devanciers ne sont'elles pas etablies, et comme voici ebranlees les
hypotheses regnantes, admises sans preuves, celles, par exemple, des
crateres de soulevement et de la differenciation radicale des phenomenes
plutoniques et volcaniques! Ce qui acheve de donner a ce livre un
incomparable merite, ce sont les idees nouvelles qui s'y trouvent en germe
et jetees la comme au hasard ainsi qu'un superflu d'abondance
intellectuelle inepuisable." ("Observations Geologiques sur les Iles
Volcaniques...", Paris, 1902, pages vi., vii.)

While engaged in his study of banded lavas, Darwin was struck with the
analogy of their structure with that of glacier ice, and a note on the
subject, in the form of a letter addressed to Professor J.D. Forbes, was
published in the "Proceedings of the Royal Society of Edinburgh". (Vol.
II. (1844-5), pages 17, 18.)

From April, 1832, to September, 1835, Darwin had been occupied in examining
the coast or making inland journeys in the interior of the South American
continent. Thus while eighteen months were devoted, at the beginning and
end of the voyage to the study of volcanic islands and coral-reefs, no less
than three and a half years were given to South American geology. The
heavy task of dealing with the notes and specimens accumulated during that
long period was left by Darwin to the last. Finishing the "Volcanic
Islands" on February 14th, 1844, he, in July of the same year, commenced
the preparation of two important works which engaged him till near the end
of the year 1846. The first was his "Geological Observations on South
America", the second a recast of his "Journal", published under the short
title of "A Naturalist's Voyage round the World".

The first of these works contains an immense amount of information
collected by the author under great difficulties and not unfrequently at
considerable risk to life and health. No sooner had Darwin landed in South
America than two sets of phenomena powerfully arrested his attention. The
first of these was the occurrence of great masses of red mud containing
bones and shells, which afforded striking evidence that the whole continent
had shared in a series of slow and gradual but often interrupted movements.
The second related to the great masses of crystalline rocks which,
underlying the muds, cover so great a part of the continent. Darwin,
almost as soon as he landed, was struck by the circumstance that the
direction, as shown by his compass, of the prominent features of these
great crystalline rock-masses--their cleavage, master-joints, foliation and
pegmatite veins--was the same as the orientation described by Humboldt
(whose works he had so carefully studied) on the west of the same great

The first five chapters of the book on South America were devoted to
formations of recent date and to the evidence collected on the east and
west coasts of the continent in regard to those grand earth-movements, some
of which could be shown to have been accompanied by earthquake-shocks. The
fossil bones, which had given him the first hint concerning the mutability
of species, had by this time been studied and described by comparative
anatomists, and Darwin was able to elaborate much more fully the important
conclusion that the existing fauna of South America has a close analogy
with that of the period immediately preceding our own.

The remaining three chapters of the book dealt with the metamorphic and
plutonic rocks, and in them Darwin announced his important conclusions
concerning the relations of cleavage and foliation, and on the close
analogy of the latter structure with the banding found in rock-masses of
igneous origin. With respect to the first of these conclusions, he
received the powerful support of Daniel Sharpe, who in the years 1852 and
1854 published two papers on the structure of the Scottish Highlands,
supplying striking confirmation of the correctness of Darwin's views.
Although Darwin's and Sharpe's conclusions were contested by Murchison and
other geologists, they are now universally accepted. In his theory
concerning the origin of foliation, Darwin had been to some extent
anticipated by Scrope, but he supplied many facts and illustrations leading
to the gradual acceptance of a doctrine which, when first enunciated, was
treated with neglect, if not with contempt.

The whole of this volume on South American geology is crowded with the
records of patient observations and suggestions of the greatest value; but,
as Darwin himself saw, it was a book for the working geologist and "caviare
to the general." Its author, indeed, frequently expressed his sense of the
"dryness" of the book; he even says "I long hesitated whether I would
publish it or not," and he wrote to Leonard Horner "I am astonished that
you should have had the courage to go right through my book." ("M.L." II.
page 221.)

Fortunately the second book, on which Darwin was engaged at this time, was
of a very different character. His "Journal", almost as he had written it
on board ship, with facts and observations fresh in his mind, had been
published in 1839 and attracted much attention. In 1845, he says, "I took
much pains in correcting a new edition," and the work which was commenced
in April, 1845, was not finished till August of that year. The volume
contains a history of the voyage with "a sketch of those observations in
Natural History and Geology, which I think will possess some interest for
the general reader." It is not necessary to speak of the merits of this
scientific classic. It became a great favourite with the general public--
having passed through many editions--it was, moreover, translated into a
number of different languages. Darwin was much gratified by these
evidences of popularity, and naively remarks in his "Autobiography", "The
success of this my first literary child tickles my vanity more than that of
any of my other books" ("L.L." I. page 80.)--and this was written after the
"Origin of Species" had become famous!

In Darwin's letters there are many evidences that his labours during these
ten years devoted to the working out of the geological results of the
voyage often made many demands on his patience and indomitable courage.
Most geologists have experience of the contrast between the pleasures felt
when wielding the hammer in the field, and the duller labour of plying the
pen in the study. But in Darwin's case, innumerable interruptions from
sickness and other causes, and the oft-deferred hope of reaching the end of
his task were not the only causes operating to make the work irksome. The
great project, which was destined to become the crowning achievement of his
life, was now gradually assuming more definite shape, and absorbing more of
his time and energies.

Nevertheless, during all this period, Darwin so far regarded his geological
pursuits as his PROPER "work," that attention to other matters was always
spoken of by him as "indulging in idleness." If at the end of this period
the world had sustained the great misfortune of losing Darwin by death
before the age of forty--and several times that event seemed only too
probable--he might have been remembered only as a very able geologist of
most advanced views, and a traveller who had written a scientific narrative
of more than ordinary excellence!

The completion of the "Geology of the 'Beagle'" and the preparation of a
revised narrative of the voyage mark the termination of that period of
fifteen years of Darwin's life during which geological studies were his
principal occupation. Henceforth, though his interest in geological
questions remained ever keen, biological problems engaged more and more of
his attention to the partial exclusion of geology.

The eight years from October, 1846, to October, 1854, were mainly devoted
to the preparation of his two important monographs on the recent and fossil
Cirripedia. Apart from the value of his description of the fossil forms,
this work of Darwin's had an important influence on the progress of
geological science. Up to that time a practice had prevailed for the
student of a particular geological formation to take up the description of
the plant and animal remains in it--often without having anything more than
a rudimentary knowledge of the living forms corresponding to them. Darwin
in his monograph gave a very admirable illustration of the enormous
advantage to be gained--alike for biology and geology--by undertaking the
study of the living and fossil forms of a natural group of organisms in
connection with one another. Of the advantage of these eight years of work
to Darwin himself, in preparing for the great task lying before him, Huxley
has expressed a very strong opinion indeed. ("L.L." II. pages 247-48.)

But during these eight years of "species work," Darwin found opportunities
for not a few excursions into the field of geology. He occasionally
attended the Geological Society, and, as we have already seen, read several
papers there during this period. His friend, Dr Hooker, then acting as
botanist to the Geological Survey, was engaged in studying the
Carboniferous flora, and many discussions on Palaezoic plants and on the
origin of coal took place at this period. On this last subject he felt the
deepest interest and told Hooker, "I shall never rest easy in Down
churchyard without the problem be solved by some one before I die."
("M.L." I. pages 63, 64.)

As at all times, conversations and letters with Lyell on every branch of
geological science continued with unabated vigour, and in spite of the
absorbing character of the work on the Cirripedes, time was found for all.
In 1849 his friend Herschel induced him to supply a chapter of forty pages
on Geology to the Admiralty "Manual of Scientific Inquiry" which he was
editing. This is Darwin's single contribution to books of an "educational"
kind. It is remarkable for its clearness and simplicity and attention to
minute details. It may be read by the student of Darwin's life with much
interest, for the directions he gives to an explorer are without doubt
those which he, as a self-taught geologist, proved to be serviceable during
his life on the "Beagle".

On the completion of the Cirripede volumes, in 1854, Darwin was able to
grapple with the immense pile of MS. notes which he had accumulated on the
species question. The first sketch of 35 pages (1842), had been enlarged
in 1844 into one of 230 pages ([The first draft of the "Origin" is being
prepared for Press by Mr Francis Darwin and will be published by the
Cambridge University Press this year (1909). A.C.S.]); but in 1856 was
commenced the work (never to be completed) which was designed on a scale
three or four times more extensive than that on which the "Origin of
Species" was in the end written.

In drawing up those two masterly chapters of the "Origin", "On the
Imperfection of the Geological Record," and "On the Geological Succession
of Organic Beings", Darwin had need of all the experience and knowledge he
had been gathering during thirty years, the first half of which had been
almost wholly devoted to geological study. The most enlightened geologists
of the day found much that was new, and still more that was startling from
the manner of its presentation, in these wonderful essays. Of Darwin's own
sense of the importance of the geological evidence in any presentation of
his theory a striking proof will be found in a passage of the touching
letter to his wife, enjoining the publication of his sketch of 1844. "In
case of my sudden death," he wrote, "...the editor must be a geologist as
well as a naturalist." ("L.L." II. pages 16, 17.)

In spite of the numerous and valuable palaeontological discoveries made
since the publication of "The Origin of Species", the importance of the
first of these two geological chapters is as great as ever. It still
remains true that "Those who believe that the geological record is in any
degree perfect, will at once reject the theory"--as indeed they must reject
any theory of evolution. The striking passage with which Darwin concludes
this chapter--in which he compares the record of the rocks to the much
mutilated volumes of a human history--remains as apt an illustration as it
did when first written.

