3937109 S,13VHOIW “iS 40 ALISH3ZAIND
o yl
EX LIBRIS.
Hertram C. A. Windle,
, BS. MB. F.G.A.
ee
bg)
+ - unrelenting Darwinian, a “ whole-hogger ” in the com-
mon parlance of the day. Others may say that Dar-
winism is “‘ on its death-bed,” or, like Driesch, may tell ©
us that it no longer ‘‘ manages to lead a whole genera- —
tion by the nose,” or, like Bateson, assure us that the
theory of Natural Selection ‘“ descended like a numbing
spell” on the study of species and varieties by means
of hybridism. Professor Poulton will have none of this and
- still holds by the ancient Darwinian faith in all its purity.
He believes, for we may assume that he is to be identi-
fied with “ the Darwinian ”’ to whom the views are im-
puted, ‘‘ that the finished product or species is gradually —
built up by the environmental selection of minute
increments, holding that, among inborn variations of all
degrees of magnitude, the small and not the large become
the steps by which evolution proceeds, He attempts to
avoid, as Darwin did, on the hand, the error of ascribing
the species-forming forces wholly to a creative environ-
.-Ment, and, on the other, the perhaps more dangerous —
error of ascribing them wholly to creative internal ten-
dencies ” (p. xiii). Thus he is absolutely opposed to the
Mutationist School, which refuses to see any importance
in minute variations from a developmental point of view
_and assigns all changes of species to sudden considerable
changes or mutations, which, in a word, believes in dis-
" continuotis, as opposed to continuous, evolution. It is
unnecessary to say that Professor Poulton’s conclusions —
are urged in graceful language and supported by constant
__ appeal to examples, and our only regret is that his pages }
are not wholly free from the odium scientificum which one
meets with from time to time, especially where what —
should be the peaceful name of Mendel comes into —
- question. This is a book to be read with interest, since it —
represents a side, though not perhaps one increasing in ~
numbers and weight, in the Darwinian controversy of the —
| day. _ BiC.A.W.
.
;
‘ Digitized by the Internet Archive
in 2007 with funding from
Microsoft Corporation
w
a.
t.
os A
— CHARLES DARWIN AND
. ~ THE ORIGIN OF SPECIES
ADDRESSES, ETC., IN AMERICA AND ENGLAND
IN THE YEAR OF THE 'TWO ANNIVERSARIES
BY
EDWARD BAGNALL POULTON, D.Sc., M.A.
How. LL.D. Parxceroy, F.R.S., V-P.L.S., F.Z.S., F.G.S., F.E.S.
HOPE PROFESSOR OF ZOOLOGY IN THE UNIVERSITY OF OXFORD
FELLOW OF JESUS COLLEGE, OXFORD
MEMB, HON. 800, ENT. BELG, ; 800, HON. REAL S00, ESPAN, HIST. NAT,
CORRESP, MEMB. ACAD. SCI., NEW YORK, AND 800. NAT. HIST. BOSTON
AUTHOR OF ‘ESSAYS ON EVOLUTION’, ETC.
PUBLISHED NOV. 24, 1909, BEING THE FIFTIETH ANNIVERSARY
OF THE PUBLICATION OF ‘THE ORIGIN OF SPECIES’
LONGMANS, GREEN, AND CO.
39 PATERNOSTER ROW, LONDON
NEW YORK, BOMBAY, AND CALCUTTA
1909
1958
JUN 3
TO...
ALFRED RUSSEL WALLACE
WHO GAVE TO HIS BOOK ON NATURAL SELECTION
THE TITLE ‘DARWINISM’, THIS COLLECTION
OF ADDRESSES ON DARWIN AND THE
m: 7 ‘ORIGIN’ IS AFFECTIONATELY
. DEDICATED
m
<
i i
PREFACE
Durine the fourteen months preceding the date
on which this volume is issued I have devoted all
available time to work connected with the three
inspiring anniversaries of July 1, 1908, Feb. 12,
1909, and Nov. 24, 1909. With all diffidence I
have chosen the date which closes this period of
work, as the day of publication. It may help in
some small degree to keep in remembrance the
birthday of a mighty epoch in the history of
thought. 7
The first Section of this book attempts to give
a brief account of the history which led up to and
followed the publication of the theory of Natural
Selection and the Origin of Species. Darwin's
sure scientific insight, and his views on evolution
by mutation, briefly treated in this Section,
receive further consideration in Appendices A
and B. The confusion of thought threatened by
the unintentional but most unfortunate mis-
representation of de Vries’s term, ‘ fluctuating
variability,’ is pointed out in a footnote and
further considered in Appendix D. I have given
_ at the end of this Appendix a very brief account
of certain phases of thought, during the past
vi PREFACE >
half century, on the variations forming the
material out of which the steps of evolutionary
progress have been supposed to be built.
The influence of Darwin’s personality upon the
intellectual revolution of the past fifty years is
considered in the second Section. The wide-
spread misunderstanding of the changes which
Darwin describes in his own mind, and the
consequent injustice to scientific men generally,
and especially to Darwin himself, not only form
the subject of argument and protest in this
Section, but also occupy nearly all the brief third
Section, part of the seventh, and the whole of
Appendix C.
The unfortunate misinterpretations ern ed to
above require, for their complete and final refuta-
tion, the collection from Darwin’s correspondence
of a large number of passages bearing upon
health. These, placed together, may convey to
the hasty reader an entirely wrong impression of
Darwin’s heroic spirit, and I therefore trust
that the words on p. 216 will be remembered
whenever such passages may be read.
In the fourth Section the relationship of Dar win
to the two ancient English Universities, and
especially to his own University of Cambridge, is
very briefly considered.
The fifth Section is concerned with one of the
first and still perhaps the most striking of the
PREFACE vii
interpretations that have sprung from the theory
of Natural Selection, The subject, ‘the Value of
Colour in the Struggle for Life,’ is treated histori-
cally. Darwin’s own hypotheses and discoveries
in this line, and his keen interest in the
hypotheses and discoveries of others are especially
considered here and also in part of the seventh
Section,
The sixth Section deals with Mimicry, the
most arresting of all the uses which colour may
subserve in the struggle for existence. It is
maintained that this complicated subject is best
approached by the study of North American
examples, and attention is directed to the number
of inspiring problems which await a thorough and
systematic attack by American naturalists,
Darwin’s hitherto unpublished letters to Mr.
Roland Trimen, F.R.S., form the subject of the
seventh Section. An interesting account of
Mr. Trimen’s first meeting with the illustrious
naturalist fifty years ago is also included. In
addition to the eighteen letters in Section VII,
four written by Darwin to other correspondents
are published in this volume—one in Section I,
two in Section V, and one in Section VI. I
desire to thank my friends for generously
lending me these twenty-two deeply interesting
letters, and Mr, Francis Darwin for kindly
permitting their publication.
viii PREFACE ~
The occasions on which the addresses here
printed were delivered are described in an
introductory note at the beginning of each
Section. Three out of the seven Sections of
this volume, viz. I, IV, and V, have already
appeared ; four are now published for the first
time.
I have especial reasons for being grateful to my
American friends for permission to reprint the
address contained in the first Section. The Publi-
cation Committee of the American Association
for the Advancement of Science did me the
honour of choosing the title of my address as
the title of the complete work—Fifty Years of
' Darwinism,—containing the eleven centennial
addresses, in honour of Charles Darwin, delivered
on Jan. 1, 1909. The publishers who owned the
copyright were very doubtful about the success of
the work—unnecessarily as it happened, for I
understand that a second edition is already being
prepared. In spite of considerations which
- seemed at the time to be weighty, both Com-
mittee and Publishers at once granted me the
most free and cordial permission to reprint the
address in the present work.
The Syndics of the Cambridge University Press
generously allowed the publication, on Nov. 24, of
Section V, which had appeared as Essay XV of
Darwin and Modern Science only eight months
ra’
Bh eh es
ey
=
PREFACE ix
earlier, the Preface being dated March 20, 1909.
I also desire to acknowledge the kind permission
to publish Section IV from Darwin Celebration,
Cambridge, June, 1909. Speeches delivered at the
Banquet held on June 28rd, printed for private cir-
culation by Sir George Darwin and Mr. Francis
Darwin.
In these later years the multitudes seem, for
the moment at least, to recognize a prophet in
every reed shaken with the wind. It would be
interesting to know the number of forgotten
works, of works soon to be forgotten, of works
dead before they were born, which have been
proclaimed as ‘the most important contribu-
tion to biological thought since the appearance
of the Origin of Species’. I would that the
multitudes were not mere followers of the fleeting
scientific fashions of a day, but that they were
right in their intuitions: I would that Newtons
and Darwins might arise in every generation.
I cannot admit that the inability to see them
on every side is merely the natural consequence
of a cynical and pessimistic spirit. I am fully
aware of the intellectual rigidity that is so prone
to develop with the passing years; but to know
the danger is in some measure to be armed against
it. I have steadily endeavoured to keep my
mind elastic and flexible ; and, in my own special
x PREFACE —
line of work, have again and again abandoned
the most dearly loved hypothesis when a new
interpretation was seen to be more consistent with
an ever-growing store of facts. And I submit
that it is even more difficult to keep an open
mind in the pursuit of a special line of research
than in the consideration of the broadest and
most far-reaching problems which confront the
human intellect.
Although the splendidly thorough work of the
present day must rightly compel the warmest
admiration, there are valid reasons why we should
direct a searching and critical gaze upon the pro-
clamation of each enthusiastic specialist that the
foundations of organic evolution are wholly sur-
rounded by the boundaries of his own field of
inquiry. Organic evolution, to be understood,
must be studied not in the light of one special
line of work, but of all. This was the great secret
of Darwin’s unique power in dealing with it, He
could see the subject from all sides. And an
ample measure of Darwin’s strength was possessed
by his great comrades of half a century ago. How
we long for a little of the sure insight and com-
prehensive vision of Asa Gray as we read the
address of his distinguished living representative,
Professor J. M. Coulter, who considers that an
adaptive response to environment is destructive
of Natural Selection, and finds it hard to imagine
PREFACE xi
how Darwinism can account for the valuable
mechanical functions of lifeless structures.'' And
even more arresting is the contrast between
Darwin’s outlook on the world of life and that
of the eminent Dutch botanist who raised fresh
strains, or perhaps sorted over again old mixtures
of Evening Primroses, and straightway said to his
friends: ‘Go to, let us build us an exalted
theory of evolution based on the conception of
an inborn transforming force violently discharged
at regular intervals by every species of times past,
present, and to come.’ And the historic fate of
the too-ambitious builders of Babel is already
evident ; for, when Professor de Vries, Professor
Bateson, and Mr. R. C. Punnett: begin to talk of
variability in its commonest form, their language
is confounded, ‘that they may not understand
one another's speech.’ * And when we remember
that the two last-named authorities are the recog-
nized English exponents of the views of the first-
named, it will be realized that the confusion
which has resulted from the misunderstanding of
the words ‘acquired character’ and the word
‘Mimicry’ is as nothing to the confusion worse
confounded which is even now upon us. The
misunderstanding of de Vries by his exponents
does however help us to solve one mystery,—the
1 Fifty Years of Darwinism, New York (1909), 61-5. See also
the Quarterly Review (July, 1909), 7.
2 See 49, and Appendix D, 258.
xii PREFACE
extraordinary and,—as many naturalists think,—
the unwarrantable exaggeration of the importance
of the Dutch botanist’s contributions to evolution.
Omne ignotum pro magnifico. If de Vries had
indeed proved, as his exponents assert, that the
‘individual differences’ in which Darwin saw the
steps of evolutionary progress—the ‘individual
differences ’ whose behaviour in heredity is the life-
work of Francis Galton—that these are in fact non-
transmissible to offspring, then surely the great-
ness of him who demonstrated such a discovery to
the world might be justly measured by the depth
of the error into which his predecessors had fallen.
I need hardly say that de Vries makes no such
claim, but, on the contrary, shows us again and
again that hereditary transmission to offspring is
essential to his conception of ‘fluctuating varia-
bility ’.
For de Vries’s laborious and original investiga-
tions every one must feel the warmest admiration,
He and his friend Professor Hubrecht have
always been most anxious to emphasize their
conclusion that the Mutationstheorie is Darwinian,
and they are equally anxious to disown and dis-
credit any attempts to use it as a weapon against
Darwin. They have even fallen into the error of
maintaining that Darwin anticipated de Vries in
holding the main conclusion of the Mutationstheorie
-—the origin of species by the selection of large
PREFACE xiii
single variations,' It is with great reluctance that
I have protested against the unduly important posi-
tion which, as I believe, is assigned to de Vries’s
work and conclusions in the history of evolution.
The Darwinian of the present day holds an inter-
mediate position between the followers of Buffon
and Lamarck, and the Mutationists, with whom
the Mendelians are somewhat unnecessarily allied.
The disciple of the two first-named naturalists,
in these days calling himself an oecologist, main-
tains that organisms are the product of their
environment: the Mutationist holds that organ-
isms are subject to inborn transformation, and
that environment selects the fittest from among
a crowd of finished products. The Darwinian
believes that the finished product or species is
gradually built up by the environmental selection
of minute increments, holding that, among inborn
variations of all degrees of magnitude, the small
and not the large become the steps by which
evolution proceeds. He attempts to avoid, as
Darwin did, on the one hand the error of as-
eribing the species-forming forces wholly to
a creative environment, and, on the other, the
perhaps more dangerous error of ascribing them
wholly to creative internal tendencies.
' Both professors of course admit that Darwin also believed in
an evolution founded on the selection of ‘individual differences ’,
xiv PREFACE
The failure of the earlier attacks on the Origin
has been referred to in many pages of this book ;
but my chief object throughout has been to speak
of Darwinism and of Darwin himself. Hence
Mendelism, entirely unknown to the illustrious
naturalist, is on this occasion barely mentioned.'
The conception of evolution by mutation, on the
other hand, is shown to have been from the first
entirely familiar to Darwin, and entirely rejected
by him. In the Quarterly Review’ for July, 1909,
I have ‘endeavoured to set forth—necessarily
with brevity—the chief results of those modern
investigations which, after fifty years, are now
believed to be charged with menace for the
Darwin-Wallace hypothesis’; and I will con-
clude by quoting the final words of the article:
‘The inspiration of these investigations has at-
tracted a numerous band of enthusiastic and
devoted labourers, who have achieved and are
achieving results of the highest interest and im-
portance. No one of these, it is here maintained,
can be reasonably held to make good the’claims
of the modern opponent of natural selection and
evolution as conceived by Darwin. The only
fundamental changes in the doctrine given to us
1 See however the close of Appendix D Attention is directed
in Section VI to certain North American butterflies which appear
to afford a peculiarly favourable opportunity of testing the
working of Mendel’s law under natural conditions.
2 «The Centenary of Darwin: Darwin and his Modern Critics,’
1-38,
yt aes) Fae oe ‘
mt a a ee , 71 a¥a
era _ PREFACE xv
oe ol 1859 are those brought about by the
Bice rches and the thoughts of Weismann; and
c ‘these have given to the great theory which will
ever be associated with the names of the two
_ illustrious English. naturalists a position far higher
than that ever assigned to it by Darwin himself.’
EDWARD B. POULTON.
OxFoRD, ©
Nov. 24, 1909.
: 7
i-_
¥ -
*
.
7
-
yy
CONTENTS
I. Fiery Years or Darwinism (Baltimore, Jan. 1,
NOOO ce as em at ee Se
II. Tae Personauiry or Cuartes Darwin (Balti-
more, Jan. 1, 1909)
III. Tue Darwin Centenary at Oxrorp (Feb. 12,
1909)...
IV. Cuartes DARWIN AND THE UNIVERSITY OF CAM-
BRIDGE (Cambridge, June 23, 1909)
V. Tue VALUE or CoLouR IN THE STRUGGLE FoR LIFE
VI. Mrimicry 1n THE ButtTerFiies oF NortH AMERICA
(Baltimore, Dec. 31, 1908)
VII. Lerrers rrom Cuartes Darwin To Ro.anp
Tren (1863-71)
APPENDIX A. Cuartes Darwin AND THE Hypo-
THESIS OF MuLTIPLE ORIGINS
APPENDIX B. Darwin anv Evotvution sy Mv-
TATION .
APPENDIX C. Furtruer Proor tuHat ScrentiFic
WoRK WAS NECESSARY FOR DARWIN
APPENDIX D. De Variss’s ‘ Fiuctuarions’ HERE-
DITARY ACCORDING TO DE VRIES, NON-TRANS-
MISSIBLE ACCORDING TO BATESON AND
PuNNETT
INDEX
144
, 213)
rg
247
254
. 256
258
281
Se —E—EE———— ee
I
FIFTY YEARS OF DARWINISM
One of the centennial addresses in honour of Charles
Darwin, read before the American Association for the
Advancement of Science, Baltimore, Friday, January 1,
1909. Revised and extended.
On this historic occasion it is of special interest
to reflect for a few moments on the part played
by the New World in the origin and growth of
the great intellectual force which dominates the
past half-century. The central doctrine of evolu-
tion, quite apart from any explanation of it, was
first foreed upon Darwin’s mind by his South
American observations during the voyage of the
Beagle; and we may be sure that his experience
in this same country, teeming with innumerable
and varied forms of life, confirmed and deepened
his convictions as to the importance of adaptation
and thus prepared the way for Natural Selection.
Wallace, too, at first travelled in South America,
and only later in the parts of the Old World
tropics which stand next to South America in
richness.
Asa Gray in the New World represents
Sir Joseph Hooker in the Old, as regards the
help given to Darwin before the appearance of
B
2 FIFTY YEARS OF DARWINISM
the Origin; and in strenuous and most efficient
defence after its appearance, Chauncey Wright
similarly represents Henry Fawcett. Fritz
Miller not only actively defended Darwin, but
continually assisted him by the most admirable
and original observations carried out at his
Brazilian home. Turning to those who in some
important respects differed from Darwin, I do
not think a finer example of chivalrous con-
troversy can be found than that carried on
between him and Hyatt. The immense growth
of evolutionary teaching, in which John Fiske
played so important a part, although associated
with the name of Herbert Spencer, must not be
neglected on an occasion devoted to the memory
of Darwin.
Outside the conflict which raged round the
Origin, we find Dana the only naturalist who
at first supported Darwin in his views on the
persistence of ocean basins and continental areas,
and Alexander Agassiz, for many years the
principal defender of the Darwinian mors of
coral islands and atolls.
American Palaeontology, famed himoton the
world, has exercised a profound influence on
the growth and direction of evolutionary thought.
The scale and perfection of its splendid fossil
records have attracted the services of a large band
of the most eminent and successful labourers, of
whom I can only mention the leaders :—Leidy,
Cope, Marsh, Osborn, and Scott, in the Verte-
2 ia
AMERICA AND EVOLUTION 3
brata; Hall, Hyatt, and Walcott in the Inverte-
brata. The study of American. Palaeontology
was at first believed to support a Neo-Lamarckian
view of evolution, but this, as well as the hypo-
thesis of polyphyletic or multiple origins (see
Appendix A, p. 247), was undermined by the
teachings of Weismann. Difficulties for which
the Lamarckian theory had been invoked were
met by the hypothesis of Organic Selection, sug-
gested by Baldwin and Osborn, and in England
by Lloyd Morgan. Weismann’s contention that
inherent characters are alone transmissible by
heredity has also received strong support from
the immense body of Cytological, Mendelian, and
Mutationist work to which other addresses to be
delivered to-day will bear eloquent testimony.’
Finally, the flourishing school of American Psy-
chology, under the leadership of William James
and James Mark Baldwin, accepts, and in accept-
ing helps to confirm, the theory of Natural
Selection.
ERASMUS DARWIN AND LAMARCK
Professor Henry F. Osborn, in his interesting
work, From the Greeks to Darwin, concludes that
Lamarck was unaware of Erasmus Darwin’s Zoo-
nomia, and that the parallelism of thought is
a coincidence. The following passage from
* The addresses referred to are published in Fifty Years of
Darwinism, New York, Henry Holt and Company, 1909,
2 From the Greeks to Darwin, New York, 1894, 152-5. Professor
Osborn shows on p. 145 that Erasmus Darwin made use of the term
B2
4 FIFTY YEARS OF DARWINISM
a letter! written to Huxley, probably in 1859,
and published since the appearance of Professor
Osborn’s book, indicates that Charles Darwin
suspected the French naturalist of borrowing
from his grandfather :—
‘The history of error is quite unimportant, but it is curious
to observe how exactly and accurately my grandfather (in
Zoonomia, vol. i, p. 504, 1794) gives Lamarck’s theory. I
will quote one sentence. Speaking of birds’ beaks, he says:
‘All which seem to have been gradually produced during
many generations by the perpetual endeavour of the creatures
to supply the want of food, and to have been delivered to
their posterity with constant improvement of them for the
purposes required.” Lamarck published Hist. Zoolog. in 1809.
The Zoonomia was translated into many languages.’
A careful comparison of the French transla-
tion of the Zoonomia with Lamarck’s Philosophie
Zoologique and with a preliminary statement of
his views published in 1802, would probably
decide this interesting question.
THE INFLUENCE OF LYELL UPON CHARLES
DARWIN
The limits of space compel me to pass by the
youth of Charles Darwin, with the influence of
school, Edinburgh and Cambridge, including his
intimacy with Henslow—a friendship leading to
the voyage in the Beagle. We must also pass
by his earliest convictions on evolution, the
‘acquired’ in the sense of ‘acquired characters’; ‘changement
acquis’ is the form employed many years later by Lamarck.
1 More Letters of Charles Darwin. Edited by Francis Darwin and
A. C. Seward, London, 1903, i. 125. Hereafter quoted as More
Letters.
i I, ich
DARWIN’S DEBT TO LYELL 5
first note-book begun in 1837, the reading of
Malthus and discovery of Natural Selection in
October, 1838, the imperfect sketch of 1842, the
completed sketch of 1844.
It is necessary, however, to pause for a brief
consideration of the influence of Sir Charles Lyell.
Although the writings of the illustrious geologist
have always been looked upon as among the
chief of the forces brought to bear upon the mind
of Darwin, evidence derived from the later
volumes of correspondence justifies the belief
that the effect was even greater and more signi-
ficant than has been supposed.
Huxley has maintained with great force that
the way was paved for Darwin by Lyell’s Principles
of Geology far more thoroughly than by any other
work,
. consistent uniformitarianism postulates evolution
as much in the organic as in the inorganic world. The
origin of a new species by other than natural agencies would
be a vastly greater “ catastrophe” than any of those which
Lyell successfully eliminated from sober geological specula-
tion.’'
When the first volume of the Principles appeared
in 1880, Darwin was advised by Henslow to
obtain and study it, ‘but on no account to accept
the views therein advocated.’ Darwin took the
volume with him on the voyage, and a study of
the very first place at which the Beagle touched,
1 Life and Letters of Charles Darwin, edited by Francis Darwin,
London, 1887, ii. 190. Hereafter quoted as Life and Letters.
6 FIFTY YEARS OF DARWINISM
St. Jago, one of the Cape de Verde Islands,
showed him the infinite superiority of Lyell’s
teachings.!
He wrote in 1876: ‘The science of Geology is
enormously indebted to Lyell—more so, as I
believe, than to any other man who ever lived.’?
An even more remarkable tribute to his old
teacher is paid by Darwin in the following words
written to L. Horner, August 29, 1844 :—
‘T have lately been reading with care A. d’Orbigny’s work
on South America, and I cannot say how forcibly impressed
I am with the infinite superiority of the Lyellian school of
Geology over the continental. I always feel as if my books
came half out of Lyell’s brain, and that I never acknowledge
this sufficiently ; nor do I know how I can without saying
so in so many words—for I have always thought that the
great merit of the Principles was that it altered the whole
tone of one’s mind, and therefore that, when seeing a thing
never seen by Lyell, one yet saw it partially through his
eyes—it would have been in some respects better if I had
done this less... .’°
This letter was written not two months after
the date which marks the completion of the
finished sketch of 1844. On July 5, ‘Darwin
wrote the letter to his wife begging her, in the
event of his death, to arrange for the publication
of the account he had just prepared. At this
psychological moment in his career he wrote of
the influence received from Lyell, and we are
naturally led to observe how essentially Lyellian
1 Life and Letters, i. 62, 72, 73. 21. ©. 72.
8 More Letters, ii. 117.
LYELL’S DEBT TO DARWIN 7
are the three lines of argument—two based on
geographical distribution, one on the relation
between the living and the dead—which first
led Darwin toward a belief in evolution. The
thoughts which shook the world arose in a mind
whose whole tone had been altered by Lyell’s
teachings. Inasmuch as the founder of modern
geology received his first inspiration from
Buckland, Oxford may claim some share in
moulding the mind of Darwin.'
It is deeply interesting to set beside the
evidence of Darwin’s debt to Lyell the words in
which Lyell gives us some conception of what
Darwin’s friendship—even in its early days—
meant for him. Not long after Darwin’s mar-
riage (Jan. 29, 1839), when he and his wife
were contemplating leaving London for the
country, Lyell wrote :—
‘I cannot tell you how often since your long illness I
have missed the friendly intercourse which we had so
frequently before, and on which I built more than ever after
your marriage. It will not happen easily that twice in
one’s life, even in the large world of London, a congenial
soul so occupied with precisely the same pursuits and with
an independence enabling him to pursue them will fall so
nearly in my way, and to have had it snatched from me
with the prospect of your residence somewhat far off is
a privation I feel to be a very great one.’?
? See also pp. 86, 87. :
* July ?, 18419. More Letters, i. 31. Darwin left London for
Down on Sept. 14, 1842.
8 FIFTY YEARS OF DARWINISM
‘COMING EVENTS CAST THEIR SHADOWS
BEFORE’
The characteristic feature in which Natural
Selection differs from every other attempt to
solve the problem of evolution is the account
taken of the struggle for existence, and the réle
assigned to it. Professor Osborn! refers to the
keen appreciation of this struggle in Tennyson’s
noble poem, In Memoriam, the dedication of which
is dated 1849, ten years before the Origin. The
poet is disquieted by :—
‘Nature red in tooth and claw
With -TAvane? A oe ts a ee ee ‘
and by
‘, .. finding that of fifty seeds
She often brings but one to bear.’
It is interesting to note that the obvious under-
statement of this last passage is corrected in the
author’s notes published by his son a few years
ago. In these we find ‘for fifty, read myriad’.
The poignant sense of the waste of individual
lives is brought into close relation in the poem
with the destruction of the type or species :—
‘So careful of the type she seems,
So careless of the single life ;’
66 So careful of the ‘type ? ” but no,
From scarped cliff and quarried stone
She cries “ A thousand types are gone:
+ ed
I care for nothing, all shall go”.
' From the Greeks to Darwin, New York, 1894, 141.
TENNYSON AND THE ‘ORIGIN’ 9
In this association between the struggle for
existence waged by individuals and the extinction
and succession of species we seem to approach
the central idea of Darwin and Wallace. A few
years before Tennyson’s death I asked Dr. Grove,
of Newport, in the Isle of Wight, if he would
point out the parallelism, so far as it existed, to his
illustrious patient, hoping that some light might
be thrown on the source of the inspiration. Nor
was I disappointed. ‘Stay,’ said the aged poet
when Dr. Grove had spoken, ‘In Memoriam was
published long before the Origin of Species.’ ‘Oh!
then you are the man,’ replied the doctor. ‘ Yes,
I am the man.’ There was silence for a time;
then Tennyson said: ‘I don’t want you to go
away with a wrong impression. The fact is that
long before Darwin’s work appeared these ideas
were known and talked about.’ From this deeply
interesting conversation I think it is probable
that, perhaps through mutual friends, some echo
of Darwin’s researches and thoughts had reached
the great author of In Memoriam.}
The light which has been recently thrown?
upon Philip Gosse’s remarkable book, Omphalos,
indicates that its appearance in 1858 was
connected with the thoughts that were to arouse
? In a valuable letter on Darwin and Tennyson in The Spectator
for Aug. 7, 1909 (pp. 197, 198), the Rev. F. St. John Thackeray
points out that the poet was from his youth deeply interested in
evolution, and that in 1837 he studied Lyell’s Principles. It is
shown above, however, that the appreciation of the struggle for
existence is an essentially Darwinian idea.
2 In Father and Son, London, 1907.
10 FIFTY YEARS OF DARWINISM
the world in the following year. The author of
Omphalos was a keen and enthusiastic naturalist
held fast in the grip of the narrowest of religious
creeds. We learn with great interest that he
and others were by Lyell’s advice prepared
beforehand for the central thoughts of the Origin.
To the new teaching all the naturalist side of his
nature responded, but from it the religious side
recoiled. Religion conquered in the strife, but
the naturalist found comfort in the perfectly
logical conclusion that : —
‘any breach in the circular course of nature could be con-
ceived only on the supposition that the object created bore
false witness to past processes, which had never taken place.’ ’
Thus the divergence between the literal inter-
pretation of Scripture and the conclusions of both
geologist and evolutionist were for this remarkable
man reconciled by the conviction :—
‘that there had been no gradual modification of the
surface of the earth, or slow development of organic forms,
but that when the catastrophic act of creation took place,
the world presented, instantly, the structural appearance of
a planet on which life had long existed.’?
Philip Gosse could not but believe that the
thoughts which had brought so much comfort
to himself would prove a blessing to others also.
He offered Omphalos ‘with a glowing gesture,
to atheists and Christians alike. . . . But,
alas! atheists and Christians alike looked at it and
laughed, and threw it away’. Charles Kingsley
1 Le., 120, 121. ? 1. c., 120. * Le. 122.
THE CREATION OF FALSE WITNESS 11
expressed the objection felt by the Christian when
he wrote that he could not ‘ believe that God had ,
written on the rocks one enormous and super-
fluous lie’.
About twenty years ago I was present when
precisely the same conclusion was advanced by
a high dignitary of the English Church. He
argued that even if the history of the Universe
were carried back to a single element such as
hydrogen, the human mind would remain unsatis-
fied and would inquire whence the hydrogen came,
and that any and every underlying form of mat-
ter must leave the inexorable question ‘ whence?’
still unanswered. Therefore if in the end the
question must be given up, we may as well,
he argued, admit the mystery of creation in the
later stages as in the earlier. Thus he arrived at
the belief in a world formed instantaneously,
ready-made and complete, with its fossils, marks
of denudation, and evidences of evolution—a going
concern. Aubrey Moore, the clergyman who
more than any other man was responsible for
breaking down the antagonism towards evolution
then widely felt in the English Church, replied
very much as Kingsley had done, that he was
unwilling to believe that the Creator had de-
liberately cheated the intellectual powers He had
1 Tbid. It is possible that Darwin was referring to Omphalos
when he wrote, Sept. 2, 1859, to Lyell, ‘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.’
Life and Letters, ii. 165.
12 FIFTY YEARS OF DARWINISM
made. I may add that, inasmuch as science con-
sists in the attempt to carry down causation as
far as possible, it is above all the scientific side of
the human intellect that is outraged—no weaker
term can be used—by this more modern develop-
ment of the argument of Omphalos.
THE PUBLICATION OF THE DARWIN-WALLACE
ESSAY
In May, 1856, Darwin, urged by Lyell, began to
prepare for publication. He had determined to
present his conclusions in a volume, for he was
unwilling to place any responsibility for his
opinions on the Council of a Scientific Society.
On this point, he was, as he told Sir Joseph
Hooker, in the only fit state for asking advice,
namely, with his mind firmly made up: ‘then
. . . good advice was very comfortable, and it was
easy to reject bad advice.’' The work was con-
tinued steadily until June 18, 1858, when Wal-
lace’s letter and essay arrived from Ternate. As
a result of the anniversary held in London on
_ July 1, 1908, new light has been thrown, upon
the circumstances under which the joint essay
was published fifty years before. .
In consequence of the death of the eminent
botanist, Robert Brown, Vice-President and Ex-
President of the Linnean Society, the last meeting
of the summer session, called for June 17, was
adjourned. The bye-laws required that the
1 Life and Letters, ii. 70. See also 68, 69, 71.
al
ated
THE EVENTS OF JULY 1, 1858 18
vacancy on the Council should be filled up within
three months, and a special meeting was called
for July 1 for this purpose. Darwin received
Wallace's essay on June 18, too late for the
summer meetings of the Society, but in good
time for Lyell and Hooker to present it to the
special meeting. Hence, as Sir Joseph Hooker
said on July 1, 1908, the death of Robert Brown
caused the theory of Natural Selection to be
‘given to the world at least four months earlier
than would otherwise have been the case’. Sir
Joseph Hooker also informed us that from
June 18, up to the evening of July 1, when
he met Sir Charles Lyell at the Society, all the
intercourse with Darwin and with each other was
conducted by letter, and that no fourth person
was admitted into their confidence. The joint
essay was read by the Secretary of the Society.
Darwin was not present, but both Lyell and
Hooker ‘said a few words to emphasise the
importance of the subject’! Among those who
were present were Oliver, Fitton, Carpenter,
Henfrey, Burchell, and Bentham,’ who was elected
* Darwin-Wallace Celebration of the Linnean Society of London
(1908), 14, 15.
* July 1, 1858, was an important date in the life of the great
botanist George Bentham. He had himself prepared for that very
meeting a long paper illustrating what he believed to be the
fixity of species. ‘Most fortunately my paper had to give way to
Mr. Darwin’s, and when once that was read, I felt bound to defer
mine for reconsideration ; I is 9 to entertain doubts on the
subject, and on the appearance of the “ Origin of Species’, I was
forced, however reluctantly, to give up my long-cherished con-
victions, the results of much labour and study, and I cancelled all
that part of my paper which urged original fixity.’ Life and
Leiters, ii, 294. See also the Quarterly Review (July, 1909), 6.
14 FIFTY YEARS OF DARWINISM
on the Council and nominated as Vice-President
in place of Robert Brown.
I cannot resist the temptation to reprint from
the memorial volume issued by the Linnean
Society of London some passages in the address
which A. R. Wallace felt constrained to deliver
on July 1, 1908, protesting against the too great
credit which he believed had been assigned to
himself. After describing Darwin’s discovery of
Natural Selection and the twenty years devoted
to confirmation and patient research, Wallace
continued :—
‘How different from this long study and preparation—
this philosophic caution—this determination not to make
known his fruitful conception till he could back it up by
overwhelming proofs—was my own conduct. The idea
came to me, as it had come to Darwin, in a sudden flash of
insight: it was thought out in a few hours—was written
down with such a sketch of its various applications and
developments as occurred to me at the moment,—then
copied on thin letter-paper and sent off to Darwin—all with-
in one week. J was then (as often since) the “ young man
ina hurry”: he, the painstaking and patient student, seek-
ing ever the full demonstration of the truth that he had
discovered, rather than to achieve immediate personal
fame.
‘Such being the actual facts of the case, I should have
had no cause for complaint if the respective shares of
Darwin and myself in regard to the elucidation of nature’s
method of organic development had been thenceforth
estimated as being, roughly, proportional to the time we had
each bestowed upon it when it was thus first given to
the world—that is to say, as 20 years is to one week.
For, he had already made it his own. If the persuasion of
his friends had prevailed with him, and he had published
ee
WALLACE’S WORDS ON JULY 1, 1908 15
’
his theory, after 10 years’—15 years’—or even 18 years
elaboration of it—Z should have had no part in it what-
ever, and he would have been at once recognised, and
should be ever recognised, as the sole and undisputed dis-
coverer and patient investigator of the great law of ‘“‘ Natural
Selection ” in all its far-reaching consequences.
‘It was really a singular piece of good luck that gave
me any share whatever in the discovery. . . it was only
Darwin’s extreme desire to perfect his work that allowed me
to come in, as a very bad second, in the truly Olympian race in
which all philosophical biologists, from Buffon and Erasmus
Darwin to Richard Owen and Robert Chambers, were more
or less actively engaged.’ !
ECHOES OF THE STORM
It is impossible to do more than refer briefly
to the storm of opposition with which the Origin
was at first received. The reviewer in the
Athenaeum for Nov. 19, 1859, left the author
‘to the mercies of the Divinity Hall, the Col-
lege, the Lecture Room, and the Museum ’.?
Dr. Whewell for some years refused to allow
a copy of the Origin to be placed in the library
of Trinity College, Cambridge.* My predecessor,
Professor J. O. Westwood, proposed to the last
Oxford University Commission the permanent
endowment of a lecturer to combat the errors
of Darwinism. ‘ Lyell had difficulty in prevent-
ing [Sir William] Dawson reviewing the Origin
on hearsay, without having looked at it. No
spirit of fairness can be expected from so biassed
' Darwin-Wallace Celebration of the Linnean Society of London
(1908), 6, 7.
® Life and Letters, ii, 228 n. 8 Tbid., 261 ».
16 FIFTY YEARS OF DARWINISM
a judge.’ * . And even when naturalists began to
be shaken by the force of Darwin’s reasoning,
they were often afraid to own it. Thus Darwin
wrote to H. Fawcett, on Sept. 18, 1861 :—
‘Many are so fearful of speaking out. A German
naturalist came here the other day; and he tells me that
there are many in Germany on our side, but that all seem
fearful of speaking out, and waiting for some one to speak,
and then many will follow. The naturalists seem as timid
as young ladies should be, about their scientific reputation.’ ?
Among the commonest criticisms in the early
days, and one that Darwin felt acutely,* was the
assertion that he had deserted the true method of
scientific investigation. One of the best exam-
ples of this is to be found in the letter of Darwin’s
old teacher in geology, Adam Sedgwick :—
‘You have deserted—after a start in that tram-road of all
solid physical truth—the true method of induction, and
started us in machinery as wild, I think, as Bishop Wilkins’s
locomotive that was to sail with us to the moon.’ 4
This ill-aimed criticism was soon set to rest by
Henry Faweett’s article in Macmillan’s Magazine
1 From a letter written by Darwin to Hooker, Nov. 4, 1862.
More Letters, i. 468.
2 More Letters, i. 196.
8 See Darwin’s letter to Henslow, May 8, 1860. More Letters, i.
149, 150.
* Life and Letters, ii. 248. Sedgwick’s letter is dated Dec. 24,
1859, but the editors of More Letters (i. 150 n.) express the opinion
that it must have been written in November at latest. See also
the Quarterly Review for July, 1860. Sedgwick’s review in the
Spectator, Mar. 24, 1860, contains the following passage:
. I cannot conclude without expressing my detestation of the
theory, because of its unflinching materialism ;—because it has
deserted the inductive track, the only track that ‘leads to physical
truth ;—because it utterly repudiates final causes, and thereby
indicates a demoralised understanding on the part of its advocates.
Quoted in Life and Letters, ii. 298.
SUPPORT BY MILL AND FAWCETT 17
in 1860, and by a paper read before the British
Association by the same author in 1861. _Refer-
ring to this defence Fawcett wrote to Darwin,
July 16, 1861 :—
‘I was particularly anxious to point out that the method
of investigation pursued was in every respect philosophically
correct. I was spending an evening last week with my
friend Mr. John Stuart Mill, and I am sure you will be
pleased to hear from such an authority that he considers
that your reasoning throughout is in the most exact accord-
ance with the strict principles of logic. He also says the
method of investigation you have followed is the only one
proper to such a subject.
‘It is easy for an antagonistic reviewer, when he finds it
difficult to answer your arguments, to attempt to dispose of
the whole matter by uttering some such commonplace as
“This is not a Baconian induction”. ...
‘ As far as I am personally concerned, I am sure I ought
to be grateful to you, for since my accident nothing has
given me so much pleasure as the perusal of your book.
Such studies are now a great resource to me.’*
To this Darwin replied :—
‘You could not possibly have told me anything which
would have given me more. satisfaction than what you say
about Mr. Mill’s opinion. Until your review appeared I
began to think that perhaps I did not understand at all how
to reason scientifically.’ *
In the general truth of his theory Darwin felt
an entire confidence born of the long years of
pondering over difficulties throughout the whole
realm of natural history. And it was the con-
sciousness that a secure and undisturbed belief
lay behind the fair and cautious statements of the
1 More Letters, i. 189, 190. 2 Tbid., 189.
©
18 FIFTY YEARS OF DARWINISM
Origin that was so intensely irritating to men
whose antagonism was based on religious con-
viction. Thus in Sedgwick’s letter, from which
I have already quoted, we read :—
‘* Lastly, then, I greatly dislike the concluding chapter—
not as a summary, for in that light it appears good—but
I dislike it from the tone of triumphant confidence in which
you appeal to the rising generation . .. and prophecy of
things not yet in the womb of time, nor (if we are to trust
the accumulated experience of human sense and the
inferences of its logic) ever likely to be found anywhere but
in the fertile womb of man’s imagination.’*
THE MATURITY OF THE ORIGIN CONTRASTED
WITH THE CRUDITY OF RIVAL
INTERPRETATIONS
It is remarkable to contrast the maturity, the
balance, the judgement, with which Darwin put
forward his views, with the rash and haphazard
objections and rival suggestions advanced by
critics. It is doubtful whether so striking a con-
trast is to be found in the history of science—
on the one side, twenty years of thought and
investigation pursued by the greatest of natura-
lists; on the other, off-hand impressions upon
a most complex problem hastily studied and
usually very imperfectly understood: It is not
to be wondered at that Darwin found the early
criticisms so entirely worthless. The following
extract from an interesting letter to John Scott,
1 Life and Letters, ii. 250.
AV
RASHNESS OF RIVAL HYPOTHESES 19
written on Dec, 3, 1862?, shows how well aware
he was of difficulties unnoticed by critics :—
‘ You speak of difficulties on Natural Selection: there are
indeed plenty ; if ever you have spare time (which is not
likely, as I am sure you must be a hard worker) I should be very
glad to hear difficulties from one who has observed so much
as you have. The majority of criticisms on the Origin are,
in my opinion, not worth the paper they are printed on.’!
From the very first the most extraordinarily
crude and ill-considered suggestions were put for-
ward by those who were unable to recognize the
value of the theory of Natural Selection. A good
example is to be found in Andrew Murray’s
principle of sexual selection based on contrast :—
‘It is trite to a proverb, that tall men marry little women
... aman of genius marries a fool... and we are told that
this is the result of the charm of contrast, or of qualities
admired in others because we do not possess them. I do
not so explain it. I imagine it is the effort cf nature to
preserve the typical medium of the race.’?
Even in these later years the wildest imagin-
ings may be put forward in all seriousness as the
interpretation of the world of living organisms.
Thus in Beccari’s interesting work on Borneo,*
the author compares the infancy and growth of
the organic world with the development and
education of an individual. In youth the indi-
vidual learns easily, being unimpeded by the
1 More Letters, ii, 311.
2 Life and Letters, ii. 261. The original paper is to be found
in the Proc. R. Soc. Edin., 1860.
8 Wanderings in the Great Forests of Borneo, 209-16, English
translation, London, 1904.
C2
20 FIFTY YEARS OF DARWINISM
force of habits, while ‘with age heredity acts
more strongly, instincts prevail, and adaptation
to new conditions of existence and to new ideas
become more difficult ; in a word, it is much less
easy to combat hereditary tendencies’, Similarly,
in the state of maturity now reached by the
organic world, Beccari believes that the power of
adaptation is wellnigh non-existent. Heredity,
through long accumulation in the course of endless
generations, has become so powerful that species
are now stereotyped and cannot undergo advan-
tageous changes. For the same reason, he con-
siders, acquired characters cannot now be trans-
mitted to offspring. Beccari imagines that
everything was different in early ages, when, as
he supposes, life was young and heredity weak,
In this assumed ‘ Plasmatic Epoch’ the environ-
ment acted strongly upon organisms, evoking the
responsive changes which have now been ren-
dered fixed and immovable by heredity.
Even the hypothesis proposed as a substitute
for Natural Selection by so distinguished a botanist
as Carl Nigeli turns out to be most unsatisfactory
the moment it is examined. The idea of evolution
under the compulsion of an internal force residing
in the idioplasm is in essence but little removed
from special creation. On the subject of Niigeli’s
criticisms Darwin wrote, Aug. 10, 1869, to Lord
Farrer :—
‘It is to me delightful to see what appears a mere morpho-
logical character found to be of use. It pleases me the more
DARWIN'S DEBT TO HOOKER 21
as Carl Niageli has lately been pitching into me on this head.
Hooker, with whom I discussed the subject, maintained that
uses would be found for lots more structures, and cheered
me by throwing my own orchids into my teeth.’ *
‘3 DARWIN’S GREATEST FRIENDS IN THE TIME
OF STRESS
It is interesting to put side by side passages
from two letters? written by Darwin to Hooker,
one in 1845 at the beginning of their friendship,
the other thirty-six years later, a few months
before Darwin’s death. The first shows the
instant growth of their friendship: ‘Farewell !
What a good thing is community of tastes! I
feel as if I had known you for fifty years.
Adios.’ |
The second letter expresses at the end of
Darwin’s. life the same feelings which find
utterance ever and again throughout the long
years of his friendship (see pp. 66, 67).
‘ Your letter has cheered me, and the world does not look
a quarter so black this-morning as it did when I wrote
before. Your friendly words are worth their weight in
gold.’
It was to Hooker that Darwin first confided,
Jan. 11, 1844, his belief in evolution, but did not
at the time, even to him, give any account of
natural selection :— |
‘At last gleams of light have come, and I am almost
convinced (quite contrary to the opinion I started with) that
1 More Letters, ii. 380.
* Ibid., i. 39. The passages here quoted are placed side by side
by the editors of this work.
wy
22 FIFTY YEARS OF DARWINISM
species are not (it is like confessing a murder) immutable. . ..
I think I have found out (here’s presumption !) the simple
way by which species become exquisitely adapted to various
ends. You will now groan, and think to yourself, ‘on
what a man have I been wasting my time and writing to.”
I should, five years ago, have thought so. ..”}
Elaborate investigations of all kinds during the
long years which led up to the central work of
Darwin’s life were discussed in detail with the
greatest of his friends, and it was an inestimable
advantage that the ideas of the Origin were thus
searchingly tried beforehand by so critical and,
in the best sense, sceptical a mind as Hooker’s—
‘you terrible worrier of poor theorists!’? as
Darwin called him. Again in 1868 :— |
‘I have got your photograph over my chimney-piece, and
like it much; but you look down so sharp on me that I
shall never be bold enough to wriggle myself out of any
contradiction.’ ®
The friendship with Asa Gray began with a
meeting at Kew some years before the publication
of Natural Selection. Darwin soon began to ask >
for help in the work which was ultimately to
- appear as the Origin. The following letter to
Hooker, June 10, 1855, shows what he thought of
the great American botanist :—
‘I have written him a very long letter, telling him some of
1 Life and Letters, ii. 23, 24. See also on p. 32 the letter, dated
Oct. 12, [1845], in which Darwin confided his belief ‘that species
are mutable’ tothe Rev. L. Jenyns (Blomefield). The passage
from a letter dated Feb. 14, 1845, to the same correspondent,
quoted on p. 42 n. 1, suggests that the communication of Oct. 12
was written in 1844 and not 1845,
? Feb. 28, [1858]. More Letters, i. 105.
5 More Letters, il. 376, 377.
DARWIN’S DEBT TO ASA GRAY 28
the points about which I should feel curious. But on my
life it is sublimely ridiculous, my making suggestions to
such a man.’
The friendship ripened very quickly, so that on
July 20, 1856, Darwin gave Asa Gray an account
of his views on evolution,? and on Sept. 5 of
the following year, a tolerably full description of
Natural Selection.* From this last letter Darwin
chose the extracts which formed part of his
section of the joint essay published July 1, 1858.
Asa Gray's opinion on first reading the Origin
was expressed not to Darwin but to Hooker in a
letter written Jan. 5, 1860 :—
‘It is done in a masterly manner. It might well have
taken twenty years to produce it. It.is crammed full of
most interesting matter—thoroughly digested—well ex-
pressed—close, cogent, and taken as a system it makes out
a better case than I had supposed possible. .. .’
After referring to Agassiz’s unfavourable
opinion of the book he continues: ‘Tell Darwin
all this. I will write to him when I get a chance.
As I have promised, he and you shall have
fair-play here. ...* <A little later, when on
Jan. 23 he wrote to Darwin himself, Asa
Gray concluded: ‘I am free to say that I never
learnt so much from one book as I have from
yours. There remain a thousand things I long
to say about it.’ ®
' More Letters, i. 418. Asa Gray's generous reply appears on
p. 421.
* Life and Letters, ii. 78. 3 Tbid., 120-5.
* Ibid., 268. 5 Ibid., 272.
ae
a5
=
24 FIFTY YEARS OF DARWINISM
It is impossible to do justice on the present
occasion to the numerous letters in which Darwin
expressed his gratitude for the splendid manner
in which Asa Gray kept his word and fought ‘like
a hero in defence’! At a time when few
naturalists were able to understand the drift of
Darwin’s argument, the acute and penetrating
mind of Asa Gray had in a moment mastered
every detail. Thus Darwin wrote on July 22, 1860,
concerning the article in the Proceedings of the
American Academy for April 10 :—
‘,. . I cannot resist expressing my sincere admiration for
your most clear powers of reasoning. As Hooker lately said
in a note to me, you are more than any one else the
thorough master of the subject. I declare that you know
my book as well as I do myself; and bring to the question
new lines of illustration and argument in a manner which
excites my astonishment and almost my envy!... Every
single word seems weighed carefully, and tells like a
32-pound shot.’ ?
Some weeks later, on Sept. 26, 1860, Darwin
again expressed the same admiration, and
stated that Asa Gray understood him more
perfectly than any other friend :—
‘, . « you never touch the subject without making it
clearer. I look at it as even more extraordinary that you
never say a word or use an epithet which does not express
fully my meaning. Now Lyell, Hooker, and others, who
perfectly understand my book, yet sometimes use expressions
to which I demur.’ *
' Life and Letters, ii, 310. ‘ae * Tbid., 326.
Ibid., 344, 345.
DARWIN’S DEBT TO HUXLEY 25
Darwin also sent! Asa Gray’s defence of the
Origin to Sir Charles Lyell, whom he was
extremely anxious to convince of the truth of
evolution. Asa Gray’s religious convictions
prevented the full acceptance of Natural Selection.
He was ever inclined to believe in the Providen-
tial guidance of the stream of variation. He also
apparently differed from Darwin in the extent to
which he was inclined to interpret instincts as
inherited habits.’
The same close intimacy and mutual help begun
in the preparation of the Origin was continued in
Darwin’s later botanical works. Thus Darwin
owed his Climbing Plants to the study of a paper
by Asa Gray, and he dedicated his Forms of
Flowers to the American botanist ‘as a small
tribute of respect and affection’, Concerning
some of the researches which afterwards appeared
in this book, Darwin wrote :— |
‘I care more for your and Hooker’s opinion than for that
of all the rest of the world, and for Lyell’s on geological
points.’ *
Another great name, that of Huxley, is
especially associated in our minds with the
defeat of those who would have denied that the
subject was a proper one for scientific investiga-
tion. In the strenuous and memorable years
that followed the appearance of the Origin, the
mighty warrior stands out as the man to whom
1 More Letters, i. 169. ed ee Life and Letters, iii. 170.
id., 300.
26 FIFTY YEARS OF DARWINISM
more than to any other we owe the gift of free
speech and free opinion in science,—the man so
admirably described by Sir Ray Lankester at
the Linnean Celebration as ‘ the great and beloved
teacher, the unequalled orator, the brilliant
essayist, the unconquerable champion and literary
swordsman—Thomas Henry Huxley’.!
Comparing the friendships to which Darwin
owed so much, Lyell was at first the teacher but
finally the pupil,—unwilling and unconvinced at
the outset, in the end convinced although still
unwilling ; Hooker in England and Asa Gray in
America were the two intimate friends on whom
Darwin chiefly depended for help in writing the
Origin, and for support to its arguments ; Huxley
was the great general in the field where religious
convictions, expressed or unexpressed, were the
foundation of a fierce and bitter antagonism.
THE ATTACKS OF RICHARD OWEN AND
ST. GEORGE MIVART
An unnecessary bitterness was imported into
the early controversies in England, because of the
personality of the scientific leaders in the attacks
on the Origin. Of these the chief was the great
comparative anatomist, Sir Richard Owen. In
spite of his leading scientific position, this
remarkable man withdrew from contact with his
brother zoologists, living in a self-imposed _isola-
1 Darwin-Wallace Celebration of the Linnean Society of London
(1908), 29. See also pp. 66-8 of the present work,
ia on she
vy *
THE ATTACKS OF OWEN 27
tion which tended towards envy and bitterness.
The same unavailing detachment had been
carried much further by the great naturalist
W. J. Burchell, who, as from a watch-tower,
looked upon the world he strove to avoid with an
absorbed and jealous interest. Prof. J. M. Baldwin -
has shown how inevitable and inexorable is the
grip of the social environment: the more we
attempt to evade it, the more firmly we seem to
be held in its grasp.
In the first years of the struggle, Owen’s bitter
antagonism made itself felt in the part he took as
‘crammer’ to the Bishop of Oxford, and in his
anonymous article in the Edinburgh Review for
April, 1860. But Owen could not bear to remain
apart from the stream of thought when there was
no doubt about the way it was flowing, so that in
a few years he was maintaining some of the chief
conclusions of the Origin, although retracting
nothing, but rather keeping up a bitter attack
upon Darwin. This treatment received from one
who was all affability when they met,' was natu-
rally resented by Darwin, whose feelings on the
subject are expressed in the following passage
from a letter to Asa Gray, July 23, 1862.
‘ By the way, one of my chief enemies (the sole one who
has annoyed me), namely Owen, I hear has been lecturing on
birds; and admits that all have descended from one, and
advances as his own idea that the oceanic wingless birds
1 «Mrs. Carlyle said that Owen’s sweetness always reminded her
of sugar of lead.’ Life and Letters of T. H. Huxley, London, ii. 167.
28 FIFTY YEARS OF DARWINISM
have lost their wings by gradual disuse. He never alludes
to me, or only with bitter sneers, and coupled with Buffon
and the Vestiges.’!
In the historical sketch added to the later
editions of the Origin, Owen is the only writer
who is severely dealt with. In this introductory
section Darwin said that he was unable to decide
whether Owen did or did not claim to have
originated the theory of Natural Selection.?
If Owen had withdrawn from his former
attitude of antagonism, as did Lyell, he would be
entitled to the same honourable place in the
memory of future generations. As it is, we must
regret that he did not keep up the struggle to the
1 More Letters, i. 203.
2 Origin of Species, 6th Ed., xviii. See also the writer's article
in the Quarterly Review for July, 1909, 4-6. The following remark-
able episode, which I owe to the kindness of my friend Mr. Roland
Trimen, F.R.S., is quoted from p. 5 :—
‘At Down, about the end of the year 1867, when conversing
with Mr. Darwin about the already steadily increasing acceptance
of the “Origin” among thinking naturalists, in contrast to the
active hostility it encountered on and long after its first appearance
only eight years before, I referred to the heavy artillery brought to
bear against it in the “Quarterly” and ‘‘ Edinburgh ” Reviews,
besides the host of other discharges from arms of minor calibre.
