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THE CENTURY SCIENCE SERIES

Edited by Sir Henry E. Roscoe, D.C.L., LL.D., F.R.S.



CHARLES DARWIN
AND THE THEORY OF NATURAL SELECTION


      *      *      *      *      *      *

The Century Science Series.

EDITED BY

SIR HENRY E. ROSCOE, D.C.L., F.R.S.


John Dalton and the Rise of Modern Chemistry.

  By Sir HENRY E. ROSCOE, F.R.S., &c.


Major Rennell, F.R.S., and the Rise of Modern English Geography.

  By Sir CLEMENTS R. MARKHAM, C.B., F.R.S., President of the Royal
  Geographical Society.


Justus von Liebig: his Life and Work (1803–1873).

  By W. A. SHENSTONE, F.I.C., Lecturer on Chemistry in Clifton College.


The Herschels and Modern Astronomy.

  By AGNES M. CLERKE, Author of “A Popular History of Astronomy during
  the 19th Century,” &c.


Charles Lyell and Modern Geology.

  By Professor T. G. BONNEY, F.R.S., &c.


James Clerk Maxwell and Modern Physics.

  By R. T. GLAZEBROOK, F.R.S., Fellow of Trinity College, Cambridge.


Humphry Davy, Poet and Philosopher.

  By T. E. THORPE, LL.D., F.R.S.


Charles Darwin and the Theory of Natural Selection.

  By EDWARD B. POULTON, M.A., F.R.S., Hope Professor of Zoology at the
  University of Oxford, &c.


_In Preparation._

Michael Faraday: his Life and Work.

  By Professor SILVANUS P. THOMPSON, F.R.S.


Pasteur: his Life and Work.

  By M. ARMAND RUFFER, M.D., Director of the British Institute of
  Preventive Medicine.


Hermann von Helmholtz.

  By A. W. RÜCKER, F.R.S., Professor of Physics in the Royal College of
  Science, London.


CASSELL & COMPANY, LIMITED, _London; Paris & Melbourne_.

      *      *      *      *      *      *


[Illustration:

  _Photo by Mr. James C. Christie, F.G.S., Glasgow._

STATUE OF CHARLES DARWIN.

(_By Boehm._)

CENTRAL HALL OF THE BRITISH MUSEUM OF NATURAL HISTORY.]


The Century Science Series

CHARLES DARWIN
AND THE THEORY OF NATURAL SELECTION

by

EDWARD B. POULTON
M.A., F.R.S., F.G.S., F.L.S., ETC.

Hope Professor of Zoology at the University of Oxford
Corresp. Memb. of the New York Academy of Sciences
Corresp. Memb. of the Boston Society of Nat. Hist.






Cassell and Company, Limited
London, Paris & Melbourne
1896
All Rights Reserved


[Illustration]




INTRODUCTION


In the following pages I have tried to express a sense of the greatness
of my subject by simplicity and directness of statement. The limits
of the work necessarily prevented any detailed treatment, the subject
of the work prevented originality. We have had the great “Life and
Letters” with us for nine years, and this I have used as a mine,
extracting what I believed to be the statements of chief importance for
the work in hand, and grouping them so as to present what I hope is
a connected account of Darwin’s life, when considered in relation to
his marvellous work; and especially to the great central discovery of
Natural Selection and its exposition in the “Origin of Species.”

In addition to the invaluable volumes which we owe to the industry,
taste, and skill of Francis Darwin, an immense number of other works
have been consulted. We live in an age of writing, and of speeches and
addresses; and the many sides of Darwin’s life and work have again and
again inspired the ablest men of our time to write and speak their
best--a justification for the freedom with which quotations are spread
over the following pages.

It is my pleasant duty to express my hearty thanks to many kind friends
who have helped in the production of this little work. Mr. Francis
Darwin has kindly permitted the use of many of Darwin’s letters,
which have not as yet been published, and he has given me valuable
information and criticism on many points. I have also gained much
by discussion and correspondence with my friends Dr. A. R. Wallace,
Professor E. Ray Lankester, and Professor Meldola. The latter has
freely given me the use of his valuable series of letters; and I owe
to my friend, Mr. Rowland H. Wedgwood, the opportunity of publishing a
single letter of very great interest.

The greater part of the volume formed the subject of two short courses
of lectures delivered in the Hope Department of the Oxford University
Museum in Michaelmas Term 1894 and Lent Term 1895.

                                                  EDWARD B. POULTON.

Oxford, _October, 1896_.




CONTENTS


  CHAPTER PAGE

  I.--THE SECRET OF DARWIN’S GREATNESS                                 9

  II.--BOYHOOD--EDINBURGH--CAMBRIDGE (1817–31)                        16

  III.--VOYAGE OF THE “BEAGLE” (1831–36)                              21

  IV.--CAMBRIDGE--LONDON--WORK UPON THE
            COLLECTIONS--MARRIAGE--GEOLOGICAL WORK--JOURNAL OF
            THE VOYAGE--CORAL REEFS--FIRST RECORDED THOUGHTS ON
            EVOLUTION (1837–42)                                       25

  V.--DOWN--GEOLOGY OF THE VOYAGE--WORK ON CIRRIPEDES (1842–54)       35

  VI.--THE GROWTH OF THE “ORIGIN OF SPECIES” (1837–58)                42

  VII.--GROWTH OF THE “ORIGIN” (_continued_)--CORRESPONDENCE WITH
            FRIENDS                                                   50

  VIII.--DARWIN AND WALLACE (1858)                                    60

  IX.--DARWIN’S SECTION OF THE JOINT MEMOIR READ BEFORE THE
            LINNEAN SOCIETY JULY 1, 1858                              65

  X.--WALLACE’S SECTION OF THE JOINT MEMOIR READ BEFORE THE
            LINNEAN SOCIETY JULY 1, 1858                              71

  XI.--COMPARISON OF DARWIN’S AND WALLACE’S SECTIONS OF THE JOINT
            MEMOIR--RECEPTION OF THEIR VIEWS--THEIR FRIENDSHIP        78

  XII.--THE GROWTH OF WALLACE’S CONVICTIONS ON EVOLUTION AND
            DISCOVERY OF NATURAL SELECTION--BORNEO 1855--TERNATE
            1858                                                      87

  XIII.--CANON TRISTRAM THE FIRST PUBLICLY TO ACCEPT THE THEORY
            OF NATURAL SELECTION (1859)                               92

  XIV.--THE PREPARATION OF THE “ORIGIN OF SPECIES” (1858–59)          95

  XV.--THE ORIGIN OF SPECIES (1859)                                  100

  XVI.--THE INFLUENCE OF DARWIN UPON LYELL (1859–64)                 105

  XVII.--INFLUENCE OF DARWIN UPON HOOKER AND ASA GRAY--NATURAL
            SELECTION AND DESIGN IN NATURE (1860–68)                 111

  XVIII.--INFLUENCE OF DARWIN UPON HUXLEY                            119

  XIX.--THE DIFFICULTY WITH WHICH THE “ORIGIN” WAS UNDERSTOOD        144

  XX.--THE DIFFICULTY WITH WHICH THE “ORIGIN” WAS UNDERSTOOD
            (_continued_)--VIEWS ON SPONTANEOUS GENERATION           153

  XXI.--VARIATION OF ANIMALS AND PLANTS UNDER DOMESTICATION:
            PANGENESIS (1868)                                        161

  XXII.--PANGENESIS AND CONTINUITY OF THE GERM-PLASM: DARWIN’S
            CONFIDENCE IN PANGENESIS                                 178

  XXIII.--DESCENT OF MAN--EXPRESSION OF EMOTIONS--EARTH-WORMS
            (1871–81)                                                186

  XXIV.--BOTANICAL WORKS (1862–86)                                   193

  XXV.--LETTERS FROM DARWIN TO PROFESSOR MELDOLA (1871–82)           199

  XXVI.--HIS LAST ILLNESS (1882)                                     219

  INDEX                                                              221




                            CHARLES DARWIN
                                  AND
                   THE THEORY OF NATURAL SELECTION.




CHAPTER I.

THE SECRET OF DARWIN’S GREATNESS.


Charles Robert Darwin was born at Shrewsbury on February 12th, 1809,
the year which witnessed the birth of Alfred Tennyson, W. E. Gladstone,
and Abraham Lincoln.

Oliver Wendell Holmes, born in the same year, delighted to speak of the
good company in which he came into the world. On January 27th, 1894,
I had the great pleasure of sitting next to him at a dinner of the
Saturday Club in Boston, and he then spoke of the subject with the same
enthusiasm with which he deals with it in his writings; mentioning the
four distinguished names, and giving a brief epigrammatic description
of each with characteristic felicity. Dr. Holmes further said that he
remembered with much satisfaction an occasion on which he was able to
correct Darwin on a matter of scientific fact. He could not remember
the details, but we may hope for their ultimate recovery, for he said
that Darwin had written a courteous reply accepting the correction.

[Sidenote: HIS FAMILY.]

Charles Darwin’s grandfather, Erasmus Darwin (1731–1802), was a man of
great genius. He speculated upon the origin of species, and arrived at
views which were afterwards independently enunciated by Lamarck. He
resembled this great zoologist in fertility of imagination, and also in
the boldness with which he put forward suggestions, many of which were
crude and entirely untested by an appeal to facts. The poetical form in
which a part of his work was written was, doubtless, largely due to the
traditions and customs of the age in which he lived.

Robert Waring (1766–1848), the father of Charles Darwin, was the second
son of Erasmus. He married a daughter of the great Josiah Wedgwood.
Although his mother died when he was only eight years old, and Darwin
remembered very little of her, there is evidence that she directed his
attention to Nature (“Autobiography,” p. 28, footnote). Dr. Darwin
followed his father’s profession, commencing a very successful medical
practice at Shrewsbury before he was twenty-one. He was a man of great
penetration, especially in the discernment of character--a power which
was of the utmost value to him in his profession. Dr. Darwin had two
sons and four daughters: Charles was the younger son and fourth child,
his brother Erasmus being the third.

Even in this mere outline there is evidence of hereditary genius
in the Darwin family--evidence which becomes irresistible when all
available details of every member of the family are brought together,
as they are in the great “Life and Letters.” When it is further
remembered that two of Charles Darwin’s sons have achieved distinction
as scientific investigators, it will be admitted that the history of
the family affords a most striking example of hereditary intellectual
power.

There is nothing in this history to warrant the belief that the nature
and direction of hereditary genius receive any bias from the line of
intellectual effort pursued by a parent. We recognise the strongest
evidence for hereditary capacity, but none at all for the transmission
of results which follow the employment of capacity. Thus Erasmus
inherited high intellectual power, with a bias entirely different from
that of his younger brother Charles--his interests being literary
and artistic rather than scientific. The wide difference between the
brothers seems to have made a great impression upon Charles, for he
wrote:--

      “Our minds and tastes were, however, so different, that I do not
      think I owe much to him intellectually. I am inclined to agree
      with Francis Galton in believing that education and environment
      produce only a small effect on the mind of anyone, and that most
      of our qualities are innate” (“Life and Letters,” 1887, p. 22).

Equally significant is the fact that Professor George Darwin’s
important researches in mathematics have been applied to
astronomy--subjects which were not pursued by his father.

[Sidenote: CHARACTER AND POWERS.]

It appears probable that Charles Darwin’s unique power was largely
due to the inheritance of the imagination of his grandfather combined
with the acute observation of his father. Although he possessed an
even larger share of both these qualities than his predecessors, it
is probable that he owed more to their co-operation than to the high
degree of their development.

It is a common error to suppose that the intellectual powers which
make the poet or the historian are essentially different from those
which make the man of science. Powers of observation, however acute,
could never make a scientific discoverer; for discovery requires the
creative effort of the imagination. The scientific man does not stumble
upon new facts or conclusions by accident; he finds what he looks for.
The problem before him is essentially similar to that of the historian
who tries to create an accurate and complete picture of an epoch out
of scattered records of contemporary impressions more or less true,
and none wholly true. Fertility of imagination is absolutely essential
for that step from the less to the more perfectly known which we call
discovery.

But fertility of imagination alone is insufficient for the highest
achievement in poetry, history, or science; for in all these subjects
the strictest self-criticism and the soundest judgment are necessary
in order to ensure that the results are an advance in the direction
of the truth. A delicately-adjusted balance between the powers of
imagination and the powers which hold imagination in check, is
essential in the historian who is to provide us with a picture of a
past age, which explains the mistaken impression gained by a more or
less prejudiced observer who saw but a small part of it from a limited
standpoint, and has handed down his impression to us. A poem which
sheds new light upon the relation between mind and mind, requires to
be tested and controlled by constant and correct observation, like a
hypothesis in the domain of the natural sciences.

It is probable, then, that the secret of Darwin’s strength lay in the
perfect balance between his powers of imagination and those of accurate
observation, the creative efforts of the one being ever subjected to
the most relentless criticism by the employment of the other. We shall
never know, I have heard Professor Michael Foster say, the countless
hypotheses which passed through the mind of Darwin, and which, however
wild and improbable, were tested by an appeal to Nature, and were then
dismissed for ever.

Darwin’s estimate of his own powers is given with characteristic
candour and modesty in the concluding paragraph of his “Autobiography”
(“Life and Letters,” 1887, p. 107):--

      “Therefore my success as a man of science, whatever this
      may have amounted to, has been determined, as far as I can
      judge, by complex and diversified mental qualities and
      conditions. Of these, the most important have been--the love
      of science--unbounded patience in long reflecting over any
      subject--industry in observing and collecting facts--and a fair
      share of invention as well as of common sense. With such moderate
      abilities as I possess, it is truly surprising that I should have
      influenced to a considerable extent the belief of scientific men
      on some important points.”

We also know from other sources that Darwin looked upon the creative
powers as essential to scientific progress. Thus he wrote to Wallace
in 1857: “I am a firm believer that without speculation there is no
good and original observation.” He also says in the “Autobiography”:
“I have steadily endeavoured to keep my mind free so as to give up any
hypothesis, however much beloved (and I cannot resist forming one on
every subject), as soon as facts are shown to be opposed to it.”

[Sidenote: VALUE OF HYPOTHESIS.]

I have thought it worth while to insist thus strongly on the high value
attached by Darwin to hypothesis, controlled by observation, in view
of certain recent attacks upon this necessary weapon for scientific
advance. Thus Bateson, in his “Materials for the Study of Variation”
(London, 1894), p. 7, says: “In the old time the facts of Nature
were beautiful in themselves and needed not the rouge of speculation
to quicken their charm, but that was long ago before Modern Science
was born.” The author does not specify the period in the history of
science when discovery proceeded without hypothesis. A study of the
earlier volumes of the _Philosophical Transactions_ reveals a far
greater interest in speculation than in the facts of Nature. We can
hardly call those ages anything but speculative which received with
approval the suggestions that geese were developed from barnacles which
grew upon trees; that swallows hibernated at the bottom of lakes;
that the Trade-winds were due to the breath of a sea-weed. Bateson’s
statement requires to be reversed in order to become correct. Modern
science differs from the science of long ago in its greater attention
to the facts of Nature and its more rigid control over the tendency
to hypothesis; although hypothesis remains, and must ever remain, as
the guide and inspirer of observation and the discovery of fact.[A]
Although Darwin has kindled the imagination of hundreds of workers, and
has thus been the cause of an immense amount of speculation, science
owes him an even larger debt for the innumerable facts discovered under
the guidance of this faculty.




CHAPTER II.

BOYHOOD--EDINBURGH--CAMBRIDGE (1817–31).


Of Darwin’s boyhood and school-life we only know the facts given in his
brief “Autobiography,” written when he was sixty-seven, together with
those collected by his son Francis and appended in the form of notes.
He first went to Mr. Case’s day-school in Shrewsbury in 1817, the year
of his mother’s death. At this time, although only eight years old, his
interest in natural history and in collecting was well established.
“The passion for collecting, which leads a man to be a systematic
naturalist, a virtuoso, or a miser, was very strong in me, and was
clearly innate, as none of my sisters or brother had this taste.”

In the following year he went to Dr. Butler’s school in Shrewsbury,
where he remained seven years. He does not appear to have profited
much by the classical instruction which at that time received
almost exclusive attention. His interest seems to have been chiefly
concentrated upon sport; but whenever a subject attracted him he
worked hard at it, and it is probable that he would have conveyed a
very different impression of his powers to the masters and his father
if scientific subjects had been taught, as they are now to a moderate
extent in many schools.

That he was a keen observer for his age is clear from the fact that,
when he was only ten, he was much interested and surprised to notice
that the insects he found on the Welsh coast were different from those
in Shropshire. His most valuable education was received out of school
hours--collecting, and working at chemistry with his brother Erasmus,
although this latter study drew down upon him the rebukes of Dr. Butler
for wasting time on such useless subjects.

[Sidenote: AT EDINBURGH.]

He was removed from school early, and in 1825 went to Edinburgh to
study medicine--a subject for which he seemed to be unfitted by nature.
The methods of instruction by lectures did not benefit him; he was
disgusted at dissection, and could not endure to witness an operation.
And yet here it was evident, as it became afterwards at Cambridge,
that Darwin--although seeming to be by no means above the average when
judged by ordinary standards--possessed in reality a very remarkable
and attractive personality. There can be no other explanation of the
impression he made upon distinguished men who were much older than
himself, and the friendships he formed with those of his own age who
were afterwards to become eminent.

Thus at Edinburgh he was well acquainted with Dr. Grant and Mr.
Macgillivray, the curator of the museum, and worked at marine zoology
in company with the former. Here, too, in 1826, he made his first
scientific discovery, and read a paper before the Plinian Society,
proving that so-called eggs of Flustra were in reality free-swimming
larvæ. And it is evident from his “Autobiography” that he took every
opportunity of hearing and learning about scientific subjects.

Darwin’s love of sport remained as keen as ever at this period and at
Cambridge, and he speaks with especial enthusiasm of his visits in the
autumn to Maer, the home of his uncle, Josiah Wedgwood, who afterwards
exerted so important an influence upon his life.

[Sidenote: AT CAMBRIDGE.]

After Darwin had been at Edinburgh for two sessions, his father
realised that he did not like the thought of the medical profession,
and suggested that he should become a clergyman. With this intention
he was sent to Cambridge in the beginning of 1828, after spending some
months in recovering the classics he had learnt at school.

He joined Christ’s College, and passed his final examination in
January, 1831, being tenth in the list of those who do not seek
honours. The immense, and in many respects disastrous, development
of the competitive examination system since that time has almost
banished from our universities the type of student represented by
Darwin--the man who takes the easiest road to a degree and obtains it
with the minimum of effort, but who all the time is being benefited by
residence, studying, without any thought of examinations, the subjects
which are of special interest to him, and seeking personal contact
with older men who have reached the highest eminence in those subjects.

He seems to have led a somewhat double life at Cambridge, his
intense love of sport taking him into a pleasure-loving set, while
his intellectual interests made him the intimate friend of Whitley,
who became Senior Wrangler, and of Professor Henslow, to whom he
was introduced by his second cousin, W. Darwin Fox, who also first
interested him in entomology. He became so keen a collector of beetles
that his successes and experiences in this direction seem to have
impressed him more deeply than anything else at Cambridge. Entomology,
and especially beetles, form the chief subject of those of his
Cambridge letters which have been recovered.

Darwin’s friendship with Henslow, which was to have a most important
effect on his life, very soon deepened. They often went long walks
together, so that he was called “the man who walks with Henslow.” This
fact and the subsequent rapidly formed intimacy with Professor Adam
Sedgwick, indicate that he was remarkable among the young men of his
standing.

One of his undergraduate friends, J. M. Herbert, afterwards County
Court Judge for South Wales, retained the most vivid recollection of
Darwin at Cambridge, and contributed the following impression of his
character to the “Life and Letters”:--

      “It would be idle for me to speak of his vast intellectual powers
      ... but I cannot end this cursory and rambling sketch without
      testifying, and I doubt not all his surviving college friends
      would concur with me, that he was the most genial, warm-hearted,
      generous and affectionate of friends; that his sympathies were
      with all that was good and true; and that he had a cordial
      hatred for everything false, or vile, or cruel, or mean, or
      dishonourable. He was not only great, but pre-eminently good, and
      just, and loveable.”

Two books greatly influenced Darwin--Herschel’s “Introduction to the
Study of Natural Philosophy,” which, he said, “stirred up in me a
burning zeal to add even the most humble contribution to the noble
structure of Natural Science”; and Humboldt’s “Personal Narrative,”
which roused in him the longing to travel--a desire which was soon
afterwards gratified by his voyage in the _Beagle_.

“Upon the whole,” he says, “the three years which I spent at Cambridge
were the most joyful in my happy life; for I was then in excellent
health, and almost always in high spirits.”

After passing his last examination, Darwin had still two terms’
residence to keep, and was advised by Henslow to study geology. To
this end Henslow asked Sedgwick to allow Darwin to go with him on a
geological excursion in North Wales in August, 1831. He thus gained
experience which was of the utmost value during the voyage of the
_Beagle_.




CHAPTER III.

VOYAGE OF THE “BEAGLE” (1831–36).


About the time of the excursion with Sedgwick (the exact date is
uncertain) Professor Henslow received a letter from George Peacock
(formerly Dean of Ely and Lowndean Professor of Astronomy at Cambridge)
stating that he had the offer to recommend a young man as naturalist
to accompany Captain Fitzroy on a surveying expedition to many parts
of the world. Leonard Jenyns (afterwards Blomefield) was evidently
considered to be the most suitable person for the position, but he
was unable to accept it. Henslow at once wrote (August 24th, 1831) to
Darwin, and advised him to do his utmost to obtain the position, and
Darwin found the letter waiting for him on his return home after the
geological excursion with Sedgwick. As his father greatly disliked the
idea, Darwin at once wrote (August 30th) and declined, and the next
day went to Maer to be ready for the shooting on September 1st. Here,
however, his uncle, Josiah Wedgwood, took a very different view from
that adopted by his father, with the result that both he and Darwin
wrote (August 31st) to Shrewsbury and reopened the question. Darwin’s
letter shows the most touching deference to his father’s wishes, and
the gravest apprehension lest he should be rendered “uncomfortable” or
“uneasy” by any further suggestion as to the possibility of the voyage,
although his father had said, “If you can find any man of common-sense
who advises you to go, I will give my consent.” We also learn from the
“Autobiography” that his uncle sent for him whilst out shooting and
drove him the thirty miles to Shrewsbury, in order that they might talk
with his father, who then at once consented. This must have been on
September 1st, 1831.

From this time until he went to Plymouth, on October 24th--the final
start was not until December 27th--his letters show that he had a very
busy time making purchases and preparing for the voyage. These letters
breathe the warmest affection to the members of his family and his
friends, together with the keenest enthusiasm for Captain Fitzroy, the
ship, and the voyage.

The voyage of the _Beagle_ lasted from December 27th, 1831, to October
2nd, 1836. Darwin says that it was “by far the most important event in
my life, and has determined my whole career.... I have always felt that
I owe to the voyage the first real training or education of my mind”
(_l. c._, p. 61). He attributes the greatest share in this training to
geology, among the special sciences, because of the reasoning involved
in making out the structure of a new and unknown district; but he
considers that the habits of “energetic industry and of concentrated
attention” which he then acquired were of the utmost importance, and
the secret of all his success in science. He tells us that the love of
sport was present at first in all its keenness, but that he gradually
abandoned it for scientific work.

Among his numerous observations and discoveries during the voyage,
those which appear to stand out in his mind so that he quotes them
in his “Autobiography” are--the explanation of the forms of coral
islands, the geological structure of St. Helena and other islands, and
the relations between the animals and plants of the several Galapagos
islands to each other and to those of South America. His letters and
the collections which he sent home attracted much attention; and
Sedgwick told Dr. Darwin that his son would take a place among the
leading scientific men. When Darwin heard this from his sisters, he
says, “I clambered over the mountains of Ascension with a bounding
step, and made the volcanic rocks resound under my geological hammer.”
His letters during the voyage are full of enthusiasm and of longing to
return to his family and friends.

There was the same conflict between the naval and scientific
departments of the _Beagle_ on the untidiness of the decks which was
afterwards repeated on the _Challenger_, where I have been told that
one of the naval authorities used to say, with resigned disgust, “Oh,
no, we’re not a man-of-war, we’re only a ---- dredger!”

In the course of the voyage the following countries and islands were
visited in the order given:--The Cape de Verde Islands, St. Paul’s
Rocks, Fernando Noronha, South America (including the Galapagos
Archipelago, the Falkland Islands, and Tierra del Fuego), Tahiti, New
Zealand, Australia, Tasmania, Keeling Island, Maldive Coral Atolls,
Mauritius, St. Helena, Ascension. Brazil was then visited again for a
short time, the _Beagle_ touching at the Cape de Verde Islands and the
Azores on the voyage home.

Darwin says, concerning the intellectual effect of his work during the
voyage:--

      “That my mind became developed through my pursuits during the
      voyage is rendered probable by a remark made by my father, who
      was the most acute observer whom I ever saw, of a sceptical
      disposition, and far from being a believer in phrenology; for on
      first seeing me after the voyage he turned round to my sisters,
      and exclaimed, ‘Why the shape of his head is quite altered!’”
      (_l. c._, pp. 63, 64).




CHAPTER IV.

CAMBRIDGE--LONDON--WORK UPON THE COLLECTIONS--MARRIAGE--GEOLOGICAL
WORK--JOURNAL OF THE VOYAGE--CORAL REEFS--FIRST RECORDED THOUGHTS ON
EVOLUTION (1837–42).


Darwin reached England October 2nd, 1836, and was home at Shrewsbury
October 5th (according to his Letters; the 4th is the date given by
Francis Darwin in the “Life and Letters”). The two years and three
months which followed he describes as the most active ones he ever
spent. After visiting his family, he stayed three months in Cambridge,
working at his collection of rocks, writing his “Naturalist’s Voyage,”
and one or two scientific papers. He then (March 7th, 1837) took
lodgings in 36, Great Marlborough Street, London, where he remained
until his marriage, January 29th, 1839. The apathy of scientific
men--even those in charge of museums--caused him much depression,
and he found great difficulty in getting specialists to work out his
collections, although the botanists seem to have been keener than the
zoologists.

The commencement of his London residence is of the deepest interest,
as the time at which he began to reflect seriously on the origin of
species. Thus he says in the “Autobiography”:--“In July I opened my
first note-book for facts in relation to the Origin of Species, about
which I had long reflected, and never ceased working for the next
twenty years.” Furthermore, his pocket-book for 1837 contained the
words:--“In July opened first note-book on Transmutation of Species.
Had been greatly struck from about the month of previous March” (he was
then just over twenty-eight years old) “on character of South American
fossils, and species on Galapagos Archipelago. These facts (especially
latter) origin of all my views.” It is, perhaps, worth while to
explain in greater detail the nature of this evidence which appealed
so strongly to Darwin’s mind. The Edentata (sloths, ant-eaters,
armadilloes, etc.) have their metropolis in South America, and in the
later geological formations of this country the skeletons of gigantic
extinct animals of the same order (Megatherium, Mylodon, Glyptodon,
etc.) are found; and Darwin was doubtless all the more impressed by
discovering such remains for himself. In his “Autobiography” he says:
“During the voyage of the _Beagle_ I had been deeply impressed by
discovering in the Pampean formation great fossil animals covered with
armour like that on existing armadilloes;...”

Darwin was thus led to conclude that there was some genetic connection
between the animals which have succeeded each other in the same
district; for in a theory of destructive cataclysms, followed by
re-creations--or, indeed, in any theory of special creation--there
seemed no adequate reason why the successive forms should belong
to the same order. In his “Naturalist’s Voyage Round the World” he
says, speaking of this subject: “This wonderful relationship in the
same continent between the dead and the living will, I do not doubt,
hereafter throw more light on the appearance of organic beings on our
earth, and their disappearance from it, than any other class of facts”
(p. 173 in the third edition).

[Sidenote: THE GALAPAGOS.]

The other class of evidence which impressed him even more strongly
was afforded by the relations between the animals and plants of the
several islands of the Galapagos Archipelago and between those of
the Archipelago and of South America, nearly 600 miles to the East.
Although the inhabitants of the separate islands show an astonishing
amount of peculiarity, the species are nearly related, and also exhibit
American affinities. Concerning this, Darwin writes in his “Voyage”
(p. 398 in the third edition): “Reviewing the facts here given, one
is astonished at the amount of creative force--if such an expression
may be used--displayed on these small, barren, and rocky islands; and
still more so at its diverse and yet analogous action on points so near
each other.” Here, too, the facts were unintelligible on a theory of
separate creation of species, but were at once explained if we suppose
that the inhabitants were the modified descendants of species which
had migrated from South America--the migrations to the Archipelago and
between the separate islands being rendered extremely rare from the
depth of the sea, the direction of the currents, and the absence of
gales. In this way time for specific modification was provided before
the partially modified form could interbreed with the parent species
and thus lose its own newly-acquired characteristics.

Although Darwin made these observations on the _Beagle_, they
required, as Huxley has suggested (Obituary [1888], “Darwiniana”:
Collected Essays, vol. ii., pp. 274–275. London, 1893), careful and
systematic working out before they could be trusted as a basis on
which to speculate; and this could not be done until the return home.
The following letter written by Darwin to Dr. Otto Zacharias in 1877
confirms this opinion. It was sent to Huxley by Francis Darwin, and is
printed in “Darwiniana” (_l. c._, p. 275):--

      “When I was on board the ‘Beagle,’ I believed in the permanence
      of species, but, as far as I can remember, vague doubts
      occasionally flitted across my mind. On my return home in the
      autumn of 1836, I immediately began to prepare my journal for
      publication, and then saw how many facts indicated the common
      descent of species, so that in July, 1837, I opened a note-book
      to record any facts which might bear on the question. But I did
      not become convinced that species were mutable until I think two
      or three years had elapsed.”

It is interesting to note that both the lines of evidence which
appealed to Darwin so strongly, point to evolution, but not to any
causes of evolution. The majority of mankind were only convinced of
this process when some conception as to its causes had been offered to
them; Darwin took the more logical course of first requiring evidence
that the process takes place, and then inquiring for its causes.

[Sidenote: EARLY NOTES ON SPECIES.]

The first indication of these thoughts in any of his published letters
is in one to his cousin Fox written in June, 1838, in which, after
alluding to some questions he had previously asked about the crossing
of animals, he says, “It is my prime hobby, and I really think some day
I shall be able to do something in that most intricate subject--species
and varieties.”

He is rather more definite in a letter to Sir Charles Lyell, written
September 13th in the same year:--

      “I have lately been sadly tempted to be idle--that is, as far
      as pure geology is concerned--by the delightful number of new
      views which have been coming in thickly and steadily,--on the
      classification and affinities and instincts of animals--bearing
      on the question of species. Note-book after note-book has been
      filled with facts which begin to group themselves _clearly_ under
      sub-laws.”

On February 16th, 1838, he was appointed Secretary of the Geological
Society, a position which he retained until February 1st, 1841. During
these two years after the voyage he saw much of Sir Charles Lyell,
whose teachings had been of the greatest help to him during the
voyage, and whose method of appealing to natural causes rather than
supernatural cataclysms undoubtedly had a most important influence
on the development of Darwin’s mind. This influence he delighted to
acknowledge, dedicating to Lyell the second edition of his “Voyage,”
“as an acknowledgment that the chief part of whatever scientific merit
this ‘Journal’ and the other works of the author may possess has been
derived from studying the well-known and admirable ‘Principles of
Geology.’”

[Sidenote: EARLY WORKS.]

At this period he finished his “Journal,” which was published in
1839 as Vol. III. of the “Narrative of the Surveying Voyages of Her
Majesty’s Ships _Adventure_ and _Beagle_.” A second edition was
published in a separate form in 1845 as the “Journal of Researches into
the Natural History and Geology of the Countries visited during the
Voyage of H.M.S. _Beagle_ round the World, under the command of Captain
Fitz-Roy, R.N.”; and a third edition--but very slightly altered--in
1860, under the title “A Naturalist’s Voyage: Journal of Researches,
etc.” This book is generally admitted to deserve above all others the
generous description which Darwin gave to Sir Joseph Hooker of Belt’s
admirable “Naturalist in Nicaragua”--as “the best of all Natural
History journals which have ever been published.”

A comparison between the first and second editions indicates, but by
no means expresses, his growing convictions on evolution and natural
selection. Natural selection he had not discovered when the MS. of the
first edition was complete; and if we had no further evidence we could
not, from any passage in the work, maintain that he was convinced of
evolution. His great caution in dealing with so tremendous a problem
explains why the second edition does not reflect the state of his mind
at the time of its publication. He tells us (“Autobiography”) that in
the preparation of this second edition he “took much pains,” and we may
feel confident that much of this care was given to the decision as to
how much he should reveal and how much withhold of the thoughts which
were occupying his mind, and the conclusions to which he had at that
time arrived. That he did attribute much importance to the evolutionary
passages added in the second edition is shown by his letter to Lyell
(July, 1845), in which he alludes to some of them, and specially asks
Lyell to read the pages on the causes of extinction.

He also edited and superintended the “Zoology of the Voyage of H.M.S.
_Beagle_,” the special parts of which were written by various eminent
systematists, and appeared separately between 1839 and 1843.

He also read several papers before the Geological Society, including
two (1838 and 1840) on the Formation of Mould by the Action of
Earth-Worms--a subject to which he returned, and upon which his last
volume (published in 1881) was written. He also read a paper on the
Parallel Roads of Glen Roy before the Royal Society (published in
the _Phil. Trans._, 1839). These wonderful parallel terraces are now
admitted to be due to the changes of level in a lake following those of
an ice-barrier at the mouth of the valley. At the time Darwin studied
them, the terraces were believed to have been formed by a lake dammed
back by a barrier of rock and alluvium; this he proved to be wrong, and
as no other barrier was then available--for the evidences of glaciation
had not then been discovered by Agassiz--he was driven, on the method
of exclusion, to the action of the sea. Upon this subject he says, in
the “Autobiography,” “My error has been a good lesson to me never to
trust in science to the principle of exclusion.”

On January 29th, 1839, he married his cousin, Emma Wedgwood, the
daughter of Josiah Wedgwood, of Maer. They resided at 12, Upper Gower
Street until September 14th, 1842, when they settled at Down.

The few graceful and touching words in which Francis Darwin, in the
“Life and Letters,” alludes to his father’s married life show how deep
is the debt of gratitude which the world owes to Mrs. Darwin; for
without her constant and loving care it would have been impossible for
Darwin to have accomplished his life-work.

[Sidenote: ON CORAL REEFS.]