And the second geological chapter, on the Succession of Organic Beings--
though it has been strengthened in a thousand ways, by the discoveries
concerning the pedigrees of the horse, the elephant and many other aberrant
types, though new light has been thrown even on the origin of great groups
like the mammals, and the gymnosperms, though not a few fresh links have
been discovered in the chains of evidence, concerning the order of
appearance of new forms of life--we would not wish to have re-written.
Only the same line of argument could be adopted, though with innumerable
fresh illustrations. Those who reject the reasonings of this chapter,
neither would they be persuaded if a long and complete succession of
"ancestral forms" could rise from the dead and pass in procession before

Among the geological discussions, which so frequently occupied Darwin's
attention during the later years of his life, there was one concerning
which his attitude seemed somewhat remarkable--I allude to his views on
"the permanence of Continents and Ocean-basins." In a letter to Mr Mellard
Reade, written at the end of 1880, he wrote: "On the whole, I lean to the
side that the continents have since Cambrian times occupied approximately
their present positions. But, as I have said, the question seems a
difficult one, and the more it is discussed the better." ("M.L." II. page
147.) Since this was written, the important contribution to the subject by
the late Dr W.T. Blanford (himself, like Darwin, a naturalist and
geologist) has appeared in an address to the Geological Society in 1890;
and many discoveries, like that of Dr Woolnough in Fiji, have led to
considerable qualifications of the generalisation that all the islands in
the great ocean are wholly of volcanic or coral origin.

I remember once expressing surprise to Darwin that, after the views which
he had originated concerning the existence of areas of elevation and others
of subsidence in the Pacific Ocean, and in face of the admitted difficulty
of accounting for the distribution of certain terrestrial animals and
plants, if the land and sea areas had been permanent in position, he still
maintained that theory. Looking at me with a whimsical smile, he said: "I
have seen many of my old friends make fools of themselves, by putting
forward new theoretical views or revising old ones, AFTER THEY WERE SIXTY
YEARS OF AGE; so, long ago, I determined that on reaching that age I would
write nothing more of a speculative character."

Though Darwin's letters and conversations on geology during these later
years were the chief manifestations of the interest he preserved in his
"old love," as he continued to call it, yet in the sunset of that active
life a gleam of the old enthusiasm for geology broke forth once more.
There can be no doubt that Darwin's inability to occupy himself with field-
work proved an insuperable difficulty to any attempt on his part to resume
active geological research. But, as is shown by the series of charming
volumes on plant-life, Darwin had found compensation in making patient and
persevering experiment take the place of enterprising and exact
observation; and there was one direction in which he could indulge the "old
love" by employment of the new faculty.

We have seen that the earliest memoir written by Darwin, which was
published in full, was a paper "On the Formation of Mould" which was read
at the Geological Society on November 1st, 1837, but did not appear in the
"Transactions" of the Society till 1840, where it occupied four and a half
quarto pages, including some supplementary matter, obtained later, and a
woodcut. This little paper was confined to observations made in his
uncle's fields in Staffordshire, where burnt clay, cinders, and sand were
found to be buried under a layer of black earth, evidently brought from
below by earthworms, and to a recital of similar facts from Scotland
obtained through the agency of Lyell. The subsequent history of Darwin's
work on this question affords a striking example of the tenacity of purpose
with which he continued his enquiries on any subject that interested him.

In 1842, as soon as he was settled at Down, he began a series of
observations on a foot-path and in his fields, that continued with
intermissions during his whole life, and he extended his enquiries from
time to time to the neighbouring parks of Knole and Holwood. In 1844 we
find him making a communication to the "Gardener's Chronicle" on the
subject. About 1870, his attention to the question was stimulated by the
circumstance that his niece (Miss L. Wedgwood) undertook to collect and
weigh the worm-casts thrown up, during a whole year, on measured squares
selected for the purpose, at Leith Hill Place. He also obtained
information from Professor Ramsay concerning observations made by him on a
pavement near his house in 1871. Darwin at this time began to realise the
great importance of the action of worms to the archaeologist. At an
earlier date he appears to have obtained some information concerning
articles found buried on the battle-field of Shrewsbury, and the old Roman
town of Uriconium, near his early home; between 1871 and 1878 Mr
(afterwards Lord) Farrer carried on a series of investigations at the Roman
Villa discovered on his land at Abinger; Darwin's son William examined for
his father the evidence at Beaulieu Abbey, Brading, Stonehenge and other
localities in the neighbourhood of his home; his sons Francis and Horace
were enlisted to make similar enquiries at Chideock and Silchester; while
Francis Galton contributed facts noticed in his walks in Hyde Park. By
correspondence with Fritz Muller and Dr Ernst, Darwin obtained information
concerning the worm-casts found in South America; from Dr Kreft those of
Australia; and from Mr Scott and Dr (afterwards Sir George) King, those of
India; the last-named correspondent also supplied him with much valuable
information obtained in the South of Europe. Help too was obtained from
the memoirs on Earthworms published by Perrier in 1874 and van Hensen in
1877, while Professor Ray Lankester supplied important facts with regard to
their anatomy.

When therefore the series of interesting monographs on plant-life had been
completed, Darwin set to work in bringing the information that he had
gradually accumulated during forty-four years to bear on the subject of his
early paper. He also utilised the skill and ingenuity he had acquired in
botanical work to aid in the elucidation of many of the difficulties that
presented themselves. I well remember a visit which I paid to Down at this
period. At the side of the little study stood flower-pots containing earth
with worms, and, without interrupting our conversation, Darwin would from
time to time lift the glass plate covering a pot to watch what was going
on. Occasionally, with a humorous smile, he would murmur something about a
book in another room, and slip away; returning shortly, without the book
but with unmistakeable signs of having visited the snuff-jar outside.
After working about a year at the worms, he was able at the end of 1881 to
publish the charming little book--"The Formation of Vegetable Mould through
the Action of Worms, with Observations on their Habits". This was the last
of his books, and its reception by reviewers and the public alike afforded
the patient old worker no little gratification. Darwin's scientific
career, which had begun with geological research, most appropriately ended
with a return to it.

It has been impossible to sketch the origin and influence of Darwin's
geological work without, at almost every step, referring to the part played
by Lyell and the "Principles of Geology". Haeckel, in the chapters on
Lyell and Darwin in his "History of Creation", and Huxley in his striking
essay "On the Reception of the Origin of Species" ("L.L." II. pages 179-
204.) have both strongly insisted on the fact that the "Origin" of Darwin
was a necessary corollary to the "Principles" of Lyell.

It is true that, in an earlier essay, Huxley had spoken of the doctrine of
Uniformitarianism as being, in a certain sense, opposed to that of
Evolution (Huxley's Address to the Geological Society, 1869. "Collected
Essays", Vol. VIII. page 305, London, 1896.); but in his later years he
took up a very different and more logical position, and maintained that
"Consistent uniformitarianism postulates evolution as much in the organic
as in the inorganic world. The origin of a new species by other than
ordinary agencies would be a vastly greater 'catastrophe' than any of those
which Lyell success fully eliminated from sober geological speculation."
("L.L." II. page 190.)

Huxley's admiration for the "Principles of Geology", and his conviction of
the greatness of the revolution of thought brought about by Lyell, was
almost as marked as in the case of Darwin himself. (See his Essay on
"Science and Pseudo Science". "Collected Essays", Vol. V. page 90, London,
1902.) He felt, however, as many others have done, that in one respect the
very success of Lyell's masterpiece has been the reason why its originality
and influence have not been so fully recognised as they deserved to be.
Written as the book was before its author had arrived at the age of thirty,
no less than eleven editions of the "Principles" were called for in his
lifetime. With the most scrupulous care, Lyell, devoting all his time and
energies to the task of collecting and sifting all evidence bearing on the
subjects of his work, revised and re-revised it; and as in each edition,
eliminations, modifications, corrections, and additions were made, the
book, while it increased in value as a storehouse of facts, lost much of
its freshness, vigour and charm as a piece of connected reasoning.

Darwin undoubtedly realised this when he wrote concerning the "Principles",
"the first edition, my old true love, which I never deserted for the later
editions." ("M.L." II. page 222.) Huxley once told me that when, in later
life, he read the first edition, he was both surprised and delighted,
feeling as if it were a new book to him. (I have before me a letter which
illustrates this feeling on Huxley's part. He had lamented to me that he
did not possess a copy of the first edition of the "Principles", when,
shortly afterwards, I picked up a dilapidated copy on a bookstall; this I
had bound and sent to my old teacher and colleague. His reply is

October 8, 1884.

My Dear Judd,

You could not have made me a more agreeable present than the copy of the
first edition of Lyell, which I find on my table. I have never been able
to meet with the book, and your copy is, as the old woman said of her
Bible, "the best of books in the best of bindings."

Ever yours sincerely,

T.H. Huxley.

I cannot refrain from relating an incident which very strikingly
exemplifies the affection for one another felt by Lyell and Huxley. In his
last illness, when confined to his bed, Lyell heard that Huxley was to
lecture at the Royal Institution on the "Results of the 'Challenger'
expedition": he begged me to attend the lecture and bring him an account
of it. Happening to mention this to Huxley, he at once undertook to go to
Lyell in my place, and he did so on the morning following his lecture. I
shall never forget the look of gratitude on the face of the invalid when he
told me, shortly afterwards, how Huxley had sat by his bedside and
"repeated the whole lecture to him.")

Darwin's generous nature seems often to have made him experience a fear
lest he should do less than justice to his "dear old master," and to the
influence that the "Principles of Geology" had in moulding his mind. In
1845 he wrote to Lyell, "I have long wished, not so much for your sake, as
for my own feelings of honesty, to acknowledge more plainly than by mere
reference, how much I geologically owe you. Those authors, however, who
like you, educate people's minds as well as teach them special facts, can
never, I should think, have full justice done them except by posterity, for
the mind thus insensibly improved can hardly perceive its own upward
ascent." ("L.L." I. pages 337-8.) In another letter, to Leonard Horner,
he says: "I always feel as if my books came half out of Lyell's brain, and
that I never acknowledge this sufficiently." ("M.L." II. page 117.)
Darwin's own most favourite book, the "Narrative of the Voyage", was
dedicated to Lyell in glowing terms; and in the "Origin of Species" he
wrote of "Lyell's grand work on the "Principles of Geology", which the
future historian will recognise as having produced a revolution in Natural
Science." "What glorious good that work has done" he fervently exclaims on
another occasion. ("L.L." I. page 342.)