Mr. Darwin asked me if I knew who wrote the ‘‘ Edinburgh ” article,
and on my replying that I did not, but that I had heard Owen’s name
suggested amongst others, he said, “‘ Owen was the man.” I ven-
tured to enquire whether he came to this conclusion from other
evidence than that afforded by the style, tone, etc., of the article
itself; and he answered, “The internal evidence made me almost
sure that only Owen could have written it ; but when I taxed him with
the authorship and he absolutely denied it—then I was quite certain,”
‘Words of such keen satire came with extraordinary effect from
aman so eminently gentle and considerate, and so free from any
touch of jealousy or self-assertion as Darwin. They made a deep
and lasting impression on me—all the more because they were
spoken very quietly and deliberately, and because they were the
only words of censure I heard used by the greatest of naturalists.’
OWEN AND EVOLUTION IN 1881 29
end. How completely he abandoned it, and how
sharp was the contrast between him and a still
surviving warrior of the ‘Old Guard’, remains as ,
one of my earliest and clearest memories of the
scientific world. The stage was the meeting of
the British Association at York, in 1881, when
Prof. O. C. Marsh described the Berlin skeleton
of Archaeopteryx. The lizard-like characteristics
of the earlier fossil in the British Museum—
bought, it was said, at the price of a dowry for a
professor’s daughter—were far more clearly
displayed in the later find. Prof. Marsh told me
that he would have given almost any sum to
_ secure this—probably the most valuable and
interesting fossil in the world—for the museum
at Yale. ‘I dare not do it,’ was the reply. ‘We
let the other go, and I really believe they would
kill me if I sold this one.’ So Prof. Marsh,
obliged to study the wonderful ancestral bird in
Berlin, came, fresh from his work, to tell us
about it at York. |
Owen, presiding over the zoological section at
which the paper was read, seemed quite enthu-
siastic over Archaeopteryx, and had not a word of
criticism for the evolutionary history which it
unfolded. He discoursed sweetly upon the teeth,
believed to have been discovered in embryonic
parrots, and, with his suave manner and venerable
appearance, created a very pleasant impression.
An entirely different scene was enacted, a day or
two later, in the geological section, where Prof.
30 FIFTY YEARS OF DARWINISM
H. G. Seeley exhibited a restoration of the same
fossil. Dr. Wright, the palaeontologist, old and
deaf, but staunch as ever, would have none of it.
‘ Archaeopteryx hasn’t got a head. How can it
possibly have teeth?’ he asked angrily, thinking
of the older specimen in the British Museum.
But even in this, the remains of the head,
detached from the body, had been made out by
Sir John Evans in a corner of the block of oolite,
while the teeth were found scattered over the
surface of the stone. Prof. Newton’s emphatic
assertion that the bird had teeth left him quite
unshaken, and even after Prof. Marsh, called on
by the chairman, had drawn their form on the
blackboard, and the section was proceeding to
other business, Dr. Wright could be heard
muttering savagely, ‘Archaeopteryx is a very
good bird.’ And its excellence was in his
opinion obviously incompatible with reptilian
affinity. Disbelief in evolution was with him a
matter of faith and could never have been
affected by any amount of evidence.
About twelve years after the appearance of the
Origin, another opponent, St. George Mivart,
produced something of the same bitterness as
Owen, and for a similar reason. Thus Darwin
wrote to Hooker, Sept. 16, 1871, as follows :—
‘You never read such strong letters Mivart wrote to me
about respect towards me, begging that I would call on him,
etc., etc. ; yet in the Q. Review (July, 1871] he shows the
greatest scorn and animosity towards me, and with un-
‘~ MIVART’S INCONSISTENCY 81
common cleverness says al] that is most disagreeable. He
makes me the most arrogant, odious beast that ever lived.
I cannot understand him ; I suppose that accursed religious
bigotry is at the root of it. Of course he is quite at liberty
to scorn and hate me, but why take such trouble to express
something more than friendship? It has mortified me
a good deal.’ !
On other occasions at a much later date I have
myself observed that there was something peculiar
about the poise of Mivart’s mind, which seemed
ever inclined to pass, with abrupt transition,
from the extreme of an unnecessary effusiveness
to an unnecessarily extreme antagonism.
Mivart’s attack, contained in his book, The
Genesis of Species, was effectively dealt with by
Chauncey Wright in the North American Review
for July, 1871. Darwin was so pleased with this
defence that he obtained the author's permission
for an English reprint,? and with further additions
it was published as a pamphlet by John Murray
in 1871. A copy presented by Darwin to the
late J. Jenner Weir, and now in the library of
the Hope Department of the Oxford University
Museum, contains an interesting holograph letter
referring to the pamphlet and bearing upon the
controversy that followed upon the appearance of
Mivart’s book. This letter is, by kind permission
of Mr. Francis Darwin, now made public :—
? More Letters, i. 333, See also Life and Letters, iii. 146-50.
* The pamphlet was published at Darwin’s expense. For his
keenly appreciative letters to the author, see Life and Letters, iii.
145, 146.
32 FIFTY YEARS OF DARWINISM
Down,
Beckenham, Kent.
Oct. 11, 1871.
My Dear Sir
I am much obliged for your kind note and invitation.
I sh® like exceedingly to accept it, but it is impossible.
I have been for some months worse than usual, and can
withstand no exertion or excitement of any kind, and in
consequence have not been able to see anyone or go any-
where.—As long as I remain quite quiet, I can do some
work, and I am now preparing a new and cheap Edit” of the
Origin in which I shall answer Mr. Mivart’s chief objections.
Huxley will bring out a splendid review on d° in the
Contemporary R., on November Ist.
I am pleased that you like Ch. Wright’s article. It seemed
to me very clever for a man who is not a naturalist. He is
highly esteemed in the U. States as a Mathematician and
sound reasoner.
I wish I could join your party.—
My dear Sir .
Yours very sincerely
Cu. Darwin.'
Chauncey Wright speaks of presenting, in his
review of Mivart, considerations ‘in defence and
illustration of the theory of Natural Selection.
My special purpose,’ he continues, ‘has been to
contribute to the theory by placing it in its proper
relations to philosophical inquiries in general.’®
This able critic in America, and Henry Fawcett
in England, represent a class of thinkers who
have taken and still take a very important part
in upholding the theory of Natural Selection. It
1 The letter is addressed to J. Jenner Weir, Esq., 6 Haddo
Villas, Blackheath, London, 8.E. -
2 In a letter to "Darwin, June 21, 1871. Life and Letters, iii.
143, 144,
Pod
«
ee
ry :
az
THE VALUE OF EXTERNAL SUPPORT 838
is not necessary to be a biologist in order to
comprehend the details and the bearings of this
theory. At the outset, when naturalists them-
selves were often hopelessly puzzled, the theory
was clearly understood by able thinkers who were
not students of biology, or indeed in some cases
of any of the sciences. And at the present time
such support is of the highest importance when,
within the boundaries of the sciences most nearly
concerned, the intense and natural desire to try
all things is not always accompanied by the
steadfast purpose to hold fast that which is good.
LAMARCK’S HYPOTHESIS AND THE HEREDITARY
TRANSMISSION OF ACQUIRED CHARACTERS
The greatest change in evolutionary thought,
since the publication of the Origin, was wrought,
after Darwin’s death, by the appearance of that
wonderful and beautiful theory of heredity which
looks on parents as the elder brother and sister of
their children. In this theory, itself an outcome
of minute and exact observation (see p. 39),
Weismann raised the question of the hereditary
transmission of acquired characters, the very
foundation of Lamarckian and Spencerian evolu-
tion. Darwin accepted this transmission, and it
was in order to account for ‘such facts as the
inherited effects of use and disuse, &c.,”! that
he thought out his marvellous hypothesis of
1 See the letter to Huxley, July 12 (1865 ?), in Life and Letters,
iii, 44,
D
84 FIFTY YEARS OF DARWINISM
pangenesis. If such effects be not transmitted,
pangenesis becomes unnecessary and Weismann’s
simpler, more convincing, and better supported
hypothesis of the continuity of the germ-plasm
takes its place. It is impossible on the present
occasion to speak in any detail of the controversy
which has raged intermittently during the past
twenty years on this fascinating subject. I will,
however, briefly consider a single example of the
error into which, as I believe, Darwin was led by
following the Lamarckian theory of hereditary
experience. I refer to the interpretation which
he suggests for feelings of ‘ the sublime’, applying
this term to the effect upon the brain of a vast
cathedral, a tropical forest, or a view from a
mountain height. Thus, writing to E. Gurney,
July 8, 1876, Darwin said on this subject:
‘... possibly the sense of sublimity excited by
a grand cathedral may have some connection with
the vague feelings of terror and superstition in
our savage ancestors, when they entered a great
cavern or gloomy forest.’ !
An interesting account is given by Romanes?
of Darwin’s own experience of these feelings,
relating how he at first thought that they were
most excited by the magnificent prospect surveyed
from one of the summits of the Cordilleras, but
afterwards came down from his bed on purpose
to correct this impression, saying that he felt
most of the sublime in the forests of Brazil.
1 Life and Letters, iii. 186. ® Thid., 54,55. See also i. 64, 65.
FEELINGS OF THE SUBLIME 35
We may first observe that the remarkable
feelings induced by such experiences are very far
from unpleasant, as we should expect them to be
on the theory which refers them to the apprehen-
sions and dangers of our primitive ancestors.
Thus, on May 18, 1832, when the first impressions
of a Brazilian forest were freshest in Darwin’s
mind, he wrote to Henslow, telling him of an
expedition of 150 miles from Rio de Janeiro to
the Rio Macao.
‘Here I first saw a tropical forest in all its sublime
grandeur—nothing but the reality can give any idea how
wonderful, how magnificent the scene is....I never
experienced such intense delight. I formerly admired
Humboldt, I now almost adore him; he alone gives any
notion of the feelings which are raised in the mind on first
entering the Tropics.’ '
Furthermore, how are we to account on any
such hypothesis for the similarity of the feelings
excited by the forest, where enemies might lurk
unseen, and the mountain peak, the very spot
which offers the best facility for seeing them?
It is also difficult to understand why the terrors
of primitive man should be specially associated
with caves or with the most magnificent forests
on the face of the earth.2 There is no valid
reason for believing that any less danger lurked
amid trees of ordinary size or lay in wait for him
by the riverside, in the jungle, or the rock-strewn
) Life and Letters, i. 236, 237,
* There is grave doubt whether the New World was inhabited
by man until long after the Palaeolithic Age.
D2
36 FIFTY YEARS OF DARWINISM
waste. In the midst of life he was in death in
every solitary place that could afford cover to an
enemy ; on the mountain-top probably least of all.
The feelings inspired by the interior of a
cathedral are especially instructive in seeking
the explanation of the psychological effect. We
may be sure that the result is here produced by
the unaccustomed scale of the aesthetic impres-
sion. A cathedral the size of an ordinary church
would not produce it. However intensely we
may admire, the sense of the sublime is not
excited or but feebly excited by the exterior of
a cathedral, nor does it accompany the profound
intellectual interest aroused by the sight of the
Pyramids. The thrill of the sublime, in the
sense in which the term is here used, is, I do
not doubt, the result of surprise and wonder
raised to their highest power—a_ psychological
shock at the reception of an aesthetic visual
experience on an unwonted scale—vast, as if
belonging to a larger world in which the insignifi-
cance of man is forced upon him. It is not
excited by the Pyramids, which are in form but
symmetrical hills of stone, nor does the exterior
of any building afford an experience sufficiently
remote to produce the feeling in any high degree.
W. J. Burchell, in one of his letters’ to Sir
William Hooker, points out that the feelings of
awe and wonder aroused in a Brazilian forest
1 Preserved in the Library at Kew, but, I believe, as yet un-
published.
FEELINGS OF THE SUBLIME 87
are not to be expected in those to whom the
sight is familiar. As regards the depth and
nature of the effects produced by the experiences
here referred to, it would be very interesting to
compare the savage with the civilized man, the
uneducated with the educated mind. That the
results are intimately bound up with the psycho-
logical differences between individuals—in part
inherent, in part due to training and experience —
is well illustrated in a story told by the late
Charles Dudley Warner, who took two English
friends to see for the first time the Grand Canyon
of the Colorado. When they reached the point
where the whole prospect — boundless beyond
imagination—is revealed in a moment of time,
one of his friends burst into tears, while the
other relieved his feelings by unbridled blasphemy.
The remarkable psychological effects of a
grandeur far transcending and far removed from
ordinary experience may be compared to the
thrill' so often felt on hearing majestic music—
a thrill we do not seek to explain as a faint,
far-off reminiscence of dread inspired by the
savage war-cry. I do not doubt that an ex-
planation of the sublime based on the terrors
of our primitive ancestors is an example of the
mistaken interpretations into which even Darwin
was led by following the hypothesis of Lamarck.
? Darwin spoke of his backbone shivering during the anthem in
King's College chapel. Life and Letters, i. 49 ; see also 170.
38 FIFTY YEARS OF DARWINISM
FRANCIS DARWIN ON THE TRANSMISSION OF
ACQUIRED CHARACTERS
One of the most recent attempts to defend
the Lamarckian doctrine of the hereditary trans-
mission of acquired characters is contained in the
important Presidential Address of Mr. Francis
Darwin to the British Association at Dublin
(1908). In this interesting memoir the author
expresses the belief that such transmission is
implied by the persistence for unnumbered gene-
rations of the successive developmental stages
through which the individual advances towards
maturity. Following Hering and Richard Semon,
he is disposed to explain the hereditary trans-
mission of these stages by a process analogous
to memory. It is interesting to observe that
this very analogy had been brought before
Charles Darwin, but. failed to satisfy him. He
wrote to G. J. Romanes, May 29, 1876 :—
‘I send by this post an essay by Hiackel attacking Pan..
and substituting a molecular hypothesis. If I understand
his views rightly, he would say that with a bird which
strengthened its wings by use, the formative protoplasm of
the strengthened parts became changed, and its molecular
vibrations consequently changed, and that these vibrations
are transmitted throughout the whole frame of the bird, and
affect the sexual elements in such a manner that the wings
of the offspring are developed in a like strengthened manner.
. . . He Jays much stress on inheritance being a form of
unconscious memory, but how far this is part of his molecular
vibration, I do not understand. His views make nothing
clearer to me; but this may be my fault.’'
1 More Letters, i. 364. See also the following sentence in a letter
WEISMANN’S THEORY SUFFICIENT 39
Should it hereafter be proved that acquired
characters are inherited, I cannot. but think that
the interpretation will be on the lines of Charles
Darwin’s hypothesis of Pangenesis, But the
probability that any such result will be estab-
lished, already shown to be extremely small,
has become even more remote in the light of
the recent investigations conducted by Mendelians
and Mutationists.
For the transmission of all inherent qualities,
including the successive stages of individual de-
velopment, Weismann’s hypothesis of the con-
tinuity of the germ-plasm supplies a sufficient
mechanism. I remember, more than twenty
years ago, asking this distinguished discoverer
how it was that the hypothesis arose in his mind.
He replied that when he was working upon the
germ-cells of Hydrozoa he came to realize that
he was dealing with material which—early and
late in the history of the individual—was most
carefully preserved, as though it were of the
most essential importance for the species. If
on Pangenesis, written June 3, 1868, to Fritz Miiller :—‘ 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,’
—More Letters, ii. 82: also quoted in Life and Letters, iii. 84. The
following passage in a letter to Sir Joseph Hooker, Feb. 28, 1868,
is also of great interest :—‘ When you or Huxley say that a single
cell of a plant, or the stump of an amputated limb, has the
‘* potentiality of reproducing the whole—or “ diffuses an in-
fluence’, 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 develop-
ment, I gain a distinct idea.’—Life and Letters, iii. 81.
40 FIFTY YEARS OF DARWINISM
the efficient cause of the stages of individual
development (ontogeny) resides in the fertilized
ovum—as we cannot doubt—then Weismann’s
hypothesis satisfactorily accounts for their heredi-
tary transmission. For the portion of the ovum
set aside to form the germ-cells from which the
next generation will arise is reserved with all
its powers, and includes the potentiality of these
stages no less than the other inherent character-
istics of the individual.
It is, I think, unfortunate to seek for analogies
—and vague analogies they must always be—
between heredity and memory. However much
we have still to learn about it, memory is, on its
physiological side, a definite property of certain
higher cerebral tissues,—a property which has
clearly been of the utmost advantage in the
struggle for life, and bears the stamp of adapta
tion. Compare, for instance, the difficulty in
remembering a name with the facility in recog-
nizing a face. Adaptation would appear to be
even more clearly displayed in the unconscious
registration in memory and the instant recogni-
tion of another individual as seen from behind
or when partially concealed. Such memory is
quite independent of the artistic power. Without
any intelligent appreciation of what is peculiar
to another individual, his characteristic features
are stored up unconsciously, so that when seen
again he is instantly recognized.
One other consideration brought forward by
ae
INDIVIDUAL ADJUSTABILITY 41
Mr. Francis Darwin may be briefly discussed.
It is well known that plants have the power of
adjusting themselves to their individual environ-
ment, and that such adjustment may beneficially
take the place of a rigid specialization. The fixed
condition of plants renders this power especially
necessary for them, and the hereditary trans-
mission of the results of its exercise especially
dangerous. Where the seed falls, there must
the plant grow. The parent was limited to one
out of many possible environments ; the offspring
may grow in any of them, and for one that would
hit off the precise conditions of the parent and
would benefit by inheriting the parental response,
numbers would have to live in different surround-
ings and might be injured by the hereditary bias.
Mr. Francis Darwin calls attention to the leaves
of the beech, which in the interior shaded parts
of the tree possess a structure different from that
exhibited on the outer parts more freely exposed
to light. The structure of the shaded leaves
resembles that apparently stereotyped in trees
always adapted to shade, and Mr. Francis Darwin
is inclined to regard the permanent condition as
a final result of the hereditary transmission of
the same response through a large number of
generations. |
The development of shade foliage in the beech
is, I presume, a manifestation of a power widely
spread among animals and probably among plants
also—a power of producing a definite individual
42 FIFTY YEARS OF DARWINISM
adaptation in response to a definite stimulus. To
stereotype the result would be to convert a benefit
to the individual into an injury to the species.
The beech in a very shady place would presum-
ably develop the maximum of the shade foliage.
How disadvantageous would the hereditary bias
be to its offspring that happened to grow in more
exposed situations. But, it is argued, in plants
subject to a permanent condition we do meet
with a permanent structure, just as if repetition
had at length produced a hereditary result. The
answer to this argument seems to me to be
complete. When conditions are uniform and
no power of individual adaptation is required,
Natural Selection, without attaining the power,
would produce the permanent and _ hereditary
result in the usual way. If, however, a species,
already possessing the power, ultimately came
to live permanently in one set of conditions and
thus ceased to need it, the power itself, no longer
sustained by selection, would sooner or later be
lost.
DARWIN’S VIEWS ON EVOLUTION BY -
‘MUTATION’
It is interesting to note that the word ‘ Muta-
tion’ appears at one time to have suggested itself
to Darwin! in order to express the evolution or
This seems clear from the following passage in a letter
written Feb. 14 pales to Rev. L. Blomefield (Jenyns): ‘Thanks
for your hint about terms of “ mutation”, etc.; I had some
suspicions that it was not quite correct, and yet 1 do not yet see
‘amy
a
‘MUTATION’ REJECTED BY DARWIN 43
descent with modification of species, by no means
implying change by large and sudden steps as
in the usual modern acceptation of the term.
Indeed, the words ‘mutable’, ‘mutability’, and
their opposites, have never been employed with
the special significance now attached to ‘muta-
tion’. Every one believes in the mutability of
species, but opinions differ as to whether they
change by mutation.
It is a mistake to suppose that Darwin did
not long and carefully consider large variations,
or ‘mutations’, as supplying the material for
evolution. Writing to Asa Gray as early as
August 11, 1860, he said of great and sudden
variation :— |
‘I have, of course, no objection to this, indeed it would be
a great aid, but I did not allude to the subject, for, after
much labour, I could find nothing which satisfied me of the
probability of such occurrences. There seems to me in
almost every case too much, too complex, and too beautiful
adaptation, in every structure to believe in its sudden pro-
duction.’!
In the twenty years between 1860 and 1880 we
find that Darwin was continually brought back to
this subject by his correspondents, and by reviews
and criticisms of his works. Scattered over this
period we find numbers of letters in which he
expressed his disbelief in an evolution founded
my way to arrive at any better terms. It will be years before
I publish, so that I shall have plenty of time to think of better
words. Development would perhaps do, only it is applied to the
ag, De of an individual during its growth.’—More Letters, i. 50.
See also p. 22 n. 1. Life and Letters, ii, 333.
44 FIFTY YEARS OF DARWINISM
on ‘sudden jumps’ or ‘ monstrosities’, as well as
on ‘large’, ‘extreme’, and ‘great and sudden
variations’ (see Appendix B, p. 254). Out of
many examples I select one more because of its
peculiar interest.
The Duke of Argyll, in his address to the
Royal Society of Edinburgh, Dec. 5, 1864, used
the following words :— Strictly speaking, there-
fore, Mr. Darwin’s theory is not a theory of the
Origin of Species at all, but only a theory on the
causes which lead to the relative success and
failure of such new forms as may be born into the
world.’ In a letter to Lyell, Jan. 22, 1865.
Darwin wrote concerning this argument :—
‘I demur .. . to the Duke’s expression of ‘‘ new births”.
That may be a very good theory, but it is not mine, unless
indeed he calls a bird born with a beak 3th of an inch
longer than usual “‘a new birth”; but this is not the sense
in which the term would usually be understood. The more
I work, the more I feel convinced that it is by the accumu-
lation of such extremely slight variations that new species
arise.’ ?
We therefore find that when the Duke criti-
cized Darwin’s theory of Natural Selection as
though it had been founded on mutation, -the
interpretation was repudiated by Darwin himself.
I desire again to state most emphatically that,
during the whole course of his researches and
reflections upon evolution, Darwin was thoroughly
1 Scotsman, Dec. 6, 1864.
2 Life and Letters, iii. 33. See also Quarterly Review, July, 1909,
25, 26; also 10-12.
ave a
~_ dnt
DARWIN’S SURE JUDGEMENT 45
aware of the widespread large variations upon
which the mutationist relies. He had the material
before him, he formed his judgement upon it, and
on this memorable day it seems specially appro-
priate to show how extraordinarily sure his scien-
tific instincts were wont to be. This will be
made clear by a few examples of the solutions
which Darwin found for problems which at the
time had either not been attempted at all or had
been very differently interpreted.
Darwin’s explanation of coral islands and atolls,
at first generally accepted, was afterwards called
in question. Finally, the conclusive test of a
deep boring entirely confirmed the original theory.
Perhaps the most remarkable case is that of the
permanence of ocean basins and continental
areas, a view which Darwin maintained single-
handed in Europe, although supported by Dana
in America, against Lyell, Forbes, Wallace,
Hooker and all others who had written on the
subject. Darwin considered it mere waste of
time to speculate about the origin of life; we
might as well, he said, speculate about the origin
of matter. Nothing hitherto discovered has
shaken this opinion, which is expressed almost
in Darwin’s words in Prof. Arrhenius’ recent
work. In the fascinating subject of geographical
distribution we now know that Darwin antici-
pated Edward Forbes in explaining the alpine
arctic forms as relics of the glacial period (see
' Worlds in the making. English transl., London (1908), 218.
46 FIFTY YEARS OF DARWINISM
p. 128, ». 2), while he interpreted the poverty of
the Greenland flora and the reappearance of north
temperate species in the southern part of South
America as results of the same cause. Almost
as soon as the facts were before him in Wol-
laston’s memoirs, Darwin had interpreted the
number of wingless beetles in oceanic islands
as due to the special dangers of flight. He
anticipated H. W. Bates’ hypothesis of Mimicry,
but drove it from his mind because he did not
feel confident about the geographical coincidence
of model and mimic (see pp. 123, 124). Long
before the Origin appeared, Darwin had thought
over and rejected the idea that the same species
could have more than a single origin, or could
arise independently in two different countries—
a hypothesis very popular in later years, but,
I believe, now entirely abandoned (see Appendix
A, p. 247).
I should wish to advance one further con-
sideration before concluding this section of my
address. Certain writers on mutation seem to
hold the view that Natural Selection alone pre-
vents large variations from often holding the
field and Jeading on to great and rapid changes of
species. Such a view is not supported by the
history of species which inhabit situations com-
paratively sheltered from the struggle, such as
fresh water, caves, certain islands, or the depths
of the ocean. Organisms in these places tend to
preserve their ancestral structure more persis-
ISOLATED FORMS ANCESTRAL 47
tently than in the crowded areas where Natural
Selection holds more potent sway.
The grounds for this conclusion, stated by
Y Darwin half a century ago, should be seriously
; considered by those who are inclined to follow
| de Vries in his rash speculations on the periodic
mutation of species. The following statements
iN are to be found in Darwin’s letters to Lyell :—
‘A monad, if no deviation in its structure profitable to it
under its excessively simple conditions of life occurred, might
remain unaltered from long before the Silurian Age to the
present day.’?
, ‘With respect to Lepidosiren, Ganoid fishes, perhaps
Ornithorhynchus, I suspect, as stated in the Origin, that they
have been preserved, from inhabiting fresh-water and isolated
parts of the world, in which there has been less competition
and less rapid progress in Natural Selection, owing to the
fewness of individuals which can inhabit small areas ; and
where there are few individuals variation at most must be
slower.’ ’ ;
‘ I quite agree with you on the strange and inexplicable fact
of Ornithorhynchus having been preserved, and Australian
Trigonia, or the Silurian Lingula. I always repeat to myself
that we hardly know why any one single species is rare or
common in the best-known countries. I have got a set of
notes somewhere on the inhabitants of fresh water ; and it is
singular how many of these are ancient, or intermediate
forms ; which I think is explained by the competition having
been less severe, and the rate of change of organic forms
having been slower in small confined areas, such as all the
fresh waters make compared with sea or land.’ ®
? Oct. 11, 1859. Life and Letters, ii. 210.
* Feb. 18, 1860. More Letters, i. 143, See Origin of Species,
ed. vi, 83, 112.
5 Sept. 12, 1860. Life and Letters, ii. 340. See also Quarterly
Review, July, 1909, 21, 22.
48 FIFTY YEARS OF DARWINISM
EVOLUTION CONTINUOUS OR DISCONTINUOUS
Darwin fully recognized the limits which may
be set to the results achieved by the artificial
selection in one direction of individual variations.
Thus he wrote, Aug. 7, 1869, to Sir Joseph
Hooker :—
‘IT am not at all surprised that Hallett has found some
varieties of wheat could not be improved in certain desirable
qualities as quickly as at first. All experience shows this
with animals; but it would, I think, be rash to assume,
judging from actual experience, that a little more improve-
ment could not be got in the course of a century, and theoreti-
cally very improbable that after a few thousands [of years]
rest there would not be a start in the same line of variation.’ ’
The conception of evolution hindered or for
a time arrested for want of the appropriate varia-
tions is far from new. The hypothesis of organic
selection was framed by Baldwin, Lloyd Morgan,
and Osborn to meet this very difficulty, as ex-
pressed in the following paragraph quoted from
the present writer’s address to the American
Association for the Advancement of Science at
the Detroit meeting, Oct. 15, 1897 :—
‘The contention here urged is that natural selection works
upon the highest organisms in such a way that they have
become modifiable, and that this power of purely individual
adaptability in fact acts as the nurse by whose help the
species .. . can live through times in which the needed
inherent variations are not forthcoming.”?
1 More Letters, i. 314.
2 Development and Evolution, J. M. Baldwin, New York (1902), 350.
Ke
THE LIMITS TO VARIATION 49
It has already been shown that Darwin entirely
recognized the limits which individual variations,
or, as they are called by de Vries, ‘ fluctuations,’ !
may set to the progress achieved by artificial
selection, and that he admitted the necessity
of waiting for a fresh ‘start in the same line’.
In this respect he agreed with modern writers on
mutation ; but differed from them in believing
that the fresh start would ultimately be made.
He also differed, as has been already abundantly
shown, in the magnitude assigned to the varia-
tions forming the steps of the onward march of
evolution. His observation and study of nature
led him to the conviction that large variations,
although abundant, were rarely selected, but
that evolution proceeded gradually and by small
1 It is to be feared that confusion will result from Dr. A. E.
Shipley’s treatment of this subject in his address to the Zoological
Section of the British Association at Winnipeg as reported in the
Times of Aug. 28, 1909. The account of Dr. Shipley’s address—
5 arb probably widely read — contains the following statement : —
‘ Mutations were variations arising in the germ-cells and due to ©
causes of which we were wholly ignorant ; fluctuations were varia- —
tions arising in the body or “soma” owing to the action of external
conditions. The former were undoubtedly inherited, the latter very
eel not.’ The term ‘Fluctuation’ or ‘Fluctuating Variability ’
as been applied by de Vries to what Darwin called ‘ individual
variability ',—‘ determining the differences which are always to be
seen between parents and their children, or between the children
themselves’ (Species and Varieties, H. de Vries, 1906, 190). To
speak of these differences as ‘very probably not’ inherited, is to
follow neither Darwin, nor Weismann, nor de Vries, but simply
to cause gratuitous confusion by questioning an accepted con-
clusion based upon universal experience. The reported statement
as to the nature of fluctuations would, if it were correct, prove that
the hereditary transmission of acquired characters takes place on
the vastest imaginable scale. But, although no one disputes that
fluctuations are hereditary, very few indeed will agree that they
are due ‘to the action of external conditions’, or in other words
‘acquired characters’. See Appendix D, p. 258.
E
50 FIFTY YEARS OF DARWINISM
steps,—that it was ‘continuous’, not ‘discon-
tinuous’.
In his Presidential Address! to the British
Association at Cape Town in 1905, Sir George
Darwin argued from analogy against the ‘ con-
tinuous transformation of species’. It is impor-
tant to observe that the word ‘ continuous’ here
expresses uniformity in the rate of specific change,
and does not refer, as in the present address,
to the minuteness of the steps by which the
change is effected. The argument itself, which
is of great interest, is as follows :—
‘In the world of life the naturalist describes those forms
which persist as species ; similarly the physicist speaks of
stable configurations or modes of motion of matter ; and the
politician speaks of States. The idea at the base of all
these conceptions is that of stability, or the power of resist-
ing disintegration. In other words, the degree of persistence
or permanence of a species, of a configuration of matter, or
of a State depends on the perfection of its adaptation to its
surrounding conditions.’
After maintaining that the stability of states
rises and declines, culminating when it reaches
zero in revolution or extinction, and that the
physicist witnesses results analogous with those
studied by the politician and the historian, the
author continues :—
' Report Brit. Assoc. (1905), 8. In this address as originally
delivered and printed in Fifty Years of Darwinism I fell into the
error of believing that Sir George Darwin was advocating evolution
by large steps. I was misled by the consideration that the word
‘continuous’ as used in the present address is a subject of contro-
versy among biologists, whereas a ‘ continuous transformation’ in
Sir George’s sense would not, as I believe, be supported by any
naturalist.
RATE OF SPECIFIC CHANGE 51
‘ These considerations lead me to express a doubt whether
the biologists have been correct in looking for continuous
transformation of species. Judging by analogy we should
rather expect to find slight continuous changes occurring
during a long period of time, followed by asomewhat sudden
transformation into a new species, or by rapid extinction.’
In order to clear up any doubts about the sense
in which the word ‘ continuous’ is here employed,
the following footnote is appended to Sir George
Darwin’s address :—
‘If we may illustrate this graphically, I suggest that the
process of transformation may be represented by long lines
of gentle slope, followed by shorter lines of steeper slope.
The alternative is a continuous uniform slope of change. If
the former view is correct, it would explain why it should
not be easy to detect specific change in actual operation.
Some of my critics have erroneously thought that I advocate
specific change per saltum.’
Biologists are doubtless prepared to agree with
the author’s conclusions. Indeed, there is no
reason for the belief that they have ever looked
for a continuous and uniform rate of specific
change,—so clear has been the evidence afforded
by the persistence of ancestral forms in certain
areas as compared with their modification or
extinction in others (see pp. 46, 47).
THE FIFTIETH ANNIVERSARY OF THE ORIGIN
OF SPECIES—A RETROSPECT
That the Origin of Species, of which Darwin said
‘It is no doubt the chief work of my life’,! should
" These words are used in the autobiography (1876): Life and
Letters, i. 86. See also the following passage in the letter written
to Hooker in July, 1844, the month in which Darwin finished the
E 2
52 FIFTY YEARS OF DARWINISM
have been bitterly attacked and misrepresented
in the early years of the last half-century is quite
intelligible ; but it is difficult to understand the
position of a recent writer who maintains that
the book exercised a malignant influence upon
the interesting and important study of species
and varieties by means of hybridism. As regards
these researches its appearance, we are told, ‘ was
the signal for a general halt’;! upon them
Natural Selection ‘descended like a numbing
spell’ ;? and, if we are still unsatisfied with his
fertility in metaphor, the author offers a further
choice between the forty years in the wilderness *
and the leading into captivity.‘
Francis Galton, in his reply as a recipient
of the Darwin-Wallace Medal on July 1, 1908,
recalled the effect of the Linnean Society Essay
and the Origin. The dominant feeling, he said,
was one of freedom.’ The liberty of which Galton
spoke was freely offered to every student of hy-
bridism. No longer brought up against the blank
wall of special creation, he could fearlessly follow
his researches into all their bearings upon the
evolution of species. And this had been clearly
second and full account of his views (see pp. 6, 87): ‘I hate
argument from results, but on my views of descent, really Natural
History becomes a sublimely grand result-giving subject (now you
may quiz me for so foolish an escape of mouth).’—Life and Letters,
ae Brit. Assoc. (1904), 575. 2 1. ¢., p. 576,
° oe ane of Heredity, W. Bateson (1902), 104.
5 Darwin-Wallace Celebration of the Linnean Society of London
(1908), 26.
DARWIN AND HYBRIDISM 53
foreseen by Darwin when, in 1837, he opened
his first notebook and set forth the grand pro-
gramme which the acceptance of evolution would
unfold. He there said of his theory that ‘it
would lead to study of . . . heredity’, that ‘it
would lead to closest examination of hybridity
and generation’. In the Origin itself the admir-
able researches of Kélreuter and Girtner on these
very subjects received the utmost attention, and
were brought before the world far more promi-
nently than they have ever been either before or
since. Furthermore, the only naturalist who can
be described as a pupil of Darwin’s was strongly
advised by him to repeat some of Girtner’s
experiments.! It is simply erroneous to explain
the neglect of such researches as a consequence
of the appearance of the Origin and the study
of adaptation. So far from acting as a ‘numbing
spell’ upon any other inquiry, adaptation itself
has been nearly as much neglected as hybridism,
and for the same reason—the dominant influence
upon biological teaching of the illustrious com-
parative anatomist Huxley, Darwin’s great general
in the battles that had to be fought, but not
a naturalist, far less a student of living nature.
The momentous influence of the Origin upon
the past half-century, as well as that strange lack
? Darwin's letter of Dec. 11, 1862, to John Scott, contains the
following words:—‘If you have the means to repeat Girtner's
experiments on variations of Verbascum or on maize (see the
Origin), such experiments would be pre-eminently important.’
—More Letters, i, 221, 222.
54 FIFTY YEARS OF DARWINISM
of the historic sense which alone could render
possible the comparisons I have quoted, require
for their appreciation the addition of yet another
metaphor to the series we have been so freely
offered.
The effect of the Origin upon the boundless
domain of biological thought was as though the
sun had at length dispelled the mists that had
long enshrouded a vast primaeval continent. It
might then perhaps be natural for some primi-
tive chief to complain of the strong new light
that was flooding his neighbours’ lands no less
than his own, thinking in error not inexcusable
at the dawning of the intelligence of mankind,
that their loss must be his gain.
And now in my concluding words I have done
with controversy. .
Fifty years have passed away, and we may be
led to forget their deepest lesson, may be tempted
to think lightly of the follies and the narrow-
ness, as they appear to us, of the times that are
gone. This in itself would be a narrow view.
The distance from which we look back’on the
conflict is a help in the endeavour to realize its
meaning. Huxley's Address on The Coming of
Age of the Origin was a paean of triumph. Tyndall,
his friend, further removed from the struggle
by the nature of his life-work, realized its pathos
when he spoke in his Belfast Address of the pain
of the illustrious American naturalist who was
forced to recognize the success of the teachings he
THE PATHOS OF THE CONFLICT 55
could not accept, the naturalist who dictated in
the last year of his life the unalterable conviction
that these teachings were false.
I name no names, but I think of leaders of
organie evolution in this Continent and in Europe,
—sons of great men to whom the new thoughts
brought deepest grief, men who _ struggled
tenaciously and indomitably against them. And
full many a household unknown to fame was the
scene of the same poignant contrast, was torn by
the same dramatic conflict.
We have passed through one of the world’s
mighty bloodless revolutions ; and now, standing
on the further side, we survey the scene and are
compelled to recognize pathos as the ruling
feature.
The sublime teachings which so profoundly
transformed mankind were given by Him who
came not to bring peace on earth but a sword.
And so it isin all the ages with every high creative
thought which cuts deep into ‘the general heart
of human kind’. It must bring when it comes
division and pain, setting the hearts of the fathers
against the children and the children against the
fathers.
The world upon which the thoughts of Darwin
were launched was very different from the world
to which were given the teachings of Galileo and
the sublime discoveries of Newton. The imme-
diate effect of the first, although leading to the
bitter persecution of the great Italian, was re-
56 FIFTY YEARS OF DARWINISM
stricted to the leaders of the Church ; the influence
of the second was confined to the students of
science and mathematics, and was slow in pene-
trating even these. Nor did either of these high
achievements of the human intellect seriously
affect the religious convictions of mankind. It
was far otherwise with the teachings of the
Origin of Species; for in all the boundless realm
of philosophy and science no thought has brought
with it so much of pain, or in the end has led to
so full a measure of the joy which comes of
intellectual effort and activity, as that doctrine
of Organic Evolution which will ever be asso-
ciated, first and foremost, with the name of
Charles Robert Darwin. .
‘
os
4
y
II
THE PERSONALITY OF CHARLES
DARWIN
Written from the notes of a speech delivered at the
Darwin Banquet of the American Association for the
Advancement of Science, Baltimore, Jan. 1, 1909.
Ir is of special interest, on the evening of this
New Year's Day so happily devoted to the memory
of Charles Darwin, to think of the man himself,
and trace the influence of his personal qualities
in helping to achieve the vast intellectual trans-
formation of the past half-century.
Professor H. H. Turner has shown how nearly
the mighty genius of Newton was lost to the
world (see pp. 85, 86), and in the case of Darwin
the margin of safety appears to have been even
narrower. In the first place it was necessary that
he should be freed from the continuous labour of
income-making and from all those strains which
are at times inevitable even in the easiest of pro-
fessional careers. Darwin always recognized his
dependence upon this indispensable condition,
and remembered the debt of gratitude which
he owed to the ability and generosity of his
father. ‘You have no idea during how short
58 THE PERSONALITY OF CHARLES DARWIN
a time daily I am able to work. If I had any
regular duties, like you and Hooker, I should
do absolutely nothing in science,’! he wrote to
Huxley. But financial independence was not
the only nor indeed the most essential condition
under which Darwin’s life-work became possible.
Francis Darwin has told us, in touching and
beautiful words, of the loving care with which
his father’s delicate health was safeguarded and
sustained.
‘It is, I repeat, a principal feature of his life, that for
nearly forty years he never knew one day of the health of
ordinary men, and that thus his life was one long struggle
against the weariness and strain of sickness. And this
cannot be told without speaking of the one condition which
enabled him to bear the strain and fight out the struggle to
the end.’?
Darwin’s life, in the supreme need which can
be gathered from these pathetic words, was also
brightened by a full measure of the happiness
which comes to a father who is devoted to his
children. We are told of one of his sons, about
four years old, offering him sixpence if he would
only leave his work and come and play with
them. ‘ We all knew the sacredness of working
1 July 20,1860. More Letters, i. 158.
2 Life and Letters, i. 160. See also the beautiful passage in
Darwin’s autobiography which expresses his indebtedness to his
wife. It was omitted from the Life and Letters published during
Mrs. Darwin’s lifetime, but has now appeared in More Letters, i. 30.
The following sentence from a letter written by Darwin to his
brother: Erasmus bears upon an opinion that has often been
expressed: ‘I do not believe it [sea-sickness] was the cause of my
subsequent ill-health, which has lost me so many years,’ June 30,
1864.— More Letters, 1. 247.
_—-
THE CLAIM OF DARWIN’S HEALTH 59
time, but that any one should resist sixpence
seemed an impossibility.’! His children followed
the custom of children in general in making the
delightful assumption that their own father’s
work must be the work of every properly con-
stituted father. Thus, one of Darwin’s children
is said to have asked in regard to a neighbour
‘Then where does he do his barnacles?’* Simi-
larly, one of my own daughters, at the fascinating
age when the letter ‘r’ is apt to be an insoluble
mystery, invented a little romance in which she
supposed herself to be the child of a shepherd.
A friend, who entered into the spirit of the game,
inquired ‘Then where’s your father?’, and re-
ceived as the most natural answer in the world,
‘Oh! he’s in his labotwy.’
The interest of regular work was essential for
Darwin’s health and comfort ; while his ill health, —
by preventing work, raised a barrier against re-
covery. Thus for the sake of his health every-
thing was subordinated to work; while for the
sake of the work his health was watched over
with a double care and anxiety.
The inexorable claim of Darwin’s precarious
health leads naturally to a subject which has
been widely misunderstood and treated with
much mistaken judgement. In the brief auto-
biography, written for the members of his family,
Darwin states* that up to the age of thirty or
1 Life and Letters, i. 136. 2 More Letters, i. 38.
5 Life and Letters, i. 100-102, written in 1881. See also 33, 49,
and 69, written in 1876.
60 THE PERSONALITY OF CHARLES DARWIN
beyond it he took great interest and felt intense
delight in poetry and music, and to a less extent
in pictures. Thus on the voyage of the Beagle,
when it was only possible to take a single volume
on an expedition, he always chose Milton. Later
on in life, he says that his mind underwent a
change. He found poetry intolerably dull and
could not endure to read a line of it; he also
almost lost his taste for pictures and much of his
former exquisite pleasure in fine scenery, while
music set him thinking too energetically for his
comfort. This alteration, described with charac-
teristic candour and simplicity, but with too great
modesty, has often been the subject of comment,
and Darwin’s life has in this respect been pointed
to as an example to be avoided. Yet it is easy to
understand how the change came on, and why it
is only a superficial reading of the facts which
ean find anything in the illustrious naturalist’s
career but the finest example for man to look
up to and attempt to imitate.
Darwin’s weakness of health came on between
the return from the voyage in 1886 and the
removal from London to Down in 1842,—the
very period at which, as he tells us, his aesthetic
tastes began to alter.
The ill health seems to have enesaed rapidly
towards the close of this period. Thus he wrote
as late as Jan. 20, 1839, of being ‘ fond of talking ’
and ‘ scarcely ever out of spirits ’,! while the letters
1 More Letters, i. 29.
A COMMON ERROR CORRECTED 61
to Fitz-Roy in 1840 and to Lyell in 1841 speak
despondently of the prospects of future work and
seem to indicate that Darwin felt the weakness
even more severely than in the later years of his
life.
‘These two conditions—permanent ill-health and a
passionate love of scientific work for its own sake—deter-
mined thus early in his career, the character of his whole
future life. They impelled him to lead a retired life of
constant labour, carried on to the utmost limits of his
physical power, a life which signally falsified bis melancholy
prophecy.’*
It was an inevitable result of this permanent
ill health which prevented Darwin in the later
years of his life from saying with Huxley, ‘1
warmed both hands before the fire of life.’ ?
When his health was at its best Darwin could
only work four hours, or at most four and a half
hours in the day; when it was worse than usual
the period was reduced to an hour or an hour and
a half, while for long stretches of time—many
months together—he could do no work at all.
I have already said that work was necessary for
1 Life and Letters, i. 272. See also iii. 91, where Mr. Francis
Darwin shows that the necessity for constant labour became even
more imperative in later years. ‘He could not rest, and he
recognized with regret the gradual change in his mind that
rendered continuous work more and more necessary to him as he
grew older.’ The passage refers to the years 1867 and 1868.
2 The first line of Landor's beautiful and dignified verse would
have been hardly appropriate to Huxley, although singularly so
to Darwin :—
‘I strove with none, for none was worth my strife.
Nature I loved, and next to Nature, Art:
I warmed both hands before the fire of life:
It sinks, and I am ready to depart.’
62 THE PERSONALITY OF CHARLES DARWIN
his health —‘ nothing else makes me forget my
ever-recurrent uncomfortable sensations, —and
in order to maintain it the most perfect regu-
larity was necessary, the absence of all effort
in other directions, all excitement. During his
regular hours Darwin worked ‘with a kind of
restrained eagerness ’, expending his strength up
to the furthest possible limit, so that he would
suddenly stop in dictating, ‘with the words,
“T believe I mustn’t do any more”. It is
quite clear that, with his health as it was, no
other effort was possible to Darwin during that
day. Professor Bradley has spoken of the
errors of interpretation due to the reading of
Shakespeare with a slack imagination;! and
any literature worth calling literature demands
effort on the part of the reader. Effort was the
one thing Darwin could not give. The ordering of
Darwin's life was entirely controlled by the two
inexorable and interdependent demands of work
and health. |
‘It was a sure sign that he was not well when he was idle
at any times other than his regular resting hours; for, as
long as he remained moderately well, there was no break
in the regularity of his life. Week-days and Sundays passed
by alike, each with their stated intervals of work and rest.
It is almost impossible, except for those who watched his
daily life, to realise how essential to his well-being was the
regular routine that I have sketched: and with what pain
and difficulty anything beyond it was attempted. Any
public appearance, even of the most modest kind, was an
1 Shakespearean Tragedy, London, 1904, 349.
WORK ESSENTIAL FOR DARWIN 68
effort to him. In 1871 he went to the little village church
for the wedding of his elder daughter, but he could
hardly bear the fatigue of being present through the short
service.’ ’
The holidays and recreations in which men
find relief from overwork and gain renewed
strength were closed to Darwin. He rarely left
his home except when his researches were inter-
rupted by illness, and it was hoped that a change
of air or visit to a hydropathic establishment
would enable him to resume work on his return
home. This alone could bring him comfort, and,
although never entirely idle during his enforced
absence, for this he was longing all the time.
The inevitable conditions under which. Darwin
could keep up his slender stock of health and
strength and continue his work are expressed
again and again in his correspondence. A few
passages bearing on the subject are quoted
below, and others will be found in Appendix C,
p. 256; and in the series of nineteen letters
to Mr. Roland Trimen on pp. 218-46. References
to the limits imposed by health are to be found
in nine of these letters, viz. Nos. 4, 5, 6, 7, 8, 14,
17, 18, and 19. Darwin has been wrongly judged
by many who have read his autobiography, is still
wrongly judged, as will be shown on pp. 79, 80,
and it is important, by repeated evidence, to show
the true cause of the changes which he described
in himself.
1 Life and Letters, i. 127, 128,
64 THE PERSONALITY OF CHARLES DARWIN
The autobiography (1876) contains these
words :—
‘My chief enjoyment and sole employment throughout
life has been scientific work ; and the excitement from such
work makes me for the time forget, or drives quite away, my
daily discomfort.’’
The four following passages are all taken from
letters to Sir Joseph Hooker :—
1858. ‘It is an accursed evil to a man to become so
absorbed in any subject as I am in mine.’?
1861. ‘... I cannot be idle, much as I wish it, and am
never comfortable except when at work. The word holiday
is written in a dead language for me, and much I grieve
at it.’®
1863. The same inability to find enjoyment in
a holiday is expressed in the following passage,
which also includes a humorous allusion to the
ease with which his work was interrupted :—
‘, .. Notwithstanding the very pleasant reason you give
for our not enjoying a holiday, namely, that we have no
vices, it is a horrid bore. I have been trying for health’s
sake to be idle, with no success. What I shall now have to
do, will be to erect a tablet in Down Church, ‘‘ Sacred to the
Memory, &c.,” and officially die, and then publish books,
‘“by the late Charles Darwin,” for I cannot think what has
come over me of late ; I always suffered from the excitement
of talking, but now it has become ludicrous. I talked lately
14 hours (broken by tea by myself) with my nephew, and I
was [ill] half the night. It is a fearful evil for self and
family.’ *
1868. ‘... lama withered leaf for every subject except
Science.. It sometimes makes me hate Science, though God
1 Life and Letters, i. 79. 2 Oct. 138. Life and Letters, ii. 139.
3 Feb. 4. Ibid., 11. 360. * Jan. 3. Ibid., iii. 5,
WORK ESSENTIAL FOR DARWIN 65
knows I ought to be thankful for such a perennial interest,
which makes me forget for some hours every day my
accursed stomach.’ !
Prof. Judd tells of the deep debt to science
which Darwin expressed to him on his last visit
to Down, and how, having recently become
possessed of an increased income,
‘he was most anxious to devote what he could spare to
the advancement of Geology or Biology. He dwelt in the
most touching manner on the fact that he owed so much
happiness and fame to the natural-history sciences which
had been the solace of what might have been a painful
existence .. . Iwas much impressed by the earnestness, and,
indeed, deep emotion, with which he spoke of his indebted-
ness to Science, and his desire to promote its interests,’ ?
Final and secure confirmation of the conclusion
that Darwin’s health and comfort demanded the
employment of his whole strength and energy
upon scientific work is found in the following
touching passage from a letter written, less than
a year before his death, to the dearest of his
friends :—
‘I am rather despondent about myself, and my troubles
are of an exactly opposite nature to yours, for idleness is
downright misery to me, as I find here, as I cannot forget
my discomfort for an hour. I have not the heart or strength
at my age to begin any investigation lasting years, which is
the only thing which I enjoy; and I have no little jobs
which I can do. So I must look forward to Down grave-
yard as the sweetest place on earth.’ °
The dilemma of Darwin’s life entirely explains
that limitation of interest which has been so often
1 June 17. Life and Letters, iii. 92. 2 Thid. iii. 352, 353.
5 To Sir Joseph Hooker, June 15, 1881. More Letters, ii. 433.
F
66 THE PERSONALITY OF CHARLES DARWIN
misunderstood, and it is certain that his keenly
sympathetic and emotional nature did not in the
slightest degree suffer the injury of which he
spoke in the autobiography (1881). ‘The loss of
these tastes [the higher aesthetic tastes] is a loss
of happiness, and may possibly be injurious to the
intellect, and more probably to the moral character,
by enfeebling the emotional side of our nature.’! A
single example must suffice, but it supplies over-
whelming proof. The most dramatic episode in
the history of Darwinism was the encounter
between Huxley and the Bishop of Oxford on
the Saturday (June 30) of the meeting of the
British Association at Oxford in 1860.2- The scene
of the struggle was the northern section of the
first floor room stretching along the whole western
front of the University Museum, then just
finished. Late on Sunday night Hooker wrote to
Darwin, giving him ‘some account of the awful
battles which .... raged about species at Oxford.’
Darwin replied at once, his letter being dated
July 2 (Monday) :— .
‘IT have been very poorly, with almost continuous bad
headache for forty-eight hours, and I was low enough, and
thinking what a useless burthen I was to myself and all
others, when your letter came, and it has so cheered me ;
1 Life and Letters, i. 102.
2 A curious and interesting feature of the Saturday meeting
was the presence of Darwin’s old captain on the Beagle, Fitz-Roy,
who, in a state of frantic excitement, brandished a bible and kept
trying to make impassioned appeals to the authority of ‘the Book’.
I was told of this incident, as yet I believe unrecorded, i ve late
Mr. George Griffith; and my friend Dr. A. G. Vernon Harcourt,
F.R.S., who was also present, confirms the accuracy of the account.
DARWIN AND HIS FRIENDS 67
your kindness and affection brought tears into my eyes,
Talk of fame, honour, pleasure, wealth, allare dirt compared
with affection; and this is a doctrine with which, I know,
from your letter, that you will agree with from the bottom
of your heart.’?
These were the thoughts aroused in Darwin’s
mind by tidings of the mighty conflict over ideas
which he had brought before the world. The appeal
of the new doctrine was to the reason and the
reason alone; but the mind of man is something
more than an intellectual engine, and we can well
understand that here was a man for whom
others would fight more fiercely and tenaciously
than they would ever have done for themselves.
The touching words written to Hooker must
not obscure the fact that Darwin saw and appre-
ciated the whole significance of the fight at
Oxford. He well knew its full value, as is clearly
proved by other parts of the letter and by those
written to Huxley on July 8rd and 20th. In the
latter he said :—
‘From all that I hear from several quarters, it seems that
Oxford did the subject great good. It is of enormous im-
portance, the showing the world that a few first-rate men are
not afraid of expressing their opinion.’ *
Twenty years later, only two years before
he died, Darwin recalled the great fight in a
letter to Huxley on the subject of his lecture
‘On the Coming of Age of the Origin of Species,’
given at the Royal Institution, April 9, 1880 :-—
*, .. I well know how great a part you have played in
establishing and spreading the belief in the descent-theory,
1 Life and Letters, ii, 323. ® Life and Letters, ii, 324.
F 2
68 THE PERSONALITY OF CHARLES DARWIN
ever since that grand review in the Times and the battle
royal at Oxford up to the present day.’?
Not less important than Darwin’s attitude
towards his friends was his bearing towards
opponents,-—a bearing admirably described in
George Henry Lewes's review of Animals and
Plants under Domestication in the Pall Mall
Gazette :-—
‘We must call attention to the rare and noble calmness
with which he expounds his own views, undisturbed by the
heats of polemical agitation which those views have excited,
and persistently refusing to retort on his antagonists by
ridicule, by indignation, or by contempt. Considering the
amount of vituperation and insinuation which has come from
the other side, this forbearance is supremely dignified.’
‘Nowhere has the author a word that could wound the
most sensitive self-love of an antagonist ; nowhere does he,
in text or note, expose the fallacies and mistakes of brother
investigators . . . but while abstaining from impertinent
censure, he is lavish in acknowledging the smallest debts
he may owe; and his book will make many men happy.’?
The charming spirit in which Darwin sent a
copy of the Origin to the great American natura-
list, Louis Agassiz, is an excellent example of
his bearing towards those whom he knew to be
antagonistic :—
‘As the conclusions at which I have arrived on several
points differ so widely from yours, I have thought (should
you at any time read my volume) that you might think that
I had sent it to you out of a spirit of defiance or bravado ;
but I assure you that I act under a wholly different frame of
1 April 11, 1880. Life and Letters, iii. 241.
2 Pall Mall Gazette of Feb. 10, 15, and 17, 1868. The above-
quoted passages are well selected by Mr. Francis Darwin. See
Life and Letters, iii. 76, 77.
DARWIN AND HIS OPPONENTS 69
mind. I hope that you will at least give me credit, however
erroneous you may think my conclusions, for having
earnestly endeavoured to arrive at the truth.’'