During these years in London his health broke down many times; so that
he says, in the “Autobiography”: “I did less scientific work, though I
worked as hard as I possibly could, than during any other equal length
of time in my life.” He chiefly worked at his book on “The Structure
and Distribution of Coral Reefs,” published in 1842 (second edition in
1874). This work contains an account of Darwin’s well-known theory upon
the origin of the various coral formations--fringing reefs, barrier
reefs, and atolls--by the upward growth of the reef keeping pace with
the gradual sinking of the island upon which it is based, so that the
living corals always remain at the surface under the most favourable
conditions, while beneath them is an ever-thickening reef formed of
dead coral, until at length, by continuing this process, the climax
is reached in the atoll, in which the original island has altogether
disappeared beneath the surface of a central lagoon enclosed in a
ring formed by the living edge of the reef. This theory, after being
accepted for many years, has recently been disputed, chiefly as the
result of the observations made on the _Challenger_ expedition. It
is contended by Dr. John Murray “that it is not necessary to call in
subsidence to explain any of the characteristic features of barrier
reefs or atolls, and that all these features would exist alike in areas
of slow elevation, of rest, or of slow subsidence” (_Nature_, August
12th, 1880, p. 337). It cannot be said that this controversy is yet
settled, or that the supporters of either theory have proved that the
other does not hold--at any rate, in certain cases.

Among his geological papers written at this time was one describing the
glacial phenomena observed during a tour in North Wales. This paper
(_Philosophical Magazine_, 1842, p. 352) is placed by Sir Archibald
Geikie “almost at the top of the long list of English contributions to
the history of the Ice Age.”

At this time, too, he was reflecting and collecting evidence for
the great work of his life. Thus in January, 1841, he writes to his
cousin, Darwin Fox, asking for “all kinds of facts about ‘Varieties and
Species.’”




CHAPTER V.

DOWN--GEOLOGY OF THE VOYAGE--WORK ON CIRRIPEDES (1842–54).


From September 14th, 1842, until his death, Darwin resided at Down,
living a very retired life, and almost exclusively engaged in his
scientific researches. Although Down is only twenty miles from London,
it is three miles from the nearest railway station (Orpington), and is
only now for the first time receiving a telegraph office. A home in
such a place enabled Darwin to pursue his work without interruption,
remaining, at the same time, within easy reach of all the advantages of
London. Here, too, he had no difficulty in avoiding social engagements,
which always injured his very precarious health, and thus interfered
with work; although, at the same time, he could entertain in his own
house at such times as he felt able to do so.

In 1844, and again in 1846, he published works on the geology of the
voyage of the _Beagle_; the first on the Volcanic Islands visited, the
second on South America. A second edition, in which both were combined
in a single work, appeared in 1876. He seemed somewhat disappointed
at the small amount of attention they at first attracted, and wrote
with much humour to J. M. Herbert:--“I have long discovered that
geologists never read each other’s works, and that the only object in
writing a book is a proof of earnestness, and that you do not form
your opinions without undergoing labour of some kind.” All geologists
were, nevertheless, soon agreed in attaching the highest value to these
researches.

[Sidenote: ON CIRRIPEDES.]

From this time forward his work was almost exclusively zoological. The
four monographs on the Cirripedia, recent and fossil, occupied eight
years--from October, 1846, to October, 1854. The works on the recent
forms were published by the Ray Society (1851 and 1854), and those on
the fossil forms by the Palæontographical Society (1851 and 1854).
These researches grew directly out of his observations on the _Beagle_,
but it is evident that they reached far greater dimensions than he had
at first intended. Thus, at the very beginning of the work, he wrote
(October, 1846) to Hooker:--

      “I am going to begin some papers on the lower marine animals,
      which will last me some months, perhaps a year, and then I shall
      begin looking over my ten-year-long accumulation of notes on
      species and varieties, which, with writing, I dare say will take
      me five years, and then, when published, I dare say I shall stand
      infinitely low in the opinion of all sound Naturalists--so this
      is my prospect for the future.”

Darwin himself, at any rate towards the end of his life, when he
wrote his “Autobiography,” doubted “whether this work was worth
the consumption of so much time,” although admitting that it was
of “considerable value” when he had “to discuss in the ‘Origin of
Species’ the principles of a natural classification.” Sir Joseph Hooker
remembers that Darwin at an earlier time “recognised three stages
in his career as a biologist: the mere collector at Cambridge; the
collector and observer in the _Beagle_ and for some years afterwards;
and the trained naturalist after, and only after, the Cirripede work”
(Letter to F. Darwin).

Professor Huxley considers that just as by Darwin’s practical
experience of physical geography, geology, etc., on the _Beagle_, “he
knew of his own knowledge the way in which the raw materials of these
branches of science are acquired, and was, therefore, a most competent
judge of the speculative strain they would bear,” so his Cirripede work
fitted him for his subsequent speculations upon the deepest biological
problems. “It was a piece of critical self-discipline, the effect of
which manifested itself in everything your father wrote afterwards,
and saved him from endless errors of detail” (Letter to F. Darwin,
“Life and Letters”). The history of Darwin’s career has often been
used as an argument against those who, not having passed through a
similar training as regards systematic zoological work, have ventured
to concern themselves with the problems of evolution. Professor Meldola
has recently treated of this subject in his interesting presidential
address to the Entomological Society (1896). He says:--

      “It used formerly to be asserted that he only is worthy of
      attention who has done systematic, _i.e._ taxonomic, work.
      I do not know whether this view is still entertained by
      entomologists; if so, I feel bound to express my dissent. It
      has been pointed out that the great theorisers have all done
      such work--that Darwin monographed the Cirripedia, and Huxley
      the oceanic Hydrozoa, and it has been said that Wallace’s and
      Bates’s contributions in this field have been their biological
      salvation. I yield to nobody in my recognition of the value
      and importance of taxonomic work, but the possibilities of
      biological investigation have developed to such an extent
      since Darwin’s time that I do not think this position can any
      longer be seriously maintained. It must be borne in mind that
      the illustrious author of the ‘Origin of Species’ had none of
      the opportunities for systematic training in biology which any
      student can now avail himself of. To him the monographing of the
      Cirripedia was, as Huxley states in a communication to Francis
      Darwin, ‘a piece of critical self-discipline,’ and there can be
      no reasonable doubt that this value of systematic work will be
      generally conceded. That this kind of work gives the sole right
      to speculate at the present time is, however, quite another
      point.”

Meldola then goes on to argue that the systematic work of those who
know nothing of the living state of the species they are describing
does not specially fit them for theorising, and he concludes by quoting
the following passage from a letter recently received from A. R.
Wallace:--

      “I do not think species-describing is of any special use to the
      philosophical generaliser, but I do think the collecting, naming,
      and classifying some extensive group of organisms is of great
      use, is, in fact, almost essential to any thorough grasp of the
      whole subject of the evolution of species through variation
      and natural selection. I had described nothing when I wrote my
      papers on variation, etc. (except a few fishes and palms from the
      Amazon), but I had collected and made out species very largely
      and had seen to some extent how curiously useful and protective
      their forms and colours often were, and all this was of great use
      to me.”

Towards the end of this long period of hard taxonomic labour, we know
from Darwin’s letters that he was extremely tired of the work; but
with marvellous resolution--and in spite of the trouble of his health,
which was perhaps worse than at any other time--he clung to and carried
through this stupendous task, although all the time attracted away from
it by the weightier problems which he could never thrust aside after
they had once made their claim upon him.

[Sidenote: ON NAMING SPECIES.]

Darwin was evidently greatly disconcerted at the task of making out
those special difficulties which man has added to the difficulties of
Nature herself--the disheartening tangle of nomenclature. He thought
that the custom of appending the name of the systematist after that of
the species or genus he had named was injurious to the interests of
science--inducing men to name quickly rather than describe accurately.
Some of his remarks on this subject indicate the state of his mind.
Thus he wrote to Hooker, October 6th, 1848:--

      “I have lately been trying to get up an agitation ... against
      the practice of Naturalists appending for perpetuity the name
      of the _first_ describer to species. I look at this as a direct
      premium to hasty work, to _naming_ instead of _describing_. A
      species ought to have a name so well known that the addition of
      the author’s name would be superfluous, and ... empty vanity....
      Botany, I fancy, has not suffered so much as zoology from mere
      _naming_; the characters, fortunately, are more obscure.... Why
      should Naturalists append their own names to new species, when
      Mineralogists and chemists do not do so to new substances?”

And again he wrote to Hugh Strickland, January 29th, 1849:--

      “I have come to a fixed opinion that the plan of the first
      describer’s name, being appended for perpetuity to a species, has
      been the greatest curse to Natural History.... I feel sure as
      long as species-mongers have their vanity tickled by seeing their
      own names appended to a species, because they miserably described
      it in two or three lines, we shall have the same _vast_ amount of
      bad work as at present, and which is enough to dishearten any man
      who is willing to work out any branch with care and time.”

And in another letter (February 4th) to the same correspondent:--

      “In mineralogy I have myself found there is no rage to merely
      name; a person does not take up the subject without he intends
      to work it out, as he knows that his _only_ claim to merit rests
      on his work being ably done, and has no relation whatever to
      _naming_.... I do not think more credit is due to a man for
      defining a species, than to a carpenter for making a box. But I
      am foolish and rabid against species-mongers, or rather against
      their vanity; it is useful and necessary work which must be done;
      but they act as if they had actually made the species, and it was
      their own property.”

A little later in the same year (1849) his health seems to have
determined him to give up the crusade, for he writes to Hooker (April
29th):--

      “With health and vigour, I would not have shewn a white feather,
      [and] with aid of half-a-dozen really good Naturalists, I
      believe something might have been done against the miserable and
      degrading passion of mere species naming.”

Anyone whose researches have been among the species of any much-worked
and much-collected zoological group will quite agree that synonymy is,
as Darwin found it, heart-breaking work; and although there may be
good reasons why the system of appending the describer’s name must be
retained, such a protest as that raised in these letters cannot fail to
do good in drawing attention to an abuse which is only too common, and
which introduces unnecessary difficulty and gratuitous confusion into
the study of Nature.

[Sidenote: DEATH OF HIS FATHER.]

His father, Dr. Darwin, died November 13th, 1848, at the age of
eighty-three, when he was so much out of health that he was unable to
attend the funeral. In 1851 he lost his little daughter Annie, who died
at Malvern, April 23rd. A few days after her death he wrote a most
affecting account of her--a composition of great beauty and pathos.




CHAPTER VI.

THE GROWTH OF THE “ORIGIN OF SPECIES” (1837–58).


In dealing with this subject in his “Autobiography,” Darwin tells us
of his reflections whilst on the voyage of the _Beagle_, and here
mentions another observation which deeply impressed him in addition
to those which he again repeats, on the relation between the living
and the dead in the same area and on the productions of the Galapagos
Archipelago--viz. “the manner in which closely allied animals replace
one another in proceeding southwards over the continent” (of South
America). On the theory of separate creation the existence of such
representative species received no explanation, although it became
perfectly intelligible on the theory that a single species may be
modified into distinct, although nearly related, species in the course
of its range over a wide geographical area. Here, too, the evidence
is in favour of evolution simply, and does not point to any cause of
evolution.

He also implies that even at this time he regarded the beautiful
adaptations or contrivances of nature by which organisms are fitted
to their habits of life--“for instance, a woodpecker or a tree-frog
to climb trees, or a seed for dispersal by hooks or plumes”--as the
most striking and important phenomena of the organic world, and the
one great difficulty in the path of any naturalist who should attempt
to supply a motive force for evolution. And he regarded the previous
attempts at an explanation--the direct action of surroundings and the
will of the organism--as inadequate because they could not account for
such adaptations.

Therefore being convinced of evolution, but as yet unprovided with a
motive cause which in any way satisfied him, he began in July, 1837,
shortly after his return home from the _Beagle_, to collect all facts
which bore upon the modifications which man has induced in the animals
and plants which he has subjugated, following, as he tells us, the
example of Lyell in geology. He goes on to say in his “Autobiography”:--

      “I soon perceived that selection was the key-stone of man’s
      success in making useful races of animals and plants. But how
      selection could be applied to organisms living in a state of
      nature remained for some time a mystery to me.”

[Sidenote: COLLECTION OF NOTES.]

We see indications in the extracts from his note-book at this period
(viz. between July, 1837, and February, 1838), and before he had
arrived at the conception of Natural Selection, that he had the idea
of “laws of change” affecting species to some extent like the laws of
change which compel the individuals of every species to work out their
own development, the extinction of the one corresponding in a measure
to the death of the other. Thus he says, “It is a wonderful fact,
horse, elephant, and mastodon dying out about the same time in such
different quarters. Will Mr. Lyell say that some [same?] circumstance
killed it over a tract from Spain to South America? Never.” We know
that a few months later he would have himself accepted the view he
imputes to Lyell, and would have regarded the extinction as due to
some circumstance affecting the competition for food or some other
relationship with the organic life of the same district. It is probable
that the above quotation from his Diary was written in connection with
the conclusion of Chapter IX. of the first edition of the “Journal of
the Voyage” (pp. 211, 212); for the latter is a fuller exposition of
the same argument.[B]

      “One is tempted to believe,” he says, “in such simple relations,
      as variation of climate and food, or introduction of enemies,
      or the increased numbers of other species, as the cause of the
      succession of races. But it may be asked whether it is probable
      that [“than” is an evident misprint in the original] any such
      cause should have been in action during the same epoch over
      the whole northern hemisphere, so as to destroy the _Elephas
      primigenius_ on the shores of Spain, on the plains of Siberia,
      and in Northern America.... These cases of extinction forcibly
      recall the idea (I do not wish to draw any close analogy) of
      certain fruit-trees, which, it has been asserted, though grafted
      on young stems, planted in varied situations, and fertilized by
      the richest manures, yet at one period have all withered away and
      perished. A fixed and determined length of life has in such cases
      been given to thousands and thousands of buds (or individual
      germs), although produced in long succession.”

He then concludes that the animals of one species, although “each
individual appears nearly independent of its kind,” may be bound
together by common laws. He ends by arguing that the adaptations
of animals confined to certain areas cannot be related to the
peculiarities of climate or country, because other animals introduced
by man are often so much more successful than the aborigines. As to the
causes of extinction, “all that at present can be said with certainty
is that, as with the individual, so with the species, the hour of life
has run its course, and is spent.”

[Sidenote: EARLY VIEWS.]

At this time he had the conception--as we see in the succeeding
extracts from his Diary--of species being so constituted that they
must give rise to other species; or, if not, that they must die out,
just as an individual dies unrepresented if it has no offspring; that
change--and evidently change in some fixed direction--or extinction, is
inevitable in the history of a species after a certain period of time.
With this view, which presented much resemblance to that of the author
of the “Vestiges,” and which seemed uppermost in his mind at this time,
there are traces of others. Thus in one extract the “wish of parents”
was thought of as a very doubtful explanation of adaptation, while in
another we meet a tolerably clear indication of natural selection, a
variety which is not well adapted being doomed to extinction, while a
favourable one is perpetuated, the death of a species being regarded as
“a consequence ... of non-adaptation of circumstances.”

It seems certain that for fifteen months after July, 1837, he was
keenly considering the various causes of evolution which were
suggested to him by the facts of nature, and that some general idea of
natural selection presented itself to him at times, although without
any of the force and importance it assumed in his mind at a later time.

In October, 1838, he read “Malthus on Population,” and as he says:--

      “Being well prepared to appreciate the struggle for existence
      which everywhere goes on from long-continued observation of the
      habits of animals and plants, it at once struck me that under
      these circumstances favourable variations would tend to be
      preserved, and unfavourable ones to be destroyed. The result of
      this would be the formation of new species. Here then I had a
      theory by which to work.”

[Sidenote: SKETCH OF THE “ORIGIN.”]

In June, 1842, he wrote a brief account of the theory, occupying
thirty-five pages. In Lyell’s and Hooker’s introduction to the joint
paper by Darwin and Wallace in the Linnean Society’s Journal (1858) it
is stated that the first sketch was made in 1839, but Francis Darwin
shows (“Life and Letters,” 1887, Vol. II. pp. 11, 12) that in all
probability this is an error--a note of Darwin’s referring to the first
complete grasp of the theory after reading Malthus, being mistaken for
a reference to the first written account.

In 1844 the sketch was enlarged to a written essay occupying 231 pages
folio--“a surprisingly complete presentation of the argument afterwards
familiar to us in the ‘Origin of Species’” published fifteen years
later. Professor Huxley, after reading this essay, observed that “much
more weight is attached to the influence of external conditions in
producing variation, and to the inheritance of acquired habits than in
the ‘Origin,’” while Professor Newton pointed out that the remarks on
the migration of birds anticipate the views of later writers.[C]

The explanation of divergence of species during modification
(divergence of character) had not then occurred to him, and he tells us
in the “Autobiography”:--

      “I can remember the very spot in the road, whilst in my carriage,
      when to my joy the solution occurred to me; and this was long
      after I had come to Down. The solution, as I believe, is that
      the modified offspring of all dominant and increasing forms tend
      to become adapted to many and highly diversified places in the
      economy of nature.”

A good example of this tendency is seen in the relations of three great
vertebrate classes--mammals, birds, and fishes--to the environments for
which they are respectively fitted: earth, air, and water. Competition
is most severe between forms most nearly alike, and hence some measure
of relief from competition is afforded when certain members of each of
these classes enter the domain of one of the others. Hence, we observe
that although mammals as a whole are terrestrial, a small minority
are aërial and aquatic; although birds are aërial, a minority are
terrestrial and aquatic; although fishes are aquatic, a minority tend
to be, at any rate largely, terrestrial and aërial.

Huxley considered it “curious that so much importance should be
attached to this supplementary idea. It seems obvious that the theory
of the origin of species by natural selection necessarily involves
the divergence of the forms selected” (“Obituary,” 1888, reprinted
in “Darwiniana,” 1893; see pp. 280, 281). But Darwin showed that
divergence might be a great advantage in itself, and would then be
directly (and not merely incidentally and indirectly) encouraged and
increased by natural selection.

[Sidenote: RESOLVE TO PUBLISH.]

As soon as the 1844 sketch was finished, Darwin wrote a letter (July
5th) as his “solemn and last request” that his wife would, in the
case of his death, devote £400, or if necessary £500, in publishing
it, and would take trouble in promoting it. He suggests Lyell as the
best editor, then Edward Forbes, then Henslow (“quite the best in many
respects”), then Hooker (“would be _very_ good”), then Strickland.
After Strickland he had thought of Owen as “very good,” but added,
“I presume he would not undertake such a work.” If no editor could
be obtained, he requested that the essay should be published as it
was--stating that it was not intended for publication in its present
form. In August, 1854, he wrote on the back of the letter: “Hooker by
far best man to edit my Species volume.”

All this shows how certain he felt that he was on firm ground, and that
his theory of natural selection was of vast importance to science. This
same strong conviction appears clearly in the first edition of the
“Origin,” and is undoubtedly one of the secrets of its power to move
the minds of men. Although the author is above all others fair-minded;
although he is most keen to discover and to bring forward all opposing
evidence, and to criticise most minutely everything favourable;
nevertheless, looking at the evidence as a whole, he has no doubt as
to its bearing, and feels, and shows that he feels, a magnificent
confidence in the truth and the importance of his theory.




CHAPTER VII.

GROWTH OF THE “ORIGIN” (_continued_)--CORRESPONDENCE WITH FRIENDS.


The great periods of Darwin’s scientific career are marked by intimate
friendships, which must be taken into account in attempting to trace
his mental development. Henslow was his intimate friend at Cambridge
and during the voyage of the _Beagle_. The influence of Lyell, through
his writings, was of the utmost importance during the voyage, and was
deepened by the close personal contact which took place on Darwin’s
return. Sir Joseph Hooker was his most intimate friend during the
growth of the “Origin of Species.”

Although Hooker met Darwin in 1839, their friendship did not begin
until four years later, when the former returned from the Antarctic
Expedition. On January 11th, 1844, Darwin wrote admitting his
conclusions on the question of evolution:--“At last gleams of light
have come,” he says, “and I am almost convinced (quite contrary to the
opinion I started with) that species are not (it is like confessing a
murder) immutable” (“Life and Letters,” Vol. II. p. 23).

[Sidenote: INQUIRIES AND EXPERIMENTS.]

From this point onwards his letters, especially to Hooker, indicate
the course he was following and the various problems he was considering
as they arose. Thus we find that he had finished reading Wollaston’s
“Insecta Maderensia” in 1855 (writing March 7th), and had been struck
with the very large proportion of wingless beetles, and had interpreted
the observation, viz. “that powers of flight would be injurious to
insects inhabiting a confined locality, and expose them to be blown
to the sea.” It is of great interest thus to witness the origin of a
theory which has since been universally accepted, and has received
confirmation from many parts of the world.

On April 11th of the same year he is experimenting on the powers of
resistance to immersion in salt water possessed by seeds, and he
writes an account of it to Hooker. The object of these experiments was
to throw light on the means by which plants have been transported to
islands.

In the same year began his correspondence with Asa Gray, who soon
became one of his warmest friends. He had numerous questions to ask
about the geographical range of plants, and in 1857 he wrote explaining
in some detail the views at which he had arrived as to the causes of
evolution.

My friend Rowland H. Wedgwood, a nephew of Darwin, has given me
the following interesting letter to his father, which was written,
he believes, probably before 1855. By kind permission, it is here
published for the first time. The letter is of great interest, as
throwing light upon his work, and also because of this early reference
to Huxley:--

                                                  “Down, _Sept. 5_.

      “MY DEAR HARRY,--I am very much obliged for the Columbine seed
      and for your note which made us laugh heartily.

      “I had no idea what trouble the counting must have been, I had
      not the least conception that there would have been so many pods.
      I am very much interested on this point, and therefore to make
      assurance sure, I repeat your figures viz. 560 and 742 pods on
      two plants and 7200 on another. Does the latter number really
      mean pods and not seeds? Upon my life I am sorry to give so much
      trouble, but I should be VERY MUCH obliged for a few _average_
      size pods, put up separately that I may count the seeds in each
      pod: for though I counted the seeds in the pods sent before, I
      hardly dare trust them without counting more. Moreover I sadly
      want more seed itself for one of my experiments.

      “The young cabbages are coming up already. Thank you much about
      the asparagus seeds; as it is so rare a plant, you are my only
      chance.

      “We have been grieved to hear about poor Anne and Tom.--Your
      affect^{te} screw

                                                  “C. DARWIN.

      “Have you been acquainted with Mr. Huxley; I think you would find
      him a pleasant acquaintance. He is a very clever man.”

Mr. Francis Darwin believes that the asparagus and cabbage seeds were
for the experiments to determine the time during which immersion in
salt water could be endured. The object of such experiments was to
throw light on the means by which plants are distributed over the
earth’s surface. He also informs me that the use of the word “screw” is
unique and incomprehensible.

Darwin tells us in the “Autobiography” that “early in 1856 Lyell
advised me to write out my views pretty fully, and I began at once to
do so on a scale three or four times as extensive as that which was
afterwards followed in my ‘Origin of Species.’” This work he began on
May 14th, and, after working steadily until June, 1858, had written
about half the book, in ten chapters, when he received the celebrated
letter from Wallace, which altered everything.

[Sidenote: ON THE “ATLANTIS” THEORY.]

At this period we get interesting evidence of his extraordinary insight
in the strong protests he makes against the Atlantis hypothesis
of Edward Forbes, and the other vast continental extensions which
naturalists did not hesitate to make in order to explain the existence
of species common to countries separated by wide tracts of the ocean.
These lost continents were as generally accepted as they were freely
proposed. And yet we find that, even then, one thinker far ahead of his
time saw clearly enough--as the _Challenger_ Expedition twenty years
later proved beyond all doubt--that the geological evidence is against
such extension, and that the means of distribution possessed by animals
are such as to render the supposition unnecessary.

In June, 1856, he writes to Lyell: “My blood gets hot with passion and
turns cold alternately at the geological strides, which many of your
disciples are taking”; and after mentioning the extension of continents
proposed by many leading naturalists, he says: “If you do not stop
this, if there be a lower region for the punishment of geologists, I
believe, my great master, you will go there. Why, your disciples in
a slow and creeping manner beat all the old Catastrophists who ever
lived! You will live to be the great chief of the Catastrophists.”
Lyell wrote disagreeing on the subject of continental extension; and
hence, on June 25th, 1856, Darwin replied in a long letter, giving
in detail his reasons for rejecting the hypothesis. He argued (1)
that the supposed extension of continents and fusion of islands would
be vast changes, giving the earth a new aspect, but that recent and
tertiary molluscs, etc., are distinct on opposite sides of the existing
continents; so that, although he did not doubt _great_ changes of level
in parts of continents, he concluded that “_fundamentally_ they stood
as barriers to the sea where they now stand” ever since the appearance
of living species; (2) that if a continent were nearly submerged, the
last remaining peaks would by no means always be volcanic, as are,
almost without exception, the oceanic islands; (3) that the amount of
subsidence which took place in continental areas during the Silurian
and Carboniferous periods--viz. during one tolerably uniform set of
beings--would not be enough to account for the depth of the ocean over
some parts of the site of the supposed submerged continents; (4) that
the supposed extensions are not consistent with the _absence_ of many
groups of animals--_e.g._ mammals, frogs, etc.--from islands.

These arguments did not convince Lyell; and they have only received
an almost universal acceptance after the confirmatory evidence
afforded by the voyage of the _Challenger_. Dredgings over many parts
of the ocean showed that all the continental deposits are collected
on a fringing shelf not more than 200 miles wide, and that beyond
this in the ocean bed proper an entirely different kind of deposit is
accumulating, composed of the shells, bones, and teeth of swimming or
floating organisms, or the products of their decomposition, of volcanic
and cosmic dust, and the products--_e.g._ manganese dioxide--of the
decomposition of these and of floating pumice. Hence, the depths of the
ocean afford no indications of a lost continental area, but are covered
by a peculiar deposit unknown among the rocks of continents which were
formed in comparatively shallow water round and not far from coasts, or
in land-locked or nearly land-locked seas like the Mediterranean.

[Sidenote: EARLY CORRESPONDENCE.]

On July 20th, 1856, he wrote to Asa Gray, giving some account of his
views, and stating his belief in evolution, but only hinting at natural
selection.

About this time we meet with evidence of the great difficulty with
which Darwin’s ideas were thoroughly understood, even by his intimate
friends, to whom he often wrote on the subject. Later on, when the
“Origin of Species” was published, although the arguments in favour
of natural selection were given in considerable detail, many years
passed before the theory itself was understood by the great body of
naturalists. This particular case of misunderstanding is of such great
interest that it is desirable to consider it in detail.

In the origin of new species by natural selection, the stress
of competition determines the survival of favourable individual
variations, and these, when by the continued operation of the
process they have become constant, are added to those pre-existing
characters of the species which are inherited from a remote past,
and are witnesses of the operation of natural selection from age to
age under ever-changing conditions of competition and variation. It
follows, therefore, that the origin of a species can only take place
once; for it is infinitely improbable that the same variation would
be independently submitted under the same conditions of competition,
and added to the mass of inherited characters independently gained in
two distinct lines by natural selection acting in the same manner upon
the same variations in the same order through all ages. Not only is it
inconceivable that the same species could arise by natural selection
from distinct lines of ancestry, but it is extremely improbable that
the same species could arise independently in more than one centre
among the individuals of a changing species; for in this case, too,
it is most unlikely that the same conditions of competition would
co-exist with the same favourable variations in the areas inhabited by
independent colonies of the same species.

[Sidenote: EARLY CRITICISM.]

Under other theories of evolution--direct action of environment,
supposed inherited effects of use and disuse, etc.--an independent
origin, even from quite distinct lines, would be probable; and we find,
accordingly, that those who would advance such theories believe in what
is called the “polyphyletic” origin of species (_e.g._ the horse), and
in the principle of “convergence” carried far enough to produce the
same complex character (_e.g._ vertebrate teeth) twice over without any
genetic connection between the forms in which the character appears.

Under natural selection, however, such a result would be infinitely
improbable, and hence this theory strongly supports, and indeed
explains, the theory of “specific centres,” viz. that each species
has arisen in one area only, and has spread from that into the other
areas over which it now occurs. This view was strongly held by Lyell
and Hooker after an exhaustive study of the facts then known as to the
geographical distribution of plants and animals; and yet both of these
distinguished naturalists seem to have feared that Darwin, in advancing
a theory which was entirely consistent with their convictions and
utterly inconsistent with any other views upon the same subject, was in
some way undermining the conclusions at which they had arrived.

Thus Lyell wrote (July 25th, 1856) to Hooker:--

      “I fear much that if Darwin argues that species are phantoms,
      he will also have to admit that single centres of dispersion
      are phantoms also, and that would deprive me of much of the
      value which I ascribe to the present provinces of animals and
      plants, as illustrating modern and tertiary changes in physical
      geography.”

And on August 5th of the same year Darwin replied to Hooker, who had
apparently argued that the origin of species by direct action of
climate, etc., would mean independent and multiple specific centres:--

      “I see from your remarks that you do not understand my notions
      (whether or no worth anything) about modification; I attribute
      very little to the direct action of climate, etc. I suppose, in
      regard to specific centres, we are at cross purposes; I should
      call the kitchen garden in which the red cabbage was produced,
      or the farm in which Bakewell made the Shorthorn cattle,
      the specific centre of these _species_! And surely this is
      centralisation enough!”

As I have argued above, Darwin was all the time affording the strongest
support to the theory of specific centres: support which was entirely
wanting in the theory of separate creation, in which the origin of each
species is wrapped in mystery, so that we can form no opinion as to
whether it took place at one centre or at many.

At this time, when the views set forth in the “Origin” were gaining
shape and expression, we cannot estimate too highly the value of the
correspondence with Hooker. In after years, when the “Origin” had to
stand the fire of adverse criticism, and at first of very general
disapproval, it was of inestimable advantage that every idea contained
in it should have been minutely discussed beforehand with one who
was more critical and more learned than the greatest of those who
afterwards objected. Darwin tells us in his “Autobiography”:--

      “I think that I can say with truth that in after years, though I
      cared in the highest degree for the approbation of such men as
      Lyell and Hooker, who were my friends, I did not care much about
      the general public.”

But, although Darwin cared nothing for it, it is nevertheless true that
the approbation of minds such as these was a sure indication of the
general approbation of the intellect of the country, and of the world,
which was to follow as soon as the new ideas were absorbed.

[Sidenote: VALUE OF THE DISCUSSION.]

And the value which Darwin himself placed on these discussions appears
again and again in his letters. To take a single example, he writes to
Hooker November 23rd, 1856:--

      “I fear I shall weary you with letters, but do not answer this,
      for in truth and without flattery, I so value your letters,
      that after a heavy batch, as of late, I feel that I have been
      extravagant and have drawn too much money, and shall therefore
      have to stint myself on another occasion.”




CHAPTER VIII.

DARWIN AND WALLACE (1858).


The history of Darwin’s friendship with Alfred Russel Wallace is of
quite unique interest, being brought about by the fact that both
naturalists saw in evolution and its causes the great questions of the
immediate future, and by the agreement in the interpretations which
they independently offered. Wallace was collecting and observing in
the Malay Archipelago, and wrote to Darwin as the one man most likely
to sympathise with and understand his views and to offer valuable
criticism.

In the “Annals and Magazine of Natural History” for 1855, Wallace
published a paper “On the Law that has Regulated the Introduction
of New Species,” and in this and a letter written from the Malay
Archipelago Darwin recognised the similarity of their views, although
the completeness of this agreement was to be brought before him with
startling force a year after his sympathetic reply, written May 1st,
1857. He then wrote:--

      “By your letter and even still more by your paper in the Annals,
      a year or more ago, I can plainly see that we have thought much
      alike and to a certain extent have come to similar conclusions.
      In regard to the Paper in the Annals, I agree to the truth of
      almost every word of your paper; and I dare say that you will
      agree with me that it is very rare to find oneself agreeing
      pretty closely with any theoretical paper; for it is lamentable
      how each man draws his own different conclusions from the very
      same facts.”

On December 22nd he replied to another letter from Wallace, again
expressing agreement with all his conclusions except that upon the
supposed continental extension to oceanic islands, on which, alluding
to his previous discussion, he says:--

      “You will be glad to hear that neither Lyell nor Hooker thought
      much of my arguments. Nevertheless, for once in my life, I dare
      withstand the almost preternatural sagacity of Lyell.”

And he concludes with the wish--

      “May all your theories succeed, except that on Oceanic Islands,
      on which subject I will do battle to the death.”

He also said, as regards Wallace’s conclusions: “I believe I go
much further than you; but it is too long a subject to enter on my
speculative notions.”

[Sidenote: WALLACE’S ESSAY.]

Finally, on June 18th, 1858, Darwin received from Wallace a manuscript
essay bearing the title “On the Tendency of Varieties to depart
indefinitely from the Original Type.” Upon this essay he wanted
Darwin’s opinion, and asked him, if he thought well of it, to forward
it to Lyell. Darwin was startled to find in the essay a complete
account of his own views. That very day he wrote to Lyell, enclosing
the essay. In the letter he said:--

      “Your words have come true with a vengeance--that I should
      be forestalled. You said this, when I explained to you here
      very briefly my views of ‘Natural Selection’ depending on the
      struggle for existence. I never saw a more striking coincidence;
      if Wallace had my MS. sketch written out in 1842, he could not
      have made a better short abstract! Even his terms now stand as
      heads of my chapters.”

A few days later (June 25th) he again wrote to Lyell, saying--

      “I should be extremely glad now to publish a sketch of my general
      views in about a dozen pages or so; but I cannot persuade
      myself that I can do so honourably. Wallace says nothing about
      publication, and I enclose his letter. But as I had not intended
      to publish any sketch, can I do so honourably, because Wallace
      has sent me an outline of his doctrine? I would far rather burn
      my whole book, than that he or any other man should think that I
      had behaved in a paltry spirit.”

He also asked Lyell to send the letter on to Hooker, “for then I shall
have the opinion of my two best and kindest friends.” He was so much
distressed at the idea of being unfair to Wallace that he wrote again
the next day to put the case against himself in an even stronger light.
This must have been one of the most trying times in Darwin’s life, for,
in addition to the cause of trouble and perplexity described above, one
of his children died of scarlet fever, and there was the gravest fear
lest the others should be attacked.

[Sidenote: BOTH ESSAYS PUBLISHED.]

Thus appealed to, Lyell and Hooker took an extremely wise and fair
course. They asked Darwin for an abstract of his work, and, accepting
the whole responsibility, communicated it and Wallace’s essay in
a joint paper to the Linnean Society, giving an account of the
circumstances of the case in a preface, which took the form of a
letter to the Secretary of the Society. In this letter they introduced
to the Society “the results of the investigations of the indefatigable
naturalists, Mr. Charles Darwin and Mr. Alfred Wallace.”

      “These gentlemen having, independently and unknown to one
      another, conceived the same very ingenious theory to account for
      the appearance and perpetuation of varieties and of specific
      forms on our planet, may both fairly claim the merit of being
      original thinkers in this important line of enquiry; but neither
      of them having published his views, though Mr. Darwin has for
      many years past been repeatedly urged by us to do so, and both
      authors having now unreservedly placed their papers in our hands,
      we think it would best promote the interests of science that a
      selection from them should be laid before the Linnean Society.”