To the very end of his life, as all who were in the habit of talking with
Darwin can testify, this sense of his indebtedness to Lyell remained with
him. In his "Autobiography", written in 1876, the year after Lyell's
death, he spoke in the warmest terms of the value to him of the
"Principles" while on the voyage and of the aid afforded to him by Lyell on
his return to England. ("L.L." I. page 62.) But the year before his own
death, Darwin felt constrained to return to the subject and to place on
record a final appreciation--one as honourable to the writer as it is to
his lost friend:

"I saw more of Lyell than of any other man, both before and after my
marriage. His mind was characterised, as it appeared to me, by clearness,
caution, sound judgment, and a good deal of originality. When I made any
remark to him on Geology, he never rested until he saw the whole case
clearly, and often made me see it more clearly than I had done before. He
would advance all possible objections to my suggestion, and even after
these were exhausted would remain long dubious. A second characteristic
was his hearty sympathy with the work of other scientific men...His delight
in science was ardent, and he felt the keenest interest in the future
progress of mankind. He was very kind-hearted...His candour was highly
remarkable. He exhibited this by becoming a convert to the Descent theory,
though he had gained much fame by opposing Lamarck's views, and this after
he had grown old."

italics are mine.)

Those who knew Lyell intimately will recognise the truth of the portrait
drawn by his dearest friend, and I believe that posterity will endorse
Darwin's deliberate verdict concerning the value of his labours.

It was my own good fortune, to be brought into close contact with these two
great men during the later years of their life, and I may perhaps be
permitted to put on record the impressions made upon me during friendly
intercourse with both.

In some respects, there was an extraordinary resemblance in their modes and
habits of thought, between Lyell and Darwin; and this likeness was also
seen in their modesty, their deference to the opinion of younger men, their
enthusiasm for science, their freedom from petty jealousies and their
righteous indignation for what was mean and unworthy in others. But yet
there was a difference. Both Lyell and Darwin were cautious, but perhaps
Lyell carried his caution to the verge of timidity. I think Darwin
possessed, and Lyell lacked, what I can only describe by the theological
term, "faith--the substance of things hoped for, the evidence of things not
seen." Both had been constrained to feel that the immutability of species
could not be maintained. Both, too, recognised the fact that it would be
useless to proclaim this conviction, unless prepared with a satisfactory
alternative to what Huxley called "the Miltonic hypothesis." But Darwin's
conviction was so far vital and operative that it sustained him while
working unceasingly for twenty-two years in collecting evidence bearing on
the question, till at last he was in the position of being able to justify
that conviction to others.

And yet Lyell's attitude--and that of Hooker, which was very similar--
proved of inestimable service to science, as Darwin often acknowledged.
One of the greatest merits of the "Origin of Species" is that so many
difficulties and objections are anticipated and fairly met; and this was to
a great extent the result of the persistent and very candid--if always
friendly--criticism of Lyell and Hooker.

I think the divergence of mental attitude in Lyell and Darwin must be
attributed to a difference in temperament, the evidence of which sometimes
appears in a very striking manner in their correspondence. Thus in 1838,
while they were in the thick of the fight with the Catastrophists of the
Geological Society, Lyell wrote characteristically: "I really find, when
bringing up my Preliminary Essays in "Principles" to the science of the
present day, so far as I know it, that the great outline, and even most of
the details, stand so uninjured, and in many cases they are so much
strengthened by new discoveries, especially by yours, that we may begin to
hope that the great principles there insisted on will stand the test of new
discoveries." (Lyell's "Life, Letters and Journals", Vol. II. page 44.)
To which the more youthful and impetuous Darwin replies: "BEGIN TO HOPE:
why the POSSIBILITY of a doubt has never crossed my mind for many a day.
This may be very unphilosophical, but my geological salvation is staked on
it...it makes me quite indignant that you should talk of HOPING." ("L.L."
I. page 296.)

It was not only Darwin's "geological salvation" that was at stake, when he
surrendered himself to his enthusiasm for an idea. To his firm faith in
the doctrine of continuity we owe the "Origin of Species"; and while Darwin
became the "Paul" of evolution, Lyell long remained the "doubting Thomas."

Many must have felt like H.C. Watson when he wrote: "How could Sir C.
Lyell...for thirty years read, write, and think, on the subject of species
AND THEIR SUCCESSION, and yet constantly look down the wrong road!" ("L.L."
II. page 227.) Huxley attributed this hesitation of Lyell to his "profound
antipathy" to the doctrine of the "pithecoid origin of man." ("L.L." II.
page 193.) Without denying that this had considerable influence (and those
who knew Lyell and his great devotion to his wife and her memory, are aware
that he and she felt much stronger convictions concerning such subjects as
the immortality of the soul than Darwin was able to confess to) yet I think
Darwin had divined the real characteristics of his friend's mind, when he
wrote: "He would advance all possible objections...AND EVEN AFTER THESE

Very touching indeed was the friendship maintained to the end between these
two leaders of thought--free as their intercourse was from any smallest
trace of self-seeking or jealousy. When in 1874 I spent some time with
Lyell in his Forfarshire home, a communication from Darwin was always an
event which made a "red-letter day," as Lyell used to say; and he gave me
many indications in his conversation of how strongly he relied upon the
opinion of Darwin--more indeed than on the judgment of any other man--this
confidence not being confined to questions of science, but extending to
those of morals, politics, and religion.

I have heard those who knew Lyell only slightly, speak of his manners as
cold and reserved. His complete absorption in his scientific work, coupled
with extreme short-sightedness, almost in the end amounting to blindness,
may have permitted those having but a casual acquaintance with him to
accept such a view. But those privileged to know him intimately recognised
the nobleness of his character and can realise the justice and force of
Hooker's words when he heard of his death: "My loved, my best friend, for
well nigh forty years of my life. The most generous sharer of my own and
my family's hopes, joys and sorrows, whose affection for me was truly that
of a father and brother combined."

But the strongest of all testimonies to the grandeur of Lyell's character
is the lifelong devotion to him of such a man as Darwin. Before the two
met, we find Darwin constantly writing of facts and observations that he
thinks "will interest Mr Lyell"; and when they came together the mutual
esteem rapidly ripened into the warmest affection. Both having the
advantage of a moderate independence, permitting of an entire devotion of
their lives to scientific research, they had much in common, and the elder
man--who had already achieved both scientific and literary distinction--was
able to give good advice and friendly help to the younger one. The warmth
of their friendship comes out very strikingly in their correspondence.
When Darwin first conceived the idea of writing a book on the "species
question," soon after his return from the voyage, it was "by following the
example of Lyell in Geology" that he hoped to succeed ("L.L." I. page 83.);
when in 1844, Darwin had finished his first sketch of the work, and,
fearing that his life might not be spared to complete his great
undertaking, committed the care of it in a touching letter to his wife, it
was his friend Lyell whom he named as her adviser and the possible editor
of the book ("L.L." II. pages 17-18.); it was Lyell who, in 1856, induced
Darwin to lay the foundations of a treatise ("L.L." I. page 84.) for which
the author himself selected the "Principles" as his model; and when the
dilemma arose from the receipt of Wallace's essay, it was to Lyell jointly
with Hooker that Darwin turned, not in vain, for advice and help.

During the later years of his life, I never heard Darwin allude to his lost
friend--and he did so very often--without coupling his name with some term
of affection. For a brief period, it is true, Lyell's excessive caution
when the "Origin" was published, seemed to try even the patience of Darwin;
but when "the master" was at last able to declare himself fully convinced,
he was the occasion of more rejoicing on the part of Darwin, than any other
convert to his views. The latter was never tired of talking of Lyell's
"magnanimity" and asserted that, "To have maintained in the position of a
master, one side of a question for thirty years, and then deliberately give
it up, is a fact to which I much doubt whether the records of science offer
a parallel." ("L.L." II. pages 229-30.)

Of Darwin himself, I can safely affirm that I never knew anyone who had met
him, even for the briefest period, who was not charmed by his personality.
Who could forget the hearty hand-grip at meeting, the gentle and lingering
pressure of the palm at parting, and above all that winning smile which
transformed his countenance--so as to make portraits, and even photographs,
seem ever afterwards unsatisfying! Looking back, one is indeed tempted to
forget the profoundness of the philosopher, in recollection of the
loveableness of the man.


Honorary Fellow of Christ's College, Cambridge.

My father's interest in plants was of two kinds, which may be roughly
distinguished as EVOLUTIONARY and PHYSIOLOGICAL. Thus in his purely
evolutionary work, for instance in "The Origin of Species" and in his book
on "Variation under Domestication", plants as well as animals served as
material for his generalisations. He was largely dependent on the work of
others for the facts used in the evolutionary work, and despised himself
for belonging to the "blessed gang" of compilers. And he correspondingly
rejoiced in the employment of his wonderful power of observation in the
physiological problems which occupied so much of his later life. But
inasmuch as he felt evolution to be his life's work, he regarded himself as
something of an idler in observing climbing plants, insectivorous plants,
orchids, etc. In this physiological work he was to a large extent urged on
by his passionate desire to understand the machinery of all living things.
But though it is true that he worked at physiological problems in the
naturalist's spirit of curiosity, yet there was always present to him the
bearing of his facts on the problem of evolution. His interests,
physiological and evolutionary, were indeed so interwoven that they cannot
be sharply separated. Thus his original interest in the fertilisation of
flowers was evolutionary. "I was led" ("Life and Letters", I. page 90.),
he says, "to attend to the cross-fertilisation of flowers by the aid of
insects, from having come to the conclusion in my speculations on the
origin of species, that crossing played an important part in keeping
specific forms constant." In the same way the value of his experimental
work on heterostyled plants crystalised out in his mind into the conclusion
that the product of illegitimate unions are equivalent to hybrids--a
conclusion of the greatest interest from an evolutionary point of view.
And again his work "Cross and Self Fertilisation" may be condensed to a
point of view of great importance in reference to the meaning and origin of
sexual reproduction. (See Professor Goebel's article in the present