To his over-pugnacious friend Haeckel he
wrote :—
‘,.. I think... that you will excite anger, and that
anger so completely blinds every one, that your arguments
would have no chance of influencing those who are already
opposed to our views. Moreover, I do not at all like that you,
towards whom I feel so much friendship, should unneces-
sarily make enemies, and there is pain and vexation enough
in the world without more being caused.’ ?
Another and very potent cause of the rapid
growth of the new teachings is to be found in
Darwin’s attitude towards his readers. It is
extraordinarily well described by Francis Darwin
in the great Life and Letters :—
‘The tone of .. . the ‘ Origin’ is charming, and almost
pathetic ; it is the tone of a man who, convinced of the truth
of his own views, hardly expects to convince others ; it is
just the reverse of the style of a fanatic, who wants to force
people to believe. The reader is never scorned for any
amount of doubt which he may be imagined to feel, and his
scepticism is treated with patient respect. A sceptical
reader, or perhaps even an unreasonable reader, seems to
have been generally present to his thoughts.’ *
The mind of man is ever attracted by the flame
and the hurricane of war rather than by the appeal
of the still small voice of reason. Nevertheless
it is by the still small voice that the thoughts
of the world are widened and transformed.
? Nov. 11, 1859. Life and Letters, ii. 215.
? May 21, 1867. Life and Letters, iii. 69.
5 Life and Letters, i, 156.
’
-
*
70 THE PERSONALITY OF CHARLES DARWIN
A good example of Darwin’s beautiful and
sympathetic treatment of the younger workers
who asked for help is to be found in his letter
to Prof. E. B. Wilson, quoted on p. 107. John
Scott, employed in the Botanical Garden at
Edinburgh, writing about his experiments con-
ducted along lines suggested by Darwin’s pub-
lished researches, became, in a measure, a pupil
of the illustrious naturalist. For years Darwin
devoted much time and thought not only to
Scott’s work but to giving the encouragement
so necessary to a proud, reserved, sensitive man,
with qualities very superior to those usually
found in the position in which he was placed.
‘T should be proud to be the author of the paper,’ !
he wrote, when he had at length persuaded Scott
to prepare an account of some of his investiga-
tions for the Linnean Society. And referring
to its publication he wrote to Hooker :—
‘Remember my urgent wish to be able to send
the poor fellow a word of praise from any one.’?
To the same friend he said of Scott’s letters,
‘these show remarkable talent, astonishing per-
severance, much modesty, and what I admire,
determined difference from me on many points.’ ®
A delightful spirit, boyish in its gaiety, is
revealed in Darwin’s correspondence with his
friends, and especially with the greatest of them
1 Nov. 7, 1863. More Letters, ii. 825. The paper was read
Feb. 4, 1864, and is published in Linn. Soc, Journ., viii, 1865.
2 Jan 24. 1864. More Letters, ii. 326.
8 Apr. 1, 1864. Ibid., ii, 330.
DARWIN AND YOUNGER WORKERS 71
all, Sir Joseph Hooker. The two following pas-
sages from letters to Sir Joseph have been
selected not only as examples but also because
of their intrinsic interest. In the first, Darwin
is speaking of the deplorable loss of the ancestral
flora of St. Helena.
‘You have no faith, but if I knew any one who lived in
St. Helena I would supplicate him to send me home a cask
or two of earth from a few inches beneath the surface from
the upper part of the island, and from any dried-up pond,
and thus, as sure as I’m a wriggler, I should receive a mul-
titude of lost plants.’*
‘Clematis glandulosa was a valuable present tome. My
gardener showed it to me and said, “‘ This is what they call
a Clematis,” evidently disbelieving it. So I put a little twig
to the peduncle, and the next day my gardener said, ‘‘ You
see it is a Clematis, for it feels.” That’s the way we make
out plants at Down.’ ?
Although the gardener showed an intelligent
understanding of this point in the investigation of
climbing plants, he does not appear to have been
equally appreciative of other work. Lord Avebury
tells the following story :—
‘One of his friends once asked Mr. Darwin’s gardener
about his master’s health, and how he had been lately. “Oh!”,
he said, ‘my poor master has been very sadly. I often wish
he had something to do. He moons about in the garden,
and I have seen him stand doing nothing before a flower for
ten minutes at a time. If he only had something to do
I really believe he would be better.”’* ~
: re 15, 1867. More Letters, i, 494.
sy rake 3 5, 1864. More Letters, ii. 330.
Darwin-Wallace Celebration of the Linnean Society of
ie (1908), 57, 58.
72 THE PERSONALITY OF CHARLES DARWIN
From all Darwin’s writings there shines forth
the most charming sympathy and even affection
for the animals and plants which he studied.
‘...I can hardly believe that any one could be
so good-natured as to take such trouble and do
such a very disagreeable thing as kill babies,’
he wrote, referring to a young chicken and nest-
ling pigeon required for his investigations ;1 and
in another letter—‘I appreciate your kindness
even more than before, for I have done the black
deed and murdered an angelic little fantail, and
a pouter at ten days old.’? ‘I love them to that
extent I cannot bear to kill and _ skeletonise
them,’* he wrote of his pigeons a few months
later.
The same strong humanity and love of animals
is shown in the depth of his feelings on the
subject of vivisection. ‘It is a subject which
makes me sick with horror, so I will not say
another word about it, else I shall not sleep
to-night.’‘ At the same time, he had no doubt
about the necessity or the wisdom of permitting
such experiments, and of course saw clearly that
‘the benefits will accrue only indirectly in the
search for abstract truth. It is certain,’ he con-
tinued, ‘that physiology can progress only by
1 To W. D. Fox, Mar. 19 and 27, 1855. Life and Letters, ii,
a ca 1855. Ibid, 50.
8 Nov., 1855. More Letters, i. 87 n. 1. From the context it
appears probable that the letter was written to Sir Joseph Hooker.
# To Sir Ray Lankester, Mar. 22,1871. Life and Letters, iii. 200.
See also 199-210. |
DARWIN’S LOVE FOR ANIMALS 73
experiments on living animals. Therefore the
proposal to limit research to points of which we
can now see the bearings in regard to health,
&e., I look at as puerile.' Some years later,
only a few weeks before his death, he wrote,
referring to Edmund Gurney’s articles on vivi-
section :—
‘, . . Lagree with almost everything he says, except with
some passages which appear to imply that no experiments
should be tried unless some immediate good can be predicted,
and this is a gigantic mistake contradicted by the whole
history of science.’ ?
We also meet with clear evidence of Darwin’s
love, almost always humorously expressed, for
the children of his brain, his hypotheses. Thus,
when studying the development of tendrils, he
was able to show a beautiful gradation between
these organs and leaves, but was utterly puzzled
by the vine, in which they are known to be
modified branches. He discussed the point in
a letter to Hooker, and finished up with the
words :—‘I would give a guinea if vine-tendrils
could be found to be leaves.’* Later on he dis-
covered a plant with branches possessing the
qualities which seemed essential in the fore-
runners of these sensitive organs, and he wrote
_.. To his daughter, Mrs. Litchfield, Jan. 4, 1875. Life and Letters,
i To Sir Lauder Brunton, Feb. 14, 1882. Ibid. 210; also More
Letters, ii. 441. Edmund Gurney’s articles appeared in the
Fortnightly Review, 1881, xxx. 778, and Cornhill Magazine, 1882,
xlv. 191.
5 Feb., 1864 (?). Move Letters, ii. 342.
74 THE PERSONALITY OF CHARLES DARWIN
to the same friend, ‘. . . tell Oliver I now do not
care at all how many tendrils he makes axial,
which at one time was a cruel torture to me.’ ?
Alluding to a hypothesis on the relation between
the order of development of parts in the individual
and the complexity of its organization, he wrote
to Huxley, who had expressed an adverse
opinion :—‘I shall, of course, not allude to this
subject, which I rather grieve about, as I wished
it to be true; but, alas! a scientific man ought
to have no wishes, no affections—a mere heart of
stone.’ These quotations taken alone would
give an utterly wrong impression of Darwin as
a scientific man. Two passages will be sufficient
to show that his well-balanced mind was secure
against the dangers of a too great devotion to the
creations of his brilliant imagination. ‘It is
a golden rule,’ he wrote to John Scott, ‘ which
I try to follow, to put every fact which is opposed
to one’s preconceived opinion in the strongest
light. Absolute accuracy is the hardest merit
to attain, and the highest merit. Any deviation
is ruin.’* Again, he wrote in his autobiography
in 1881 :—
‘T 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. Indeed, I have had no
choice but to act in this manner, for with the exception of
1 June 2, 1864. More Letters, ii. 348. * July 9, 1857. Ibid.,i. 98.
8 July 2, 1863 (?). More Letters, ii. 324. See also Life and Letters,
iii. 54, and ibid., i. 87, where Darwin speaks of always making
a note of hostile facts.
et
DARWIN AND HIS HYPOTHESES 75
the Coral Reefs, I cannot remember a single first-formed
hypothesis which had not after a time to be given up or
greatly modified. This has naturally led me to distrust
greatly deductive reasoning in the mixed sciences.’ '
It is impossible on the present occasion to
attempt any analysis of Darwin’s genius. I wish,
however, to show how clearly he recognized that
the love of knowledge for its own sake was the
one essential qualification for a scientific man.
In his autobiography (1881) he puts ‘the love
of science’ first among the qualities to which
he owed his success.’ But far earlier in his life,
when he was under 40, Darwin wrote to his old
teacher Henslow :—
‘I rather demur to one sentence of yours—viz., ‘* However
delightful any scientific pursuit may be, yet, if it should be
wholly unapplied, it is of no more use than building castles
in the air.” Would not your hearers infer from this that
the practical use of each scientific discovery ought to be
immediate and obvious to make it worthy of admiration ?
What a beautiful instance chloroform is of a discovery made
from purely scientific researches, afterwards coming almost
by chance into practical use! For myself I would, however,
take higher ground, for I believe there exists, and I feel
within me, an instinct for truth, or knowledge or discovery,
of something of the same nature as the instinct of virtue,
1 Life and Letters, i. 103, 104. See also 149, where Mr. Francis
Darwin states:—‘It naturally happened that many untenable
theories occurred to him ; but fortunately his richness of imagina-
tion was equalled by his power of judging and condemning the
thoughts that occurred to bus, He was just to his theories, and
did not condemn them unheard...’
* Life and Letters, i. 107. See also 103, where he says (1881) : —
‘What is far more important [than powers of observation, industry,
&c.], my love of natural science has been steady and ardent.
This pure love has, however, been much aided by the ambition to
be esteemed by my fellow naturalists,’
76 THE PERSONALITY OF CHARLES DARWIN
and that our having such an instinct is reason enough for
scientific researches without any practical results ever ensu-
ing from them.’
The same high motive was expressed in similar
language in a letter to his second cousin, W. D.
Fox :—
‘You do me injustice when you think that I work for
fame ; I value it to a certain extent ; but, if I know myself,
I work from a sort of instinct to try to make out truth.’ ?
The ‘higher ground’ taken by Darwin is now
recognized as the only motive cause which can
lead to scientific work at its best. The scientific
spirit is essentially and intensely antimateria-
list. The expression of an opposite opinion, in
spite of the superficial plausibility that made it at
one time popular, can only lead in these days
to humorous exaggerations such as that contained
in the toast said to have been drunk at a Cam-
bridge mathematical. society :—‘To the latest
discovery in pure mathematics, and may it never
be of the slightest use to anybody.’
One other dominant element in Darwin’s genius
which has been sometimes forgotten, must be
referred to. I mean the power thus described
in the autobiography (1881) :—
‘, .. I think that I am superior to the common run of
men in noticing things which easily escape attention, and in
observing them carefully.’ *
1 April 1, 1848. More Letters, i. 61.
2 Mar. 24, 1859. Life and Letters, ii. 150.
° Life and Letters, i. 103. The editors of More Letters (i. 72)
speak of ‘that supreme power of seeing and thinking what the
rest of the world had overlooked, which was one of Darwin’s most
striking characteristics’.
DARWIN AND NEWTON 77
In attempting to estimate the position of Darwin
in the intellectual history of his country and of
the world, I will quote the opinion of one whose
interests are literary rather than scientific. Lord
Courtney, proposing the toast of ‘The Royal
Society’ at the anniversary dinner a few years
ago, compared the scientific with the literary con-
tribution made by the English-speaking nations to
the brief list of the world’s greatest men. In
literature of course there was Shakespeare, but
who could be placed as a second? ‘Many,’
said the speaker, ‘would propose Milton. Our
continental friends might suggest for us Byron’ ;
but for himself Lord Courtney was inclined to
think that Shakespeare stood in that great world-
list alone, without an English-speaking rival or
even a second. When, however, he turned to
science, the speaker expressed his belief that
two names must be admitted as our contribution.
I accept the opinion and believe that it will be
widely accepted. So far as we can estimate such
positions and make such comparisons, Newton
and Darwin stand together and for all time in
the select company of the greatest men the
world has ever seen.
Ill
THE DARWIN CENTENARY AT OXFORD
The Oxford Celebration of the hundredth anniversary of
the birth of Charles Darwin, Feb. 12, 1809.
THe hundredth anniversary of the birth of
Charles Darwin was celebrated at Oxford on
the evening of Feb, 12, 1909, by a reception
held in the Examination Schools by Professors
S. H. Vines, G. C. Bourne, and E. B. Poulton.
The reception was honoured by the presence
of four sons of Charles Darwin—Mr, William
Erasmus Darwin, Sir George Darwin, Mr. Francis
Darwin, and Major Leonard Darwin ; as also by
that of Professor Judd and Professor Meldola.
No attempt was made to extend the commemora-
tion widely beyond the limits of Oxford, but .
invitations were sent to all the names upon the
list of Congregation, and the great anniversary
was celebrated, as had been intended, by a large
gathering of members of the University. Among
these several non-residents were able to be present,
including Sir William Thiselton-Dyer, Dr. D. H.
Scott, President of the Linnean Society of London,
Professor J. B. Farmer, and Dr. P. Chalmers
Mitchell.
Mr. Julian Huxley, a grandson of the late
Professor Huxley, Mr. H. Moseley, son of the
~- ss ath all -
- *
?
’
*
OLD ERRORS REPEATED 79
late Professor H. N. Moseley, Mr. Geoffrey
Smith, Mr, R. Bourne, Mr, A. F. Coventry, and
Mr, E. P. Poulton acted as stewards.
Special distinction was conferred upon the
celebration by the deeply interesting speeches
of Sir George Darwin and Mr. Francis Darwin.
An address by the present writer was based upon
material contained in the two previous addresses,
a special point being made of the true interpreta-
tion to be placed upon those changes in Darwin’s
mind, described on pp. 59, 60, which have been
so widely and unfortunately misunderstood. It
was to the speaker a supreme pleasure to find
that the interpretation was entirely accepted by
Darwin’s sons, and to hear it brought forward
in Mr. William Darwin’s speech at the Cambridge
banquet on June 23rd,—a speech which charmed
and delighted every one who had the privilege
of listening to it.
There was good and sufficient reason for direct-
ing special attention to this point; for on the
previous day (Feb. 11) the first and principal
article in the Literary Supplement of the Times,
entitled Literature and Science, was devoted to
this very subject, repeated the old errors and
spoke of them as unquestioned facts. The author
referred to
‘The unchallenged assumption, so widespread in these
days, that science is not truly science unless it is free from
all suspicion of poetic exaltation, and that poetry is a place
of dreams and divinations which are chilled by the touch of
science.”
80 THE DARWIN CENTENARY AT OXFORD
He considered that we must reckon with
‘the fact that to give the mind full and free play in one
direction seems as yet to imply the atrophy of its activities
in the other.’
The article was evidently written for the
anniversary, and that the visionary antagonism
which so unnecessarily distressed the author was
founded on the misinterpretation of Darwin’s life
is clear from the following passage :—
‘If a man so utterly incapable of taking an intolerant or
a contemptuous view of the life of art could yet find that his
own work produced in him the decay of all faculty of
artistic enjoyment, we have indeed a proof of the extent to
which the two temperaments have diverged.’
The author spoke also of the fine intellectual
training, conferred by the combined ‘ austerity and
responsiveness’ of Darwin’s work, as one which
nevertheless ‘ leaves untouched and undeveloped,
positively even starves, the faculty of aesthetic
enjoyment’. And he finally touched the high-.
water mark in these astounding words :—
_ *The case of a man given up to scientific investigations,
who yet reads Shakespeare without finding him so dull as
to be nauseating, is a case which stands out, which is
remarked, which is felt to be notable. As long as this is so
we must take Darwin’s case to be typical of the rule.’
I will not call this statement an exaggeration,
and thus imply that it contains a minute kernel
of truth: I unhesitatingly affirm that it is wholly
and utterly false. Few can be happier than
I in the intimate friendship of scientific men,
Fi ‘
+s ,
aS wea
7 -
Gas — i
‘
a‘ ty
hat
AN INDEFENSIBLE CHARGE 81
—British, American, and Continental,—men fol-
lowing every branch of science ; and yet, with this
wide experience, I do not know a single one to
whom the author’s words could be fairly applied.
Speaking for myself, if I may venture upon what,
in the circumstances is not a piece of unnecessary
egotism, I would gratefully record the refresh-
ment and delight which I have ever found in the
works of the English poets, I allude to it, because
one who keenly feels this pleasure only too easily
detects and is chilled by the want of appreciation
of it in others, I should not indeed be surprised
if the author’s charge against scientific men were
true of certain students of literature, men who
seem to have triumphed over our conventional
tests—in the letter so exacting, so heedless of
the spirit—by means of a knack or trick, and
emerge victorious without any perceptible trace
of refinement or of interest in any subject, even
their own. Such men compare unfavourably
with one of our greatest professional exponents
of the most difficult of all games, who confessed
that, although he did not really care for golf, he
was devoted to poaching.
In this protest, which I have felt it my duty to
make, I do not in any way question the author’s
good faith. It is evident in every line, while the
article, when not concerned with the supposed
tastes of scientific men, shows great breadth of
view and keen penetration, The extraordinary
misstatements are due in the first place to the
G
82 THE DARWIN CENTENARY AT OXFORD
common misinterpretation of Darwin’s experience,
in the second to false assumptions about a class of
workers of whom the author evidently knows
nothing. His views on the relation between the
creative efforts of the imagination in science and
in art are true and clear-sighted. They are admir-
ably expressed in the following passage :—
‘Darwin had, of course, like many lesser men, an
immense power of observing and storing facts; but that
after all concerned merely the preparation of the stage, so
to speak, which was thus swept and lighted for his genius
to occupy. The work of his genius was, as he put it, to
grind out general laws, or, rather, as we may more sym-
pathetically phrase it, to take the sudden imaginative leap,
seizing the exact moment which justifies it, from the
particular to the general. To that moment all the patient
and impartial amassing of evidence was subsidiary. We
may see in that moment, when it arrived, a strong appeal
to the imagination on one side, met by an immediate
response to it on the other. To fix the eye successively
upon detail, and at the critical instant to shift the focus so
as to embrace the whole mass—that is not a process which
implies the suppression of imagination. It is a process
which means for the imagination a continual and austere
exercise—austere because every vague or unmeaning impulse
is forbidden, continual because the mind must be unceasingly
alert to catch the moment for its leap. It approaches very
near, we surely begin to see, to the process by which, for
the artist, a thousand different fragments of perception are
transmuted into the single symbolic image which embraces
and explains them all.’
It is an unfortunate result of the inevitable
specialization of the present day that one who
could write so well of science should know
absolutely nothing of scientific workers, It is
Sl ey
os o
Oe
~~
SCIENCE AND LITERATURE 83
still more unfortunate that, knowing nothing, he
should publish his conclusions about them. And
yet scientific men, extreme specialists as they
are and must be in their researches, are not
without some knowledge of the lives and interests
of their literary and artistic comrades.
It is not necessary or desirable to consider here
the hypothesis by which the author explains
to his own satisfaction an antagonism which only
exists in his imagination. But it is right to say
a few words about his treatment of science as
something essentially modern. The sciences are
not new. Aristotle, it has been well said, was
just the kind of man one would expect to meet at
the Royal Society or in the Athenaeum. But the
spirit of science goes back far beyond the days of
Aristotle, to the dawning of the love of knowledge
in the developing mind of man, to that primaeval
time when wonder first became mingled with
delight as he looked upon the world around him.
But the ancient desire to find out the ways of
nature is gratified in an inexhaustible field where
every fulfilment brings a new desire and fresh
territory. For this reason the comradeship of
scientific men is both stimulating and encouraging
to the followers of literature, poring, as so many of
them do, over world-worn themes of matchless
dignity and beauty, but breathing all the time
an atmosphere which tends to over-develop the
purely critical faculties and to leave the creative
imagination dwarfed and stunted.
G2
IV
CHARLES DARWIN AND THE UNIVER-
SITY OF CAMBRIDGE
Revised from the shorthand notes of a speech delivered
on June 23rd, 1909, at the Banquet given by the University
of Cambridge in honour of the Delegates to the Darwin
Celebration.
CHANCELLOR, your Excellencies, my Lords and
Gentlemen, it is a proud position to be asked, as
a representative of the University of Oxford, to
propose, on this memorable occasion, the toast
of ‘The University of Cambridge’. It is with
considerable diffidence that I attempt to fill it.
The greatness of a University may be most
truly measured by the greatness of its sons, and
by the force of the intellectual movements to
which it has given rise. Mr. Balfour has spoken
of the mighty names borne by sons of Cambridge.
I trust that I shall enlist your sympathy in
dwelling for a few moments on the University
life of one of the greatest of these, the illustrious
man whom we commemorate to-day, and also in
attempting very briefly to show how his mature
thoughts were received in both the ancient
Universities of this country. It was in Cam-
bridge, as you know well, that Charles Darwin
a
ale ™
.?
be
>
-—:
DARWIN'S DEBT TO HENSLOW 85
came under the guidance of Professor Henslow,
a circumstance which, as he said, influenced
his whole career more than any other. To
Henslow he owed the possibility of sailing in
the Beagle, the greatest event, as he believed, in
his scientific life—the one event which made all
the rest possible! We must also remember how
Darwin’s interest in geology was aroused by
Professor Sedgwick. It was on his return from
a geological tour in North Wales with Sedgwick
that Darwin found the letter from Henslow,
offering him the post on the Beagle. However
lightly it was regarded by Darwin himself, there
can be no doubt of the great depth of his debt to
Cambridge. 7
In thinking over the names of the great
men who have sprung from the University of
Cambridge, I have been led to reflect on the long
harmonious years of sisterhood between our two
ancient Universities, to remember how the
thoughts that have arisen in the one have been
strengthened by resonance in the other, to call to
mind the dependence of the greatest of men upon
appreciation and sympathy.
Professor H. H. Turner has recently shown
that the shy and sensitive genius of Newton,
irritated by the correspondence with Hooke,
might perhaps have been altogether lost to
? “The voyage of the Beagle has been by far the most important
event in my life, and has determined my whole career. . . I have
always felt that I owe to the voyage the first real training or
education of my mind...’ Life and Letters, i. 61.
86 DARWIN AND CAMBRIDGE
Science, were it not for the ‘immortal journey’
to Cambridge made by the Oxford man Halley
in August, 1684.
Through the relationship and mutual inter-
dependence between great minds we can also
trace the influence of Oxford upon Darwin.
Sir Ray Lankester spoke this morning of the
debt which Lyell owed to the teaching of
Buckland at Oxford, and how similar it was to
the debt which Darwin owed to Henslow at
Cambridge. But there is the strongest evidence,
given in Darwin’s own words, that he also owed
a deep debt to Lyell, and therefore sc to
Buckland and Oxford.
The first volume of the first edition of Lyell’s
Principles of Geology came out in 1880, just
before Darwin started on the voyage of the
Beagle. He was advised by Henslow to read it,
but on no account to believe the views therein
contained ; but Darwin was proud to remember.
that, at the very first opportunity of testing Lyell’s
reasoning, he recognized the infinite superiority
of his teachings over those of all others. Many
years later he wrote to L. Horner: ‘I always
feel as if my books came half out of Lyell’s
DRAIN 6 3.6:e.5 I have always thought that the great
merit of the Principles was that it altered the
whole tone of one’s mind, and therefore that,
when seeing a thing never seen by Lyell, one yet
saw it partially through his eyes.’ !
1 See also pp. 5-7.
DARWIN’S DEBT TO LYELL 87
When did Darwin acknowledge his debt in
this way? It was on Aug. 29th, 1844. In 1842
he had written the first brief account of his
theory of evolution—that sketch which will now
be for the first time in the hands of the public—
that sketch of which, thanks to your generosity, a
gift has been made to every guest whom you are
welcoming to Cambridge, a work which I for my
part look forward to reading with greater pleasure
and greater interest than any book I have ever
possessed. In 1844 Darwin had further
elaborated this sketch into a completed essay
which he felt, whatever happened, would contain
a sufficient account of his views; and on July 5
he made his ‘solemn and last request’ to his
wife, begging her, in the event of his death, to
make arrangements for its publication. Only a
few weeks after this, the psychological moment
in his career, Darwin acknowledged his debt to
Lyell; and when we consider how intensely
Lyellian were the three lines of argument—two
based on geographical distribution, and one on
the relation between the most recent fossils and
the forms now living in a country—by which
Darwin was first convinced of the truth of
evolution, we cannot avoid the conclusion that
he was right in feeling the debt to be a very
heavy one.
Although Darwin spoke of the three years at
Cambridge as ‘the most joyful in my happy life’,
neither he nor Lyell appear to have thought that
88 DARWIN AND CAMBRIDGE
they owed very much to their Universities. In
this respect I cannot but believe that both these
great men were mistaken, and I think it would
be interesting to inquire what would be likely to
happen to such men as Darwin or Lyell if they
entered Cambridge or Oxford at the present day.
I remember many years ago seeing in the
papers among the news from India a message
which read, with the quaint humour oftentimes
conferred by the abbreviation of telegraphic
dispatch: ‘A new Saint has appeared in the
Northern Provinces. The police are already on
his track.’ In not dissimilar language we must
own that when fresh genius appears at the
Universities, the examiners are hard upon its
track ; and the effect of the pressure of examina-
tions upon genius is apt to be similar to that of
the removal of Pharaoh’s chariot wheels,—so that
they drave heavily. And with regard to Darwin’s
teacher Henslow, would the Henslow of to-day
have the time and the opportunity to discover and
to influence a student who did not care to read
_ for Honours, but preferred to go into the country
to collect beetles or into the Fens to collect
plants? I do not ask these questions in any
pessimistic spirit. There is no need for despair ;
for I believe that we are all aware of the danger
of the excessive pressure of examinations at the
present moment in both our ancient Universities,
and indeed to an even greater extent throughout
the whole of the British Empire. Cambridge has
GENIUS AND THE EXAMINER 89
recently made great and important changes
precisely in the direction I am_indicating—
changes tending to relieve this pressure ; and we
in Oxford have made alterations intended to
produce the same effect. I believe we are
likely to improve still further in this matter, and,
without losing our modern efficiency, regain a
greater freedom and greater elasticity, and a freer
recognition of unusual powers—in these respects
assimilating more closely to the Universities of
three-quarters of a century ago.
Turning now to the ancient Universities as the
lists where new ideas are compelled to undergo
the trial of combat, we observe that the battle of
evolution began with the dramatic encounter
between Huxley and Wilberforce at the meeting
of the British Association at Oxford, in 1860,
and, according to Professor Alfred Newton, came
to a close with the victory of the new teachings,
only two years later, at the meeting of the same
Association at Cambridge.
Whatever happened in the great arena
furnished by the two ancient Universities, there
can be no doubt that for many years neither of
them was at all willing to accept the conclusions
of Darwin. One of the most strongly antagonistic
letters received by Darwin was written by his
old teacher, Sedgwick. Whewell kept the Origin
of Species out of the library at Trinity College
for some years; while Professor Westwood
seriously proposed to the last Oxford University
90 DARWIN AND CAMBRIDGE
Commission the establishment of a permanent
lectureship for the exposure of the fallacies of
Darwinism.
Charles Darwin was offered the honorary degree
of D.C.L. by Lord Salisbury, on his installation as
Chancellor of the University of Oxford in 1870,
After the lapse of nearly forty years there can be
no harm in the candid admission that Lord
Salisbury’s list was opposed, although unsuc-
cessfully, in the Hebdomadal Council. There is
no evidence that any special exception was taken
to the name of Darwin, but certain members
of Council objected to the high proportion of
scientific men. The opposition was unsuccessful,
the Chancellor’s list was passed as a whole, and
became the list of the Council; but, unfortunately
for Oxford, Darwin’s health prevented him from
accepting the degree. Cambridge was happier,
and Darwin became an honorary LL.D. of his
own University in 1877. |
And now there is one other subject to which I
desire to allude before proposing the toast. What
would we give to know as much about the ‘life of
Shakespeare and of Newton as we know about
the life of Darwin? That we do happily possess
a wide and detailed knowledge of the life of this
great man we owe to one of his sons, who, with
a fine and delicate sense of pathos as well as
performance, has done his work, who has hurried
in no way but has made every step secure, so that
we can with the utmost confidence receive the
THE DEBT TO FRANCIS DARWIN 91
great result as historical truth that will stand the
test of time—a sure foundation on which the
future can build. This great debt we owe. It is
difficult to express our gratitude in adequate
terms, but I should wish to say on behalf of
those of us who are here as guests of the University
of Cambridge that we look with a sympathy of
the utmost depth upon the majestic ceremony
that will take place to-morrow, when you will
make the great exception and dignify with an
honorary degree a resident Cambridge man.
I give you the toast of the ‘University of
Cambridge’, venerable yet ever young, the
mother of great men. And I know that when
you honour it you will think of one mighty name,
the noble, illustrious name of him through whom
Cambridge may not unjustly claim that she has
taught and inspired the world.
Vv
THE VALUE OF COLOUR IN THE
STRUGGLE FOR LIFE
Essay XV in Darwin and Modern Science: Essays in com-
memoration of the centenary of the birth of Charles Darwin and
of the fiftieth anniversary of the publication of ‘ The Origin of
Species’, edited by Prof. A. C. Seward, Cambridge University
Press (1909), 271-297. Somewhat extended.
INTRODUCTION.
Tue following pages have been written chiefly
from the historical standpoint. Their principal
object has been to give some account of the
impressions produced on the mind of Darwin
and his great compeer Wallace by various difficult
problems suggested by the colours of living nature.
In order to render the brief summary of Darwin’s
thoughts and opinions on the subject in any way
complete, it was found necessary to say again
much that has often been said before. No attempt
has been made to display as a whole the vast con-
tribution of Wallace ; but certain of its features
are incidentally revealed in passages quoted from
Darwin’s letters. It is assumed that the reader
is familiar with the well-known theories of Pro-
tective Resemblance, Warning Colours, and Mimi-
cry both Batesian and Miillerian. It would have
THE TREATMENT HISTORICAL 938
been superfluous to explain these on the present
occasion; for a far more detailed account than
could have been attempted in these pages has
recently appeared.1 Among the older records
I have made a point of bringing together the
principal observations scattered through the note-
books and collections of W. J. Burchell. These
have never hitherto found a place in any memoir
dealing with the significance of the colours of
animals. A few new observations which seemed to
be of special interest have been included, together
with some fresh considerations deserving of atten-
tion in the study of Mimicry in relation to sex.
INCIDENTAL COLOURS
Darwin fully recognized that the colours of
living beings are not necessarily of value as
colours, but that they may be an incidental result
of chemical or physical structure. Thus he wrote
to T. Meehan, Oct. 9, 1874:—
‘I am glad that you are attending to the colours of di-
cecious flowers; but it is well to remember that their
colours may be as unimportant to them as those of a gall,
or, indeed, as the colour of an amethyst or ruby is to these
gems,’ ?
Incidental colours remain as available assets of
the organism ready to be turned to account by
Natural Selection. It is a probable speculation
1 Poulton, Essays on Evolution, Oxford, 1908, 293-382.
2 More Letters, i. 354, 855. See also the admirable account
< incidental colours in Descent of Mau (2nd edit., 1874), 261,
62.
94 THE VALUE OF COLOUR
that all pigmentary colours were originally inci-
dental; but now and for immense periods of
time the visible tints of animals have been modi-
fied and arranged so as to assist in the struggle
with other organisms or in courtship. The domi-
nant colouring of plants, on the other hand, is an
essential element in the paramount physiological
activity of chlorophyll. In exceptional instances,
however, the shapes and visible colours of plants
may be modified in order to promote conceal-
ment.'
TELEOLOGY AND ADAPTATION
In the department of Biology, which forms the
subject of this essay, the adaptation of means to an
end is probably more evident than in any other ;
and it is therefore of interest to compare, in
a brief introductory section, the older with the
newer teleological views.
The distinctive feature of Natural Selection as
contrasted with other attempts to explain the
process of evolution is the part played by the
struggle for existence. All naturalists in all ages
must have known something of the operations of
‘Nature red in tooth and claw’; but it was left
for this great theory to suggest that vast exter-
mination is a necessary condition of progress,
and even of maintaining the ground already
gained.
Realizing that fitness is the outcome of this
1 See pp. 96-8, 102, 103.
ee
PALEY AND ADAPTATION 95
fierce struggle, thus turned to account for the first
time, we are sometimes led to associate the recog-
nition of adaptation itself too exclusively with
Natural Selection. Adaptation had been studied
with the warmest enthusiasm nearly forty years
before this great theory was given to the scientific
world, and it is difficult now to realize the impetus
which the works of Paley gave to the study of
Natural History. That they did inspire the
naturalists of the early part of the last century
is clearly shown in the following passages.
In the year 1824 the Ashmolean Museum at
Oxford was entrusted to the care of J. S. Duncan
of New College. He was succeeded in this office
by his brother, P. B. Duncan, of the same College,
author of a history of the Museum, which shows
very clearly the influence of Paley upon the study
of nature, and the dominant position given to his
teachings: ‘Happily at this time [1824] a taste
for the study of natural history had been excited
in the University by Dr. Paley’s very interesting
work on Natural Theology, and the very popular
lectures of Dr. Kidd on Comparative Anatomy,
and Dr. Buckland on Geology.’ In the arrange-
ment of the contents of the Museum the illustra-
tion of Paley’s work was given the foremost place
by J. S. Duncan :—
‘ The first division proposes to familiarize the eye to those
relations of all natural objects which form the basis of argu-
ment in Dr. Paley’s Natural Theology ; to induce a mental
habit of associating the view of natural phenomena with the
conviction that they are the media of Divine manifestation ;
96 THE VALUE OF COLOUR.
and by such association to give proper dignity to every
branch of natural science.’ !
The great naturalist, W. J. Burchell, in his
classical work shows the same recognition of
adaptation in nature at a still earlier date. Upon
the subject of collections he wrote ? :—
‘It must not be supposed that these charms [the pleasures
of Nature] are produced by the mere discovery of new
objects: it is the harmony with which they have been
adapted by the Creator to each other, and to the situations
in which they are found, which delights the observer in
countries where Art has not yet introduced her discords.’
The remainder of the passage is so admirable
that I venture to quote it :—
‘To him who is satisfied with amassing collections of
curious objects, simply for the pleasure of possessing them,
such objects can afford, at best, but a childish gratification,
faint and fleeting ; while he who extends his view beyond
the narrow field of nomenclature, beholds a boundless ex-
panse, the exploring of which is worthy of the philosopher,
and of the best talents of a reasonable being.’
On Sept. 14, 1811, Burchell was at Zand Valley
(Vlei), or Sand Pool, a few miles south-west of
- the site of Prieska, on the Orange River. . Here
he found a Mesembryanthemum (M. turbiniforme,
now M. truncatum) and also a Gryllus (Acridian),
closely resembling the pebbles with which their
locality was strewn. He says of both of these,
1 From History and Arrangement of the Ashmolean Museum, b
P. B. Duncan, A Catalogue of the Ashmolean Museum, Oxford,
(1836), vi, vil.
2 Travels in the Interior of Southern Africa, London, i. (1822),
505. The references to Burchell’s observations in the present
essay are adapted from the author's article in Report of the British
and South African Associations, 1905, iii, 57-110,
BURCHELL AND ADAPTATION 97
‘The intention of Nature, in these instances, seems to
have been the same as when she gave to the Chameleon the
{ power of accommodating its color, in a certain degree, to
SS that of the object nearest to it, in order to compensate for
the deficiency of its locomotive powers. By their form and
color, this insect may pass unobserved by those birds, which
otherwise would soon extirpate a species so little able to
elude its pursuers, and this juicy little Mesembryanthemum
may generally escape the notice of cattle and wild animals.’ !
Burchell here seems to miss, at least in part,
the meaning of the relationship between the
quiescence of the Acridian and its cryptic colour-
ing. It is a relationship of co-operation rather
than compensation ; for quiescence is an essential
element in the protective resemblance to a stone—
probably even more indispensable than the details
of the form and colouring. Furthermore, the
chameleon can make certain movements quickly
enough when occasion requires. My friend Pro-
fessor Lloyd Morgan has seen an African cha-
meleon, when a snake was brought near it,
instantaneously quit its hold of the branch, draw
in its legs, and fall like a stone to the ground.
Although Burchell appears to overlook this point
? Thid., 310, 811. See Sir William Thiselton-Dyer, ‘ Morpho-
logical Notes,’ xi. ; ‘ Protective Adaptations,’ i.; Annals of Botany,
xx, 124. In plates vii. viii. and ix. accompanying this article, the
author represents the species observed by Burchell, together with
others in which analogous adaptations exist. He writes: ‘ Burchell
was clearly on the track on which Darwin reached the goal. But
the time had not come for emancipation from the old teleology.
This, however, in no respect detracts from the merit or value of ie
work. For, as Huxley has pointed out (Husley’s Life and Letters,
1900, i. 457), the facts of the old teleology are immediately transfer-
able to Darwinism, which simply supplies them with a natural in
place of a supernatural explanation.
H
98 THE VALUE OF COLOUR
he fully recognized the community between pro-
tection by concealment and more aggressive modes
of defence; for, in the passage of which a part is
quoted above, he specially refers to some earlier
remarks on p. 226 of his vol. i. We here find
that when the oxen were resting by the Juk
rivier (Yoke river), on July 19, 1811, Burchell
observed ‘ Geraniwm spinosum, with a fleshy stem
and large white flowers. ..; and asucculent species
of Pelargonium . . . so defended by the old panicles,
grown to hard woody thorns, that no cattle could
browze upon it.’ He goes on to say, ‘In this arid
country, where every juicy vegetable would soon
be eaten up by the wild animals, the Great Creating
Power, with all-provident wisdom, has given to
such plants either an acrid or poisonous juice,
or sharp thorns, to preserve the species from
annihilation . . .’ All these modes of defence,
especially adapted to a desert environment, have
since been generally recognized, and it is very
interesting to place beside Burchell’s statement
the following passage from a letter written by
Darwin, Aug. 7, 1868, to G. H. Lewes :—
‘That Natural Selection would tend to produce the most
formidable thorns will be admitted by every one who has
observed the distribution in South America and Africa (vide
Livingstone) of thorn-bearing plants, for they always appear
where the bushes grow isolated and are exposed to the attacks
of mammals. Even in England it has been noticed that all
spine-bearing and sting-bearing plants are palatable to quad-
rupeds, when the thorns are crushed.’?
1 More Letters, i. 308.
ee ae ea
Le:
THE. NEWER AND OLDER TELEOLOGY 99
ADAPTATION AND NATURAL SELECTION
I have preferred to show the influence of the
older teleology upon Natural History by quotations
from a single great and insufficiently appreciated
naturalist. It might have been seen equally well
in the pages of Kirby and Spence and those of
many other writers. If the older naturalists who
thought and spoke with Burchell of ‘ the intention
of Nature’ and the adaptation of beings ‘ to each
other, and to the situations in which they are
found’, could have conceived the possibility of
evolution, they must have been led, as Darwin
was, by the same considerations, to Natural Selec-
tion. This was impossible for them, because the
philosophy which they followed contemplated the
phenomena of adaptation as part of a static immu-
table system. Darwin, convinced that the system
is dynamic and mutable, was prevented by these
very phenomena from accepting anything short
of the crowning interpretation offered by Natural
Selection.1 And the birth of Darwin’s unalterable
conviction that adaptation is of dominant import-
ance in the organic world,—a conviction confirmed
and ever again confirmed by his experience as
a naturalist—may probably be traced to the in-
1 *T had always been much struck by such rag enema [e. g.
woodpecker and tree-frog for climbing, seeds for dispersal], and
until these could be explained it seemed to me almost useless to
endeavour to prove by indirect evidence that species have been
modified.’ Autobiography in Life and Letters, 1. 82. The same
thought is repeated again and again in Darwin’s letters to his
(880 “ It is forcibly urged in the Introduction to the Origin
), 8.
H 2
-
oe = *" Oat ares
100 THE VALUE OF COLOUR
fluence of the great theologian. Thus Darwin,
speaking of his Undergraduate days, tells us in his
Autobiography that the logic of Paley’s Evidences of
Christianity and Moral Philosophy gave him as much
delight as did Euclid.
‘The careful study of these works, without attempting to
learn any part by rote, was the only part of the academical
course which, as I then felt and as I still believe, was of the
least use to me in the education of my mind. I did not at
that time trouble myself about Paley’s premises ; and taking
these on trust, I was charmed and convinced by the long
line of argumentation.’ ?
When Darwin came to write the Origin he
quoted in relation to Natural Selection one of
Paley’s conclusions. ‘No organ will be formed,
as Paley has remarked, for the purpose of causing
pain or for doing an injury to its possessor.’? -
The study of adaptation always had for Darwin,
as it has for many, a peculiar charm. His words,
written Nov. 28, 1880, to Sir W. Thiselton-Dyer,
are by no means inappropriate at the present day,
nor is their application by any means to be
restricted to a single nation: ‘Many.of the
Germans are very contemptuous about making
out use of organs; but they may sneer the souls
out of their bodies, and I for one shall think it
the most interesting part of natural history.’
Mr, Francis Darwin truly says :—
‘One of the greatest services rendered by my father to the
1 Life and Letters, i. 47.
2 Origin of Species (1st edit.), 1859, 201.
8 More Letters, ii. 428.
NATURAL SELECTION AND TELEOLOGY 101
study of Natural History is the revival of Teleology. The
evolutionist studies the purpose or meaning of organs with
the zeal of the older Teleology, but with far wider and more
coherent purpose.’ ?
PROTECTIVE AND AGGRESSIVE RESEMBLANCE:
PROCRYPTIC AND ANTICRYPTIC COLOURING
Colouring for the purpose of concealment is
sometimes included under the head Mimicry, a
classification adopted by H. W. Bates in his
classical paper. Such an arrangement is incon-
venient, and I have followed Wallace in keeping
the two categories distinct.
The visible colours of animals are far more
commonly adapted for Protective Resemblance
than for any other purpose. The concealment of
animals by their colours, shapes and attitudes,
must have been well known from the period at
which human beings first began to take an intel-
ligent interest in Nature. An interesting early
record is that of Samuel Felton, F.R.S., who
(Dec. 2, 1768) figured and gave some account of
an Acridian (Phyllotettix) from Jamaica. Of this
insect he says ‘the thorax is like a leaf that is
raised perpendicularly from the body ’.?
Both Protective and Aggressive Resemblances
were appreciated and clearly -explained by
Erasmus Darwin in 1794: ‘The colours of
many animals seem adapted to their purposes
' Life and Letters, iii. 255.
* Phil. Trans. Roy. Soc., liv. Tab. vi. 55.
102 THE VALUE OF COLOUR
of concealing themselves either to avoid danger,
or to spring upon their prey.”!
Protective Resemblance of a very marked
and beautiful kind is found in certain plants
inhabiting desert areas. Examples observed by
Burchell almost exactly a hundred years ago
have already been mentioned on pp. 96-8. In
addition to the resemblance to stones Burchell
observed, although he did not publish the fact,
a South African plant concealed by its likeness to
the dung of birds.2- The observation is recorded
in one of the manuscript journals kept by the
great explorer during his journey. I owe the
opportunity of studying it to the kindness of
Mr. Francis A. Burchell of the Rhodes University
College, Grahamstown. The following account is
given under the date July 5, 1812, when Burchell
was at the Makkwiarin River, about half-way
between the Kuruman River and Litakun the old
capital of the Bachapins (Bechuanas) :—
‘I found a curious little Crassula (not in flower) so snow
white, that I should never has [have] distinguished it from
the white limestones. . . . It was an inch high and a little
1 Zoonomia, i. London, 1794, 509.
? Sir William Thiselton-Dyer has suggested the same method of
concealment (Annals of Botany, xx. 123). Referring to Anacamp-
seros papyracea, figured on plate ix., the author says of its adaptive
resemblance: ‘At the risk of suggesting one perhaps somewhat
far-fetched, 1 must confess that the aspect of the plant always
calls to my mind the dejecta of some bird, and the more so owing
to the. whitening of the branches towards the tips’ (ibid., 126).
The student of insects, who is so familiar with this very form of
protective resemblance in larvae, and even | mvt insects, will not
be inclined to consider the suggestion far-fetched.
=
7S
“Tt a
he
-
CRYPTIC RESEMBLANCE IN PLANTS 103
branchy, . . . and was at first mistaken for the dung of
birds of the passerine order. I have often had occasion to
remark that in stony place{s] there grow many small succu-
lent plants and abound insects (chiefly Grylli) which have
exactly the same color as the ground and must for ever
escape observation unless a person sit on the ground and
observe very attentively.’
The cryptic resemblances of animals impressed
Darwin and Wallace in very different degrees,
probably in part due to the fact that Wallace’s
tropical experiences were so largely derived from
the insect world, in part to the importance
assigned by Darwin to Sexual Selection, ‘a subject
which had always greatly interested me,’ as he says
in his Autobiography.' There is no reference to
Cryptic Resemblance in Darwin’s section of the
Joint Essay, although he gives an excellent short
account of Sexual Selection (see pp. 139, 140).
Wallace’s section on the other hand contains the
following statement :—
‘Even the peculiar colours of many animals, especially
insects, so closely resembling the soil or the leaves or the
trunks on which they habitually reside, are explained on the
same principle ; for though in the course of ages varieties of
many tints may have occurred, yet those races haviny colours
best adapted to concealment from their enemies would inevitably
survive the longest.’ *
It would occupy too much space to attempt any
discussion of the difference between the views of
1 Life and Letters, i. 94.
® Journ. Proc. Linn. Soc., iii. 1859, 61. The italics are Wallace's.
104 THE VALUE OF COLOUR
these two naturalists, but it is clear that Darwin,
although fully believing in the efficiency of
Protective Resemblance and replying to St, George
Mivart’s contention that Natural Selection was
incompetent to produce it,' never entirely agreed
with Wallace’s estimate of its importance. Thus
the following extract from a letter to Sir Joseph
Hooker, May 21, 1868, refers to Wallace: ‘I find
I must (and I always distrust myself when I
differ from him) separate rather widely from
him all about birds’ nests and protection; he is
riding that hobby to death.’? It is clear from
the account given in The Descent of Man,’ that
the divergence was due to the fact that Darwin
ascribed more importance to Sexual Selection
than did Wallace, and Wallace more importance
to Protective Resemblance than Darwin. Thus
Darwin wrote to Wallace, Oct. 12 and 13, 1867:
‘By the way, I cannot but think that you push
protection too far in some cases, as with the
stripes on the tiger.* Here too Darwin was
preferring the explanation offered by Sexual
Selection,’ a preference which, considering the
relation of the colouring of the lion and tiger. to
their respective environments, few naturalists
will be found to share. It is also shown on
1 Origin (6th edit.), London, 1872, 181, 182, See also 66.
2 More Letters, i. 304.
5 London, 1874, 452-8. See also Life and Letters, iii, 123-5, and
More Letters, ii. 59-63, 72-4, 76-8, 84-90, 92, 93.
* More Letters, i. 283.
5 Descent of Man (2nd edit.), 1874, 545, 546.
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SEXUAL VERSUS NATURAL SELECTION 105
p. 127 that Darwin contemplated the possibility
of cryptic colours, such as those of Patagonian
animals, being due to Sexual Selection influenced
by the aspect of surrounding nature.
Nearly a year later Darwin in his letter of
May 5, 1868?, expressed his agreement with
Wallace’s views: ‘Except that I should put
sexual selection as an equal, or perhaps as even
a more important agent in giving colour than
Natural Selection for protection.’ The con-
clusion expressed in the above quoted passage is
opposed by the extraordinary development of
Protective Resemblance in the immature stages
of animals, especially insects.
It must not be supposed, however, that Darwin
ascribed an unimportant rédle to Cryptic Resem-
blances, and as observations accumulated he came
to recognize their efficiency in fresh groups of
the animal kingdom. Thus he wrote to Wallace
May 5, 1867: ‘ Hickel has recently well shown
that the transparency and absence of colour in
the lower oceanic animals, belonging to the most
different classes, may be well accounted for on
the principle of protection’? Darwin also
admitted the justice of Professor E. S. Morse’s
contention that the shells of molluscs are often
adaptively coloured.? But he looked upon cryptic
colouring and also Mimicry as more especially
Wallace’s departments, and sent to him and to
} More Letters, ii. 77, 78.
® More Letters, ii. 62. See also Descent of Man (1874), 261.
5 More Letters, ii. 95.
106 THE VALUE OF COLOUR
Professor Meldola observations and notes bearing
upon these subjects. Thus the following letter
given to me by Dr. A. R. Wallace, and now, by
kind permission, published for the first time,
accompanied a photograph of the chrysalis of
Papilio sarpedon choredon, Feld., suspended from
a leaf of its food-plant :—
July 9th Dowy,
Beckenuam, Kent.
My Dear WALLACE
Dr. G. Krefft has sent me the enclosed from Sydney.
A nurseryman saw a caterpillar feeding on a plant and
covered the whole up, but when he searched for the cocoon
[pupa], was long before he c? find it, so good was its
imitation in colour and form to the leaf to which it was
attached. I hope that the world goes well with you.—Do
not trouble yourself by acknowledging this,
Ever yours
Cu. Darwin.
Another deeply interesting letter of Darwin’s,
_ bearing upon Protective Resemblance, has only
recently been shown to me by my friend
Professor E. B. Wilson, the great American
Cytologist. With his kind consent and that of
Mr. Francis Darwin, this letter, written four
months before Darwin’s death on April 19, 1882,
is reproduced here ! :-—
1 The letter is addressed: ‘Edmund B. Wilson, Esq., Assistant in
Biology, John{s] Hopkins University, Baltimore Md., U. States.’
ole i el
DARWIN AND CRYPTIC COLOURS 107
December 21, 1881. Dowy,
Becxenuam, Kenrv.
(Railway Station,
Orpington, S.E.R.)
Dear Sir,
I thank you much for having taken so much trouble
in describing fully your interesting and curious case of
mimickry.
I am in the habit of looking through many scientific
Journals, and though my memory is now not nearly so good as
it was, I feel pretty sure that no such case as yours has been
described (amongst the nudibranch) molluscs. You perhaps
know the case of a fish allied to Hippocampus (described
some years ago by Dr. Giinther in Proc. Zoolog. Soc.”) which
clings by its tail to sea-weeds, and is covered with waving
filaments so as itself to look like a piece of the same sea-weed.
The parallelism between your and Dr. Ginther’s case makes
both of them the more interesting; considering how far
a fish and a mollusc stand apart. It w® be difficult for
anyone to explain such cases by the direct action of the
environment.—I am glad that you intend to make further
observations on this mollusc, and I hope that you will give
a figure and if possible a coloured figure.—With all good
wishes from an old brother naturalist.
I remain,
Dear Sir,
Yours faithfully,
Cuartes Darwin.
Professor E. B. Wilson has kindly given the
following account of the circumstances under
which he had written to Darwin :—
‘The case to which Darwin’s letter refers is that of the
nudibranch molluse Scyllaea, which lives on the floating
Sargassum and shows a really astonishing resemblance to
the plant, having leaf-shaped processes very closely similar
108 THE VALUE OF COLOUR
to the fronds of the sea-weed both in shape and in color.
The concealment of the animal may be judged from the fact
that we found the animal quite by accident on a piece of
Sargassum that had been in a glass jar in the laboratory for
some time, and had been closely examined in the search for
hydroids and the like without disclosing the presence upon
it of two large specimens of the Scyllaea (the animal, as
I recall it, is about two inches long). It was first detected
by its movements alone, by someone (I think a casual visitor
to the laboratory) who was looking closely at the Sargassum
and exclaimed, ‘Why, the sea-weed is moving its leaves !”
We found the example in the summer of 1880 or 1881 at
Beaufort, N.C., where the Johns Hopkins laboratory was
located for the time being. It must have been seen by many
others, before or since.
‘I wrote and sent to Darwin a short description of the
case at the suggestion of Brooks, with whom I was at the
time a student. I was, of course, entirely unknown to
Darwin (or to anyone else) and to me the principal interest
of Darwin’s letter is the evidence that it gives of his extra-
ordinary kindness and friendliness towards an obscure
youngster who had of course absolutely no claim upon his
time or attention. The little incident made an indelible
impression upon my memory and taught me a lesson that
was worth learning.’
VARIABLE PROTECTIVE RESEMBLANCE
The wonderful power of rapid colour adjust-
ment possessed by the cuttle-fish was observed
by Darwin in 1832 at St. Jago, Cape de Verd
Islands, the first place visited during the voyage
of the Beagle. From Rio he wrote to Henslow,
giving the following account of his observations,
May 18, 1832 :—
‘I took several specimens of an Octopus which possessed
a most marvellous power of changing its colours, equalling
DARWIN AND COLOUR ADJUSTMENT 109
any chameleon, and evidently accommodating the changes
to the colour of the ground which it passed over. Yellowish
green, dark brown, and red, were the prevailing colours ;
this fact appears to be new, as far as I can find out.’ !
Darwin was well aware of the power of indi-
vidual colour adjustment now known to be
possessed by large numbers of Lepidopterous
pupae and larvae. An excellent example was
brought to his notice by C. V. Riley,? while the
most striking of the early results obtained with
the pupae of butterflies—those of Mrs. M. E. Barber
upon Papilio nireus—was communicated by him
to the Entomological Society of London.*®
Before leaving the subject of Protective Resem-
blance I wish to take the opportunity of referring
to an observation on the chameleon, read by
J. S. Beuttler, Nov. 1, 1873, before the Rugby
School Natural History Society and published
in the Reports for that date. In this paper
the author remarks, ‘The side of the animal
nearest the light is invariably the darkest.’ The
same fact was observed in South Africa (1905)
by Dr. G. B. Longstaff, who kindly supplied
the above quotation, Professor C. V. Boys and
the present writer. An interpretation of the
later observation was sought along the lines of
A. H. Thayer’s classical explanation of the white
under surfaces of animals, and. the conclusion
1 Life and Letters, i. 235, 236. See also the Journal of Researches,
1876, 6-8, where a far more detailed account is given, together
with a reference to Encycl. of Anat. and Physiol.