After giving a list of these selections, they say of Wallace’s essay--

      “This was written at Ternate[D] in February, 1858, for the
      perusal of his friend and correspondent Mr. Darwin, and sent
      to him with the expressed wish that it should be forwarded to
      Sir Charles Lyell, if Mr. Darwin thought it sufficiently novel
      and interesting. So highly did Mr. Darwin appreciate the value
      of the views therein set forth, that he proposed, in a letter
      to Sir Charles Lyell, to obtain Mr. Wallace’s consent to allow
      the Essay to be published as soon as possible. Of this step we
      highly approved, provided Mr. Darwin did not withhold from the
      public, as he was strongly inclined to do (in favour of Mr.
      Wallace), the memoir which he had himself written on the same
      subject, and which, as before stated, one of us had perused in
      1844, and the contents of which we had both of us been privy
      to for many years. On representing this to Mr. Darwin, he gave
      us permission to make what use we thought proper of his memoir,
      &c.; and in adopting our present course, of presenting it to the
      Linnean Society, we have explained to him that we are not solely
      considering the relative claims to priority of himself and his
      friend, but the interests of science generally; for we feel it to
      be desirable that views founded on a wide deduction from facts,
      and matured by years of reflection, should constitute at once a
      goal from which others may start, and that, while the scientific
      world is waiting for the appearance of Mr. Darwin’s complete
      work, some of the leading results of his labours, as well as
      those of his able correspondent, should together be laid before
      the public.”

The title of the joint paper was “On the Tendency of Species to form
Varieties; and on the Perpetuation of Varieties and Species by Natural
Means of Selection.” It was read July 1st, 1858.




CHAPTER IX.

DARWIN’S SECTION OF THE JOINT MEMOIR READ BEFORE THE LINNEAN SOCIETY
JULY 1, 1858.


[Sidenote: FIRST PUBLISHED ESSAY.]

The first section of Darwin’s communication consisted of extracts
from the Second Chapter of the First Part of his manuscript essay of
1844. The Part was entitled “The Variation of Organic Beings under
Domestication, and in their Natural State,” and the Second Chapter was
headed “On the Variation of Organic Beings in a State of Nature; on
the Natural Means of Selection; on the Comparison of Domestic Races
and True Species.” The extracts first deal with the tendency towards
rapid multiplication and the consequent struggle for life. The average
constancy of the numbers of individuals is traced to the average
constancy of the amount of food, “whereas the increase of all organisms
tends to be geometrical.” Practical illustrations are given in the
enormous increase of the mice in La Plata during the drought which
killed millions of cattle, and in the well-known and rapid increase
of the animals and plants introduced by man into a new and favourable
country.

The checks which operate when the country is stocked and the species
reaches its average are most difficult to detect, but none the less
certain. If any check is lightened in the case of any organism it will
at once tend to increase. “Nature may be compared to a surface on which
rest ten thousand sharp wedges touching each other and driven inward by
incessant blows.” Darwin meant by this image to express that just as
any single wedge would instantly rise above the rest when the blows on
it were in any way lessened as compared with those on the other wedges,
so it would be with the proportionate number of any species when the
checks to which it is subjected are in any way relaxed.

If the external conditions alter, and the changes continue progressing,
the inhabitants will be less well adapted than formerly. The changed
conditions would act on the reproductive system and render the
organisation plastic. Now, can it be doubted, from the struggle each
individual has to obtain subsistence, that any minute variation in
structure, habits, or instincts adapting that individual better to the
new conditions would tell upon its vigour and health? “Yearly more are
bred than can survive; the smallest grain in the balance, in the long
run, must tell on which death shall fall, and which shall survive.” If
this went on for a thousand generations who will deny its effect “when
we remember what, in a few years, Bakewell effected in cattle, and
Western in sheep, by this identical principle of selection?”

He gives an imaginary example of a canine animal preying on rabbits and
hares. If the rabbits, constituting its chief food, gradually became
rarer, and the hares more plentiful, the animal would be driven to
try and catch more hares, and hence would be selected in the direction
of speed and sharp eyesight. “I can see no more reason to doubt that
these cases in a thousand generations would produce a marked effect,
and adapt the form of the fox or dog to the catching of hares instead
of rabbits, than that greyhounds can be improved by selection and
careful breeding.” So also with plants having seeds with rather more
down, leading to wider dissemination. Darwin here added this note: “I
can see no more difficulty in this, than in the planter improving his
varieties of the cotton plant. C. D. 1858.”

Then follows a brief sketch of sexual selection and a comparison
with natural selection, and the conclusion is reached--“this kind
of selection, however, is less vigorous than the other; it does not
require the death of the less successful, but gives to them fewer
descendants. The struggle falls, moreover, at a time of year when food
is generally abundant, and perhaps the effect chiefly produced would
be the modification of the secondary sexual characters, which are not
related to the power of obtaining food, or to defence from enemies, but
to fighting with or rivalling other males.”

The second section was entitled “Abstract of a Letter from C. Darwin,
Esq., to Professor Asa Gray, Boston, U.S., dated Down, September 5th,
1857.” To this letter Darwin attached great importance as a convenient
and brief account of the essentials of his theory, written and sent to
Asa Gray many months before he received Wallace’s essay. A tolerably
full abstract of the letter, which is itself a very brief abstract,
is therefore printed below. The epitome here given is taken from the
letter itself, and is in certain respects more full than that published
in the Linnean Journal.

In the introductory parts Darwin explained that “the facts which
kept me longest scientifically orthodox are those of adaptation--the
pollen-masses in asclepias--the mistletoe, with its pollen carried by
insects, and seed by birds--the woodpecker, with its feet and tail,
beak and tongue, to climb the tree and secure insects. To talk of
climate or Lamarckian habit producing such adaptations to other organic
beings is futile. This difficulty I believe I have surmounted.” Having
then stated that the reasons which induced him to accept evolution
were “general facts in the affinities, embryology, rudimentary organs,
geological history, and geographical distribution of organic beings,”
he proceeds to give a brief account of his “notions on the means by
which Nature makes her species.” The following is an abstract of the
account he gives:--

[Sidenote: SUMMARY OF THE ESSAY.]

      I. The success with which selection has been applied by man in
      making his breeds of domestic animals and plants: and this even
      in ancient times when the selection was unconscious, viz. when
      breeding was not thought of, but the most useful animals and
      plants were kept and the others destroyed. “Selection acts only
      by the accumulation of very slight or greater variations,” and
      man in thus accumulating “_may be said_ to make the wool of one
      sheep good for carpets, and another for cloth, &c.”

      II. Slight variations of all parts of the organism occur in
      nature, and if a being could select with reference to the whole
      structure, what changes might he not effect in the almost
      unlimited time of which geology assures us.

      III. Animals increase so fast that, but for extermination,
      the earth would not hold the progeny of even the slowest
      breeding animal. Only a few in each generation can live; hence
      the struggle for life, which has never yet been sufficiently
      appreciated. “What a trifling difference must often determine
      which shall survive and which perish!” Thus is supplied the
      “unerring power” of “_Natural Selection_ ... which selects
      exclusively for the good of each organic being.”

      IV. If a country were changing the altered conditions would tend
      to cause variation, “not but what I believe most beings vary at
      all times enough for selection to act on.” Extermination would
      expose the remainder to “the mutual action of a different set of
      inhabitants, which I believe to be more important to the life
      of each being than mere climate.” In the infinite complexity
      of the struggle for life “I cannot doubt that during millions
      of generations individuals of a species will be born with
      some slight variation profitable to some part of its economy;
      such will have a better chance of surviving and propagating
      this variation, which again will be slowly increased by the
      accumulative action of natural selection; and the variety
      thus formed will either coexist with, or more commonly will
      exterminate its parent form.” Thus complex adaptations like those
      of woodpecker or mistletoe may be produced.

      V. Numerous difficulties can be answered satisfactorily in time.
      The supposed changes are only very gradual, and very slow, “only
      a few undergoing change at any one time.” The imperfection of
      the geological record accounts for deficient direct evidence of
      change.

      VI. Divergence during evolution will be an advantage. “The
      same spot will support more life if occupied by very diverse
      forms.” Hence during the increase of species into its
      offspring--varieties, or sub-species, or true species, the latter
      “will try (only few will succeed) to seize on as many and as
      diverse places in the economy of nature as possible,” and so
      will tend to “exterminate its less well-fitted parent.” This
      explains classification, in which the organic beings “always
      _seem_ to branch and sub-branch like a tree from a common trunk;
      the flourishing twigs destroying the less vigorous--the dead and
      lost branches rudely representing extinct genera and families.”

In a postscript he says:--

      “This little abstract touches only the accumulative power of
      natural selection, which I look at as by far the most important
      element in the production of new forms. The laws governing the
      incipient or primordial variation (unimportant except as the
      groundwork for selection to act on, in which respect it is all
      important), I shall discuss under several heads, but I can come,
      as you may well believe, only to very partial and imperfect
      conclusions.”

It is, I think, of especial interest to find Darwin at this early
period arguing in a most convincing manner for the creative power
of natural selection. The selective power becomes, by accumulation,
of such paramount importance in the process, as compared with the
variations, that, although these latter are absolutely essential, man
may be said to _make_ his domestic breeds and Nature her species. The
man who argued thus had been through and had left behind the difficulty
that, even now, is often raised--that “before anything can be selected
it must be,” and therefore that selection is of small account as
compared with variation.




CHAPTER X.

WALLACE’S SECTION OF THE JOINT MEMOIR READ BEFORE THE LINNEAN SOCIETY
JULY 1, 1858.


The communication by Alfred Russel Wallace was entitled “On the
Tendency of Varieties to depart indefinitely from the Original Type.”
An abstract of it is given below.

[Sidenote: WALLACE’S ESSAY.]

_Varieties_ produced in domesticity are more or less unstable, and
often tend to return to the parent form. This is usually thought to be
true for all varieties, and to be a strong argument for the original
and permanent distinctness of species.

On the other hand, races forming “permanent or true varieties” are
well known, and there are generally no means of determining which is
the _variety_ and which the original _species_. The hypothesis of a
“permanent invariability of species” is satisfied by supposing that,
while such varieties cannot diverge from the species beyond a certain
fixed limit, they may return to it.

This argument is founded on the assumption that _varieties_ in nature
are in all respects identical with those of domestic animals. The
object of the paper is to show that this is false, and “that there is
a general principle in nature which will cause many _varieties_ to
survive the parent species and to give rise to successive variations
departing further and further from the original type.” The same
principle explains the tendency of domestic animals to return to the
parent form.

“The life of wild animals is a struggle for existence.” To procure
food and escape enemies are the primary conditions of existence, and
determine abundance and rarity, frequently seen in closely allied
species.

“Large animals cannot be so abundant as small ones; the carnivora must
be less numerous than the herbivora,” eagles and lions than pigeons
and antelopes. Fecundity has little or nothing to do with this. The
least prolific animals would increase rapidly if unchecked. But wild
animals do not increase beyond their average; hence there must be an
immense amount of destruction. The abundance of species in individuals
bears no relation whatever to their fertility. Thus the excessively
abundant passenger pigeon of the United States lays only one or two
eggs. Its abundance is explained by the widespread supply of food
rendered available by its powers of flight. The food-supply “is almost
the sole condition requisite for ensuring the rapid increase of a
given species.” This explains why the sparrow is more abundant than
the red-breast, why aquatic species of birds are specially numerous
in individuals, why the wild cat is rarer than the rabbit. “So long
as a country remains physically unchanged, the numbers of its animal
population cannot materially increase.” If one species does so, others
must diminish. In the immense amount of destruction the weakest must
die, “while those that prolong their existence can only be the most
perfect in health and vigour--those who are best able to obtain food
regularly and to avoid their numerous enemies. It is, as we commenced
by remarking, ‘a struggle for existence,’ in which the weakest and
least perfectly organised must always succumb.”

This tendency must apply to species as well as individuals, the best
adapted becoming abundant, the others scarce or even extinct. If we
knew the whole of the conditions and powers of a species “we might be
able even to calculate the proportionate abundance of individuals,
which is the necessary result.”

Hence, first, _the animal population of a country is generally
stationary (due to food and other checks)_; second, _comparative
abundance or scarcity of individuals is entirely due to organisation
and resulting habits, the varying measure of success in the struggle
being balanced by a varying population in a given area_.

Variations from type must nearly always affect habits or capacities.
Even changes of colour may promote concealment, while changes in the
limbs or any external organs would affect the mode of procuring food,
etc. “An antelope with shorter or weaker legs must necessarily suffer
more from the attacks of the feline carnivora”; the passenger pigeon
with less powerful wings could not always procure sufficient food.
Hence species thus modified would gradually diminish; but, on the other
hand, if modified in the direction of increased powers, would become
more numerous. Varieties will fall under these two classes--those
which will never rival, and those which will eventually outnumber,
the parent species. If, then, some alteration in conditions occurred
making existence more difficult to a certain species, first the less
favourable variety would suffer and become extinct, then the parent
species, while the superior variety would alone remain, “and on a
return to favourable circumstances would rapidly increase in numbers
and occupy the place of the extinct species and variety.”

The superior _variety_ would thus replace the _species_, to which it
_could not_ return, for the latter could never compete with the former.
Hence a tendency to revert would be checked. But the superior variety,
when established, would in time give rise to new varieties, some of
which would become predominant. Hence _progression and continued
divergence_ would follow, but not invariably, for the criteria of
success or failure would vary, and would sometimes render a race
which was under other conditions the most favoured now the least so.
Variations without any effect on the life-preserving powers might also
occur. But it is contended that certain varieties must, on the average,
tend to persist longer than the parent species, while the scale on
which nature works is so vast that an average tendency must in the end
attain its full result.

Comparing domestic with wild animals, the very existence of the latter
depends upon their senses and physical powers. Not so with the former,
which are defended and fed by man.

Any favourable variety of a domestic animal is utterly useless to
itself; while any increase of the powers and faculties of wild animals
is immediately available, creating, as it were, a new and superior
animal.

Again, with domestic animals all variations have an equal chance, and
those which would be extremely injurious in a wild state are, under the
artificial conditions, no disadvantage. Our domestic breeds could never
have come into existence in a wild state, and if turned wild “_must_
return to something near the type of the original wild stock, _or
become altogether extinct_.”[E]

Hence we cannot argue from domestic to wild animals, the conditions of
life in the two being completely opposed.

Lamarck’s hypothesis of change produced by the attempts of animals to
increase the development of their own organs has been often refuted,
but the view here proposed depends upon the action of principles
constantly working in nature. Retractile talons of falcons and cats
have not been developed by volition, but by _the survival of those
which had the greatest facilities for seizing prey_. The long neck of
the giraffe was not produced by constant stretching, but by the success
which any increase in the length of neck ensured to its possessors.
Even colours, especially of insects, are explained in the same way,
for among the varieties of many tints, those “having colours best
adapted to concealment ... would inevitably survive the longest.” We
can similarly explain deficiency of some organs with compensating
development of others, “great velocity making up for the absence of
defensive weapons,” etc. Varieties with an unbalanced deficiency could
not long survive. The action of the principle is like the governor
of a steam-engine, checking irregularities almost before they become
evident. Such a view accords well with “the many lines of divergence
from a central type”; the increasing efficiency of a particular organ
in a series of allied species; the persistence of unimportant parts
when important ones have changed; the “more specialised structure,”
said by Owen to be characteristic of recent as compared with extinct
forms.

Hence there is a tendency of certain classes of _varieties_ to progress
further and further from the original type, and there is no reason for
assigning any limit to this progression. Such gradual changes “may,
it is believed, be followed out so as to agree with all the phenomena
presented by organised beings, their extinction and succession in past
ages, and all the extraordinary modifications of form, instinct, and
habits which they exhibit.”

Wallace’s Essay has been reprinted without any alteration in his
“Essays on Natural Selection,” recently re-issued combined with
“Tropical Nature.”




CHAPTER XI.

COMPARISON OF DARWIN’S AND WALLACE’S SECTIONS OF THE JOINT
MEMOIR--RECEPTION OF THEIR VIEWS--THEIR FRIENDSHIP.


[Sidenote: WALLACE AND DARWIN.]

Comparing the essays of these two naturalists, we observe that Darwin
here first makes public the phrase “natural selection,” Wallace the
“struggle for existence”; although so closely do their lines of thought
converge that Darwin, using practically the same words, speaks of
the “struggle for life.” Both show, by examples, the tendency of all
animals to multiply at an enormous rate, and both show that their
tolerably constant numbers are due to the constant supply of food.

Both treat of domesticated animals, but in very different ways. Darwin
uses them as the practical illustration of selection, and argues that
if man by selection can make such forms, Nature can make her species
by the same means. Wallace disposes of the argument that the reversion
of domesticated varieties to the wild form is a proof of the permanent
distinctness of species, by showing in some detail that the former are
“abnormal, irregular, artificial.”

Neither of them draws any distinction between instinct and other
qualities, but assumes that the former is, like the latter, operated
upon by natural selection.

Wallace makes a special point of protective resemblances in the colours
of insects, etc.

The important principle of “divergence of character,” and the
relatively unimportant one of “sexual selection,” are both clearly
explained by Darwin.

Neither writer speaks of the direct effect of external
conditions--except as a cause of plasticity by Darwin--or the inherited
effects of use and disuse. Lamarck is mentioned only to be dismissed
by Wallace. The evolution of the giraffe’s long neck is explained by
Wallace on the principle of natural selection, which is contrasted with
Lamarck’s original explanation of the same character. This contrast,
which has been so often drawn, was therefore originally contained in
the first public statement of natural selection.

As has been indicated above, Darwin suggested a cause of variation in
the direct effect of changed external conditions on the reproductive
system.

In comparing the two essays it is not unnatural to conclude, as
Professor Osborn has done (“From the Greeks to Darwin,” 1894, p.
245), that the two writers held different views upon the material
utilised by natural selection in the production of new species, Darwin
relying upon the usual slight differences which separate individuals
and upon variations in single characters, Wallace upon fully formed
varieties--viz. individuals which departed conspicuously from the type
of the species, and which may exist singly or in considerable numbers
side by side with the parent form.

Professor Osborn’s actual words are as follows:--

      “Darwin dwells upon _variations in single characters_, as taken
      hold of by Selection; Wallace mentions variations, but dwells
      upon _full-formed varieties_, as favourably or unfavourably
      adapted. It is perfectly clear that with Darwin the struggle is
      so intense that the chance of survival of each individual turns
      upon a single and even slight variation. With Wallace, varieties
      are already presupposed by causes which he does not discuss,
      a change in the environment occurs, and those varieties which
      happen to be adapted to it survive. There is really a wide gap
      between these two statements and applications of the theory.”

Further consideration tends to obliterate this supposed distinction.
Although Wallace used the term “variety” as contrasted with “species,”
the whole context proves that he, equally with Darwin, recognised
the importance of individual variations and of variations in single
characters. This becomes clear when we remember his argument about the
neck of the giraffe, the changes of colour and hairiness, the shorter
legs of the antelope, and the less powerful wings of the passenger
pigeon. Wallace has kindly written to me (May 12th, 1896) stating the
case as I have given it, and he further explains--

      “I used the term ‘varieties’ because ‘varieties’ were alone
      recognised at that time, individ^l variability being ignored or
      thought of _no importance_. My ‘varieties’ therefore included
      ‘individual variations.’”

On the other hand, Darwin certainly included large single variations
(in other words, “varieties”) as well as ordinary individual
differences, among the material for natural selection, and he did not
abandon the former until he was convinced by the powerful reasoning of
Fleeming Jenkin (_North British Review_, June, 1867), who argued that
single large differences of a sudden and conspicuous kind (Darwin’s
“variations”) would certainly be swamped by intercrossing. Upon this
review of the “Origin” Francis Darwin says (“Life and Letters”)--

      “It is not a little remarkable that the criticisms which my
      father, as I believe, felt to be the most valuable ever made on
      his views should have come, not from a professed naturalist but
      from a Professor of Engineering.”

After reading this review, Darwin wrote to Wallace (January 22nd,
1869):--

      “I always thought individual differences more important than
      single variations, but now I have come to the conclusion that
      they are of paramount importance, and in this I believe I agree
      with you. Fleeming Jenkin’s arguments have convinced me.”

The ambiguity of this sentence evidently misled Wallace into believing
that the single variations were considered of paramount importance.
Darwin therefore wrote again (February 2nd):--

      “I must have expressed myself atrociously; I meant to say exactly
      the reverse of what you have understood. F. Jenkin argued in the
      ‘North British Review’ (June 1867) against single variations
      ever being perpetuated, and has convinced me, though not in
      quite so broad a manner as here put. I always thought individual
      differences more important; but I was blind and thought single
      variations might be preserved much oftener than I now see is
      possible or probable. I mentioned this in my former note merely
      because I believed that you had come to a similar conclusion,
      and I like much to be in accord with you. I believe I was mainly
      deceived by single variations offering such simple illustrations,
      as when man selects.”

From these two letters to Wallace we see that the latter was the first
to give up the larger variations in favour of ordinary individual
differences.

Darwin also wrote to Victor Carus on May 4th, 1869:--

      “I have been led to ... infer that single variations are even of
      less importance, in comparison with individual differences, than
      I formerly thought.”

There has been much misconception on this point, and a theory of
evolution by the selection of large single variations--a view held by
many, but not by Darwin--has been passed off as the Darwinian theory of
natural selection. It is surprising that this old mistake should have
been repeated at so recent a date, and on so important an occasion as
the Presidential Address to the British Association at Oxford on August
8th, 1894, and that so ill-aimed a criticism should have been quoted
with approval in a leading article in the _Times_ of the following day.
The following extracts from Lord Salisbury’s address unfortunately
leave no doubt on the matter:

[Sidenote: LORD SALISBURY’S CRITICISM.]

      “What is to secure that the two individuals of opposite sexes
      in the primeval forest, who have been both accidentally blessed
      with the same advantageous variation shall meet, and transmit by
      inheritance that variation to their successors?... The biologists
      do well to ask for an immeasurable expanse of time, if the
      occasional meetings of advantageously varied couples from age to
      age are to provide the pedigree of modifications which unite us
      to our ancestor the jelly-fish.... There would be nothing but
      mere chance to secure that the advantageously varied bridegroom
      at one end of the wood should meet the bride, who by a happy
      contingency had been advantageously varied in the same direction
      at the same time at the other end of the wood. It would be a
      mere chance if they ever knew of each other’s existence--a still
      more unlikely chance that they should resist on both sides all
      temptations to a less advantageous alliance. But unless they did
      so, the new breed would never even begin, let alone the question
      of its perpetuation after it had begun.”

It is of interest to reproduce Lord Salisbury’s words in close
proximity to Darwin’s real statements on the subject, as shown in the
letters to his friends--statements which are also expressed in many
places in his published works.

The joint paper was read before the Linnean Society on July 1st, 1858,
about a fortnight after Wallace’s essay had been received by Darwin.
There was no discussion, but the interest and excitement at the meeting
were very great, owing in large part to the influential support
with which the new theory came before the scientific world. Darwin
appreciated the importance of this support at its true value, for he
wrote to Hooker, July 5th:--

      “You must know that I look at it, as very important, for the
      reception of the view of species not being immutable, the fact of
      the greatest Geologist and Botanist in England taking _any sort
      of interest_ in the subject: I am sure it will do much to break
      down prejudices.”

In the following January Darwin received a letter from Wallace, and
his reply (on the 25th) shows how much relieved and pleased he was
at its generous spirit. Alluding to Lyell’s and Hooker’s action in
his “Autobiography” Darwin says:--“I was at first very unwilling
to consent, as I thought Mr. Wallace might consider my doing so
unjustifiable, for I did not then know how generous and noble was his
disposition.” It was this letter which conveyed the knowledge to him
and set his mind at rest on the subject.

Thus ended one of the most interesting and memorable episodes in the
history of science. It was sufficiently remarkable that two naturalists
in widely-separated lands should have independently arrived at the
theory which was to be the turning-point in the history of biology
and of many other sciences--although such simultaneous discoveries
have been known before; it was still more remarkable that one of the
two should unknowingly have chosen the other to advise him upon the
theory which was to be for ever associated with both their names.
It was a magnificent answer to those who believed that the progress
of scientific discovery implies continual jealousy and bitterness,
that the conditions attending the first publication of the theory of
natural selection were the beginning of a life-long friendship and of
mutual confidence and esteem.[F]

[Sidenote: FRIENDSHIP WITH WALLACE.]

It is justifiable to speak of this episode as the _beginning_ of
Darwin’s and Wallace’s friendship, for the latter writes (February,
1895):--

      “I had met him _once_ only for a few minutes at the Brit. Mus.
      before I went to the East.”

Later on Darwin, in his letters to Wallace, more than once alluded to
the simultaneous publication of their essays. Thus he wrote, April
18th, 1869, congratulating Wallace on his article in the _Quarterly
Review_ for that month:--

      “I was also much pleased at your discussing the difference
      between our views and Lamarck’s. One sometimes sees the odious
      expression, ‘Justice to myself compels me to say,’ &c., but you
      are the only man I ever heard of who persistently does himself an
      injustice, and never demands justice. Indeed, you ought in the
      review to have alluded to your paper in the ‘Linnean Journal,’
      and I feel sure all our friends will agree in this. But you
      cannot ‘Burke’ yourself however much you may try, as may be seen
      in half the articles which appear.”

And again, on April 20th of the following year, he wrote:--

      “I hope it is a satisfaction to you to reflect--and very few
      things in my life have been more satisfactory to me--that we have
      never felt any jealousy towards each other, though in one sense
      rivals. I believe that I can say this of myself with truth, and I
      am absolutely sure that it is true of you.”




CHAPTER XII.

THE GROWTH OF WALLACE’S CONVICTIONS ON EVOLUTION AND DISCOVERY OF
NATURAL SELECTION--BORNEO 1855--TERNATE 1858.


We have already seen in the earlier part of this volume, the gradual
development of the theory of Natural Selection in the mind of Darwin,
and the long succession of experiments and observations which he
undertook before he could bring himself to publish anything upon the
subject, as well as the conditions which forced him to a hurried
publication in the end. It is of the deepest interest to compare with
this the account which Wallace has given us of the mental process by
which he arrived at the same conclusions.

This deeply interesting personal history has only been known during
the last few years; in 1891 Wallace republished his “Essays on Natural
Selection” in one volume, combined with “Tropical Nature,” and he has
added (on pp. 20, 21) the following introductory note to Chapter II.,
viz. the reprint of his Linnean Society Memoir “On the Tendencies of
Varieties to depart indefinitely from the Original Type.” The note is
here reprinted in full:--

      “As this chapter sets forth the main features of a theory
      identical with that discovered by Mr. Darwin many years before
      but not then published, and as it has thus an historical
      interest, a few words of personal statement may be permissible.
      After writing the preceding paper [“On the Law which has
      Regulated the Introduction of New Species”] the question of
      _how_ changes of species could have been brought about was
      rarely out of my mind, but no satisfactory conclusion was
      reached till February 1858. At that time I was suffering from
      a rather severe attack of intermittent fever at Ternate in the
      Moluccas, and one day, while lying on my bed during the cold
      fit, wrapped in blankets, though the thermometer was at 88°
      Fahr., the problem again presented itself to me, and something
      led me to think of the ‘positive checks’ described by Malthus
      in his ‘Essay on Population,’ a work I had read several years
      before, and which had made a deep and permanent impression on my
      mind. These checks--war, disease, famine and the like--must, it
      occurred to me, act on animals as well as man. Then I thought of
      the enormously rapid multiplication of animals, causing these
      checks to be much more effective in them than in the case of
      man; and while pondering vaguely on this fact there suddenly
      flashed upon me the _idea_ of the survival of the fittest--that
      the individuals removed by these checks must be on the whole
      inferior to those that survived. In the two hours that elapsed
      before my ague fit was over I had thought out almost the whole
      of the theory, and the same evening I sketched the draft of my
      paper, and in the two succeeding evenings wrote it out in full,
      and sent it by the next post to Mr. Darwin. Up to this time
      the only letters I had received from him were those printed in
      the second volume of his _Life and Letters_ (vol. ii., pp. 95
      and 108), in which he speaks of its being the twentieth year
      since he ‘opened his first note-book on the question how and
      what way do species and varieties differ from each other,’ and
      after referring to oceanic islands, the means of distribution
      of land-shells, &c., added: ‘My work, on which I have now been
      at work more or less for twenty years, _will not fix or settle
      anything_; but I hope it will aid by giving a large collection
      of facts, with one definite end.’ The words I have italicised,
      and the whole tone of his letters, led me to conclude that he
      had arrived at no definite view as to the origin of species,
      and I fully anticipated that my theory would be new to him,
      because it seemed to me to settle a great deal. The immediate
      result of my paper was that Darwin was induced at once to
      prepare for publication his book on the _Origin of Species_ in
      the condensed form in which it appeared, instead of waiting an
      indefinite number of years to complete a work on a much larger
      scale which he had partly written, but which in all probability
      would not have carried conviction to so many persons in so short
      a time. I feel much satisfaction in having thus aided in bringing
      about the publication of this celebrated book, and with the
      ample recognition by Darwin himself of my independent discovery
      of ‘natural selection.’ (See _Origin of Species_, 6th ed.,
      introduction, p. 1, and Life and Letters, vol. ii, chap. iv., pp.
      115–129 and 145).”

[Sidenote: ORIGIN OF WALLACE’S ESSAY.]

A very similar account, differing in a few unimportant details from
that quoted above, was written December 3rd, 1887, by Wallace to
Professor Newton, and is published in the abridged “Life and Letters of
Charles Darwin” (1892; pp. 189, 190). At the conclusion Wallace says:--

      “... I _had_ the idea of working it out, so far as I was able,
      when I returned home, not at all expecting that Darwin had so
      long anticipated me. I can truly say _now_, as I said many years
      ago, that I am glad it was so; for I have not the love of _work_,
      _experiment_ and _detail_ that was so pre-eminent in Darwin, and
      without which anything I could have written would never have
      convinced the world.”

It is of great interest to learn that Wallace as well as Darwin was
directed to natural selection by Malthus’ Essay. Hence, as the late
Professor Milnes Marshall has pointed out (Lectures on the Darwinian
Theory, pp. 212, 213), the laws of the multiplication and extinction
of man suggested to both naturalists those more general laws by which
it was possible to understand the development of the whole animal and
vegetable worlds.

There is a tremendous contrast between these two discoverers, in
the speed with which they respectively developed their ideas on the
subject into a shape which satisfied them as suitable for publication.
Wallace, after the inspiration which followed his reflections upon
Malthus, had “thought out almost the whole of the theory” in two hours,
and in three evenings had completed his essay. Darwin, receiving the
same inspiration from the same source, in October 1838, wrote a brief
account of it after four years’ reflection and work, and finished a
longer account two years later, but was not prepared to give anything
to the public until he was compelled to do so fourteen years later
in 1858. All this delay was of the greatest advantage when a full
exposition of the theory finally came before the world in the “Origin
of Species”; for all difficulties had been fully considered and
answered beforehand, while the wealth of new facts by which it was
supported compelled a respectful hearing for the theory itself.

[Sidenote: WALLACE’S VIEWS.]

Wallace, like Darwin, was convinced of evolution before he discovered
any principle which supplied a motive cause for the process. This
conviction is expressed very clearly in his interesting essay already
alluded to “On the Law which has regulated the Introduction of New
Species” (Ann. and Mag., Nat. Hist., 1855, p. 184; reprinted without
alteration in his Essays on Natural Selection). The law he states in
these words:--

      “Every species has come into existence coincident both in time
      and space with a pre-existing closely allied species,”

a law which, as he justly claims for it,

      “connects together and renders intelligible a vast number of
      independent and hitherto unexplained facts. The natural system of
      arrangement of organic beings, their geographical distribution,
      their geological sequence, the phenomena of representative and
      substituted groups in all their modifications, and the most
      singular peculiarities of anatomical structure, are all explained
      and illustrated by it, in perfect accordance with the vast mass
      of facts which the researches of modern naturalists have brought
      together, and, it is believed, not materially opposed to any of
      them. It also claims a superiority over previous hypotheses, on
      the ground that it not merely explains, but necessitates what
      exists. Granted the law, and many of the most important facts in
      Nature could not have been otherwise, but are almost as necessary
      deductions from it, as are the elliptic orbits of the planets
      from the law of gravitation.”

This important essay is dated by Wallace from Sarawak, Borneo,
February, 1855.

The conclusions remind us of the words Darwin wrote in his note-book in
1837. “Led to comprehend true affinities. My theory would give zest to
recent and Fossil comparative Anatomy.” By his theory Darwin here means
evolution and not natural selection, which was not discovered by him
until the end of 1838.




CHAPTER XIII.

CANON TRISTRAM THE FIRST PUBLICLY TO ACCEPT THE THEORY OF NATURAL
SELECTION (1859).


Although the historic meeting at the Linnean Society appeared to
produce but little effect, one distinguished naturalist publicly
accepted the theory of natural selection before the publication of “The
Origin of Species,” and therefore as the direct result of Darwin’s
and Wallace’s joint paper. This great distinction belongs to Canon
Tristram, as Professor Newton has pointed out in his Presidential
Address to the Biological Section of the British Association at
Manchester in 1887 (“Reports,” p. 727), at the same time expressing the
hope “that thereby the study of Ornithology may be said to have been
lifted above its fellows.”

[Sidenote: CANON TRISTRAM’S SUPPORT.]

Canon Tristram’s paper, “On the Ornithology of Northern Africa” (Part
iii., The Sahara, continued), was published in _The Ibis_, vol. i.,
October, 1859. The important conclusions alluded to above are contained
at the end of the section upon the species of desert larks (pp.
429–433):

      “Writing with a series of about 100 larks of various species from
      the Sahara before me, I cannot help feeling convinced of the
      truth of the views set forth by Messrs. Darwin and Wallace in
      their communications to the Linnean Society, to which my friend
      Mr. A. Newton last year directed my attention.... It is hardly
      possible, I should think, to illustrate this theory better than
      by the larks and chats of North Africa. In all these birds we
      trace gradual modifications of coloration and of anatomical
      structure, deflecting by very gentle gradations from the ordinary
      type; but when we take the extremes, presenting most marked
      differences.”

These differences, he concludes--

      “have a very direct bearing on the ease or difficulty with which
      the animal contrives to maintain its existence.”

He then points out, upon the uniform surface of the desert it is
absolutely necessary that animals shall be protected by their colour:

      “Hence, without exception, the upper plumage of every bird,
      whether Lark, Chat, Sylvian, or Sandgrouse, and also the fur
      of all the small mammals, and the skin of all the Snakes and
      Lizards, is of one uniform isabelline or sand colour. It is
      very possible that some further purpose may be served by the
      prevailing colours, but this appears of itself a sufficient
      explanation. There are individual varieties in depth of hue among
      all creatures. In the struggle for life which we know to be going
      on among all species, a very slight change for the better, such
      as improved means of escaping from its natural enemies (which
      would be the effect of an alteration from a conspicuous colour
      to one resembling the hue of the surrounding objects), would
      give the variety that possessed it a decided advantage over the
      typical or other forms of the species. Now in all creatures,
      from Man downwards, we find a tendency to transmit individual
      varieties or peculiarities to the descendants. A peculiarity
      either of colour or form soon becomes hereditary when there
      are no counteracting causes, either from change of climate or
      admixture of other blood. Suppose this transmitted peculiarity
      to continue for some generations, especially when manifest
      advantages arise from its possession, and the variety becomes not
      only a race, with its variations still more strongly imprinted
      upon it, but it becomes the typical form of that country.”