The whole of his physiological work may be looked at as an illustration of
the potency of his theory as an "instrument for the extension of the realm
of natural knowledge." (Huxley in Darwin's "Life and Letters." II. page

His doctrine of natural selection gave, as is well known, an impulse to the
investigation of the use of organs--and thus created the great school of
what is known in Germany as Biology--a department of science for which no
English word exists except the rather vague term Natural History. This was
especially the case in floral biology, and it is interesting to see with
what hesitation he at first expressed the value of his book on Orchids
("Life and Letters", III. page 254.), "It will perhaps serve to illustrate
how Natural History may be worked under the belief of the modification of
species" (1861). And in 1862 he speaks (Loc. cit.) more definitely of the
relation of his work to natural selection: "I can show the meaning of some
of the apparently meaningless ridges (and) horns; who will now venture to
say that this or that structure is useless?" It is the fashion now to
minimise the value of this class of work, and we even find it said by a
modern writer that to inquire into the ends subserved by organs is not a
scientific problem. Those who take this view surely forget that the
structure of all living things is, as a whole, adaptive, and that a
knowledge of how the present forms come to be what they are includes a
knowledge of why they survived. They forget that the SUMMATION of
variations on which divergence depends is under the rule of the environment
considered as a selective force. They forget that the scientific study of
the interdependence of organisms is only possible through a knowledge of
the machinery of the units. And that, therefore, the investigation of such
widely interesting subjects as extinction and distribution must include a
knowledge of function. It is only those who follow this line of work who
get to see the importance of minute points of structure and understand as
my father did even in 1842, as shown in his sketch of the "Origin" (Now
being prepared for publication.), that every grain of sand counts for
something in the balance. Much that is confidently stated about the
uselessness of different organs would never have been written if the
naturalist spirit were commoner nowadays. This spirit is strikingly shown
in my father's work on the movements of plants. The circumstance that
botanists had not, as a class, realised the interest of the subject
accounts for the fact that he was able to gather such a rich harvest of
results from such a familiar object as a twining plant. The subject had
been investigated by H. von Mohl, Palm, and Dutrochet, but they failed not
only to master the problem but (which here concerns us) to give the
absorbing interest of Darwin's book to what they discovered.

His work on climbing plants was his first sustained piece of work on the
physiology of movement, and he remarks in 1864: "This has been new sort of
work for me." ("Life and Letters", III. page 315. He had, however, made a
beginning on the movements of Drosera.) He goes on to remark with
something of surprise, "I have been pleased to find what a capital guide
for observations a full conviction of the change of species is."

It was this point of view that enabled him to develop a broad conception of
the power of climbing as an adaptation by means of which plants are enabled
to reach the light. Instead of being compelled to construct a stem of
sufficient strength to stand alone, they succeed in the struggle by making
use of other plants as supports. He showed that the great class of
tendril- and root-climbers which do not depend on twining round a pole,
like a scarlet-runner, but on attaching themselves as they grow upwards,
effect an economy. Thus a Phaseolus has to manufacture a stem three feet
in length to reach a height of two feet above the ground, whereas a pea
"which had ascended to the same height by the aid of its tendrils, was but
little longer than the height reached." ("Climbing Plants" (2nd edition
1875), page 193.)

Thus he was led on to the belief that TWINING is the more ancient form of
climbing, and that tendril-climbers have been developed from twiners. In
accordance with this view we find LEAF-CLIMBERS, which may be looked on as
incipient tendril-bearers, occurring in the same genera with simple
twiners. (Loc. cit. page 195.) He called attention to the case of
Maurandia semperflorens in which the young flower-stalks revolve
spontaneously and are sensitive to a touch, but neither of these qualities
is of any perceptible value to the species. This forced him to believe
that in other young plants the rudiments of the faculty needed for twining
would be found--a prophecy which he made good in his "Power of Movement"
many years later.

In "Climbing Plants" he did little more than point out the remarkable fact
that the habit of climbing is widely scattered through the vegetable
kingdom. Thus climbers are to be found in 35 out of the 59 Phanerogamic
Alliances of Lindley, so that "the conclusion is forced on our minds that
the capacity of revolving (If a twining plant, e.g. a hop, is observed
before it has begun to ascend a pole, it will be noticed that, owing to the
curvature of the stem, the tip is not vertical but hangs over in a roughly
horizontal position. If such a shoot is watched it will be found that if,
for instance, it points to the north at a given hour, it will be found
after a short interval pointing north-east, then east, and after about two
hours it will once more be looking northward. The curvature of the stem
depends on one side growing quicker than the opposite side, and the
revolving movement, i.e. circumnutation, depends on the region of quickest
growth creeping gradually round the stem from south through west to south
again. Other plants, e.g. Phaseolus, revolve in the opposite direction.),
on which most climbers depend, is inherent, though undeveloped, in almost
every plant in the vegetable kingdom." ("Climbing Plants", page 205.)

In the "Origin" (Edition I. page 427, Edition VI. page 374.) Darwin speaks
of the "apparent paradox, that the very same characters are analogical when
one class or order is compared with another, but give true affinities when
the members of the same class or order are compared one with another." In
this way we might perhaps say that the climbing of an ivy and a hop are
analogical; the resemblance depending on the adaptive result rather than on
community of blood; whereas the relation between a leaf-climber and a true
tendril-bearer reveals descent. This particular resemblance was one in
which my father took especial delight. He has described an interesting
case occurring in the Fumariaceae. ("Climbing Plants", page 195.) "The
terminal leaflets of the leaf-climbing Fumaria officinalis are not smaller
than the other leaflets; those of the leaf-climbing Adlumia cirrhosa are
greatly reduced; those of Corydalis claviculata (a plant which may be
indifferently called a leaf-climber or a tendril-bearer) are either reduced
to microscopical dimensions or have their blades wholly aborted, so that
this plant is actually in a state of transition; and finally in the
Dicentra the tendrils are perfectly characterized."

It is a remarkable fact that the quality which, broadly speaking, forms the
basis of the climbing habit (namely revolving nutation, otherwise known as
circumnutation) subserves two distinct ends. One of these is the finding
of a support, and this is common to twiners and tendrils. Here the value
ends as far as tendril-climbers are concerned, but in twiners Darwin
believed that the act of climbing round a support is a continuation of the
revolving movement (circumnutation). If we imagine a man swinging a rope
round his head and if we suppose the rope to strike a vertical post, the
free end will twine round it. This may serve as a rough model of twining
as explained in the "Movements and Habits of Climbing Plants". It is on
these points--the nature of revolving nutation and the mechanism of
twining--that modern physiologists differ from Darwin. (See the discussion
in Pfeffer's "The Physiology of Plants" Eng. Tr. (Oxford, 1906), III. page
34, where the literature is given. Also Jost, "Vorlesungen uber
Pflanzenphysiologie", page 562, Jena, 1904.)

Their criticism originated in observations made on a revolving shoot which
is removed from the action of gravity by keeping the plant slowly rotating
about a horizontal axis by means of the instrument known as a klinostat.
Under these conditions circumnutation becomes irregular or ceases
altogether. When the same experiment is made with a plant which has twined
spirally up a stick, the process of climbing is checked and the last few
turns become loosened or actually untwisted. From this it has been argued
that Darwin was wrong in his description of circumnutation as an automatic
change in the region of quickest growth. When the free end of a revolving
shoot points towards the north there is no doubt that the south side has
been elongating more than the north; after a time it is plain from the
shoot hanging over to the east that the west side of the plant has grown
most, and so on. This rhythmic change of the position of the region of
greatest growth Darwin ascribes to an unknown internal regulating power.
Some modern physiologists, however, attempt to explain the revolving
movement as due to a particular form of sensitiveness to gravitation which
it is not necessary to discuss in detail in this place. It is sufficient
for my purpose to point out that Darwin's explanation of circumnutation is
not universally accepted. Personally I believe that circumnutation is
automatic--is primarily due to internal stimuli. It is however in some way
connected with gravitational sensitiveness, since the movement normally
occurs round a vertical line. It is not unnatural that, when the plant has
no external stimulus by which the vertical can be recognised, the revolving
movement should be upset.

Very much the same may be said of the act of twining, namely that most
physiologists refuse to accept Darwin's view (above referred to) that
twining is the direct result of circumnutation. Everyone must allow that
the two phenomena are in some way connected, since a plant which
circumnutates clockwise, i.e. with the sun, twines in the same direction,
and vice versa. It must also be granted that geotropism has a bearing on
the problem, since all plants twine upwards, and cannot twine along a
horizontal support. But how these two factors are combined, and whether
any (and if so what) other factors contribute, we cannot say. If we give
up Darwin's explanation, we must at the same time say with Pfeffer that
"the causes of twining are...unknown." ("The Physiology of Plants", Eng.
Tr. (Oxford, 1906), III. page 37.)