2 More Letters, ii. 385, 386.
8 Trans, Ent. Soc. Lond., 1874, 519. See also More Letters, ii. 403.
110 THE VALUE OF COLOUR
was reached that the colour differences on the
two sides neutralize the differences in illumination,
and remove the appearance of solidity."
It is also necessary to direct attention to
C. W. Beebe’s? recent discovery that the pig-
mentation of the plumage of certain birds is
increased by confinement in a superhumid atmo-
sphere. In Scardafella inca, on which the most
complete series of experiments was made, the
changes took place only at the moults, whether
normal and annual or artificially induced at
shorter periods. There was a _ corresponding
increase in the choroidal pigment of the eye.
At a certain advanced stage of feather pigment-
ation a brilliant iridescent bronze or green tint
made its appearance on those areas where iri-
descence most often occurs in allied genera.
Thus in birds no less than in insects, characters
previously regarded as of taxonomic value, can
be evoked or withheld by the forces of the en-—
vironment.
WARNING OR APOSEMATIC COLOURS’
From Darwin’s description of the colours and
habits it is evident that he observed, in 1833,
an excellent example of warning colouring in a
little South American toad (Phryniscus nigricans).
He described it in a letter to Henslow, written
1 Zool. Journ. Linn. Soc., xxx. 45.
2 Zoologica: N.Y. Zool. Soc., i. No. 1, Sept. 25, 1907: Geographic
variation in birds with especial reference to the effects of humidity.
:
»
A
.
A TOAD WITH WARNING COLOURS 111
from’ Monte Video, Nov. 24, 18382: ‘As for
one little toad, I hope it may be new, that it
may be christened “diabolicus”. Milton must
allude to this very individual when he talks of
“squat like a toad”; its colours are by Werner
[Nomenclature of Colours, 1821] ink black, vermi-
lion red and buff orange’! In the Journal of
Researches * its colours are described as follows :
‘If we imagine, first, that it had been steeped
in the blackest ink, and then, when dry, allowed
to crawl over a board, freshly painted with the
brightest vermilion, so as to colour the soles of
its feet and parts of its stomach, a good idea
of its appearance will be gained.’ ‘Instead of
being nocturnal in its habits, as other toads are,
and living in damp obscure recesses, it crawls
during the heat of the day about the dry sand-
hillocks and arid plains,...’ The appearance
and habits recall T. Belt’s well-known description
of the conspicuous little Nicaraguan frog which
he found to be distasteful to a duck.*
The recognition of the Warning Colours of
caterpillars is due in the first instance to Darwin,
who, reflecting on Sexual Selection, was puzzled
by the splendid colours of sexually immature
organisms. He applied to Wallace, ‘ who has an
innate genius for solving difficulties.’ Darwin’s
1 More Letters, i. 12. 2 1876, 97.
* The Naturalist in Nicaragua (2nd edit.), London, 1888, 321.
* Descent of Man, 325. On this and the following page an
excellent account of the discovery will be found, as well as in
Wallace’s Natural Selection, 1875, 117-22.
112 THE VALUE OF COLOUR
original letter exists,! and in it we are told that
he had taken the advice given by Bates: ‘ You
had better ask Wallace.’ After some considera-
tion Wallace replied that he believed the colours
of conspicuous caterpillars and perfect insects
were a warning of distastefulness and that such
forms would be refused by birds. Darwin’s reply?
is extremely interesting both for its enthusiasm at
the brilliancy of the hypothesis and its caution in
acceptance without full confirmation :—
‘Bates was quite right ; you are the man to apply to ina
difficulty. I never heard anything more ingenious than
your suggestion, and I hope you may be able to prove it
true. That is a splendid fact about the white moths ;° it
warms one’s very blood to see a theory thus almost proved
to be true.’
Two years later the hypothesis was proved to
hold for caterpillars of many kinds by J. Jenner
Weir and A. G. Butler, whose observations have
since been abundantly confirmed by many natu-
ralists. Darwin wrote to Jenner Weir, May 18, -
1869 : ‘ Your verification of Wallace’s suggestion
seems to me to amount to quite a discovery.’ 4
RECOGNITION OR EPISEMATIC CHARACTERS
This principle does not appear to have been
in any way foreseen by Darwin, although he draws
special attention to several elements of pattern
1 Life and Letters, iii. 93, 94. 2 Life and Letters, iii. 94, 95.
8 A single white moth which was rejected by young turkeys,
while other moths were greedily devoured, Natural Selection,
1875, 78.
* More Letters, ii. 71 (footnote).
foe
SEXUAL VERSUS NATURAL SELECTION 113
which would now be interpreted by many natu-
ralists asepisemes. He believed that the markings
in question interfered with the cryptic effect, and
came to the conclusion that, even when common
to both sexes, they ‘are the result of sexual
selection primarily applied to the male’! The
most familiar of all recognition characters was
carefully described by him, although here too
explained as an ornamental feature now equally
transmitted to both sexes: ‘The hare on her
form is a familiar instance of concealment through
colour ; yet this principle partly fails in a closely-
allied species, the rabbit, for when running to
- its burrow, it is made conspicuous to the sports-
man, and no doubt to all beasts of prey, by its
upturned white tail.’ *
The analogous episematic use of the bright
colours of flowers to attract insects for effecting
cross-fertilization and of fruits to attract verte-
brates for effecting dispersal is very clearly ex-
plained in the Origin.*
It is not, at this point, necessary to treat sematic
characters at any greater length. They will form
the subject of a large part of the following section,
where the models of Batesian (Pseudaposematic)
Mimicry are considered as well as the Miillerian
(Synaposematic) combinations of Warning Colours.
? Descent of Man, 544. 2 Descent of Man, 542.
* Ed. 1872, 161. For a good example of Darwin's caution in
dealing with exceptions see the allusion to brightly coloured fruit
in More Letters, ii. 348
114 THE VALUE OF COLOUR
MIMICRY—BATESIAN OR PSEUDAPOSEMATIC,
MULLERIAN OR SYNAPOSEMATIC
The existence of superficial resemblances be-
tween animals of various degrees of affinity must
have been observed for hundreds of years. Among
the early examples, the best known to me have
been found in the manuscript notebooks and
collections of W. J. Burchell, the great traveller
in Africa (1810-15) and Brazil (1825-80). The
most interesting of his records on this subject
are brought together in the following paragraphs.
Conspicuous among well-defended insects are
the dark steely or iridescent greenish blue fos-
sorial wasps or sand-wasps, Sphex and the allied
genera. Many Longicorn beetles mimic these in
colour, slender shape of body and limbs, rapid
movements, and the readiness with which they
take to flight. On Dec. 21, 1812, Burchell
captured one such beetle (Promeces viridis) at Kosi
Fountain on the journey from the source of the
Kuruman River to Klaarwater. It is correctly
placed among the Longicorns in his catalogue,
but opposite to its number is the comment ‘Sphex!
totus purpureus ’.
In our own country the black-and-yellow colour-
ing of many stinging insects, especially the
ordinary wasps, affords perhaps the commonest
model for Mimicry. It is reproduced with more
or less accuracy on moths, flies and_ beetles.
Among the latter it is again a Longicorn which
, ve
; .
oa )
MIMICRY RECORDED BY BURCHELL 115
offers one of the best-known, although by no
means one of the most perfect, examples. The
appearance of the well-known ‘ wasp- beetle’
(Clytus arietis) in the living state is sufficiently
suggestive to prevent the great majority of people
from touching it. The dead specimen is less
convincing, and when I showed a painting of it
to Dr. Alfred Russel Wallace in 1889 he doubted
whether it was an example of Mimicry at all.
I replied that he would not question the inter-
pretation if he had noticed the beetle in life ;
and he at once recalled the movements of allied
forms in the Eastern Archipelago, and admitted
the mimetic resemblance. In fact, the slender,
wasp-like legs of the beetle are moved in a rapid,
somewhat jerky manner, very different from the
usual stolid coleopterous stride, but remarkably
like the active movements of a wasp, which
always seem to imply the perfection of training.’
In Burchell’s Brazilian collection there is a nearly
allied species (Neoclytus curvatus) which appears
to be somewhat less wasp-like than the British
beetle. The specimen bears the number ‘1188’,
and the date March 27, 1827, when Burchell was
collecting in the neighbourhood of St. Paulo.
Turning to the corresponding number in the
Brazilian notebook we find this record: ‘It runs
rapidly like an ichneumon or wasp, of which it
has the appearance.’
The formidable, well-defended ants are as freely
? Poulton, The Colours of Animals, London, 1890, 249, 250.
12
116 THE VALUE OF COLOUR
mimicked by other insects as the sand-wasps,
ordinary wasps and bees. Thus on Feb. 17,
1901, Guy A. K. Marshall captured, near Salis-
bury, Mashonaland, three similar species of ants
(Hymenoptera) with a bug (Hemiptera) and a
Locustid (Orthoptera), the two latter mimicking
the former. All the insects, seven in number,
were caught on a single plant, a small bushy
vetch.!
This is an interesting recent example from
South Africa, and large numbers of others might
be added—the observations of many naturalists
in many lands; but nearly all of them known
since that general awakening of interest in the
subject which was inspired by the great hypotheses
of H. W. Bates and Fritz Miller. We find, how-
ever, that Burchell had more than once recorded
the mimetic resemblance to ants. An extremely
ant-like bug (the larva of a species of <Alydus)
in his Brazilian collection is labelled ‘1141’, with
the date Dec. 8, 1826, when Burchell was at the
Rio das Pedras, Cubatio, near Santos. In the
notebook the record is as follows: ‘1141 Cimez.
I collected this for a Formica.’
Some of the chief mimics of ants are the active
little hunting spiders belonging to the family
Attidae. Many examples have been brought for-
ward during recent years, especially by my friends
Dr. and Mrs. Peckham, of Milwaukee, the great
authorities on this group of Arachnids. Here too
1 Trans. Ent. Soc. Lond., 1902, 535, plate xix, figs. 53-9.
an), Ua
j
MIMICRY RECORDED BY BURCHELL 117
we find an observation of the mimetic resemblance
recorded by Burchell, and one which adds in the
most interesting manner to our knowledge of the
subject. A fragment, all that is now left, of
an Attid spider, captured on June 30, 1828, at
Goyaz, Brazil, bears the following note, in this
case on the specimen and not in the notebook :
‘Black... runs and seems like an ant with large
extended jaws.’ My friend Mr. R. I. Pocock,
to whom I have submitted the specimen, tells me
that it is not one of the group of species hitherto
regarded as ant-like, and he adds, ‘It is most
interesting that Burchell should have noticed the
resemblance to an ant in its movements. This
suggests that the perfect imitation in shape, as
well as in movement, seen in many species was
started in forms of an appropriate size and colour
by the mimicry of movement alone.’ Up tothe
present time Burchell is the only naturalist who
has observed an example which still exhibits this
ancestral stage in the evolution of mimetic like-
ness,
Following the teachings of his day, Burchell
was driven to believe that it was part of the fixed
and inexorable scheme of things that these strange
superficial resemblances existed. Thus, when he
found other examples of Hemipterous mimics,
including one (Luteva macrophthalma) with ‘ exactly
the manners of a Mantis’, he added the sentence,
‘In the genus Cimex (Linn.) are to be found the
outward resemblances of insects of many other
118 THE VALUE OF COLOUR
genera and orders,’ Feb. 15, 1829. Of another
Brazilian bug, which is not to be found in his
collection, and cannot therefore be precisely
identified, he wrote: ‘ Cimex ... Nature seems to
have intended it to imitate a Sphex, both in colour
and the rapid palpitating and movement of the
antennae,’ Nov. 15, 1826. At the same time
it is impossible not to feel the conviction that
Burchell felt the advantage of a likeness to sting-
ing insects and to aggressive ants, just as he
recognized the benefits conferred on desert plants
by spines and by concealment (see pp. 96-8). Such
an interpretation of Mimicry was perfectly con-
sistent with the theological doctrines of his day!
The last note I have selected from Burchell’s
manuscript refers to one of the chief mimics of
the highly protected Lycid beetles. The whole
assemblage of African insects with a Lycoid
colouring forms a most important combination
and one which has an interesting bearing upon
the theories of Bates and Fritz Miller. This most
wonderful set of mimetic forms, described in 1902
by Guy A. K. Marshall, is composed of flower-
haunting beetles belonging to the family Lycidae,
and the heterogeneous series of varied insects
which mimic their conspicuous and simple scheme
of colouring. The Lycid beetles, forming the
centre or ‘models’ of the whole company, are
orange-brown in front for about two-thirds of the
1 See Kirby and Spence, An Introduction to Entomology (1st edit.),
London, ii. 1817, 223.
7
BATES’S AND F. MULLER’S THEORIES 119
exposed surface, black behind for the remaining
third. They are undoubtedly protected by quali-
ties which make them excessively unpalatable
to the bulk of insect-eating animals. Some ex-
perimental proof of this has been obtained by
Mr. Guy Marshall. What are the forms which
surround them? According to the hypothesis
of Bates they would be, at any rate mainly, pala-
table hard-pressed insects which only hold their
own in the struggle for life by a fraudulent imita-
tion of the trade-mark of the successful and
powerful Lycidae. According to Fritz Miller's
hypothesis we should expect that the mimickers
would be highly protected, successful and abun-
dant species, which (metaphorically speaking) have
found it to their advantage to possess an adver-
tisement, a danger-signal, in common with each
other, and in common with the beetles in the
centre of the group. According to the first view
the mimic is a danger to its model, according
to the second it is a benefit. If A, B, ©, D, &e.,
are all unpalatable and. all recognized by the same
appearance, and if their enemies have to learn by
experience what to eat and what to reject, it
follows that when A is tasted and found un-
pleasant, B, C, D, &c., are benefited. They would
be tasted more cautiously, or perhaps abandoned
without tasting. On the next occasion B might
be tasted by some other inexperienced foe, and
the advantage would lie with A as well as C, D,
&e. It is hardly necessary to explain that under
120 THE VALUE OF COLOUR
either hypothesis volition has nothing to do with
the growth of resemblance, but that it is believed
to be brought about by the survival in successive
generations of those individuals most like the
model or most like one another. The death of
individual A or B as a result of the tasting is
no difficulty. Far more individuals of A, B, C, D,
&e., would be killed by experimental tasting
if they had different patterns than if they had
the same, and this is advantage enough to cause
a strong trend in the direction of resemblance.
How far does the constitution of this wonderful
combination—the largest and most complicated -
as yet known in all the world—convey to us the
idea of Mimicry working along the lines supposed
by Bates or those suggested by Miller? Figures
1 to 52 of Mr. Marshall’s coloured plate’ represent
a set of forty-two or forty-three species or forms
of insects captured in Mashonaland, and all ex-
cept two in the neighbourhood of Salisbury.
The combination includes six species of Lycidae ;
nine beetles of five groups all specially protected
by nauseous qualities, Telephoridae, Melyridae,
Phytophaga, Lagriidae, Cantharidae; six Longi-
corn beetles; one Coprid beetle; eight stinging
Hymenoptera; three or four parasitic Hymeno-
ptera (Braconidae, a group much mimicked and
shown by some experiments to be distasteful); five
bugs (Hemiptera, another group in which unpalata-
1 Trans. Ent. Soc. Lond., 1902, plate xviii. See also 517, where
the group is analysed.
MARSHALL’S GREAT MIMETIC SERIES 121
bility is widespread); three moths (Arctiidae and
Zygaenidae, distasteful families); one fly. In fact
the whole combination, except perhaps one Phyto-
phagous, one Coprid and the Longicorn beetles,
and the fly, fall under the hypothesis of Miller
and not under that of Bates. And it is very
doubtful whether these exceptions will be sus-
tained: indeed the suspicion of unpalatability
already besets the mimetic Longicorns, and is
always on the heels—I should say the hind tarsi
—of a Phytophagous beetle.
This most remarkable example which illustrates
so well the problem of Mimicry and the alterna-
tive hypotheses proposed for its solution, was,
as I have said, first described in 1902. Among
the most perfect of the mimetic resemblances
in it is that between the Longicorn beetle, Amphi-
desmus analis, and the Lycidae. It was with the
utmost astonishment and pleasure that I found
this very resemblance had almost certainly been
observed by Burchell. A specimen of the Amphi-
desmus exists in his collection and it bears ‘651’,
Turning to the same number in the African
catalogue we find that the beetle is correctly
placed among the Longicorns, that it was cap-
tured at Uitenhage on Nov. 18, 1813, and that
it was found associated with Lycid beetles in
flowers (‘ consocians cum Lycis 78-87 in floribus’).
Looking up Nos. 78-87 in the collection and
catalogue, three species of Lycidae are found, all
captured on Nov. 18, 1813, at Uitenhage. Bur-
122 THE VALUE OF COLOUR
chell recognized the wide difference in affinity,
shown by the distance between the respective
numbers ; for his catalogue is arranged to repre-
sent relationships. He observed, what students
of Mimicry are only just beginning to record
precisely and systematically, the coincidence
between model and mimic in time and space and
in habits. We are justified in concluding that he
observed the close superficial likeness, although
he does not in this case expressly allude to it.
One of the most interesting among the early
observations of superficial resemblance between
forms remote in the scale of classification was
made by Darwin himself, as described in the
following passage from his letter to Henslow,
written from Monte Video, Aug. 15, 18382:—
‘Amongst the lower animals nothing has so much
interested me as finding two species of elegantly coloured true
Plamaria inhabiting the dewy forest! The false relation they
bear to snails is the most extraordinary thing of the kind
I have ever seen.’’
Many years later, in 1867, he wrote to Fritz
Miller suggesting that the resemblance of a
soberly coloured British Planarian to a slug
might be due to Mimicry.?
The most interesting copy of Bates’s classical
memoir on Mimicry,? read before the Linnean
Society in 1861, is that given by him to the man
who has done most to support and extend the
1 More Letters, i. 9. 2 Life and Letters, iii. 71.
8 «Contributions to an Insect Fauna of the Amazon Valers:
Trans. Linn. Soc., xxiii. 1862, 495.
BATES’S CLASSICAL MEMOIR 128
theory. My kind friend has given that copy to
me; it bears the inscription :—
Only a year and a half after the publication
of the Origin, we find that Darwin wrote to Bates
on the subject which was to provide such striking
evidence of the truth of Natural Selection :—
‘I am glad to hear that you have specially attended to
“ mimetic” analogies—a most curious subject ; I hope you
publish on it. I have for a long time wished to know
whether what Dr. Collingwood asserts is true—that the
most striking cases generally occur between insects inhabit-
ing the same country.’ ’
The next letter, written about six months
later, reveals the remarkable fact that the illus-
trious naturalist who had anticipated Edward
Forbes in the explanation of arctic forms on
alpine heights,’ had also anticipated H. W. Bates
in the theory of Mimicry :—
‘What a capital paper yours will be on mimetic re-
? The letter is dated April 4, 1861. More Letters, i. 183.
2 *T was forestalled in only one important point, which my
vanity has always made me regret, namely, the explanation by
means of the Glacial period of the presence of the same species
of plants and of some few animals on distant mountain summits
and in the arctic regions. This view pleased me so much that
I wrote it out in extenso, and I believe that it was read by Hooker
some yests before E. Forbes published his celebrated memoir on
the subject. In the very few points in which we differed, | still
think that I was in the right. I have never, of course, alluded
in print to my having independently worked out this view.’
Autobiography in Life and Letters, i. 88.
124 THE VALUE OF COLOUR
semblances! You will make quite a new subject of it. Ihad
thought of such cases as a difficulty ; and once, when corre-
sponding with Dr. Collingwood, I thought of your explanation ;
but I drove it from my mind, for I felt that I had not
knowledge to judge one way or the other. Dr. C., I think,
states that the mimetic forms inhabit the same country, but
I did not know whether to believe him. What wonderful
cases yours seem to be !’!
The above passage will probably be as great
a surprise to other naturalists as it was to the
present writer. It would be very interesting to
know whether Collingwood published any state-
ments on the subject. His book,? quoted by
Darwin in the Descent of Man, is dated 1868.
Bates read his paper before the Linnean
Society, Noy. 21, 1861, and Darwin’s impressions
on hearing it were conveyed in a letter to the
author dated Dec. 3 :—
‘Under a general point of view, I am quite convinced
(Hooker and Huxley took the same view some months ago)
that a philosophic view of nature can solely be driven into
naturalists by treating special subjects as you have done.
Under a special point of view, I think you have solved one
of the most perplexing problems which could be pie: to
solve.’ *
The memoir appeared in the following year,
and after reading it Darwin wrote as follows,
Nov. 20, 1862 :—
. In my opinion it is one of the most remarkable and
admirable papers I ever read in my life... .I am rejoiced
? The letter is dated Sept. 25, 1861. More Letters, i. 197.
2 C. Collingwood, Rambles of a Naturalist on the shores and
waters of the China Seas, London, 1868,
8 Life and Letters, ii, 378.
DARWIN AND BATES'S MEMOIR 125
that I passed over the whole subject in the Origin, for I
should have made a precious mess of it. You have most
clearly stated and solved a wonderful problem. . . . Your
paper is too good to be largely appreciated by the mob of
naturalists without souls; but, rely on it, that it will have
lasting value, and I cordially congratulate you on your first
great work. You will find, I should think, that Wallace
will fully appreciate it.’!
Four days later, Nov. 24, Darwin wrote to
Hooker on the same subject :—
‘I have now finished this paper . . .; it seems to me
admirable. To my mind the act of segregation of varieties
into species was never so plainly brought forward, and there
are heaps of capital miscellaneous observations.’ ?
Darwin was here referring to the tendency of
similar varieties of the same species to pair
together, and on Nov. 25 he wrote to Bates asking
for fuller information on this subject.’ If Bates’s
opinion were well founded, Sexual Selection would
bear a most important part in the establishment
of such species.t It must be admitted, however,
that the evidence is as yet quite insufficient to
establish this conclusion. It is interesting to
observe how Darwin at once fixed on the part of
Bates’s memoir which seemed to bear upon Sexual
Selection. A review of Bates’s theory of Mimicry
was contributed by Darwin to the Natural History
? Life and Letters, ii. 391-3.
? More Letters, i. 214,
5 More Letters, i. re See also parts of Darwin’s letter to Bates
in ap tate Letters, ii.
Poulton, ; on Evolution, 1908, 65, 85-8
126 THE VALUE OF COLOUR
Review! and an account of it is to be found in the
Origin’ and in the Descent of Man.*
Darwin continually writes of the value of
hypothesis as the inspiration of inquiry. We find
an example in his letter to Bates, Nov. 22, 1860:
‘T have an old belief that a good observer really
means a good theorist, and I fully expect to find
your observations most valuable.’ Darwin’s
letter refers to many problems upon which Bates
had theorized and observed, but as regards
Mimicry itself, the hypothesis was thought out
after his return home from the Amazons, when
he no longer had the opportunity of testing it by
the observation of living Nature. It is by no
means improbable that, had he been able to apply
this test, Bates would have recognized that his
division of butterfly resemblances into two
classes—one due to the theory of Mimicry, the
other to the influence of local conditions—could
not be sustained.
Fritz Miiller’s contributions to the problem of
Mimicry were all made in S.E. Brazil, and
numbers of them were communicated, with other
observations on natural history, to Darwin, and
by him sent to Professor R. Meldola who
published many of the facts. Darwin’s letters to
Meldola*® contain abundant proofs of his interest
in Miller's work upon Mimicry. One deeply
1 New Ser., iii. 1863, 219. * Ed. 1872, 375-8.
3 Ed. 1874, 323-5. * More Letters, i. 176.
5 Poulton, Charles Darwin and the theory of Natural Selection,
Lond. (1896), 199-218.
SEXUAL VERSUS NATURAL SELECTION 127
interesting letter’ dated Jan. 28, 1872, proves
that Fritz Miller before he originated the theory
of Common Warning Colours (Synaposematic
Resemblance or Miillerian Mimicry), which will
ever be associated with his name, had conceived
the idea of the production of mimetic likeness by
Sexual Selection.
Darwin’s letter to Meldola shows that he was
by no means inclined to dismiss the suggestion as
worthless, although he considered it daring.
‘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.’ *
A little later, on April 5, he wrote to Professor
August Weismann on the same subject :—
‘It may be suspected that even the habit of viewing
differently coloured surrounding objects would influence
their taste, and Fritz Miller even goes so far as to believe
that the sight of gaudy butterflies might influence the taste
of distinct species.’*®
This remarkable suggestion affords interesting
evidence that F. Miller was not satisfied with
the sufficiency of Bates’s theory. Nor is this
surprising when we think of the numbers of
; ‘aces. Lad 202.
: wrote, Aug. 2, 1871, in very similar terms to Fritz Miller
himself. Life and Letters, iii. 151. * Life and Letters, iii. 157.
128 THE VALUE OF COLOUR
abundant conspicuous butterflies which he saw
exhibiting mimetic likenesses. The common
instances in his locality, and indeed everywhere
in tropical America, were anything but the hard-
pressed struggling forms assumed by the theory
of Bates. They belonged to the groups which
were themselves mimicked by other butterflies.
Fritz Miller’s suggestion also shows that he did
not accept Bates’s alternative explanation of a
superficial likeness between models themselves,
based on some unknown influence of local physico-
chemical forces. At the same time Miiller’s own
suggestion was subject to this apparently fatal
objection, that the Sexual Selection he invoked
would tend to produce resemblances in the males
rather than the females, while it is well known
that when the sexes differ the females are almost
invariably more perfectly mimetic than the males
and in a high proportion of cases are mimetic
while the males are non-mimetic. 7
The difficulty was met several years later by
Fritz Miller’s well-known theory, published in
1879,! and immediately translated by Meldola
and brought before the Entomological Society.’
Darwin’s letter to Meldola dated June 6, 1879,
shows ‘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
’ Kosmos, May, 1879, 100. ® Proc. Ent. Soc. Lond., 1879, xx.
en bie 2” oe
¥
MELDOLA AND MULLER’S THEORY 129
and to find the means for its presentation to
English naturalists.’ Of the hypothesis itself
Darwin wrote, ‘F. Miiller’s view of the mutual
protection was quite new to me.’* The hypothesis
of Miillerian Mimicry was at first strongly
opposed. Bates himself could never make up his
mind to accept it. As the Fellows were walking
out of the meeting at which Professor Meldola
explained the hypothesis, an eminent entomolo-
gist, now deceased, was heard to say to Bates:
‘It’s a case of save me from my friends!’ The
new ideas encountered and still encounter to a
great extent the difficulty that the theory of
. Bates had so completely penetrated the literature
of natural history. The present writer has
observed that naturalists who have not thoroughly
absorbed the older hypothesis are usually far
more impressed by the newer one than are those
whose allegiance has already been rendered. The
acceptance of Natural Selection itself was at first
hindered by similar causes, as Darwin clearly
recognized :—
‘If you argue about the non-acceptance of Natural
Selection, it seems to me a very striking fact that the New-
tonian theory of gravitation, which seems to every one now so
certain and plain, was rejected by a man so extraordinarily
able as Leibnitz. The truth will not penetrate a preoccupied
mind. 23 .
y Sora Dorwie and the theory of Natural Selection, 214.
* To Sir J. Hooker, July 28, 1868, More Letters, i. 305. See also
the letter to A. R. Wallace, April 30, 1868, in More Letters, ii. 77,
lines 6-8 from top.
K
130 THE VALUE OF COLOUR
There are many naturalists, especially students
of insects, who appear to entertain an inveterate
hostility to any theory of Mimicry. Some. of
them are eager investigators in the fascinating
field of geographical distribution, so essential for
the study of Mimicry itself. The changes of
pattern undergone by a species of Hrebia as we
follow it over different parts of the mountain
ranges of Europe is indeed a most interesting
inquiry, but not more so than the differences
between e.g. the Acraea johnstoni of S.E. Rhodesia
and of Kilimanjaro. A naturalist who is interested
by the Evebia should be equally interested by the
Acraea; and so he would be if the student of
Mimicry did not also record that the characteristics
which distinguish the northern from the southern
individuals of the African species correspond with
the presence, in the north but not in the south,
of certain entirely different butterflies, That
this additional information should so greatly
weaken, in certain minds, the appeal of a
favourite study, is a psychological problem of
no little interest. This curious antagénism is
I believe confined to a few students of insects.
Those naturalists who, standing rather farther off,
are able to see the bearings of the subject more
clearly, will usually admit the general support
yielded by an ever-growing mass of observations
to the theories of Mimicry propounded by
H. W. Bates and Fritz Miller, In like manner
Natural Selection itself was in the early days
;
PREJUDICE AGAINST MIMICRY 181
often best understood and most readily accepted
by those who were not naturalists. Thus Darwin
wrote to D. T. Ansted, Oct. 27, 1860 :—
‘I am often in despair in making the generality of
naturalists even comprehend me. Intelligent men who are
not naturalists and have not a bigoted idea of the term
species, show more clearness of mind.’ !
Even before the Origin appeared Darwin
anticipated the first results upon the mind of
naturalists. He wrote to Asa Gray, Dec. 21,
1859 :—
‘I have made up my mind to be well abused; but I
think it of importance that my notions should be read by
intelligent men, accustomed to scientific argument, though
not naturalists. It may seem absurd, but I think such men
will drag after them those naturalists who have too firmly
fixed in their heads that a species is an entity.’’
Mimicry was not only one of the first great
departments of zoological knowledge to be studied
under the inspiration of Natural Selection, it is
still and will always remain one of the most
interesting and important of subjects in relation
to this theory as well as to evolution. In Mimicry
we investigate the effect of environment in its
simplest form: we trace the effects of the
pattern of a single species upon that of another
far removed from it in the scale of classification.
When there is reason to believe that the model
is an invader from another region and has only
recently become an element in the environment
» More Letters, i, 175.
2 Life and Letters, ii. 245, See also pp. 32-3 of the present work.
K 2
182 THE VALUE OF COLOUR
of the species native to its second home, the
problem gains a special interest and fascination."
We are chiefly dealing with the fleeting and
changeable element of colour, and we expect to
find and we do find evidence of a comparatively
rapid evolution. The invasion of a fresh model
is for certain species an unusually sudden change
in the forces of the environment, and in some
instances we have grounds for the belief that the
mimetic response has not been long delayed.
MIMICRY AND SEX
Ever since Wallace’s classical memoir on
Mimicry in the Malayan swallow-tail butterflies,
those naturalists who have written on the subject
have followed his interpretation of the marked
prevalence of mimetic resemblance in the female
sex as compared with the male. They have
believed with Wallace that the greater dangers of
the female, with slower flight and often alighting
for oviposition, have been in part met by the high
development of this special mode of protection.
The fact cannot be doubted. It is extremely
common for a non-mimetic male to be accom-
panied by a beautifully mimetic female and often
by two or three different forms of female, each
mimicking a different model. Indeed in these
latter cases the male is usually non-mimetic
(e. g. Papilio dardanus=merope), or if a mimic
1 See pp. 159-77, which are devoted to the detailed considera-
tion of an example of this kind.
Yr
WALLACE AND FEMALE MIMICRY 188
(e.g. the Nymphaline genus Ewripus) resembles
a very different model. On the other hand, a
non-mimetic female accompanied by a mimetic
male is excessively rare. An example is afforded
by the Oriental Nymphaline, Cethosia, in which
the males of some species are rough mimics of
the brown Danaines. When both sexes mimic, it
is very common for the females to be better and
often far better mimics than the males.
Predominant female Mimicry is character-
istic of butterflies and very rare in moths. If
examples occur at all among the numberless
mimetic Diptera, Coleoptera, &c., they are
probably excessively scarce. In some of the orb-
weaving spiders, however, the males mimic ants,
while the much larger females are non-mimetic.
Although still believing that Wallace’s
hypothesis in large part accounts for the facts
briefly summarized above, the present writer has
recently been led to doubt whether it offers a
complete explanation. Mimicry in the male,
even though less beneficial to the species than
Mimicry in the female, would still surely be
advantageous. Why then is it so often entirely
restricted to the female? While the attempt to
find an answer to this question was haunting
me, I re-read a letter written-by Darwin to
Wallace, April 15, 1868, containing the following
sentences :—
‘When female butterflies are more brilliant than their
males you believe that they have in most cases, or in all
134 THE VALUE OF COLOUR
cases, been rendered brilliant so as to mimic some other
species, and thus escape danger. But can you account for
the males not having been rendered equally brilliant and
equally protected? Although it may be most for the
welfare of the species that the female should be protected,
yet it would be some advantage, certainly no disadvantage,
for the unfortunate male to enjoy an equal immunity from
danger. For my part, I should say that the female alone
had happened to vary in the right manner, and that the
beneficial variations had been transmitted to the same sex
alone. Believing in this. I can see no improbability (but
from analogy of domestic animals a strong probability) that
variations leading to beauty must often have occurred in the
males alone, and been transmitted to that sex alone. ThusI
should account in many cases for the greater beauty of the male
over the female, without the need of the protective principle.’
The consideration of the facts of Mimicry thus led
Darwin to the conclusion that the female happens
to vary in the right manner more commonly than
the male, while the secondary sexual characters of
males supported the conviction ‘that from some
unknown cause such characters [viz. new charac-
ters arising in one sex and transmitted to it alone}
apparently appear oftener in the male than in the
female ’.”
Comparing these conflicting arguments, we are
* More Letters, ii. 73, 74. On the same subject—‘the gay-
coloured females of Pieris’ (Perrhybris (Mylothris) pyrrha of Brazil),
Darwin wrote to Wallace, May 5, 1868, as follows: ‘1 believe
I quite follow you in believing that the colours are wholly due
to mimicry ; and I further believe that the male is not brilliant
from not having received through inheritance colour from the
female, and from not himself having varied; in short, that he has
not been influenced by selection.’ It should be noted that the
male of this species does exhibit a mimetic pattern on the under
surface.—More Letters, ii. 78.
* Letter from Darwin to Wallace, May 5, 1867, More Letters,
ii. 61.
——— =
DARWIN AND FEMALE MIMICRY 135
led to believe that the first is the stronger.
Mimicry in the male would be no disadvantage
but an advantage, and when it appears would be
and is taken advantage of by selection. The
secondary sexual characters of males would be no
advantage but a disadvantage to females, and, as
Wallace thinks, are withheld from this sex by
selection. It is indeed possible that Mimicry has
been hindered and often prevented from passing
to the males by Sexual Selection. We know that
Darwin was much impressed! by Thomas Belt’s
daring and brilliant suggestion that the white
patches which exist, although ordinarily concealed,
on the wings of mimetic males of certain Pierinae
(Dismorphia), have been preserved by preferential
mating. He supposed this result to have been
brought about by the females exhibiting a deep-
seated preference for males that displayed the
chief ancestral colour, inherited from periods
before any mimetic pattern had been evolved in
the species. But it has always appeared to me
that Belt’s deeply interesting suggestion requires
much solid evidence and repeated confirmation
before it can be accepted as a valid interpretation
of the facts.
In the present state of our knowledge, at any rate
of insects and especially of Lepidoptera, it is pro-
bable that the female is more apt to vary than the
male, and that an important element in the inter-
pretation of prevalent female Mimicry is provided
? Descent of Man, 325.
136 THE VALUE OF COLOUR
by this fact. In order adequately to discuss the
-question of Mimicry and sex it would be necessary
to analyse the whole of the facts, so far as they
are known in butterflies, On the present occasion
it is only possible to state the inferences which
haye been drawn from general impressions—in-
ferences which it is believed will be sustained by
future detailed inquiry.
(1) Mimicry may occasionally arise. in one sex
because the differences which distinguish it from
the other sex happen to be such as to afford
a starting-point for the resemblance. Here the
male is at no disadvantage as compared with
the female, and the rarity of Mimicry in the.
male .alone (e.g. Cethosia) is evidence that the
great predominance of female Mimicry. is not
to be thus explained. .
(2) The greater colour-variability of the female,
observed at least in certain groups of butterflies,
and especially her more pronounced tendency
to dimorphism and polymorphism, have been
of much importance in determining this pre-
dominance. Thus if the female appear'in two
different forms and the male in only one, it ‘will
be twice as probable that she will happen to
possess a sufficient foundation for the evolution
of Mimicry.
(3) The appearance of melanic or partially
melanic forms in the female has been of very
great service, providing as it does a change of
ground-colour. Thus the Mimicry of the black
1 Suche
CONCLUSIONS ON MIMICRY AND SEX 1387
generally red-marked American ‘ Aristolochia
swallow-tails’ (Pharmacophagus) by the females of
Papilio swallow-tails was probably begun in this
way.
(4) It is probably incorrect to assume with
Haase that Mimicry always arose in the female
and was later acquired by the male. Both sexes
of the third section of swallow-tails (Cosmodesmus)
mimic Pharmacophagus in America, far more per-
fectly than do the females of Papilio. But this
is not due to Cosmodesmus presenting us with
a later stage of the history begun in Papilio; for
in Africa Cosmodesmus is still mimetic (of Danainae)
in both sexes although the resemblances attained
are imperfect, while many African species of
Papilio have non-mimetic males with beautifully
mimetic females. The explanation is probably
to be sought in the fact that the females of
Papilio are more variable and more often tend
to become dimorphic than those of Cosmodesmus,
while the latter group has more often happened
to possess a sufficient foundation for the origin
of the resemblance, in patterns which, from the
start, were common to male and female.
(5) In very variable species with sexes alike,
Mimicry can be rapidly evolved in both sexes
out of very small beginnings. Thus the reddish
marks which are common in many individuals
of Limenitis arthemis were almost certainly the
starting-point for the evolution of the beautifully
mimetic L. archippus. Nevertheless in such
138 THE VALUE OF COLOUR
cases, although there is no reason to suspect
any greater variability, the female is commonly
a somewhat better mimic than the male and
often a very much better mimic. Wallace’s
principle seems here to supply the obvious in-
terpretation ; but it is to be noted that the evo-
lution of Mimicry is taking place in colours that
are associated with sex. Otherwise, it is impos-
sible to explain the fact that the more perfect
Mimicry attained by one sex is not immediately
transferred to the other.
(6) When the difference between the patterns
of model and presumed ancestor of mimic is very
great, the female is often alone mimetic; when
the difference is comparatively small, both sexes
are commonly mimetic. The Nymphaline genus
Hypolimnas is a good example. In Hypolimnas
itself the females mimic Danainae with patterns
very different from those preserved by the non-
mimetic males: in the sub-genus EHuralia, both
sexes resemble the black and white Ethiopian
Danaines with patterns not very dissimilar from
that which we infer to have existed in the non-
mimetic ancestor.
(7) Although a melanic form or other large
variation may be of the utmost importance in
facilitating the start of a mimetic likeness, it is
impossible to explain the evolution of any detailed
resemblance in this manner. And even the
large colour variation itself may well be the
expression of a minute and ‘continuous’ change
CONCLUSIONS ON MIMICRY AND SEX 189
in the chemical and physical constitution of pig-
ments.
(8) Female Mimicry is not by any means always
a question of colour and pattern alone, Thus,
the mimetic females of some Papilionidae lose the
‘tails’ which are retained by the non-mimetic
males (e.g. P. dardanus = merope), and the females
of the tropical American Nymphaline genus
Eresia and Pierine genus Dismorphia and _ its
allies, are not only better mimics in colour and
pattern but also in shape of the wings.
SEXUAL SELECTION (EPIGAMIC CHARACTERS)
We do not know the date at which the idea
of Sexual Selection arose in Darwin’s mind, but
it was probably not many years after the ‘sudden
flash of insight’ which, in October, 1838, gave to
him the theory of Natural Selection. An excel-
lent account of Sexual Selection occupies the
concluding paragraph of Part I of Darwin's
Section of the Joint Essay on Natural Selection,
read July 1, 1858, before the Linnean Society.'
The principles are so clearly and sufficiently
stated in these brief sentences that it is appro-
priate to quote the whole :
‘Besides this natural means of selection, by which those
individuals are preserved, whether in their egg, or larval, or
mature state, which are best adapted to the place they fill in
nature, there is a second agency at work in most unisexual
animals, tending to produce the same effect, namely, the
struggle of the males for the females. These struggles are
? Journ. Proc. Linn. Soe., iii. 1859, 50.
140 THE VALUE OF COLOUR
generally decided by the law of battle, but in the case of
birds, apparently, by the charms of their song, by their
beauty or their power of courtship, as in the dancing rock-
thrush of Guiana. The most vigorous and healthy males,
implying perfect adaptation, must generally gain the victory
in their contests. This kind of selection, however, is less
rigorous 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 result of this struggle amongst the males
may be compared in some respects to that produced by those
agriculturists who pay less attention to the careful selection
of all their young animals, and more to the occasional use of
a choice mate.’
A full exposition of Sexual Selection appeared
in the Descent of Man in 1871, and in the greatly
augmented second edition, in 1874. It has been
remarked that the two subjects, The Descent of
Man and Selection in Relation to Sex, seem to
fuse somewhat imperfectly into the single work
of which they form the title. The reason for
their association is clearly shown in a letter to
Wallace, dated May 28, 1864: ‘... I suspect that
a sort of sexual selection has been the most
powerful means of changing the races of man.’ !
Darwin, as we know from his Autobiography,?
was always greatly interested in this hypothesis,
and it has been shown in the preceding pages
that he was inclined to look favourably upon it
1 More Letters, ii. 33. 2 Life and Letters, i. 94.
DARWIN AND SEXUAL SELECTION 141
as an interpretation of many appearances usually
explained by Natural Selection. Hence Sexual
Selection, incidentally discussed in other sections
of the present essay, need not be considered at
any length, in the section specially allotted to it.
Although so interested in the subject and not-
withstanding his conviction that the hypothesis
was sound, Darwin was quite aware that it was
probably the most vulnerable part of the Origin.
Thus he wrote to H. W. Bates, April 4, 1861 :—
‘If I had to cut up myself in a review I would have
[ worried ?] and quizzed sexual selection; therefore, though
I am fully convinced that it is largely true, you may imagine
how pleased I am at what you say on your belief.’’
The existence of sound-producing organs in
the males of insects was, Darwin considered,
the strongest evidence in favour of the operation
of Sexual Selection in this group.? Such a con-
clusion has received strong support in recent
years by the numerous careful observations of
Dr. F. A. Dixey* and Dr. G. B. Longstaff* on
the scents of male butterflies. The experience
of these naturalists abundantly confirms and ex-
tends the account given by Fritz Miller® of the
scents of certain Brazilian butterflies. It is a
remarkable fact that the apparently epigamic
scents of male butterflies should be pleasing to
? More Letters, i. 183. 2 Life and Letters, iii. 94, 138.
® Proc. Ent. Soc, Lond., 1904, lvi.; 1905, xxxvii., liv. ; 1906, ii.
* Proc. Ent. Soc. Lond., 1905, xxxv.; Trans. Ent, Soc. Lond., 1905,
136; 1908, 607.
6 Jen, Zeit., xi., 1877, 99; Trans. Ent. Soc. Lond., 1878, 211.
142 THE VALUE OF COLOUR
man while the apparently aposematic scents in
both sexes of species with warning colours should
be displeasing to him. But the former is far
more surprising than the latter. It is not per-
haps astonishing that a scent which is ex hypothesi
unpleasant to an insect-eating Vertebrate should
be displeasing to the human sense; but it is
certainly wonderful that an odour which is ex
hypothesi agreeable to a female butterfly should
also be agreeable to man.
Entirely new light upon the seasonal appear-
ance of epigamic characters is shed by the recent
researches of C. W. Beebe,’ who caused the
scarlet tanager (Piranga erythromelas) and the
bobolink (Dolichonyx oryzivorus) to retain their
breeding plumage through the whole year by
means of fattening food, dim illumination and
reduced activity. Gradual restoration to the
light and the addition of meal-worms to the diet
invariably brought back the spring song, even
in the middle of winter. A sudden alteration
of temperature, either higher or lower, caused
the birds nearly to stop feeding, and one tanager
lost weight rapidly and in two weeks moulted
into the olive green winter plumage. After a
year, and at the beginning of the normal breeding
season, ‘individual tanagers and bobolinks were
gradually brought under normal conditions and
activities,’ and in every case moulted from nuptial
plumage to nuptial plumage. ‘The dull colors of.
1 The American Naturalist, xlii. No. 498, Jan, 1908, 34.
— — =
. u |
CONTROL OF NUPTIAL PLUMAGE 148
the winter season had been skipped.’ The author
justly claims to have established ‘that the se-
quence of plumage in these birds is not in any
way predestined through inheritance...... , but
that it may be interrupted by certain factors in
the environmental complex ’.
Mr. Beebe’s deeply interesting investigations on
birds prove that external stimulus may be as
necessary for the production of the tints displayed
in courtship as for other colours that are character-
istic of the species (p. 110). Birds may thus exhibit
the individual susceptibility to environment so
well known in numbers of insect larvae and pupae
(p. 109). Although certain naturalists, especially
the students of plant oecology,' consider that re-
sults of this kind are opposed to a Darwinian
interpretation, it is perfectly clear that ‘the
changes so produced must, like any other varia-
tions, pass through the ordeal of the survival of
the fittest’.2 And when each possible response
is appropriate to the special environment which
provides the stimulus, it is obvious that, so far
from witnessing the elimination of Natural Selec-
tion, we are in presence of its highest manifesta-
tion.
See J. M. Coulter in Fifty Years of es psts a New York,
1909, 61-3
s Editors of More Letters, i, 214 n. 1.
VI
MIMICRY IN THE BUTTERFLIES OF
NORTH AMERICA
Written from the notes of the Anniversary Address de-
livered to the Entomological Society of America, Baltimore,
Thursday, December 31, 1908.
INTRODUCTORY
Wirtuin a few weeks of the hundredth anni-
versary of Darwin’s birth, and nearly midway
between the fiftieth anniversaries of the publica-
tion of Natural Selection on July 1 last and the
Origin of Species on Nov. 24 next, it seemed to me
specially appropriate to select for this address
a subject that is closely associated with Darwinian
teachings. Although he did not publish it during
his lifetime, we now know from his correspond-
ence that Darwin independently originated the
interpretation of Mimicry which was afterwards
suggested by H. W. Bates.' Its development
in the mind of the naturalist of the Amazons and
the rival theory afterwards suggested by Fritz
Miiller, were both of them the direct outcome, in
Bates’s case the very speedy outcome, of the Origin.
The deep interest which Darwin took in the
1 See pp. 128-4.
a “a
MIMICRY AND EVOLUTION 145
hypotheses of both naturalists is proved by many
a letter in his published correspondence." All
this forms a peculiarly fascinating chapter of
ancient history,—nevertheless ancient history ;
but if we desire to choose a subject because of the
light it can throw to-day and is certain to throw
to-morrow upon evolution and its causes, there is
no study which for promise as well as performance
can be set on a higher level than Mimicry.
In the course of the following address the word
‘Mimicry’ will be used with the restricted mean-
ing attached to it by A. R. Wallace. It will
be applied solely to the superficial resemblances _
between animals, and not to their likeness to
vegetable or mineral surroundings for the purpose
of concealment.
The study of Mimicry is of the highest value in
relation to_both evolution itself and the motive
causes of evolution.
Apart from all question of the means by which
Mimicry has been produced, it will be generally
admitted that the mimetic species has in some
way evolved a superficial resemblance to the
pattern of one or more species, more or less
remote from it in the scale of classification.
Looking on the changes by which the resem-
blance has been produced as a piece of evolu-
tionary history, and, as I have said, disregarding
for the moment their causes, we have one of the
1 See pp. 123-9.
L
146 MIMICRY IN N. AMERICAN BUTTERFLIES
very simplest and sharpest pictures of organic
transformation presented for our investigation.
An effect—generally a strongly marked and con-
spicuous effect—has been brought about in those
elements which make up the superficial appear-
ance of a species, and this important change is
manifestly in the direction of only a minute
fraction of the infinitely complex organic environ-
ment, viz. that fraction contributed by the super-
ficial appearance of one or more very different
species, commonly indeed of but a single one.
When, as in North America, a recent invader
becomes the model determining the direction of
evolution in some constituent of the ancient
butterfly fauna, the case becomes especially
striking.
The effects produced on the mimic are
generally sharper and more distinct than those
seen in the concealing resemblances to bark,
lichen, earth, &c.,—the difference corresponding
to the more definite and individual appearance
usually presented by the pattern of the model
as compared with such elements in the vegetable
and mineral surroundings. There are also other
important differences. The models of Mimicry
are generally more restricted in -their range,
and differ more widely in different areas and in
different parts of the same area than the models
of cryptic resemblance. Differences between the
local forms of the same model imply that the
mimicked species has itself been subject to rapid
MIMETIC AND CRYPTIC COLOURS 147
change, while the models of cryptic resemblance
appear by comparison to be stereotyped and
permanent. Furthermore the models as well as
their mimics within the same area are liable to
changes of distribution, whereas the models of
cryptic resemblance are as a rule comparatively
fixed. A mimetic species may often be found
passing into an area where its model exists in
a different form or does not exist at all, and
highly instructive conclusions may be drawn
from the study of the corresponding changes.
In accordance with the facts briefly summarized
in the above statements, we find that better and
more numerous examples of rapid recent change
are to be found in mimetic patterns than in those
which promote concealment. Not only is this
evident when we trace the geographical changes
of model and mimic over a wide continuous
area, but in many cases the same genus includes
both mimetic and non-mimetic species, the latter
enabling us to infer with more or less certainty
the ancestral appearance of the former. The
history thus unravelled may often be further
confirmed by a study of the non-mimetic males
of mimetic females.
Many naturalists at the present day incline to
return to the old belief that the history of evolu-
tion has been ‘discontinuous’, proceeding by
‘ mutations ’ or large and definite steps of change.
The comprehensive and detailed study of Mimicry
as a piece of biological history certainly provides
L2
148 MIMICRY IN N. AMERICAN BUTTERFLIES
one of the best and safest means—perhaps the
very best—of forming a judgement between this
revived opinion and Darwin’s conclusion that,
although the rate of transformation varied greatly
and might slow down to nothing for long periods,
the steps of change were small, forming a gradual
and ‘ continuous ’ transition between the successive
forms in the same evolutionary history.!
The study of the causes of Mimicry is more
difficult than that of the history of Mimicry, the
conclusions far less\certain. Nevertheless the
evidence at present available yields much support
to the theory of Natural Selecti
cause of evolutio facts certainly do not
0 any other interpretation. They negative
aa ceeertaea grea mag eee have
been—produced—by—the_ on of external
forees—(Hypothesis of External Causes)—or—by
varia selection (Hypothesis of In-
ternal Causes). Nor do they support Fritz Miller’s
earlier and daring speculation (see pp. 127-8)
that female preferences were influenced by the
sight of the patterns displayed by the models
(Hypothesis of Sexual Selection). The -only.
hypotheses -which—are in any way consistent with
the body of fac, considered a's Wil, are those
which assume that the resemblances in question
have been_built- up by the selection-of-variations
beneficial in the struggle-for life.
In its concentration on a minute fraction of the
1 See pp. 42-51; also Appendix B, p. 254.
SUGGESTED CAUSES OF MIMICRY 149
total organism as well as in the rapidity of the
results achieved, the operation of Natural Selection
in the production of Mimicry is more than ordi-
narily akin to the methods of Artificial Selection.
Indeed a very fascinating and promising line
of investigation in a suitable locality would be
the attempt to initiate or improve a mimetic
likeness by means of Artificial Selection.
Mimetic resemblances are of two kinds, re-
spectively interpreted by two well-known hypo-
theses, both based on the theory of Natural
Selection.
1. Mimicry as interpreted by H. W. Bates
is an advantageous deceptive resemblance borne
by palatable or harmless species (the mimics) to
others that are unpalatable or otherwise specially
defended (the models’. Such resemblance will
be spoken of as Batesian Mimicry, the examples
as Batesian mimics, the interpretation as the
Batesian Hypothesis.
2. The resemblances.between specially defended
species themselves, although well known to Bates,
were not explained by his hypothesis as he con-
ceived it. He suggested that they were an
expression of the common results produced by
forces common to the environment of the species
in question. Such likenesses! were subsequently
interpreted by Fritz Miller as the advantageous
adoption of a common advertisement by specially
' It is
Miller had
Selection.
robable that these were the examples which Fritz
igang | sought to explain by the theory of Sexual
e pp. 127-8 of the present volume.
150 MIMICRY IN N. AMERICAN BUTTERFLIES
defended species, whereby the loss of life incurred
during the education of young inexperienced
enemies was contributed between the similar
forms, instead of by each species independently
as would have been the case if they had been
dissimilar, and possessed patterns requiring each
a separate education. Such resemblance will be
spoken of as Miillerian Mimicry, the examples as
Miillerian mimics, the interpretation as the Mil-
lerian Hypothesis.
SPECIAL ADVANTAGES OF THE NORTH
AMERICAN BUTTERFLY FAUNA FOR
THE STUDY OF MIMICRY
The butterfly fauna of North America affords
probably the best field in which to begin the
study of Mimicry,—-a subject which has been
shown to possess the most profound significance
in relation to the deepest problems by which the
naturalist is confronted. The examples are sharp
and striking, but not too numerous, and the
inquiry can be approached without the confusion
and excessive strain on the memory which must
inevitably at first beset the student of Mimicry in
the tropics. But outside the tropics it is also. the
best field for this study, as will be shown below.
The western section of the Palaearctic Region is
sharply cut off by the Sahara from the Ethiopian,
and its few examples of Mimicry are not such
as would be likely to awaken the interest and
enthusiasm of the beginner. The eastern Palae-
SPECIAL ADVANTAGES OF N. AMERICA 151
arctic section suffers from the opposite defect.
Separated by imperfect barriers from the Oriental
Region, its butterfly fauna is complicated by
much invasion of specially protected species from
the tropics, and the examples of Mimicry are too
numerous and too little known. North America
oceupies a position conveniently intermediate
between the two sections of the Palaearctic por-
tion of the circumpolar land-belt. It has been
invaded by models from the eastern tropics of
the Old World and also probably from the tropics
of the New; but the species are few and their
effects upon the indigenous butterflies sharp and
distinct. The Mimicry itself affords striking and
remarkable evidence of the lines of migration
followed by some of the intruding models. The
ancestral forms from which the mimics were
derived, have nearly always persisted, and enable
us to unravel the history of the change, with
exceptional clearness. The examples bear in a
most interesting manner upon the two great
hypotheses associated respectively with the names
of H. W. Bates and Fritz Miller. Although the
butterfly fauna is as well known as that of any
part of the world, the mimetic resemblances
supply material for a large amount of much-
needed original investigation, inviting the atten-
tion of American naturalists in almost every
locality.
152 MIMICRY IN N. AMERICAN BUTTERFLIES
THE DANAINE MODELS OF NORTH AMERICA,
AND THEIR RELATIONSHIP TO THE SOUTH
AMERICAN AND OLD WORLD DANAINAE!
The Danainae are the most important and most
extensively mimicked of all specially protected
butterflies in the Old World tropics. The Acraei-
mae, so abundant in Africa, are also greatly
mimicked, but to a far less extent than the com-
paratively few species of Danainae found in the
same Region, —allbelonging to the section Danaini.