Canon Tristram then points out the manner in which he imagines that one
of the crested larks of the desert has been produced by the survival
of the lightest coloured individuals, _Galerida abyssinica_ only
differing in this respect from _G. cristata_ of Europe. Short-billed
species of the same genus inhabiting hard rocky districts, and
long-billed inhabiting loose sandy tracts have, he believes, been
produced by the survival in each case of the forms of bill most suited
to procure food:

      “Here are only two causes enumerated which might serve to
      _create_ as it were a new species from an old one, yet they
      are perfectly natural causes, and such as, I think, must have
      occurred, and are possibly occurring still. We know so very
      little of the causes which in the majority of cases make
      species rare or common, that there may be hundreds of others
      at work, some even more powerful than these, which go to
      perpetuate and eliminate certain forms ‘according to natural
      means of selection.’ But even these superficial causes appear
      sufficient to explain the marked features of the Desert races,
      which frequently approach so very closely the typical form, and
      yet possess such invariably distinctive characteristics, that
      naturalists seem agreed to elevate them to the rank of species.”

Although the author also declares his belief in the special creation
of many species--a view put forward as possible by Darwin in the
“Origin”[G]--and also believed in some direct influence of locality,
climate, etc., the above quoted passages are a most complete acceptance
of natural selection, at the same time affording excellent examples of
its operation.




CHAPTER XIV.

THE PREPARATION OF “THE ORIGIN OF SPECIES” (1858–59).


Almost immediately after the Linnean Society meeting, and evidently
earlier than September, the time mentioned in his “Autobiography,”
Darwin began to prepare a longer and more complete account of his work
on evolution and natural selection. This account was at first intended
for the Linnean Society, but it was soon found to be too long, and he
then decided to publish it as an independent volume. In thus preparing
the manuscript for what afterwards became the “Origin of Species,”
Darwin tells us (“Autobiography”) he acted under “the strong advice of
Lyell and Hooker,” and his letters also show the great interest that
they were taking in the work.

Darwin seems to have found the “Origin”--or his “Abstract,” as he
always calls it--very hard work, and he ends his letter to Wallace
(January 25th, 1859) with the words:

      “I look at my own career as nearly run out. If I can publish my
      Abstract and perhaps my greater work on the same subject, I shall
      look at my course as done.”

At the same time, so great was his enthusiasm and interest, in spite
of the hard work and ill-health, that all through this period he was
making fresh observations whenever an opportunity occurred. Thus we
find him writing to Hooker about the thistle-down blown out to sea and
then back to shore again; about the migrations of slave-making ants
which he had been watching; about the bending of the pistil into the
line of the gangway leading to the honey when this latter “is secreted
at one point of the circle of the corolla,” etc. And on March 2nd,
1859, he writes about “an odd, though very little, fact”:--Large nuts
had been found in the crops of some nestling Petrels at St. Kilda,
which he suspected the parent birds had picked up from the Gulf Stream.
He arranged for one of these to be sent, and asked Hooker for the name
and country. He asks forgiveness for the trouble, “for it is a funny
little fact after my own heart.” The nuts turned out to be West Indian.

When the proposal for publication had been accepted by Murray and the
manuscript was assuming its final form, the letters to Hooker were more
frequent than ever. Writing on May 11th, 1859, Darwin again raises the
question of the relative importance of variation and selection.

      “I imagine from some expressions ... that you look at variability
      as some necessary contingency with organisms, and further that
      there is some necessary tendency in the variability to go on
      diverging in character or degree. _If you do_, I do not agree.”

Darwin’s splendid confidence in the future appears in a letter written
about this time (September 2, 1859) in which he begs Lyell not to
commit himself “to go a certain length and no further; for,” he says,
“I am deeply convinced that it is absolutely necessary to go the whole
vast length, or stick to the creation of each separate species.” He
asks Lyell to remember that his verdict will probably be of more
importance than the book itself in influencing the present acceptance
or rejection of the views. “In the future,” he continues, “I cannot
doubt about their admittance, and our posterity will marvel as much
about the current belief as we do about fossil shells having been
thought to have been created as we now see them.” And again writing
to Lyell a few days later (September 20th), he says, “I cannot too
strongly express my conviction of the general truth of my doctrines,
and God knows I have never shirked a difficulty.”

I have thought it well to bring strong evidence of Darwin’s entire
confidence in his conclusions, because his writings were so
extraordinarily balanced and judicial, and the weight he gives to
opposing considerations so great, that a superficial student might
imagine that he wrote and argued without any very strong convictions.

The letters to Mr. John Murray, the publisher, are eminently
characteristic, in the expressions of regret for trouble given, and
of pleasure at the work done, in the scrupulous care to prevent the
publisher from feeling committed, if on further acquaintance with the
manuscript he did not wish to accept it, and in the offer to contribute
towards the cost of corrections.

[Sidenote: THE “ORIGIN” PUBLISHED.]

The first edition of “The Origin of Species” was published November
24th, 1859. The edition consisted of 1,250 copies, all of which were
sold on the day of issue.

The full title of this volume, of which Darwin justly says
(“Autobiography”), “It is no doubt the chief work of my life,” is
reproduced below.

                                  ON

                         THE ORIGIN OF SPECIES

                    BY MEANS OF NATURAL SELECTION,

                                OR THE

            PRESERVATION OF FAVOURED RACES IN THE STRUGGLE
                               FOR LIFE.

                       BY CHARLES DARWIN, M.A.,

      FELLOW OF THE ROYAL, GEOLOGICAL, LINNEAN, ETC., SOCIETIES;
   AUTHOR OF “JOURNAL OF RESEARCHES DURING H.M.S. ‘BEAGLE’S’ VOYAGE
                           ROUND THE WORLD.”

This title is of interest, as has been pointed out by Professor E. Ray
Lankester, in relation to the controversy upon the exact meaning of the
word “Darwinism.” Some writers have argued that the term “Darwinism”
includes the whole of the causes of evolution accepted by Darwin--the
supposed inherited effects of use and disuse and the direct influence
of environment, which find a subordinate place in the “Origin,” as
well as natural selection, which is the real subject of the book and
which is fully defined in the title. It would seem appropriate to
use the term “Darwinism,” as Wallace uses it, to indicate the causes
of evolution which were suggested by Darwin himself, excluding these
supposed causes which had been previously brought forward by earlier
writers, and especially by Lamarck. The causes of evolution proposed
by Lamarck are seriously disputed, and it is possible that they may
be ultimately abandoned. If so, the integrity of “Darwinism,” as
interpreted by some controversialists, would be impaired; and this, it
will be generally admitted, would be most unfortunate, as well as most
unfair to the memory of Darwin.




CHAPTER XV.

THE ORIGIN OF SPECIES (1859).


[Sidenote: THE ORIGIN OF SPECIES.]

It is very interesting to separate the two arguments which occur
interwoven in the “Origin”--the argument for evolution and the
argument for natural selection. The paramount importance of Darwin’s
contributions to the evidences of organic evolution are often forgotten
in the brilliant theory which he believed to supply the motive cause
of descent with modification. Organic evolution had been held to be
true by certain thinkers during many centuries; but not only were
its adherents entirely without a sufficient motive cause, but their
evidences of the process itself were erroneous or extremely scanty.
It was Darwin who first brought together a great body of scientific
evidence which placed the process of evolution beyond dispute, whatever
the causes of evolution may have been. And accordingly we find that,
even at first, natural selection was attacked far more generally than
the doctrine of descent with modification.

In Chapter I., Variation under Domestication and man’s power of
selection in forming breeds of animals and plants are discussed; in
Chapter II., Variation under Nature; in Chapter III., the Struggle for
Existence; in Chapter IV., which Darwin, in writing to his publisher,
called “the Keystone of my Arch,” the three preceding chapters are
carried to their conclusion, and the operation of natural selection
is explained and discussed. Hence, these four chapters deal almost
exclusively with this process.

Chapter V. has for its subject the Laws of Variation, and explains
causes of modification (external conditions, use and disuse,
correlation, reversion, etc.) other than natural selection and the
relation of the latter to the former.

In Chapter VI. difficulties are considered--partly those in the way
of a belief in evolution and partly those which, at first sight, seem
to be incapable of explanation on the theory of natural selection.
Chapter VII. deals with a special difficulty of the latter kind, viz.
Instinct, and shows how it can be accounted for by natural selection
acting upon variation, although allowing some weight to the inheritance
of habit. Chapter VIII. deals with Hybridism, the sterility of first
crosses and of hybrids being considered as an objection to the doctrine
of Descent with Modification. Chapter IX. treats of the Imperfection
of the Geological Record as the explanation of the apparently
insufficient evidence of evolution during past ages. Chapter X., on the
Geological succession of Organic Beings, shows that, allowing for this
Imperfection of Record, the facts brought to light by Geology support a
belief in evolution and in some cases even in natural selection. Hence
these five chapters deal partly with difficulties in the way of an
acceptance of organic evolution and partly with those encountered by
natural selection.

Of the three remaining chapters before the XIVth, and last, which
contains the Recapitulation and Conclusion, two--XI. and XII.--are
concerned with Geographical distribution, while the XIIIth deals with
Classification, Morphology, Embryology and Rudimentary Organs. These
three chapters are almost entirely devoted to the proof that the facts
of Nature with which they deal are not inconsistent with, but rather
support, and often strongly support, a belief in Organic Evolution.

Hence we see that this, incomparably the greatest work which the
biological sciences have seen, begins with an explanation and defence
and definition of the sphere of natural selection--then passes to
consider difficulties which are partly those of natural selection, and
partly of organic evolution--while it finally treats of the evidences
of the latter process and the difficulties which a belief in it
encounters.

This arrangement was a very wise one for a book which was intended to
convince a large circle of readers; for the human mind so craves after
an explanation, that it was of more importance for the success of the
work to show first that an intelligible cause of evolution had been
proposed, than to follow the more logical order of first setting forth
the evidences of evolution.

The second edition (fifth thousand) was issued in January, 1860, the
third (seventh thousand) in 1861, the fourth (eighth thousand) in 1866,
the fifth (tenth thousand) in 1869, the sixth in 1872: in 1887 the
twenty-fourth thousand was reached.

A note to the last edition states that the second “was little more
than a reprint of the first. The third edition was largely corrected
and added to, and the fourth and fifth still more largely.” The sixth
edition also contains “numerous small corrections,” and is about
one-fourth larger than the first edition, although this material is,
owing to the smaller print and more crowded lines, compressed into a
smaller number of pages. The sixth edition also differs from the first
in containing a glossary, an historical sketch, and a note and list of
the chief corrections.

The titles of Chapters I., II., and III. remain the same in the first
and last editions. Herbert Spencer’s phrase is added to Darwin’s
term, as the heading of Chapter IV., which accordingly becomes in the
last edition “Natural Selection; or the Survival of the Fittest.”
This change was certainly introduced in order to help readers to
grasp the meaning of Darwin’s title, which had been very generally
misunderstood. The heading of Chapter V. remains the same, while in
Chapter VI.--“Difficulties on Theory”--“on” is replaced by “of the.”
This chapter is, in the last edition, succeeded by a new one dealing
with many of the difficulties which had been raised or had occurred
to Darwin in the interval between the two editions; it is headed
“Miscellaneous Objections to the Theory of Natural Selection.” The
titles of the remaining eight chapters are unchanged.

The first part of the title of the first edition--“On the Origin of
Species”--becomes “The Origin of Species” in the last edition, and is
still further shortened to “Origin of Species” on the outside of the
volume.

The form of the earlier editions was admirably suited for the purpose
of attracting, and--so far as was possible with so difficult a
subject--convincing, a large number of readers. When the subject
was new and strange, the more numerous details of the last edition,
and the smaller print which became necessary, would have acted as a
hindrance to the complete success of the work. Authors and publishers
are sometimes apt to forget that the form of a book has a great deal to
do with the absorption of the ideas contained in it, especially when
the argument is from the nature of the case difficult to follow, and
the subject a new one. Francis Darwin in the “Life and Letters” justly
condemns the unattractive form of the sixth edition of the work.




CHAPTER XVI.

THE INFLUENCE OF DARWIN UPON LYELL (1859–64).


In considering the reception of the “Origin of Species,” it will
be well first to show its effect upon Darwin’s intimate scientific
friends, most of whom had been familiar with his work for many years,
and then to deal with its effects upon biologists generally, especially
those of Darwin’s own country.

The gradual strengthening of Darwin’s influence over his old teacher
Lyell, is one of the most interesting episodes in the personal history
of the scientific men of this century.

[Sidenote: LYELL’S SLOW CONVERSION.]

Lyell, after reading the proof-sheets of the “Origin,” wrote on
October 3rd, 1859, praising the work very warmly, and suggesting a few
improvements, some of which were adopted. Lyell hesitated to accept
the theory, because he saw clearly that it would be impossible to stop
short at the human species, while a common origin of men and beasts was
distasteful to him. Thus, he said:--

      “I have long seen most clearly that if any concession is made,
      all that you claim in your concluding pages will follow. It is
      this which has made me so long hesitate, always feeling that
      the case of man and his races, and of other animals, and that
      of plants is one and the same, and that if a ‘vera causa’ be
      admitted for one, instead of a purely unknown and imaginary one,
      such as the word ‘Creation,’ all the consequences must follow.”

To this letter Darwin replied (October 11th) at great length, in a most
instructive letter, arguing in considerable detail on all the points
alluded to by Lyell. He evidently thought that Lyell’s opinion was of
the utmost importance for the success of Natural Selection. “If ever
you are [perverted],” he wrote at the end of the letter, “I shall know
that the theory of Natural Selection is, in the main, safe.”

About this time Darwin seems to have heard that Lyell had made up his
mind to admit the doctrine of evolution into a new edition of the
“Manual,” and he wrote (November 23rd):--

      “I honour you most sincerely. 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.”

Lyell’s public confession of faith was, however, not to be made for
some years, and Darwin’s letter was a little premature.

Space will not permit me to quote from the long correspondence
with Lyell in the years following the appearance of the “Origin,”
although these letters are of the deepest interest, and deal in the
most luminous manner with the difficulties of natural selection and
evolution, as they appeared to one of the acutest intellects of that
time. The letters soon began to produce an effect, and Darwin wrote
(September 26th, 1860) to Asa Gray:--

      “I can perceive in my immense correspondence with Lyell, who
      objected to much at first, that he has, perhaps unconsciously to
      himself, converted himself very much during the last six months,
      and I think this is the case even with Hooker. This fact gives me
      far more confidence than any other fact.”

Later on Darwin evidently became a little annoyed that Lyell still
delayed to declare his belief one way or the other. Thus he wrote to
Asa Gray (May 11th, 1863):--

      “You speak of Lyell as a judge; now what I complain of is that
      he declines to be a judge.... I have sometimes almost wished
      that Lyell had pronounced against me. When I say ‘me,’ I only
      mean _change of species by descent_. That seems to me the
      turning-point. Personally, of course, I care much about Natural
      Selection; but that seems to me utterly unimportant, compared to
      the question of Creation _or_ Modification.”

Shortly before this date, on February 24th, he wrote to Hooker in
much the same style. These communications were called forth by the
appearance of “The Antiquity of Man,” and it is clear that Darwin’s
disappointment at Lyell’s suspended judgment was due to their
correspondence, which had encouraged him to expect some definite
opinion on the question. “From all my communications with him, I must
ever think that he has really entirely lost faith in the immortality
of species,” he wrote in his letter to Hooker. On March 6th he wrote
to Lyell himself, expressing his disappointment, and again a few days
later, rather complaining that his work was treated as a modification
of Lamarck’s:--

      “This way of putting the case ... closely connects Wallace’s and
      my views with what I consider, after two deliberate readings, as
      a wretched book, and one from which (I well remember my surprise)
      I gained nothing.”

When the second edition of “The Antiquity of Man” appeared in a few
months, there was a significant change in one sentence:--

      “Yet we ought by no means to undervalue the importance of the
      step which will have been made, should it hereafter become
      the generally received opinion of men of science (as I fully
      expect it will) that the past changes of the organic world have
      been brought about by the subordinate agency of such causes as
      Variation and Natural Selection.”

The words in parentheses had been added, and constituted Lyell’s first
public expression of an opinion in favour of Darwin’s views.

About this time an article appeared in the _Athenæum_ (March 28th,
1863), attacking the opinions in favour of evolution contained in
Dr. Carpenter’s work on Foraminifera, and supporting spontaneous
generation. This was one of the rare occasions on which Darwin entered
into controversy, and he wrote attacking spontaneous generation, and
pointing out the numerous classes of facts which are connected by
an intelligible thread of reasoning by means of his theory. In this
letter he quoted the altered sentence from the second edition of the
“Antiquity.” Darwin’s letter was answered in an article (May 2nd) in
which it was argued that _any_ theory of descent would connect the
various classes of facts equally well. To this Darwin replied in a
characteristic letter. It was evident that he was most reluctant to
continue the controversy, but thought it fair to admit publicly the
force of his opponent’s arguments.

[Sidenote: ACCESSION OF LYELL.]

In 1864 the Copley Medal of the Royal Society was given to Darwin. At
the anniversary dinner of the Society, after the meeting at which the
medals are presented by the President, Sir Charles Lyell in his speech
made a “confession of faith” as to the “Origin.” Darwin was prevented
by illness from receiving the medal in person and from being present at
the dinner.

The tenth edition of the “Principles” was published in 1867 and 1868,
and in it Lyell clearly stated his belief in evolution. Sir Joseph
Hooker, in his presidential address to the British Association at
Norwich in 1868, eloquently spoke of the “new foundation” with which
Lyell had under-pinned the edifice he had raised, and had thus rendered
it “not only more secure, but more harmonious in its proportion than
it was before.” Wallace, too, in an article in the _Quarterly Review_
(April, 1869), spoke with equal eloquence and force of the significance
of Lyell’s change of opinion.

Lyell’s death took place in 1875, eleven years after his definite
acceptance of Darwin’s views. Darwin, in writing to Miss Arabella
Buckley (now Mrs. Fisher, formerly secretary to Sir Charles Lyell),
fully acknowledged the deep debt which he owed to Lyell’s teachings:
“I never forget that almost everything which I have done in science
I owe to the study of his great works.” Huxley says in his obituary
of Charles Darwin (reprinted in “Darwiniana,” 1893, p. 268): “It is
hardly too much to say that Darwin’s greatest work is the outcome of
the unflinching application to Biology of the leading idea and the
method applied in the ‘Principles’ to Geology.” Every biologist who
realises--as who can help realising?--the boundless opportunities which
Darwin’s work has opened for him, will feel that he too owes a deep
personal debt to Darwin’s great teacher.




CHAPTER XVII.

INFLUENCE OF DARWIN UPON HOOKER AND ASA GRAY--NATURAL SELECTION AND
DESIGN IN NATURE (1860–68).


Hooker wrote on November 21st, speaking of the “glorious book” in the
warmest terms. Later on in the year he wrote again in the same spirit,
but speaking of the difficulty he found in assimilating the immense
mass of details: “It is the very hardest book to read, to full profits,
that I ever tried--it is so cram-full of matter and reasoning.” Hooker
must, however, have been familiar with the arguments and proofs,
and for this reason did not attempt any detailed discussion. It is
unnecessary to say more of Hooker’s reception of the “Origin.” During
their long friendship Darwin had discussed the difficulties and the
evidences of his theory more fully with him than with any other man;
and, as “a man sharpeneth the countenance of his friend,” the influence
of Hooker was one of the most potent forces under which Darwin produced
the greatest work of his life.

Many years later, when Hooker was awarded, in 1887, the Copley Medal
of the Royal Society, reviewing his past experiences and work in his
speech at the anniversary dinner, he concluded by telling us that his
long and intimate friendship with Charles Darwin was the great event of
his scientific career.

[Sidenote: ASA GRAY.]

In sending a copy to Asa Gray, he wrote (November 11th):--

      “I fully admit that there are very many difficulties not
      satisfactorily explained by my theory of descent with
      modification, but I cannot possibly believe that a false theory
      would explain so many classes of facts as I think it certainly
      does explain. On these grounds I drop my anchor, and believe that
      the difficulties will slowly disappear.”

Asa Gray’s reply was contained in a letter to Hooker, written January
5th, 1860, four days after reading the “Origin.” He asks that Darwin
may be told of what he had written. He says that the book “is done in
a _masterly manner_. It might well have taken twenty years to produce
it.” He expressed the intention of reviewing the book, and seeing that
Darwin and Hooker had fair play in America. A little later (January
23rd) he wrote to Darwin about the American reprint, etc., and spoke of
the work itself in somewhat greater detail:--

      “The _best part_, I think, is the _whole_, _i.e._ its _plan_
      and _treatment_, the vast amount of facts and acute inferences
      handled as if you had a perfect mastery of them.... Then your
      candour is worth everything to your cause. It is refreshing to
      find a person with a new theory who frankly confesses that he
      finds difficulties.... The moment I understood your premisses,
      I felt sure you had a real foundation to hold on.... I am free
      to say that I never learnt so much from one book as I have from
      yours.”

He considered that the attempt to account for the formation of organs
such as eyes by natural selection, was the weakest point in the book.
This view is to be explained by his strong teleological convictions.

Although Asa Gray was the great exponent of the “Origin” in America,
he could not agree with Darwin on one important point--viz. on the
exclusion of the ordinary conceptions of design in nature by the
principle of natural selection. He believed that the two conceptions
could be reconciled, and that design in some way worked in and through
natural selection. By design is here meant what Huxley called “the
commoner and coarser form of teleology,” and which he believed to be
now refuted--“the teleology which supposes that the eye, such as we see
it in man or one of the higher vertebrata, was made with the precise
structure it exhibits for the purpose of enabling the animal which
possesses it to see, has undoubtedly received its death-blow.” Huxley
goes on to point out that there is a “wider teleology, which ... is
actually based upon the fundamental proposition of evolution ... that
the whole world ... is the result of the mutual interaction, according
to definite laws, of the forces possessed by the molecules of which
the primitive nebulosity of the universe was composed.” Therefore,
“a sufficient intelligence could, from a knowledge of the properties
of the molecules of that vapour, have predicted, say, the state of
the fauna of Britain in 1869, with as much certainty as one can say
what will happen to the vapour of the breath on a cold winter’s day.”
(“Genealogy of Animals,” _The Academy_, 1869, reprinted in “Critiques
and Addresses,” and quoted in his chapter “On the Reception of the
‘Origin of Species’” in the “Life and Letters,” Vol. II.)

But at the time of the appearance of the “Origin,” many who sympathised
with the general drift of the argument were not yet prepared for
the “wider teleology.” Of these Asa Gray may be taken as the
representative; and it will be of interest to follow the controversy
between him and Darwin as regards design and natural selection. The
recently published “Letters of Asa Gray to Charles Darwin” (Macmillan)
enable us to follow the correspondence from the side of the great
American evolutionist.

Writing November 26th, 1860, Darwin refers to one of Asa Gray’s
articles on the “Origin”:--

      “I grieve to say that I cannot honestly go as far as you do
      about Design. I am conscious that I am in an utterly hopeless
      muddle. I cannot think that the world, as we see it, is the
      result of chance; and yet I cannot look at each separate thing
      as the result of Design. To take a crucial example, you lead me
      to infer--that you believe ‘that variation has been led along
      certain beneficial lines.’ I cannot believe this; and I think
      you would have to believe, that the tail of the Fantail was led
      to vary in the number and direction of its feathers in order to
      gratify the caprice of a few men. Yet if the Fantail had been a
      wild bird, and had used its abnormal tail for some special end,
      as to sail before the wind, unlike other birds, everyone would
      have said, ‘What a beautiful and designed adaptation.’ Again, I
      say I am, and shall ever remain, in a hopeless muddle.”

Elsewhere Darwin suggested that the pouter pigeon, if it occurred
wild, and used its inflated crop as a float, would be considered as a
striking example of design.

This controversy between them continued for many years. We find Asa
Gray referring to the argument of the pigeons three years later. Thus
he wrote (September 1st, 1863):--

      “I will consider about fantastic variation of pigeons. I see afar
      trouble enough ahead quoad design in nature, but have managed to
      keep off the chilliness by giving the knotty questions a rather
      wide berth. If I rather avoid, I cannot ignore the difficulties
      ahead. But if I adopt your view boldly, can you promise me any
      less difficulties?”

Writing the concluding paragraphs of the “Variations of Animals
and Plants under Domestication,” Darwin evidently bore in mind his
controversies on the subject with Asa Gray and Lyell, and the attacks
of the Duke of Argyll and others. Sending advanced sheets to Asa Gray,
he wrote on October 16th, 1867:--

      “I finish my book with a semi-theological paragraph, in which I
      quote and differ from you; what you will think of it, I know not.”

In relation to this interesting controversy, I think it well to quote,
almost in full, the metaphor by which Darwin enforced his argument that
the origin of species by natural selection precluded a belief in design
in nature as it was ordinarily conceived at the time.

This metaphor forms an important part of the conclusion of the work in
question (“Variation of Animals and Plants,” etc.):

      “The long-continued accumulation of beneficial variations will
      infallibly have led to structures as diversified, as beautifully
      adapted for various purposes and as excellently co-ordinated, as
      we see in the animals and plants around us. Hence I have spoken
      of selection as the paramount power, whether applied by man to
      the formation of domestic breeds, or by nature to the production
      of species. I may recur to the metaphor given in a former
      chapter: if an architect were to rear a noble and commodious
      edifice, without the use of cut stone, by selecting from the
      fragments at the base of a precipice wedged-formed stones for his
      arches, elongated stones for his lintels, and flat stones for his
      roof, we should admire his skill and regard him as the paramount
      power. Now, the fragments of stone, though indispensable to the
      architect, bear to the edifice built by him the same relation
      which the fluctuating variations of organic beings bear to the
      varied and admirable structures ultimately acquired by their
      modified descendants.

      “Some authors have declared that natural selection explains
      nothing, unless the precise cause of each slight individual
      difference be made clear. If it were explained to a savage
      utterly ignorant of the art of building, how the edifice had been
      raised stone upon stone, and why wedge-formed fragments were used
      for the arches, flat stones for the roof, &c.; and if the use of
      each part and of the whole building were pointed out, it would
      be unreasonable if he declared that nothing had been made clear
      to him, because the precise cause of the shape of each fragment
      could not be told. But this is a nearly parallel case with the
      objection that selection explains nothing, because we know not
      the cause of each individual difference in the structure of each
      being.”

       *       *       *       *       *

      “The shape of the fragments of stone at the base of our precipice
      may be called accidental, but this is not strictly correct; for
      the shape of each depends on a long sequence of events, all
      obeying natural laws.... But in regard to the use to which the
      fragments may be put, their shape may be strictly said to be
      accidental....”

In his article in the _Nation_ (March 19th, 1868), Asa Gray criticised
the metaphor as follows:--

      “But in Mr. Darwin’s parallel, to meet the case of nature
      according to his own view of it, not only the fragments of rock
      (answering to variation) should fall, but the edifice (answering
      to natural selection) should rise, irrespective of will or
      choice!”

This passage is quoted in the “Life and Letters” (Vol. III., p. 84),
and Francis Darwin makes the convincing reply:--

      “But my father’s parallel demands that natural selection shall be
      the architect, not the edifice--the question of design only comes
      in with regard to the form of the building materials.”

Darwin’s reply was contained in his letter to Asa Gray dated May 8th,
1868:--

      “You give a good slap at my concluding metaphor: undoubtedly I
      ought to have brought in and contrasted natural and artificial
      selection; but it seemed so obvious to me that natural selection
      depended on contingencies even more complex than those which
      must have determined the shape of each fragment at the base
      of my precipice. What I wanted to show was that, in reference
      to pre-ordainment, whatever holds good in the formation of an
      English pouter-pigeon holds good in the formation of a natural
      species of pigeon. I cannot see that this is false. If the right
      variations occurred, and no others, natural selection would be
      superfluous.”

To this, Asa Gray replied in his letter of May 25th:--

      “As to close of my article, to match close of your book,--you
      see plainly I was put on the defence by your reference to an
      old hazardous remark of mine. I found your stone-house argument
      unanswerable in substance (for the notion of design must after
      all rest mostly on faith, and on accumulation of adaptations,
      &c.); so all I could do was to find a vulnerable spot in the
      shaping of it, fire my little shot, and run away in the smoke.

      “Of course I understand your argument perfectly, and feel the
      might of it.”

From this last letter I think we may conclude that Asa Gray’s
feelings on this subject rested, as he says, “on faith,” and that,
intellectually, he saw no way of meeting Darwin’s arguments.




CHAPTER XVIII.

INFLUENCE OF DARWIN UPON HUXLEY.


[Sidenote: HUXLEY AND NATURAL SELECTION.]

It is of the utmost interest to trace the influence of Darwin upon
Huxley, his great General in the numerous controversial battles which
had to be fought before the new views were to secure a fair hearing
and, at length, complete success. Now that we are quietly enjoying the
fruit of his many victories, we are apt to forget how much we owe to
Huxley, not only for evolution, but for that perfect freedom in the
expression of thought and opinion which we enjoy. For Huxley fought
on wider issues than those raised by evolution, wide as these are;
and with a success so great that it is inconceivable that any new and
equally illuminating thought which the future may hold in store for
us, will meet with a reception like that accorded to the “Origin of
Species.”

At first sight it seems a simple matter to describe the effect of the
“Origin” upon Huxley, considering that he, more than any other man,
expounded it, and defended it from the most weighty of the attacks made
upon it. Hence, it is only natural to believe, as many have done, that
he was in entire agreement with the conclusions of the book as regards
natural selection as well as evolution. On the other hand, the opinion
has often been expressed that Huxley, although agreeing with the
“Origin” for some years after its first appearance, changed his mind in
later years, and no longer supported Darwin’s views.

I shall give reasons for rejecting both these opinions about Huxley,
although the first is far nearer the truth than the second. The
latter is clearly untenable, and was probably merely an inference
from the fact that after a time Huxley ceased to enter into Darwinian
controversies. But this was because he had done his work with entire
success, and therefore turned his attention in other directions.
Whenever he was called on to write or speak about Darwinism, as he was
on two occasions within a few months of his death, his writings and
speeches left no doubt about his thoughts on the subject. Furthermore,
in the Preface to “Darwiniana,” written in 1893, he expressly denied
that he had recanted or changed his opinions about Darwin’s views.

In order to appreciate the influence of Darwin upon Huxley, we must
find out the beliefs of the latter upon the “species question” before
the appearance of the “Origin.” In his chapter “On the Reception of
the ‘Origin of Species’” (“Life and Letters,” Vol. II.) Huxley says
that, before 1858, he took up an agnostic position as regards evolution
“... upon two grounds: firstly, that up to that time, the evidence in
favour of transmutation was wholly insufficient; and, secondly, that no
suggestion respecting the causes of the transmutation assumed, which
had been made, was in any way adequate to explain the phenomena.” It
is obvious that these two grounds are entirely distinct, and that the
logical foundation of the first is far more secure than that of the
second.

The effect of the “Origin” was completely to convince Huxley on the
first ground: from that time he never doubted the truth of evolution,
however it may have been brought about. With regard to the second
ground, it is quite clear that Huxley had a very high opinion of
natural selection: he thought it incomparably the best suggestion upon
the subject that had ever been made, and he firmly believed that it
accounted for something--that it may even have taken a dominant part
in bringing about evolution. On the other hand, he never felt quite
confident about the entire sufficiency of the evidence in its favour.
It is probable that he was far more interested in the establishment
of evolution as a fact than in natural selection as an explanation of
it. He saw the vast amount of research in all kinds of new or almost
neglected lines, which would be directly inspired by evolution. And his
own investigations in some of these lines soon afforded some of the
most weighty evidence in favour of the doctrine. Natural selection had
not the same personal interest for him; no one has expounded it better
or defended it more vigorously and successfully, but Huxley’s own
researches never lay in directions which would have made them available
as a test of the theory. Of natural selection he might have used the
words of Mercutio--it may not be “so deep as a well, nor so wide as a
church door,” to contain the whole explanation of evolution, “but ’tis
enough ’twill serve”; it will, at any rate, prevent him from feeling
the second ground on which he had maintained an agnostic position.

I believe that he maintained these views with inflexible consistency
throughout his life, the only indications of change being in the last
year, when the contrast between his certainty of evolution and his
uncertainty of natural selection, as expressed in the two speeches
quoted on pp. 140, 141, was, perhaps, more sharply marked than at any
other period.

It is now proposed to support this conclusion by many extracts from
Huxley’s writings, as well as from his speeches, which have been
alluded to above. The deep interest of the subject, and the wide
differences of opinion with regard to it, justify, and indeed demand,
copious quotations selected from works and speeches, written and spoken
at many different times during the years between 1858 and 1894.

It may not be out of place to emphasise the fact that the sole
responsibility for the conclusions here drawn rests with the author of
this volume, and that the evidence on which the conclusions rest is
supplied in full.

About a month before the “Origin” was published, Darwin wrote to
Professor Huxley asking for the names of foreigners to whom to send his
book. This communication is of great interest as being the earliest
letter, accessible to the public, which he wrote to Huxley. In it he
says: “I shall be _intensely_ curious to hear what effect the book
produces on you”; but he evidently thought that Huxley would disagree
with much in it, and must have been surprised as well as gratified at
the way in which it was received. In his chapter “On the Reception of
the ‘Origin of Species’” (“Life and Letters,” Vol. II.), Huxley writes:
“My reflection, when I first made myself master of the central idea of
the ‘Origin,’ was, ‘How extremely stupid not to have thought of that.’”

Huxley replied on November 23rd, 1859--the day before the publication
of the “Origin”--saying that he had finished the book on the previous
day. His letter was a complete acceptance of evolution as apart from
any theory which may account for it; and a thorough agreement with
natural selection as a “true cause for the production of species.”
At no time in his life did he state how far he considered natural
selection to be a sufficient cause. He was only “prepared to go to the
stake, if requisite, in support of” the chapters which marshal the
evidence for evolution (ix., and most parts of x., xi., and xii.).

With regard to the earlier chapters, which propound the theory of
natural selection, his exact words are:--

      “As to the first four chapters, I agree thoroughly and fully
      with all the principles laid down in them. I think you have
      demonstrated a true cause for the production of species, and have
      thrown the _onus probandi_, that species did not arise in the way
      you suppose, on your adversaries.”

Darwin replied with much warmth, and expressed himself as “Now
contented and able to sing my _Nunc Dimittis_.”