Let us leave this difficult question and consider some other points made
out in the progress of the work on climbing plants. One result of what he
called his "niggling" ("Life and Letters", III. page 312.) work on tendrils
was the discovery of the delicacy of their sense of touch, and the rapidity
of their movement. Thus in a passion-flower tendril, a bit of platinum
wire weighing 1.2 mg. produced curvature ("Climbing Plants", page 171.), as
did a loop of cotton weighing 2 mg. Pfeffer ("Untersuchungen a.d. Bot.
Inst. z. Tubingen", Bd. I. 1881-85, page 506.), however, subsequently found
much greater sensitiveness: thus the tendril of Sicyos angulatus reacted
to 0.00025 mg., but this only occurred when the delicate rider of
cottonwool fibre was disturbed by the wind. The same author expanded and
explained in a most interesting way the meaning of Darwin's observation
that tendrils are not stimulated to movement by drops of water resting on
them. Pfeffer showed that DIRTY water containing minute particles of clay
in suspension acts as a stimulus. He also showed that gelatine acts like
pure water; if a smooth glass rod is coated with a 10 per cent solution of
gelatine and is then applied to a tendril, no movement occurs in spite of
the fact that the gelatine is solid when cold. Pfeffer ("Physiology", Eng.
Tr. III. page 52. Pfeffer has pointed out the resemblance between the
contact irritability of plants and the human sense of touch. Our skin is
not sensitive to uniform pressure such as is produced when the finger is
dipped into mercury (Tubingen "Untersuchungen", I. page 504.) generalises
the result in the statement that the tendril has a special form of
irritability and only reacts to "differences of pressure or variations of
pressure in contiguous...regions." Darwin was especially interested in
such cases of specialised irritability. For instance in May, 1864, he
wrote to Asa Gray ("Life and Letters", III. page 314.) describing the
tendrils of Bignonia capreolata, which "abhor a simple stick, do not much
relish rough bark, but delight in wool or moss." He received, from Gray,
information as to the natural habitat of the species, and finally concluded
that the tendrils "are specially adapted to climb trees clothed with
lichens, mosses, or other such productions." ("Climbing Plants", page

Tendrils were not the only instance discovered by Darwin of delicacy of
touch in plants. In 1860 he had already begun to observe Sundew (Drosera),
and was full of astonishment at its behaviour. He wrote to Sir Joseph
Hooker ("Life and Letters", III. page 319.): "I have been working like a
madman at Drosera. Here is a fact for you which is certain as you stand
where you are, though you won't believe it, that a bit of hair 1/78000 of
one grain in weight placed on gland, will cause ONE of the gland-bearing
hairs of Drosera to curve inwards." Here again Pfeffer (Pfeffer in
"Untersuchungen a. d. Bot. Inst. z. Tubingen", I. page 491.) has, as in so
many cases, added important facts to my father's observations. He showed
that if the leaf of Drosera is entirely freed from such vibrations as would
reach it if observed on an ordinary table, it does not react to small
weights, so that in fact it was the vibration of the minute fragment of
hair on the gland that produced movement. We may fancifully see an
adaptation to the capture of insects--to the dancing of a gnat's foot on
the sensitive surface.

Darwin was fond of telling how when he demonstrated the sensitiveness of
Drosera to Mr Huxley and (I think) to Sir John Burdon Sanderson, he could
perceive (in spite of their courtesy) that they thought the whole thing a
delusion. And the story ended with his triumph when Mr Huxley cried out,
"It IS moving."

Darwin's work on tendrils has led to some interesting investigations on the
mechanisms by which plants perceive stimuli. Thus Pfeffer (Tubingen
"Untersuchungen" I. page 524.) showed that certain epidermic cells
occurring in tendrils are probably organs of touch. In these cells the
protoplasm burrows as it were into cavities in the thickness of the
external cell-walls and thus comes close to the surface, being separated
from an object touching the tendril merely by a very thin layer of cell-
wall substance. Haberlandt ("Physiologische Pflanzenanatomie", Edition
III. Leipzig, 1904. "Sinnesorgane im Pflanzenreich", Leipzig, 1901, and
other publications.) has greatly extended our knowledge of vegetable
structure in relation to mechanical stimulation. He defines a sense-organ
as a contrivance by which the DEFORMATION or forcible change of form in the
protoplasm--on which mechanical stimulation depends--is rendered rapid and
considerable in amplitude ("Sinnesorgane", page 10). He has shown that in
certain papillose and bristle-like contrivances, plants possess such sense-
organs; and moreover that these contrivances show a remarkable similarity
to corresponding sense-organs in animals.

Haberlandt and Nemec ("Ber. d. Deutschen bot. Gesellschaft", XVIII. 1900.
See F. Darwin, Presidential Address to Section K, British Association,
1904.) published independently and simultaneously a theory of the mechanism
by which plants are orientated in relation to gravitation. And here again
we find an arrangement identical in principle with that by which certain
animals recognise the vertical, namely the pressure of free particles on
the irritable wall of a cavity. In the higher plants, Nemec and Haberlandt
believe that special loose and freely movable starch-grains play the part
of the otoliths or statoliths of the crustacea, while the protoplasm lining
the cells in which they are contained corresponds to the sensitive membrane
lining the otocyst of the animal. What is of special interest in our
present connection is that according to this ingenious theory (The original
conception was due to Noll ("Heterogene Induction", Leipzig, 1892), but his
view differed in essential points from those here given.) the sense of
verticality in a plant is a form of contact-irritability. The vertical
position is distinguished from the horizontal by the fact that, in the
latter case, the loose starch-grains rest on the lateral walls of the cells
instead of on the terminal walls as occurs in the normal upright position.
It should be added that the statolith theory is still sub judice;
personally I cannot doubt that it is in the main a satisfactory explanation
of the facts.

With regard to the RAPIDITY of the reaction of tendrils, Darwin records
("Climbing Plants", page 155. Others have observed movement after about
6".) that a Passion-Flower tendril moved distinctly within 25 seconds of
stimulation. It was this fact, more than any other, that made him doubt
the current explanation, viz. that the movement is due to unequal growth on
the two sides of the tendril. The interesting work of Fitting
(Pringsheim's "Jahrb." XXXVIII. 1903, page 545.) has shown, however, that
the primary cause is not (as Darwin supposed) contraction on the concave,
but an astonishingly rapid increase in growth-rate on the convex side.

On the last page of "Climbing Plants" Darwin wrote: "It has often been
vaguely asserted that plants are distinguished from animals by not having
the power of movement. It should rather be said that plants acquire and
display this power only when it is of some advantage to them."

He gradually came to realise the vividness and variety of vegetable life,
and that a plant like an animal has capacities of behaving in different
ways under different circumstances, in a manner that may be compared to the
instinctive movements of animals. This point of view is expressed in well-
known passages in the "Power of Movement". ("The Power of Movement in
Plants", 1880, pages 571-3.) "It is impossible not to be struck with the
resemblance between the...movements of plants and many of the actions
performed unconsciously by the lower animals." And again, "It is hardly an
exaggeration to say that the tip of the radicle...having the power of
directing the movements of the adjoining parts, acts like the brain of one
of the lower animals; the brain being seated within the anterior end of the
body, receiving impressions from the sense-organs, and directing the
several movements."

The conception of a region of perception distinct from a region of movement
is perhaps the most fruitful outcome of his work on the movements of
plants. But many years before its publication, viz. in 1861, he had made
out the wonderful fact that in the Orchid Catasetum ("Life and Letters",
III. page 268.) the projecting organs or antennae are sensitive to a touch,
and transmit an influence "for more than one inch INSTANTANEOUSLY," which
leads to the explosion or violent ejection of the pollinia. And as we have
already seen a similar transmission of a stimulus was discovered by him in
Sundew in 1860, so that in 1862 he could write to Hooker ("Life and
Letters", III. page 321.): "I cannot avoid the conclusion, that Drosera
possesses matter at least in some degree analogous in constitution and
function to nervous matter." I propose in what follows to give some
account of the observations on the transmission of stimuli given in the
"Power of Movement". It is impossible within the space at my command to
give anything like a complete account of the matter, and I must necessarily
omit all mention of much interesting work. One well-known experiment
consisted in putting opaque caps on the tips of seedling grasses (e.g. oat
and canary-grass) and then exposing them to light from one side. The
difference, in the amount of curvature towards the light, between the
blinded and unblinded specimens, was so great that it was concluded that
the light-sensitiveness resided exclusively in the tip. The experiment
undoubtedly proves that the sensitiveness is much greater in the tip than
elsewhere, and that there is a transmission of stimulus from the tip to the
region of curvature. But Rothert (Rothert, Cohn's "Beitrage", VII. 1894.)
has conclusively proved that the basal part where the curvature occurs is
also DIRECTLY sensitive to light. He has shown, however, that in other
grasses (Setaria, Panicum) the cotyledon is the only part which is
sensitive, while the hypocotyl, where the movement occurs, is not directly

It was however the question of the localisation of the gravitational sense
in the tip of the seedling root or radicle that aroused most attention, and
it was on this question that a controversy arose which has continued to the
present day.

The experiment on which Darwin's conclusion was based consisted simply in
cutting off the tip, and then comparing the behaviour of roots so treated
with that of normal specimens. An uninjured root when placed horizontally
regains the vertical by means of a sharp downward curve; not so a
decapitated root which continues to grow more or less horizontally. It was
argued that this depends on the loss of an organ specialised for the
perception of gravity, and residing in the tip of the root; and the
experiment (together with certain important variants) was claimed as
evidence of the existence of such an organ.

It was at once objected that the amputation of the tip might check
curvature by interfering with longitudinal growth, on the distribution of
which curvature depends. This objection was met by showing that an injury,
e.g. splitting the root longitudinally (See F. Darwin, "Linnean Soc.
Journal (Bot)." XIX. 1882, page 218.), which does not remove the tip, but
seriously checks growth, does not prevent geotropism. This was of some
interest in another and more general way, in showing that curvature and
longitudinal growth must be placed in different categories as regards the
conditions on which they depend.

Another objection of a much more serious kind was that the amputation of
the tip acts as a shock. It was shown by Rothert (See his excellent
summary of the subject in "Flora" 1894 (Erganzungsband), page 199.) that
the removal of a small part of the cotyledon of Setaria prevents the plant
curving towards the light, and here there is no question of removing the
sense-organ since the greater part of the sensitive cotyledon is intact.
In view of this result it was impossible to rely on the amputations
performed on roots as above described.

At this juncture a new and brilliant method originated in Pfeffer's
laboratory. (See Pfeffer, "Annals of Botany", VIII. 1894, page 317, and
Czapek, Pringsheim's "Jahrb." XXVII. 1895, page 243.) Pfeffer and Czapek
showed that it is possible to bend the root of a lupine so that, for
instance, the supposed sense-organ at the tip is vertical while the motile
region is horizontal. If the motile region is directly sensitive to
gravity the root ought to curve downwards, but this did not occur: on the
contrary it continued to grow horizontally. This is precisely what should
happen if Darwin's theory is the right one: for if the tip is kept
vertical, the sense-organ is in its normal position and receives no
stimulus from gravitation, and therefore can obviously transmit none to the
region of curvature. Unfortunately this method did not convince the
botanical world because some of those who repeated Czapek's experiment
failed to get his results.