The Ethiopian Acraeas in fact supply several
mimics of the Danaines, but no example of the
opposite relationship is known. In the tropical
East, the Acraeinae are poorly represented, while
the Danainae (Danaini, Euploeini, Hestia, Hama-
dryas) are dominant in numbers as well as in the
power of influencing the patterns of other butter-
fly groups. In both Africa and the East, Mil-
1 The subject of the address from this point onwards is treated
in considerable detail in the author’s memoir, Mimetic North
American species of the Genus Limenitis (s.1.) and their models,
in Trans. Ent. Soc. Lond., 1908, 447-88. Dr. Jordan’s later con-
clusions as to the affinities of Danaida plexippus, added to the
memoir in a terminal note (488) and somewhat at variance with
his earlier conclusions quoted in the text, are here adopted
throughout. A broader and less detailed treatment is followed
in this address, special attention being directed to the numerous
points on which further observations are required. Where no
other authority is mentioned I have followed the synonymy and
geographical distribution of Scudder’s great work, Butterflies of
the Eastern United States and Canada, and, for the Papilionidae,
Rothschild and Jordan's fine monograph (Nov. Zool., xiii, 1906,
411-752). I have not, however, followed Scudder in the general
use of Basilarchia as a generic name, because I think that the
whole group of Limenitis, in its widest acceptation, requires revision,
and that until this has been accomplished it is inexpedient to
adopt the terminology proposed for a portion of it.
:
|
;
THE WORLD MODELS FOR MIMICRY 158
lerian Mimicry is evident between the different
genera and sections of the specially protected
groups themselves.
In the richest and most remarkable butterfly
fauna in the world, that of South America, the
dominant specially protected group is composed
of the Ithomiinae, allied to the Danainae, and
called by Bates ‘ Danaoid Heliconidae’. Next in
importance come the Heliconinae, allied to the
Acraeinae, and called by Bates ‘ Acraeoid Heli-
conidae ’’. Both of these are extensively mimicked,
especially the Ithomiinae : in fact it was the close
and obvious Mimicry of these by certain species of
the Heliconinae that puzzled Bates and ultimately
received an interpretation in the Miillerian Hy-
pothesis. In addition to the above, this rich and
varied Region contains numerous true Acraeinae,
mimicked considerably, and a small number of
true Danaine species. These latter, which are of
extreme interest, fall into two groups. One of
them, the Lycoraeini, containing the two genera
Lycorea and Ituna, is confined to South America,
and bears evident traces of long residence in the
Region. The whole of the species are mimetic of
various dominant Ithomiine genera, while at the
same time some of them appear also to act as
models for other butterflies, in a single case
(Ituna phenarete) even for one of the rarer species
(Eutresis imitatriz) belonging to the Ithomiinae
themselves. It was the resemblance between
the Lycoraeine genus Jtuna and the Ithomiine
154 MIMICRY IN N. AMERICAN BUTTERFLIES
genus Thyridia that led Fritz Miller to his
hypothesis, and formed the title of the paper
in which he first expounded it. The Lycoraeini
are widely different from any of the Old World
Danainae and are sometimes separated from them
as a distinct sub-family. The second group of
Danaines, found in North America as well as
South, belongs to the Old World section Danaini,
and is in every respect strongly contrasted with
the Lycoraeini. Its species, divided into two
genera Anosia and Tusitia by Moore, are not
known to enter into mimetic relations with any
of the other butterflies of this southern Region.’
Furthermore, they not only belong to a dominant
Old World section of the Danaines, but are even
closely allied to particular species within it. It
is probable that there are only two well-marked
species of Danaini on the American Continent,
and that the various forms encountered over this
vast area are the geographical races or sub-species
of these two. In north temperate America they
are the well-known models for mimicry,—Anosia
plexippus extending far into Canada, and Tasitia
berenice and its form strigosa not ranging beyond
the southern States,
In 1897, at the Detroit meeting of the American
Association for the Advancement of Science, I
suggested * that the Mimicry of Anosia plexippus
‘ It is possible, however, that there are incipient resemblances
to Anosia in certain 8. American Acraeinae.
* Proc. Am, Assoc, Adv. Sci., 1897, xlvi. 244.
- > ae a ™ »
—e. > = ul
r t iv .
4 }
HISTORY INFERRED FROM MIMICRY 155
by Limenitis (Basilarchia) archippus was evidence
that the model had long resided in North
America, and that we might on this ground alone,
even if we had not abundant positive evidence of
its gradually increasing spread in the Old World
during the past half-century, infer that Anosia
had reached Fiji, Australia, Hong-Kong, &c., in
comparatively recent times. This conclusion can
hardly be doubted, and the argument might have
been extended to enable us to infer the ancestral
line of migration by which North America itself
had been reached by this form. But in 1897 I
followed what appeared to be the general view,
that, in the New World, the original stream of
Danaine invasion had run from the American
tropics northward,' nor did I observe that the
evidence based on the growth of mimetic resem-
blance warranted the interesting conclusion that
its flow had taken the opposite direction, and
that the south had been peopled by way of the
north. Accepting this conclusion the question
arises: Whence came the Danaini of North
America? The answer requires a somewhat
careful comparison between the New and Old
World butterflies of this group.
Among the commonest of the Old World
Danaini, are certain species with tawny colouring,
a black border, and black white-barred apex to
the fore wing. The under surface is even more
* Verhandl. d. V. Internat. Zool. Congr. z. Berlin, 1901, Jena,
1902, 171. See also Essays on Evolution (1908), 274: also errata.
156 MIMICRY IN N. AMERICAN BUTTERFLIES
conspicuous than the upper, being brighter in
colour and the black border marked with white
in a more striking manner. In one set of
Oriental species, placed by Moore in his genus
Salatura, the veins are heavily marked with black
on both surfaces, conferring a very characteristic
appearance, especially upon the hind wing. The
other set of species in which the veins are com-
paratively inconspicuous is placed by Moore in
LTimnas, including L. chrysippus, perhaps the
commonest butterfly in the world, ranging from
the Cape to Hong-Kong and perhaps to Japan.
It is clear, however, that Africa is its ancestral
home; for it is there mimicked far more exten-
sively than in any other country.!_ In the Malay
Archipelago, both Salatura and Limnas are repre-
sented by various forms, and in some of these
the tawny colouring becomes much darkened.
This tendency appears to be more frequent in
Limnas, and when both forms have darkened in.
the same island (e.g. Java) it is probable that
Limnas has acted as the model for Salatura. There
is a close general resemblance in colouring and
pattern between Salatura of the Old World and
Anosia of the New, as also between Limnas of the
Old World and Tasitia of the New. Furthermore
the two New World species differ from each other
in the same points as do those of the Old. The
dark, white-barred apex of the fore wing, so
conspicuous in the Old World forms, is less
1 Proc. Am. Assoc. Adv. Sci., 1. ¢., 244.
NEW AND OLD WORLD DANAIDAS 157
emphasized in those of the New, being especially
evanescent in Tasitia where, however, traces of
the white markings remain distinct. It is sig-
nificant, however, that the black and white apex
is also lost in one of the forms of L. chrysippus,
viz. the variety dorippus (= klugii), abundant in
many parts of Africa and also extending by way
of Aden and the west coast of India as far as
Ceylon. There is, in fact, much resemblance
between the pattern of dorippus and such a form
of Tasitia as berenice, the likeness being especially
apparent in the indications of the former presence
of the white apical bar. In the forms of Tasitia,
as in some of Limnas, the ground-colour becomes
darker and richer—a development especially well
seen in 7. berenice of Florida. Thus the two chief
points in which the pattern of Tasitia differs from
that of typical L. chrysippus, viz. the darker,
richer ground-colour and the evanescent apical
markings, are both presented by abundant Old
World forms of the latter species. The superficial
resemblances between these Old and New World
Danaines are precise and often extend to minute
details. Thus the scent-pouch on the hind wings
of the male, best seen from the under surface, is
similar in Salatura and Anosia, while the resem-
blance between Limmnas and Tasitia in this respect
is even more striking.
The resemblances above described suggested the
investigation and comparison of structural charac-
ters in order still further to test the relationship
158 MIMICRY IN N. AMERICAN BUTTERFLIES
between these Old and New World Danaines, and
also the validity of the genera created by Moore.'
Such a comparison had already been partially made
by Rothschild and Jordan, who in 1903 published
the conclusion that Limnas and Tasitia cannot be
generically separated.* I therefore wrote to my
friend Dr. Jordan, asking if he would kindly
extend his survey over all the four so-called genera.
He found that in Salatura genutia and Anosia
plexippus, having larvae with two pairs of fila-
ments,’ the male genitalia are of the same type ;
while in Limnas chrysippus and Tasitia berenice,
having larvae with three pairs of filaments, these
genitalia are of a second type. The final opinion
of this distinguished authority on the relationships
between the Rhopalocera, was given in the fol-
lowing words ‘ :—
‘It appears to be certain that Anosia plexippus does not
stand apart from the others. Therefore, if Tasitia berenice,
Limnas chrysippus and Salatura genutia are placed in one
1 Proc. Zool. Soc. Lond., 1883, 201.
2 Nov. Zool. vol. x, Dec., 1903, 502.
* Dr. Jordan was at first inclined to think that Anosia plexippus
should be separated generically, basing his conclusion in part on
the larval characters (Trans. Ent. Soc. Lond., 1908, 450). A more
extended review of the Tring material pointed in the opposite
direction, and Dr. Jordan wrote on December 10, 1908, as follows:—
‘I find from our specimens Ge preserved larvae] that—
(1) in Euploea (in the wide sense) there are 4 pairs of filaments,
or three (the 3rd being absent), or two (the 3rd and 4th being
absent).
2) In Danaidaze, incl. of Anosia & Limnas, there are 3 pairs (the
3rd of the 4 pairs of Euploea being absent), or 2 pairs (the 2nd
and 8rd being absent). I find that, for instance, genutia and
purpurata have 2 pairs only, like plexippus. The larva therefore
does not furnish any argument for separating plexippus as a
enus.’
(a In a letter to the author, dated December 15, 1908,
-
|
ALL DANAIDAS CLOSELY RELATED 159
genus,’ plexippus also must be included. I do not think you
need hesitate thus to simplify the classification of these
insects.’
I have no hesitation in accepting this advice,
and in fusing all the four genera created by
Moore into the single genus Danaida. Within
this genus it has been made evident that the
group of forms ranged around Danaida plexippus
is the New World representative and close ally
of the group of D. genutia; while that of D.
berenice is similarly representative of the group of
D. chrysippus. It is interesting to note that both
the American Danaidas have become much larger
than the corresponding Old World species, and
that the most northern forms are larger than the
southern in both hemispheres—the probable
result of a slower metamorphosis in a more
temperate climate.
EVIDENCE THAT DANAIDA IS AN OLD WORLD
GENUS THAT HAS INVADED THE NEW
The suggestion might perhaps be made that
the New World forms of Danaida are the more
ancestral, and that those of the Old World have
been derived from them by migration westward.
There is no reason for concluding that the
Danaidas of either geographical area possess a
more primitive structure than those of the other ;
we are therefore driven to consult other lines of
? Dr. Jordan's opinion that these three genera should be united
is quoted in Trans. Ent. Soc. Lond., 1908, 450.
160 MIMICRY IN N. AMERICAN BUTTERFLIES
evidence. The following comparisons clearly indi-
cate that Danaida is an Old World genus which has
invaded America at no very remote period : (1)
the far larger number of the Old World forms
and the greater degree of specialization by which
some of them are distinguished ; (2) the place of
Danaida as one out of a number of nearly related
genera making up the Danaini, a large and
dominant Old World group, per contra its isolated
position in the New World; (3) The highly
developed and complex mimetic relationships of
the Old World Danaidas.
This last statement requires some expansion
and exemplification. Allusion has already been
made to the resemblances which have grown up
between different species of Danaida in the same
island,—resemblances in which the forms of
chrysippus appear to act as models. Even more
striking is the mimetic approach of certain Old
World Danaidas to species of the other dominant
Oriental section of the Danainae—the Euploeini.
Thus in the Solomons, Danaida (Salatura) insolata
is a beautiful mimic of the dark white-margined
Euploea brenchleyi, while in the same islands,
Danaida (Salatura) decipiens mimics the dark,
white-spotted Euploea asyllus.! Finally, and most
convincing as evidence of long residence, are the
numbers of mimics which in the Old World have
taken on the superficial appearance of species of
1 See J. C. Moulton in Trans, Ent. Soc. Lond., 1908, 603, 604:
Pl, XXXIV, figs. 5, 10.
.
:
J
MIMICRY OF OLD WORLD DANAIDAS 161
Danaida. In addition to the extraordinary degree
to which the Mimicry of D. chrysippus is carried
in Africa, it is mimicked in the Oriental Region
by the females of Hypolimnas misippus and of
Argynnis niphe, and by the males of certain species
of Cethosia. Danaida genutia and the forms related
to it are also mimicked by male Cethosias and
extensively by the females of species of Elymniinae,
while incipient Mimicry is seen in the males of
some of them. With the exception of Hypolimnas
misippus, common to both Regions, the Oriental
mimics of Danaida do not approach the degree of
resemblance attained by the best African mimics
of D. chrysippus. _It has already been pointed out
that the Oriental mimics of this genus are far
less numerous than the African. On the other
hand, it is a curious fact that the only North
American mimic of D. plexippus,—Limenitis
(Basilarchia) archippus—reaches a far higher
degree of resemblance than that attained by
any of the characteristically Oriental mimics of
Danaida.
The evidence as a whole enables us to decide
that Danaida is an Old World genus and a com-
paratively recent intruder into America, while
the perfection of the likeness attained by an
indigenous American mimic proves that, under
favourable circumstances, such resemblances may
be rapidly produced. I do not, of course, mean
to imply that the transformation was in any way
sudden, or by other than minute transitional
M
162 MIMICRY IN N. AMERICAN BUTTERFLIES
steps. The evidence for this conclusion will be
clearer when some of these steps have been
described in detail (see pp. 164-8).
THE LINE OF MIGRATION BY WHICH DANAIDA
ORIGINALLY ENTERED AMERICA
There can be little doubt that D. plexippus
invaded America by way of the north, probably
following the line of the Aleutian Islands, In
North America it possesses an astonishing distri-
bution for a member of so tropical a group,
ranging immensely further north than any other
Danaine in the world. Furthermore, D. genutia,
the probable representative of its Old World
ancestor, extends far beyond the tropics into
Western and Central China. A study of the
distribution of the Asclepiad food-plants on the
eastern coast of Asia might perhaps throw light
on the problem. JD. plexippus was certainly the
earlier of the two invaders of the New World.
This is clearly shown by the extent of its own
modification no less than by the changes it has
itself produced. Its immense size, the shape of
the hind-wing cell, and the form of the fore wings
indicate that it is far more widely separated
than is D. berenice from the nearest Old World
species. It has furthermore been resident in North
America long enough to effect profound changes
in the pattern of an indigenous Nymphaline
butterfly, rendering it an admirable mimic;
whereas D. berenice, and probably its form strigosa
== - ~~”
INVASION FROM THE NORTH 168
also, have only effected comparatively slight
modifications in the mimetic pattern already
produced under the influence of plexippus (see
pp. 168-72), It is impossible to feel equal
confidence in suggesting the line by which the
later invasion of the more tropical D. berenice
took place ; but it is on the whole probable that
it too came by way of the north during some
temporary period of warmth. It is tolerably
certain that it did not invade North America
from the south. For although D. berenice and
strigosa have produced—as is shown above—far
less change in the indigenous N. American
fauna than plexippus, they have still caused
distinct and perfectly effective modifications in a
single species; whereas in South America their
representatives have not been shown to have had
any effect at all. It is probable that both the
American Danaidas as they pressed southward
were ‘held up’ for a considerable time at the
northern borders of the Neotropical Region,
unable at first to penetrate that crowded area.
Finally they burst their way through and are now
abundant throughout all the warmer parts of the
Region, the forms of plexippus extending further
into the temperate south, just as in the Northern
Hemisphere they range further north than those
of berenice. We are made to realize the recent
date of the invasion of South America when we
remember that nowhere else in the world do
Danaine butterflies of equal abundance ‘range
M2
164 MIMICRY IN N. AMERICAN BUTTERFLIES
through a crowded area without producing any
effect on any member of the Lepidopterous
fauna, or without themselves being affected
thereby.’' Abundant wide-ranging Danaines
in the Old World, even when much smaller
and with a less marked appearance, invariably
produce some effect, and often themselves
exhibit Miillerian resemblances.
THE EVOLUTION OF LIMENITIS (BASILARCHIA)
ARCHIPPUS AS A MIMIC OF THE INVADING
DANAIDA PLEXIPPUS
It has already been mentioned that a single
species, undergoing corresponding modifications,
provides a mimic for each of the three Danaine
models (including strigosa). We will first con-
sider the well-known beautiful mimic of D. plez-
ippus; for it undoubtedly arose earlier than the
others.
The abundant Limenitis or Basilarchia archippus
is closely related to the Palaearctic species of
Limenitis, a group which includes the well-known
British ‘White Admiral’ (Z. sybilla). ‘The ex-
ample is unusually instructive, because the non-
mimetic ancestor of the mimic is still very
abundant in Canada and the north-eastern States,
and we thus possess the material for reconstruct-
ing the history by which the one form originated
from the other. We know that this ancestor,
Limenitis arthemis, has persisted almost unchanged,
1 Trans. Ent. Soc. Lond. (1908), 452.
NON-MIMETIC PARENT OF MIMIC 165
because of the resemblance between its pattern
and that of other species of Jimenitis (using the
name in the broad sense) from all parts of the
circumpolar land-belt, including North America
itself. The difference between the pattern of
the mimic and that of its non-mimetic parent
is enormous—probably as great as that between
any two butterflies in the world; but the steps
by which the transition was effected were long
ago suggested by S. H. Scudder,' and have
recently been worked out in considerable detail
by the present writer.’
L. arthemis exhibits the characteristic ‘ White
Admiral’ pattern— possessing on the upper sur-
face a dark ground-colour with a broad white
band crossing both wings, and white markings
within the apex of the fore wing. Reddish or
orange spots between the white bands and the
margin are found in the hind wings of many
individuals, more rarely in the fore wings. These
latter markings are of the utmost importance,
for, as Scudder long ago pointed out (l.c., 714),
they undoubtedly provided the foundation for
the change into the mimetic archippus.
A careful comparison between arthemis and
archippus reveals the most conclusive evidence
of selection. The one species has become changed
into the other precisely as if an artist were to
paint the pattern of archippus upon the wings
1 Butterflies KA the Eastern United States and Canada, Cambridge,
Mass. (1889), 278, 714,
? Trans. Ent. Soc. Lond. (1908), 454-60.
166 MIMICRY IN N. AMERICAN BUTTERFLIES
of arthemis, retaining unchanged every minute
part of the old markings that could be worked
into the new, and obliterating all the rest. Thus,
extending in this direction and wiping out in
that, the great transformation has been effected
and one of the most beautiful mimics in the
world produced.
The evolution of the mimetic pattern on the
under surface has involved an even more elabo-
rate change than on the upper; but it is not
necessary to repeat here the details which have
been only recently fully described.' I will, how-
ever, allude to the fate of the most conspicuous
feature of arthemis, the broad white band crossing
both wings. Save for the traces mentioned below,
this marking has disappeared from both surfaces
of the hind wing of archippus, but its black outer
border is retained, and, cutting across the radi-
ate pattern formed by the strongly blackened
veins, detracts considerably from the mimetic
resemblance.2- On the under surface distinct
1 Trans. Ent. Soc. Lond. (1908), 454-60.
2 In the course of the address on December 31, 1908, I remarked
that if we could revisit the earth in a few hundred years we might
expect to find that this black line had disappeared from the hind
wing, and the mimetic resemblance correspondingly heightened.
Atthe conclusion, Mr. John H. Cook of Albany, N.Y., informed
me that he had discovered near his home many individuals in
which the black line was wanting from the upper surface. A few
days later he very kindly sent me a record of his observations, of
which an abstract is printed as a note at the end of this address
(see pp. 211-12). The study of Mr. Cook's facts shows that near the
city of Albany not only did the stripeless variety occur commonly _
(1 in 14), during the three seasons in which the observations were
conducted, but also transitional forms with more or less broken
stripes were far commoner than the normal archippus (18 to1). The
ANCESTRAL TRACES IN THE MIMIC 167
traces of the white band may commonly be seen
along the inner edge of the persistent black
border. So far as my experience goes these
traces are only to be found on the upper surface
in the form hulsti (Edw.). The modification of
the same marking in the fore wing is more in-
teresting. Here towards the costal margin the
black outer border is much expanded, invading
the white band and cutting off from two to four
white spots from its outer part. While the rest
of the band disappears except on the costa itself,
these black-surrounded white spots now repre-
sent the sub-apical pale-spotted black bar of the
model. The new marking is larger and more
conspicuous on the under surface, corresponding
with the strong development of white on this
surface of the model. The costal margin of the
fore wing of the latter is streaked with long
narrow white markings. In correspondence with
this we find, commonly on the under surface,
more rarely on the upper, that the extreme
fact that entirely stripeless individuals were invariably males is
contrary to the rule that mimetic resemblance tends to develop
more rapidly and fully in the other sex. But in this species I have
observed another point in which the female tends to be more
ancestral than the male, viz. the more frequent and complete
development of the white spot in the cell of the fore-wing upper
surface (a common feature of Limenitis, although now generally
absent from L. arthemis). :
Mr. Cook’s observations show that a single marking—and one
so simple that we might have expected it to act as a ‘unit
character ', so small a fraction of the pattern that we could hardly
speak of its sudden disappearance as ‘discontinuous’ evolution
—that even this behaves differently on the two surfaces of the
wing, while the individuals from which it has disappeared are
immensely outnumbered by those in which it is transitional.
168 MIMICRY IN N. AMERICAN BUTTERFLIES
costal end of the white band is retained, often
for the full breadth of the marking, forming
a linear streak.
I have dwelt upon the changes undergone by
the white band as an example of the way in which
the new markings have been carved out of the
old. The changes in the elaborate marginal
pattern would have been equally convincing as
evidence for a gradual and ‘continuous’ trans-
formation.
THE MODIFICATION OF THE LIMENITIS MIMIC
OF DANAIDA PLEXIPPUS INTO A MIMIC OF
D. BERENICE IN FLORIDA .
Danaida plexippus occurs together with D. bere-
nice in Florida, but the latter far outnumbers the
former, and the modification of Limenitis archippus
into the form floridensis, Strecker (= eros, Edw.)
is probably entirely due to the predominance of
one model over the other. Data for determining
the exact proportions in various localities would
be of high interest. There is no reason for
believing that berenice is in any way more or less
distasteful than plexippus, but its abundance makes
it a more conspicuous feature in the environment.
It is evident that the change has been of the
kind expressed in the above heading; for, as has
been already implied on pp. 162-8, traces of the
former Mimicry of plexippus persist in floridensis
and tend to detract from the resemblance more
en i
a “44
cA)
:.
a ;
NEW MIMIC EVOLVED FROM OLD 169
recently developed. This is especially the case
with the conspicuously blackened veins of archip-
pus, which are so important a feature in the like-
ness to plexippus. These, although obscured by
the general darkening, are still recognizable in
Jloridensis, diminishing its resemblance to berenice
on the upper surface of both wings and on the
under surface of the fore wing. Inasmuch as
the details have been recently published else-
where,' I will only dwell on one further point in
the resemblance of floridensis to berenice—and
that because the extensive observation of large
numbers of specimens is greatly needed. I spoke
on pp. 166-7 of the persistent traces of the white
band on the hind-wing under surface in many
individuals of LZ. archippus. These are ancestral
features, diminishing the mimetic resemblance
to D. plexippus. But in D. berenice there are
conspicuous white spots towards the centre of
the hind-wing under surface, and these, at any
rate upon the wing, would bear some resemblance
to the ancestral spots of the Limenitis mimic.
Now in my very limited experience of floridensis
these spots were sometimes exceptionally deve-
loped and, outlined with black on their inner
edges, were certainly far more distinct and con-
spicuous than in ZL. archippus. The appearances
I witnessed suggested the possibility of the
recall of a vanishing feature in consequence of
= : a Ent. Soc. Lond. (1908), 460, 461. See also Scudder,
C.,
170 MIMICRY IN N. AMERICAN BUTTERFLIES
selection based on a likeness to certain white
spots present in the new model (berenice) but
absent from the old (plexippus) But many
hundreds of specimens from different localities
scattered over the total area of distribution re-
quire to be examined from this point of view.
An even more interesting inquiry would be to
trace the range of the floridensis form northward
and determine the relationship of its limits to
the zone in which berenice becomes scarce and
disappears, and above all to ascertain whether
floridensis on the borders of its range interbreeds
with archippus and how far transitional varieties
occur. Interbreeding between the two forms,
if possible, would be of extraordinary interest.
It is also of importance to ascertain precisely
how far the one form penetrates the area of the
other. Scudder indeed states that floridensis
ranges into the Mississippi Valley and Dakota,
far beyond the limits of Danaida berenice. It
would be deeply interesting to make an exact
comparison between such specimens and those
from Florida, and also to ascertain the proportion
which they bear to typical archippus. By far
the most important feature in the evolution of
floridensis is the general darkening of the ground-
colour, and the material for such a transformation
certainly exists freely in archippus, for the shade
of brown varies immensely and may often be
seen of as dark a tint as in floridensis, but not
in my experience of precisely the same shade.
|
|
|
-
.
INVESTIGATIONS REQUIRED 171
The proportion of such dark forms in various
parts of the immense range of archippus would
be another interesting inquiry.
THE MODIFICATION OF THE LIMENITIS MIMIC
OF DANAIDA PLEXIPPUS INTO A MIMIC OF
THE STRIGOSA FORM OF D. BERENICE IN
ARIZONA
The differences between L. archippus and the
form hulsti (Edw.) are more striking than those
which distinguish floridensis from the former.
The upper surface of the hind wing of hulsti
retains or more probably has recalled distinct
traces of the white band, although the black
stripe is evanescent. It is probable that, upon
the wing, these vestigial white markings produce
a general likeness to the pale-streaked hind-wing
upper surface of strigosa. Other points in which
hulsti differs from archippus and approaches stri-
gosa are the reduction of black and the general
appearance of the white spots in the subapical
region of the fore wing, and the dull tint of the
ground-colour. I have had hardly any experi-
ence of this interesting form and owe the above
details to Dr. W. J. Holland’s figure and descrip-
tion. It is obvious that all the investigations
suggested in the case of floridensis are, mutatis
mutandis, equally available and equally important
in the form hulsti.
1 Butterfly Book, 84, 185, Pl. vii. f.5. Dr. Holland fully recog-
ned the mimetic significance of the pattern and colouring of
ulsti,
172 MIMICRY IN N. AMERICAN BUTTERFLIES
The geographical distribution of hulsti strongly
supports the conclusion that it was derived from
archippus and not immediately from an arthemis-like
ancestor. I have not yet had the opportunity of
ascertaining whether this hypothesis is supported
by evidence derived from a careful study of the
pattern.
It is deeply interesting to observe that the same
LTimenitis arthemis-like species, from which archip-
pus, floridensis and hulsti—mimies respectively
of the three Danaidas, plexippus, berenice and
strigosa—have been directly or indirectly evolved,
has also given rise to L. astyanax (ursula), the mimic
of a Papilionine model. Evidence in favour of the
comparatively recent origin of these mimicking
forms is to be found in the well-supported facts
which indicate that astyanaz still interbreeds with
arthemis along their geographical overlap, and
that it may even occasionally pair with the sister
species archippus.!
The earlier stages of archippus and astyanax are,
according to Scudder (l.c., 254, 255), with difficulty
distinguished from those of arthemis, but astyanax
presents the closer likeness of the two; a fact
which, together with those referred to-in the last
paragraph, points to the conclusion that it arose
even more recently than archippus.
The further consideration of astyanax is best
deferred until some account has been given of the
1 Scudder, 1. c., 283,289. Trans. Ent. Soc. Lond. (1908), 473, 474.
RECENT ORIGIN OF MIMICS 178
Papilionine models, and until certain general
conclusions have been discussed in the following
section.
BEARING UPON THEORIES OF MIMICRY OF
THE TRANSFORMATION WROUGHT BY THE
INVADING DANAIDAS
It has been shown that the Danaine models
invaded America from the Old World tropics,
probably following a northward route. Their
patterns are but little changed in the new sur-
roundings, and they still keep the characteristic
appearance of Old World Danaidas. Furthermore,
such changes as have taken place in the older
invader, D. plexippus, during its residence in the
New World, are also retained in those colonies
which, during the past half-century, have been
re-establishing themselves in the Old World.
These facts support Darwin’s conclusion that the
physico-chemical influences of soil, climate, &c.,
are of comparatively slight importance, a conclu-
sion which made him feel ‘inclined to swear at
the North Pole, and . . . to speak disrespectfully
of the Equator ’.!
The mimics on the other hand are derived from
characteristic and ancient inhabitants of the
northern land-belt. If, as the followers of the
theory of External Causes (see p, 148) maintain,
species are the expression of the physical and
'TIn a letter to Sir Charles Lyell, Oct. 11, 1859.—Life and
Letters, ii. 212.
174 MIMICRY IN N. AMERICAN BUTTERFLIES
chemical forces of the environment, then the
Danaidas express the Old World tropics and the
species of Limenitis the northern land-belt. We
might expect on this theory that the Danaidas,
when they invaded the northern zone, might come
to resemble the Limenitis ; but the transformation
that has actually occurred is entirely inconsistent
with any such hypothesis. Although the Danaidas
have undergone no important change in the new
environment, their presence has entirely trans-
formed and brought into a close superficial re-
semblance to themselves the descendants of a
member of an ancient group. Such a fact is in-
consistent with any interpretation as yet offered
except that which refers the change to the accu-
mulation by selection of variations which promote
a likeness to the Danaidas.
The facts also bear upon the two theories of
Mimicry associated with the names of H. W. Bates
and Fritz Miller. According to Bates’s theory,
Mimicry is a special form of protective or cryptic
resemblance. In the ordinary examples of this
principle, species are aided in the struggle by
concealment, by a likeness to some object of no
interest to their enemies (such as bark, earth, &c.);
in these special examples (called mimetic) species
are aided by resembling some object which is un-
pleasant or even dangerous to their foes. Fritz
Miiller’s theory of Mimicry includes the cases
in which the mimics, as well as their models,
are specially defended, although generally to an
DOMINANT FORMS BECOME MIMICS 175
unequal degree.' The resemblance is due to the
advantages of a common advertisement. Before
the growth of a mimetic likeness, Batesian mimics,
it is reasonable to assume, belonged to the immense
group of species possessing a cryptic appearance ;
Miillerian mimics on the other hand may be
assumed to have possessed warning or aposematic
colours of their own previous to the adoption of
those of another species. This test is more readily
applied than might be supposed ; for a comparison
with allied non-mimetic species, and with the
non-mimetic males of mimetic females, will gene-
rally indicate whether the ancestral pattern of
a species now mimetic belonged to the group of
concealing colours or to that of warning.
The Danaidas invaded North America and
entered an assemblage of butterflies of which the
dominant species are ancient inhabitants of the
northern land-belt. Among them are several, such
as the species of Grapta or Polygonia (the ‘Comma’
butterflies), with beautifully cryptic patterns on
the parts of the wing surface exposed in the rest-
ing position. Nosuch forms have been influenced
by the invaders, but with the whole fauna before
them they have only produced changes in the
dominant group Limenitis, known throughout the
northern belt for a conspicuous under surface and
a floating flight ; also believed to be mimicked by
other butterflies, e.g. the females of the Apaturas
‘It is probable that — abundance ma determine the
relationship of model and mimic in cases where there is no reason
for suspecting any difference in the degree of unpalatability.
176 MIMICRY IN N. AMERICAN BUTTERFLIES
(‘ Purple Emperors’) and the later brood of Arasch-
nia levana.. Furthermore, the close allies of Li-
menitis in South America, the abundant Adelphas,
are beautifully mimicked, not only by females of
the genus Chlorippe, which represents Apatura, but
also by Evycinidae. In another point the facts are
at variance with Bates’s interpretation but har-
monize with Miiller’s. Bates supposed Mimiery to
be an adaptation by which a scarce, hard-pressed
form is enabled to hold its own in the struggle
for existence. But L. arthemis, which represents
with little or no change the species from which
the mimics were derived, persists as a very abun-
dant and flourishing species, while its. mimetic
descendant archippus has gained an immensely
extended range and become almost universally
commoner than any other species of its group
(Scudder, l.c., 266). IL. archippus extends from
Hudson’s Bay to the Gulf of Mexico; over this vast
area it is only rare in the west, and only unknown
in Colorado, Arizona, and New Mexico (l.c., 278).
It is to be observed that the range of archippus
includes the whole of the area (Canada ‘and the
north-eastern States) occupied by the ancestral
form arthemis.
The facts indicate that the changes produced
by the invaders were wrought in the conspicuous
pattern of a dominant indigenous species, and
that the transformed butterfly having adopted the
’ See also the mimetic resemblance to L. astyanax described on
pp. 189-91.
FACTS SUPPORT MULLER’S THEORY 177
advertisement of the still more unpalatable Danaida,
became even more dominant and. gained a far
wider range than before. The mimetic resem-
blance arose in a species which we have reason to
believe possessed warning colours and some form
of special protection before the change occurred.
There is no evidence that the special. protection
was diminished after the assumption of Mimicry,
and, if it remain, the new appearance is still
a warning character, only one that is learnt by
enemies more readily than the old because of the
wide advertisement given to it by Danaida plex-
ippus. The facts harmonize with the theory of
’ Fritz Miller rather than with that of H. W. Bates.
THE ‘POISON-EATING’ SWALLOW-TAIL BUTTER-
FLIES (PHARMACOPHAGUS) AS MODELS FOR
MIMICRY
The late Erich Haase gave the name of Phar-
macophagus or. ‘ Poison-eater’ to the section of
swallow-tail butterflies whose larvae feed upon
Aristolochia or allied species, and he made the
probable suggestion that the qualities which render
them distasteful are derived from the juices of
the food-plant. The poison-eating swallow-tails
are abundant in tropical America and the Oriental
Region, but with the. exception -of antenor in
Madagascar are wanting from the Ethiopian
Region.. They are extensively mimicked by
swallow-tails.of the other two sections :—Papilio,
of which machaon may be taken as a type, and
N
178 MIMICRY IN N. AMERICAN BUTTERFLIES
Cosmodesmus, of which podalirius serves as an
example. The distinction between these three
sections of Papilionidae extends to larval and
pupal stages, as was originally discovered by
Horsfield. It was made the basis of Haase’s
classification,' recently confirmed and amplified
by Rothschild and Jordan.? The latter authori-
ties propose the names ‘Aristolochia Swallow-
tails’, ‘ Fluted Swallow-tails’, and ‘ Kite Swallow-
tails’, respectively for Haase’s sections Pharma-
cophagus, Papilio, and Cosmodesmus.
The Pharmacophagus swallow-tails are not so
well known as models for Mimicry as are the
Danainae, Acraeinae, &c., and it is therefore ex-
pedient to say a few words about the section
before considering the effect produced by one
of its members in North America.
In tropical America not only are the species of
Pharmacophagus extensively mimicked but Mimicry
is also strongly developed within the limits of the
section itself, viz. between the two dominant
groups Aeneas and Lysander. In these groups
the males are commonly very different in appear-
ance from the females and frequent more open
habitats such as the banks of rivers, &c., the
females being found in the forest. In the internal
Mimicry between Aeneas and Lysander the males
resemble the males, the females the females, but
the female patterns are alone extensively mimicked
; 1 Researches on Mimicry, Pt. ii, Stuttgart, 1896, English trans-
ation.
2 Nov. Zool., xiii (1906), 411-752.
4 “
THE ‘POISON-EATING’ MODELS 179
by other groups—Papilio, Cosmodesmus and certain
Pierinae. I have as yet only come across a single
example (a Cosmodesmus) in which the pattern and
green markings of the males are mimicked. One
or two species (e. g. Ph. hahneli) of Pharmacophagus
are themselves mimics of dominant Ithomiine
genera.
It has already been pointed out on p. 187 that
in the Papilio mimics of Pharmacophagus the re-
semblance is often attained by the females alone,
a tendency exemplified in North America as shown
on pp. 181-4. In Cosmodesmus, on the other hand,
where the Mimicry of these models reaches a far
- higher level of perfection, it is equally pronounced
in both sexes. In Africa, on the other hand,
where, in default of Pharmacophagus models, the
swallow-tails of both groups frequently mimic
Danainae and Acraeinae, the resemblances attained
by Cosmodesmus are far less striking than those of
the other section ; yet the relationship of Mimicry
to sex remains unchanged.
In the Oriental Region the female Mimicry
of Pharmacophagus is still characteristic of Papilio,
also appearing in certain Cosmodesmus mimics of
Danainae. Two remarkable features appear in
this Region : (1) the development within Pharma-
cophagus of the gigantic Ornithopteras which do
not appear to be mimicked at all; (2) the appear-
ance within the section Papilio of groups which
are mimicked as extensively, perhaps even more
extensively, than Pharmacophagus itself. Among
N2
180 MIMICRY IN N. AMERICAN BUTTERFLIES
the mimics of these Papilios are not only species
of other groups in the same section but also,
although in small proportion, Satyrine butterflies
and day-flying moths.
The fact that Pharmacophagus and certain groups
of Papilio should be mimicked pre-eminently by
other Papilionidae is evidence that Mimicry is
most easily attained when there are initial resem-
blances of size, shape, habits, and modes of flight
upon which to build.
PHARMACOPHAGUS (PAPILIO) PHILENOR, L., AS
A MODEL FOR MIMICRY IN NORTH AMERICA
Pharmacophagus is a tropical assemblage, but
a few species have found their way into the
northern belt in both the Old World and the
New. Pharm. polydamas, with an immense range
in South and Central America, also extends into
the northern continent but does not there become
the object of Mimicry. Pharm. philenor, ranging
through Mexico and the United States (except
the central district from Colorado northwards)
but only as a straggler in New England and
southern Canada, is on the other hand an important
model for Mimicry.
There is here no such interesting history of past
migrations to unfold as we were able to trace
in the American Danaidas.. Ph. philenor is a
member of the distinctively New World species
of Pharmacophagus, associated together and. sepa-
rated from the Old World species by structural
PHILENOR AN AMERICAN MODEL 181
characters. Rothschild and Jordan state that
every species can be recognized as American by
the examination of a single joint of one leg, and
they are therefore justified in concluding that all
the New World species were derived from a single
ancestor possessing this character. There is no
sufficient evidence that any of the numerous
patterns are ancestral as compared with the others,
although it is tolerably safe to conclude that the
. presence of hind-wing ‘tails’ is primitive as com-
pared with their absence. Following this indica-
tion, we find that as a general rule the specialized
and modern forms are predominant nearer to the
Equator, the comparatively ancestral tailed forms
occurring in latitudes more remote from it both
north and south.
Ph. philenor is a ‘ tailed’ form, although its sub-
species orswa in the Tres Marias Islands is nearly
tailless. It is probably an intruder into North
America from the tropics of the same Continent.
It is well known to possess the characteristics
of distasteful species—gregarious larvae, tenacity
of life, and a strong, disagreeable scent.
THE THREE PAPILIO MIMICS OF PH. PHILENOR
IN NORTH AMERICA
The three swallow-tail mimics of philenor belong
to separate groups of Haase’s section Papilio. All
of them range from the Atlantic to the Mississippi
basin.
182 MIMICRY IN N. AMERICAN BUTTERFLIES
The female of Papilio polyxenes asterius (Cr.)
belonging to the Macnaon Group mimics philenor
on both surfaces, the male on the under surface
alone, except at Guerrero, Mexico, where a form
(ampliata) mimetic on the upper surface is tran-
sitional into the ordinary male.
Papilio glaucus glaucus (L.) belongs to the
Giaucus Group, next but one to the group con-
taining asterius. The female is dimorphic, one form
resembling the male and the other (the twrnus}
form, mimetic of philenor) becoming commoner in
the southern part of the range. In the closely
allied sub-species P. glaucus canadensis (Rothsch.
and Jord.) the mimetic female form is unknown.
Papilio troilus troilus (L.) belongs to the next
succeeding Troitus Grovp, allied to the tropical
and highly mimetic Ancuistapes Group, with
gregarious larvae. Both male and female of
troilus mimic philenor on both wing surfaces.
The most remarkable fact about these three
mimics is not their moderate resemblance to the
primary model philenor, but their extraordinary
likeness to one another. Upon the wing or at
rest at a little distance they would be indistin-
guishable, and even in the cabinet they may be
easily confused. It is to be expected that the
species of allied groups, with patterns converging
towards that of a single model, and approaching
it by variations which tend to be produced in the
1 The species is commonly called P. turnus and its mimetic
female the glaucus form. I follow Rothschild and Jordan in trans-
posing these names.
"
=
|
MIMICRY BETWEEN MIMICS 183
section to which they belong, should incidentally
approach one another. But the strong likeness
between the mimetic forms of troilus, asterius, and
glaucus seems to require something more than this,
and supports the conclusion that there is secondary
Mimicry between the mimics themselves. It is
not necessary to repeat here the details of these
secondary resemblances,' and as a matter of fact
the likeness itself is stronger than might be
inferred from a consideration of the details them-
selves. It is necessary to see it in order to
appreciate it.
It is probable that troilus, mimetic in both
sexes, is the oldest mimic; asterius, non-mimetic
on the upper surface of the male or with very
rough incipient Mimicry, the next to appear ; and
glaucus, mimetic in only one form of the female,
the youngest. These conclusions as to relative
age are on the whole supported by the relative
strength of the detailed resemblances to philenor
in the three mimics.
In attempting to trace the past history, here
again we have the great advantage of knowing the
more ancestral patterns from which the three
mimics were derived :—+roilus from a palamedes-
like form ; asterius from the pattern of its male,
which again leads back to the typical pattern
of the Macnaon Group; the turnus female of
glaucus from the male and non-mimetic female
of the same species.
1 See Trans, Ent. Soc. Lond. (1908), 467-71.
184 MIMICRY IN N. AMERICAN BUTTERFLIES
It is highly probable that the earliest steps
in the direction of Mimicry in asterius and glaucus
were favoured by the appearance of partially
melanic varieties of the female, thus effecting
suddenly that essential change which enables a
butterfly with a yellow ground-colour to become
the mimic of one in which it is black. But this
transformation, immensely important as it is,
supplies nothing more than a tinted paper for the
new picture. That the melanic varieties were
partial is clearly shown by the persistence (in
glaucus) in a subdued and inconspicuous form of
certain ancestral features that do not contribute
to the Mimicry, but above all by the retention
of every element in the original pattern that can
be worked up into the new. By the modification
of these elements in form or colour,—often in both
form and colour,—the detailed mimetic pattern
has been wrought upon the darkened surface.
Valuable confirmation of the history suggested
in the last paragraph is to be found in the dark
form melasina (Rothsch. and Jord.) found in both
sexes of P. polyxenes americus (Kollar), extending
from North Peru to Colombia and Venezuela. This
melanic variety probably represents the darkened
form of asterius before the initiation of the detailed
mimicry of philenor. The sub-species americus does
not enter the range of philenor, and those ancestral
elements which have been retained by its melanie
form have not developed into the mimetic likeness
seen in the more northern sub-species asterius.
Se ——— —- —- ee
. 5
.
MIMICRY AND MELANISM 185
It is well known that all four species (including
philenor) fly together. Even in my own limited
experience I have taken three of them in adjacent
streets on the outskirts of Chicago on the same
day (Aug. 10, 1897), and the fourth in the same
locality a little earlier (July 28). But precise
knowledge of their relative proportions in different
parts of their range would be of high interest.
Again, troilus extends to the North-West Territory
of Canada, probably far beyond the area in which
philenor occurs as a straggler; and it would be
very interesting to compare minutely large num-
bers of such specimens with those from districts
where the model is dominant. A similar study
should be made of the Canadian specimens of
asterius, although this species does not extend
so far beyond the northern limits of poison-
eating model.
From another point of view the interbreeding
of the twrnus female of glaucus with a male from
some northern district where twrnus is unknown or
very scarce would be of the highest interest.
We should here be able to test whether the
Mendelian relationship exists between the parent
form and its partially melanic variety further
transformed by selection,—not a mere melanic
‘mutation’. I trust that my friend Prof. C. B.
Davenport may be able to undertake this experi-
ment at the Cold Spring Experimental Station.
I cannot doubt that breeding could be easily
carried through two generations in a large enclosed
186 MIMICRY IN N. AMERICAN BUTTERFLIES
space exposed to the sun and planted with abun-
dant flowers and the food-plant of the species. It
would probably be safe to use Long Island males,
while female pupae or the freshly bred females
themselves could be readily obtained from further
south.
THE EVOLUTION OF LIMENITIS (B.) ASTYANAX
(F.) AS A MIMIC OF PH. PHILENOR AND ITS
PAPILIO MIMICS
Scudder states that L. astyanaxz ‘ranges from
the Atlantic westward to the Mississippi Valley,
and from the Gulf of Mexico northward to about
the 48rd parallel of latitude.’! It thus falls
entirely within the area of philenor. The northern
boundary of astyanax corresponds with. the
southern limit of its parent arthemis, and Scudder
(1. c., 289) considers that they interbreed and that
the intermediate form proserpina, found along the
narrow belt where the two species or sub-species
meet, is the resulting hybrid. Both arthemis and
proserpina have been bred from the eggs of the
latter. There seems little doubt that astyanax is
a very recent development from arthemis in the
southern part of its range,—so recent that the
areas of distribution still remain distinct and
parent and offspring only meet along a narrow
line. It is probable that archippus arose in the
same manner in part of the area of arthemis, but
? A closely allied species or probably a form of the same species
is recorded by Godman and Salvin from Mexico,
EVOLUTION OF L, ASTYANAX 187
that later, after the separation had become com-
plete, it spread northward over the whole range
of its parent.
_ The evolution of astyanax from arthemis was far
simpler than that of archippus. The great
difference in appearance between parent and
offspring is brought about, as regards the upper
surface, by the disappearance of the broad white
band of arthemis together with all but a trace of
the sub-apical white markings of the fore wings.
Over and within the area formerly occupied by
the white band a bluish or greenish iridescence
spreads from the marginal region where it exists
in arthemis. This marginal iridescence—just as
in astyanax—is bluish in some individuals of
arthemis, greenish in others. Reddish sub-
marginal spots, although rarer in the hind wing
of astyanax, are actually commoner in the fore
wing than in arthemis. This curious fact, together
with the evidence that astyanax and archippus
may occasionally interbreed, suggests the pos-
sibility of some connexion between the origins
of the two mimics.
The under surface of astyanax has not only
similarly lost the white markings, but the
chocolate-brown ground-colour of arthemis has
become transformed into a dark iridescent
greenish-brown. Against this background the
reddish spots near the margin and base of the
wings become far more conspicuous than in the
parent form. The material for this transforma-
188 MIMICRY IN N. AMERICAN BUTTERFLIES
tion in tint is still to be seen in the great variation
of the ground-colour in arthemis.
Although, as Scudder rightly maintains (l.c¢.,
287), L. astyanax is a very poor mimic of Pharm.
philenor, it bears considerable resemblance to
the three Papilio mimics, especially troilus. Al-
though the iridescent blue or green of its upper
surface approaches rather more closely than the
Papilios to the brilliant, steely lustre of philenor,
it is still in this respect widely separated from
the primary model and near to the mimics. The
reddish spots of the under surface offer but a
rough likeness to those of any of the above-
named species, but there can be no doubt that
their emphasis is an element in the mimetic
resemblance. ae
A careful examination of large numbers of
astyanaxz from the extreme south of the range
where it passes out of the area of glawcus and
troilus but remains within that of philenor and
asterius, might yield interesting results. An
investigation of the proportion it bears to the
four Papilionidae in various parts of their common
range would also be of deep interest. Of the
highest importance would be the attempt—which
would probably be successful—to breed astyanax
and arthemis and to ascertain whether the
Mendelian proportions appear in the offspring
of the hybrids. The pairing of astyanax and
archippus, although in this case failure is probable,
ought also to be attempted.
— hl OO SC a
_-=
DIANA THE MIMIC OF A MIMIC 189
THE FEMALE OF ARGYNNIS (SEMNOPSYCHE)
DIANA (CR.) A MIMIC OF LIMENITIS ASTYANAX
The comparatively narrow range of this species
is, as Scudder points out, wholly included within
that of astyanax (l.c., 1802). The Mimicry is
confined to the upper surface, where the blue tint
has even less sheen than that of any other member
of the group clustered round the brilliant philenor.
Apart from the blue expanse, which he admits to
be mimetic, Dr. F. A. Dixey considers that the
female of diana belongs to a set of dark female
forms well known in Argynnis, forms which he
believes to be ancestral.! It is probable that ‘the
recent evolution of ZL. astyanax provided this
ancestral form with a model which it could
approach by small and easy steps of variation ’.?
THE BEARING UPON THEORIES OF MIMICRY OF
PHARM. PHILENOR AND ITS MIMICS
Haase, who always shows an imperfect appre-
ciation of the scope of Fritz Miller’s principle,
apparently regarded all the species mentioned in
the preceding section as simple Batesian mimics
of philenor, neglecting the mimetic relationships
between the mimics themselves. This interpre-
tation is unconvincing, and most naturalists will
agree with Scudder in his hesitation to accept
the two Nymphalines, astyanax and diana (female),
as simple mimics of philenor. The Millerian
1 Trans, Ent, Soc. Lond. (1890), 89-129. 2 Ibid, (1908), 475.
190 MIMICRY IN N. AMERICAN BUTTERFLIES —
hypothesis at once explains relationships that are
mere coincidences under that of Bates.
Pharm. philenor, a probable intruder from the
American tropics, produced its effect upon the
three large Papilios—butterflies with a conspicuous
under surface pattern, in large part reproducing
that of the upper surface, butterflies belonging to
a section that provides models for extensive
Mimicry in the Oriental Region. They may be
regarded as Miillerian Mimics of the primary
Pharmacophagus model, exhibiting a_ certain
amount of Secondary Mimicry of one another.
The four above-named Papilionidae, but
especially the three mimics acting as secondary
models, then produced an effect upon L. arthemis—
that same conspicuous, specially defended element
in the North American butterfly fauna which was
influenced in an entirely different direction by
the Danaine invaders. The result of the former
influence is seen in L. astyanax, a secondary
mimic of the three Papilio mimics of philenor.
One of the most interesting elements in this
complex mimetic system is the final appearance
of a tertiary mimic of astyanax, viz. the female of
Argynnis diana. This was recognized by Scudder,
although, not fully appreciating the Miillerian
hypothesis, he was much puzzled by the fact.
The under surface of the female diana is incon-
spicuous, and, considering also the restricted
1 1.¢.,718, 1802: see, however, 266, where Scudder suggests that
astyanax may possibly be specially protected,
i a i a |
a =
_ '_
MIMICRY OF MIMICS 191
range and relative rarity of the species, it is
probable that this member of the assemblage of
species convergent round philenor is a Batesian
mimic. But its resemblance to astyanax supports
the conclusion that this latter and the sister-
species archippus (and its forms) are Miillerian
mimics and the parent arthemis a_ specially
protected species. The resemblance of astyanax
to the three species of the section Papilio, as well
as the secondary resemblances between the three,
similarly supports the conclusion that these mimics
are Millerian.
I have not hitherto called attention to the
paramount need for experimental research and
field observations directed to test for the presence
of distasteful qualities and to estimate their effect
upon enemies of the most varied kinds. It is of
the utmost importance that such investigations
should be undertaken on the largest possible
scale. In the meantime the Millerian Hypothesis
appears to explain a series of remarkable relation-
ships which remain coincidences under any other
hypothesis.
THE RESEMBLANCES BETWEEN LIMENITIS
(ADELPHA) CALIFORNICA (BUTL.) AND LIME-
NITIS (NAJAS) LORQUINI (BOISD.)
The examples of Mimicry which we have
been considering hitherto are, with the exception
of the widespread ZL. archippus, characteristic of
the eastern side of North America. The present
192 MIMICRY IN N. AMERICAN BUTTERFLIES
instance, the last of the examples known in this
portion of the northern land-belt, is found on the
Pacific coast. The resemblances are somewhat
crude but of quite remarkable interest. .
Limenitis californica, because of its pattern and
colouring, is often placed in Adelpha, a large genus
with over seventy species all confined to tropical
America. Adelpha is separated from the closely
allied northern genus Limenitis by the hairiness
of the eyes in front. Cualifornica is by this
character as well as its more northern. range
associated with the heterogeneous assemblage
‘ Limenitis’, which so much requires a thorough
revision. In adopting this view I accept the posi-
tion assigned to the species by Scudder in 1875.1
Closely allied to californica, of Oregon, Cali-
fornia, and Nevada, is JL. bredowi (Hiibn.) of
Arizona, Mexico, and Guatemala. A much
needed investigation is the determination
whether these two forms meet, and interbreed
along the line of contact.
The southern species or sub-species bredowi, is
associated in Mexico and Guatemala with many
true species of Adelpha of which no less than
thirty-one extend into Central America. To
these it, and to a less extent the northern cali-
Jornica, bear much likeness, especially to A.
dyonysa (Hew.), massilia (Feld), lerna (Hew.), and
Jessonia. (Hew.). This likeness is probably a
mimetic resemblance which extends beyond the
1 Bull. Buffalo Soc. N. Sc. (Feb., 1875), 288.
— es
C-~¢ j ‘rr r ,
MIMICRY ON THE PACIFIC COAST 198
range of the models into Arizona, and, with
diminished effect, still further north into the
allied sub-species. Although the details of the
resemblance leave little doubt that this interpre-
tation is correct for the southern bredowi, it is
possible that californica represents an ancestral
form connecting the Adelphas with Limenitis, a
form left isolated and comparatively unchanged
in the north,' while its southern allies have been
modified by the presence of the dominant
Adelphas. At any rate in one feature neither
sub-species appears to be mimetic, viz. in the
yellowish tint of the conspicuous band crossing
- both wings; for in all the Central American
- Adelphas at all resembling them this marking is
pure white or bluish-white. We cannot hope
to determine how far the pattern of californica
is ancestral until the structural relationships
and the early stages of Limenitis in the widest
sense and Adelpha have been most minutely
investigated.
Limenitis lorquini, occurring with L. californica
in Nevada, California, and Oregon, also extends
far north of this species into British Columbia
and Vancouver Island. Among all the North
American species of Limenitis it is the one which
comes nearest to the Old World forms, as Scudder
recognized when he included it with the European
L. populi in the genus Najas, separating all the
other American forms of Limenitis except cali-
? See, however, pp. 198-9.
0
194 MIMICRY IN N. AMERICAN BUTTERFLIES
Sornica and Basilarchia. Even such fleeting charae-
ters as the markings show the Old World
affinities of lorquni in the strong development
of the pale spot in the fore wing cell and the
position and form of the pale band crossing both
wings. It is to be noted furthermore that its
distribution, and especially its extension north-
ward, along the Pacific coast, bring lorguini into
closest proximity to the Old World species.