In the _Times_ of December 26th, 1859, appeared a masterly article upon
the “Origin,” and, after a time, it became known that Huxley was its
author. Volume II. of the “Life and Letters” explains the circumstances
under which the review was written. The article is reprinted as the
first essay (“The Darwinian Hypothesis,” I.) in “Darwiniana” (Vol.
II. of the “Collected Essays of Professor Huxley,” London, 1893). The
following quotation (pp. 19, 20) shows the attitude he took up with
regard to natural selection:--

      “That this most ingenious hypothesis enables us to give a reason
      for many apparent anomalies in the distribution of living
      beings in time and space, and that it is not contradicted by
      the main phenomena of life and organisation appear to us to be
      unquestionable; and, so far, it must be admitted to have an
      immense advantage over any of its predecessors. But it is quite
      another matter to affirm absolutely either the truth or falsehood
      of Mr. Darwin’s views at the present stage of the enquiry. Goethe
      has an excellent aphorism defining that state of mind which he
      calls “Thätige Skepsis”--active doubt. It is doubt which so loves
      truth that it neither dares rest in doubting, nor extinguish
      itself by unjustified belief; and we commend this state of mind
      to students of species, with respect to Mr. Darwin’s or any other
      hypothesis as to their origin. The combined investigations of
      another twenty years may, perhaps, enable naturalists to say
      whether the modifying causes and the selective power, which Mr.
      Darwin has satisfactorily shewn to exist in Nature, are competent
      to produce all the effects he ascribes to them; or whether,
      on the other hand, he has been led to over-estimate the value
      of the principle of natural selection, as greatly as Lamarck
      over-estimated his _vera causa_ of modification by exercise.”

Of all the statements about natural selection made by Huxley, this one
seems to me the nearest to the spirit of the two speeches he made in
1894, in which it became evident that the intervening thirty-five years
had not brought the increased confidence he had hoped for. Furthermore,
in the Preface to “Darwiniana” (1893) he expressly stated that he had
not changed his mind as regards this article and the next which will be
considered (see p. 137, where the passage is quoted).

In 1860 Huxley wrote the article on “The Origin of Species” which
appeared in the _Westminster Review_ for April, and is reprinted in
“Darwiniana.” He here states the reasons for his doubts about natural
selection in considerable detail. At the beginning of the essay
(“Darwiniana,” p. 23) he asserts that--

      “... all competent naturalists and physiologists, whatever their
      opinions as to the ultimate fate of the doctrines put forth,
      acknowledge that the work in which they are embodied is a solid
      contribution to knowledge and inaugurates a new epoch in natural
      history.”

Towards the end of the essay, after vindicating the logical method
followed by Darwin, he continues (pp. 73–75):--

      “There is no fault to be found with Mr. Darwin’s method, then;
      but it is another question whether he has fulfilled all the
      conditions imposed by that method. Is it satisfactorily proved,
      in fact, that species may be originated by selection? that
      there is such a thing as natural selection? that none of the
      phœnomena exhibited by species are inconsistent with the origin
      of species in this way? If these questions can be answered
      in the affirmative, Mr. Darwin’s view steps out of the ranks
      of hypotheses into those of proved theories; but, so long as
      the evidence at present adduced falls short of enforcing that
      affirmation, so long, to our minds, must the new doctrine be
      content to remain among the former--an extremely valuable, and
      in the highest degree probable, doctrine, indeed the only extant
      hypothesis which is worth anything in a scientific point of view;
      but still a hypothesis, and not yet the theory of species.

      “After much consideration, and with assuredly no bias against Mr.
      Darwin’s views, it is our clear conviction that, as the evidence
      stands, it is not absolutely proven that a group of animals,
      having all the characters exhibited by species in Nature, has
      ever been originated by selection, whether artificial or natural.
      Groups having the morphological character of species, distinct
      and permanent races in fact, have been so produced over and
      over again; but there is no positive evidence, at present, that
      any group of animals has, by variation and selective breeding,
      given rise to another group which was even in the least degree
      infertile with the first. Mr. Darwin is perfectly aware of this
      weak point, and brings forward a multitude of ingenious and
      important arguments to diminish the force of the objection. We
      admit the value of these arguments to their fullest extent; nay,
      we will go so far as to express our belief that experiments,
      conducted by a skilful physiologist, would very probably obtain
      the desired production of mutually more or less infertile breeds
      from a common stock, in a comparatively few years; but still, as
      the case stands at present, this ‘little rift within the lute’ is
      not to be disguised nor overlooked.”

He concludes with a summary of the results of his argument. The
sentences which bear on the present question are as follows (pp. 77,
78):--

      “Our object has been attained if we have given an intelligible,
      however brief, account of the established facts connected with
      species, and of the relation of the explanation of those facts
      offered by Mr. Darwin to the theoretical views held by his
      predecessors and his contemporaries, and, above all, to the
      requirements of scientific logic. We have ventured to point
      out that it does not, as yet, satisfy all those requirements;
      but we do not hesitate to assert that it was superior to
      any preceding or contemporary hypothesis, in the extent of
      observational and experimental basis on which it rests, in its
      rigorously scientific method, and in its power of explaining
      biological phenomena, as was the hypothesis of Copernicus to the
      speculations of Ptolemy. But the planetary orbits turned out to
      be not quite circular after all, and, grand as was the service
      Copernicus rendered to science, Kepler and Newton had to come
      after him. What if the orbit of Darwinism should be a little
      too circular? what if species should offer residual phenomena,
      here and there, not explicable by natural selection? Twenty
      years hence naturalists may be in a position to say whether this
      is, or is not, the case; but in either event they will owe the
      author of ‘The Origin of Species’ an immense debt of gratitude.
      We should leave a very wrong impression on the reader’s mind if
      we permitted him to suppose that the value of that work depends
      wholly on the ultimate justification of the theoretical views
      which it contains. On the contrary, if they were disproved
      to-morrow, the book would still be the best of its kind--the
      most compendious statements of well-sifted facts bearing on the
      doctrine of species that has ever appeared.”

It is clear that two very distinct points are urged in this criticism
of natural selection--(1) the difficulty that selective methods
applied by man have not as yet produced all the characteristics of
true species; (2) supposing the latter difficulty to be surmounted or
sufficiently explained, the uncertainty as to how much or how little of
the process of evolution has been due to natural selection.

Later in the same year Darwin seems to have been a little disappointed
that Huxley’s confidence did not increase. Thus, he wrote on December
2nd, 1860:--

      “I entirely agree with you that the difficulties on my notions
      are terrific; yet having seen what all the _Reviews_ have said
      against me, I have far more confidence in the _general_ truth
      of the doctrine than I formerly had. Another thing gives me
      confidence--viz. that some who went half an inch with me now go
      further, and some who were bitterly opposed are now less bitterly
      opposed. And this makes me feel a little disappointed that you
      are not inclined to think the general view in some slight degree
      more probable than you did at first. This I consider rather
      ominous. Otherwise I should be more contented with your degree
      of belief. I can pretty plainly see that if my view is ever to
      be generally adopted, it will be by young men growing up and
      replacing the old workers, and then young ones finding that they
      can group facts and search out new lines of investigation better
      on the notion of descent than on that of creation.”

In 1863 Huxley delivered a course of lectures to working men on “The
Causes of the Phenomena of Organic Nature”; here, too, he expressed
his opinions about natural selection with great clearness and force.
These lectures are reprinted as the concluding part of “Darwiniana,”
and the references are to the pages of that volume of his collected
essays.

On page 464 we read--

      “Here are the phenomena of Hybridism staring you in the face, and
      you cannot say, ‘I can, by selective modification, produce these
      same results.’ Now, it is admitted on all hands, at present, so
      far as experiments have gone, it has not been found possible
      to produce this complete physiological divergence by selective
      breeding.... If we were shewn that this must be the necessary and
      inevitable results of all experiments, I hold that Mr. Darwin’s
      hypothesis would be utterly shattered.”

He then goes on to show that this is very far from proved, and
concludes (page 466)--

      “that though Mr. Darwin’s hypothesis does not completely
      extricate us from this difficulty at present, we have not the
      least right to say it will not do so.”

A passage on page 467 shows that Huxley placed natural selection
infinitely higher than any other attempt to account for evolution, and
indeed that he regarded all other attempts with scorn.

      “I really believe that the alternative is either Darwinism or
      nothing, for I do not know of any rational conception or theory
      of the Organic universe which has any scientific position at all
      beside Mr. Darwin’s.... Whatever may be the objections to his
      views, certainly all other theories are absolutely out of court.”

On page 468 he continues--

      “But you must recollect that when I say I think it is either Mr.
      Darwin’s hypothesis or nothing; that either we must take his
      view, or look upon the whole of organic nature as an enigma, the
      meaning of which is wholly hidden from us; you must understand
      that I mean that I accept it provisionally, in exactly the same
      way as I accept any other hypothesis.”

He concludes the lectures and the volume in which they are now
reproduced by the following eloquent testimony to the unique value of
the “Origin of Species”:--

      “I believe that if you strip it of its theoretical part it still
      remains one of the greatest encyclopædias of biological doctrine
      that any one man ever brought forth, and I believe that, if you
      take it as the embodiment of an hypothesis, it is destined to be
      the guide of biological and psychological speculation for the
      next three or four generations.”

The next essay from which I quote was written in 1871. At the beginning
of “Mr. Darwin’s Critics” (“Darwiniana,” p. 120) he uses words which,
if they stood alone, might be interpreted as an indication of a
stronger conviction.

      “Whatever may be thought or said about Mr. Darwin’s doctrines, or
      the manner in which he has propounded them, this much is certain,
      that, in a dozen years, the ‘Origin of Species’ has worked as
      complete a revolution in biological science as the ‘Principia’
      did in astronomy--and it has done so, because, in the words of
      Helmholtz, it contains an ‘essentially new creative thought.’”

This last quotation, and the following one, from “Evolution in
Biology,” written in 1878, are, I think, among the strongest
utterances in favour of natural selection to be found in the Collected
Essays. At the conclusion of the above-named essay (_l. c._, p. 223) he
states that it was clearly seen that--

      “if the explanation would apply to species, it would not
      only solve the problem of their evolution, but that it would
      account for the facts of teleology, as well as for those of
      morphology;...”

      “How far ‘natural selection’ suffices for the production of
      species remains to be seen. Few can doubt that, if not the whole
      cause, it is a very important factor in that operation; and that
      it must play a great part in the sorting out of varieties into
      those which are transitory and those which are permanent.”

The seventh essay, “The Coming of Age of ‘The Origin of Species,’” was
written in 1880. His complete confidence in evolution, as shown in this
essay, may be contrasted with his cautious statements about natural
selection. He boldly affirms evolution to be the fundamental doctrine
of the “Origin of Species,” while natural selection is, I believe,
neither mentioned nor even alluded to. On this great occasion he thus
emphasised the immense debt we owe to Darwin in that he was the first
to produce adequate evidence in favour of the ancient doctrine of
evolution, a benefit quite distinct from that which he conferred in the
theory of natural selection (see pp. 100–102).

The following are among the most confident statements about evolution
to be found in this essay. Speaking of the “Origin,” he says (p.
229):--

      “... the general doctrine of evolution, to one side of which it
      gives expression, obtains, in the phenomena of biology, a firm
      base of operations whence it may conduct its conquest of the
      whole realm of nature.”

And again, on page 332:--

      “The fundamental doctrine of the ‘Origin of Species,’ as of all
      forms of the theory of evolution applied to biology, is ‘that
      the innumerable species, genera, and families of organic beings
      with which the world is peopled have all descended, each within
      its own class or group, from common parents, and have all been
      modified in the course of descent.’”

Furthermore, on page 242 we read:--

      “I venture to repeat what I have said before, that so far as the
      animal world is concerned, evolution is no longer a speculation,
      but a statement of historical fact. It takes its place alongside
      of those accepted truths which must be reckoned with by
      philosophers of all schools.”

And on the same page he quotes with approval the statement by M.
Filhol of the results to which he had been led by his palæontological
investigations:--

      “Under the influence of natural conditions of which we have no
      exact knowledge, though traces of them are discoverable, species
      have been modified in a thousand ways: species have arisen which,
      becoming fixed, have thus produced a corresponding number of
      secondary species.”

Similarly, in the Obituary notice in _Nature_ (1882), Huxley speaks
of the secure position in which Darwin had placed the doctrine of
evolution as his great achievement. The following eloquent passage
occurs on page 247 of “Darwiniana”:--

      “None have fought better, and none have been more fortunate, than
      Charles Darwin. He found a great truth trodden underfoot, reviled
      by bigots, and ridiculed by all the world; he lived long enough
      to see it, chiefly by his own efforts, irrefragibly established
      in science,...”

In the impressive speech in which Huxley handed over the statue of
Darwin to the Prince of Wales, as representative of the Trustees of
the British Museum, on June 9th, 1885 (“Darwiniana,” p. 248), the
references to Darwin are most consistent with the view that the support
to evolution was held by the speaker to be the great work of his life.
Natural selection is not mentioned.

The next publication on this subject by Huxley is the celebrated
chapter “On the Reception of the ‘Origin of Species,’” in the second
volume of the great “Life and Letters.” In this chapter he speaks
rather more confidently about natural selection than in some of the
earlier essays and in the later speeches:--

      “The reality and the importance of the natural processes on which
      Darwin founds his deductions are no more doubted than those
      of growth and multiplication; and, whether the full potency
      attributed to them is admitted or not, no one doubts their vast
      and far-reaching significance.”

But of evolution he speaks far more strongly:--

      “To any one who studies the signs of the times, the emergence
      of the philosophy of Evolution, [“bound hand and foot and
      cast into utter darkness during the millennium of theological
      scholasticism”] in the attitude of claimant to the throne of the
      world of thought, from the limbo of hated and, as many hoped,
      forgotten things, is the most portentous event of the nineteenth
      century.”

And for this he gives Darwin the credit.

Later on he indicates the sense in which his keen appreciation of
natural selection is to be understood. Thus, such strong statements as--

      “... the publication of the Darwin and Wallace papers in 1858,
      and still more that of the ‘Origin’ in 1859, had the effect ...
      of the flash of light, which to a man who has lost himself in a
      dark night, suddenly reveals a road which, whether it takes him
      straight home or not, certainly goes his way”;

and--

      “The facts of variability, of the struggle for existence, of
      adaptation to conditions, were notorious enough; but none of
      us had suspected that the road to the heart of the species
      problem lay through them, until Darwin and Wallace dispelled
      the darkness, and the beacon-fire of the ‘Origin’ guided the
      benighted,”

if they stood alone, might naturally be interpreted as an unqualified
testimony to the permanent truth of natural selection. But this
interpretation is expressly excluded:--

      “Whether the particular shape which the doctrine of evolution, as
      applied to the organic world, took in Darwin’s hands, would prove
      to be final or not, was, to me, a matter of indifference. In my
      earliest criticisms of the ‘Origin’ I ventured to point that its
      logical foundation was insecure ...; and that insecurity remains.”

Its value for Huxley was that it was “incomparably more probable than
the creation hypothesis”; that it was “a hypothesis respecting the
origin of known organic forms, which assumed the operation of no causes
but such as could be proved to be actually at work”; that it provided
“clear and definite conceptions which could be brought face to face
with facts and have their validity tested”; that it freed us “for ever
from the dilemma--refuse to accept the creation hypothesis, and what
have you to propose that can be accepted by any cautious reasoner?”
Indeed, the hypothesis did away with this dilemma, even if it were
itself to disappear; for “if we had none of us been able to discern
the paramount significance of some of the most patent and notorious of
natural facts, until they were, so to speak, thrust under our noses,
what force remained in the dilemma--creation or nothing? It was obvious
that, hereafter, the probability would be immensely greater, that
the links of natural causation were hidden from our purblind eyes,
than that natural causation should be incompetent to produce all the
phenomena of nature.”

Therefore, “the only rational course for those who had no other object
than the attainment of truth, was to accept ‘Darwinism’ as a working
hypothesis, and see what could be made of it.” Furthermore, “Whatever
may be the ultimate fate of the particular theory put forth by Darwin,
... all the ingenuity and all the learning of hostile critics has not
enabled them to adduce a solitary fact, of which it can be said, this
is irreconcilable with the Darwinian theory.”

Taking this argument as a whole, it seems to me to amount to the words
of Mercutio quoted at the beginning of this chapter.

In the following year (1888) Huxley wrote the Obituary Notice of
Darwin for the Proceedings of the Royal Society: it is reprinted in
“Darwiniana” (pp. 253 _et seq._). In this admirable essay the author
recognises that Darwin evidently accepted evolution before he could
offer any explanation of the motive cause by which that process
took place. The theory of descent with modification had often been
thought of before, “but in the eyes of the naturalist of the ‘Beagle’
(and, probably, in those of most sober thinkers), the advocates of
transmutation had done the doctrine they expounded more harm than
good.” Huxley speaks of the “Origin” as “one of the hardest books to
master,” in this agreeing with Hooker (see p. 111).

In this essay Huxley gives a clear and excellent statement of natural
selection, prefaced by these words (p. 287):--

      “Although, then, the present occasion is not suitable for any
      detailed criticism of the theory, or of the objections which have
      been brought against it, it may not be out of place to endeavour
      to separate the substance of the theory from its accidents; and
      to shew that a variety not only of hostile comments, but of
      friendly would-be improvements, lose their _raison d’être_ to the
      careful student.”

Then follows a brief but epigrammatic description, such as only Huxley
could have written, of the theory, and some of the chief arguments
which have revolved round it. Occasionally he speaks as if he were
stating his own opinion as well as Darwin’s, but throughout it seems
to me that his object is not to give his own views but to write a fair
and clear account of Darwin’s theory, and to defend it from a number
of criticisms and modifications which have been, from time to time,
brought forward.

“Darwiniana” was published in 1893, and this is the date of the
Preface, in which Huxley speaks of--

      “... the ancient doctrine of Evolution, rehabilitated and placed
      upon a sound scientific foundation, since, and in consequence of,
      the publication of the ‘Origin of Species....’”

He thinks that readers will admit that in the first two essays (see
pages 124–128 of the present volume)--

      “... my zeal to secure fair play for Mr. Darwin, did not drive
      me into the position of a mere advocate; and that, while doing
      justice to the greatness of the argument, I did not fail to
      indicate its weak points. I have never seen any reason for
      departing from the position which I took up in these two essays;
      and the assertion which I sometimes meet with nowadays, that I
      have ‘recanted’ or changed my opinions about Mr. Darwin’s views,
      is quite unintelligible to me.”

      “As I have said in the seventh essay, [see pages 131, 132 of the
      present volume] the fact of evolution is to my mind sufficiently
      evidenced by palæontology; and I remain of the opinion expressed
      in the second, that until selective breeding is definitely proved
      to give rise to varieties infertile with one another, the logical
      foundation of the theory of natural selection is incomplete.”

It is therefore clear, as I have before stated, that Huxley, in 1893,
re-stated his criticisms and qualifications of thirty years before,
and expressed his conviction anew of the validity of the objections
which he then raised against a full and complete acceptance of natural
selection.

We now come to the last and most significant of all Huxley’s utterances
on evolution and natural selection, made on two great occasions in the
last year of his life. Lord Salisbury, in his eloquent and interesting
Presidential Address to the British Association at Oxford (August 8th,
1894), had said of Darwin:--

      “He has, as a matter of fact, disposed of the doctrine of the
      immutability of species.... Few now are found to doubt that
      animals separated by differences far exceeding those that
      distinguish what we know as species have yet descended from
      common ancestors.”

While thus completely admitting evolution in the organic world, Lord
Salisbury attacked natural selection on two grounds--first, on the
insufficiency of the time allowed by physicists for a process which
is, of necessity, extremely slow in its operation; secondly, on the
ground that “we cannot demonstrate the process of natural selection in
detail; we cannot even, with more or less ease, imagine it.” And his
main objection under this head was the supposed difficulty in securing
the union of successful variations. The actual words have been already
quoted on page 83, where it was shown that the criticism does not apply
to natural selection, but to a theory mistaken by the speaker for that
of Darwin. Curiously enough, the first objection of the insufficiency
of time was the indirect cause of a subsequent trenchant criticism by
Professor Perry of the line of mathematical reasoning on which the
limit had been fixed.

Huxley was called on to second the vote of thanks, and his speech had
evidently been considered with the greatest care. I quote the passages
which bear on evolution and natural selection from the _Times_ of
August 9th, 1894, in which a _verbatim_ report is furnished:--

      “... As one of those persons who for many years past had made
      a pretty free use of the comfortable word ‘evolution,’ let him
      remind them that 34 years ago a considerable discussion, to which
      the President had referred, took place in one of their sectional
      meetings upon what people frequently called the ‘Darwinism
      question,’ but which on that occasion was not the Darwinism
      question, but the very much deeper question which lay beneath
      the Darwinism question--he meant the question of evolution....
      The two doctrines, the two main points, for which these men
      [Sir John Lubbock, Sir J. Hooker, and the speaker] fought were
      that species were mutable, and that the great variety of animal
      forms had proceeded from gradual and natural modification of the
      comparatively few primitive forms....”

After alluding to the revolution in thought which had taken place in
thirty-four years, he said:--

      “As he noted in the presidential address to which they had just
      listened with such well-deserved interest, he found it stated on
      that which was then and at this time the highest authority for
      them, that as a matter of fact the doctrine of the immutability
      of species was disposed of and gone. He found that few were
      now found to doubt that animals separated by differences far
      exceeding those which they knew as species were yet descended
      from a common ancestry. Those were their propositions; those
      were the fundamental principles of the doctrine of evolution.
      Darwinism was not evolution, nor Spencerism, nor Hæckelism, nor
      Weismannism, but all these were built on the fundamental doctrine
      which was evolution, which they maintained so many years, and
      which was that upon which their President had put the seal of his
      authority that evening....”

Huxley thus hailed the statements of the President in favour of
evolution, while the attacks on natural selection he merely met by
saying that the address would have made a good subject for discussion
in one of the sections, and by insisting with impressive solemnity that
evolution was a very different thing from natural selection, thereby
implying that the former would be unaffected by the fate of the latter.

The second occasion was between three and four months later, when
Huxley spoke at the Anniversary Dinner of the Royal Society, November
30th, 1894, after having been awarded the Darwin Medal at the afternoon
meeting. I quote his words from the _verbatim_ report of the _Times_
for December 1st:--

      “... I am as much convinced now as I was 34 years ago that
      the theory propounded by Mr. Darwin, I mean that which he
      propounded--not that which has been reported to be his by too
      many ill-instructed, both friends and foes--has never yet been
      shewn to be inconsistent with any positive observations, and if
      I may use a phrase which I know has been objected to and which
      I use in a totally different sense from that in which it was
      first proposed by its first propounder, I do believe that on
      all grounds of pure science it ‘holds the field,’ as the only
      hypothesis at present before us which has a sound scientific
      foundation.... I am sincerely of opinion that the views which
      were propounded by Mr. Darwin 34 years ago may be understood
      hereafter as constituting an epoch in the intellectual history of
      the human race. They will modify the whole system of our thought
      and opinion, our most intimate convictions. But I do not know, I
      do not think anybody knows, whether the particular views which he
      held will be hereafter fortified by the experience of the ages
      which come after us; ... whether the particular form in which
      he has put them before us (the Darwinian doctrines) may be such
      as is finally destined to survive or not is more, I venture to
      think, than anybody is capable at this present moment of saying.”

It is unnecessary to say anything about this passage, which fitly sums
up and sets the seal on the long series of quotations I have felt
obliged to make.

It may not be out of place, however, to state in a few words why
many naturalists, including the present writer, are not inclined to
accept the extremely cautious and guarded language of one upon whom,
with regard to so many other subjects, they have ever looked as their
teacher and guide. Concerning the verification of a hypothesis, Huxley
said in his lectures to working men (“Darwiniana,” pages 367, 368)--

      “... that the more extensive verifications are,--that the more
      frequently experiments have been made, and results of the same
      kind arrived at,--that the more varied the conditions under which
      the same results are attained, the more certain is the ultimate
      conclusion....”

And again--

      “In scientific enquiry it becomes a matter of duty to expose a
      supposed law to every possible kind of verification, and to take
      care, moreover, that this is done intentionally, and not left to
      a mere accident....”

It may well be that the length of time required before an
artificially-selected race will exhibit, when interbred with the parent
species, phenomena of hybridism similar to those which are witnessed
when distinct natural species are interbred--will be fatal to the
production of this important line of evidence. But there is nothing to
hinder us from holding the reasonable belief that such evidence might
be obtained if we had command of the necessary conditions; and in the
meantime other evidence of the most satisfactory kind is accumulating,
and on a vast scale. Whenever a naturalist approaches a problem in the
light of the theory of natural selection, and is able, by its aid,
to predict a conclusion which subsequent investigation proves to be
correct, he is helping in the production of evidence in favour of the
theory. When a naturalist has found the formula “if natural selection
be true so-and-so ought to happen” the safest of all guides into
the unknown, when it has brought him success many times and in very
different directions, when he knows that many other workers in other
fields of biological inquiry have had a similarly happy experience, he
gradually comes to feel a profound confidence in the permanent truth
and the far-reaching importance of the great theory which has served
him so well.




CHAPTER XIX.

THE DIFFICULTY WITH WHICH THE “ORIGIN” WAS UNDERSTOOD.


Even earlier than Huxley, H. C. Watson wrote warmly accepting natural
selection. In his letter, which is dated November 21st, 1859, he said:--

      “Your leading idea will surely become recognised as an
      established truth in science--_i.e._ ‘Natural Selection.’ It has
      the characteristics of all great natural truths, clarifying what
      was obscure, simplifying what was intricate, adding greatly to
      previous knowledge. You are the greatest revolutionist in natural
      history of this century, if not of all centuries.”

[Sidenote: MISUNDERSTANDING OF THE THEORY.]

For some years to come, however, such views as these were the
exception, as will soon be shown.

The Duke of Argyll has argued (_Nineteenth Century_, December,
1887) that the success of “Natural Selection” has followed from the
convincing character of the words used, scientific men (“the populace
of science” he calls them) being so easily led by the power of loose
analogies that they have been convinced of the truth of the principle
because they are familiar with Nature on the one hand, and selection as
a process on the other!

As I am not aware that this preposterous suggestion has ever been
publicly disproved, and since therefore some readers of the journal in
question may have been misled by it, I have collected much evidence,
which proves that the principle of natural selection was only absorbed
with the very greatest difficulty, and that the words used in
describing it for a long time entirely failed to inform even eminent
scientific men of the essential characteristics of the theory itself,
and certainly failed most signally to convince them. Conviction came
very gradually as the theory was slowly understood and was seen to
offer an intelligible explanation of an immense and ever-increasing
number of facts.

I will now bring together quotations from Darwin’s letters in 1859 and
1860, showing how soon he came to realise the difficulty with which
natural selection was understood, and to feel that he might have been
more successful with some other title.

In 1859 he wrote to Dr. W. B. Carpenter--“I have found the most
extraordinary difficulty in making even able men understand at what
I was driving.” The remaining quotations are all taken from letters
written in 1860. By the middle of this year, when he was feeling
oppressed by hostile reviews and unfair and ignorant criticisms (“I
am getting wearied at the storm of hostile reviews, and hardly any
useful”), he often alludes to the failure of opponents to understand
his theory. Thus, in a letter to Hooker (June 5th), he says:--

      “This review, however, and Harvey’s letter have convinced me that
      I must be a very bad explainer. Neither really understand what
      I mean by Natural Selection.... I hope to God you will be more
      successful than I have been in making people understand your
      meaning.”

He says almost the same thing in a letter to Lyell (June 6th):--

      “... I am beginning to despair of ever making the majority
      understand my notions.... I must be a very bad explainer. I
      hope to Heaven that you will succeed better. Several reviews
      and several letters have shown me too clearly how little I am
      understood. I suppose ‘Natural Selection’ was a bad term; ...
      I can only hope by reiterated explanations finally to make the
      matter clearer.”

Writing to Asa Gray, he says:--

      “... I have had a letter of fourteen folio pages from Harvey
      against my book, with some ingenious and new remarks; but it is
      an extraordinary fact that he does not understand at all what I
      mean by Natural Selection.”

Later on, he again wrote to Lyell:--

      “Talking of ‘natural selection’; if I had to commence _de novo_,
      I would have used ‘natural preservation.’ For I find men like
      Harvey of Dublin cannot understand me, though he has read the
      book twice. Dr. Gray of the British Museum remarked to me that,
      ‘_selection_ was obviously impossible with plants! No one could
      tell him how it could be possible!’ And he may now add that the
      author did not attempt it to him!”

And still later he wrote asking Lyell’s advice as to additions to a
new edition of the “Origin,” saying:--“I would also put a note to
‘Natural Selection,’ and show how variously it has been misunderstood.”
This note is to be found on page 63 of the sixth edition. In it he
tells us that some writers have “even imagined that natural selection
induces variability,” instead of merely preserving it; others that
natural selection “implies conscious choice in the animals which become
modified”; others that it is set up “as an active power or Deity.”
In writing (December) to Murray about a new edition of the “Origin,”
he alludes to the “many corrections, or rather additions, which I
have made in hopes of making my many rather stupid reviewers at least
understand what is meant.”

He seems to have retained a very vivid recollection of the difficulty
with which his theory was understood at first; thus he tells us in his
“Autobiography”:--

      “I tried once or twice to explain to able men what I meant by
      Natural Selection, but signally failed.”

Why the term “natural selection” was chosen by Darwin is very clearly
shown in the three following quotations from letters to distinguished
scientific men, which were probably written in answer to attacks or
criticisms on this very point.

He writes to Lyell in 1859, “Why I like the term is that it is
constantly used in all works on breeding.”

Writing to H. G. Bronn in 1860, he explains his motives with great
clearness and force:--

      “Several scientific men have thought the term ‘Natural Selection’
      good, because its meaning is _not_ obvious, and each man could
      not put on it his own interpretation, and because it at once
      connects variation under domestication and nature.... Man has
      altered, and thus improved the English race-horse by _selecting_
      successive fleeter individuals; and I believe, owing to the
      struggle for existence, that similar _slight_ variations in a
      wild horse, _if advantageous to it_, would be _selected_ or
      _preserved_ by nature; hence Natural Selection.”

In 1866 he wrote to Wallace, comparing the term with that which we owe
to Herbert Spencer:--

      “I fully agree with all that you say on the advantages of H.
      Spencer’s excellent expression of ‘the survival of the fittest.’
      This however had not occurred to me till reading your letter. It
      is, however, a great objection to this term that it cannot be
      used as a substantive governing a verb; and that it is a real
      objection I infer from H. Spencer continually using the words,
      natural selection. I formerly thought, probably in an exaggerated
      degree, that it was a great advantage to bring into connection
      natural and artificial selection; this indeed led me to use a
      term in common, and I still think it some advantage.... The term
      Natural Selection has now been so largely used abroad and at
      home, that I doubt whether it could be given up, and with all its
      faults I should be sorry to see the attempt made. Whether it will
      be rejected must now depend ‘on the survival of the fittest.’ As
      in time the term must grow intelligible the objections to its use
      will grow weaker and weaker. I doubt whether the use of any term
      would have made the subject intelligible to some minds, clear
      as it is to others; for do we not see even to the present day
      Malthus on Population absurdly misunderstood? This reflection
      about Malthus has often comforted me when I have been vexed at
      the mis-statement of my own views.”

A large number of critics not only failed to understand natural
selection, but they asserted that it was precisely the same theory as
that advanced by Lamarck or one of the other writers on evolution
before Darwin. This seems almost incredible to us at the present
day, when the biological world is divided into two sections on the
very subject, and when it is generally recognised that Lamarck’s
theory would be, if it were proved to be sound, a formidable rival to
natural selection as a motive cause of evolution. But the following
quotations--a few among many--leave no doubt whatever upon the subject.

Evidence on this point reached Darwin almost immediately after the
appearance of the “Origin.” Thus he writes to Hooker on December 14th,
1859:--

      “Old J. E. Gray, at the British Museum, attacked me in fine
      style: ‘You have just reproduced Lamarck’s doctrine, and nothing
      else, and here Lyell and others have been attacking him for
      twenty years, and because _you_ ... say the very same thing, they
      are all coming round; it is the most ridiculous inconsistency,’
      &c. &c.”

In the following year, Wilberforce, Bishop of Oxford, writing in the
_Quarterly Review_ for July, 1860, appeals to Lyell,

      “in order that with his help this flimsy speculation may be as
      completely put down as was what in spite of all denials we must
      venture to call its twin though less-instructed brother, the
      ‘Vestiges of Creation.’”

Again, Dr. Bree, in “Species not Transmutable,” says:

      “The only real difference between Mr. Darwin and his two
      predecessors, [Lamarck and the “Vestiges”] is this:--that while
      the latter have each given a mode by which they conceive the
      great changes they believe in have been brought about, Mr. Darwin
      does no such thing.”

One of the most interesting of the countless examples of
misunderstanding is contained in a recently published letter from W. S.
Macleay to Robert Lowe.[H] This letter was written from Elizabeth Bay,
and is dated May, 1860, evidently just after the first edition of the
“Origin,” a copy of which had been sent by Robert Lowe, had been read
by Macleay.

      “Again if this primordial cell had a Creator, as Darwin seems
      to admit, I do not see what we gain by denying the Creator, as
      Darwin does, all management of it after its creation. Lamarck
      was more logical in supposing it to have existed of itself from
      all eternity--indeed this is the principal difference that I
      see between this theory of Darwin’s and that of Lamarck, who
      propounded everything essential in the former theory, in a work
      now rather rare--his ‘Philosophie Zoologique.’ But you may see
      an abridgment of it in so common a book as his ‘Histoire Nat.
      des Animaux Vertébrés,’ vol. i., pp. 188, _et seq._--Edit. 1818,
      where the examples given of natural selection are the gasteropod
      molluscs.... Natural selection (sometimes called ‘struggles’ by
      Darwin) is identical with the ‘Besoins des Choses’ of Lamarck,
      who, by means of his hypothesis, for instance, assigns the
      constant stretching of the neck to reach the acacia leaves as
      the cause of the extreme length of it in the giraffe; much in
      the same way the black bear, according to Darwin, became a
      whale, which I believe as little as his other assertion that our
      progenitors anciently had gills--only they had dropped off by
      want of use in the course of myriads of generations.”

I had long been anxious to possess a copy of the first edition of the
“Origin,” and was fortunate enough to come across one about the time
when Macleay’s letter was pointed out to me by my wife. I opened the
title-page, and found upon it the signature “W. S. Macleay”; it must
have been the very volume given him by Robert Lowe, which Macleay had
read and believed he had been fairly criticising. Out of Macleay’s
volume, therefore, I quote the sentences he referred to in his letter.

Darwin’s real statement about the black bear which “became a whale” is
to be found on page 184:--

      “In North America the black bear was seen by Hearne swimming
      for hours with widely open mouth, thus catching, like a whale,
      insects in the water. Even in so extreme a case as this, if
      the supply of insects were constant, and if better adapted
      competitors did not already exist in the country, I can see
      no difficulty in a race of bears being rendered, by natural
      selection, more and more aquatic in their structure and habits,
      with larger and larger mouths, till a creature was produced as
      monstrous as a whale.”