Czapek ("Berichte d. Deutsch. bot. Ges." XV. 1897, page 516, and numerous
subsequent papers. English readers should consult Czapek in the "Annals of
Botany", XIX. 1905, page 75.) has devised another interesting method which
throws light on the problem. He shows that roots, which have been placed
in a horizontal position and have therefore been geotropically stimulated,
can be distinguished by a chemical test from vertical, i.e. unstimulated
roots. The chemical change in the root can be detected before any
curvature has occurred and must therefore be a symptom of stimulation, not
of movement. It is particularly interesting to find that the change in the
root, on which Czapek's test depends, takes place in the tip, i.e. in the
region which Darwin held to be the centre for gravitational sensitiveness.

In 1899 I devised a method (F. Darwin, "Annals of Botany", XIII. 1899, page
567.) by which I sought to prove that the cotyledon of Setaria is not only
the organ for light-perception, but also for gravitation. If a seedling is
supported horizontally by pushing the apical part (cotyledon) into a
horizontal tube, the cotyledon will, according to my supposition, be
stimulated gravitationally and a stimulus will be transmitted to the basal
part of the stem (hypocotyl) causing it to bend. But this curvature merely
raises the basal end of the seedling, the sensitive cotyledon remains
horizontal, imprisoned in its tube; it will therefore be continually
stimulated and will continue to transmit influences to the bending region,
which should therefore curl up into a helix or corkscrew-like form,--and
this is precisely what occurred.

I have referred to this work principally because the same method was
applied to roots by Massart (Massart, "Mem. Couronnes Acad. R. Belg." LXII.
1902.) and myself (F. Darwin, "Linnean Soc. Journ." XXXV. 1902, page 266.)
with a similar though less striking result. Although these researches
confirmed Darwin's work on roots, much stress cannot be laid on them as
there are several objections to them, and they are not easily repeated.

The method which--as far as we can judge at present--seems likely to solve
the problem of the root-tip is most ingenious and is due to Piccard.
(Pringsheim's "Jahrb." XL. 1904, page 94.)

Andrew Knight's celebrated experiment showed that roots react to
centrifugal force precisely as they do to gravity. So that if a bean root
is fixed to a wheel revolving rapidly on a horizontal axis, it tends to
curve away from the centre in the line of a radius of the wheel. In
ordinary demonstrations of Knight's experiment the seed is generally fixed
so that the root is at right angles to a radius, and as far as convenient
from the centre of rotation. Piccard's experiment is arranged differently.
(A seed is depicted below a horizontal dotted line AA, projecting a root
upwards.) The root is oblique to the axis of rotation, and the extreme tip
projects beyond that axis. Line AA represents the axis of rotation, T is
the tip of the root just above the line AA, and B is the region just below
line AA in which curvature takes place. If the motile region B is directly
sensitive to gravitation (and is the only part which is sensitive) the root
will curve (down and away from the vertical) away from the axis of
rotation, just as in Knight's experiment. But if the tip T is alone
sensitive to gravitation the result will be exactly reversed, the stimulus
originating in T and conveyed to B will produce curvature (up towards the
vertical). We may think of the line AA as a plane dividing two worlds. In
the lower one gravity is of the earthly type and is shown by bodies falling
and roots curving downwards: in the upper world bodies fall upwards and
roots curve in the same direction. The seedling is in the lower world, but
its tip containing the supposed sense-organ is in the strange world where
roots curve upwards. By observing whether the root bends up or down we can
decide whether the impulse to bend originates in the tip or in the motile

Piccard's results showed that both curvatures occurred and he concluded
that the sensitive region is not confined to the tip. (Czapek
(Pringsheim's "Jahrb." XXXV. 1900, page 362) had previously given reasons
for believing that, in the root, there is no sharp line of separation
between the regions of perception and movement.)

Haberlandt (Pringsheim's "Jahrb." XLV. 1908, page 575.) has recently
repeated the experiment with the advantage of better apparatus and more
experience in dealing with plants, and has found as Piccard did that both
the tip and the curving region are sensitive to gravity, but with the
important addition that the sensitiveness of the tip is much greater than
that of the motile region. The case is in fact similar to that of the oat
and canary-grass. In both instances my father and I were wrong in assuming
that the sensitiveness is confined to the tip, yet there is a concentration
of irritability in that region and transmission of stimulus is as true for
geotropism as it is for heliotropism. Thus after nearly thirty years the
controversy of the root-tip has apparently ended somewhat after the fashion
of the quarrels at the "Rainbow" in "Silas Marner"--"you're both right and
you're both wrong." But the "brain-function" of the root-tip at which
eminent people laughed in early days turns out to be an important part of
the truth. (By using Piccard's method I have succeeded in showing that the
gravitational sensitiveness of the cotyledon of Sorghum is certainly much
greater than the sensitiveness of the hypocotyl--if indeed any such
sensitiveness exists. See Wiesner's "Festschrift", Vienna, 1908.)

Another observation of Darwin's has given rise to much controversy.
("Power of Movement", page 133.) If a minute piece of card is fixed
obliquely to the tip of a root some influence is transmitted to the region
of curvature and the root bends away from the side to which the card was
attached. It was thought at the time that this proved the root-tip to be
sensitive to contact, but this is not necessarily the case. It seems
possible that the curvature is a reaction to the injury caused by the
alcoholic solution of shellac with which the cards were cemented to the
tip. This agrees with the fact given in the "Power of Movement" that
injuring the root-tip on one side, by cutting or burning it, induced a
similar curvature. On the other hand it was shown that curvature could be
produced in roots by cementing cards, not to the naked surface of the root-
tip, but to pieces of gold-beaters skin applied to the root; gold-beaters
skin being by itself almost without effect. But it must be allowed that,
as regards touch, it is not clear how the addition of shellac and card can
increase the degree of contact. There is however some evidence that very
close contact from a solid body, such as a curved fragment of glass,
produces curvature: and this may conceivably be the explanation of the
effect of gold-beaters skin covered with shellac. But on the whole it is
perhaps safer to classify the shellac experiments with the results of
undoubted injury rather than with those of contact.

Another subject on which a good deal of labour was expended is the sleep of
leaves, or as Darwin called it their NYCTITROPIC movement. He showed for
the first time how widely spread this phenomenon is, and attempted to give
an explanation of the use to the plant of the power of sleeping. His
theory was that by becoming more or less vertical at night the leaves
escape the chilling effect of radiation. Our method of testing this view
was to fix some of the leaves of a sleeping plant so that they remained
horizontal at night and therefore fully exposed to radiation, while their
fellows were partly protected by assuming the nocturnal position. The
experiments showed clearly that the horizontal leaves were more injured
than the sleeping, i.e. more or less vertical, ones. It may be objected
that the danger from cold is very slight in warm countries where sleeping
plants abound. But it is quite possible that a lowering of the temperature
which produces no visible injury may nevertheless be hurtful by checking
the nutritive processes (e.g. translocation of carbohydrates), which go on
at night. Stahl ("Bot. Zeitung", 1897, page 81.) however has ingeniously
suggested that the exposure of the leaves to radiation is not DIRECTLY
hurtful because it lowers the temperature of the leaf, but INDIRECTLY
because it leads to the deposition of dew on the leaf-surface. He gives
reasons for believing that dew-covered leaves are unable to transpire
efficiently, and that the absorption of mineral food-material is
correspondingly checked. Stahl's theory is in no way destructive of
Darwin's, and it is possible that nyctitropic leaves are adapted to avoid
the indirect as well as the direct results of cooling by radiation.

In what has been said I have attempted to give an idea of some of the
discoveries brought before the world in the "Power of Movement" (In 1881
Professor Wiesner published his "Das Bewegungsvermogen der Pflanzen", a
book devoted to the criticism of "The Power of Movement in Plants". A
letter to Wiesner, published in "Life and Letters", III. page 336, shows
Darwin's warm appreciation of his critic's work, and of the spirit in which
it is written.) and of the subsequent history of the problems. We must now
pass on to a consideration of the central thesis of the book,--the relation
of circumnutation to the adaptive curvatures of plants.

Darwin's view is plainly stated on pages 3-4 of the "Power of Movement".
Speaking of circumnutation he says, "In this universally present movement
we have the basis or groundwork for the acquirement, according to the
requirements of the plant, of the most diversified movements." He then
points out that curvatures such as those towards the light or towards the
centre of the earth can be shown to be exaggerations of circumnutation in
the given directions. He finally points out that the difficulty of
conceiving how the capacities of bending in definite directions were
acquired is diminished by his conception. "We know that there is always
movement in progress, and its amplitude, or direction, or both, have only
to be modified for the good of the plant in relation with internal or
external stimuli."

It may at once be allowed that the view here given has not been accepted by
physiologists. The bare fact that circumnutation is a general property of
plants (other than climbing species) is not generally rejected. But the
botanical world is no nearer to believing in the theory of reaction built
on it.