In certain important respects the upper surface
pattern of L. lorquini is certainly mimetic of
californica :—
The conspicuous fulvous apical area of the fore
wing ; the yellowish tint of the band crossing both
wings; and, although here the interpretation is
less certain, the fulvous marking at the anal angle
of the hind wing.
1. In the first and most important of these
points of superficial resemblance there is, so far
as my experience goes, a much greater average
development of the fulvous patch in specimens
of lorquint which enter the range of californica in
Oregon and California than in those which come
from Canada, entirely beyond the range of the
model.
The close relationship between californica and
lorquint may incline naturalists to look on their
resemblance as due to affinity and not to Mimicry.
‘It is commonly forgotten that mimicry, being
independent of affinity, occurs between forms of
all degrees of relationship, the closest as well as
LORQUINI MIMICS CALIFORNICA 195
the most remote’;' although of course the latter
are easy to interpret, while the former may be
excessively difficult. In this case, however, there
is neither doubt nor difficulty, for not only is
there the geographical coincidence between the
model and the average increase of the marking
in the mimic, but the fulvous apical marking of
lorquini—of a somewhat richer, deeper shade than
the tawny patch of californica—is due to the in-
ward growth of a marginal marking, while that
of the model occupies a clearly defined sub-
marginal and sub-apical position. The resem-
_ blance is, in fact, produced by markings which
are essentially different; yet in some of the
southern examples of lorquini in which the mark-
ings extend inward to the greatest distance the
superficial resemblance is very considerable.
The above-stated conclusion that the chief
mimetic element of lorquini is on the average
subject to considerable strengthening in the
southern part of its range, is founded on an
examination of the few dozen specimens I have
been able to study in English collections, and
especially the Godman-Salvin material in the
British Museum. I now trust that the subject
may be taken up by American naturalists and
many hundreds of specimens compared from
all parts of the north and south range of the
species.
2. In the second point also, the yellowish tint
1 Trans. Ent. Soc. Lond, (1908), 482.
02
196 MIMICRY IN N. AMERICAN BUTTERFLIES
of the principal band, the resemblance is certainly
mimetic and not due to affinity; for lorquini,
ancestral in certain other features, has here lost
the original whiteness of this marking, preserved
not only in the Old World but in Limenitis
arthemis and L. weidermeyert (Edw.) of the New.
An excessively slight deepening of the yellow
tint could be made out in southern individuals
from the area occupied by the model. In order
to detect the difference, a long series of northern
specimens should be placed beside a similar
series from the south and the two compared in
a strong light. But far larger numbers than
I have seen ought to be examined from this point
of view, and, if it were possible to make it, the
comparison of perfectly fresh specimens would
be most desirable. |
3. The fulvous marking at the anal angle of
the hind wing is excessively variable and often
absent from specimens in all parts of the range.
The comparison of a very large amount of mate-
rial is necessary before we can reach any safe
conclusions as to the existence of mimetic re-
semblance in this feature, and the same is true
of the extremely variable under surface of lor-
quint, in which the development of the inner
row of sub-marginal bluish lunules may be mime-
tic of californica. This feature was generally
suppressed in the Vancouver Island specimens
I have seen.
We now come to the consideration of certain
PROBABLE RECIPROCAL MIMICRY 197
differences between L. californica and its southern
form bredowi which promote a likeness to lorquini.
If these are not mere coincidences, we can hardly
escape the conclusion that there is Reciprocal
Mimicry (Diaposematism) between californica and
bredowt.
1. The wings of both sexes of californica are
more rounded than those of the males of bredowi,
in this respect resembling both sexes of lorquini.
The fact that the southern females have rounded
wings may indicate that this character is ances-
tral in both sexes, the males alone having been
modified in Mimicry of Adelpha. But it is a
probable hypothesis that the presence of lorquini
has prevented this mimetic feature from passing
northward into the males of californica. It does
pass far beyond Adelpha in the northernmost
part of the range of bredowi in Arizona.
2. The fulvous marking at the anal angle of
the hind wing which forms so characteristic
a feature of bredowi, is greatly reduced in cali-
fornica, approximating to lorquini, which in this
respect may be advancing to meet its model
(see p. 196).
3. The following points concern the band cross-
ing the fore wing. Owing to the small size of
the last spot in californica and the different direc-
tion of the spot next to it, the junction between
the bands of fore and hind wing forms a step-like
break in californica, whereas in bredowi the bands
tend to be continuous, approximating more closely
198 MIMICRY IN N. AMERICAN BUTTERFLIES
to the single smooth streak crossing both wings
in the Adelphas. In lorquini this step-like break
and want of continuity in direction is even more
pronounced, Again, the fore wing band of lor-
quini—one of its ancestral features—forms, with
the adjacent hind wing spot, a drawn-out zigzag
like a flattened-down W. By a modification in the
position and direction of the spots of californica
as compared with bredowi, it also gains the ap-
pearance of a very flattened W, although a far
less regular one than that of lorquni. The re-
semblance is only superficial; for corresponding
spots do not occupy the upper angle of the W
in the two species. But the attainment of a
likeness by means that are different from those
employed in another species supports the inter-
pretation of the resemblance as mimetic.
Whatever be the true interpretation of the
resemblances above described, it is of the utmost
importance and interest to study the relative
numbers of californica and lorquint at as many
different points as possible in their common
range, to observe how far they fly together and
present the same appearance on the wing and at
rest from a little distance, and to test their relative
palatability on a variety of insect-eating animals
found in the same area.
The following general considerations support
the conclusion that californica is not an ancient
element in the Pacific fauna of North America,
but a comparatively recent intruder from the
CALIFORNICA A RECENT MODEL 199
south—an intruder that has modified the indi-
genous inhabitant lorquint and has been also
reciprocally modified thereby.
Timenitis in the broad sense is part of the
ancient northern butterfly fauna of North America.
It has here split up into several well-marked
species characteristic of the area. It is highly
susceptible to mimetic influence—far more so
than any other North American group—and
contributes the majority of the examples of
Mimicry from this part of the world. L. archippus
has been shown to be the result of a recent
invasion,—its southern and eastern forms to be
still newer products of the changes in archippus
itself. The sensitiveness of the group is shown
by the fact that, in spite of this recent origin,
3 all except astyanax are most beautiful and striking
mimics; and even astyanax is a better mimic
than lorquini. The fact that lorquini, the member
of so sensitive a group, is an undoubted mimic,
> but a very poor mimic, supports the conclusion
t that the association with its model has endured
for but a brief period, a conclusion also supported
by the diminution of the resemblance outside
the range of californica.
If the relationships which I have found to
exist in the available material—in quantity very
insufficient for such minute comparisons—if these
are confirmed by extensive investigations in
America, it will follow that the resemblances
between L. californica and L. lorquini will be one
200 MIMICRY IN N. AMERICAN BUTTERFLIES
of the most interesting and instructive examples
of Mimicry in the world. Its value will lie in
the early stage reached by the resemblance, to-
gether with the diminution of the likeness in
californica to the south and, especially, in lorquini
to the north. There is no reasonable doubt that
lorquint forms a single Syngamic community
along the Pacific coast of North America, and
we should therefore witness, first, the marked
strengthening of characters in an area of selec-
tion; secondly, their transmission with diminished
effect into other areas.
If what I have observed be the phenomena
presented by the growth, at an early stage, of
a mimetic likeness in lorquini, then that growth
is ‘continuous’ and transitional to the last and
finest degree.
It is perhaps appropriate to state in a few lines
how we may imagine that the selection of minute
characteristics such as the presence or the position
of a single spot may be made. We ourselves
may observe that one individual butterfly is a
better mimic than another. We may then
analyse the pattern, as I have attempted to do
in this address, and realize that the improvement
is due to differences in one or more relatively
minute elements. Recognizing the cause of the
change, we are perhaps prone erroneously to
suppose that enemies recognize it also and that
selection has been brought to bear directly and
consciously upon it. Such a view is almost cer-
SELECTION OF MIMETIC LIKENESS 201
tainly wrong. The only probable hypothesis is
that sharpsighted enemies, without analysing the
markings, recognize differences in degrees of
likeness, and that the selective pressure exercised
by them is influenced by the recognition.
A great deal of attention is rightly directed at
the present day to the value of experiment, and
indeed it is impossible to over-estimate its impor-
tance. But while human performance is of the
deepest interest for the solution of mysteries
innumerable, of more profound significance still,
for the comprehension of the method of evolution,
is the vast performance of Nature herself.! Be-
cause of the bright promise it holds for the under-
standing of Nature’s experiments, I have brought
before you the subject of Mimicry in North
American butterflies. |
In the introductory words I spoke of the relation-
ship of my subject to the teachings of Darwin, and
now I am anxious to connect this address by
a closer link to the personality of the illustrious
naturalist. With the kind consent of Mr. Francis
Darwin, I am able to achieve this object by print-
ing, for the first time, a letter, recently discovered
in the archives of the Hope Department at Oxford,
written by Darwin to the Founder in 1837. It is
concerned with the insect material collected on
? See Carl H. Eigenmann in Fifty Years of Darwinism, New
York (1909), 208.
202 MIMICRY IN N. AMERICAN BUTTERFLIES
the Beagle, and is of peculiar interest because so
few of Darwin’s letters of this early date have
been preserved. The letter clearly exhibits the
keen interest which Darwin took in the working
out of his collections, and the free and generous
use he made of his material. A number of Diptera
captured by him in Australia and Tasmania—
evidently gifts to Mr. Hope—exist in the Hope
Department, and are still in excellent condition.
It is probable that species of other groups collected
by him are also present.
Dear Horr
I called yesterday on you and left a tin box with
a few Hobart Town beetles, which I had neglected to put
with the others. Is not there not [sic] a Chrysomela among
them, very like the English species which feeds on the
Broom.—I have spoken to Waterhouse about the Australian
insects ; you can have them when you like.—The collections
in the pill boxes come from Sydney, Hobart town, and
King George’s Sound.—Do you want all orders for your
work? Some are already I believe in the hands of
Mr. Walker, and you know Waterhouse has described some
minute Coleoptera in the papers read to the Entomological
Soe: To these descriptions of course you will refer.—You
will be glad to find that many of the minute Coleoptera
from Sydney are mounted on cards.—Will you send me as
soon as you conveniently can, one of my boxes, as I am in
want of them to transplant some more insects.—Perhaps you
had better return the Carabi, as they came from several
localities I am afraid of some mistake. We must put out
specimens for the Entomolog: Soc: and your Cabinet.
May I state in a note on your authority that a third or
a half of the insects which you already have of mine from
Sydney and Hobart town are undescribed.—It is a striking
fact, if such is the case, for it shows how imperfectly known
INSECTS COLLECTED ON THE VOYAGE 203
the insects are, even in the close neighbourhood of the two
Australian Capitals.
Floreat Entomologia
Yours most truly
Wednesday. Cuas. Darwin.!
The last words of Darwin’s letter are surely
a most fitting conclusion to this Anniversary
address, and I conclude by quoting his humorous
repetition of them probably twenty years later.
‘“ Floreat Entomologia ” !—to which toast at Cambridge
I have drunk many a glass of wine. So again, “ Floreat
Entomologia.” N.B. I have not now been drinking any
glasses full of wine.’ ?
CONCLUSIONS
It will probably be convenient to sum up
rather fully the chief conclusions contained in
the foregoing address.
1. The study of Mimicry possesses special ad-
vantages for an understanding of the history and
causes of evolution.
1 The letter is addressed: ‘The Revd. F. W. Hope, 56, Upper
Seymour Street.’ At the head Mr. Hope had written ‘D’, and the
date ‘1837’. The red-stamped post-mark gives the date ‘Ju. 22,
1837’. Darwin's own address (36, Great Marlborough Street)
does not appear. At the date of the letter the Entomological
Society of London possessed a mite collection of insects, lon
since dispersed. Darwin knew Mr. Hope before the Voyage, an
speaks in letters to W. D. Fox (1829-30) of his splendid collection
and of his generosity with specimens. He also went for an ento-
mological trip in North Wales with Hope (June, 1829), unfortunately
broken short for Darwin by ill health. See Life and Letters, 1.
174, 175, 178, 181. G. R. Waterhouse and Francis Walker,
referred to in the letter, were both on the staff of the British
Museum.
* To Sir John Lubbock (Lord Avebury), some date before 1857.
— Life and Letters, ii. 141.
204 MIMICRY IN N. AMERICAN BUTTERFLIES ~
2. North America is the most suitable area in
the world in which to begin the study of Mimicry.
3. The great American Danaine butterflies,
formerly included in the genera Anosia and
Tasitia, are a foreign element in the New World
fauna. ‘They bear the closest affinity to a large
group of indigenous Old World Danainae, and
should be fused with the nearest of these (Limnas
and Salatura) into a single genus, Danaida.
4, The Old World origin of Danaida is also
proved by the extent and variety of its mimetic
relationships ; while the path of its invasion of
the New World and of South by way of North
America, may be traced by foot-prints, as it were,
of mimetic effect.
5. That Danaida plexippus is the older invader
is equally shown by the depth of the impression
it has made and the amount of change it has itself
undergone in the New World.
6. Danaida berenice and its form strigosa show
comparatively slight changes in the New World,
and, as regards mimetic influence, have but deep-
ened the foot-prints left by plexippus.
7. Limenitis arthemis, the indigenous ancestor
of the mimic of plexippus, persists with little or
no change; and it is possible to show how far the
very different markings of the mimetic daughter-
species, LZ. archippus, have been carved out of
those of the parent.
8. The recent date of this great superficial
transformation is proved by the close resemblances
CHIEF CONCLUSIONS SUMMED UP 205
between the larval and pupal stages of parent and
offspring. L. archippus also probably occasionally
interbreeds with the mimetic L. astyanax--a still
younger descendant of the same parent.
9. L. archippus probably arose on the southern
borders of arthemis, but afterwards ranged north-
wards over the area of the parent species.
10. The southern astyanax, meeting the northern
arthemis along a narrow belt, is probably repeating
the earlier history of archippus.
11. The forms or sub-species of archippus—
floridensis in Florida and hulsti in Arizona—have
arisen from the earlier mimic of D. plexippus as
a result of the predominance in these localities, re-
spectively, of Danaida berenice and its form strigosa.
12. Details of the older Mimicry persist in
floridensis (and perhaps in hulsti), somewhat de-
tracting from the newer resemblance. ~
13. Certain features in the mimetic likeness
newly attained in Florida and Arizona are prob-
ably due to the recall or the re-emphasis of
elements in the pattern of arthemis which had
been greatly reduced in archippus.
14, The factthat the invading Danaidas haveonly
influenced, among the whole indigenous butterfly
fauna, the dominant conspicuous Nymphaline
genus Limenitis, supports a Miillerian as opposed
to a Batesian interpretation of the phenomena.
15. The fact that the ancestral pattern of a
species indigenous in the temperate zone of the
New World should be wholly transformed by
206 MIMICRY IN N. AMERICAN BUTTERFLIES
a recent invader from the Old World tropics—
the invader meanwhile retaining its original
characteristic pattern,—is demonstrative of the
inadequacy of the theory which refers these
likenesses to the influence of soil, climate, &c.
16. The poison-eating ‘ Aristolochia swallow-
tail’ Pharmacophagus (Papilio) philenor belongs
structurally to the American division of this
tropical section, and is probably an intruder into
North America from the south.
17. Just as tropical species of Pharmacophagus
are mimicked, especially by other sections of
swallow-tails, so the invading philenor is mimicked
by three species of the section ‘ Papilio’.
18. Of these three—Papuilio troilus, mimetic in
both sexes, is probably the oldest; P. asterius,
mimetic in female and on under surface of male,
the next; and P. glaucus, mimetic in one out of
the two forms of female (the mimetic form be-
coming more numerous in the south of the range),
the youngest.
19. The ancestors of these mimics persist with
little or no change—in the two last-named species,
the non-mimetic sex or form; in the first-named,
the allied palamedes. By their aid we can recon-
struct the history of the transformation.
20. In asterius and glaucus partially melanic
forms of the female probably supplied a tinted
background on which the new and mimetic picture
was gradually built up by the modification of
elements in the original non-mimetic pattern..
CHIEF CONCLUSIONS SUMMED UP 207
21. The close resemblance between the three
mimicking species cannot be entirely explained
by their convergence upon a single model, but
seems to imply the existence of Secondary Mimi-
cry between them.
22. Limenitis astyanax has arisen as a very
recent modification of arthemis in Mimicry of
philenor, and especially in Secondary Mimicry
of the three Papilio mimics.
23. The female of Argynnis (Semnopsyche) diana
has arisen as a tertiary mimic, on the upper sur-
face, of L. astyanaz. Its under surface, incon-
spicuous when contrasted with that of the male,
suggests that the species is palatable as compared
with the rest of this combination and that its
Mimicry is Batesian.
24. The dark ground and pale markings of the
female diana are probably analogous with those
of other dark female forms in Argynnidae, while
the blue colouring is an additional feature of
purely mimetic significance.
25. The arrangement of the North American
butterflies which converge on Pharm. philenor,
in concentric rings each mimetic of that lying
within it, strongly supports a Miillerian interpre-
tation of all except the species (diana) in the outer-
most layer.
26. Limenitis (Adelpha) eifiuies of the Pacific
coast is probably a Limenitis mimic of the South
American genus Adelpha,to which its southern
sub-species bredowi bears a stronger resemblance.
208 MIMICRY IN N. AMERICAN BUTTERFLIES
27. Limenitis (Najas) lorquini, in some respects
the most ancestral of the North American species
of the group, is in other respects a mimic of
L. californica.
28. Certain features in which lorquini super-
ficially resembles californica are on the average
more strongly developed in the area where the
two species overlap, while they diminish when
lorquini passes northward of this area.
29. The differences between bredowi, ranging
entirely south of lorquini, and californica are such
as to promote a superficial resemblance between
the latter and lorquini, supporting the hypothesis
that the resemblances between them have been
caused by reciprocal approach (Diaposematism).
30. The differences which distinguish bredowi
from californica are such as to promote a resem-
blance to the tropical American genus Adelpha.
They are retained by bredowi in Arizona, north
of the range of any true Adelpha.! |
31. The detailed study of these resemblances
on the Pacific coast of North America: leads to
the conclusion that the Mimicry is in an incipient
stage and that it has been reached and is probably
still advancing by minute increments,—that the
evolution is ‘continuous’ to the last degree.
32. In addition to their bearing upon the
problems of Mimicry, the examples considered
1 In the southernmost part of the range of bredowi, in Guatemala,
the resemblance to Adelpha was very slightly augmented in the
only two specimens from this locality I have had the opportunity
of studying (Trans. Ent. Soc. Lond., 1908, 485).
AN OPPORTUNITY FOR NATURALISTS 209
in the address afford some of the very best
material for testing the operation of Mendel’s
Law under natural conditions.
I wish again to caution my readers that the
above conclusions have been drawn from the
careful study of a limited number of examples.
Although insufficient in quantity, the English
material is as a whole excellent in quality. Thus,
many of the Pacific coast specimens were cap-
tured by Lord Walsingham, Dr. F. D. Godman,
and Mr. H. J. Elwes, and the geographical data
are of course as full and precise as we should
- expect or wish.
I trust that my brother naturalists in America
will make a determined attack on the fascinating
problems offered by the phenomena of Mimicry
in the North American butterfly fauna. In this
favoured part of the world the problems have
been seen to be sharp and clear as compared
with the almost infinite complexity of the tropics.
If my assistance or advice be of any value it
is always at the service of those who desire to
undertake such investigations.
It has been abundantly shown in the course
of the address that immense numbers of speci-
_ mens are required from the most varied localities ;
and it is likely that difficulties may be presented
by the necessary manipulation, labelling, con-
venient arrangement, and permanent preservation
for the study of future as well as living natural-
P
210 MIMICRY IN N. AMERICAN BUTTERFLIES —
ists, of so large a mass of material. I shall,
however, be most pleased to undertake this part
of the investigation as regards all specimens
accompanied by adequate data of space and time.
Such material, preserved in the Hope Depart-
ment, may be readily compared with the ever-
increasing mass of examples illustrating the same
principles in other parts of the world. If the
indications observed in a small series are still
found to hold in a large one, the growth of such
a feature as the orange-brown apex of the fore
wing in Limenitis lorquini would be demonstrated
by a glance at its average condition in specimens
from the different localities as we pass from
north to south. Furthermore, we might reason-
ably hope that a similar series collected after an
interval not greatly prolonged would exhibit
differences in average composition—the actual
measurable evidence of the evolution of a char-
acter in a species in the natural state. Even
though such evidence be left for our successors
to witness, it still remains our duty to provide
them with the standard by which alone they
will be able to detect and measure it. But 1am
hopeful of more than this, and think it by no
means unlikely that a part of the reward may be
reaped by a single generation of workers.
An excellent example of work done in a single
locality is afforded by the data obtained by
Mr. J. H. Cook, and summarized in the following
note.
J. H. COOK’S DISCOVERY AT ALBANY 211
Nore.— The capture of males of L. archippus in which the black
stripe was wanting from the upper surface of the hind wing, and
of transitional forms of both sexes, at Albany, N.Y., by
John H. Cook.
Mr. Cook first met with the stripeless form in June, 1898,
near Hudson, N.Y. A second specimen was captured near
his home in Albany in 1901, and a third in the same field
in the following year. This latter was a beautiful specimen
apparently only just emerged from the pupa. Mr. Cook’s
attention was now thoroughly aroused and he collected
assiduously at Albany during three seasons, always working
on the best ground to the west of the city, and taking over
90 specimens with the stripe wholly or nearly suppressed.
The following conclusions were reached :—(1) All the stripe-
less archippus captured were males ; (2) The females shared
the tendency but never reached the extreme found in the
other sex; (3) Most of the individuals taken showed some
weakening of the stripe, varying from a slight break (most
commonly between veins III and V, and between V, and
VII,, of the system of Comstock and Needham) to complete
suppression on the upper surface. (4) At Albany individuals
with a broken stripe outnumbered those with an entire
stripe in the proportion of about 18 to 1, while stripeless
specimens were taken in the average proportion of 1 to 14.
Mr. Cook also collected data from other localities and
endeavoured to interest corrrespondents in the problem.
Including the Albany material he secured records of about
1600 specimens and was able to reach the conclusion that
in New England and the Middle States broken-striped in-
dividuals are not uncommon though generally outnumbered
by those with a continuous stripe. He did not meet with
any record of a perfectly stripeless form except for his own
observations and the two specimens to which the name
pseudodorippus has been given. Strecker’s type of this form
exists in Dr. W. J. Holland’s collection (Butterfly Book,
New York (1899), 185). These two pseudodorippus were also
taken in the Eastern States (the Catskill Mountains, and in
Massachusetts), but Mr. Cook, who has seen one and received
P2
212 MIMICRY IN N. AMERICAN BUTTERFLIES —
from Dr. Holland an account of the other, believes that the
disappearance of the stripe is here part of a general blurring
of the colour-scheme in which some elements are obliterated
and there is a tendency towards the invasion of one colour-area
by another. The extreme varieties captured by Mr. Cook
himself, did not, on the other hand, differ at all from the
normal archippus except in the absence of the black stripe
from the upper surface of the hind wings. To this stripe-
less variety Mr. Cook and Mr. Watson have given the name
lanthanis. Mr. Cook’s accurate data and most of his speci-
mens were unfortunately destroyed when the college build-
ings at Albany were burnt down on Jan. 6, 1906. It is
much to be hoped that he may be able to continue his most
interesting observations in this favourable locality, and that
naturalists may be stimulated, by these records, now by
Mr. Cook’s kindness made public for the first — to work
in other North American localities.
Vil
LETTERS FROM CHARLES DARWIN
TO ROLAND TRIMEN (1863-1871)
My friend, Mr. Roland Trimen, Hon. M.A.
(Oxon.), F.R.S., was at the Cape when Mr. Francis
Darwin’s great work was in course of preparation.
On this account his fine series of letters has
remained unpublished up to the present date.
Now, with his kind consent and that of Mr. Francis
Darwin, it is a great pleasure to be able to include
in this memorial volume a single complete set
of letters, moderate in number, but in every way
most characteristic of the writer.
Mr. Trimen has very kindly written the fol-
lowing deeply interesting account of his first
meeting with Darwin exactly half a century ago.
As we read the story, the intense antagonisms at
first aroused by the Origin seem again to rise into
life and activity :——
‘It was in the Insect Room of the Zoological Depart-
ment of the British Museum that I had my first glimpse
of the illustrious Darwin. Towards the close of 1859,
after my return from the Cape,I spent much time in the
214 DARWIN’S LETTERS TO R. TRIMEN
Insect Room identifying and comparing the insects col-
lected with those in the National Collection. One day
I was at work in the next compartment to that in which
Adam White sat, and heard someone come in and
a cheery, mellow voice say, “ Good-morning, Mr. White ;
—I’m afraid you won’t speak to me any more!” While
I was conjecturing who the visitor could be, I was elec-
trified by hearing White reply, in the most solemn and
earnest way, “ Ah, Sir! if ye had only stopped with the
Voyage of the Beagle!” There was a real lament in his
voice, pathetic to any one who knew how to this kindly
Scot, in his rigid orthodoxy and limited scientific view,
the epoch-making Origin, then just published, was more
than a stumbling-block—it was a grievous and painful
lapse into error of the most pernicious kind. Mr. Darwin
came almost directly into the compartment where I was
working, and White was most warmly thanked by him
for pointing out the insects he wished to see. Though
I was longing for White to introduce me, I knew
perfectly well that he would not do so; and after Mr.
Darwin’s departure White gave me many warnings
against being lured into acceptance of the dangerous
doctrines so seductively set forth by this most eminent
but mistaken naturalist.
‘A little while afterwards, on the same day, I again
saw Darwin in the Bird Galleries, where it was, I think,
G. R. Gray who was showing him some mounted birds.
A clerical friend with me, also a naturalist, curiously
enough echoed White’s warning by indicating Darwin
as “the most dangerous man in England ”.
‘Years afterwards, when I had reached the honour
of correspondence and personal acquaintance with
Mr. Darwin, I gave him some amusement by my
account of the impressive manner in which, on the
first day of my seeing him, I had been warned by two
5
f
THE PREJUDICES AROUSED IN 1859 215
naturalists, much my seniors, to give him a wide
berth.’ ?
In working out the various subjects referred
to in the letters, I have received the kindest
help from Mr. Trimen and Mr. Francis Darwin.
Although Mr. Trimen did not keep copies of
his own letters, he was able to remember the
details of nearly all the questions touched upon
in the correspondence, while other data were
recovered from Darwin’s works. Without Mr.
Francis Darwin’s help I should have been un-
able to decipher a few obscurely written words,
or to have obtained other information bearing
upon the conditions under which the letters
were written.
The letters are, as I have already implied,
a typical series. They show all the character-
istics of Darwin in his relations with younger
men who helped him in his work. ‘They are,’
as Mr. Trimen truly says, ‘of value as an ad-
ditional illustration of one of the most charming
and attractive sides of Darwin’s character—the
gracious and glad welcome and recognition he
never failed to extend to every one who even
in the slightest degree endeavoured to render
some aid in his researches.’
In addition to the full recognition he accorded
in his published works, we find, in these letters
as in others, that Darwin not only urged his
correspondent to publish on his own account,
? See p. 219.
216 DARWIN’S LETTERS TO R. TRIMEN
but himself arranged the details of publication
and assisted in drawing up one of the memoirs,
It is easy to imagine the delight and encourage-
ment with which his generous words of praise
for every effort would be received, and how in-
fallibly they would become the inspiration to
further effort. And with all this stimulus and
encouragement there is ever present the warmest
sympathy with difficulties of every kind, and
the keenest anxiety not to overburden another
with trouble or expense. We recognize an un-
bounded love of nature and of discovery, and
the keenest appreciation for the same enthusiasm
in another. We feel, again and again, as we
read these letters, the presence of the bright,
courageous spirit that could pierce the dark
shadow of lifelong pain and discomfort, and
preserve undimmed its humour and its breadth
of view. And the brooding shadow is never
accorded the dignity of recognition on its own
account, being only revealed because of the veto
it had the power to impose—work prevented
or long drawn out, interviews with friends cut
short or postponed.
For this reason brief notes of invitation, which
might otherwise be regarded as trivial, all bear
their part in creating the general impression,
and the whole correspondence remains untouched
and unabridged.
Of the nineteen letters printed in this section
of the book, one (No. 18) is from Mrs. Darwin.
SUBJECTS OF EARLIER LETTERS: 1868-4 217
Of the remainder, fourteen are holograph letters
by Charles Darwin, one (No. 7) is signed and
corrected, while three (Nos. 6, 11, 17) are only
signed by him.
The letters are arranged in the order of date.
Darwin, as was his custom, omitted to write the
year, but fortunately this was nearly always
added by Mr. Trimen himself, together with
the date at which the letter was received.
Publications and the names of species, &c.,
although not underlined in the originals, are,
for the sake of convenience, printed in italics.
The first series of letters, seven in number,
deal with botanical subjects,—especially Orchids,
and the inquiries which grew out of the investi-
gations upon them (such as the Peach-perforating
moths). These are referred to in all seven letters;
Oxalis as material for the study of heterostyled
flowers in Nos, 3-7; insect visitors to Asclepiadae,
Apocyneae, and Physianthus in No, 4; the fertili-
zation by birds of Strelitzia in Nos. 6, 7.
It will be observed that Darwin in the very
first letter began to urge his correspondent to
send home the records of observations for publi-
cation. His advice and help were very soon
accepted, and, in the Fertilisation of Orchids,
Darwin acknowledged the assistance he had
received, and referred to Trimen’s papers, in
the publications of the Linnean Society, on Bonatea
speciosa and Disa grandiflora, in each case specify-
1 Second edit., sixth impression (1899), 40, 76-8.
218 DARWIN'S LETTERS TO R. TRIMEN
ing briefly the peculiarities of structure which
the author had noted as governing access to the
nectary, so as almost to compel the removal of
the pollinia by insect visitors of the right kind.
a
Jan, 31st [1863] Down.
BROMLEY.
Kent. S.E.
My DEAR SIR
I thank you most sincerely for your pleasant letter
and M.S. on Orchids. Your sketches seem to me very
good, and wonderful under circumstances of their execu-
tion. I cannot say how much interested I have been
in studying your descriptions. I think I understand
all; but these Orchids (except Hulophia) are so sur-
prisingly different from anything that I have seen that
I could hardly make them out for some time and even
fancied in some cases that you had miscalled upper
sepal and Labellum. But at last I see my way. I am
no more a Botanist than you say you are, and I know
nothing of any orchids except those seen by me,
Therefore I was astonished at the upper sepal being pro-
duced into a nectary; even more astonished at stigma
standing high above the pollinia &¢ &e.—How curious
is pollinium of Disperis !—What beautiful and new
contrivances you show, and how well you have studied
them! Upon the whole I think No. V. & VI. unnamed
(I have sent your drawings to Prof. Harvey to name
for me) have interested me most: everything seems to
occur in a reversed direction compared with our true
Orchis.—-You do not mention any movement of the
pollinia, when attached to an object; and as you are so
acute an observer, I infer that there are no such move-
SOUTH AFRICAN ORCHIDS: 1868 219
ments; and indeed in those you describe such move-
ments would be superfluous. If you have time to wander
about do watch some kinds and see insects do the work.!
Those with long nectaries would be probably hopeless
to watch as probably fertilized by Moths.—But since
my publication I have ascertained that with Orchis,
Diptera are chief workmen.—They certainly do puncture
the walls of nectary, and so get juice. Disperis would
be grand to watch, and discover what attracts insects.—
You draw so well, and have so seized on the subject,
that you ought really to take up 2 or 3 of the most
distinct genera, and watch them, experiment on them
by mutilation of parts, and describe them and send
over an excellent paper to Linnean Soc’ or some other
Soe’.—I have so much other work, that I hardly know
whether I shall ever publish again, —not but what I have
already collected some curious new matter; for the
subject delights me, and I cannot resist observing.
I am very glad to hear that you do not now think me
so dangerous a person!? You will gradually, I can see,
become as depraved, as I am.—I believe, or am inclined
to believe, in one or very few primordial forms, from
community of structure_and early embryonic resem-
blances in each great class.—
With most cordial thanks I remain my dear Sir
Yours sincerely
Cu. DARWIN
P.S. Would it be asking too great a favour to beg you
' Mr. Trimen writes as follows of his attempts to carry out
Darwin’s advice: ‘I had no success with this, though I watched
a variety of orchids as opportunity offered. A good many visitors
of various orders came, but they were evidently not regular
customers (“ unbidden guests,’’ as Kerner says), and I never saw
a pollinium actually removed by any one of them.’
imen found, however, that one or both pollinia had been
removed from 12 out of 78 flowers of Disa grandiflora.— Fertilisation
of Orchids (1877), 78. * See pp. 214-15.
220 #DARWIN’S LETTERS TO R. TRIMEN
to put 2 or 3 flowers of Satyriwm or your No. V. or VI.
in bottle with spirits and water, and send home by any
opportunity. I would then compare your drawings and
add some remarks on your authority, if I ever publish
again.—But I hope, what will be much better, to see
a paper by yourself.
If you come across Bonatea pray study it—it seems
most extraordinary in description.—
Feb, 16th[, 1863.] Down.
BROMLEY.
Kent. S.E.
DEAR SIR
I have thought you would like to see copy enclosed
of letter by Prof. Harvey giving names of your two
orchids, P]. V. and VI, which were unnamed.'— Now that
I hear that in Satyriwm the nectaries belong to the true
Labellum ;* the relation of the parts is to me very
puzzling: discs, pollen-masses and stigmatic surface
seem all on the wrong side.—If you pursue the subject,
I hope you will observe whether there is any relation
1 The copy of W. H. Harvey’s letter (dated Feb. 3, 1863, Trin.Coll.,
Dublin) states concerning the two unnamed forms: ‘Both are of
the large genus Disa, and I feel confidence in calling them
(Pl. V) D. barbata and (Pl. VI) D. cornuta, both common near
Capetown.’ ‘
The copy of Harvey’s letter contains the following account :
‘Nectariferous back sepals are quite frequent among Cape Orchids—
and correspondently depauperated labella. The Labelle is often
a mere little tongue EOS, anata ih a mere thread [sketch]—
and sometimes as in Brownleia, nearly disappears altogether, and
is adnate to the column.’
‘In Satyrium the two spurred affair is a true labellum—the sepals
and petals small and crowded together at the front of flower—the
opposite to Disa.’
a
SOUTH AFRICAN ORCHIDS: 1863 221
(as in English Orchids) between the rapidity of the
setting of the viscid matter and nectar being stored
ready for suction or confined in cellular tissue.——
I was at Kew 2 or 3 days ago and was telling
Dr. Hooker and Mr H. Gower of your work: they
expressed a strong wish to try whether they could not
cultivate some of your wonderful forms ; and tempted
me by saying that if they could flower them, I sh*
have plants to examine.—I said I would mention the
subject to you; but that of course I doubted whether
you had time and inclination to get them dug up.—
They said the roots might be packed in almost dry
peaty soil or charcoal in moss, and sent to “Royal
Gardens[,] Kew, London,” marking what they were, i. e.
terrestrial orchids from the Cape.—They ought to be
dug up, when completely dormant after seeding over.
—It certainly would be a treat to see a blooming
Satyrium, or Disperis and the odd unnamed form!
They said the safest way of all, but more troublesome,
to send them, would be to plant them in pots in a box,
with a [sic] little glazed windows on two sides under
charge of some passenger. The heat starting them
would be the great risk; But it is not at all likely
you could spare time from your own pursuits.!
Pray believe me, my dear Sir
Yours sincerely and obliged
Cu. DARWIN
' Mr. Trimen informs me that a good many orchids were got
together and dispatched, but (probably owing to unsuitable treat-
ment) did not appear to prosper; and by the time a few of them
contrived to flower, Darwin was too much occupied with other
pressing work to be able to examine them.
222 DARWIN’S LETTERS TO R. TRIMEN
3.
May | 28rd [1863.] Down.
BROMLEY.
Kent. S.E.
My DEAR SIR
I have delayed thanking you for your note and
photograph, as I have no photograph by me of myself.
I have never had a proper “carte” taken; but I en-
close a photograph made of me by my son, which I
daresay will do as well.—
Your accounts of the Disa and Herschelia are excellent,
and your drawings first-rate. I felt so sorry that such
excellent work sh’d remain locked up for an indefinite
period in my portfolio, that you have made me break
a solemn vow, and I have drawn up from your
notes (and selected 4 figures for woodcuts) an account
for Linnean Soc.—I have enlarged a little and explained
and introduced a few remarks.—I hope the Soc’ will
publish the paper, and if so I will send you spare copies.
—The title is “On the Fertilisation of Disa grandiflora
by Roland Trimen Esq’ of the Colon. Off. C. Town:
drawn up from notes and drawings sent to C. Darwin
Esq’.”? I hope that you will approve of this, and not
object to anything in the little paper.—I am very sorry
to hear so poor an account of your health and that you
have so little time to spare for the exercise of your
? The month is indistinctly written and looks more like ‘July’
than ‘May’. Mr. Trimen had, however, noted that he received
the letter at the Cape on July 20, so that this latter month can-
not have been intended. Confirmation of the reading as ‘ May ’ is
afforded by the presence of an envelope (two only are preserved)
with the post-mark ‘BROMLEY, KENT. MY 24. 63’. It also
bears post-marks of ‘ LONDON. MY 25° and ‘ DEVONPORT. MY
26°. It is addressed, ‘Roland Trimen, Esq., Colonial Office, Cape
Town, Cape of Good Ho
e.
2 The paper was pablehed in Journ, Proc. Linn, Soc. Bot., vii
(1863), 144.
..
. ed
—————————
"
CAPE ORCHIDS AND OXALIS: 1863 223
admirable powers of observation.—I did not know all
this; otherwise I sh* not have thought of asking for
plants. Think not a moment more on subject.—Indeed
I ought to work on other subjects.— Yet I am going to
ask a favour, if you know any one who dabbles in
Botany, viz., for seed of any Cape Oxalis: several species
present two forms, one with long pistil and short
stamens; the other form with short pistil and longer
stamens. It is of high interest to me to get seed of any
such species.—To return to Orchids, I now believe that
Hymenoptera and Diptera are generally the chief
workers more than Lepidoptera. With respect to the
limits of Rostellum ; it can in most cases be told only
conjecturally : in Disa the 2 discs (and no part of caudicle
of pollinia) and the part which connects the 2 discs
with the medial upward central fold or ridge, and whole
face of column down to the two confluent stigmas, may
all be considered as the rostellum or modified third
stigma.—With sincere thanks and every good wish,
Believe me, my dear Sir
_ Yours sincerely
C. DARWIN
August 27th[, 1863] Downy.
BROMLEY.
Kent. 8.E.
My DEAR SIR
I am very much obliged for your very pleasant
letter. You have hit upon the right case in Ozalis,
and seeds will really be a treasure tome. I have posted
a paper for you on the dimorphism of Zimum which
if you will read, you will see why I am anxious for
Owalis Ihave a more curious case unpublished ; but the
whole class of facts strike me as very surprising. You
224 DARWIN’S LETTERS TO R. TRIMEN
may rely on my statements, for they have been verifyed
[sic]. Linwm perenne agrees with your Oxalis. Iam
also very glad indeed to hear about the Peaches,—the
more so as it is an exotic in S. Africa.—I am going
in a weeks time to Malvern for a month to try and get
a little strength, and when there I will probably draw up
a notice for Gardener’s Chronicle on your peach case.!—
I daily expect proofs of your paper on Disa; a rough
woodcut is made.—You must not waste time in sending
me many specimens of Orchids in spirits, for I declare
I do not know whether I shall ever have time to work
up mass of new matter already collected on Orchids.
It is capital sport to observe and a horrid bore to pub-
lish.—It pleases me to read your admiration on my
beloved Orchids.—I quite agree they are intellectual
beings! By the bye, I believe I have blundered in
Cypripedium *; Asa Gray suggested that small insects
1 Darwin had suggested in relation to fertilization by moths of
Orchids which seemed to secrete no nectar, that the insects 1
might possibly obtain palatable juices by perforating the softer :
tissues of some parts of the flower. Trimen informed him, as f
bearing on this suggestion, of two good-sized Noctuid moths |
(Egybolis vaillantina, Stoll, and Achaea chamaeleon, Guén.), |
abundant in Natal, where both were styled ‘Peach Moth '—
though absolutely different in appearance—because they sucked
peaches (both ripe on the trees and when fallen). Trimen caught
the latter in the act, and found that they had no difficulty in
piercing the peach-skin with their sharp and strong haustellum.
The observation is quoted by Darwin in Fertilisation of Orchids
(1877), 40. F. Darwin later published an account of the similar
behaviour of a much larger moth of the same tribe which was
accounted a nuisance in Northern Australia owing to its apter
and sucking oranges! He showed how the proboscis in this mot
was armed near the tip with cutting and lacerating processes.
—On the Structure of the Proboscis of Ophideres fullonica, an orange-
sucking Moth (Quarterly Journ. of Microscopical Science, N.S., xv.
384). The number (LX) containing the paper appeared in Oct.,
1875, and it is a curious coincidence that the same organ of the
same species was briefly described and well figured almost simul-
taneously by Kiinckel in the Comptes Rendus for Aug. 30, 1875.
2 When Darwin wrote the first edition of Fertilisation of Orchids
(1862), he misunderstood the mechanism of Cypripedium. In the
_ INSECTS AND FLOWERS: 18638 225
enter. by. the toe and crawl out by the lateral windows.
—TI put in a small bee and it did so and came out with
its back smeared with pollen: I caught him and put him
in again, and again he crawled out by the window:
I cut open the flower and found the stigma smeared
with pollen !
Read Bates Travels they will, I am sure, interest you.
—With respect to Physianthus, I do not know whether
fact is known; but I think it would be well worth
investigating. It is certain that the Asclepiadw
require insect aid for fertilisation. The pollen-masses
are wonderfully like those of Orchids. You ought
to read R. Browns admirable paper on Asclepias in
Transact. Linnean Soc. about 15 or 20 years ago. In the
Apocynee, (which are allied to the Asclepiadw) there
is a genus, which catches Diptera by the hundred:
I have a plant but cannot make it flourish, as I have
always wished to investigate the case. It is said that
the Diptera are caught by the wedge-shaped spaces
between filaments of anthers. But I suspect the plant
somehow profits or requires visits of insects. You ought
to try whether Physianthus will seed if insects are
excluded by a net.—I have seen Hymenoptera from
N. America with numbers of pollen-masses of some
Asclepias sticking to their tarsi; * and the pollen-masses
second edition (1877) he gives, on 230, Asa Gray’s view, and his
own observations confirming it. Mr. Francis Darwin has kindly
given me these references.
was here referring to a note of Trimen’s about the
curious manner in which Lepidoptera and many other insects are
caught by a mechanical (not visgid) contrivance in the flowers of
Physianthus albens,—a native of temperate South America. It
seemed a case in which the plant overdid matters, the numerous
visitors being nipped by hard sharp ridges closing on the proboscis
when introduced into the nectaries, and the captives, in a great
many cases, failed to liberate themselves and carry off the
pollinia, eventually dying where they hung
? T have myself often observed the difficulty with which insects,
especially wasps and Fossors, dragged themselves free from the
Q
226 DARWIN’S LETTERS TO R. TRIMEN
are thus dragged over the stigmas.—R. Brown’s paper
has beautiful illustrations—This is a disjointed, dull
letter, but I have been working all day with very little
strength.—
With every good wish and sincere thanks
Pray believe me
My dear Sir
Yours sincerely
Cu DARWIN
Nov. 25 [1863]
Down.
BROMLEY.
KEnT, S.E.
SS ee 7
My DEAR SIR
I have been laid on the shelf for nearly three
months, and am ordered to do nothing for 6 months by |
my doctors. To write this is against rules.—Many ]
thanks for specimens of orchids and for your kind letter. q
I dare not look at Owalis flowers. I regret much that
you cannot get seed, especially of your trimorphic
flowers." Most species of Owalis shed their seed by
a spurt and the capsules are sensitive to,a touch.
Could you employ anyone to dig up the bulbs of the
2 or 3 forms and allow me to pay; i.e. if they are bulb-
bearers.
The last job I began and broke down was a letter
hold of Asclepiad flowers in North America, and how frequently
their tarsi were bristling with pollen-masses, On one occasion
I found a dead humble-bee held fast by the flower.
1 In answer to Darwin's inquiries Trimen informed him that he
had found trimorphic heterostyled species of Oxalis, and sent draw-
ings and dried specimens. rwin referred to this information
and material in The Different Forms of Flowers on Plants of the
same Species (1877), 169. Trimen’s name is accidentally omitted
from the index of this work.
'—_
a 7" : .
a
SOUTH AFRICAN OXALIS: 1863-4 227
to G. Chronicle on your Peach case .'—I must write
no more,—I live in hopes some day to be able to work
a very little more, but it will be long before I can.—
Sincere thanks for your very kind letter.
Yours very sincerely
C. DARWIN
I forwarded letter to Bates. Pray use me as often
as you like,—
6.
Written by Mrs. Darwin, signed by Charles Darwin.
Down.
BROMLEY.
Kent. S.E.
My DEAR Mr TRIMEN May 18. 1864
I received your letter of Mar 14, some time ago
and was fearful that the Ozalis would never arrive, but
yesterday to my joy they came safe and alive and are
now planted. Please give my sincere thanks to
Mr Mac Gibbon and accept them yourself. The plants
will be invaluable. My only fear is that each kind has
been propagated by offsets from a single stock and if so
they will all belong to the same form.
I am sorry for my mistake about the Disa, I have
sent an erratum to Linn. Journ.®
Thanks for the additional facts about Disa, but I am
sure I do not know what I shall ever do with all
my wealth of new facts.
1 See p. 224 n. 1.
* See the preceding letter (5) on p. 226.
* This was an error in Darwin’s description of the position
of the viscid discs of the pollinia in relation to the passages
to the nectary ; but it was partly due to the point of view from
which Mr. r Trimen’ 8 fig. A was taken. The position was of import-
ance in relation to the only passages of access to the nectary
where a proboscis could be pushed.
Q2
228 DARWIN’S LETTERS TO R. TRIMEN
_I am slowly recovering from my 10 months illness,
but I do not know when I shall regain my old modicum
of strength. I was pleased to see a nice little review
evidently by Mr Bates on your Cape butterflies in that
admirable journal The Nat. Hist. Review."
By the way do you see the “ Reader”. No English
newspaper ever before gave half as good resumés of all
branches of science : the literature is likewise well treated.
I do not know who the Editor is so that my puffing
is honest.
Does Strelitzia regine grow in any gardens at the
Cape? I strongly suspect it must be fertilized by some
honey seeking bird; the structure is very curious and
this w4 be worth investigating.2 With cordial thanks
believe me
Yours sincerely
Cu. DARWIN
G
| Written by Mrs. Darwin, signed by Charles Darwin,
who also inserted the words and letters printed in small
capitals. |
Down.
BROMLEY.
| Kent. 8.E.
My DEAR SIR Nov 25, 1864.
~ Your paper arrived quite safe. I have read it with
much interest, for I have long thought the Bonatea one
of the most curious Orchids in the world. Asa Gray
1 Bates’s very appreciative review was of Part I of Trimen's
Rhopalocera Africae Australis, Cape Town, 1862. It appeared
in The Natural History Review for April, 1864.
2 Trimen supplied some evidence that Darwin’s sus icions were
well founded ; for two species of Sun-bird (Cinnyris) frequented
the flowers of Strelitzia. See Cross and Self Fertilisation in’ the
Vegetable Kingdom (1876), 371 n.
Ae
CAPE ORCHIDS, OXALIS, ETC.: 1864 229
has described in an American Habenaria a nearly similar
contrivance with respect to the nectary as yours. I have
sent your paper to Linn. Soc. and I hope it may be
printed, but that of course I cannot say and IT may
be influenced by cost of engraving."
With respect to the Satyriwm I sh* think that the
pollen masses which you sent had been scraped off
the head of some insect BY THE INSECT ITSELF; I do not
refer to the additional pollen-masses which you saw
growing in their cases.
Most of the Owalis which you so kindly sent me
flowerED, but all with 2 exceptions presented one form
alone. From what I know about Primula, I sh* be
astonished at the same bulb ever producing 2 forms.
In the 2 exceptional cases, one bulb in each lot produced
a distinct form ; but I have very little doubt there ought
to be 3 forms. I got some seed from one of the unions
and have some feeble hopes that they may germinate.
If I have strength (for I keep weak) I sh? like to
make out Ozxalis, so if you have any opportunity I should
still be very glad of seed.
Many thanks about Strelitzia.*?, Would it be possible
to get a plant of the kind that seeds, protected from the
sugar-birds, with another plant unprotected near by ?
I am tired, and so will write no more.
With many thanks pray believe me
Yours very sincerely
Cu. DARWIN
? The paper was published in 1865. It is entitled: On the
Structure of Bonatea speciosa, Linn., with reference to its Fertilisation.
—-By Roland Trimen, Memb. Ent. Soc. Lond.—Journ, Linn. Soc.—
Bot., ix (1865), 156. Darwin mentions this paper in his Notes on
the Fertilisation of Orchids in Ann. and Mag. N.H. for September
(1869), 8, 17; as also in Fertilisation of Orchids (1877), 76, 77.
* See p. 228.
230 DARWIN’S LETTERS TO R. TRIMEN
The invitation conveyed in the following letter
(No. 8) exhibits the characteristic features de-
scribed by Mr. Francis Darwin.' .
It was on this visit that Mr. Trimen heard
Darwin speak with such strong feeling on the
subject of Owen and the article in the Edinburgh
(see p. 28 n. 2).
Dec, 24th [1867] Down.
BROMLEY.
Kent. S.E.
My DEAR SIR
If you are not engaged, will you give me the great
pleasure of your company here next Saturday, and stay
the Sunday with us. We dine at 7 oclock.—You would
have to come by Train to Bromley, but I am sorry
to say this place is six miles from the Station.
I am bound to tell you that my health is very un-
certain and I am continually liable to bad days, and even
on my best days I cannot talk long with anyone; but
if you will put up with the best will to see as much
of you as I can, I hope that you will come.—Pray
believe me, My dear Sir
Yours very sincerely
Cu. DARWIN
Of the remaining eleven letters six (Nos. 9-12,
15, 16) deal with subjects treated of in The
Descent of Man and Selection in relation to Sex ;*
1 Life and Letters, i. 139.
* The following references to information received from Roland
Trimen are printed in the index of this work (Ed. 1874, 682): ‘on
the proportion of the sexes in South African butterflies, 250; on
SUBJECTS OF LATER LETTERS: 1867-71 281
a few words of encouragement on Trimen’s great
paper on Mimicry are contained in No. 18; the
geographical distribution of beetles in No. 19.
Of four brief letters, two contain invitations
(Nos. 13, 14), and two are concerned with diffi-
culties caused by ill-health (Nos. 17, 18, the
latter written by Mrs. Darwin).
The first letter (No. 9) of the following series
introduces, and subsequent letters return to the
question of ocelli (ocellated spots or eye-spots)
on the wings of butterflies and moths. It is evi-
dent, from his reference to the male peacock and
inquiries as to ocelli restricted to male butterflies,
that Darwin was inclined to seek an interpreta-
tion based on the hypothesis of Sexual Selection.’
It was not known until long after the date of
these letters that eye-spots together with certain
differences in shape’ are in the vast majority
of cases characteristic of the butterfly broods of
the wet season. The existing interpretation of
them was first suggested by an observation made
by Professor Meldola and the present writer in
1887, when a lizard was seen to exhibit special
interest in an eye-spot on the wing of the English
‘Small Heath’ butterfly (Coenonympha pamphilus).
the attraction of males by the female of Lasiocampa quercus, 252 ;
on Pneumora, 288; on difference of colour in the sexes of beetles,
294; on moths brilliantly coloured beneath, 315; on mimicry in
butterflies, 325 [324]; on Gynanisa Isis, and on the ocellated
— of Lepidoptera, 428; on Cyllo Leda, 429.’ Nearly all the
above subjects are referred to in letters 9-12, 15, 16.
' Compare pp. 104, 105, 113, 125, 127, 128, 133-5, 140-1.
* Figured by Darwin in Descent of Man, &c. (1874), 429. See
also 428 n. 48.
232 DARWIN’S LETTERS TO R. TRIMEN
It examined the mark and more than once at- —
tempted to seize it. This observation has been
repeated with birds and African butterflies by
Mr. Guy Marshall and others, while large numbers
of specimens have been collected with injuries
to the wing at or near an eye-spot. Hence the
conclusion that the usual value of these mark-
ings is to divert attention from the vital parts
and give the insect extra chance of escape. Their
disappearance from the dry season broods is in-
terpreted as due to the paramount necessity for
concealment during that time of special stress.!_
9.
Jan. 2nd [1868] Down.
BROMLEY.
Kent. S.E.
My prearR Mr TRIMEN
What you say about the ocelli [ocellated spots or
eye-spots] is exactly what I want, viz the greatest range
of variation within the limits of the same species,—
greater than in the Meadow Brown, if that be possible.
The range of difference within the same genus is of
secondary interest; nevertheless if you find any good
case of variation, I sh¢ much like to hear how far the
species of the same genus differ in the ocelli: As I know
from your Orchid Drawings how skilful an artist you
are, perhaps it would not give you much more trouble
to sketch any variable ocelli than to describe them.—
Iam very much obliged to you for so kindly assisting
? Fora further account of this and other uses of these markings,
together with references to the original memoirs, see peepee
in index of Essays on Evolution (1908), 424.
EYE-SPOTS ON BUTTERFLIES’ WINGS: 1868 238
me, and for your two pieces of information in your note
‘about the sexes of the Batchian Butterfly and about the
Longicorn Beetle.—?
With many thanks, pray believe me
Yours very sincerely
Cu. DARWIN
10.
Jan. 16th[, 1868.] Down.
BROMLEY.
Kent, S.E.
My DEAR Mr TRIMEN
I really do not know how to thank you enough for
all the great trouble which you have taken for me.—
I never saw anything so beautiful as your drawings.?
I have examined them with the microscope!! When
I asked for a sketch I never dreamed of your taking
so great trouble—Your letter and Proof-sheet give me
exactly and fully the information which I wanted. I am
very glad of the description of the ocellus in the
S. African Saturnidew:* I had no idea it was so com-
1 In The Descent of Man (1874), 250, Darwin quotes A. R.
Wallace's observation, doubtless supplied to him by Trimen, and
here referred to, that the female of Ornithoptera croesus was
commoner and more easily caught than the male. Mr. Trimen
thinks that this must be the ‘ Batchian Butterfly’. On p. 294
n. 68 Darwin states that he had been informed by Trimen that
the male of a species of the Lamellicorn genus Trichius is more
obscurely coloured than the female. Trimen’s name is not men-
tioned in connexion with the similar relationship recorded for
certain Longicorn beetles on pp. 294, 295.