The statement about the gills which “dropped off by want of use”
becomes in the original (p. 191):--

      “In the higher vertebrata the branchiæ have wholly
      disappeared--the slits on the sides of the neck and the loop-like
      course of the arteries still marking in the embryo their former
      position.”

Although the hypothetical case of the black bear--carefully guarded as
it is--does not now appear to us at all extravagant (indeed, in the
cleft cheeks of the goat-sucker we have a precisely analogous case),
Darwin seems to have thought it unsuitable, probably because it became
an easy butt for ignorant ridicule. We find accordingly that in the
second and all subsequent editions everything after the word “water”
is omitted, while “almost” is inserted before “like a whale.” He was
alluding to this passage when he wrote to Lyell (December 22nd, 1859):
“Thanks about ‘Bears,’ a word of ill-omen to me.” Furthermore, Andrew
Murray[I] says, concerning the sentences as they stand in the first
edition:--

      “In quoting this, I do not at all mean to give it as a fair
      illustration of Mr. Darwin’s views. I only refer to it as
      indicating the extent to which he is prepared to go. The example
      here given I look upon (as I have reason to know that Mr. Darwin
      himself does) merely as an extreme and somewhat extravagant
      illustration, imagined expressly to show in a forcible way how
      ‘natural selection’ would operate in making a mouth bigger and
      bigger, because more advantageous.”




CHAPTER XX.

THE DIFFICULTY WITH WHICH THE “ORIGIN” WAS UNDERSTOOD
(_continued_)--VIEWS ON SPONTANEOUS GENERATION.


The history of opinion on evolution and natural selection, in the years
which followed the publication of the “Origin,” can be traced in the
titles of the papers and subjects of discussion at successive meetings
of the British Association. In the Presidential Address delivered by
Professor Newton to the Biological Section of the Manchester meeting in
1887, there is a most interesting account of the struggles which took
place:--

      “The ever-memorable meeting ... at Oxford in the summer of 1860
      saw the first open conflict between the professors of the new
      faith and the adherents of the old one. Far be it from me to
      blame those among the latter who honestly stuck to the creed in
      which they had educated themselves; but my admiration is for the
      few dauntless men who, without flinching from the unpopularity
      of their cause, flung themselves in the way of obloquy, and
      impetuously assaulted the ancient citadel in which the sanctity
      of ‘species’ was enshrined and worshipped as a palladium. However
      strongly I myself sympathised with them, I cannot fairly state
      that the conflict on this occasion was otherwise than a drawn
      battle; and thus matters stood when in the following year the
      Association met in this city [Manchester]. That, as I have
      already said, was a time of ‘slack water.’ But though the ancient
      beliefs were not much troubled, it was for the last time that
      they could be said to prevail; and thus I look upon our meeting
      in Manchester 1861 as a crisis in the history of biology. All
      the same, the ancient beliefs were not allowed to pass wholly
      unchallenged; and one thing is especially to be marked--they
      were challenged by one who was no naturalist at all, by one who
      was a severe thinker no less than an active worker; one who was
      generally right in his logic, and never wrong in his instinct;
      one who, though a politician, was invariably an honest man--I
      mean the late Professor Fawcett. On this occasion he brought the
      clearness of his mental vision to bear upon Mr. Darwin’s theory,
      with the result that Mr. Darwin’s method of investigation was
      shewn to be strictly in accordance with the rules of deductive
      philosophy, and to throw light where all was dark before.”

Professor Newton specially alluded to this interesting case of
Professor Fawcett as illustrating his conviction that the theory of
natural selection--

      “did not, except in one small point, require a naturalist to
      think it out and establish its truth.... But in order to see the
      effect of this principle upon organic life the knowledge--the
      peculiar knowledge--of the naturalist was required. This was
      the knowledge of those slight variations which are found in
      all groups of animals and plants.... Herein lay the triumph
      of Mr. Darwin and Mr. Wallace. That triumph, however, was not
      celebrated at Manchester. The question was of such magnitude as
      to need another year’s incubation, and the crucial struggle came
      a twelvemonth later when the Association met at Cambridge. The
      victory of the new doctrine was then declared in a way that none
      could doubt. I have no inclination to join in the pursuit of the
      fugitives.”

There is reason to believe that Professor Newton’s impressions of the
result of the celebrated meeting of the British Association at Oxford
in 1860 are more accurate than those of the eyewitness quoted in the
“Life and Letters.” The latter has pictured a brilliant triumph for
Huxley in the renowned duel with the Bishop of Oxford. But I have
been told by more than one of the audience that Huxley was really too
angry to speak effectively, nor is this to be wondered at, considering
the extreme provocation. Mr. William Sidgwick, who was present and
sympathised warmly with Huxley, has told me that this was his opinion.
I have heard the same from the Rev. W. Tuckwell, who also quoted a
remark of the late Professor Rolleston tending in the same direction.
Mr. Tuckwell said that it was clear that the audience as a whole
was not carried away by Huxley’s speech, but, on the contrary, was
obviously shocked at it; and he contrasted that occasion with another
at which he was also present, in the North, several years later,
when Huxley replied to an opponent who, like the bishop, appealed to
the theological prejudices of his hearers. But by that time the new
teachings had been absorbed, and Huxley gained a signal triumph.

[Sidenote: OPPOSITION.]

It must not be supposed that Darwin was by any means indifferent to the
attacks on his views. On the contrary, his sensitive nature was greatly
depressed by the violent and often most unfair criticisms to which he
was subjected, although beneath this evident disturbance lay the firm
conviction that he had seen the truth, and that the truth would in the
end be seen by others.

After the great fight with the bishop at the British Association at
Oxford, he wrote to Hooker (July 2nd, 1860):--

      “I have read lately so many hostile views, that I was beginning
      to think that perhaps I was wholly in the wrong, and that ----
      was right when he said the whole subject would be forgotten in
      ten years; but now that I hear that you and Huxley will fight
      publicly (which I am sure I never could do), I fully believe that
      our cause will, in the long-run, prevail.”

Looking at the history of opinion on this subject, the slowness with
which the new ideas were absorbed appears remarkable. Even so able a
man as the late Professor Rolleston wrote in 1870 (“Forms of Animal
Life,” Introduction, p. xxv., First Edition) the following carefully
guarded sentences, which, it is to be noted, deal with evolution rather
than natural selection. Speaking of “the theory of evolution with which
Mr. Darwin’s name is connected,” Rolleston says:--

      “Many of the peculiarities which attach to biological
      classifications would thus receive a reasonable explanation; but
      where verification is, _ex hypothesi_, impossible, such a theory
      cannot be held to be advanced out of the region of probability.
      The acceptance or rejection of the general theory will depend, as
      does the acceptance or rejection of other views supported merely
      by probable evidence, upon the particular constitution of each
      individual mind to which it is presented!”

It was too much to expect that many of the older scientific men would
retain sufficient intellectual flexibility to be able to recognise, as
Lyell had, that the facts of nature were explained and predicted better
by the new views than by those in which they had grown up. Darwin
thoroughly understood this, and, writing to his friends, maintained
that the fate of his views was in the hands of the younger men.

A grand yet simple conception like that of natural selection,
explaining and connecting together innumerable facts which people had
previously explained differently, or had become accustomed to regard as
inexplicable, must always remain as a stumbling-block to the majority
of those who have reached or passed middle life before its first
appearance.

Hardly anything is more characteristic of Darwin than the tone with
which he wrote to acknowledged opponents. Thus his letters to L.
Agassiz (1868), Quatrefages (1869 or 1870), and Fabre (1880), are
models of the way in which a correspondence which would present
peculiar difficulties to most people may be conducted. In these letters
there is not the least attempt to slur over or minimise the points of
wide difference; on the contrary, they are most candidly stated, but
with so much respect and sympathy, and with such marked appreciation
of the knowledge he had gained from his correspondent, that the reader
must have regretted the divergence of opinion as greatly as the writer.

Tyndall has given a very interesting and pathetic account of the
evident distress with which Professor L. Agassiz, chief of the
opponents of Darwin in America, recognised the success of the
teachings he could not accept.

      “Sprung from a race of theologians, this celebrated man combated
      to the last the theory of natural selection. One of the many
      times I had the pleasure of meeting him in the United States
      was at Mr. Winthrop’s beautiful residence at Brookline, near
      Boston. Rising from luncheon, we all halted, as if by a common
      impulse in front of a window, and continued there a discussion
      which had been started at table. The maple was in its autumn
      glory; and the exquisite beauty of the scene outside seemed, in
      my case, to interpenetrate without disturbance the intellectual
      action. Earnestly, almost sadly, Agassiz turned and said to the
      gentlemen standing round, ‘I confess that I was not prepared to
      see this theory received as it has been by the best intellects
      of our time. Its success is greater than I could have thought
      possible.’”[J]

The history of science can hardly supply anything more sad than the
blight which may fall on a man’s career because he is unable, from
conscientious motives, to use some great means of advance. Such a
weapon for the progress of science was provided by the Darwinian
theory, and men were to be henceforth divided according to their use
or neglect of the new opportunities. Men who up to that time had been
equals were to be for ever separated, some to press forward in the
front rank of scientific discovery, others to remain as interesting
relics of a byegone age.

It is hardly necessary to say that this does not apply to men, like
Agassiz, who had already left their mark deep upon the science of their
day, but it has a very real application to those men whose position
was to be estimated by work done after the year 1858.

In the midst of those years of struggle and anxiety which followed the
appearance of the “Origin,” we meet with another instance of the same
extraordinary foresight which appeared in his contention in favour of
the persistence of the great oceans and continental areas. I refer to
his views on spontaneous generation--a very ancient belief, and one
which from time to time has been the will-o’-the-wisp of biological
speculation, leading it into all kinds of fruitless and dangerous
regions.[K]

Dr. Carpenter’s “Introduction to the Study of Foraminifera” had been
reviewed in the _Athenæum_ (March 28th, 1863), the writer attacking
evolution and favouring spontaneous generation, or, as it was then
called, heterogeny. Darwin wrote to Hooker, who had lent him a copy of
the paper, “Who would have ever thought of the old stupid _Athenæum_
taking to Oken-like transcendental philosophy written in Owenian
style!... It will be some time before we see ‘slime, protoplasm, etc.,’
generating a new animal.... It is mere rubbish, thinking at present of
the origin of life; one might as well think of the origin of matter.”
In 1871 he wrote:--

      “It is often said that all the conditions for the first
      production of a living organism are now present, which could
      ever have been present. But if (and oh! what a big if!) we could
      conceive in some warm little pond, with all sorts of ammonia
      and phosphoric salts, light, heat, electricity, etc., present,
      that a proteine compound was chemically formed ready to undergo
      still more complex changes, at the present day such matter would
      be instantly devoured or absorbed, which would not have been the
      case before living creatures were formed.”

About 1870 Dr. H. C. Bastian began working on the subject, and brought
forward in his “Origin of Lowest Organisms” (1871), and “The Beginnings
of Life” (1872), what he believed to be conclusive evidence of the
truth of spontaneous generation, for which he proposed the term
Archebiosis. His enthusiasm and strong convictions were contagious, and
for a time the belief spread rather widely, although it soon collapsed
before the researches and arguments of Pasteur, Tyndall, and Huxley.
Darwin read “The Beginnings of Life,” and wrote about it to Wallace
(August 28th, 1872) as follows:--

      “His [Bastian’s] general argument in favour of Archebiosis is
      wonderfully strong, though I cannot think much of some few of
      his arguments. The result is that I am bewildered and astonished
      by his statements, but am not convinced, though, on the whole,
      it seems to me probable that Archebiosis is true. I am not
      convinced, partly I think owing to the deductive cast of much of
      his reasoning; and I know not why, but I never feel convinced
      by deduction, even in the case of H. Spencer’s writings.... I
      must have more evidence that germs, or the minutest fragments of
      the lowest forms, are always killed by 212° of Fahr.... As for
      Rotifers and Tardigrades being spontaneously generated, my mind
      can no more digest such statements, whether true or false, than
      my stomach can digest a lump of lead.”




CHAPTER XXI.

VARIATION OF ANIMALS AND PLANTS UNDER DOMESTICATION: PANGENESIS (1868).


We now come to consider the succession of invaluable works produced by
Darwin after the appearance of the “Origin,” the last of which--that on
Earthworms--was published about six months before his death.

Darwin’s method of bringing these results before the world was
somewhat different from that most generally adopted by scientific men
in this country, although of common occurrence in Germany. The great
majority of scientific facts are here published by the proceedings
or transactions of scientific societies, or in special journals; and
although a scientific man frequently brings together his general
results into a volume for the public, the original communications
remain as the detailed exposition of his researches.

Darwin, too, wrote a very large number of memoirs for the scientific
societies, as may be seen from the list in Appendix III. of the “Life
and Letters,” but the volumes which he subsequently published included
_all_ the previous details, with the addition of much new matter, and
it is these volumes rather than the original communications which form
the authoritative statement of his investigations. Such a method was
possible and desirable with the subjects upon which he worked, all
of which were of great interest to the thinking part of the general
public, as well as to the experts; but in less attractive subjects it
is not probable that the plan could be carried out in this country with
any prospect of success.

It has already been stated that Darwin looked on the “Origin of
Species” as a short abstract of a greater work he intended to publish.
It is likely that he at first contemplated a comprehensive work like
the “Origin” itself, but soon found that his notes on domesticated
animals and plants, the general results of which had been condensed
into the first three chapters of the “Origin,” would form a work
more than twice the size of the latter. He began arranging these
notes on January 9th, 1860 (January 1st is the date given in the
“Autobiography”), as soon as the second edition of the “Origin” was off
his hands, but his “enormous correspondence,” as he calls it in the
“Autobiography,” with friends about the “Origin,” and the reviews and
discussions upon it, must have occupied a large part of his time; and
then there was the third edition to bring out (published April, 1861).
This edition must have cost much labour, as many parts were modified
and enlarged to meet the objections or misunderstanding of reviewers.

Francis Darwin tells us that the third chapter of “Animals and Plants,
&c.,” was still on hand at the beginning of 1861. His work on this book
was furthermore interrupted by illnesses and by other researches.
Thus, during 1860 he worked at Drosera, and during the latter part
of 1861 and beginning of 1862 at the fertilisation of orchids. In
his diary for 1866 we meet with the entry, “_Nov. 21st_--Finished
‘Pangenesis,’” and later on, “_Dec. 22nd_--Began concluding chapter
of book.” In this year, too, he brought out the fourth edition of the
“Origin.” When the time for publication approached Darwin was much
disappointed at the dimensions of the work. It was not published till
January 30th, 1868, when it was proved that his fears were groundless,
for a second edition of 1,250 copies were required in the following
month, the 1,500 of the first edition having been all absorbed.

This work is considered by some writers to be the greatest produced by
Darwin; but I think we shall be right in accepting his own opinion that
such words should be applied to the “Origin.” It is probable, however,
that this book stands second in importance in the splendid list of
works which have done so much to increase our knowledge of nature and
to inspire others to continue the good work.

[Sidenote: ON VARIATION.]

“The Variation of Animals and Plants under Domestication” opens with
a very clearly written account of natural selection; it proceeds to
treat of the domestic quadrupeds and birds, describing the differences
between the various breeds of each species, and making out as far as
possible the history of their development from each other and from the
wild stock. Cultivated plants are then treated in the same manner.
The first volume concludes with two most important chapters on
bud-variation and anomalous modes of reproduction, and on inheritance.

The second volume deals with inheritance, crossing, effect of
conditions of life, sterility, hybridism, selection by man, causes
and laws of variability. Finally, all the main lines are brought to
a common centre in the wonderful chapter in which he discloses his
“provisional hypothesis of pangenesis.” This is of such interest,
and is so characteristic of its author’s power of viewing the most
divergent facts from a common standpoint, that it is desirable to give
a tolerably full account of it.

The following is a brief statement of the various classes of facts
which Darwin attempted to connect by his hypothesis.

_Reproduction_ is sexual and asexual, and the latter is of various
kinds, although their differences are more apparent than real. It may
be concluded that gemmation or budding, fission or division, the repair
of injuries, the maintenance of each part, and the growth of the embryo
“are all essentially the results of one and the same great power.”

In parthenogenesis the ovum can develop without fertilisation, and
hence the union of germs from different individuals cannot serve as
an essential characteristic of sexual, as compared with asexual,
generation. Although sexually-produced individuals tend to vary far
more than those which are produced asexually, this is not always the
case, and the variability, when it occurs, is subject to the same
laws. Sexually-produced individuals very generally pass in development
from a lower to a higher grade; but this can hardly be said to occur in
certain forms, such as Aphis, etc.

The differences between the two forms of reproduction being thus much
less than at first sight appears, we are led to inquire for the reason
why the more complex and difficult process is so universal. Sexual
reproduction appears to confer two benefits on organisms--(1) “When
species are rendered highly variable by changed conditions of life,
the free intercrossing of the varying individuals will tend to keep
each form fitted for its proper place in nature, and crossing can be
effected only by sexual generation”; (2) Many experiments tend to show
that free and wide intercrossing induces vigour in the offspring.

Darwin concludes that the reason why the germ-cell perishes if it does
not unite with another from the opposite sex is simply because it
includes “too little formative matter for independent existence and
development.” He was led to this conclusion by the fact that the male
and female germ-cells “do not in ordinary cases differ in their power
of giving character to the embryo,” and also from experiments which
seemed to show that a certain number of pollen grains or of spermatozoa
may be required to fertilise a single seed or ovum. “The belief that
it is the function of the spermatozoa to communicate life to the ovule
seems a strange one, seeing that the unimpregnated ovule is already
alive, and continues for a considerable time alive.”

It is very remarkable to note how largely Professor Weismann’s
conclusions on this subject were anticipated by this part of Darwin’s
work.

_Graft hybrids._--The probability that a graft may alter the character
of the stock to which it is united, so that hybrid buds might be formed
by budding or grafting the tissues of distinct varieties or species,
would, if it became a certainty, prove the essential identity of
sexual and asexual reproduction; “for the power of combining in the
offspring the characters of both parents is the most striking of all
the functions of sexual generation.”

_Direct action of the male element on the female._--Pollen from another
species is known to affect the mother-plant in certain cases. Thus
pollen from the lemon has caused stripes of lemon-peel in the fruit of
the orange; the peel is, of course, formed by the mother-plant, and
is quite different from the part which the male element is adapted to
affect--viz. the ovule. Similar cases are known among animals, as in
the celebrated example of Lord Morton’s mare.

_Development._--The changes by which the embryo reaches maturity
differ immensely, even within the limits of the same compact group.
Forms which closely resemble each other in the mature state, and
are intimately related to each other, such as the various species
of lobster and crayfish, etc., pass through a totally different
developmental history. Hence we are led to believe in the complete
independence of “each structure from that which precedes and follows it
in the course of development.”

_The functional independence of the elements or units of the body.
Variability and inheritance._--Variability generally results “from
changed conditions acting during successive generations.” The influence
is exerted on the sexual system, and if extreme, impotence tends to be
produced. Bud-variation proves that “variability is not necessarily
connected with the sexual system.” The inherited effects of use and
disuse of parts imply that the changes in the cells of a distant part
of the body affect the reproductive cells, so that the being produced
from one of these cells inherits the changes. “Nothing in the whole
circuit of physiology is more wonderful.”

“Inheritance is the rule and non-inheritance the anomaly.” Inheritance
follows laws, such as the tendency for a character to appear at
corresponding ages in parent and offspring. Reversion “proves to us
that the transmission of a character and its development ... are
distinct powers.” Crossing strongly induces reversion. “Every character
which occasionally reappears is present in a latent form in each
generation.”

       *       *       *       *       *

[Sidenote: PANGENESIS.]

The hypothesis of pangenesis attempts to explain and connect together
all the facts and conclusions which have been summarised in the
preceding pages. This hypothesis assumes that each one of the
countless cells of which the body of a higher animal is composed throws
off a minute gemmule which, with those derived from other cells, exists
in the body, and when supplied with nutriment multiplies by division.
Each gemmule is capable of ultimate development into a cell similar
to the one from which it, either directly or indirectly, arose. Each
cell of the body dispatches its representative, as it were, to each
single germ-cell, and this explains how it is that the latter possess
the power of reproducing the likeness of the parent body. But the
germ-cells also receive dormant gemmules which may remain undeveloped
until some generation in the remote future. The development of the
gemmules into cells depends on their union with the developing cells
which precede them in the order of growth. Gemmules are thrown off
during each stage of growth and during maturity.

This hypothesis of pangenesis is so called because the whole body is
supposed to produce the elements from which new individuals arise, the
germ-cells being only the union of these elements into clusters.

The fact that hybrids may be produced by grafting, that the pollen can
act on the tissues of the female plant, and the male germ-cells on the
future offspring of the female, implies that the reproductive material
can exist and the reproductive processes take place in the tissues, and
that they are not confined to the germ-cells.

The retention of dormant gemmules, and their passage from generation
to generation until their development, may seem improbable; but is it
more so than the _fact_ which their presence would explain--viz. the
transmission of latent structures and their ultimate reappearance?

The development of the whole plant from a Begonia leaf implies that
these gemmules are very widely distributed through the tissues.

The elective affinity of the gemmules for the cells which precede them
in growth may be paralleled by the affinity of the male and female
germ-cells, as we see in the preference of a plant for the pollen
grains of its own over those of closely-allied species, or by the
attraction of the minute germs of disease to certain tissues of the
body.

It is possible that the numerous gemmules thrown off by the cells of
a complex structure, such as a feather, “may be aggregated into a
compound gemmule.” In the case of a petal, however, where parts as well
as the whole are apt to develop, as is seen in the case of “stripes of
the calyx assuming the colour and texture of the corolla,” it is more
probable that the gemmules are separate and free. The cell itself is a
complex structure, and we do not know whether its separate parts are
not developed from the separate gemmules of an aggregate.

Such an hypothesis explains the fundamental similarity which has
already been shown to exist between all modes of reproduction. The
gemmules collected in bud or germ-cell are essentially similar;
and were it not for the special advantages of sexual reproduction
(increased vigour and more marked variation of offspring), we can well
believe that it would have been much less general. The formation of
graft-hybrids, and the action of the male element on the mother and on
future offspring, become intelligible. The antagonism between growth
and sexual reproduction in animals, and between increase by buds, etc.,
and seeds in plants, can be understood by the use of gemmules in one
direction preventing their simultaneous use in another.

The regrowth of an amputated part, as in the salamander or snail,
is explained by the presence and development of gemmules previously
thrown off from the part. The difficulty that a limb is produced of the
same age as that which was lost, and not a larval limb, and that the
cells with which the gemmules must unite at first are not those which
precede them in the course of growth, but mature cells, is met by the
consideration that this power is a special one adapted to meet special
dangers to certain parts of certain animals, and that it is therefore
probable that appropriate provision has been made by natural selection:
it may be in the form of “a stock of nascent cells or of partially
developed gemmules.” The existence of these latter in buds, and their
absence from sexual cells, may account for bud development being the
more direct and brief of the two. The much greater tendency to repair
lost parts in lower and younger forms may be due to the same cause.

The occasional tendency of hybrids to resemble one parent in one part
and the other in another may be due to superabundance of gemmules in
the fertilised germ, those from one parent having “some advantage in
number, affinity, or vigour over those derived from the other parent.”
The general preponderance of one parent over the other may be similarly
explained. The cases in which “the colour or other characters of either
parent tend to appear in stripes or blotches” are to be understood by
the gemmules having an affinity for others of the same kind.

_The sterility of hybrids_ is entirely due to the reproductive organs
being affected; in the case of plants they continue to propagate freely
by buds. The hybrid cells throw off hybrid gemmules which collect in
the buds but cannot do so in the reproductive organs.

_Development and metamorphosis._--The remarkable facts of development
and metamorphosis are well explained by the hypothesis. Allied forms
may pass to a similar end through very dissimilar stages or conversely.
Parts may appear to develop within previously existing corresponding
parts, or they may appear within parts which are quite distinct. These
divergent facts are explained by the hypothesis, each part during each
stage being formed independently from the gemmules of the same part
in previous generations, and not, although it may appear to do so,
from the corresponding parts of earlier stages. In the process of time
certain parts during certain stages may be affected by use or disuse or
surroundings, and the parts of subsequent generations will be similarly
affected, because formed from correspondingly altered gemmules; but
this need not affect the other stages of the same parts.

_Transposition and multiplication of parts._--The cases of abnormal
transposition or multiplication of organs--for instance, the
development of teeth in the palate or of pollen in the edge of a
petal--are to be explained by supposing that the gemmules unite with
wrong cells instead of, or as well as, the right ones; “and this would
follow from a slight change in their elective affinities.” Such slight
changes are known to occur; for instance, certain plants “absolutely
refuse to be fertilised by their own pollen, though abundantly fertile
with that of any other individual of the same species.” Inasmuch as the
cells of adjoining parts will often have nearly the same structure, we
can understand that some slight change in elective affinity may affect
a large area. Hence we can account for a crowd of horns on the head of
a sheep, or many spurs on the leg of a fowl, etc. Frequently repeated
parts are extremely liable to vary in number; in this case we have a
large number of closely allied gemmules and of points for their union,
and slight changes in elective affinity would be specially apt to
occur.

VARIABILITY.--Changed conditions may lead to irregularity in the number
of gemmules derived from various parts of the body; deficiency in
number might cause variation in any part by leaving some of the cells
free to unite with allied gemmules.

The direct action of surroundings, or the effect of use or disuse
on a part, may cause corresponding modifications of the gemmules,
and through these of the part in the succeeding generation. “A more
perplexing problem can hardly be proposed,” and yet it receives an
explanation on this hypothesis. Such causes must, as a rule, act during
many generations before the modification reappears in the offspring.
This may be due to the unaltered gemmules derived from earlier
generations, and their gradual replacement by the increasing number of
altered gemmules.

Variation in plants is much more frequent in sexually produced than it
is in asexually produced individuals. This may be due to the absence
in the latter of that great cause of variability, changes in the
reproductive organs under altered conditions. Furthermore, the former
alone pass through the earlier phases of development, when structure is
most plastic and yields most readily to the causes inducing variability.

The stability of hybrids and of many varieties when propagated by buds,
as compared with their reversion to the parent form when propagated by
seed, remains inexplicable.

Hence variability is explained as due (1) to the irregularity in
number of gemmules, to their transpositions, and redevelopment
when dormant; and (2) to their actual modification and the gradual
replacement by them of unaltered gemmules.

INHERITANCE.--The non-transmission by heredity of mutilations, even
when repeated for many generations, as in docking the tails of
certain domesticated breeds, may be explained by the persistence of
gemmules from still earlier generations. The cases of inheritance when
mutilations are followed by disease, as in Brown-Séquard’s experiments
on guinea-pigs, may be due to the gemmules being attracted to the
diseased part and there destroyed.

The disappearance of a rudimentary part, together with its occasional
reappearance by reversion, is to be understood by the existence of
ancestral gemmules, for which the corresponding cells have, except in
the cases of reversion, lost their affinity. When the disappearance is
final and complete, the gemmules have probably perished altogether.

“Most, or perhaps all, of the secondary characters which appertain to
one sex, lie dormant in the other sex; that is, gemmules capable of
development into the secondary male sexual characters are included
within the female; and conversely female characters in the male.” This
is seen in cases of castration or when the sexual organs from any cause
have become functionless. The sex in which such changes are brought
about tends to develop the secondary sexual characters of the other
sex. The normal development of the secondary characters proper to the
sex of the individual may be explained by a slight difference in the
elective affinity of the cells so that they attract the corresponding
gemmules rather than those of the opposite sex, which as we have seen
are also present.

The male characters of the male sex are in many species latent except
at certain seasons of the year, and in both sexes the proper characters
are latent until sexual maturity. All such latent characters are
closely connected with the cases of ordinary reversion. The appearance
(whether seasonal or in the course of development) of cells with
affinities for the latent gemmules explains the development of the
characters in question.

Certain butterflies and plants (_e.g._ Lythrum) produce two or
more separate forms of individuals. In these cases each individual
includes the latent gemmules of the other forms as well as its own.
Hermaphroditism in unisexual species, and especially in the occasional
cases of insects in which the right side of the body is one sex and the
left side the other, the line of separation dividing the individual
into two equal halves, can be explained by slight abnormal changes in
the affinities of cells for gemmules, so that a certain group of cells,
or all the cells on one side of the body, attract the gemmules which
would normally have remained latent.

Reversion is induced by a change of conditions and especially by
crossing. The first results of crossing are usually intermediate
between the parents, but in the next generation there is commonly
reversion to one or both parent-forms, or even to a more remote
ancestor. The existence of abundant hybridised gemmules is shown by the
propagation of the cross in a true form by means of buds; but dormant
gemmules from the parent-form are also present and multiply. In the
sexual elements of the hybrid there are both pure and hybrid gemmules,
and the addition of the pure gemmules in one sex to those in the other
accounts for the reversion, especially if we assume that pure “gemmules
of the same nature would be especially apt to combine.” Partial
reversion on the one hand, and the reappearance of the hybrid form on
the other, would be respectively due to a combination of pure with
hybrid gemmules, and of the hybrid gemmules from both parent hybrids.

When characters which do not blend exist in the parents, crossing
may result in an insufficiency of gemmules from the male alone and
from the female alone, and then dormant ancestral gemmules might have
the opportunity of development, and thus cause reversion. Similarly
certain conditions might favour the increase and development of
dormant gemmules. Diseases appearing in alternate generations, or
gaining strength by the intermission of a generation, may be due to
the increase of the gemmules in the intervening time, and the same
explanation may hold for the sudden and irregular increase of a weakly
inherited modification.

Darwin ends his general conclusions with these words:--

      “No other attempt, as far as I am aware, has been made,
      imperfect as this confessedly is, to connect under one point
      of view these several grand classes of facts. An organic
      being is a microcosm--a little universe, formed of a host of
      self-propagating organisms, inconceivably minute and numerous as
      the stars in heaven.”




CHAPTER XXII.

PANGENESIS AND CONTINUITY OF THE GERM-PLASM: DARWIN’S CONFIDENCE IN
PANGENESIS.


[Sidenote: PANGENESIS.]

Darwin’s letters prove that he thought very highly of this hypothesis;
and whether the future determine it to be true or erroneous, it must
surely rank as among the greatest of his intellectual efforts. In his
autobiography he says of it:--

      “An unverified hypothesis is of little or no value; but if any
      one should hereafter be led to make observations by which some
      such hypothesis could be established, I shall have done good
      service, as an astonishing number of isolated facts can be thus
      connected together and rendered intelligible.”

The hypothesis was submitted to Huxley (May 27th, 1865?) in manuscript
and alluded to in the letter sent at the same time. An unfavourable
reply was evidently received, for we find Darwin writing to Huxley,
July 12th (1865?):--

      “I do not doubt your judgment is perfectly just, and I will try
      to persuade myself not to publish. The whole affair is much too
      speculative; yet I think some such view will have to be adopted,
      when I call to mind such facts as the inherited effects of use
      and disuse, &c.”

This last sentence is of great interest, and the same opinion comes
out strongly in his published account of the hypothesis, viz. the
view that the real facts which imperatively demand some material to
pass from the body-cells to the germ-cells in order to account for
their hereditary transmission are the effects of use and disuse, or the
influence of surroundings--in fact, all those characters which are now
called “acquired.” And it is impossible to escape the conclusion that,
if acquired characters are transmissible by heredity, an hypothesis
which is substantially that of pangenesis will have to be accepted.
Darwin did not doubt this transmission, and he framed pangenesis mainly
to account for it.

Considerable doubt has of recent years been thrown upon the
transmission of acquired characters, and if hereafter this doubt
be justified, it will be possible to substitute for pangenesis a
hypothesis like the “continuity of the germ-plasm” brought forward by
Professor Weismann. A few words indicating the contrast between the two
hypotheses may not be out of place.

In Professor Weismann’s hypothesis the germ-plasm contained in the
nucleus of the germ-cell possesses, if placed under right conditions,
the power of developing into an organism. It is not, however, entirely
used up during development, and the part which remains grows and is
stored in the germ-cells of the offspring, and ultimately develops
into the succeeding generation. Hence parent and offspring resemble
each other because they are formed from the same thing. There is no
real break between the generations; they are thrown up successively
from a continuous line of germ-plasm. In this hypothesis the germ
is the essential thing, the body a mere secondary product. It is a
theory of Blastogenesis as contrasted with Pangenesis. The hereditary
transmission of acquired characters, in which many still believe, is
quite irreconcilable with it, and if substantiated would overthrow it
altogether.

On the other hand the body-cells are the essential elements of
pangenesis, and the germ-cells the mere meeting-places of their
representatives and quite devoid of significance on their own account.
There is some sort of interruption between successive generations, as
the gemmules develop into cells, which again throw off gemmules; the
break, however, is bridged by the ancestral gemmules and by the life of
the body-cell which intervenes between the gemmule from which it arose
and that to which it gives rise.

The remaining chief occasions on which Darwin alludes to pangenesis in
his published letters are quoted below; they prove his confidence in
the hypothesis and the nature of the hold it had upon his mind.

Later on he again wrote to Huxley on the same subject:--

      “I am rather ashamed of the whole affair, but not converted to a
      no-belief.... It is all rubbish to speculate as I have done; yet,
      if I ever have strength to publish my next book, I fear I shall
      not resist ‘Pangenesis,’ but I assure you I will put it humbly
      enough. The ordinary course of development of beings, such as the
      Echinodermata, in which new organs are formed at quite remote
      spots from the analogous previous parts, seems to me extremely
      difficult to reconcile on any view except the free diffusion in
      the parent of the germs or gemmules of each separate new organ:
      and so in cases of alternate generation.”

_To_ LYELL, _August 22nd, 1867_.

      “I have been particularly pleased that you have noticed
      Pangenesis. I do not know whether you ever had the feeling of
      having thought so much over a subject that you had lost all power
      of judging it. This is my case with Pangenesis (which is 26 or
      27 years old), but I am inclined to think that if it be admitted
      as a probable hypothesis it will be a somewhat important step in
      Biology.”

_To_ ASA GRAY, _October 16th, 1867_.

      “The chapter on what I call Pangenesis will be called a mad
      dream, and I shall be pretty well satisfied if you think it a
      dream worth publishing; but at the bottom of my own mind I think
      it contains a great truth.”

_To_ HOOKER, _November 17th_ [1867].

      “I shall be intensely anxious to hear what you think about
      Pangenesis; though I can see how fearfully imperfect, even in
      mere conjectural conclusions, it is; yet it has been an infinite
      satisfaction to me somehow to connect the various large groups of
      facts, which I have long considered, by an intelligible thread.”

_To_ FRITZ MÜLLER, _January 30th_ [1868].

      “... I should very much like to hear what you think of
      ‘Pangenesis,’ though I fear it will appear to _every one_ far too
      speculative.”

_To_ HOOKER, _February 23rd_ [1868].