If we compare the movements of plants with those of the lower animals we
find a certain resemblance between the two. According to Jennings (H.S.
Jennings, "The Behavior of the Lower Animals". Columbia U. Press, N.Y.
1906.) a Paramoecium constantly tends to swerve towards the aboral side of
its body owing to certain peculiarities in the set and power of its cilia.
But the tendency to swim in a circle, thus produced, is neutralised by the
rotation of the creature about its longitudinal axis. Thus the direction
of the swerves IN RELATION TO THE PATH of the organism is always changing,
with the result that the creature moves in what approximates to a straight
line, being however actually a spiral about the general line of progress.
This method of motion is strikingly like the circumnutation of a plant, the
apex of which also describes a spiral about the general line of growth. A
rooted plant obviously cannot rotate on its axis, but the regular series of
curvatures of which its growth consists correspond to the aberrations of
Paramoecium distributed regularly about its course by means of rotation.
(In my address to the Biological Section of the British Association at
Cardiff (1891) I have attempted to show the connection between
circumnutation and RECTIPETALITY, i.e. the innate capacity of growing in a
straight line.) Just as a plant changes its direction of growth by an
exaggeration of one of the curvature-elements of which circumnutation
consists, so does a Paramoecium change its course by the accentuation of
one of the deviations of which its path is built. Jennings has shown that
the infusoria, etc., react to stimuli by what is known as the "method of
trial." If an organism swims into a region where the temperature is too
high or where an injurious substance is present, it changes its course. It
then moves forward again, and if it is fortunate enough to escape the
influence, it continues to swim in the given direction. If however its
change of direction leads it further into the heated or poisonous region it
repeats the movement until it emerges from its difficulties. Jennings
finds in the movements of the lower organisms an analogue with what is
known as pain in conscious organisms. There is certainly this much
resemblance that a number of quite different sub-injurious agencies produce
in the lower organisms a form of reaction by the help of which they, in a
partly fortuitous way, escape from the threatening element in their
environment. The higher animals are stimulated in a parallel manner to
vague and originally purposeless movements, one of which removes the
discomfort under which they suffer, and the organism finally learns to
perform the appropriate movement without going through the tentative series
of actions.

I am tempted to recognise in circumnutation a similar groundwork of
tentative movements out of which the adaptive ones were originally selected
by a process rudely representative of learning by experience.

It is, however, simpler to confine ourselves to the assumption that those
plants have survived which have acquired through unknown causes the power
of reacting in appropriate ways to the external stimuli of light, gravity,
etc. It is quite possible to conceive this occurring in plants which have
no power of circumnutating--and, as already pointed out, physiologists do
as a fact neglect circumnutation as a factor in the evolution of movements.
Whatever may be the fate of Darwin's theory of circumnutation there is no
doubt that the research he carried out in support of, and by the light of,
this hypothesis has had a powerful influence in guiding the modern theories
of the behaviour of plants. Pfeffer ("The Physiology of Plants", Eng. Tr.
III. page 11.), who more than any one man has impressed on the world a
rational view of the reactions of plants, has acknowledged in generous
words the great value of Darwin's work in the same direction. The older
view was that, for instance, curvature towards the light is the direct
mechanical result of the difference of illumination on the lighted and
shaded surfaces of the plant. This has been proved to be an incorrect
explanation of the fact, and Darwin by his work on the transmission of
stimuli has greatly contributed to the current belief that stimuli act
indirectly. Thus we now believe that in a root and a stem the mechanism
for the perception of gravitation is identical, but the resulting movements
are different because the motor-irritabilities are dissimilar in the two
cases. We must come back, in fact, to Darwin's comparison of plants to
animals. In both there is perceptive machinery by which they are made
delicately alive to their environment, in both the existing survivors are
those whose internal constitution has enabled them to respond in a
beneficial way to the disturbance originating in their sense-organs.


Professor of Botany in the University of Munich.

There is scarcely any subject to which Darwin devoted so much time and work
as to his researches into the biology of flowers, or, in other words, to
the consideration of the question to what extent the structural and
physiological characters of flowers are correlated with their function of
producing fruits and seeds. We know from his own words what fascination
these studies possessed for him. We repeatedly find, for example, in his
letters expressions such as this:--"Nothing in my life has ever interested
me more than the fertilisation of such plants as Primula and Lythrum, or
again Anacamptis or Listera." ("More Letters of Charles Darwin", Vol. II.
page 419.)

Expressions of this kind coming from a man whose theories exerted an epoch-
making influence, would be unintelligible if his researches into the
biology of flowers had been concerned only with records of isolated facts,
however interesting these might be. We may at once take it for granted
that the investigations were undertaken with the view of following up
important problems of general interest, problems which are briefly dealt
with in this essay.

Darwin published the results of his researches in several papers and in
three larger works, (i) "On the various contrivances by which British and
Foreign Orchids are fertilised by insects" (First edition, London, 1862;
second edition, 1877; popular edition, 1904.) (ii) "The effects of Cross
and Self fertilisation in the vegetable kingdom" (First edition, 1876;
second edition, 1878). (iii) "The different forms of Flowers on plants of
the same species" (First edition, 1877; second edition, 1880).

Although the influence of his work is considered later, we may here point
out that it was almost without a parallel; not only does it include a mass
of purely scientific observations, but it awakened interest in very wide
circles, as is shown by the fact that we find the results of Darwin's
investigations in floral biology universally quoted in school books; they
are even willingly accepted by those who, as regards other questions, are
opposed to Darwin's views.

The works which we have mentioned are, however, not only of special
interest because of the facts they contribute, but because of the MANNER in
which the facts are expressed. A superficial reader seeking merely for
catch-words will, for instance, probably find the book on cross and self-
fertilisation rather dry because of the numerous details which it contains:
it is, indeed, not easy to compress into a few words the general
conclusions of this volume. But on closer examination, we cannot be
sufficiently grateful to the author for the exactness and objectivity with
which he enables us to participate in the scheme of his researches. He
never tries to persuade us, but only to convince us that his conclusions
are based on facts; he always gives prominence to such facts as appear to
be in opposition to his opinions,--a feature of his work in accordance with
a maxim which he laid down:--"It is a golden rule, which I try to follow,
to put every fact which is opposed to one's preconceived opinion in the
strongest light." ("More Letters", Vol. II. page 324.)

The result of this method of presentation is that the works mentioned above
represent a collection of most valuable documents even for those who feel
impelled to draw from the data other conclusions than those of the author.
Each investigation is the outcome of a definite question, a "preconceived
opinion," which is either supported by the facts or must be abandoned.
"How odd it is that anyone should not see that all observation must be for
or against some view if it is to be of any service!" (Ibid. Vol. I. page

The points of view which Darwin had before him were principally the
following. In the first place the proof that a large number of the
peculiarities in the structure of flowers are not useless, but of the
greatest significance in pollination must be of considerable importance for
the interpretation of adaptations; "The use of each trifling detail of
structure is far from a barren search to those who believe in natural
selection." ("Fertilisation of Orchids" (1st edition), page 351; (2nd
edition 1904) page 286.) Further, if these structural relations are shown
to be useful, they may have been acquired because from the many variations
which have occurred along different lines, those have been preserved by
natural selection "which are beneficial to the organism under the complex
and ever-varying conditions of life." (Ibid. page 351.) But in the case
of flowers there is not only the question of adaptation to fertilisation to
be considered. Darwin, indeed, soon formed the opinion which he has
expressed in the following sentence,--"From my own observations on plants,
guided to a certain extent by the experience of the breeders of animals, I
became convinced many years ago that it is a general law of nature that
flowers are adapted to be crossed, at least occasionally, by pollen from a
distinct plant." ("Cross and Self fertilisation" (1st edition), page 6.)

The experience of animal breeders pointed to the conclusion that continual
in-breeding is injurious. If this is correct, it raises the question
whether the same conclusion holds for plants. As most flowers are
hermaphrodite, plants afford much more favourable material than animals for
an experimental solution of the question, what results follow from the
union of nearly related sexual cells as compared with those obtained by the
introduction of new blood. The answer to this question must, moreover,
possess the greatest significance for the correct understanding of sexual
reproduction in general.

We see, therefore, that the problems which Darwin had before him in his
researches into the biology of flowers were of the greatest importance, and
at the same time that the point of view from which he attacked the problems
was essentially a teleological one.

We may next inquire in what condition he found the biology of flowers at
the time of his first researches, which were undertaken about the year
1838. In his autobiography he writes,--"During the summer of 1839, and, I
believe, during the previous summer, I was led to attend to the cross-
fertilisation of flowers by the aid of insects, from having come to the
conclusion in my speculations on the origin of species, that crossing
played an important part in keeping specific forms constant." ("The Life
and Letters of Charles Darwin", Vol. I. page 90, London, 1888.) In 1841 he
became acquainted with Sprengel's work: his researches into the biology of
flowers were thus continued for about forty years.

It is obvious that there could only be a biology of flowers after it had
been demonstrated that the formation of seeds and fruit in the flower is
dependent on pollination and subsequent fertilisation. This proof was
supplied at the end of the seventeenth century by R.J. Camerarius (1665-
1721). He showed that normally seeds and fruits are developed only when
the pollen reaches the stigma. The manner in which this happens was first
thoroughly investigated by J.G. Kolreuter (1733-1806 (Kolreuter,
"Vorlaufige Nachricht von einigen das Geschlecht der Planzen betreffenden
Versuchen und Beobachtungen", Leipzig, 1761; with three supplements, 1763-
66. Also, "Mem. de l'acad. St Petersbourg", Vol. XV. 1809.)), the same
observer to whom we owe the earliest experiments in hybridisation of real
scientific interest. Kolreuter mentioned that pollen may be carried from
one flower to another partly by wind and partly by insects. But he held
the view, and that was, indeed, the natural assumption, that self-
fertilisation usually occurs in a flower, in other words that the pollen of
a flower reaches the stigma of the same flower. He demonstrated, however,
certain cases in which cross-pollination occurs, that is in which the
pollen of another flower of the same species is conveyed to the stigma. He
was familiar with the phenomenon, exhibited by numerous flowers, to which
Sprengel afterwards applied the term Dichogamy, expressing the fact that
the anthers and stigmas of a flower often ripen at different times, a
peculiarity which is now recognised as one of the commonest means of
ensuring cross-pollination.

With far greater thoroughness and with astonishing power of observation
C.K. Sprengel (1750-1816) investigated the conditions of pollination of
flowers. Darwin was introduced by that eminent botanist Robert Brown to
Sprengel's then but little appreciated work,--"Das entdeckte Geheimniss der
Natur im Bau und in der Befruchtung der Blumen" (Berlin, 1793); this is by
no means the least service to Botany rendered by Robert Brown.