* The drawings were illustrations of the extreme variation in the
development of the eye-spots on the wings of Cyllo (Melanitis) leda.
Darwin referred to these and figured some of them in Descent of
Man (1874), 428, 429.
* Darwin is here evidently alluding to the description given
him by Trimen of the ‘8. African moth (G@Gynanisa isis), ailied
to our Emperor moth, in which a magnificent ocellus spire 88
nearly the whole surface of each hinder wing’.— Descent of Man
(1874), 428,
234 #$DARWIN’S LETTERS TO R. TRIMEN
plex.—If you know of any case in Lepidoptera of ocelli
regularly confined to the male,’ I sh‘ much like to hear
of it, as it would illustrate a little better the case of the
peacock, which has often been thrown in my teeth.—
I doubt whether such cases exist, and if I do not hear
I will understand that you know of no such case.
Again let me thank you cordially for your great kind-
ness, and I remain,
Yours very sincerely
Cu. DARWIN
1 oe
Written by Mrs. Darwin, signed by Charles Darwin. 5
Down. -
BROMLEY. ?
Kenp, S.E. ij
Feb 12 [1868.] ;
My DEAR MR TRIMEN
I shall be very happy to put my name down for
your brother’s book and he can hand over the enclosed
paper to Hardwick.” ;
Since you were here I have become much interested
on the relative numbers of the males and females of all
animals. I am particularly anxious for other cases like
that from [A. R.] Wallace which you gave me of females
in excess ;* or to know that such cases are rare. If you
can, I am sure you will aid me.* Do you give many
1 Mr. Trimen informs me that he was unable to discover any
such case.
2 Mr. Trimen thinks that the book must have been the Flora
of Middlesex (octavo, London : ee written and published by
Henry Trimen and Sir William Thiselton-Dyer.
3 See p. 233 n. 1.
* This letter enclosed a slip of paper which is evidently Trimen’s
copy of the list sent by him in reply to Darwin's inquiry. It con-
tains a full list of nineteen species of South African butterflies in
which males are more numerous than females, and of three species
a
SEX RELATIONSHIPS OF INSECTS: 1868 235
.
instances in your book on 8. African butterflies, of males
in excess. I remember writing down one or 2 cases
which you gave me.
Believe me
Yours very sincerely
Cu. DARWIN
12.
Feb, 21st [1868.] Down.
BROMLEY,
Kent. S.E.
My DEAR MR TRIMEN
You are always most kind in aiding me. The
argument of the Lasiocampa? strikes me as very good—
but what an intricate subject it is !—I have had excellent
letters from Stainton and Bates. The latter is much
staggered—Have you ever heard or observed other
eases like the Lasiocampa. I think I have seen in
England many Butterflies pursuing one.— But here comes
a doubt may not the same male serve more than one
female. I think I will write to Dr. Wallace of Col-
chester.2—
in which the females are apparently the more numerous. These
numbers are quoted by Darwin in Descent of Man, &c. (1874), 250.
? Mr. Trimen has kindly given me the following note :—
‘E. Blanchard (in his Métamorphoses, Meurs et Instincts des
Insectes) had attributed to some special and peculiar sense the
wer exhibited by many males among moths of discovering the
istan t and concealed females of their respective species. 1 con-
tended that it could only be the sense of smell that was brought
to bear in such cases, instancing my own experience in the case of
the on ‘Oak Eggar’ (Lasiocampa quercus), where the males
assembled to an empty box in my pocket which had contained
a virgin female on the tg day.’ The observation is referred
bs so 7 ae of Man (1874), 252. See also Darwin's argument in
e r , p. .
® The experience of Dr. A. Wallace with the large silk-producing
moths is quoted in several places in the Descent of Man, &c.
236 DARWIN’S LETTERS TO R. TRIMEN
My women-kind have insisted on coming to London
for all March, much to my grief; but I shall get some
good, for I shall see some of my friends, and you amongst
the number.—
With very sincere thanks
Believe me
Yours very sincerely
Cu. DARWIN
I shall go doggedly on collecting facts through the
animal kingdom, and possibly at the end some little
light may be acquired.—I am getting some of the chief
domestic animals tabulated.
In the last sentence of the following letter
Darwin was referring to the evening of March 5,
1868, when Trimen read his remarkable and
important paper, published in the early part
of the following year: ‘On some remarkable
Mimetic Analogies among African Butterflies,’ !
Bates’s classical paper on Mimicry (1862), re-
ferred to on pp. 122-6, was concerned with
tropical American butterflies and moths. A. R.
Wallace’s paper ‘On the Phenomena of Varia-
tion and Geographical Distribution as illustrated
by the Papilionide of the Malayan Region’?
(1866) dealt with the same subject as illustrated
by butterflies in the tropical East. Trimen’s
paper completed the great series by extending
the hypothesis of Mimicry to the African con:
tinent. The chief example considered in the
paper, that of Papilio dardanus (merope), was by.
1 Trans. Linn. Soc. Lond., xxvi. 497-522.
2 Trans. Linn. Soc. Lond., xxv. 1-71,
TRIMEN’S DISCOVERIES IN MIMICRY 287
far the most complex and difficult to interpret
of any in the world. When, in this masterly
memoir, he had at length unravelled the tangled
relationships, three ‘species’, up to that time
regarded as entirely distinct, had been sunk as
the three different mimetic females of a single
non-mimetic male, then known as a fourth
‘species’, Trimen’s conclusions were not con-
firmed by the supreme test of breeding until
1902, and all three mimetic forms found in one
locality were not bred from the eggs of a single
parent until 1906.!
One of the principal opponents of Trimen’s
conclusions was the late W. C. Hewitson, who
said: ‘it would require a stretch of the imagina-
tion, of which I am incapable, to believe that...
P. merope . .. indulges in a whole harem of
females, differing as widely from it as any other
species in the genus .. .’* However, shortly
after he had written the above sentence Hewitson
received from one of his own collectors this
very male taken paired with one of the mimetic
females.*
My friend Mr. Harry Eltringham has recently
pointed out to me a passage, marked by much
confusion of thought, in Hewitson’s Exotic Butter-
flies, which might be read as an anticipation
1 See ‘dardanus’ in index of Essays on Evolution (1908), 414;
also Plate XXIII in Trans. Ent. Soc. Lond. (1908), 427-45.
'® Trans. Ent. Soc. Lond. (1874:, 187.
° BE. M. M, (Oct., 1874), 113.
* London, 1862-66, III: text of plate ‘Nymphalide. Diadema iii. :
(pages unnumbered).
238 $$DARWIN’S LETTERS TO R. TRIMEN
of Fritz Miiller’s earlier suggestion that Mimiery
may be due to Sexual Selection (see pp. 127-8).
I do not think that the words really bear this
interpretation, but even if they do, it is obvious
that a suggestion intended to be taken as a joke
cannot be looked upon as a serious anticipation !
Inasmuch as Hewitson makes special reference
to the three papers of Bates, Wallace and Trimen,
it is not inappropriate to quote his criticisms
at this point.
After describing some of the wonderful forms
that would now be placed in the African genus
Pseudacraea mimetic of the Acraeine genus Pla-
nema from the same localities, Hewitson proceeds
to remark :— .
‘This strange resemblance to each other of distant
and very distinct groupes, which forms the romance of
natural history, has afforded wonder and delight to every
naturalist, and will do so to the end of time, the more
so because of its mystery, unless some much better ex-
planation is offered than that proposed by Darwin and
his followers, because, unluckily for them, it is just those
species which superficially bear the closest resemblance
to each other that differ most in their fundamental
structure.’
The objection urged by Hewitson is of course
the strongest of all reasons in favour of the views
he is attacking. Such fundamental differences
exclude an interpretation of resemblance based
simply on affinity. It is well that this important
statement should be proclaimed by an opponent
+
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:
THE TESTIMONY OF AN OPPONENT 2389
of the theory of Mimicry. It is also well that
he should say of the ‘ great leading aristocratic’
groups which are resembled by other butterflies—
Danais, Acraea, ‘ Heliconidae’ (including under this
head Ithomiinae and Danainae as well as true
Heliconinae ') :—
‘One of the most marvellous things in this repre-
sentative system is that the great groupes are not only
imitated at home, but that the stragglers from two of
them in other lands have their mimics as well ; and in
the great South American groupe, the Heliconide, the
butterflies of several genera, completely different in their
neuration, are inseparable by the unaided sight.’
It would be hardly possible to produce better
indirect evidence of some special quality in the
chief models than that afforded by the resem-
blances to them formed afresh when stragglers
have wandered into other lands. Section VI
of the present work is largely concerned with
one striking example of the mimetic resemblance
by indigenous New World species of invading
Danaines from the Old World. Hewitson for
a most singular reason rejects the conclusion
that the groups in question are specially pro-
tected, and concludes by making the jocular
suggestion to which Mr. Eltringham directed
my attention :—
‘ Naturalists, Wallace, Bates, and Trimen, who have
each studied one of these great groupes in their native
land, tell us that they exude a liquid of an offensive
* See pp. 152-4.
240 DARWIN’S LETTERS TO R. TRIMEN
smell. We have, however, no right to conclude that
what may be unpleasant to us is not to them a sweet-
smelling royal unction. May not all the imitators of
these scented aristocrats be simply votaries of fashion,
apeing the dress of their superiors, and, since the females
take the lead, “naturally selecting ” those of the gayest
— colours ?’
Hewitson in the first part of the above para-
graph assumes that the liquid is considered to
be offensive to the insects themselves, whereas of
course it is believed to protect against insect-eating
animals. In the last part I do not think he uses
the word ‘ naturally’ when he means ‘sexually ’,
for the sake of the little play upon the former
word. I think by the words ‘females take the
lead’ Hewitson refers to the greater prevalence
and perfection of female Mimicry, and that he
only intended to convey the facetious suggestion.
of conscious and deliberate imitation. |
To return to Trimen’s paper, it is hardly
surprising that a memoir containing such novel
and startling conclusions should have been heard
by a hostile audience, and my friend tells me
that ‘Darwin’s congratulations were of immense
comfort, as the large meeting was. for by far
the greater part opposed and discouraging’.
Darwin’s keen interest in Bates’s paper. has
been shown on pp. 123-6, the part he took in
encouraging Fritz Miiller in his successive amend-
ments of the Batesian Hypothesis, on pp. 126-9 ;
but the following letter is the first evidence I
a
DARWIN AND TRIMEN’S PAPER: 1868 241
have come across of his personal interest in the
immensely important contribution made by Roland
Trimen.
18.
Monday 4, CHESTER PLAcr?
[ Mar. 20, 1868] REGENTS Park
N.W.
My DEAR Mr TRIMEN
Would it suit you to come and lunch here at
1. oclock on Friday or Saturday, or indeed almost any
day; or if luncheon-time does not suit you, if you will
you will [sic] tell me at what hour you will call I will be
at home.—I hear that you had a brilliant night at Linn.
Soe. and I regretted so much that I could not come.
Yours very sincerely
Cu. DARWIN
14,
Saturday [1868] 4 CHESTER PLACE
N.W.
My DEAR MR TRIMEN,
Tuesday w‘ suit me, but another man (Mr. Blyth *)
is coming to lunch on that day, and as you know that
I am not up to more than an hour's talk, I sh‘ see less
of you; so if equally convenient and I do not hear to
contrary, I will name Wednesday at 1 oclock.
Very many thanks for your information in note.—
Yours very sincerely
C. DaRwINn
' The house of Mrs. Darwin’s sister, Miss Elizabeth W. ood,
® See More Letters, i. 62 n., for an account of this naturalist,
R
242 DARWIN’S LETTERS TO R. TRIMEN
15.
April 14th—[1868] Down.
BROMLEY.
Kent. S.E.
My DEAR Mr TRIMEN
It is very kind of you to take the trouble of
making so long an extract, which I am very glad to
possess, as the case is certainly a very striking one.
Blanchard’s argument about the males not smelling the
females, because we can perceive no odour, seems to me
curiously weak. It is wonderful that he sh* not have
remembered at what great distances Deer and many
other animals can scent the cleanest man.1—
Many thanks for your Photograph, and I send mine,
but it is a hideous affair—merely a modified, hardly an
improved, Gorilla.—
Mr [H.] Doubleday has suggested a capital scheme
for estimating the number of sexes in Lepidoptera, viz
by a German List, in which in many cases the sexes are
differently priced.? With Butterflies, out of a list of
about 300 Sp. and Vars. 114 have sexes of different prices,
and in all of them, with one single exception, the male
is the cheapest. On an average judging from price for
every 100 females of each species there ought to be 148
males of the same species.—So I firmly believe that you
field collectors are correct.—Nearly the same result with
Moths.
1 The ‘extract’ probably refers to an account of the males
of the Oak Eggar moth assembling to a box that had contained the
female (see p. 235 7. 1). Blanchard’s argument was revived in
1894 by Prof. F. Plateau, who, finding the taste (‘saveur réelle °) of
the larva, pupa, and imago of the Magpie moth (Abraxas grossu-
lariata) to be somewhat pleasant to his own palate, concluded
that it was not distasteful to insectivorous animals. This con-
clusion is opposed by the present writer in Trans. Ent. Soc. Lond.
(1902), 405-14.
2 Quoted by Darwin in Descent of Man, &c. (1874), 252.
SEX RELATIONSHIPS OF INSECTS: 1868 248
I sincerely wish you health, happiness and success in
Nat. History in 8. Africa. I should have much liked to
have asked you, if you could have spared time, to come
down here for a day or two; but Mrs. Huxley is coming
here in a few days with all her six children and nurses,
for healths sake, and stop some weeks. And our House
will be, with others, so absolutely full, that today we
have had to tell our Brother-in-law, that we cannot
possibly receive him.—
Most truly do I thank you for your great kindness in
aiding me in so many ways. Yesterday I was working
in much of your information.—
Believe me
Yours very sincerely
C. DARWIN
16.
July 24th [1871] Down,
BECKENHAM,
KENT.
My DEAR MR TRIMEN
I am much obliged for your long and interesting
letter. You asked me whether I have any notion about
the meaning of moths ete flying into candles, and birds
against light-houses.—I have not.—I have looked at the
case as one of curiosity, which is very strong with the
higher animals, and I presume even with insects. A light
is a very new object, and its distance cannot be judged,
but how it comes that an insect is so stupid as to go on
flying into the same candle I cannot conceive. It looks
as if they were drawn towards it.—Sir C. Lyell, I re-
member, made years ago the difficulty greater by asking
me, what stops all the moths in the world flying every
moon-light night up to the moon, or as near as they could
get.—Perhaps they have instinctively learnt that this
cannot be done.—
R2
244 DARWIN’S LETTERS TO R. TRIMEN
With respect to humour, I think dogs do have it, but
it is necessarily only of a practical kind. Everyone
must have seen a dog with a piece of a stick or other
object in his mouth, and if his master in play tries to
take it away, the dog runs with prancing steps a few
yards away, squats down, facing his master, and waits
till he comes quite close and then jumps up and repeats
the operation,—looking, as if he said, “ you are sold ”.—
I have many letters to write so pray excuse brevity.
—My book has been very successful as far as sale has been
concerned, and has hitherto been in most cases treated
very liberally by the press.—My notions on the moral
sense have, however, been much reprobated by some
and highly praised by others.—I have no news to tell,
for I have seen hardly any one for months.—
I am extremely sorry to hear that you are no freer
of official duties, for I feel sure if you had more leisure
and especially if you lived in the country, you would
make some grand new observations.—
With every good wish—
Pray believe me
Yours sincerely
Cu. Darwin
17.
Written by Sir George Darwin, signed oy
Charles Darwin.
Down
BECKENHAM
My DEAR Mr. TRIMEN, Thursd. July 27. 71
I was much surprized to receive your letter and
I am sorry to hear of the cause of your hurried return
to England.’—
1 In consequence of the death of his father in March, 1871,
—-_ = -
DARWIN ON ‘DESCENT OF MAN’: 1871 246
I have been a good deal out of health of late and we
have taken Haredene! for a month in order that I may
get a little rest. We start tomorrow morning. I shall
have very great pleasure in seeing you there after your
return from Edinburgh. I am sorry to say that I cannot
ask you to sleep with us as we shall have no beds to
spare ;—but I suppose from what you say that you will
be staying in the neighbourhood. Many thanks for the
Review which I will read in the course of the day.?
Believe me
Yours very sincerely
CHARLES DARWIN
18.
From Mrs. Darwin.
HAREDENE ® Tuesday
[Jul. 28-Aug. 25, 1871]
Dear MR TRIMEN
I am very sorry to say that Mr Darwin has been
so unwell (ill I may say) that we are hastening our return
home as soon as possible. He is quite unequal to seeing
you which he very much regrets.
Our stay in this charming place is a great disappoint-
ment, though I hope he will reap the benefit of the rest
afterwards. He desires me to repeat how very sorry he
is not to be able to see you
believe me
yours very truly
Emma DARWIN
1 Mr. Francis Darwin informs me that Haredene is near Albury
in rg
* Mr. Trimen thinks that the Review spoken of was a notice of
the Descent of Man, &c., contributed by him to the Coupe Monthly
Magazine in June, 1871.
® See the above », 1.
246 DARWIN’S LETTERS TO R. TRIMEN
19.
Nov. 18th [1871] Dowy,
BECKENHAM, KENT.
My DEAR Mr TRIMEN
I write one line to say how sorry I am not to see you
before your return to the Cape,' which I presume will
be soon. But I cannot get my head steady enough to
see anyone. I have just returned from a visit to my
sister for a week, but I was forced to spend nearly all
the day in my bed-room.—
I read with much interest some little time ago your
paper on Geographical Distribution of Beetles; and
agreed, I believe, with all your general remarks.2— _
I wish you all success in your future researches and
remain
_ Yours very sincerely
Cu. DARWIN
If on the point of starting do not trouble yourself to
answer this.—
1 The letter was received Jan. 11, 1872, after Trimen had
returned to the Cape.
? The paper referred to is:
Notes on the Geographical Distribution and Dispersion of Insects ;
chiefly in reference to a paper by Mr. Andrew Murray, F.L.S., ‘ on the
Geographical Relations of the chief Coleopterous Faune’—-By Roland
Trimen, F.L.S., &c.—Linn. Soc. Journal. —Zool. xii (1871), 276-84.
Murray in a very dogmatic way had in his elaborate memoir
endeavoured to account for the greater part of the difficulties
presented by the known existing distribution of animals and
plants over the globe by the simple explanation of ‘continuity of
soil at some former period’. Trimen in his papér insisted on the
more important methods of dispersal always at work, and traversed
several of the author's statements, especially as regards oceanic
islands, which had been treated by Murray as obviously surviving
portions of otherwise vanished continental lands.
APPENDIX A
CHARLES DARWIN AND THE
HYPOTHESIS OF MULTIPLE ORIGINS
I nave thought it of interest to consider in
some detail Darwin’s attitude towards a single
one of the examples (pp. 45, 46) in which his
sure judgement shines forth so conspicuously
among his seniors, contemporaries and successors
alike. |
I select the idea that species or groups of
species had arisen from ‘ multiple’ (or ‘ polyphyl-
etic’) origins—a hypothesis very fashionable,
during one brief period, both in America and
on the Continent.
According to this hypothesis, two or more
groups of animals were supposed to have arisen
independently, perhaps in different countries,
and subsequently by ‘convergence’ to have be-
come one. The most extreme development of
this view would be the incredible belief that
a single species might be formed from separate
bodies of individuals, arising independently from
very different lines of descent, but subsequently
fusing into an interbreeding community. Long
before this idea became popular, it had been
thought over by Darwin and seen to be worth-
248 APPENDIX A
less. The following references to the subject
are to be found in his correspondence with
Sir Joseph Hooker in 1854 and 1856, years
before the publication of the Origin :—
1854, July 2.—‘I am glad to hear what you-say about
parallelism: I am an utter disbeliever of any parallelism
more than mere accident.’ '
1856, July 13.—‘You say most truly about multiple
creations and my notions. If any one case could be proved,
I should be smashed ; but as I am writing my book, I try
to take as much pains as possible to give the strongest cases
opposed to me, and often such conjectures as occur to me.’*
1856, July 19.—‘. .. it is absolutely necessary that. I
should discuss single and double creations, as a very crucial
point on the general origin of species, and I must confess,
with the aid of all sorts of visionary hypotheses, a very
hostile one.’ ®
The above-quoted sentences sum up very
briefly Darwin’s conclusion that evolution as he
conceived of it implied that each species had
appeared once only in a single continuous area
and had then tended to spread from this as from
a centre—implied in fact the soundness of the
belief in what were then called ‘single centres
of creation’. His arguments in favour of this
conviction are given in great detail in the first
edition of the Origin: first in chapter X, sup-
porting the conclusion,—‘it is incredible that
individuals identically the same should ever have
been produced through natural selection from
1 More Letters, i. 77. 2 More Letters, i. 95.
3 More Letters, ii. 249.
DARWIN AND MULTIPLE ORIGINS 249
parents specifically distinct’! ; secondly, in chap-
ters XI and XII, the vast array of facts which
are consistent with the belief in ‘ single centres of
creation’, and serve to explain the great apparent
difficulties,
Sir Charles Lyell had also arrived at the firm
conviction that species had spread from single
centres, and, within a few days of Darwin’s
expression of the same conviction in July, 1856,
he also was writing to Hooker and telling of
his unnecessary fears :—
1856, July 25.—‘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.’?
It is clear that Darwin heard of Lyell’s ap-
prehensions and was referring to them in the
two following passages in letters to Hooker :—
1856, July 30.—‘I cannot conceive why Lyell thinks
such notions as mine or of ‘ Vestiges’ will invalidate
specific centres.’ *
1856, Aug. 5.—‘ 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 !’ *
When, however, the Origin had appeared, and
Lyell was for a time resisting its appeal, he
? Origin of Species (1859), 352.
® Life and Letters, ii, 83. ae from Life of Sir Charles Lyell,
ii, 216. ® Ibid., 81. Ibid., 82.
250 APPENDIX A
was not unwilling to contemplate multiple
centres with a vengeance; for he put forward
as a difficulty the fact that mammals had not
arisen independently on oceanic islands. Refer-
ring to this point, Darwin wrote to him (Sept-
ember 1, 1860) as follows :—
‘ With respect to a mammal not being developed on any
island, besides want of time for so prodigious a development,
there must have arrived on the island the necessary and
peculiar progenitor, having a character like the embryo of
a mammal; and not an already developed reptile, bird or
fish. We might give to a bird the habits of a mammal, but
inheritance would retain almost for eternity some of the
bird-like structure, and prevent a new creature ranking
as a true mammal.’ !
Lyell does not appear to have been convinced
by the argument, and Darwin wrote again on
September 23, 1860:
‘I have a very decided opinion that all mammals must
have decended from a single parent [species]. Reflect on the
multitude of details, very many of them of extremely little
importance to their habits (as the number of bones of the
head, &¢., covering of hair, identical embryological develop-
ment, &c. &c.). Now this large amount of similarity I must
look at as certainly due to inheritance from a common stock.
I am aware that some cases occur in which a similar or
nearly similar organ has been acquired by independent acts
of natural selection. But in most of such .cases of these
apparently so closely similar organs, some important homo-
logical difference may be detected.’ ”
Lyell had argued that, just as man would now
keep down any new man that might be developed,
so the bats and rodents of oceanic islands may
1 Life and Letters, ii, 335. * Le., ii. 841.
—
:
J
J
DARWIN AND MULTIPLE ORIGINS 251
have prevented the independent origin of other
mammals. To this argument Darwin replied :
‘I know of no rodents on oceanic islands (except my
Galapagos mouse, which may have been introduced by man)
keeping down the development of other classes, Still much
more weight I should attribute to there being now, neither
in islands nor elsewhere, [any] known animals of a grade of
organisation intermediate between mammals, fish, reptiles,
&c., whence a new mammal could be developed. If every
vertebrate were destroyed throughout the world, except our
now well-established reptiles, millions of ages might elapse
before reptiles could become highly developed on a scale
equal to mammals; and, on the principle of inheritance,
they would make some quite new class, and not mammals ;
though possibly more intellectual !’’
Many years later, in a letter to the Duke of
Argyll (September 23, 1878), Darwin gave a
more complete answer to the extreme supporters
of the hypothesis of multiple origins, at the same
time refuting the opinion—not uncommon even
at the present day—that a terrestrial species such
as man may exist on Mars or on some other
body outside the earth. For Darwin shows in
the following letter that, in order to produce the
same species twice over, the same material must
have been subject to the same selection at every
stage, right back to the unknown starting-point
of organic evolution.
‘ As far as I can judge, the improbability is extreme that
the same well-characterised species should be produced in
two distinct countries, or at two distinct times. It is
certain that the same variation may arise in two distinct
places, as with albinism or with the nectarine on peach-trees.
? Sept. 23, 1860. Life and Letters, ii, 344.
252 APPENDIX A
But the evidence seems to me overwhelming that a well-
marked species is the product, not of a single or of a. few
variations, but of a long series of modifications, each modi-
fication resulting chiefly from adaptation to infinitely complex
conditions (including the inhabitants of the same country),
with more or less inheritance of all the preceding modifica-
tions. Moreover, as variability depends more on the nature
of the organism than on that of the environment, the
variations will tend to differ at each successive stage of
descent. Now it seems to me improbable in the highest
degree that a species should ever have been exposed in two
places to infinitely complex relations of exactly the same
nature during a long series of modifications. An illustration
will perhaps make what I have said clearer, though it
applies only to the less important factors of inheritance and
variability, and not to adaptation—viz., the improbability of
two men being born in two countries identical in body and
mind. If, however, it be assumed that a species at each
successive stage of its modification was surrounded in two
distinct countries or times, by exactly the same assemblage
of plants and animals, and by the same physical conditions,
then I can see no theoretical difficulty [in] such a species
giving birth to the new form in the two countries.’!
The Duke misunderstood the letter, for he used
it as evidence to support his assertion ‘that
Charles Darwin assumed mankind to have arisen
at one place, and therefore in a single pair’.
It is obvious that no such conclusion follows
from Darwin’s argument; but in order to settle
the question once for all, Sir William Thiselton-
Dyer published a letter? in which Darwin makes
the following statement :
1 Nature, xliii. 415. At the conclusion of the letter Darwin
refers his correspondent to p. 100 of the sixth ed. of the Origin. See
also More Letters, i. 377, 378. .
* Nature, xliii. 5385. See also More Letters, i. 378-81.
DARWIN AND MULTIPLE ORIGINS ~— 253
‘I dispute whether a new race or species is necessarily, or
even generally, descended from a single or pair of parents.
The whole body of individuals, I believe, become altered
together—like our race-horses, and like all domestic breeds
which are changed through “unconscious selection” by man.’
This passage was written (Nov. 25, 1869) in a
letter to G. Bentham as a criticism of the follow-
ing passage in his presidential address to the
Linnean Society on May 24, 1869:
‘We must also admit that every race has probably been
the offspring of one parent or pair of parents, and conse-
quently originated in one spot.’
The Duke of Argyll had inverted Bentham’s pro-
position, as pointed out by Sir W. Thiselton-
Dyer.
On this remarkable page in the history of
thought we see how Darwin, by sure and pene-
trating genius, rises to heights far beyond those
attained by the men of his own and later days.
We see Lyell in fear and doubt lest his cherished
belief in ‘single centres of creation’ should be
endangered by the one man who held the same
belief on much stronger grounds. We find the
great geologist, at a later stage, ready to give up
his belief if he can thereby obtain a weapon
against evolution; and observe, in Darwin’s
answer to him and to the Duke of Argyll, an
entire grasp of the problem conspicuously want-
ing in those authorities who expressed, at a
later date, an ill-founded enthusiasm for the
worthless hypothesis of multiple origins.
254
APPENDIX B
DARWIN AND EVOLUTION BY MUTATION
I wave spoken on pages 48 and 44 of the
frequency with which Darwin, between 1860
and 1880, was brought back by others to a motive
cause of evolution based on ‘sudden jumps’, or
_ ‘monstrosities’, on ‘large’, ‘ extreme’, and ‘ great
and sudden’ variations. Such views were con-
tinually urged upon him by ‘his correspondents,
and by reviews and criticisms of his work’. It
is I think of interest, in relation to the biological
fashions of the day, to show by many examples
how firmly he met such suggestions whenever they
were made to him. I therefore append the follow-
ing quotations from his letters to those on pages 48
and 44 and to be found in the Quarterly Review ' : —
(1) 1860. ‘... he [Harvey] assumes the permanence of
monsters, whereas, monsters are generally sterile, and not
often inheritable.’ ?
(2) 1860. ‘It would take a good deal more evidence to
make me admit that forms have often changed by saltwm.’*
(8) 1860. ‘Although I fully agree that no definition can
be drawn between monstrosities and slight variations (such
as my theory requires), yet I suspect there is some dis-
tinction. Some facts lead me to think that monstrosities
supervene generally at an early age; and after attending to
the subject I have great doubts whether species in a state of
nature ever become modified by such sudden jumps as
would result from the Natural Selection of monstrosities,’ *
1 July, 1909; 10-12, 25, 26.
? To Sir Charles Lyell, Feb. 18, 1860.—Life and Letters, ii. 275.
5 To Sir Joseph Hooker, Feb., 1860.—Jbid., 274.
* To Maxwell Masters, April 13, 1860.—More Letters, i. 147, 148.
ole de
mine! the
4
9
t
ttt tiie ee
DARWIN AND MUTATION 255
(4) 1860. ‘About sudden jumps: I have no objection to
them—they would aid me in some cases. All I can say is,
that I went into the subject, and found no evidence to make
me believe in jumps ; and a good deal pointing in the other
direction.’ '
(5) 1871. ‘... Ihave now almost finished a new edition
of the Origin, which Victor Carus is translating. There is
not much new in it, except one chapter in which I have
answered, I hope satisfactorily, Mr. Mivart’s supposed diffi-
culty on the incipient development of useful structures. I
have also given my reasons for quite disbelieving in great
and sudden modifications.’ ’
(6) 1873. ‘It is very difficult or impossible to define
what is meant by a large 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,’ *
(7) 1880. ‘It is impossible to urge too often that the
selection from a single varying individual or of a single
varying organ will not suffice.’ *
(8) 1880. Finally the letter to Nature, dated
November 5, 1880, was one of the strongest
things ever written by Darwin. It originally
contained a passage which the writer omitted
on the advice of his most combative friend
Huxley. The two grounds on which Darwin
based his emphatic protest are stated in the
following passage. A mutationist conception of
evolution based on ‘extreme variation’ is the
1 To W. H. Harvey, August, 1860.—More Letters, i. 166.
2 To E. Hiickel, December 27, 1871.—More Letters, i. 385.
* To R. Meldola, Au 13, 1873.—More Letters, i, 350.
* To A. R. Wallace, January 5, 1880.— More Letters, i. 384.
256 APPENDIX C
first of them ; the assumption that he had made
Natural Selection the sole motive cause of evolu-
tion forms the second :
‘I am sorry to find that Sir Wyville Thomson does not
understand the principle of Natural Selection, as explained
by Mr. Wallace and myself. If he had done so, he could
not have written the following sentence in the Introduction
to the Voyage of the Challenger: “The character of the
abyssal fauna refuses to give the least support to the theory
which refers the evolution of species to extreme variation
guided only by Natural Selection.” ’'
9
4
4
APPENDIX C
WORK ESSENTIAL FOR DARWIN’S
HEALTH AND COMFORT)
Tue alteration in tastes and interests which
Darwin described in himself has been wrongly
interpreted. The errors have been widely spread
and are repeated by able and influential writers
even at the present day.? It is important in
justice to scientific men as a body and especially
to Darwin himself to show by repeated evidence
the true cause of the changes set down in the
autobiography. I have therefore added a’number
of quotations from Darwin’s letters to the evi-
dence brought forward on pages ‘59-66 and
yielded by the correspondence with Roland Trimen
on pages 218 to 246. The two passages written
in 1859 refer to the preparation of the Origin
of Species :—
? More Letters, i. 388, See Nature, Nov. 11, 1880, p. 32.
2 See pp. 79-83. *
DARWIN’S HEALTH AND WORK 257
1859. ‘I have been so poorly, the last three days, that
I sometimes doubt whether I shall ever get my little
volume done, though so nearly completed .. .’*
1859. ‘... I can truly say I am never idle; indeed,
I work too hard for my much weakened health ; yet I can
do only three hours of work daily, and I cannot at all see
when I shall have finished.’ *
1864. ‘I honour your wisdom at giving up at present
Society for Science. But, on the other hand, I feel it in
myself possible to get to care too much for Natural Science
and too little for other things.’*
1865. ‘What a wonderful deal you read; it is a horrid
evil for me that I can read hardly anything, for it makes
my head almost immediately begin to sing violently. My
good womenkind read to me a great deal, but I dare not ask
for much science, and am not sure that I could stand it.’*
1868. ‘It is really a great evil that from habit I have
pleasure in hardly anything except Natural History, for
nothing else makes me forget my ever-recurrent uncomfort-
able sensations.’°
1868. The concluding sentences of the fol-
lowing passage are quoted on pages 64 and 65,
but it is of interest to print them again together
with the words that led up to them. The passage
first graphically describes the changes in Darwin's
mind, and then clearly explains and interprets
what has been so often and so injuriously mis-
understood.°
‘I am glad you were at the ‘ Messiah’, it is the one
thing that I should like to hear again, but I dare say I
' To J. D. Hooker: March 5.— Life and Letters, ii. 149.
2 To Asa Gray, Apr. 4.—Life and Letters, ii. 155.
* To T. H. Huxley, April 11.—More Letters, i. 247.
* To J. D. Hooker, Sept. 27.— Life and Letters, iii. 40.
5 To J. D. Hooker, Feb. 3.—Life and Letters, iii. 75.
* See especially pp. 79-83.
8
258 Fe APPENDIX D
should find my soul too dried up to appreciate it as in old
days ; and then I should feel very flat, for it.is a horrid bore
to feel as I constantly do, that I am a withered leaf for
every subject except Science. It sometimes makes me hate
Science, though God knows I ought to be thankful for such
a perennial interest, which makes me forget for some hours
every day my accursed stomach.’ !
1869. ‘I have been as yet in a very poor way; it seems
as soon as the stimulus of mental work stops, my whole
strength gives way.’?
1876. ‘—and then home to work, which is my sole
pleasure in life.’ *
1878. ‘Thank Heaven, we return home on Thursday,
and I shall be able to go on with my humdrum work, and
that makes me forget my daily discomfort.’ *
APPENDIX D
DE VRIES’S ‘FLUCTUATIONS’ HEREDITARY AC-
CORDING TO DE VRIES, NON-TRANSMISSIBLE
ACCORDING TO BATESON AND PUNNETT
Since the note on p. 49 was written I have
had the opportunity of reading the whole of the
Presidential Address to the Zoological Section at
Winnipeg, a copy having been kindly sent to me
by my friend Dr. Shipley. I find that the account
of fluctuations which is so diametrically opposed
to that given by the author of this term in its
technical sense, is adopted from Mr. R. C. Punnett’s
little work Mendelism (2nd edit., Cambridge, 1907),
a fact omitted from the necessarily abridged
1 To J. D. Hooker, June 17.—Life and Letters, iii. 92.
2 To J. D. Hooker, June 22.—Life and Letters, iii. 106.
5 To G. J. Romanes, May 29.—More Letters, i. 364.
* To G. J. Romanes, Aug. 20.—More Letters, ii. 48.
ss - «
-
BATESON ON ‘FLUCTUATIONS’ 259
report in the Times. While Dr. Shipley’s words,
quoted on p. 49, are perhaps a little more precise
than those of Mr. Punnett,! Professor Bateson’s
statement is more definite still :-—
‘For the first time he [de Vries] pointed out the clear
distinction between the impermanent and non-transmissible
variations which he speaks of as fluctuations, and the per-
manent and transmissible variations which he calls
mutations.’ *
Professor Bateson and Mr. Punnett are the
chief exponents of de Vries in this country. It
may be assumed, I think, that de Vries reaches
the British public through the 85 pages of
Mr. Punnett’s booklet rather than through the
847 pages of the only volume by the Dutch
botanist which has until now appeared in the
English language. The unfortunate misrepre-
sentation of de Vries is therefore certain to have
led, and, in spite of this correction, is still, I fear,
certain to lead, to utter confusion of thought in
a subject only too likely to become obscure
without adventitious assistance.
The extent of this unintentional, but very
serious, misrepresentation of an authority by his
exponent, can be most clearly shown by printing
together passages by de Vries and Bateson from
1 *Of the inheritance of mutations there is no doubt. Of the
transmission of fluctuations there is no very strong evidence. It is
therefore reasonable to regard the mutation as the main, if not
the only, basis of evolution.’ (p. 72.)
; Mendel’s pa 90 of gary, = Cambridge (1909), 287.
Species a arieties: their Origin by Mutation. Chicago and
London. Second edit., 1906.
82
260 APPENDIX D
the same volume—Darwin and Modern Science
(Cambridge, 1909). The following passage on
pp. 83 and 84 is written by de Vries :—
‘Thus we see that the theory of the origin of species by
means of natural selection is quite independent of the
question, how the variations to be selected arise. They
may arise slowly, from simple fluctuations, or suddenly, by
mutations; im both cases natural selection will take hold of
them, will multiply them if they are beneficial, and in the course
of time accumulate them, so as to produce that great diversity
of organic life, which we so highly admire.’
On p. 95, only eleven pages further on, we
find the following statement made by Professor
Bateson, a statement which entirely contradicts
the words I have italicized in the quotation from
de Vries :—
‘First we must, as de Vries has shown, distinguish real,
genetic, variation from fluctwational variations, due to en-
vironmental and other accidents, which cannot be trans-
mitted.’
I freely grant that de Vries’s statement, taken
as a whole, does not appear to be very consistent
with much that he has written.! He is stating
alternative views as to the origin of selected
variations, but the italicized words could never
have been written by one who did not maintain
the hereditary transmission of fluctuations; and
this belief is, as will be shown below, implied in
many another passage, to be found with sufficient
labour in de Vries’s voluminous and somewhat
obscurely written treatises.
1 See also Quarterly Review (July, 1909), 30.
iia sn ell .
THE THREATENED CONFUSION 261
In a striking metaphor Professor Bateson has
objected to the use of the term ‘variation’ to
express certain different forms presented by the
individuals of a species: ‘We might as well,’ he
says with a fine scorn, ‘use one term to denote
the differences between a bar of silver, a stick of
lunar caustic, a shilling, or a teaspoon.’! It
would indeed be unreasonable thus to denote
the differences between those objects, although
their agreement may be quite properly expressed
by the single phrase ‘ forms of silver’. ‘ Variation,’
too, may be reasonably used in a generic sense to
cover many widely different departures from what
is regarded as the normal form of a species. But,
to make use of Professor Bateson’s metaphor,
we are now threatened with the sort of confusion
that would arise if (1) A declared that the word
‘teaspoon’ meant a teaspoon, and (2) B and C
spread broadcast the statement that A had really
applied this term not to a teaspoon at all, but to
a shilling.
It is probable that Professor Bateson’s and
Mr. Punnett’s error arose when they became
aware that de Vries attributed ‘fluctuations’ to
nutrition, using this term in a broad sense. They
do not appear to have realized that, whereas
regression rendered evident through heredity is
the essential element in de Vries’s ‘fluctuations’,
the opinion that they are acquired is quite
unessential. De Vries, in fact, treats the trans-
? Report Brit. Assoc., Cambr. (1904), 576.
262 APPENDIX D
mission of acquired characters with a levity justly
rebuked by Mr. R. H. Lock in the following
passage :— .
‘
. . . de Vries believes that individual variability de-
pends entirely upon nutrition; but under this head he
includes practically the whole environment of plants—
light, space, soil, moisture, and the like. Characters ac-
quired ina similar way by previous generations are inherited,
and the effect of conditions upon the developing seed whilst
still borne upon the parent plant may be considerable.
Thus easily does de Vries dispose of the puzzling question
of the inheritance or non-inheritance of acquired characters.
Acquired characters are inherited; they are not of any
importance in the origin of species.’?
It will now be well to show from several
passages that de Vries considers ‘ fluctuations’ to
be hereditary, and that the limits which he
assigns to them only become manifest by means
of heredity.
‘|. . we must,’ says Mr. Punnett, ‘ recognise
with de Vries the type of variation which he_has
termed fluctuating? In order to ensure an
accurate recognition it will be safest to quote
de Vries’s words. .
(1) In the celebrated Mutationstheorie (Leipzig,
1901, I.) de Vries states that, in advocating the
use of the term ‘ fluctuation’, he is merely adopt-
ing a word often used by Darwin himself." Thus,
1 Variation, Heredity and Evolution, London, 1909, 2nd Ed.,
155. - See also passage (1) quoted from Mr. Lock on p. 270.
2 Mendelism, R. C. Punnett, 2nd Ed., Cambr. (1907), 70.
3 An example of Darwin's use of the words ‘fluctuating variability’
is to be found in the following passage from a deeply interesting
- — a
“> =
DE VRIES ON ‘FLUCTUATIONS’ 268
speaking of ‘individual variability’, he says on
pages 86 and 37: ‘This [form of] variability has
been termed, fluctuating, gradual, continued, rever-
sible, limited, statistical, and individual. The latter
designation appears to be most widely spread in
the domain of zoology and anthropology, whilst
the term fluctuating or flowing which was
frequently used by Darwin, ought certainly to be
the best.’ That regression, only evident through
heredity, is characteristic of fluctuations, is stated
on p. 88: ‘Individual variability is, by propaga-
tion [literally by sowing], revertent into itself.’
Again, on pages 38 and 39 :—
‘ Auf dem Gebiete der individuellen Variabilitait fihrt die
Selection zu der Entstehung der Rassen. Dabei ist aber, wie
wir bereits gesehen haben, dieses letztere Wort in einem
anderen Sinne gebriiuchlich, als in der Anthropologie.’
Die principielle Differenz dieser sogenannten veredelten
Rasse einerseits mit Varietiiten, Unterarten, elementaren
letter, criticizing the hypothesis of the direct influence ot environ-
ment as a motive cause of evolution :—
‘In ‘regard to thorns and spines I suppose that stunted and
[illegible] hardened processes were primarily left by the abortion
of various appendages, but I must believe that their extreme
sharpness an ness is the result of fluctuating variability and
the “ survival of the fittest.’ In a letter to G. H. Lewes, Aug. 7,
1868. More Letters, i. 308.
* De Vries is here referring to p. 29, where he distinguishes the
two kinds of races as follows. It will be seen that the hereditary
transmission of fluctuations selected by the breeder is even more
clearly expressed than in the passage quoted in the text:—
*‘ Aber das Wort Rassen hat bekanntlich eine doppelte Bedeutung.
Es bedeutet sowohl die durch Selection veredelten Rassen unserer
Ziichter, als auch die vorhandenen, constanten Unterarten unbe-
kannter Abstammung.’
{‘ But the word races has, as we all know, a double meaning. It
signifies races improved by the selection of our breeders as well as
existing, constant sub-species of unknown origin.’]
264 APPENDIX D
Arten, incipient species u. 8s. w. andererseits, soll den
Gegenstand unseres dritten Kapitels bilden.’
[‘ Within the domain of individual variability selection
leads to the origin of races, but, in considering this question,
as we have already seen, this latter word [races] is used in
a different sense to that employed in Anthropology. The
essential characteristics of this so-called improved race, on
the one hand, and of, on the other hand, varieties, sub-
species, elementary species, incipient species, &c., &c., will
constitute the subject-matter of my third chapter.’ |
I would ask how it is possible for races to arise
or to be improved by the selection of individual
variations (or fluctuations) if it be supposed that
those latter are non-transmissible by heredity.
The German of the latter part of the passage
quoted on pp. 263-4 is not very clearly expressed.
My friends who are experienced in the rendering
of German into English have generally found
themselves puzzled by it, at any rate on a first
reading. Professor A. A. Macdonell tells me
that the obscurity is due to the use of ‘mit’ for
‘und der’, At the same time he is sure that the
‘einerseits ’ and ‘andererseits’ express a ‘contrast
which is unintentionally softened down by the
use of ‘mit’. This conclusion, based on purely
linguistic grounds, is confirmed by a consideration
of the subject-matter; for every student of de
Vries knows that all the forms in the category
beginning ‘ Varietiiten’ are explained by him as
‘mutations’, and are as a matter of fact in many
parts of his works sharply contrasted with the
products derived by selection from ‘ fluctuations’.
-
—_e
DE VRIES ON ‘FLUCTUATIONS’ 265
I have considered these passages in some
detail because Dr. Shipley informs me that the
interpretation of de Vries’s ‘ fluctuations’ as non-
transmissible by heredity is based upon this
portion of the first volume of the Mutationstheorve.
(2) Speaking of the means by which the in-
dividual steps of evolution are brought about,
de Vries says :—
‘On this point Darwin has recognized two possibilities.
One means of change lies in the sudden and spontaneous
production of new forms from the old stock. The other
method is the gradual accumulation of those always present
and ever fluctuating variations which are indicated by the
common assertion that no two individuals of a given race
are exactly alike. The first changes are what we now call
“mutations”, the second are designated as ‘individual
variations ”, or as this term is often used in another sense,
as “fluctuations”. Darwin recognized both lines of evo-
lution ; Wallace disregarded the sudden changes and pro-
posed fluctuations as the exclusive factor.’ '
It has been abundantly shown in the present
volume (pp. 43, 44, 254-6) that de Vries is wholly
mistaken in ascribing to Darwin a belief in
evolution by mutation, and in maintaining that
there was in this respect any difference between
the two discoverers of Natural Selection. It is
amusing to observe the reason given by de Vries
for preferring the term ‘fluctuation’, May we
hope that he will abandon the word now that it
too ‘is often used in another sense’?
P Hoge | e Vries, Species and Varieties: their Origin by Mutation.
Second Ed., Chicago and London (1906), 7, 8.
266 APPENDIX D
Fluctuations are, according to de Vries, unable,
however rigidly and however long selected, to
lead to progressive evolution. The following
passages in which this belief is expressed, assert
perfectly clearly that these limitations—rashly
assumed to be permanent—are revealed by means
of heredity. They also plainly show that de
Vries, in maintaining the uselessness of ‘ fluctua-
tions’ as the material for progressive evolution, is
merely availing himself of a principle established
much earlier and on far firmer grounds by
Francis Galton—the well-known principle of
‘recession towards mediocrity ’ :—
(3) ‘Fluctuations always oscillate round an average, and
if removed from this for some time, they show a tendency
to return to it. This tendency, called retrogression, has
never been observed to fail, as it should, in order to free the
new strain from the links with the average, while new
species and new varieties are seen to be quite free from
their ancestors and not linked to them by intermediates.’ !
In the following passage, as well as in (5),
de Vries is of course referring to ‘ fluctuations’ :—
(4) ‘. . . Long-continued selection has absolutely no
appreciable effect. Of course I do not deny the splendid
results of selection during the first few years, nor the
necessity of continued selection to keep the improved races
to the height of their ameliorated qualities. I only wish
to state that the work of selection here finds its limit and
that centuries and perhaps geologic periods of continued
effort in the same direction are not capable of adding any-
thing more to the initial effect.’ *
1 Species and Varieties, 18. >. 2. 9 Kbid.5 790-1.
ret
DE VRIES ON ‘FLUCTUATIONS’ 267
After reading the impetuous conclusions ex-
pressed at the end of the last-quoted passage, it is
refreshing to turn to Darwin’s calm and convinc-
ing statement in the letter quoted on p. 48.
(5) ‘Even sugar-beets, the oldest “ selected ” agricultural
plants. are far from having freed themselves from the
necessity of continuous improvement. Without this they
would not remain constant, but would retrograde with
great rapidity.’’
It will now be of interest to inquire howde Vries’s
‘ fluctuations ’ have been understood by others, and
especially by his friend and fellow countryman,
Professor A. A. W. Hubrecht, the distinguished
zoologist. A few years ago Professor Hubrecht
wrote an account of de Vries’s contributions to
evolutionary thought in the Popular Science
Monthly.2, The editor has added the following
note to the article (p. 205): ‘This article was
written in English by Professor Hubrecht, the
eminent Dutch zoologist, who has an equal com-
mand of the French and German languages.’
Every one who has the privilege of the friendship
of Professor Hubrecht and knows of his great
linguistic powers will agree that probably no
other man is so qualified to express de Vries’s
precise meaning in the English language. I
select seven passages from the article in question.
All of them would be meaningless if ‘ fluctuations’
are supposed to be non-transmissible by heredity.
. cies and Varieties, 109.
* For July, 1904 ; 205-23, ‘Hugo de Vries’s Theory of Mutations,’
268 APPENDIX D
(1) ‘The different degrees of fluctuating variability can
undoubtedly be seized upon by any one who wishes to make
them the starting-point for the breeding of certain distinct
variations. Thus, for instance, by constantly selecting for
the reproductive process those plants in which a given
deviation is strongly marked, after a certain time and after
a series of generations, a plant can be obtained for which the
Galton curve would indicate a displacement of its culminating
point in the direction of the selected variation. In this way an
increase in the yield of sugar obtained from the beet roots
has been arrived at from about 7 per cent. to 13 or 14 per
cent. Thus also ears of maize have been produced that
bore 20 rows of grain, whereas the kind from which the
experiment had started always bore 12 to 14 rows.
‘ As soon, however, as such conscious and voluntary selec-
tion ceases, the next generations successively return to the
original curve.’ (p. 209.)
(2) ‘. . . breeding variations to the right or to the left
of the norm, can never exceed certain limits. Agencies are
at work there which prevent the fluctuating variability
from going any further. The existence of such limits
compels us to acknowledge that there is no possibility that
species might arise in nature according to the same plan
by which certain breeds originate under artificial selection.’
(pp. 209-10).
(3) ‘We have seen that fluctuating variability leads to
slow changes and furnishes farmers with the material to
improve the races of animals and plants.’ (p. 210.)
(4) ‘. . . by means of fluctuating variability certain local
and improved races may indeed be bred, but that in nature
new species never arise through its agency.’ (p. 210.)
(5) ‘As long as the mutation has not appeared, there can
be no question of the origin of a new species ; the species is
then constant, and only submitted to fluctuating variability,
which can produce local races (not elementary species) under
the constant cooperation (either artificial or natural) of
selection, but which never leads to the formation of species.’
(p. 216.)
(6) ‘The elementary species are stable. Selection calls
HUBRECHT ON ‘FLUCTUATIONS’ 269
forth different races within the limits of. these species, but
whenever selection ceases the race is turned back to the
parent form. The maximum deviation in these races is
generally obtained after three or four generations of con-
tinuous selection; it takes about as many generations to
bring back the parent form.’ (p. 219.)
(7) ‘The fact that artificial selection of fluctuating varieties,
as well as hybridizing, etc., has already led to such indis-
putable improvements in the different races of animals and
plants may, however, etc.’ (p. 223.)
Finally in an article only published about a
year ago in the Contemporary Review! Professor
Hubrecht says :—
‘Wherever our agriculturist succeeds by the most
careful artificial selection in producing (e. g.) a beetroot of
which the percentage of sugar has been raised, say, to 15 per
cent. out of roots which originally stood at 7 to 8 per cent.,
he knows that the fluctuating variation of the beetroot has
permitted him to attain this end; but he knows, at the
same time, that what he has obtained is not a new species
of beetroot, richer in sugar, but a product of nature which
the moment it is left to itself and freed from the bonds of
artificial selection goes back to an inferior sugar-producing
root again,’ (p. 633.)
I will now prove, although more briefly, that
other writers have understood de Vries cor-
rectly. The sectional heading employed by
Professor C. B. Davenport—‘ Mutation vs. Sum-
MATION OF FLUctuATIONS’ *—is sufficient to show
this ; for summation would be impossible without
hereditary transmission. We do not, however,
1 For Nov., 1908, ‘ Darwinism versus Wallaceism."
2 Fifty Years of Darwinism, New York (1909), 173.
270 APPENDIX D
need to base our proofs upon inference, for Prof.
Davenport makes the following clear statement :—
‘Does the breeder actually introduce new characters into
the organic world by summating fluctuations? De Vries
insists that the improvement that follows selection nearly
or wholly ceases after four or five generations, and if selection
be abandoned the race rapidly returns to its primitive
condition.’?
The two following passages are quoted from
Mr. R. H. Lock’s book ? :—
(1) ‘There are some, including de Vries, who regard all
fluctuating variations (individual differences) as being of the
nature of acquired characters, and as being at the same time
capable of hereditary transmission, although de Vries
believes the amount of progress possible in this way to be
strictly limited.’ (p. 75; see also the passage Tee from
Mr. Lock on p. 262.)
(2) ‘The actual effect of this kind of selection is well
illustrated by the results of the processes employed in the
sugar-beet industry, in which elaborate care is taken to
select those roots which contain the highest percentage of
sugar for the purpose of propagation. This process was
followed at first by a rapid improvement, but the rate at
which the percentage of sugar increased soon fell off, until
at the present day all that selection can effect is to more up
the standard of excellence already attained.
* * *
‘There is no reason to doubt that a thoroughly efficient
method of selection would have worked its full effect in
a few generations.
* * x
‘From his own experiments, de Vries has come to the
conclusion that, when selection is really efficient, the full
possible effect of this process is exhausted in quite a small
1 Fifty Years of Darwinism, New York (1909), 173-4.
2 Variation, Heredity and Evolution. London, 1909. Second Ed.
OTHER WRITERS ON ‘FLUCTUATIONS’ 271
number of generations, and that then the only further effect
of selection is to keep up the standard already arrived at.’
(pp-. 185-6.)
e Professor J. Arthur Thomson! in the first of
the following passages clearly states the germinal
origin of fluctuations, in the second correctly
expresses de Vries’s conclusions :—
(1) ‘. .. when we collect a large number of specimens of
the same age from the same place at the same time, we
often find that no two are exactly alike. They have peculi-
arities of germinal origin—or, in other words, they show
individual or fluctuating variations.’ (p. 78.)
(2) ‘Fluctuations do not lead to a permanent change in
the mean of the species unless there be a very rigorous
selection, and even then, if the selection be slackened, there
is regression to the old mean: mutations lead per saltum to
a new specific position, and there is no regression to the old
mean. (p. 98.)
I have brought perhaps unnecessarily ample
evidence in support of the fact that de Vries’s
‘fluctuations’ are assumed by him to be trans-
missible by heredity, and that this assumption is
an essential element in the author’s definition of
his technical term. When we remember that
they are just the ‘individual differences’ of
Darwin, and that de Vries’s belief in their power-
lessness for continued evolution is based on Francis
Galton’s well-known law of recession, it is really
waste of time to inquire whether they are trans-
missible. But such positive statements to the
contrary have been made by the most prominent
1 Heredity, London, 1908.
272 APPENDIX D
supporter of de Vries in this country—statements
accepted and widely circulated by others—that it
appeared expedient to produce even redundant
proof that the Dutch botanist has been uninten-
tionally but fundamentally misrepresented in a
matter of supreme importance.