After expressing a fear that Pangenesis is still-born because of the
difficulty with which it is understood, he says:--

      “You will think me very self-sufficient, when I declare that I
      feel _sure_ if Pangenesis is now still-born it will, thank God,
      at some future time reappear, begotten by some other father,
      and christened by some other name. Have you ever met with any
      tangible and clear view of what takes place in generation,
      whether by seeds or buds, or how a long-lost character can
      possibly reappear; or how the male element can possibly affect
      the mother plant, or the mother animal, so that her future
      progeny are affected? Now all these points and many others are
      connected together, whether truly or falsely is another question,
      by Pangenesis. You see I die hard, and stick up for my poor
      child.”

_To_ WALLACE, _February 27th_ [1868].

      “You cannot well imagine how much I have been pleased by what
      you say about ‘Pangenesis’.... What you say exactly and fully
      expresses my feeling, viz. that it is a relief to have some
      feasible explanation of the various facts, which can be given
      up as soon as any better hypothesis is found. It has certainly
      been an immense relief to my mind; for I have been stumbling over
      the subject for years, dimly seeing that some relation existed
      between the various classes of facts.... You have indeed pleased
      me, for I had given up the great god Pan as a still-born deity.”

_To_ HOOKER, _February 28th_ [1868].

      “I see clearly that any satisfaction which Pan may give will
      depend on the constitution of each man’s mind.... I heard
      yesterday from Wallace, who says (excuse horrid vanity), ‘I can
      hardly tell you how much I admire the chapter on “Pangenesis.” It
      is a _positive comfort_ to me to have any feasible explanation
      of a difficulty that has always been haunting me, and I shall
      never be able to give it up till a better one supplies its
      place, and that I think hardly possible, &c.’ Now his foregoing
      [italicised] words express my sentiments exactly and fully:
      though perhaps I feel the relief extra strongly from having
      during many years vainly attempted to form some hypothesis.
      When you or Huxley say that a single cell of a plant, or stump
      of an amputated limb, has the ‘potentiality’ of reproducing
      the whole--or ‘diffuses an influence,’ these words give me no
      positive idea;--but, when it is said that the cells of a plant,
      or stump, include atoms derived from every other cell of the
      whole organism and capable of development, I gain a distinct
      idea. But this idea would not be worth a rush, if it applied to
      one case alone; but it seems to me to apply to all the forms
      of reproduction--inheritance--metamorphosis--to the abnormal
      transposition of organs--to the direct action of the male
      element on the mother plant, &c. Therefore I fully believe that
      each cell does _actually_ throw off an atom or gemmule of its
      contents;--but whether or not, this hypothesis serves as a useful
      connecting link for various grand classes of physiological facts,
      which at present stand absolutely isolated.”

_To_ V. CARUS, _March 21st_ [1868].

      “... Sir C. Lyell says to every one, ‘You may not believe in
      “Pangenesis,” but if you once understand it, you will never get
      it out of your mind.’ And with this criticism I am perfectly
      content. All cases of inheritance and reversion and development
      now appear to me under a new light.”

_To_ FRITZ MÜLLER, _June, 1868_.

      “I have yet hopes that you will think well of Pangenesis. I feel
      sure that our minds are somewhat alike, and I find it a great
      relief to have some definite, though hypothetical view, when
      I reflect on the wonderful transformations of animals,--the
      re-growth of parts,--and especially the direct action of pollen
      on the mother-form, &c. It often appears to me almost certain
      that the characters of the parents are ‘photographed’ on the
      child, only by means of material atoms derived from each cell in
      both parents, and developed in the child.”

_To_ ASA GRAY, _May 8th_ [1868].

      “Your article in the _Nation_ [March 19th] seems to me very good,
      and you give an excellent idea of Pangenesis--an infant cherished
      by few as yet, except his tender parent, but which will live a
      long life. There is parental presumption for you!”

_To_ E. RAY LANKESTER, _March 15th_ [1870].

      “I was pleased to see you refer[L] to my much despised child,
      ‘Pangenesis,’ who I think will some day, under some better nurse,
      turn out a fine stripling.”

_To_ WALLACE, _August 28th, 1872_.

      “Notwithstanding all his [Dr. Bastian’s] sneers I do not strike
      my colours as yet about Pangenesis.”

In the second edition of “Animals and Plants,” Beale’s criticism
of the hypothesis is alluded to with characteristic candour and
humour:--“Dr. Lionel Beale (_Nature_, May 11th, 1871, p. 26) sneers
at the whole doctrine with much acerbity and some justice.” Galton’s
paper before the Royal Society (March 30th, 1871), upon the results of
inter-transfusion of blood as destructive of pangenesis, was answered
by Darwin in _Nature_ (April 27th, 1871). He did “not allow that
pangenesis has as yet received its death-blow, though from presenting
so many vulnerable points its life is always in jeopardy.”

Galton had argued that the gemmules present in the blood of one
individual would be expected to pass into the other individual and to
produce hereditary effects on its offspring. This, however, did not
occur. Romanes repeated these experiments under more rigid conditions,
but with the same negative results; equally negative were the effects
of his transplantation of skin from one animal to another, although the
skin grew quite successfully in its new position.




CHAPTER XXIII.

DESCENT OF MAN--EXPRESSION OF EMOTIONS--EARTH-WORMS (1871–81).


The work on “The Descent of Man” was begun as soon as Darwin had sent
the manuscript of “Animals and Plants” to the printers, although
notes on the subject had been collected from time to time during the
previous thirty years--in fact, ever since Darwin had come to definite
conclusions on evolution.

The book was published February 24th, 1871, but, as in the case of
his other publications, continuous work upon the manuscript had been
impossible. The volume attracted great interest, and 5,000 copies were
printed in 1871 in addition to the first 2,500.

The full title of the book is “The Descent of Man, and Selection in
Relation to Sex,” and, as this title almost implies, it is made up of
two distinct works, which might well have been issued separately. The
first part, dealing with man, is far shorter than the other. Darwin
had from the first considered that his theory of evolution by natural
selection would involve man as well as the other animals, and, that no
one might accuse him of want of candour, he had said in the “Origin”
that by this work “light would be thrown on the origin of man and his
history.” But he was anxious to justify this statement, which was, of
course, distasteful to very many in those days, by a most complete
treatment of the subject.

[Sidenote: DESCENT OF MAN.]

He opens this part of the work, which he calls “The Descent or Origin
of Man,” by discussing the structures which are common to man and
animals, including those which are represented in man in a rudimentary
state, and by showing the similarity of the phases through which man
and animals pass during their embryological development.

Having thus shown that man was probably descended from some lower
form, he considers the mode by which the process was effected, showing
that man possesses variability in body and mind, and is, like other
animals, subject to all the laws of inheritance and variation, and to
the direct action of surrounding conditions, and to the effect of the
use and disuse of parts, and that his rate of increase is such as to
render a large amount of extermination inevitable. In other words, he
presents the same facilities for the operation of natural selection as
those presented by other animals. The points in which man differs from
other animals are then considered in relation to their possible origin
by natural selection. The differences and resemblances between the mind
of man and animals are discussed in much detail, and the origin of the
former through natural selection is defended. This part concludes with
the consideration of the position of man in the animal series, his
birthplace and antiquity, and with an account of the formation of races.

In the second part Darwin brings forward a large body of evidence in
favour of his hypothesis of sexual selection--viz. the view that, in
the higher animals, some alteration, especially of the secondary sexual
characters, is produced by the preferences and rejections of the sex
which is sought by the other. Such results are commonly found in the
males as a result of the preferences of the females accumulated through
countless generations; but in some species the females court the males,
and are themselves subject to the same process of improvement by
selection.

Opinion is still divided on this most interesting question. Wallace,
more convinced than ever as to the efficiency and scope of natural
selection, after first doubting, has finally come to reject sexual
selection altogether. Probably the majority of naturalists are
convinced by Darwin’s arguments and his great array of facts that
the principle of sexual selection is real, and accounts for certain
relatively unimportant features in the higher animals, and they further
accept Darwin’s opinion that its action has always been entirely
subordinate to natural selection.

A brief third part considers sexual selection in relation to man.

Darwin says, in his “Autobiography,” that sexual selection and “the
variation of our domestic productions, together with the causes and
laws of variation, inheritance, and the intercrossing of plants, are
the sole subjects which I have been able to write about in full, so as
to use all the materials which I have collected.”

[Sidenote: EXPRESSION OF EMOTIONS.]

“The Expression of the Emotions,” at first intended as a chapter of the
“Descent,” was begun, only two days after the proofs of the latter had
been corrected, on January 15th, 1871. The book was published in the
autumn of the following year; the edition consisted of 7,000 copies,
and 2,000 were printed at the end of the year; and this, we are told,
was a mistake, as it prevented the appearance of a second edition, with
notes and corrections, during the author’s lifetime. Darwin had begun
to take notes on this subject when his first child was born, December
27th, 1839, for he tells us that, even then, he felt convinced “that
the most complex and fine shades of expression must all have had a
gradual and natural origin.”--(“Autobiography.”)

In this work Darwin argues with great wealth of illustration and the
record of numberless interesting observations, that the movements of
expression are to be explained by three principles. The first of these
is that movements made in gratifying some desire become by repetition
so habitual that the slightest feeling of desire leads to their
performance, however useless they may then be. The second principle
is that of antithesis--“the habit of voluntarily performing opposite
movements under opposite impulses.” The third principle is “the direct
action of the excited nervous system on the body, independently of the
will, and independently, in large part, of habit.”

By showing that the expressions of emotions could thus be explained
naturally, Darwin undermined the position taken up by Sir Charles Bell,
that the muscles used in producing expression were created for this
special end.

In 1876 he re-commenced geological work, bringing out his previous
works on “Volcanic Islands,” and on “South America,” as a single
volume. In this year too he wrote (November 16th) a most interesting
letter to James Geikie, offering an explanation of the large stones
standing in an upright position in the drift of the south of England.
He had noticed the same thing with the flints in the red clay left
upon the chalk as a residuum after the action of solvent agencies
on the latter. This position he explained was due to the movement
following the slow subsidence of parts of the clay as the chalk beneath
dissolved, the flints arranging themselves along the lines of least
resistance. This suggested to him the view that the flints in the drift
are to be explained by the subsidence, during the warmer climate which
followed the glacial period, of alternate layers of snow and drift
accumulated during the winters and summers respectively, of the cold
period itself.

This interesting view will, Geikie believes, come to be accepted as the
truth.

[Sidenote: WORK OF EARTH-WORMS.]

The book upon “The Formation of Vegetable Mould Through the Action
of Worms,” must be included among his geological works, although it
contains a great many observations of deep zoological interest. It
has been stated already that he wrote a paper on this subject for
the Geological Society in 1838. In 1877 he studied the mode by which
Roman remains gain their protective covering of mould; again towards
the end of 1880 he began systematically to prepare the book, which
was published on October 10th of the following year. It was extremely
successful, 8,500 copies being sold in three years.

This interesting work affords a good illustration of the tremendous
results obtained, even in a moderate time, by an immense number of
workers all using their powers in one direction. Each single earth-worm
swallows earth in the excavation of its burrow and for the nutriment
it contains, the waste material being ejected as “castings” at the
surface, and as a lining to the burrow. But although the amount of
earth thus swallowed by a single worm is not large, worms are so
numerous that “the whole of the superficial mould ... has passed, and
will again pass, every few years through the bodies of worms.” The
result of this unceasing transport of the deeper mould to the surface
is shown to be the burial of stones, either singly or in layers (as in
paths), the covering and consequent protection of ancient buildings,
and the preparation of soil for plants. In addition to this, the
geological denuding agencies are assisted by the manner in which the
deeper soil is brought into a position in which it is exposed to their
action.

In 1879 he wrote and published a life of his grandfather, Erasmus
Darwin, as “a preliminary notice” to the English translation of E.
Krause’s Life; but Darwin’s contribution forms the larger part of the
volume.




CHAPTER XXIV.

BOTANICAL WORKS (1862–86).


Darwin’s botanical works are referred to separately, and receive more
systematic treatment than the others, in the great “Life and Letters.”
They form, together with the botanical letters, the subject of the
seventh to the twelfth chapters in the last volume. It will therefore
be unnecessary to treat them in any detail, although they form some of
the most important and interesting of all his biological investigations.

_Fertilisation of flowers._--“The Fertilisation of Orchids” was the
first published of the botanical works, appearing in 1862, followed
by a second and greatly altered edition in 1877. The object of the
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 the
flowers with pollen brought by insects from a distant plant.” Even
in 1837 Darwin had written in his note-book, “Do not plants which
have male and female organs together [_i.e._ in the same flower] yet
receive influence from other plants? Does not Lyell give some argument
about varieties being difficult to keep [true] on account of pollen
from other plants? Because this may be applied to show all plants do
receive intermixture.” (Quoted in the “Life and Letters.”) In 1841,
Robert Brown, the distinguished botanist, advised Darwin to read
Sprengel’s “Secret of Nature Displayed” (Berlin, 1793). The result was
to encourage and assist Darwin in his work on fertilisation of flowers
by insects, and to bring about the first due recognition of Sprengel’s
merits, long after his death.

“_The Effects of Cross- and Self-fertilisation in the Vegetable
Kingdom._”--This work has a very direct bearing on that last mentioned.
Darwin speaks in the Autobiography “of having come [in 1839] to the
conclusion in my speculations on the origin of species, that crossing
played an important part in keeping specific forms constant.” Later
on he came to see that the advantage of crossing is more direct,
and results from the greater vigour of the offspring over those of
self-fertilised plants. The object of this work, published in 1876,
was to prove this point by experimental evidence of sufficient amount,
and to show in numerous cases, by measurements of height or weight,
or by counting the number of seeds produced, that cross-fertilisation
invariably tends towards the greater vigour of offspring.

Hence the motive cause for the marvellous adaptations by which
cross-fertilisation is ensured was supplied.

[Sidenote: FORMS OF FLOWERS.]

“_Different Forms of Flowers on Plants of the Same Species_” was
published in 1877, and a second edition in 1880. This work, like so
many others, had been largely anticipated by the author’s original
papers to scientific societies, in this case to the Linnean. The papers
were combined, brought up to date, and with the addition of much new
matter constituted the volume. The chief part of the work is concerned
with heterostyled plants, viz. species which bear different kinds of
flowers chiefly distinguished by the lengths of the pistil and stamens.
As many as three different forms occur in Lythrum. In this work it
is shown that each of the forms, although possessing both kinds of
sexual organs, is adapted to be fertilised by the pollen of another
form, and that such offspring are more vigorous than those produced
by fertilisation by the same form. He furthermore showed that the
offspring of “illegitimate” parentage (viz. those which were fertilised
by the same form) possessed, in certain respects, a close resemblance
to hybrids among animals. He remarks in his Autobiography, “No little
discovery of mine ever gave me so much pleasure as the making out the
meaning of heterostyled flowers.”

In addition to the heterostyled flowers, the other differing forms
borne by the same plants are considered, including the cleistogamic
species, in which minute closed flowers are borne as well as the
ordinary open ones. The former are wanting in the scents and colours
of ordinary flowers, and are specially adapted for self-fertilisation,
and the production of “an abundant supply of seeds with little
expenditure.”

“_Climbing Plants._”--The subject of this volume was published as a
paper before the Linnean Society in 1864. After being corrected, the
material was brought out as a volume in 1875. Darwin, as he tells us in
the Autobiography, was first led to study the subject by a paper by Asa
Gray, which appeared in 1858 (Proc. Amer. Acad. of Arts and Sciences).
Writing to Asa Gray, August 4th, 1863, he said, “My present hobby-horse
I owe to you, viz. the tendrils.” One of the most interesting results
brought forward in this work is the fact that the upper growing part
of a twining stem bends to one side and then travels slowly round,
between two and three hours being required for each revolution, in the
case of the hop growing in a room and observed at the period of most
active movement. The circle swept at the 27th revolution was 19 inches
in diameter. In the case of this plant the three youngest internodes
(or joints), and never less than two of them, were concerned in the
movement; “by the time the lower one ceased to revolve, the one above
was in full action, with a terminal internode just commencing to move.”
The object of this movement is to strike some object round which
the plant may twine. A much grander example was seen in _Ceropegia
Gardnerii_, in which three long internodes and two short ones swept a
circle over 5 feet in diameter, “at the rate of 32 or 33 inches per
hour, in search of some object round which to twine.” The stem of the
plant is not in the least twisted by this movement. Nearly all of the
great divisions of twining plants, leaf-climbers, and tendril-bearers
“have the same remarkable power of spontaneously revolving.”

[Sidenote: MOVEMENT IN PLANTS.]

“_The Power of Movements in Plants_” was published on November 6th,
1880. It embodies a vast amount of work carried on in conjunction with
Francis Darwin. This volume bears a very direct relation to that last
mentioned, as Darwin has explained in his Autobiography:--

      “In accordance with the principle of evolution it was impossible
      to account for climbing plants having been developed in so many
      widely different groups unless all kinds of plants possess
      some slight power of movement of an analogous kind. This I
      proved to be the case; and I was further led to a rather wide
      generalisation, viz. that the great and important classes of
      movements, excited by light, the attraction of gravity, &c., are
      all modified forms of the fundamental movement of circumnutation.”

An extreme example of circumnutation has already been described in the
revolving movements of the youngest parts of the stem of a twining
plant.

The work evoked very great interest in this country, but was severely
criticised by certain German botanists. The immense number of new
observations must always have a very high value, whatever be the fate
of the general conclusions, concerning which it may be remarked that
Darwin’s conclusions have often been criticised before, but time has
shown that he was right.

“_Insectivorous Plants_” was published July 2nd, 1875, but I consider
it last, as the subject stands somewhat apart from the rest of his
botanical works. The subject was suggested to him by noticing the
insects caught by the leaves of the Sun-dew (_Drosera_) near Hartfield.
He then studied in great detail the causes of the movement, and the
sensitiveness of the gland-tipped hairs, finding that a piece of hair
weighing 1/78000 of a grain causes one of them to curve inwards, and
alters “the condition of the contents of every cell in the foot-stalk
of the gland.”

The greater part of the work deals with the experiments on _Drosera_,
which were extremely numerous and detailed. The remainder treats of
other insectivorous plants, such as Dionæa, Pinguicula, Utricularia,
etc. The methods of capture, the movements of the plants under the
stimulus supplied by the living insect (or other animal), and the
resulting changes in the plant-cells were not the only points studied.
He also investigated the digestive secretion and its action upon the
food absorbed by the leaves.




CHAPTER XXV.

LETTERS FROM DARWIN TO PROFESSOR MELDOLA (1871–82).


By the kindness of my friend Professor Meldola, and the courtesy of
Mr. Francis Darwin, I am enabled to publish for the first time a
series of letters written by Charles Darwin to the former. The whole
series consists of 33 letters, written between January 28th, 1871, and
February 2nd, 1882, only a few weeks before his death.

When we remember the immense amount of correspondence with which Darwin
had to cope, the constant attention required by his investigations and
publications, and the state of his health, it is deeply interesting
to read these letters, written with such unfailing courtesy, to a
younger worker in the lines that he had suggested, and who was thereby
stimulated and encouraged to undertake the researches which are now so
well known.

Reading these letters and remembering the circumstances of the writer,
we can understand how it is that, although ill-health prevented his
presence on occasions at which the younger scientific men are wont
to meet--although he was known to but few of them--nevertheless the
charm of his noble and generous nature was a most potent force in
influencing and attracting men; and it was this, no less than his
epoch-making discoveries, which has made it one of the chief regrets of
many a scientific worker that he never saw Charles Darwin.

[Sidenote: LETTERS.]

The correspondence was opened by a letter from Meldola informing Darwin
of a case of hexadactylism in a man at Turnham Green.

      “_Jan. 28 [1871]._

                                                  “Down.

      “DEAR SIR,--I am much obliged for your kindness in informing me
      of the hexadactylous case; but so many have been recorded that I
      do not think, except under very special circumstances, it would
      be worth your while further to investigate it.

      “With my thanks, yours faithfully and obliged,

                                                  “CH. DARWIN.”


The next letter refers to Meldola’s communication to _Nature_ (he
had recently written upon pangenesis and upon sexual selection),
and his work on mimicry, protective resemblance, etc. In the latter
part we meet with an interesting reference to the researches on
cross-fertilisation which are now so famous.

      “_June 9th [1871]._

                                                  “Down.

      “DEAR SIR,--I am greatly obliged by your note. I have read with
      much interest and carefully perused your letter in Nature, and
      am looking out for a paper announced for Linn. Soc. Your remarks
      shall all be in due time fully considered. With respect to the
      separation of the sexes, I have often reflected on the subject;
      but there is much difficulty, as it seems to me and as Nageli has
      insisted, inasmuch as a strong case can be made out in favour of
      the view that with plants at least the sexes were primordially
      distinct, then became in many cases united, and in not a few
      cases re-separated. I have during the last 5 or 6 years been
      making a most laborious series of experiments, by which I shall
      be able, I think, to demonstrate the wonderful good derived from
      crossing, and I am almost sure but shall not know till the end
      of the summer that I shall be able to prove that the good is
      precisely of the same kind which the adult individual derives
      from _slight_ changes of conditions.

      “With my sincere thanks for your interest in my work, I remain,
      dear Sir, Yours very faithfully,

                                                  “CH. DARWIN.”


The following letter is of great interest in relation to many problems
of sexual selection, protective resemblance, mimicry, etc.:--

      “_Jan. 23, 1872._

                                                  “Down.

      “DEAR SIR--The point to which you refer seems to me a very
      difficult one. 1^{st} the comparison of the amount of variability
      in itself would be difficult. 2^{ndly} of all characters,
      colour seems to be the most variable, as we see in domesticated
      productions. (3) I fully agree that selection if long continued
      gives fixity to characters. We see the reverse of this in the
      great variability of fancy races, now being selected by man.
      But to give fixity, selection must be continued for a very long
      period: pray consider on this head what I have said in the Origin
      about the variability of characters developed in an extraordinary
      manner, in comparison with the same characters in allied species.
      The selection must also be for a definite object, and not for
      anything so vague as beauty, or for the superiority of one male
      in its weapons over another male, which can in like manner be
      modified. This at least seems to me partly to account for the
      general variability of secondary sexual characters. In the case
      of mimetic insects, there is another element of doubt, as the
      imitated form may be undergoing change which will be followed by
      the imitating form. This latter consideration seems to me, as
      remarked in my ‘Descent of Man,’ to throw much light on how the
      process of imitation first began.

      “I enclose a letter from Fritz Müller which I think is well worth
      reading, and which please to return to me.

      “You will see he lays much stress on the difficulty of several
      remotely allied forms all imitating some one species. Mr. Wallace
      did not think that there was so much weight in this objection
      as I do. It is, however, possible that a few species in widely
      different groups, before they had diverged much, should have
      accidentally resembled, to a certain extent, some one species.
      You will also see in this letter a strange speculation, which I
      should not dare to publish, about the appreciation of certain
      colours being developed in those species which frequently behold
      other forms similarly ornamented. I do not feel at all sure that
      this view is as incredible as it may at first appear. Similar
      ideas have passed through my mind when considering the dull
      colours of all the organisms which inhabit dull-coloured regions,
      such as Patagonia and the Galapagos Is. I suppose you know Mr.
      Riley’s excellent essay on mimicry in the last report on the
      noxious insects of Missouri or some such title.

      “I hope your work may be in every way successful.

          “I remain, dear Sir, yours faithfully,
                                                  “CHARLES DARWIN.”


The next letter deals with mimetic resemblance:--

      “_Mar. 28, 1872._

                                                  “Down.

      “DEAR SIR--I thank you for your information on various subjects.
      The point to which you allude seems to me very obscure, and I
      hardly venture to express an opinion on it. My first impression
      is that the colour of an imitating form might be modified to
      any extent without any tendency being given to the retention
      of ancient structural peculiarities. The difficulty of the
      subject seems to me to follow from our complete ignorance of the
      causes which have led to the generic differences between the
      imitating and imitated forms. The subject however seems worth
      investigating. If the imitator habitually lives in company with
      the imitated, it would be apt to follow in some respects the same
      habits of life, and this perhaps would lead to the retention or
      acquirement of some of the same structural characters.

      “I wish you all success in your essay, and remain, dear Sir,
      yours very faithfully,

                                                  “CH. DARWIN.”


The next very brief letter, acknowledging the receipt of a note, was
written from Down, March 26th, 1873. It contained some sympathetic
remarks upon the progress of Meldola’s work upon Mimicry. In the
succeeding letter, printed below, we find a very definite statement of
opinion as to the _rôle_ of monstrosities in evolution:--

      “_Aug. 13th_ [1873].

                                                  “Down.

      “DEAR SIR--I am much obliged for your present which no doubt I
      shall find at Down on my return home....

      “I am sorry to say that I cannot answer your question; nor do
      I believe that you could find it anywhere even approximately
      answered. It is very difficult or impossible to define what is
      meant by a larger variation. Such graduate into monstrosities
      or generally injurious variations. I do not myself believe that
      these are often or ever taken advantage of under nature. It is a
      common occurrence that _abrupt_ and considerable variations are
      transmitted in an unaltered state, or not at all transmitted,
      to the offspring or to some of them. So it is with tailless or
      hornless animals, and with sudden and great changes of colour in
      flowers.--I wish I could have given you any answer.

            “Dear Sir, yours very faithfully,
                                                  “CH. DARWIN.”


The succeeding three letters show Darwin’s scrupulous care as regards
the publication, although with every acknowledgment, of the results
obtained by others. They refer to a letter from Fritz Müller which
he had forwarded to Meldola. The latter had written to ask Darwin’s
permission and advice as to the inclusion of some of F. Müller’s
observations in his most interesting paper, “Entomological Notes
bearing on Evolution” (_Ann. and Mag. Nat. Hist._, 1878, 5th series,
Vol. I. p. 155), which he was then preparing:--

      “_Sept. 14, 1877._

                                                  “Down.

      “DEAR SIR--I have some doubts whether Fritz Müller would like
      extracts from his letters being published after so long an
      interval,--that is if the letter relates to the origin of
      mimicry; for he published about a year ago an excellent paper on
      this subject. I believe it was in the Jenaische Zeitschrift, but
      the paper is out of its proper place in my library and I cannot
      find it. If you thought it worth while to send me your copy I
      could then judge about the publication of extracts.

      “I fear it is not likely that I shall have anything to
      communicate to the Entomological Soc. I quite agree with you
      that it is a great pity that our Entomologists should confine
      themselves to describing species.

              “Dear Sir, yours faithfully,
                                                  “CH. DARWIN.”


       *       *       *       *       *

      “_Sept. 22nd_ [1877].

                                                  “Down.

      “MY DEAR SIR--I am doubtful whether speculations in a letter
      ought to be published, especially after a long interval of time.
      Any fact which he states, I feel pretty sure he would not at
      all object being used by anyone.--Pray do the best you can.--I
      should grieve beyond measure to be accused of a breach of
      confidence.--He has lately, as I mentioned, thrown much light on
      the first steps in mimicry.

      “With respect to dimorphic Butterflies, those about which I have
      read appear at different seasons, and have been the subject of an
      _admirable_ essay by Prof. Weismann. It is some little time since
      I read the essay and one subject drives another out of my head,
      but I think he explains all such cases by the direct inherited
      effects of temperature. He tried experiments. If you read
      German, I believe I could find Weismann’s essays and lend them to
      you. In your present interesting case I really do not know what
      to think: it seems rather bold to attribute the 2 coloured forms
      to nat. selection, before some advantage can be pointed out.--May
      not the female revert in some cases? I do not doubt that the
      intermediate form could be eliminated as you suggest.

      “I wish that my opinion could have been of any value....

              “I remain yours very faithfully,
                                                  “CH. DARWIN.”


This last letter, with others that followed it, directing Meldola’s
attention to Weismann’s “Studies in the Theory of Descent,” resulted
in the English translation which is so admirably rendered and edited.
Many of the later letters are concerned with the progress of this
publication. The remarks about dimorphic butterflies referred to
Meldola’s observation, that in one of those years in which _Colias
edusa_ was extremely abundant, a whole series of forms had been taken
transitional between the normal orange female and the white variety
_helice_:--

      “_Sept. 27_ [1877].

                                                  “Down.

      “MY DEAR SIR,--It is impossible for F. M. [Fritz Müller] to
      object to anything which you have said in your very interesting
      little essay.--I just allude to Butterflies preferring certain
      colours at p. 317 of 2nd Edit^{n.} of the Descent and to the case
      of the species of Castnia p. 315 which has ornamented hinder
      wings and displays them, whilst 2 other species have plain
      hind wings and do not display them. My son, who has charge of
      my library, returns home to-night and then we will search for
      Weismann. He gives splendid case of caterpillar with coloured
      ocelli like true eyes, _and which frightened away birds_.

              “Yours sincerely,
                                                  “CH. DARWIN.”


The reference in this letter is to Meldola’s paper, “Entomological
Notes bearing on Evolution,” soon afterwards published in the _Annals
and Magazine of Natural History_, 1878, Vol. I. p. 155. The caterpillar
referred to is the well-known larva of the Large Elephant Hawk Moth
(_Chærocampa elpenor_).

Darwin then wrote a brief note (October 19th, 1877) referring to a
number of _Kosmos_ containing an article on “Sexual Selection.” He
offered to send the number if it would interest his correspondent. The
number was sent, as the succeeding letter shows:--

      “_Oct. 22nd [1877]._

                                                  “Down.

      “MY DEAR SIR,--I send Kosmos by this post....

      “Prof. Weismann’s address is Freiburg.--I should think he
      would be glad of translation, and would probably arrange for
      stereotypes of Plates.--You could say as an introduction that I
      had lent you his book.--To find a publisher will be perhaps a
      difficulty. Should it be translated I must beg you to get another
      copy, as I cannot spare mine for such a length of time.--Wallace
      sent me his article and I was quite dissatisfied with it.--To
      explain a peacock’s tail by vital activity seems to me mere
      verbiage--a mere metaphysical principle.

              “My dear Sir, yours faithfully,
                                                  “CH. DARWIN.

      “It will be a public benefit to bring out a translation.”

Then followed three letters, January 3rd, March 24th, and March 27th,
1878; the first written when Darwin was sending another number of
_Kosmos_, the second when sending his photograph, the third enclosing a
letter from Fritz Müller containing some very interesting observations
on mimicry in South American butterflies.

He then wrote as follows:--

      “_April 17/78._

                                                  “Down.

      “MY DEAR SIR,--I should be very much obliged if you could get
      some one to name the photographs of the enclosed insect and read
      the enclosed letter. It seems a pretty, but I think not new
      case of protective resemblance. One might fancy that the large
      ocelli on the under wings were a sexual ornament.--Perhaps these
      photographs might be worth exhibiting at the Entomolog. Soc.--I
      do not want them returned (unless indeed Dr. Zacharias wants them
      back, which is not probable) or the enclosed letter.

      “A single word with the name of the genus and if possible of the
      species, would suffice.--

      “Pray forgive my troubling you and believe me

              “Yours faithfully,
                                                  “CH. DARWIN.

      “I am glad that F. Müller’s letter interested you. He has
      published a paper with plates on the shape of the hairs or scales
      on the odoriferous glands of many butterflies, which I could send
      you, but I doubt whether you would care for it.”

Darwin then sent another letter from Fritz Müller containing some
interesting notes on odoriferous organs in butterflies, and on the
occasional failure of the female insect to deposit her eggs on a plant
which can serve as the food of the young larvæ. The beetles alluded to
were a species of _Spermophagus_. The two letters printed below refer
to the same subjects:--

      “_May 15 [1878]._

                                                  “Down.

      “MY DEAR SIR,--I think the enclosed will interest you.--The
      letter to me need not be returned as I have had the only
      important passage for my work copied out.--In the letter F. M.
      [Fritz Müller] sent me seeds of _Cassia neglecta_ and several
      beetles arrived alive, having formed their cocoons, and gnawed
      their way out of the little peas or seeds.--These elegant
      beetles, with the knowledge of their manner of development may
      interest some Coleopterist.

      “I hope to hear some time about Dr. Zacharias’ photographs. I
      received your obliging letter from Paris.

              “Yours sincerely,
                                                  “CH. DARWIN.”


       *       *       *       *       *

      “_May 25 [1878]._

                                                  “Down.

      “MY DEAR SIR,--The living beetles and the cocoons were found in
      a small paper packet containing the seeds. Those from which the
      beetles had emerged were much broken, and the larvæ had evidently
      attacked some of the other seeds. I am sorry to say that some of
      the injured ones were thrown away. I am glad that you are going
      to draw up a paper from Fritz Müller’s letters.

              “Yours sincerely,
                                                  “CH. DARWIN.”


After another short note, dated July 24th, 1878, Darwin wrote the
following letter, which explains how it was that he came to write the
preface to the translation of Weismann’s “Studies”:--

      “_October 31 [1878]._

                                                  “Down.

      “MY DEAR SIR,--As you are inclined to be so very liberal as to
      have a translation made of Weismann’s Essays on your own risk,
      I feel bound to aid you to the small extent of writing a short
      prefatory notice. But this is a kind of job, which I do not
      feel that I can do at all well and therefore do not like; but I
      will do my best. It must, however, be short for I am at present
      working very hard. I do not quite understand whether you intend
      asking some Publisher to bring out the book on commission at
      your cost for if so there will be no difficulty in finding a
      Publisher. But if you expect any Publisher to publish at his
      risk and cost; I think from recent experience you will have
      much difficulty in finding one.--I suppose that you have asked
      Weismann’s concurrence.

      “Down is rather an awkward place to reach, as we are 4 miles
      from nearest station, Orpington. But I shall be in London for a
      week on Nov^r 17th or 18th and could see you then at any time,
      and perhaps you could come to luncheon.

      “But if you would prefer to come here, I shall be very happy
      to see you either Saturday or Sunday, if you would let me know
      hour.--I am, however, bound to tell you that my health is always
      doubtful, and that my head does not allow me to converse long
      with anyone.

      “With the most cordial sympathy in your undertaking, I remain, my
      dear Sir, yours very faithfully,

                                                  “CH. DARWIN.”


In November, 1878, Darwin was in London, staying at his daughter’s
house at 4, Bryanston Street. On the 19th he wrote asking Meldola to
lunch to talk over the proposed English edition of Weismann, and on the
25th sent the MS. of the Preface with the following letter:--


                                                  “4 Bryanston St.,
                                                      “Portman Sq^{re}.

      “_Nov. 25_ [1878].

      “MY DEAR SIR,--I send my little Preface, which I do not at all
      like, but which I cannot improve. I should like hereafter to
      see it in type. Mr. Bates tells me that Hardwick and Bohn of
      Piccadilly intend to go in for publishing solid books; and if
      your present publisher should change his mind: Mr. Bohn might be
      worth applying to.

              “Yours sincerely,
                                                  “CH. DARWIN.”

Professor Meldola then wrote, suggesting that Darwin should, in his
Preface, point out, by references to the “Origin of Species” and his
other writings, how far he had already traced out the lines which
Weismann had pursued in his researches. The suggestion was made because
in a great many of the Continental writings upon the theory of descent
a number of the points which had been clearly foreshadowed, and in
some cases even explicitly stated, by Darwin had been independently
rediscovered and published as though original. In the editorial notes
to Meldola’s translation full justice to Darwin has been done in this
respect. Darwin’s characteristic reply is deeply interesting.