Sprengel proceeded from a naive teleological point of view. He firmly
believed "that the wise Author of nature had not created a single hair
without a definite purpose." He succeeded in demonstrating a number of
beautiful adaptations in flowers for ensuring pollination; but his work
exercised but little influence on his contemporaries and indeed for a long
time after his death. It was through Darwin that Sprengel's work first
achieved a well deserved though belated fame. Even such botanists as
concerned themselves with researches into the biology of flowers appear to
have formerly attached much less value to Sprengel's work than it has
received since Darwin's time. In illustration of this we may quote C.F.
Gartner whose name is rightly held in the highest esteem as that of one of
the most eminent hybridologists. In his work "Versuche und Beobachtungen
uder die Befruchtungsorgane der vollkommeneren Gewachse und uber die
naturliche und kunstliche Befruchtung durch den eigenen Pollen" he also
deals with flower-pollination. He recognised the action of the wind, but
he believed, in spite of the fact that he both knew and quoted Kolreuter
and Sprengel, that while insects assist pollination, they do so only
occasionally, and he held that insects are responsible for the conveyance
of pollen; thorough investigations would show "that a very small proportion
of the plants included in this category require this assistance in their
native habitat." (Gartner, "Versucher und Beobachtungen...", page 335,
Stuttgart, 1844.) In the majority of plants self-pollination occurs.

Seeing that even investigators who had worked for several decades at
fertilisation-phenomena had not advanced the biology of flowers beyond the
initial stage, we cannot be surprised that other botanists followed to even
a less extent the lines laid down by Kolreuter and Sprengel. This was in
part the result of Sprengel's supernatural teleology and in part due to the
fact that his book appeared at a time when other lines of inquiry exerted a
dominating influence.

At the hands of Linnaeus systematic botany reached a vigorous development,
and at the beginning of the nineteenth century the anatomy and physiology
of plants grew from small beginnings to a flourishing branch of science.
Those who concerned themselves with flowers endeavoured to investigate
their development and structure or the most minute phenomena connected with
fertilisation and the formation of the embryo. No room was left for the
extension of the biology of flowers on the lines marked out by Kolreuter
and Sprengel. Darwin was the first to give new life and a deeper
significance to this subject, chiefly because he took as his starting-point
the above-mentioned problems, the importance of which is at once admitted
by all naturalists.

The further development of floral biology by Darwin is in the first place
closely connected with the book on the fertilisation of Orchids. It is
noteworthy that the title includes the sentence,--"and on the good effects
of intercrossing."

The purpose of the book is clearly stated in the introduction:--"The object
of the following work is to show that the contrivances by which Orchids are
fertilised, are as varied and almost as perfect as any of the most
beautiful adaptations in the animal kingdom; and, secondly, to show that
these contrivances have for their main object the fertilisation of each
flower by the pollen of another flower." ("Fertilisation of Orchids", page
1.) Orchids constituted a particularly suitable family for such
researches. Their flowers exhibit a striking wealth of forms; the
question, therefore, whether the great variety in floral structure bears
any relation to fertilisation (In the older botanical literature the word
fertilisation is usually employed in cases where POLLINATION is really in
question: as Darwin used it in this sense it is so used here.) must in
this case possess special interest.

Darwin succeeded in showing that in most of the orchids examined self-
fertilisation is either an impossibility, or, under natural conditions,
occurs only exceptionally. On the other hand these plants present a series
of extraordinarily beautiful and remarkable adaptations which ensure the
transference of pollen by insects from one flower to another. It is
impossible to describe adequately in a few words the wealth of facts
contained in the Orchid book. A few examples may, however, be quoted in
illustration of the delicacy of the observations and of the perspicuity
employed in interpreting the facts.

The majority of orchids differ from other seed plants (with the exception
of the Asclepiads) in having no dust-like pollen. The pollen, or more
correctly, the pollen-tetrads, remain fastened together as club-shaped
pollinia usually borne on a slender pedicel. At the base of the pedicel is
a small viscid disc by which the pollinium is attached to the head or
proboscis of one of the insects which visit the flower. Darwin
demonstrated that in Orchis and other flowers the pedicel of the pollinium,
after its removal from the anther, undergoes a curving movement. If the
pollinium was originally vertical, after a time it assumed a horizontal
position. In the latter position, if the insect visited another flower,
the pollinium would exactly hit the sticky stigmatic surface and thus
effect fertilisation. The relation between the behaviour of the viscid
disc and the secretion of nectar by the flower is especially remarkable.
The flowers possess a spur which in some species (e.g. Gymnadenia conopsea,
Platanthera bifolia, etc.) contains honey (nectar), which serves as an
attractive bait for insects, but in others (e.g. our native species of
Orchis) the spur is empty. Darwin held the opinion, confirmed by later
investigations, that in the case of flowers without honey the insects must
penetrate the wall of the nectarless spurs in order to obtain a nectar-like
substance. The glands behave differently in the nectar-bearing and in the
nectarless flowers. In the former they are so sticky that they at once
adhere to the body of the insect; in the nectarless flowers firm adherence
only occurs after the viscid disc has hardened. It is, therefore,
adaptively of value that the insects should be detained longer in the
nectarless flowers (by having to bore into the spur),--than in flowers in
which the nectar is freely exposed. "If this relation, on the one hand,
between the viscid matter requiring some little time to set hard, and the
nectar being so lodged that moths are delayed in getting it; and, on the
other hand, between the viscid matter being at first as viscid as ever it
will become, and the nectar lying all ready for rapid suction, be
accidental, it is a fortunate accident for the plant. If not accidental,
and I cannot believe it to be accidental, what a singular case of
adaptation!" ("Fertilisation of Orchids" (1st edition), page 53.)

Among exotic orchids Catasetum is particularly remarkable. One and the
same species bears different forms of flowers. The species known as
Catasetum tridentatum has pollinia with very large viscid discs; on
touching one of the two filaments (antennae) which occur on the gynostemium
of the flower the pollinia are shot out to a fairly long distance (as far
as 1 metre) and in such manner that they alight on the back of the insect,
where they are held. The antennae have, moreover, acquired an importance,
from the point of view of the physiology of stimulation, as stimulus-
perceiving organs. Darwin had shown that it is only a touch on the
antennae that causes the explosion, while contact, blows, wounding, etc. on
other places produce no effect. This form of flower proved to be the male.
The second form, formerly regarded as a distinct species and named
Monachanthus viridis, is shown to be the female flower. The anthers have
only rudimentary pollinia and do not open; there are no antennae, but on
the other hand numerous seeds are produced. Another type of flower, known
as Myanthus barbatus, was regarded by Darwin as a third form: this was
afterwards recognised by Rolfe (Rolfe, R.A. "On the sexual forms of
Catasetum with special reference to the researches of Darwin and others,"
"Journ. Linn. Soc." Vol. XXVII. (Botany), 1891, pages 206-225.) as the male
flower of another species, Catasetum barbatum Link, an identification in
accordance with the discovery made by Cruger in Trinidad that it always
remains sterile.

Darwin had noticed that the flowers of Catasetum do not secrete nectar, and
he conjectured that in place of it the insects gnaw a tissue in the cavity
of the labellum which has a "slightly sweet, pleasant and nutritious
taste." This conjecture as well as other conclusions drawn by Darwin from
Catasetum have been confirmed by Cruger--assuredly the best proof of the
acumen with which the wonderful floral structure of this "most remarkable
of the Orchids" was interpretated far from its native habitat.

As is shown by what we have said about Catasetum, other problems in
addition to those concerned with fertilisation are dealt with in the Orchid
book. This is especially the case in regard to flower morphology. The
scope of flower morphology cannot be more clearly and better expressed than
by these words: "He will see how curiously a flower may be moulded out of
many separate organs--how perfect the cohesion of primordially distinct
parts may become,--how organs may be used for purposes widely different
from their proper function,--how other organs may be entirely suppressed,
or leave mere useless emblems of their former existence." ("Fertilisation
of Orchids", page 289.)

In attempting, from this point of view, to refer the floral structure of
orchids to their original form, Darwin employed a much more thorough method
than that of Robert Brown and others. The result of this was the
production of a considerable literature, especially in France, along the
lines suggested by Darwin's work. This is the so-called anatomical method,
which seeks to draw conclusions as to the morphology of the flower from the
course of the vascular bundles in the several parts. (He wrote in one of
his letters, "...the destiny of the whole human race is as nothing to the
course of vessels of orchids" ("More Letters", Vol. II. page 275.)
Although the interpretation of the orchid flower given by Darwin has not
proved satisfactory in one particular point--the composition of the
labellum--the general results have received universal assent, namely "that
all Orchids owe what they have in common to descent from some
monocotyledonous plant, which, like so many other plants of the same
division, possessed fifteen organs arranged alternately three within three
in five whorls." ("Fertilisation of Orchids" (1st edition), page 307.)
The alterations which their original form has undergone have persisted so
far as they were found to be of use.

We see also that the remarkable adaptations of which we have given some
examples are directed towards cross-fertilisation. In only a few of the
orchids investigated by Darwin--other similar cases have since been
described--was self-fertilisation found to occur regularly or usually. The
former is the case in the Bee Ophrys (Ophrys apifera), the mechanism of
which greatly surprised Darwin. He once remarked to a friend that one of
the things that made him wish to live a few thousand years was his desire
to see the extinction of the Bee Ophrys, an end to which he believed its
self-fertilising habit was leading. ("Life and Letters", Vol. III. page
276 (footnote).) But, he wrote, "the safest conclusion, as it seems to me,
is, that under certain unknown circumstances, and perhaps at very long
intervals of time, one individual of the Bee Ophrys is crossed by another."
("Fertilisation of Orchids" page 71.)

If, on the one hand, we remember how much more sure self-fertilisation
would be than cross-fertilisation, and, on the other hand, if we call to
mind the numerous contrivances for cross-fertilisation, the conclusion is
naturally reached that "it is an astonishing fact that self-fertilisation
should not have been an habitual occurrence. It apparently demonstrates to
us that there must be something injurious in the process. Nature thus


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