      “_Nov 26^{th}_ [1878].

                                                  “4 Bryanston St.

      “MY DEAR SIR,--I am very sorry to say that I cannot agree to your
      suggestion.--An author is never a fit judge of his own work, and
      I should dislike extremely pointing out when and how Weismann’s
      conclusions and work, agreed with my own.--I feel sure that I
      ought not to do this, and it would be to me an intolerable task.
      Nor does it seem to me the proper office of the Preface, which
      is to show what the book contains and that the contents appear
      to me valuable. But I can see no objection for you, if you think
      fit, to write an introduction with remarks or criticisms of any
      kind. Of course I would be glad to advise you on any point as far
      as lay in my power, but as a whole I could have nothing to do
      with it, on the grounds above specified that an author cannot and
      ought not to attempt to judge his own works or compare them with
      others. I am sorry to refuse to do anything which you wish.--

      “We return home early to-morrow morning.--Your green silk seems
      to me a splendid colour, whatever the æsthetics may say.--My dear
      Sir, yours faithfully,

                                                  “CH. DARWIN.”


The “green silk” referred to some specimens of coal-tar colours sent
to show Darwin what modern chemistry had been able to accomplish in
the way of artificial colouring matters. They were at that time of
particular interest in connection with a discussion which had arisen
in Bryanston Street about the so-called “æsthetic” school, which
had become rather predominant at the period, and which affected an
abhorrence of all brilliant colouring, in spite of the circumstance
that nature abounds in the most gorgeous hues, especially in the
tropics.

The next letter refers to the adoption of the word “phyletic” in the
translation of Weismann.

      “_Dec. 14_ [1878].

                                                  “Down.

      “MY DEAR SIR,--I am very glad that you are making good progress
      with the book.--You could not apply to a worse person than myself
      on any philological question. I presume that ‘phyletische’ has
      been adopted or modified from Häckel. As the latter uses the
      word, it has nearly the sense of genealogical. It always applies
      to the lines of descent, and therefore differs somewhat from
      ‘innate’; for an inherited character, though derived from the
      father alone or only a single generation, would be innate in the
      child. I should think ‘phyletic’ would do very well, if you gave
      the German word and an explanation, in a foot-note.

      “There has been a delay in answering your letter, but I have just
      heard from my son who is away from home, and he says that he is
      sorry but he cannot well spare the time to lecture.

              “My dear Sir, yours very faithfully,
                                                  “CH. DARWIN.”


Then followed two letters (January 20th, and February 7th, 1879), the
first written when Darwin was sending a number of _Kosmos_; the second
referring to it and other papers, and asking that his name should be
put down as a subscriber to the forthcoming translation of Weismann.

Later on the number of _Kosmos_ for May, 1879, was sent, containing
(p. 100) Fritz Müller’s paper “_Ituna_ and _Thyridia_.” This paper,
although it did not attract sufficient attention at the time, was of
the highest importance in relation to the theory of mimicry, as Meldola
at once perceived.

Bates in his epoch-making paper in the Transactions of the Linnean
Society (Vol. XXIII. 1862) had founded the theory of mimicry.
Those rarer forms which have diverged from their near allies and,
in superficial appearance, approached some distantly related, but
abundant, species inhabiting the same tract have been, according to
Bates’s theory, benefiting themselves in the struggle for existence.
The mimicked species are, he suggested, abundant because they possess
some special means of protection, such as an unpleasant taste or smell,
and they have an unpleasant reputation which greatly aids them in the
struggle for life; while the mimicking species, by their superficial
resemblance, are enabled to live upon that reputation without
possessing the special means of defence.

Certain facts well-known to Bates, and brought forward in his paper,
were not explicable by this theory, viz. the resemblance that
often exists between the abundant and specially protected species
themselves. Although a few tentative suggestions were made, such as the
production of a common appearance by similarity of climate, or food,
etc., these facts remained an unexplained mystery until this paper
of Fritz Müller’s in the May number of _Kosmos_. He there suggests
that the mutual resemblance between the specially protected forms is
advantageous, in reducing for each of them the number of individuals
which must be sacrificed during the process of education which their
youthful enemies must undergo, before they learn what is fit and what
unfit for food. The arrangement is, in fact, much like that between a
couple of firms that issue a common advertisement, and so save about
half the expense of advertising alone. It is only another added to the
numerous examples of the production by natural selection, and without
the introduction of consciousness, of a result which could not be
bettered by the deliberate action of the most acute intelligence.

Meldola at once wrote to Darwin asking his advice about the translation
of F. Müller’s paper, and received the following reply:--

      “_June 6th, 1879._

                                                  “Down.

      “MY DEAR MR. MELDOLA,--Your best plan will be to write to ‘Dr.
      Ernst Krause, Friedenstrasse, 10 II. Berlin.’ He is one of the
      editors with whom I have corresponded. You can say that I sent
      you the Journal and called your attention to the paper, but I
      cannot take the liberty of advising the supply of clichés. He is
      a very obliging man. Had you not better ask for permission to
      translate, saying the source will be fully acknowledged?

      “F. Müller’s view of the mutual protection was quite new to me.

              “Yours sincerely,
                                                  “CH. DARWIN.”


The clichés were obtained and Meldola’s translation published in the
Proceedings of the Entomological Society for 1879, p. 20. The new
contribution to the theory of mimicry was at first somewhat severely
criticised, even Bates being adverse to it. Subsequent work has
abundantly justified it as by far the most important addition to the
subject since Bates’s original paper. In fact, many cases which have
been up to the present explained under the theory of true (Batesian)
mimicry are now believed to come under that which we owe to F.
Müller--viz. convergence between specially protected forms for mutual
benefit.

An interesting paper by Dr. F. A. Dixey, published in the Transactions
of the Entomological Society for the present year (1896), contains
convincing arguments in favour of this view as regards some of the
_Pieridæ_ of South America in relation to the _Heliconidæ_ and
_Papilionidæ_ which they resemble.

It is of the highest interest to learn that the first introduction
of this new and most suggestive hypothesis into this country was due
to the direct influence of Darwin himself, who brought it before the
notice of the one man who was likely to appreciate it at its true value
and to find the means for its presentation to English naturalists.

In the next year Meldola wished to translate further papers of Fritz
Müller’s, and received the following letter on the subject:--

      “_Nov. 25/80._

                                                  “Down.

      “MY DEAR SIR,--I can well believe that your labour must have been
      great, and everyone is bound to aid you in any way.

      “No. I. of F. Müller’s paper is in the August no. for 1877.

      “No. II.--is in the October no. for 1877.

      “Both these articles I remember thinking excellent.

      “I am not one of the editors of Kosmos, only a kind of patron(!)
      and therefore cannot give permission; but when you write to the
      editors you can say that I have expressed a hope that permission
      would be granted, you acknowledging source of papers.

      “Heartily wishing you success and in haste to catch first post, I
      remain yours very faithfully,

                                                  “CH. DARWIN.”


Shortly after the date of the last letter Professor Meldola came across
a copy of Thomson’s “Annals of Philosophy” on a bookstall. It bore the
name “Erasmus Darwin” on the first page, and Meldola offered it to
Charles Darwin, thinking it might have belonged to his grandfather.

      “_March 12th, 1881_ [The date was evidently May, and not March].

                                                  “Down.

      “DEAR MR. MELDOLA,--It is very kind of you to offer to send me
      the book, but I feel sure that it could not have belonged to
      my grandfather.--My eldest brother’s name is Erasmus and he
      attended to chemistry when young, and I suppose that the ‘Annals
      of Philosophy’ was left at my Father’s house and sold with the
      Library which belonged to my sisters.--I will look to the few
      words of Preface to Wiesmann [_sic_], whenever I receive a
      proof.--With many thanks.--

              “Yours very faithfully,
                                                  “CH. DARWIN.”


Then followed a brief note dated “Aug. 8, 1881,” referring to some
point in the work upon which Meldola was then engaged, and which cannot
now be ascertained. Another letter of the same date referred to the
translation of Weismann, and contained some encouraging words upon the
interest created by the work and upon the success of the Essex Field
Club, in which Meldola had taken a leading part. Another brief note of
August 10th, 1881, apparently refers to some paper which cannot now be
identified.

The following interesting letter is of uncertain date:--

      “_? 19th, ? 1881._

                                                  “Down.

      “DEAR MR. MELDOLA,--When I read the F. M. [Fritz Müller] paper
      your doubt occurred to me and I must say this, I would rather
      have expected that the knowledge of distasteful caterpillars
      would have been inherited, but I distinctly remember an account
      (when Wallace first propounded his warning colors) published of
      some birds, I think turkeys, being experimented upon and they
      shook their heads after trying some caterpillars as if they had a
      horrid taste in their mouths. I fancied this thing was published
      by Mr. Weir or could it have been by Mr. Butler? It would be well
      to look in Mr. Belt’s ‘Nicaragua’ as he tried some experiments. I
      am not sure that there is not some statement of the kind in it.

              “Yours faithfully,
                                                  “CHARLES DARWIN.

      “I daresay Mr. Wallace or Bates would remember the statement of
      some birds shaking their heads to which I refer.”

The statement about the turkeys evidently refers to Stainton’s
experiment with young birds of this kind, which immediately devoured
numerous protectively coloured moths, but, after seizing, invariably
rejected, a conspicuous white species (_Spilosoma menthastri_). It was
Belt’s ducks which shook their heads after tasting a very conspicuous
Nicaraguan frog. Darwin wished to show by this evidence that there was
no instinctive knowledge such as would have saved the birds from an
evidently unpleasant experience.

The last letter, deeply interesting both on its own account and because
it was written so near the end of Darwin’s life, was a reply to one
from Meldola in which he had said that the publishers were complaining
that the list of subscribers was disappointing, and that they had
expressed the wish that Mr. Darwin could see his way to writing a much
longer introductory notice than he had done.

      “_Feb. 2nd [1882]._

                                                  “Down.

      “DEAR MR. MELDOLA,--I am very sorry that I can add nothing to
      my very brief notice without reading again Weismann’s work and
      getting up the whole subject by reading my own and other books,
      and for so much labour I have not strength. I have now been
      working at other subjects for some years, and when a man grows
      as old as I am, it is a great wrench to his brain to go back to
      old and half-forgotten subjects. You would not readily believe
      how often I am asked questions of all kinds, and quite lately I
      have had to give up much time to do a work, not at all concerning
      myself, but which I did not like to refuse. I must however
      somewhere draw the line, or my life will be a misery to me.

      “I have read your Preface and it seems to me _excellent_. I
      am sorry in many ways, including the honour of England as a
      scientific country, that your translation has as yet sold badly.
      Does the publisher or do you lose by it? If the publisher, though
      I should be sorry for him, yet it is in the way of business; but
      if you yourself lose by it, I earnestly beg you to allow me to
      subscribe a trifle, viz. ten guineas, towards the expense of this
      work, which you have undertaken on public grounds.

              “Pray believe me, yours very faithfully,
                                                  “CH. DARWIN.”


Darwin’s generous offer, although gratefully declined, was a warm
encouragement in the laborious, and in some respects thankless, task of
translator and editor--a task which, in the case of the English edition
of Weismann’s “Studies in the Theory of Descent,” was carried out in so
admirable a manner.




CHAPTER XXVI.

HIS LAST ILLNESS (1882).


In the last few months of his life, towards the end of 1881 and
beginning of 1882, Darwin began to suffer from his heart, causing
attacks of pain and faintness which increased in number. On March 7th,
1882, he had one of these seizures when walking, “and this was the last
time that he was able to reach his favourite ‘sand-walk’” (“Life and
Letters”). After this he became rather better, and on April 17th was
able to record the progress of an experiment for his son Francis. The
following sentences are quoted from the “Life and Letters”:--

      “During the night of April 18th, about a quarter to twelve, he
      had a severe attack and passed into a faint, from which he was
      brought back to consciousness with very great difficulty. He
      seemed to recognise the approach of death, and said, ‘I am not
      the least afraid to die.’ All the next morning he suffered from
      terrible nausea and faintness, and hardly rallied before the end
      came.

      “He died at about four o’clock on Wednesday, April 19th, 1882.”

He was buried in Westminster Abbey on April 26th.

Thus died one of the greatest of men, after a life of patient and
continuous work interrupted only by ill-health; a man who was, perhaps,
more widely attacked and more grossly misrepresented than any other,
but who lived to see his teachings almost universally received; a
man whose quiet, peaceful life of work, and whose precarious health,
prevented that large intercourse with his fellow-men which is generally
forced upon greatness, but who was so beloved by his circle of intimate
friends that, through their contagious enthusiasm, and through the
glimpses of his nature revealed in his writings, he was in all
likelihood more greatly loved than any other man of his time by those
who knew him not.

And for all those of us who have loved Darwin, although we have never
seen him, we can at any rate remember that we have lived in his time
and have heard the echoes of his living voice; he has been even more
to us than he will be to future generations of mankind--a mighty
tradition, gaining rather than losing in force and in overwhelming
interest as each passing age, inspired by his example, guided by his
teachings, adds to the knowledge of nature, and in so doing gives an
ever deeper meaning to his life and work.




FOOTNOTES


[A] See Professor Meldola’s interesting Presidential Address to the
Entomological Society of London (January, 1896) on the use of the
imagination in science, printed in the Transactions of the Society and
in _Nature_. See also “The Advancement of Science” (London, 1890), in
which Professor Lankester maintains (p. 4): “All true science deals
with speculation and hypothesis, and acknowledges as its most valued
servant--its indispensable ally and helpmeet--that which our German
friends call ‘Phantasie’ and we ‘the Imagination.’” Consult also
Professor Tyndall’s essay “On the Scientific Use of the Imagination”
(“Fragments of Science,” 1889, vol. ii., p. 101).

[B] We are told in the “Life and Letters” that the last proof of the
“Journal” was finished in 1837. The Diary, as stated above, was written
between July, 1837, and February, 1838.

[C] Professor H. F. Osborn has rightly urged that this essay should be
published (“From the Greeks to Darwin,” 1894, p. 235).

[D] My friend Mr. J. J. Walker, R.N., tells me that the house in which
Wallace lived in Ternate, and in which the essay was written, is still
pointed out by the natives as one of the features of the place. It is,
unfortunately, much dilapidated.

[E] Wallace has added the following note to the reprint in “Natural
Selection and Tropical Nature,” London, 1891, p. 31: “That is, they
will vary, and the variations which tend to adapt them to the wild
state, and therefore approximate them to wild animals, will be
preserved. Those individuals which do not vary sufficiently will
perish.”

[F] Since the above paragraph was written I have again read Professor
Newton’s eloquent Address to the Biological Section of the British
Association at Manchester in 1887, and find that he says on the
same subject--“If in future you should meet with any cynic who may
point the finger of scorn at the petty quarrels in which naturalists
unfortunately at times engage, particularly in regard to the priority
of their discoveries, you can always refer him to this greatest of all
cases, where scientific rivalry not only did not interfere with, but
even strengthened, the good-feeling which existed between two of the
most original investigators” (Report of Meeting, p. 731).

[G] “There is grandeur in this view of life, with its several powers,
having been originally breathed by the Creator into a few forms or into
one;...”--(Concluding paragraph of “Origin,” 1860, p. 490.)

[H] “Life of Lord Sherbrooke,” Vol. II. (pp. 205–206), Longmans & Co.
London, 1893.

[I] Proc. Roy. Soc. Edin., Jan. 16th, 1860.

[J] Presidential address to the British Association at Belfast, 1874.
Report, p. lxxxvii.

[K] See H. F. Osborn, “From the Greeks to Darwin” (1894).

[L] In “Comparative Longevity.”




INDEX.


  Abnormal Transposition, or Multiplication of Parts, 172

  Acquired Characters, Transmission of, 179, 180

  Agassiz, Prof. L., and Darwin, 157, 158

  Animals, Variation of, under Domestication, 75, 115, 161, _et seq._;
    Abnormal Transposition or Multiplication of Parts, 172;
    Instinctive Knowledge in, denied, 216

  Argyll, Duke of, on Natural Selection, 144

  Atlantis Hypothesis, The, Darwin’s Objections to, 53–55


  Bastian, Dr. H. C., 160

  Bates on Mimicry, 212

  Bateson on Speculation and Hypothesis in Science, 14–15

  “Beagle,” Darwin’s Voyage in the, 21–24;
    Important Observations and Discoveries, 23;
    Countries and Islands visited, 23–24;
    Completion of “A Naturalist’s Voyage,” 30;
    Zoology of, 31;
    Geology of, 35

  Beale, Dr. Lionel, 184

  Bear and Whale, a Hypothetical Illustration of Natural Selection, 151

  Beetles, Wingless, 51

  Birds, Experimenting with Distasteful Caterpillars, &c., 216

  Botanical Works of Darwin, 193, _et seq._

  Bree, Dr., “Species not Transmutable,” 149

  Butler, Dr., School at Shrewsbury, Darwin’s Education at, 16, 17

  Butterflies, Dimorphic, 204, 205


  Cambridge, Darwin studying at, 18–20;
    Revisited, 25

  Carpenter, Dr., 159

  Carus, V., 183

  Case, Mr., Darwin attends his School at Shrewsbury, 16

  “Challenger” Expedition, The, 53, 55

  Cirripedia, Monographs on the, 36

  Climbing Plants, 196;
    Revolution of the Upper Part, 196

  Copley Medal of the Royal Society awarded to Charles Darwin, 109;
    to Sir Joseph Hooker, 111

  Coral Reefs, Work upon the, 32;
    Theory of Origin, 33;
    Dr. John Murray rejects the Darwinian Theory, 33

  Creative Hypothesis, Huxley on the, 135

  Crossing in Plants, The Advantages of, 194

  Cross-fertilisation in Plants, 201


  Darwin, Charles, Birthplace, 9;
    His Parentage, 10;
    Family Genius, 10;
    Secret of his Strength, 13–15;
    his high Valuation of Hypothesis, 14;
    Boyhood, 16–17;
    School-life, 16;
    Love of Sport, 16;
    at Edinburgh, 17;
    Dislike of Dissection, 17;
    First Scientific Discovery and Paper, 17, 18;
    at Cambridge, 18–20;
    his Friendship with Professors Henslow and Sedgwick, 19;
    Voyage of the “Beagle,” 21, _et seq._;
    Preparation for and Effects of the Voyage, 22;
    the Most Important Discoveries during, 23;
    Places Visited, 23, 24;
    Re-visits Cambridge, 25;
    Work upon the Collections, and the “Naturalist’s Voyage,” 25;
    at London, 25;
    Origin of Species, 25–29;
    Geological Work, 29, 33;
    Completion of “A Naturalist’s Voyage,” 30;
    Zoology of the Voyage of the “Beagle,” 31;
    Papers on Earth-Worms, 31;
    Marriage, 32;
    Book on the Coral Reefs, 32;
    Ill-health, 32;
    at Down, 35;
    his Career as a Biologist, 37;
    Systematic Work, 37;
    his Dislike of Species-mongers, 39, 40;
    Death of his Father and Daughter, 41;
    Growth of the Origin of Species Theory, 42–59;
    Correspondence with Friends, 50–59;
    Experiments with Seeds in Salt Water, 51, 52;
    Letter to Wedgwood, 52;
    Objections to the Atlantis Hypothesis, 53, 55;
    Letter to Lyell, 53;
    Friendship and Correspondence with Wallace, 60–64, 81–86;
    their Joint Papers Presented to the Linnean Society, 46, 62;
    Letter to Asa Gray on Selection, 68–70;
    Comparison and Reception of the Joint Papers, 78–82;
    Delay in Publishing his Discoveries, 90;
    Preparation of Origin of Species, 95, _et seq._;
    Observations, 96;
    Appeals to Lyell, 97;
    Letter to John Murray, 97;
    his Influence upon Lyell, 105;
    Receives the Copley Medal of the Royal Society, 109;
    his Indebtedness to Lyell’s Teaching, 110;
    Influence upon Hooker and Asa Gray, 111;
    his Controversy with Asa Gray, 114–118;
    his Influence upon Huxley, 119–143;
    his Views of Natural Selection as the Cause of Evolution not
        accepted by Huxley, 121–128;
    Extracts from Letters showing Difficulty with which Natural
        Selection was Understood, 145, _et seq._;
    on Spontaneous Generation, 108, 159;
    and Bastian, 160;
    his Later Works, 161;
    his Theory of Pangenesis, 163, _et seq._;
    Variation of Animals and Plants under Domestication, Outline of the
        Book, 163;
    on Sexual and Asexual Reproductions, 164, _et seq._;
    Extracts from Letters to Friends on Pangenesis, 178, _et seq._;
    “The Descent of Man,” 186;
    “The Expression of the Emotions,” 189;
    “Volcanic Islands,” 190;
    “South America,” 190;
    “The Formation of Vegetable Mould through the Action of Worms,” 191;
    his Life of Erasmus Darwin, 192;
    “Fertilisation of Orchids,” 193;
    Cross- and Self-Fertilisation in the Vegetable Kingdom, 194;
    Different Forms of Flowers on Plants of Same Species, 194;
    Climbing Plants, 196;
    “Power of Movement in Plants,” 197;
    “Insectivorous Plants,” 198;
    Letters to Prof. Meldola, 199, _et seq._;
    his Last Illness, 219;
    and Death, 220

  Darwin, Erasmus, Brother of Charles, 11

  Darwin, Erasmus, Grandfather of Charles, 10, 192

  Darwin, Prof. George, Brother of Charles, 11

  Darwin, Robert Waring, Father of Charles, 10;
    Profession and Character, 10;
    his Dislike to the “Beagle” Expedition, 21–22;
    Death of, 41

  Darwin Medal of the Royal Society awarded to Huxley, The, 140

  Darwinism not Evolution, Huxley’s Speeches, 139–141

  Deposits, Oceanic, 55

  Descent of Man, The, 186

  Development, 166, 171

  Dixey, Dr. F. A., Paper on Mimicry, 214

  Domestication, Variation by, of Animals and Plants, 115, 161, _et
        seq._;
    of Animals, 75

  Down, Darwin’s Home at, 35

  Drosera and Other Insectivorous Plants, 198


  Earthworms, 191;
    Castings of, 191;
    Papers on the, 31

  Edinburgh, Darwin studying for Medicine at, 17

  “Emotions, The Expression of the,” 189, 190

  Evolution, First Recorded Thoughts upon, 28;
    Natural Selection as a Cause not accepted by Huxley, 121, _et seq._;
    the Argument for, 100;
    supported by Huxley, 121;
    Huxley agrees with Darwin, 121, _et seq._;
    Discussion at Meeting of the British Association, 82, 138;
    not Darwinism, 139–141

  “Expression of the Emotions, The,” 189, 190

  Extinction, 43–45


  Fertilisation of Germ Cells, 165;
    “of Orchids, The,” 193;
    of Flowers by Insects, 193;
    Effects of Cross- and Self-, 194

  Fitzroy, Capt., of the “Beagle,” 21, 22

  Flowers, The Fertilisation of, by Insects, 193;
    Effects of Cross- and Self-Fertilisation compared, 194;
    Different Forms on the same Plant, 195

  Flustra, Darwin’s Discovery of the Free-Swimming Larvæ of, 18

  Forbes, Edward, and the Atlantis Hypothesis, 53

  “Formation of Vegetable Mould through the Action of Worms, The,” 191

  Fox, W. Darwin, 19


  Galapagos Archipelago, The Animals, etc., of the, 26, 27, 42

  Galton, F., 184

  Geikie, James, 190

  Geological Society, The, Darwin appointed Secretary, 29;
    Papers on the Earthworms, 31

  Geology of the Voyage of the “Beagle,” 35

  Glacial Phenomena, Darwin’s Paper upon, 33

  Graft-Hybrids, 166

  Grafting, Production of Hybrids by, 168

  Gray, Asa, Darwin’s Correspondence with, 51, 55, 107, 181, 184;
    his Influence upon, 112;
    Darwin’s Controversy with, 114–118

  Gray, Dr., 146, 149


  Henslow, Prof., Friendship with Darwin, 18–21

  Herbert, J. M., on Darwin’s Character, 19, 20

  Hereditary Genius, Evidences in the Darwin Family, 10, 11

  Heredity, Theories of, 167, 174

  Hermaphroditism, 175

  Holmes, Dr. Oliver Wendell, his References to Darwin, 9;
    his Correction of Darwin, 9

  Hooker, Sir Joseph, 37, 48;
    Darwin’s Letters to, on Species-mongers, 39–40;
    Darwin’s Opinion of, 48;
    Friendship and Correspondence with Darwin, 50;
    Lyell’s Correspondence with, as to Specific Centres, 57;
    Darwin’s Influence upon, 110, _et seq._;
    awarded the Copley Medal of the Royal Society, 111;
    and Darwin, 146;
    Darwin Writing on Pangenesis, 181, 182

  Huxley, Prof., Criticisms of Darwin’s Theory, 46, 48;
    on Teleology, 113;
    Darwin’s Influence upon, 119–143;
    agrees with Darwin on Evolution, 121;
    Views on Natural Selection, 121, 124, 126, 138;
    Article in the _Times_ on the Origin of Species, 124;
    his Article in the _Westminster Review_, 125;
    Lectures on the Causes of the Phenomena of Organic Nature, 128, 142;
    Views as to Natural Selection not changed, 137, 138;
    Speech at the British Association Meeting at Oxford, 139;
    awarded the Darwin Medal of the Royal Society, 140;
    Darwinism, not Evolution, 140, 141;
    and the Bishop of Oxford, 155

  Hybrid Grafts, 166

  Hybridism, 175, 176

  Hybrids, Tendency to Resemble one Parent, 171;
    Sterility of, 171;
    Produced by Grafting, 168

  Hypothesis and Speculation, Bearing on Science, 14, 15


  Inheritance, The Theories of, 167, 174

  Insectivorous Plants, 198

  Instinctive Knowledge in Animals denied by Darwin, 216


  Jenkin, Fleming, 81


  Lamarck’s Theory of Evolution, 99;
    Comparison with Darwin’s, 148, 150

  Lankester, Prof. E. Ray, 99, 184

  Linnean Society, Joint Memoirs by Darwin and Wallace, read before,
        65, _et seq._

  Lowe, Robert, 150

  Lyell, Sir Charles, Influence on Darwin, 29, 30, 51;
    and Continental Extensions, 53;
    and Hooker’s Agreement on the Specific Centres Theory, 57;
    Darwin’s Appeal to, on the Natural Selection, 97;
    Influence of Darwin upon, 105;
    Accepts Darwin’s Views, 108, 109;
    Death of, 109;
    Darwin’s Letter on Pangenesis, 181

  Lythrum, Different Forms of Flowers on the, 195


  Macleay, W. S., 150

  Malthus on Population, its Influence on Darwin, 46;
    and on Wallace, 88, 89

  Man, The Descent of, 186

  Meldola, Prof., on Systematic Work, 37;
    and Darwin, 199, _et seq._

  Metamorphosis, 171

  Mimetic Resemblance, 202

  Mimicry, 202, 204;
    Bates’ Theory, 212;
    Fritz Müller’s Theory, 212;
    Dixey’s paper on, 214

  Müller, Fritz, Darwin’s Letters to, 181, 183;
    on Mimicry, 212–214;
    his Paper Translated, 213

  Murray, Andrew, 152

  Murray, Dr. John, Controversy as to the Origin of Coral Reefs, 33


  Naming of Species, Darwin on the, 39, 40

  Natural Selection, Early Impressions on Darwin, 30, 45, 46;
    Survival of the Fittest, 56;
    Specific Centres, 57;
    Darwin’s Paper on, 65;
    Theory of, 68–70;
    Wallace’s Discovery of, 88–91;
    Lord Salisbury’s Attack on, 82, 138;
    Canon Tristram, the First Publicly to Accept the Theory, 92–94;
    Argument for, 100–103;
    Huxley not convinced as to Sufficiency of the Evidence of, 121,
        123, 124, 126;
    as the Highest Attempt to Account for Evolution, 129;
    Huxley’s Description of the Theory, 136, 137;
    H. C. Watson on, 144;
    Hostile Criticisms, 144, _et seq._;
    Why the Term was Chosen, 147

  “Naturalist’s Voyage, A,” Completion of, 30

  Newton, Prof., Speech at the British Association, 153

  _Nineteenth Century_, The Duke of Argyll’s Article in the, 144


  Orchids, the Fertilisation of, 193

  Origin of Species, Darwin’s Theory of the;
    Early Reflections upon, 25–29;
    Growth of the Theory, 42;
    Separate Creation Theory Inadequate, 42;
    Principles of Development, 45;
    First Account of Darwin’s Theory, 46;
    the Sketch Enlarged, 46;
    Profs. Huxley and Newton’s Criticisms, 46, 47;
    Divergence of Character, 47, 48;
    Competition, 47, 56;
    Darwin’s Arrangements for the Publication in case of his Death, 48;
    Darwin and Wallace’s Joint Paper Presented to the Linnean Society,
        46, 62;
    his Confidence, 48;
    Correspondence with Friends, 50;
    Immutability of Species denied, 50;
    Theory not understood by Naturalists, 55;
    the Polyphyletic Theory, 57;
    Specific Centres, 57;
    Darwin and Wallace, 60;
    their Papers before the Linnean Society, 62–77;
    Struggle for Life, 65–77;
    Principles of, 68–70;
    Comparison of the Joint Memoir, 78, _et seq._;
    Preparation of the Work on, 95, _et seq._;
    Interest of Lyell and Hooker in its Publication, 95;
    Letters to John Murray, the Publisher, 97;
    full Title of the Volume, 98;
    Outline of the Book and its Various Editions, 100–104;
    its Reception by Lyell, 105;
    by Hooker, 111;
    by Asa Gray, 112;
    and by Huxley, 119;
    Huxley’s Article in the _Times_, 124;
    and in the _Westminster Review_, 125;
    Huxley’s high Tribute to Darwin’s Theory, 130;
    Difficulty with which Understood, 144, _et seq._;
    Regarded by Darwin as an Abstract of a Larger Work, 162

  Osborn, Prof., 79, 80

  Oxford, the Bishop of, and Huxley, 155


  Pangenesis, Darwin’s Hypothesis of, 164, _et seq._;
    his Confidence in the Theory, 180, _et seq._

  Parallel Roads of Glen Roy, The, 31

  Parthenogenesis, 164

  Petrels at St. Kilda, West Indian nuts found in, 96

  Plants and Animals, Variation of, under Domestication, 161;
    Production of Abnormal Parts, 172;
    Separate forms on same Individual, 175;
    Different forms of Flowers on the same Species, 194;
    Climbing, 196;
    Power of Movements in, 197;
    Insectivorous, 198

  Pollen, Fertilisation of Ovule, 166

  “Power of Movements in Plants, The,” 197

  Protective Mimicry, 203


  Reproduction of an Amputated Limb or part, 170

  Reproduction, Sexual and Asexual, 164, _et seq._

  Reversion, 167, 175

  Rolleston, Prof., 155, 156

  Romanes, Prof. G. J., 185


  Salisbury, Lord, Speech at the British Association Meeting at Oxford,
        82, 83, 138

  Scientific Discoverer, The Qualifications of a, 12

  Seeds, Experiments on the Vitality of, in Salt-Water, 51, 52

  Sedgwick, Prof., Darwin’s Friendship with, 18;
    his Excursions with, 20

  Sexual and Asexual Reproduction, 164, _et seq._;
    Advantages of, 165;
    Cross-Fertilisation in Plants, 166;
    Characters, 174–177;
    Selection Theory, 67, 188, _et seq._;
    rejected by Wallace, 188;
    Darwin’s Letter to Meldola, 201

  Shrewsbury, Darwin’s Birthplace, 9;
    and School-life at, 16;
    Re-visited, 25

  “South America,” 190

  South America, Some Observations on the Geology of, 26

  Species, New, The Origin of, 56, _et seq._;
    “Species not Transmutable,” Dr. Bree’s Book, 149

  Species-mongers, Darwin’s Dislike of, 39, 40

  Speculation and Hypothesis, 14, 15

  Spencer, Herbert, Term of Survival of the Fittest, 148

  Spontaneous Generation, 108, 159

  Sterility of Hybrids, 171

  Struggle for Existence, The, 65–67, 71–77

  Survival of the Fittest, The, 148


  Teleology, 113, 114

  Ternate, Wallace’s house at, 63

  _Times_, Huxley’s Article on the Origin of Species in, 124

  Transmutation of Species, 26, 149

  Tristram, Canon, 92–94;
    Paper on Ornithology of Northern Africa, 92

  Tuckwell, Rev. W., 155

  Turkeys, Experimenting upon with Distasteful Caterpillars, 216

  Tyndall, Prof., 157


  Use and Disuse, The Inherited Effects of, 167, 179


  Variability, 167, 173

  Variation, of Organic Being, Darwin’s Papers upon, 65;
    Wallace’s Paper on, 71, _et seq._;
    and Selection Relative Importance of, 96;
    Under Domestication, 115, 161

  Varieties, Departure from the Original Type, 71–77

  “Volcanic Islands,” 190


  Wallace, Alfred Russel, and Darwin’s Joint Paper Presented to Linnean
        Society, 46, 62;
    and Darwin, 53, 60–64, 81–86, 134;
    Paper Published on the Law Regulating new Species, 60;
    Essays on Variations from Original Type, 61, 71–77;
    house at Ternate, 63;
    Comparison of the Joint Memoir, 78–86;
    his Discovery of Natural Selection, 87–91;
    Darwin’s Letter on Bastian’s Theory of Archebiosis, 160;
    Darwin’s Letter to, on Pangenesis, 182

  Watson, H. C., 144

  Wedgwood, Josiah, 18

  Weismann, Prof., on Germ-Plasm, 179;
    “Studies in the Theory of Descent,” Meldola’s Translation, 205–210

  _Westminster Review_, Huxley’s Article on Origin of Species in, 125

  Wilberforce, Bishop, 149


  Zoology of the Voyage of the “Beagle,” The, 31


PRINTED BY CASSELL & COMPANY, LIMITED, LA BELLE SAUVAGE, LONDON, E.C.




      *      *      *      *      *      *




Transcriber’s note:

Punctuation, hyphenation, and spelling were made consistent when a
predominant preference was found in the original book; otherwise they
were not changed.

Simple typographical errors were corrected; unpaired quotation
marks were remedied when the change was obvious, and otherwise left
unpaired.

Running page headers in the original book are shown here as sidenotes.

Dates and locations in the headings of letters usually were on the same
line in the original book, but have been placed on separate lines here.

Footnotes, originally at the bottoms of pages, have been collected,
resequenced, and placed just above the Index.

The Index was not checked for proper alphabetization or correct page
references.

Cover created by Transcriber and placed into the Public Domain.

Page 197: The correct title of “The Power of Movements in Plants” is
“The Power of Movement in Plants.”

*** END OF THE PROJECT GUTENBERG EBOOK 65779 ***