In conclusion I think it may be convenient to
sum up briefly a few opinions that have been
expressed during the past fifty years as to the
variations which form the steps of evolutionary
progress. Such a short statement, which I will
endeavour to express as clearly as possible, may
do something to bring within reasonable limits
those unduly exaggerated estimates of recent
achievement which tend in the long run to
diminish rather than to exalt the fame of an
investigator. .
CHarLEs Darwin. It has been shown on
many pages of this book that Darwin recognized
large variations transitional into individual dif-
Jerences, but that, with A. R. Wallace, he
believed the onward steps of evolution were
supplied by the latter and not by the former.'
He admitted that advance might be arrested by
? The following passage is quoted from p. 45 of the Ist Edition
of the Origin :—‘ Again, we have many slight differences which may
be called individual differences, such as are known frequently to
appear in the offspring from the same parents, or which may be
presumed to have thus arisen,...’ ‘These individual differences
are highly important for us, as they afford materials for natural
selection to accumulate, in the same manner as man can ac-
cumulate in any given direction individual differences in his
domesticated productions.’
DARWIN ON EVOLUTION 278
the limits of variation, but did not believe that
_the limits were necessarily permanent. He held
that the appearance of variations was an indirect
response to the conditions of life, their character
being determined by internal causes and not by
the nature of the external stimulus.
It is generally assumed that Darwin did not
consider the question of the hereditary trans-
mission of acquired characters. Professor Meldola
has, however, pointed out to me the following
interesting passage which has appeared, with only
the slightest verbal change, in all editions of the
Origin :—
‘Some authors use the term “variation” in a technical
sense, as implying a modification directly due to the
physical conditions of life; and “‘ variations” in this sense
are supposed not to be inherited: but who can say that
the dwarfed condition of shells in the brackish waters of
the Baltic, or dwarfed plants on Alpine summits, or the
thicker fur of an animal from far northwards, would not in
some cases be inherited for at least some few generations ?
and in this case I presume that the form would be called
a variety ’ (lst Ed., 44, 45).
Mr. Francis Darwin can throw no light upon
the ‘authors’ referred to. It is deeply interesting
to observe that Darwin did not, even in 1844,
believe in the inheritance of the effects of
mutilation or of mechanical pressure.'
Francis Gatton investigated the hereditary
transmission of individual differences and proved
» The Foundations of the Origin of Species, Cambridge (1909),
T
274 APPENDIX D
that many are subject to the law of ‘ recession
towards mediocrity’. He considered that evolu-
tion proceeds by the selection of large variations
(saltation) as well as of small. He suggested
that certain variations do not obey the law of
recession, but are the expression of a sudden leap
to a new position of genetic stability. He thus
anticipated de Vries in both ‘ Fluctuations’ and
‘Mutations’, proposing for the latter type of
variation the far better and far more descriptive
term ‘ transilient’.
The conclusion that evolution has been ‘ dis-
continuous’, proceeding by means of relatively
large steps, was urged with much vigour by
Professor Bateson in his work On Variation (1894).
It was in a review of this book that Galton pro-
posed the term ‘transilient’, although the opinion
that evolution may take place by large steps
had been expressed by him at a much earlier
date.
Avuecust WeIsMANN revealed the unsubstantial
nature of the evidence on which the hereditary
transmission of acquired characters ! was believed.
1 It may be convenient to quote three passages from the author's
Essays on Evolution (1908) :—
(1) ‘For the question ‘Are acquired characters hereditary ?’
it would be more accurate to substitute ‘Can the acquired char-
acters of the parent be handed down as inherent characters in the
offspring ?’’ (p. 144).
(2) ‘ It isinno way ahaevery’E that the acquired elements of a char-
acter should be disentangled from the inherent elements, if only we
can prove that the character as a whole is dependent upon a con-
trollable external cause, and is therefore itself controllable. In
fact we speak of a character as ‘acquired ' just as we speak of an
article as ‘manufactured’, although the result itself is a complex
GALTON AND WEISMANN 275
His teachings have led to the general, but not
the universal, abandonment of the Lamarckian
element in evolution as Darwin conceived of
it, They receive support from the numerous
Mendelian and Mutationist researches which
lead to the conviction that variation is essentially
of germinal origin.
Weismann’s conceptions of evolution are as
much affected by the facts of adaptation as were
those of Darwin himself, and he is equally con-
vinced that the onward progress of evolution has
been by small steps and not by large ones.
In speaking of ‘acquired characters’ it may
not be out of place to point out that every
character contains acquired elements, because en-
vironmental influence of some kind is necessary
for the existence of all characters. When the
differences between corresponding characters in
different individuals can be traced to environmental
influences the characters are called acquired, when
they can be traced to germinal influence they are
called inherent. ‘Environmental influence’ is
here used in the broadest sense and includes the
other parts of the same organism. Thus the use
or disuse of a part, when determined by the
brain, is no less an acquired character than when
it is imposed by the conditions of the external
world.
of the properties of natural substances and of changes introduced
by art’ (p. 144).
(3) ‘ Whenever change in the environment regularly produces
appreciable change in an o ism, such difference may be called
an acquired character ' (p. 143).
T2
276 APPENDIX D
Hueco pe Vrrss considered himself led by his
work on the Evening Primroses and by confirm-
ing Galton’s law of ‘recession towards medio-
crity ’, to the conclusion that evolution proceeds
by Mutation or Transilience alone, and that
individual differences, called by him ‘fluctua-
tions’, do not lead to marked or permanent
change. He does not hesitate to conclude that
‘fluctuations’ are both hereditary and acquired,
and that evolution proceeds by the intermittent
explosive discharge of an internal transforming
force. According to de Vries, the réle of Natural
Selection is to determine the survival of the fittest
among the Mutations scattered in all directions
by species during their explosive periods.
Grecor Menpet. The thoughts of this wonder-
ful man should follow those of Darwin, but his
great discoveries were so long lost to the world,
that their final recognition has produced the most
recent of all the phases of evolutionary thought.
We are led by Mendel’s researches, which it is
unnecessary to describe, to the conception of ‘ unit
characters ’ :—
‘By a unit character in the sense of Mendel’s law, we
mean any quality or part of an organism, or assemblage of
qualities or parts, which can be shown to be transmitted in
heredity as a whole and independently of other qualities
or parts.’?
We are also led to the conclusion that a unit
character is represented in the germ-cell by a
1 W. E. Castle, in Fifty Years of Darwinism (1909), 146.
DE VRIES AND MENDEL 277
determinant (which may consist of one or several
factors) or by many linked determinants. For
those who hold that the transformation of species
proceeds not by the modification but by the
addition of new or the subtraction of old unit
characters (in the above sense) these conclusions,
founded on Mendelian research, are of supreme
importance in evolution. Professor Bateson has
recently prophesied :—
‘,.. We see Variation shaping itself as a definite, physio-
logical event, the addition or omission of one or more definite
elements; and Reversion as that particular addition or
subtraction which brings the total of the elements back to
something it had been before in the history of the race.’}
To those who believe that the outcome of
Mendelian research does not bring any essential
change in the conception of evolution received
from Darwin, the results are still of supreme
interest and importance. Just as the splendid
cytological work of the past half century helps
us to form a picture of the mechanism of fertiliza-
tion and of heredity but does not alter our con-
ceptions of evolution, so is it with Mendelian
research. Upon fertilization and heredity it sheds
an even stronger, surer light than that thrown
by cytology. We are enabled to understand by
the help of examples which obey Mendel’s law
something of the general, perhaps the universal,
mechanism of heredity. This performance and
the promise of deeper knowledge in the future
1 The Methods and Scope of Genetics, Cambridge (1908), 48.
278 . APPENDIX D
are enough to stamp Mendel’s discovery as among
the greatest in the history of the biological sciences,
But it does not alter the Darwin-Wallace concep-
tion of evolution in nature.
The pattern of each mimetic form of the poly-
morphic female of Papilio dardanus is a complex
unit character as defined by Castle, yet all of
them exhibit clear evidence of a past history of
‘continuous’ improvement in the likeness to
their respective models. |
Sports such as those which arise by the dropping
out of some definite element and the consequent
sudden change to white of the whole or a part
of the pigment of an animal or flower, are a type
of the appearances which are attractive and
interesting to man, and have become subject
to artificial selection. And it is with material
thus derived that nearly the whole of Mendelian
research has been hitherto concerned. Selection
may occasionally operate along similar lines in
nature, as when an animal migrates into some
snow-covered area, but no one who has ‘reflected
much upon the struggle for existence can believe
that it is the usual method of evolution.
Similarly with regard to the limited advance
that is possible when fluctuating variability is
artificially selected. Man is able, in a few genera-
tions, to double the percentage of sugar produced
by the beet. By selecting for this quality alone,
he profoundly modifies the relationship of one
particular function to the plant as a whole, and
ARTIFICIAL vy. NATURAL SELECTION 279
after a time finds that, within the limited
period of his endeavour, he can go no further.
But Natural Selection does not operate in this
way upon single qualities. Every quality of direct
or indirect value to the organism and at the same
time the inter-relationships of all qualities, are
selected simultaneously. Artificial selection does
not give us a true picture of the method of nature.
Darwin, as I have said, held that the steps
of evolution were built out of small individual
differences. He did not doubt that these could
be accumulated by selection, but he was prepared
to believe that there would be halts. I have
always foreseen that the Mutationist would finally
‘hedge’ by claiming as mutations the minute
differences on which Darwin relied.! This
tendency is very clearly seen in Mr, Punnett’s
little book ? :—
‘Doubtless some of the so-called fluctuations are in reality
small mutations, whilst others are due to environmental
influence’ (p. 72).
‘A cursory examination of horticultural literature must
convince anyone, that it is by selection of mutations, often
very small, that the gardener improves his varieties.
Evolution takes place through the action of selection on
these mutations’ (p. 74).
As the Mutationist comes to study the details
of adaptation, and as further fossil records pre-
served under peculiarly favourable conditions are
? Essays on Evolution, xxxviii, xxxix.
2 Mendelism,
280 APPENDIX D
carefully examined,! we may feel confident that
the belief in an evolution founded on large
mutations will vanish, and we shall then come
back to mutations identical in every respect with
the small variations which were for Darwin the
steps of evolution.
A humorist has suggested that the Homer
controversy should be settled by a general agree-
ment that the Jliad was written not by Homer
but by another man with the same name. Those
who have heralded with such a flourish of trum-
pets the profound changes which they assume
to be necessary in the Darwinian conception of
evolution, may yet ‘save their face’ by calling
the same thing by another name.
1 Dr. Arthur W. Rowe's researches on the fossils of the white
chalk are an admirable example. See the Quarterly Review (July,
1909), 19, 20.
INDEX
The words ‘ Darwin to’ refer to letters from Charles Darwin
quoted in this work.
Abraxas grossulariata, taste of,
242 n. 1.
Achaea chamaeleon piercing
peaches, 224 n. 1.
Acquired characters, early uses
of terms, 3n.2; Beccari on, 20;
Lamarckism and, 33-42; ‘ fluc-
tuations’ and,49n.1; Darwin
on the transmission of, 273;
de Vries do., 261-2, 270, 276;
Poulton do., 274 n. 1; Weis-
mann do., 274-5.
Acraea, 239,
johnstoni, 130.
Acraeinae, as models, 152-3,
178-9; as possible mimics,
154 n. 1,
‘Acraeoid Heliconidae’, of
Bates, 153.
= memory and, 40;
teleology and, 94-8; natural
selection and, 98-101; muta-
tion and, 279.
Adelpha,mimicked in 8. America
by Chlorippe, &c., 176; in N.
and Central America by Li-
menitis, 192-3, 197, 207-8,
208 n. 1; — lerna, 192; —
dyonysa, 192 ; — fessonia, 192;
— massilia, 192.
Aden, 157.
een aceey ce Tmermncephoges,
Africa, 157; thorn-bearing
plants in, 98; butterfly models
- in, a4 ; mimicry x 161.
iz, A., support to Darwin
Agassiz, L., opposed to Darwin,
28, 54-5 ; Barats to, 68-9.
Albany, N.Y., stripeless L. arch-
ippus at, 166 n. 2, 211-12.
albens, Physianthus, 225, 225 n.1.
albinism, 251.
Aleutian Islands, 162.
Alpine forms often arctic, 45, 123,
123 n. 2; — plants dwarfed,
273. ;
Alydus, mimicking ants, 116.
Amazons, 126.
America: see also ‘N. America’
and ‘8. America’; evolution
in, 1-3; palaeontology in, 2-3;
probably uninhabited by early
man, 35 ». 2; Pharmacopha-
gus in, 177-81.
American Assoc. Adv. Sci., viii,
1, 48, 57, 154, 156; Darwin
Centenary of the, vili, 1, 57.
American Naturalist, 142.
americus, subsp. of Pap. poly-
wenes, 184.
Amphidesmus analis, mimick-
ing a Lycid beetle, 121-2.
ampliata, f. of Pap. asterius, 182.
Anacampseros papyracea, re-
semblance to dung of birds,
102 n. 2.
Ancestral forms, preservation
of, 46-7.
aa asa group of ‘ Papilio’,
2.
Animals and Plants under Do-
mestication, C. Darwin, 68.
— and Mag. Nat. Hist:, 229
ao
282
—— of Botany, 97 n. 1, 102
Anosia, see also ‘ Danaida’ ;
154-8, 158 n. 3; a recent
colonist of Fiji, ” Key 155;
— plexippus, 152 n. 1, 154,
158-9, 158 n. 3, 161-4, 168-
73, 177, 204-5 ; a foreign ele-
ment in N. World, 204.
Ansted, D. T., Darwin to, 131.
Antagonism falsely assumed be-
tween science and literature,
79-83.
par i Pharm., of Madagascar,
77.
Ants, as models for mimicry,
115-18.
Apatura, mimicking Limenitis,
175-6.
Apocyneae, 217; capturing Di-
ptera, 225.
Aposematic colours, 110-12.
Araschnia levana, mimicking
Limenitis, 176.
Archaeopteryx, discussed at Brit.
Assoc. (1881), 29, 30.
archippus, Limenitis, 137, 155,
161, 164-72, 176, 186-8, 191,
199, 204-5; evolution of
mimicry in, 164-8 ; stripeless
var, at Albany, 166 n. 2,
211-12.
arctic alpine forms, 123, 123
n. 2.
Arctiidae, as mimics, 121.
Argyll, Duke of, on natural
selection, 44; criticisms by,
251-3 ; Darwin to, 251-2.
Argynnis diana, female of
mimics, LD. astya-
nax, 189, 207.
niphe, female of
mimics, D, chrysip-
pus, 161,
arietis, Clytus, 115.
Aristolochia and allies,
plants of Pharma hhagus,177.
‘Aristolochia _ swallow - tails’
(Pharmacophagus), as models,
137, 177-81, 206-7.
Aristotle, 83.
food-
INDEX
Arizona, 176, 192-3, 205, 208.
ae 8., on origin ‘of life,
arthemis, Limenitis, 137, 164-6,
172, 176, 186-8, 196, 204-5,
207 ; the ancestor of L. arch-
ippus, 164-8, 204-5; and of
L. astyanax, 186-8, 205, 207.
artificial versus natural selec-
tion, 278-9.
Asclepiadae, food-plant of Dan-
ainae, 162; insects and pol-
len-masses of, 217, 225-6, 225
Ashmolean Museum, Oxford,
95-6.
‘assembling’ of males of ‘Oak °
Eggar’ moth, 230 x. 2, 235,
28 n. 1, 24, 242 n1.
asterius, subsp. of Papilio -
xenes, 182-5, 188, 206. -"
astyanax, Limenitis, 172, 186-91,
199, 205, 207.
asyllus, Euploea, mimicked by
a Danaida (Salatura), 160,
Athenaeum, 15.
Atlantic States, 186,
Atolls, 45.
Attidae, mimicking ants, 116-17.
Australia, 155 ; insects captured
by Darwin in, 202-8.
‘ Autobiography of Charles Dar-
‘win’, 51, 58 mn. 2, 59, 60, 63-4,
66, 74-6, 75 2, 85 n. 1, 99
n. 1, 100, 108, 123 n, 2, 140.
Avebury, Lord, on’ Darwin’s
gardener, 71; Darwin to, 203,
Bakewell ,shorthorn cattle made
by, 492.
Baldwin, J. M., on organic selec-
tion, 3, 48; on Psychology
and "natural selection, 3; on
ip of social environment,
Balfour, A. J., speech at Cam-
bridge centenary by, 84.
Baltic shells dwarfed, 273.
barbata, Disa, 220 n.1.
Barber, Mrs. M. E., on P. nireus
pupae, 109.
Basilarchia, a subgenus of
Limenitis, q. v.
Batchian,
Bates, H. W., 46, 101, 112, 116,
118-19, 149, 151, 158, 174-7,
189, 191, 225, 227-8, 228 n. 1,
35; theories of F. Miiller
and, 114-32; Lycid mimicry
and theory of, 118-21; me-
moir on mimicry by, 122-6,
236, 238-9, 240; inscription
in Wallace's copy of, 123;
theory of, anticipated by Dar-
win, 46, 123-4; reviewed by
Darwin, 125-6; theory
thought out at home by, 126;
two classes of resemblance
distinguished by, 126 ; Miiller
dissatisfied with theory of,
127-8; Miiller’s theory op-
posed by, 129; Batesian
mimicry defined, 149; Dar-
win’s interest in, 123-6, 144-
5; protective resemblance
and Retesian mimicry, 101,
146-7, 174-5; female of Arg.
diana probable example of
Batesian mimicry, 190-1, 207;
N, American mimicry as a
whole opposed to theory of,
174-7, 205, 207; Darwin to,
123-6, 141.
Bateson, W., on de Vries’s
‘fluctuations’, xi, 259-61;
on an effect of the Origin,
52; on discontinuity in
evolution, 274; on causes
of variation and reversion,
277.
ey voyage of the, 1, 4-6, 60,
66 n. 2, » 108, 202, 208
n. 1, 214.
Beccari, views on evolution of,
19, 20,
bee, igre with Orchid
and, 225.
Beebe, C. W., on moisture and
bird colours, 110; on con-
trol of birds’ nuptial plumage,
142-3; natural selection and
experiments of, 143, 29
INDEX 288
beech light and shade foliage
of, 41-2,
beet, selection of ‘ fluctuations’
in, 267-70, 278-9.
Belt, T., on Nicaraguan frog
111; on sexual selection and
mimicry, 135.
Bentham, G., 13-14, 253 ; effect
of joint essay and Origin on,
13 n. 2; Darwin to, 253.
berenice, Danaida (Tasitia), 154,
157-8, 162-3, 168-72, 204-5.
Beuttler, J. S., on colour adjust-
ment of chameleon, 109.
birds, Beebe’s experiments on,
110, 142-8; fertilization of
Strelitzia and, 217, 228-9, 228
n. 2; light attractive to, 243.
Blanchard, E., on an unknown
sense in insects, 235 mn. 1, 242,
242 n. 1,
Blomefield, L., see ‘Jenyns’.
Blyth, E., 241,
bobolink, 142.
Bonatea, Darwin and Trimen on,
217-18, 220, 228-9, 229 n. 1.
Borneo, 19.
Bourne, G. C., 78.
Bourne, R., 79.
Boys, 6. V., on colour adjust-
ment of chameleon, 109.
Braconidae, as models and
mimics, 120.
Bradley, Andrew, on imagina-
tion, 62.
Brazil, 8. E., F. Miiller’s theories
of mimicry worked out in,
126-8.
bredowi, Limenitis, 192-3, 197-8,
207-8.
brenchleyi, Euploea, 160.
British and South African Associ-
ations, Report of the, 96 n. 2.
British Assoc. Adv. Sci., Meet-
ings and Reports of the, 17,
29, 30, 38, 49 m. 1, 50 nm. 1, 52,
54-5, 66-9, 89, 258-9, 261.
British Columbia, 193.
Brooks, W. K., 108.
broom, 202.
Brown, R., death of, and publi-
284
cation of the joint essay, 12-
14; on Asclepiadae, 225-6.
Brownleia, 220 n. 2.
Brunton, Sir Lauder, Darwin to,
3
Buckland, Dr., influence of, on
Lyell and indirectly on Dar-
win, 7, 86, 95.
Buffalo Soc. N. Sc. Bull., 192.
oer xili, 15, 28.
(Hemi tera), as mimics,
Ti6-18, 120,
Burchell, F. A., manuscripts of
aa . Burchell discovered by,
102.
Burchell, W. J., 93; present at
reading of joint essay, 18;
detachment of, 27; on the
sublime, 36-7; on adaptation,
96-9; on cryptic resemblance
to stones, 96-8, 102-3; on
defences of desert plants, 98;
examples of mimicry observed
by, 114-22.
Butler A.G., on distastefulness
of conspicuous larvae, 112.
Butterflies, mimicry in, 128,130,
132-9; scents of, 141-2:
ay in N. American, 144-
212.
Butterflies of the Eastern United
States and Canada, Scudder,
152 n. 1,165; see also ‘ Scud-
der’.
Butterfly Book, Holland, 171,
211; see also ‘ Holland’.
Byron, 77.
californica, Limenitis (Adelpha),
191-200, 207-8.
Cambridge, Darwin and Uni-
versity of, 84-91, 203; Darwin
celebrations at, ix, 79.
Canada, 176, 185, 194.
canadensis, "subsp. of Papilio
glaucus, 182,
Cantharidae, as mimics, 120.
Cape and Cape Town, 156, 213,
20 n. 1 and n. 2, 221-2, 228,
228 nm. 1, 246.
Cape de Verde Islands, 6, 108.
INDEX
Cape pe aay Magazine, 245
Carabi, of Beagle, 202. :
Carlyle, Mrs., on R. Owen, 27
Carpenter, W. B., present at
reading of joint essay, 13.
Carus, Victor, 255.
Castle, W. E., on ‘unit char-
acters’, 276, "278.
Catalogue of the Ashmolean
Museum, J. 8. Duncan (in
work of P. B. barn 95-6.
Caterpillars, warning colours of,
111, 112.
Catskill Mountains, 211.
Centres of creation, 248-9.
ee mimicry in, 138, 136,
6
Ceylon, 157.
Chalk, continuous evolution in
the ‘white, 280 n: 1,
Challenger, 256.
_ Chambers, R., 15.
chamaeleon, Achaea, 224 n. 1.
Chameleon, W. J. Burchell on,
97; Lloyd Morgan on, 97 ;
colour of, adjustable on two
sides independently, 109, 110.
Charles Darwin and the
of Natural Selection, Poulton,
126, 129,
Chicago, ‘Papilio’ mimics of
philenor taken with their
model at, 185.
nee mimicking Adelpha,
7
chlorophyll, 94.
chrysippus, Danaida, 156-61.
Chrysomela, 202.
Cimex, as mimic, 116-18.
Cinnyris, 228 n. 2.
Clematis glandulosa, 71.
Climbing Plants, C. Darwin, 25.
Clytus arietis, mimicking wasp,
115.
se Pst pamphilus, use of
eye-spots’ of, 231, 232.
Colchester, 235.
Cold Spring Station, 185.
Coleoptera of Beagle, 202.
INDEX
“ae Dr., on mimicry,
Colombia, 184,
Colorado, 176, 180.
Colorado R., Grand Canyon of
the, 37.
Colour, value of, in the struggle
for life, vii, 92-143.
Colours of Animals, Poulton, 115.
‘Coming of Age of the Origin’,
Huxley, 54, 67.
Comptes Rendus, 224 n, 1.
Comstock and Needham, system
of, 211.
Contemporary Review, 32, 269.
continental extension, 246 n. 2;
Darwin opposed to views of
Lyell, &c., on, 45 ; supported
by Dana, 2, 45.
‘continuity of the germ-plasm’,
33, 34; discovery by Weis-
mann of, 39-40.
continuous or discontinuous
evolution, 48-51; mimicry
and, 138-9, 147-8, 200, 208;
fossils of the white chalk and,
280 n. 1.
Cook, J. H., on stripeless L.
archippus, 166 n, 2, 210-12;
lanthanis var. named by
Watson and, 212.
Cope, E. D., American Palae-
ontology and, 2.
Coprid beetles as mimics, 120-1.
Coral islands, Darwin’s theory
of, 75; ite ta by A. Agas-
siz, 2; confirmed, 45.
Cordilleras, 34.
Cornhill Mag., 78.
cornuta, Disa, 220 n. 1.
Cosmodesmus, both sexes of,
mimetic, 137, 179; mimics of |
Pharmacophagus, 137, 177-9 ;
of Danainae, &c., 137, 179.
Coulter, J. M., on oecology and
natural selection, x, xi, 143.
Courtney, Lord, on Shakespeare,
Newton, and Darwin, 77.
Coventry, A. F., 79.
Crassula, mistaken for birds’
dung by Burchell, 102-3.
285
croesus, Ornithoptera, 233 n, 1.
Cross and Self Fertilisation in the
Vegetable Kingdom, C. Darwin,
228 n. 2.
Cryptic colouring, see ‘ Protec-
ive Resemblance’.
curvatus, Neoclytus, 115.
cuttle-fish, variable protective
resemblance of, 108, 109.
Cyllo (Melanitis) leda, Darwin
and Trimen on, 230 n. 2, 233,
288 ». 2.
Cypripedium, Darwin's error in
fertilization of, 224-5, 224n. 2.
Dakota, 170.
— support to Darwin by, 2,
Danaida, four of Moore’s genera
sunk in, 158-9, 204; Old World
affinity of, 160-1; invasion of
N. America from Asia, by way
of N., and of 8. America by
way of N. America, proved
by mimetic relationships of,
155, 159-64, 173-7, 204.
Danaida (Tasitia) berenice, 154,
157-9, 162-3, 168-72,
204-5 ; f. strigosa, 171-
2, cara
(Limnas) chrysippus, 156-
9, 158 ». 3, 160-1.
(Salatura) decipiens, 160 ;
genutia, 158-9, 158 n. 3,
161-2; insolata, 160.
(Anosia) plexippus, 152
n. 1, 154, 158-9, 158
n.3, 161-4, 168-73, 177,
204.
Danainae, as models, 133, 137-8,
178-9, 239; relationship be-
tween New and Old World
species of, 152-9,
| Danaini, a section of the Da-
nainae, q.v., 152; mimicry
between Kuploeini and, 160.
Danais, as models, 239.
‘ <r Heliconidae’ of Bates,
dardanus (merope), Papilio, 182,
139, 236-7, 278.
286
Darwin, Charles Robert, youth,
4; 8. American observations,
1 (see also ‘ Beagle’); Cam-
bridge and, vi, 84-91, 203;
LLD. (1877), 90; Oxford and,
a 86; D.C.L. offered (1870),
Personality of:—vi, 57-77;
absolute necessity for work the
explanation of misinterpreted
changes described in his own
mind, vi, 57-66, 79-83, 216,
256-8 ; relation to his family,
6, 58-9, 87; friends, 4-7, 21-
6, 66-7, 70-1 ; opponents, 26-
30, 28 n. 2, 68-9, 230; readers,
69; younger men, 69-70, 107-
8, 215-17; living things, 72-3.
Intellectual characteristics
of: —love of knowledge, 75-6 ;
powers of observation, 76, 76
n. 3; comprehensive view and
sure insight, v, x, xi, 18, 45-6,
123-4, 123 n, 2, 247-53; ima-
gination and control, 73-5.
On Evolution:—early
thoughts, 1, 4, 5, 53; letter to
his wife on the 1844 essay, 6,
87; urged to publish by Lyell,
12; publication of joint essay,
12-15; onthe steps of evolution
xii-xiv, 49, 49 m. 1, 262 n. 3,
272-3, 272 n. 1; evolution con-
tinuous, 49, 50, 148 ; halts and
fresh starts, 48, 267, 272-3,
279; mutation, xiv, 42-7, 254-
6; multiple origins, 46, 247-
53; causes of variation, 273;
transmission of acquired char-
actersconsidered and accepted
- by, 33-7,273; on heredity and
memory, 38, 38 ». 1; on adap-
tation and natural selection,
98-100, 99 ». 1, 262 n. 3 (see
also ‘orchids’); slight effects
of. climate, 173; effect of
teachings, 52-6, 213-15, 219.
On Sexual Selection :—of
special interest to, 103, 139-
41, 236; yet aware that it was
vulnerable, 141; on Descent
INDEX
of Man, &c., and sexual selec-
tion, 230-6, 242-5; on sexual.
selection and warning colours,
111-12,and markings nowcon-
sidered episematic, 112-18;
and mimicry, 132-5.
On Mimicry, Protective Resem-
blance, &c.:—Bates, Wallace,
Fritz Miller, and Trimen in
relation to, 46, 123-9, 182-5,
144-5, 236, 240-1; on mimetic
Planarians, 122; desert plants,
98; variable colours of octo-
us, 108-9; S. American toad,
10-11; flowers and fruit, 113,
113 ». 3; protective resem-
blance, 103-9; recognition
marks unknown to, 113-13,
Correspondence of : — ex-
tracts from Darwin’s pub-
lished letters to the following
correspondents yi ie on =
quoted pages :—Agassiz, L.,
68-9 ; Kagene. D. T., 18k
Argyll, Duke of, 251-2; Ave-
bury, Lord, 203 ; Bates, H.W.,
123-6, 141; Bentham, G., 2538;
Brunton, Sir Lauder, 73;
Darwin,Erasmus (his brother),
58 .2; Farrer, Lord, 20-1;
Fawcett, H.,16-17 ; Fox, W.D.,
72, 76, 203 n. 1; Gray, Asa,
24-5, 27-8, 48, 131, 257; Gur-
ney, K., 34; Haeckel, E., 69,
255; Harvey, W. H., 255;
Henslow, J. 8., 35, 75-6, 108-
9; 111, 122; Hooker, Sir
Joseph, 12, 15-16, 21-3, 30-1,
48, 51 n. 1, 64-7, 70-4, 104,
125, 129, 248-9, 254, 257-
8; Horner, L., 6, 86; Hux-
ley, T. H., 4, 83, 57-8, 67-
8, 74, 257; Jenyns (Blome-
field), L., 22 n. 1, 42 nm. 1;
Lankester, Sir Ray,72; Lewes,
G.H., 98, 262 n.3; Litchfield,
Mrs. (his daughter), 73; Lyell,
Sir Charles, 11 ». 1, 44, 47,
173,250-1, 254 ; Masters, Max-
well, 254; Meehan, T., 98;
Meldola, R., 255; Miller, F.,
, a a = »
INDEX 287
38 n. 1, 122, 127.2; Romanes, ology and natural selection,
G. J., 38,258 ; Scott, J.,18-19, 100-1; transmission of ac-
53n. 1,70, 74; Thiselton-Dyer,
Sir W., 100; Wallace, A. R.,
134 n. 1, 140, 255;
J 7 enner, 112; Weismann, A.,
1
Twenty-two of Darwin's let-
ters first published in these
addresses were written to the
following correspondents :—
Hope, F. W., 202-3; Trimen,
Roland, 63, 213-46; Weir,
J. Jenner, 32; Wilson, E. B.,
107; Wallace, A. R., 106 (see
also vii).
Autobiography of :—51, 58
n, 2, 59, 60, 63-4, 66, 74-6,
75 n. 2, 85 n. 1,99 n. 1, 100,
108, 123 n. 2, 140.
Darwin, Mrs. Charles, 58, 58
n. 2; letter from Darwin to
on 1844 essay, 6, 87; letters
signed by Charles Darwin writ-
ten by, 227-9, 234; letter
written on behalf of Charles
Darwin by, 216, 231, 245.
Darwin, Dr. Erasmus (grand-
father of Charles Darwin),
Lamarck and, 8, 4; A. R.
Wallace on, 15 ; on protective
and aggressive resemblances,
101-2.
Darwin, Erasmus Alvey (brother
of Charles Darwin), letter to,
58 n. 2.
Darwin, Francis, permission to
publish Darwin's letters
ranted by, vii, 31, 106, 201,
513 ; to reprint Section IV,
ix; assistance in editing let-
ters, &c., rendered by, 215,
224 n. 2, 245 n. 1, 273; pre-
sent at Oxford centenary, 78;
speech at, 79; thedebtto, 90-1;
on the conditions of Darwin’s
health and work, 58, 61-3, 61
n. 1; Darwin’s attitude to-
wards his readers, 69; Dar-
win's control, 75 ». 1; tele- |
quired characters, 38-42; an
orange-piercing moth, 224n. 1.
Darwin, Sir George, permission
to reprint Section IV granted
by, 1x; on discontinuity in
rate of evolution, 50-1; pre-
sent at Oxford centenary, 78;
ang ad i pg
etter si y Charles Dar-
win, 9445.
Darwin, Major Leonard, present
at Oxford centenary, 78.
Darwin, William E, present at
Oxford centenary, 78; speech
at Cambridge centenary, 79.
Darwin and modern science, Se-
ward, Ed., viii, ix, 92, 260.
Darwin celebration of the
American Assoc. for Adv. Sci.,
viii, 1, 57.
oes centenary at Cambridge,
Darwin centenary at Oxford, 78.
Darwin-Wallace celebration o
o~ goo Society, 12-15, 26,
52, 71.
Darwin-Wallace essay, publica-
tion of, vey 1, 1858), 12-15,
23, 144; effect of, 52; pro-
tective resemblance described
in Wallace’s section, 103;
sexual selection in Darwin’s,
103, 139-40.
Darwin - Wallace hypothesis,
xiv, xv, 8,9; see also ‘natural
selection’.
‘ Darwinism versus Wallaceism’,
Hubrecht, 269.
Davenport, C. B., 185; on de
Vries’s ‘ fluctuations’, 269-70.
Dawson, Sir William, on the
Origin, 15-16.
de Vries, on the variations in-
cluded in ‘ fluctuations’, 49,
49 n. 1, 263; Bateson’s, Pun-
nett’s, and Shipley’s ‘ fluctua-
tions ’ differ from those of, xi,
xii, 49 m; 1, 258-80; the mu-
tation hypothesis of, xi-xiv,
288
47,.265, 276; on the trans-
mission of acquired charac-
ters, 261-2, 270, 276; errone-
ously holds that Darwin's
views were consistent with his
own, xii, xili, 265; difference
between Darwin’s views and
those of, xii, xili, 48-4, 254-6.
decipiens, Danaida, 160.
deer, keen scent of, 242.
Descent of Man, &c., C. Darwin,
93, 104-5, 111, 113, 124, 126,
135, 140, 230, 230 n. 2, 231
n. 2, 233 n. 1, 2, and 3, 234
n. 4, 235 n. 1 and 2, 242 n. 2,
244, 245 n. 2.
desert plants, defences of, 96-8,
102-3 (see also 262 n. 3),
Detroit, 154.
Development and Evolution, Bald-
win, 48.
‘diana, Argynnis, 189-90, 207.
Diaposematism, 196-8, 208,
‘Different Forms of Flowers, &c.,
C. Darwin, 226 n. 1.
Diptera, of the Beagle at Oxford,
02; as mimics of Lycidae,
121; orchids and, 219, 223;
captured by Apocyneae, 225,
Disa, 220 n. 1 and 2, 222-4, 227.
barbata, 220 n. 1.
cornuta, 220 n. 1.
grandiflora, R. Trimen on,
217-18, 219 mw. 1, 222.
Discontinuity : see ‘ continuous
or discontinuous, &c.’
Dismorphia, Belt on, 135; fe-
males of , better mimics than
males, 139.
Disperis, 218-19, 221.
Dixey, F. A., on butterflies’
scents, 141-2; on mimicry of
L. astyanax by A, diana, 189.
dogs, Darwin on humour in, 244.
Dolichonyx oryzivorus, Beebe’s
experiments on, 142.
d’Orbigny, A., Darwin on, 6.
aos us, f. Danaida chrysippus,
Doubleday, H.,
butterflies, 242.
on sexes of
INDEX
Duncan, J. S., 95-6.
Duncan, P. B., 95-6,
Eastern States, 211.
Edinburgh, 245.
ie Review, 27, 28 n. 2,
Egybolis vaillantina, piercing
peaches, 224 n. 1.
Eigenmann, C. H., 201 m, 1.
Eltringham, H., 237, 239.
Elwes, H. J., 209.
Elymniinae, 161.
Emperor moth, 233 n. 3.
ser of Anat, and Physiol.,
Entomological Society of America,
eerey address to, 144-
Entomological Society of London,
202, 203 n. 1; Proceedings of,
128, 141; Transactions of,
116, 120, 141, 152 ”.1; 158
n. 3, 159. 1, 160”. 1, 164-
6, 169, 172, 183, 189, 195,
237, 242 n. 1.
eee Monthly Mag.,
Epigamic characters, 139-43.
Episematic characters, 112-13.
Erebia, 130.
Eresia, females of, better mi-
mics than males, 139. _
eros = floridensis, f. of L. archip-
pus, q.v. F
Ei aes mimicking Adelpha,
76.
erythromelas, Piranga, 142.
Essays on Evolution, Poulton, 98,
125 n. 4, 155, 282 n. 1, 237
n. 1, 274 n, I, 279.
Euclid, 100.
Eulophia, 218.
Euploea, 158 n. 3.
Euploea asyllus, 160.
brenchleyi, 160.
Euploeini, as models, 152;
mimicry between Danaini
and, 160.
Euralia, as mimics, 138,
a ii i
Euripus, as mimics, 133.
imitatriz, a mimic, 153.
Evans, John, on Archaeo-
Evening Primroses, de Vries
and, xi, 276.
Evidences of Christianity, Paley,
Darwin and, 100.
Evolution, rate of, 46-7, 50, 51;
continuous or discontinuous,
43-4, 48-51, 138-9, 200, 208,
254-6 (see also ‘ Mutation’) ;
ed and, 145-9, 200, 203,
Examinations, evils of, 88-9.
Exotic Butterflies, Hewitson, 237.
* External causes’, as interpreta-
tion of mimicry, 148; nega-
tived by the facts, 173-4,
205-6.
. Eye-spots on butterflies’ wings,
attractive to enemies, 231-2;
seasonal development of, 231-
2; Darwin and Trimen on
sexual selection and, 230 n.
2, 231-4, 233 n, 2 and n. 3.
Farmer, J. B., at Oxford cen-
tenary, 78.
wise: Vial, Darwin to, 20, 21.
Father and Son, 9, 10.
Fawcett, H., defence of Darwin
by, 2, 16-17, 82-3.
feelings of the sublime, 34-7.
Felton, 8., 101.
Female mimicry, 132-9, 240.
Fertilisation of Orchids, C. Dar-
win, 217, 219 n. 1, 224 ». 1
and n, 2, 229 n. 1.
fertilization, bearing of Men-
delian research on, 277-8.
Pity ears of Darwinism, New
ork, 1909, viii, xi, 3, 50». 1,
148, 201, 269, 270, 276.
‘ Fifty years of Darwinism’, Sec-
tion I, 1-56.
Fiji, 155.
, sea-weed like, 107.
Fiske, J., evolution in America
and, 2.
Fitton, W. H., 13.
U
INDEX 289
Fitz-Roy, 61, at Brit. Ass., Ox-
ford (1860), meeting, 66 n. 1.
Flora of Middlesex, Thiselton-
Dyer and H. Trimen, 234 n, 2.
gata be ae voc
oridensis, f. of L. archippus,
168-71, 205.
flowers, bright colours of, 113.
‘ fluctuations’ ,de Vries, Bateson,
_ Punnett on, xi, xii, 258-
‘Fluted swallow-tails’ = ‘ Pa-
pilio’, q.v.
Fly, as mimic of Lycidae, 121.
Forbes, E., 45: anticipated by
Darwin, 45, 123, 123 n. 2.
Forms of Flowers, C. Darwin, 25,
Fortnightly Review, 73.
Fossorial wasps, as models, 114-
16; Asclepiad pollen-masses
on true wasps and, 225 n. 2.
Foundations of the Origin o
Species, F. Darwin, Edr., 273.
Fox, W. D., Darwin to, 72, 76,
2038 n. 1.
fresh-water, ancestral forms in,
47.
frog, warning colours of a, 111.
From the Greeks to Darwin, Os-
born, 3, 4, 8.
fruits, bright colours of, 113,
113 n. 3.
Sullonica, Ophideres, 224 n. 1.
fur, thicker in north, 273.
Galapagos Islands, 251; Darwin
on colours of animals in, 127.
Galileo, effect of teachings of,
55-6.
Galton, Sir Francis, on heredity,
recession, and _ transilience,
xii, 266, 271, 273-4, 276; on
freedom conferred by the
Origin, 52.
Ganoid fishes, ancestral, 47.
Gardener’s Chronicle, 224, 227.
Gartner, Darwin on, 58, 53 m. 1.
—" of Species, St. G. Mivart,
genutia, Danaida (Salatura),
158-9, 158 n. 3, 161-2.
oe
290
Y oR spinosum, defence of,
glandulosa, Clematis, 71.
Glaucus, group of ‘ Papilio’,
182-3.
glaucus, Pap., 182-5, 188, 206.
Godman, Dr. F. D., 209.
Godman-Salvin Coll., 195.
Gosse, Philip, 9-11.
Gower, H., 221.
Grand Canyon of the Colorado,
37
grandiflora, Disa,217,219 .1,222.
Grapta (Polygonia), 175.
Gray, Asa, sure insight of, x;
Darwin and, 1, 2, 22-5; ex-
tracts from Darwin’ s letter to,
published in joint essay, 23 ;
_ on the Origin, 23; on Cypri-
pedium, 224, 224 n. 2; ; on
Habenaria, 998- 9. Darwin to,
24-5, 27-8, 43, 131,257. To
Darwin from, 23,
Gray, G. R., 214.
Greenland, 46.
Griffith, George, on Oxford Brit.
Ass. (1860) meeting, 66 n. 2.
grossulariata, Abraxas, 242 n. 1.
Grove, Dr., on Tennyson and the
ly 2. jaa) a
Gryllus (Acridian), resembli
Svea 96-8. =
Guatemala, 192, 208 7. 1.
Guerrero, 182.
Guiana rock-thrush, 140.
Gulf of Mexico, 176, 186.
Giinther, Dr. A., 107.
Gurney, E., on 'vivisection, 73;
Darwin to, 34.
Gynanisa isis, 230 n. 2, 233,
233 n. 3.
Haase, E., 137, 177-8, 181, 189.
Habenaria, 229,
Haeckel, E., on memory and
heredity, 38 ; on transparency
of oceanic forms, 105; Dar-
win to, 69, 255.
hahneli, Pharm., 179.
Hall, American Palaeontology
and, 3.
INDEX
Hallett, on improvement _ of
wheat, 48.
Halley, Newton and, 86. ay
Hamadryas, 152.
Harcourt, A. G. Vernon, 66 n. 2,
Hardwick, 234.
hare, concealment of, 113.
Haredene, Darwin’s residence
at, 245, ae n. 1.
Harvey, W. H , 218, 220, 220
n. 1 and n. 2, "054-5.
health, work essential for Dar-
win’s, 59-66, 216, 256-8, :
‘ Heliconidae’, 239. ?
Heliconinae, 158, 239. :
iespexs as mimics, 116-18,
7". .
Henfrey, A., 13.
Henslow, J. 8., and Darwin, 4,5,
85-6, 88; Darwin to, 35, 75-6,
108-11, 122,
Heredity, eee Thomson, 271. i
heredity, beari
of Mendelian 4
research on, 277-8: see also
‘acquired characters’ and
‘fluctuations ’.
mone on memoryand heredity,
Herschelia, 222.
Hestia, 152.
heterostyled Owalis, 226, 226
n« 1, 227.
Hewitson on mimicry, 237-40,
History and arrangement of Ash-
molean Museum, P. B. Dun-
can, 95-6.
Hobart Town, 202.
Holland, W. i 2 171, 211-12.
Homer, 280.
Hong-Kong, 155, 156.
Hooke, Newton and, 85.
Hooker, Sir Jose h,45; Darwin’s
eat friends ip with, -and
elp received from, i, 2,
12-18, 21-2, 25, 64-7, 70-1,
123 n. 2, 124, 221.
Darwin to, 12, 15-16, 21-3;
30-1, 38 n. 1 "48, 51 n. As
64-7, 70-4, 104, 125, 129,
248-9, 254, 257-8.
Hooker, Sir William, 36.
Sn » *
7 il 7; o ;
INDEX
Hope Department, Oxford, Dar-
win's letters in, 31-2, 201-3;
will help in work apn N.
American mimicry, 210.
Hope, F. W., Darwin and, 201-3,
208 n.1; Darwin to, 202-3,
first published in Section V.
Horner, L., Darwin to, 6, 86.
Horsfield, T., 178.
Hubrecht, A. A. W., xii, xiii;
on de Vries's ‘ fluctuations’
hereditary, 267-9.
Hudson, N. Y., stripeless L.
archippus at, 211.
Hudson’s Bay, 176.
‘Hugo de Vries’s Theory of
Mutations’, Hubrecht, 267.
hulsti, f. of L. archippus, 167,
171-2, 205.
humble-bee found dead on As-
clepias flower, 225 n. 2.
Humboldt, Darwin on, 35.
humour in dogs, Darwin on, 244.
Huxley, Julian, 78.
Huxley, T. H., 38 ». 1, 61,61 . 2;
defence of Darwin by, and
Darwin’s friendship with, 25-
6, 53-4, 66-8, 89, 124, 255; on
Lyell, 5; influence on teach-
ing of, 53; on teleology, 97
n.1; Darwin to, 4, 33, 57-8,
67-8, 74, 257.
Huxley, Mrs. T. H., 243.
Hyatt, A., 2; American Palae-
ontology, and, 3.
Hymenoptera, as mimics, 120;
orchids and, 223; Asclepiad
ee on, 225-6, 225
n. 2.
Hypolimnas, as mimics, 138.
merce misippus, as mimic,
h thesis, Darwin on value of,
"26.
Tliad, 280.
imitatriz, Eutresis, 1538.
— colours, Darwin on,
9
individual adjustment, power of,
41-2, Thi adesd
291
individual differences claimed
as mutations, 270-80: see
also ‘ fluctuations’.
In Memoriam, 8, 9.
insolata, Danaida, 160.
‘internal causes’, as interpreta-
tion of mimicry, 148.
Introduction to Entomology,
Kirby and Spence, 118: see
also 99. ne
isis, Gynanisa n. 2, 288,
233.3. |
isolation, ancestral forms pre-
served by, 46-7.
sar le as models, 153-4,
Ituna, F. Miiller’s theory and,
153-4,
Ituna phenarete, as model and
mimic, 153
James, William, on Psychology
and natural selection, 3.
Japan, 156.
Java, 156.
Jen, Zeit., 141.
Jenyns, L. (Blomefield), Darwin
to, 22 nm. 1, 42 n. 1.
johnstoni, Acraea, 130.
Joint essay of Darwin and
Wallace: see ‘ Darwin-Wal-
lace essay’.
Jordan, Karl, on the genera in-
cluded in ‘ Danaida’*, 152 n, 1,
158-9, 158 n. 3, 159 n. 1: see
= ‘Rothschild and’, 178,
Journal of Researches, &c., C.
Darwin, 109, 111.
Judd, J. W., on debt to science
felt by Darwin, 65; present
at Oxford centenary, 78.
Kerner, 219 n. 1.
Kew, 221.
a Dr., 95. beh
imanjaro, 130.
King George’s Sound, 202,
King’s College Chapel, 37 n. 1.
Kingsley, C., on Omphalos, 10,
U2
292
Kirby +e i apaaaie teleology
and, 99,
‘ Kite erallow tails’ = cosmo-
desmus, q
= id, f. of D. " chrysippus, 157.
Kélreuter, Darwin on, 53.
Kosmos, 128.
Krefft, Dr. G., 106.
st a on Oph. fullonica, 224
n-4.
Lagriidae, as mimics, 120,
eee Erasmus Darwin and,
4
Lamarckian evolution, xiii ; ac-
quired characters and, 33-42,
275 (see also xiv, xv).
Lamellicorn, sexes of, 233 n. 1.
Landor, W. S., 61, 61 . 2.
Lankester, Sir Ray, on T. H.
Huxley, 26; on Lyell, 86;
Darwin to, 72.
Lasiocampa quercus, males of
‘assembling’, 230 n. 2, 235,
235 n, 1, 242, "942 n, 1.
leda, Melanitis ‘(Cylllo), 230 n. 2,
238, 233 n. 2.
Leibnitz, 129.
Leidy, J., American Palaeonto-
lo and, 2.
Lepi optera, orchids and, 223;
oe ahi by Physianthus, 225
n
Lepidosiren, 47.
lerna, Adelpha, 192.
levana, Araschnia, 176.
Lewes, G. H., review of Animals
and Plants by, 68 ; Darwin to,
98, 262 n. 3.
Life and Letters of Charles Dar-
pase? = Darwin, Edr., 5, et
ih ae Letters of Sir Charles
Lyell, Mrs. Lyell, Edr., 249 n.2.
Life and Letters of T. H. Huzley,
L. Huxley, 27, 97 n. 1.
Light, Darwin on birds and
moths attracted by, 243.
Limenitis, 152.1; evelation and
theories of mimicry in relation
to, 174-6, 205; relationship
INDEX
to Adelpha of, 192-8; recent
changes in mimetic, 199,
Limenitis archippus, evolution -
from L, arthemis
of, 137-8, 164-8,
172, 186-8, 204-5 ;
continuous evolu.
tion of, 165-8;
floridensis derived
from, 168-71, 205;
hulstiderived from,
171-2, 205 ; stripe-
less form of, at
Albany, 166 n. 2,
211-1 : see also
155, 161, 199.
arthemis, archi;
derived from, 137-
8, 164-8, 172, 186-
8, 204-5; astya-
nax derived from,
172,186-8,205,207.
astyanax, evolution
rom L. arthemis
of, 172, 186-8, 205,
207 ; female Arg.
diana a mimic of,
189-91, 207; phi-
lenor and its ‘ Pa-
pilio* mimics, mi-
micked by, 186-91,
207: see also 199.
bredowi, a 8. f. of
californica, has a
greater likeness to
Adelpha, 192-3,
197, 207-8.
californica, resem-
blances between
lorquini and, 191-
200, 208.
yey Bes sees,
rom archippus,
168-71, 205.
hulsti, deriyed from
archippus, 171-2,
205: see also 167.
lorquini, resemb-
lances between
californica and, di-
minishing N. of
¥ re re!
\ ‘ 7 2S a
—_—s el
INDEX 298
Limenitis lorquini (continued): —
eir overlap, 191-
200, 208; as a pos-
sible standard of rate
— change,
weidermeyeri, 196.
Limnas, 156-8, 158 n. 8, 204:
see also ‘Danaida’.
Lingula, 47.
Linnean Society of London, 217,
219, 222, 253; Trimen’s
r on mimicry read
at, 241; Journ. Proc. Bot.,
222 n. 2, 227, 229, 229 n. 1;
Journ. Proc, Zool., 103, 110,
139, 246 n. 2; Trans., 122,
225-6, 236: see also ‘ Darwin-
Wallace Celebration, &c.’
Linum, 223.
Linum perenne, 224.
Litchfield, Mrs., Darwin to, 73.
: a ong 3 —_ Science’, in
imes Lit. Suppl., protest
inst, 79-83.
Livingstone, D., 98.
Lizard, attracted by butterfly’s
‘eye-spots', 231, 232.
Lock, R. H., on de Vries’s ‘ fluc-
tuations ’, 262, 270, 271.
Locustidae as ant mimics, 116.
Long Island, 186.
Longicorn beetles as mimics,
114, 115, 120-2; sexes of,
233, 233 n. 1.
Longstaff, G. B., on chameleon,
“+t on scents of butterflies,
lorquini, Limenitis, 191-200, 208,
"B10.
Lubbock, Sir John, see ‘ Ave-
bury’.
Luteva macrophthalma, Burchell
on mimicry in, 117-18.
Lycid beetles as models, 118-21.
Lycoraeini, ancient 8. American
Danaines, both mimics and
models, 153-4.
Lycorea, 153.
Lyell, Sir Charles, 10, 15, 24-5,
, 45, 61, 88, 248; Darwin's
debt to, 4-7, 86-7; Darwin
urged to publish by, 12; part
in the a! hg meg of joint
essay taken by, 13; on single
centres of creation, 249-53;
Darwin to, 11 n. 1, 44, 47,
178, 250-1, 254; to Darwin, 7;
to Hooker, 249.
Lysander group of section
‘ Pharmacophagus’, 178.
Macdonell, A. A., 264.
MacGibbon, J., 227,
machaon, a type of section
‘ Papilio’, 177; and type of a
group of that section, 182-3.
Macmillan’s Magazine, 16.
“rae hiancbonaey ais 117.
agascar, 177.
Magpie moth, 242 n. 1.
Malay archipelago, 156.
Malayan Swallow-tails, Wallace
on, 132, 236, 238-9.
male butterflies, scents of, 141-2.
Malvern, 224.
Mantis, 117.
Mars, 251.
Marsh, 0. C., American Palaeon-
tology and, 2; on Archaeo-
pteryx, 29, 30.
Marshall, G. A. K., on S.
African ant mimics, 116; on
8. African mimics of Lycidae,
118-21; on use of butterflies’
eye-spots, 232.
Massachusetts, 211.
art: Maxwell, Darwin to,
‘Meadow Brown’ butterfly,
eye-spots of, 232.
Meehan, T., Darwin to, 93.
melanie forms and mimicry,
136, 138, 184, 206-7.
Melanitis (Cyllo) leda, Darwin
and Trimen on, 230 n, 2,
233, 233 n. 2.
melasina, f. of Pap. polyxenes
americus, 184.
Meldola, R., at Oxford cen-
294
tenary, 78; notes on mimicry,
&c., sent by Darwin to, 106,
. 126-9; Miillerian mimicry
introduced by, 128-9; on
butterflies’ ‘eye-spots’, 231;
on ‘acquired characters’ dis-
cussed in Origin, 273; Darwin
to, 127, 129, 255.
Melyridae, as mimics, 120.
Memory, heredity and, 38, 38 n.
1,40; adaptation evident in, 40.
Mendel, Gregor, effect on evo-
lutionary thought of, 276-9.
Mendelism, Punnett, 258, 259,
262, 279.
Mendelism, xiii, xiv ; ‘acquired
characters’ and, 3, 39, 275;
N. American butterflies favour-
able for experiments in, xiv 7.
1, 185-6, 188, 208-9.
Mendel’s Principles of Heredity
(1909), Bateson, 259.
Mendel’s Principles of Heredity :
A Defence (1902), Bateson, 52.
Mesembryanthemum, Burchell on
8. African stone-like species
of, 96-8 ; truncatum, 96 ; tur-
biniforme, 96.
Messiah, 257.
Métamorphoses, Meurs et In-
stincts des Insectes, Blanchard,
235 n. 1.
Methods and Scope of Genetics,
Bateson, 277.
Mexico, 180, 182, 186 m. 1, 192.
Mill, J.S., on the logical method
of the Origin, 17.
Milton, 60, 77, 111.
Mimicry, vii; definition of, 145;
protective resemblances and,
145-7, 174-5; Batesian and
Miillerian defined, 149-50 (see
also 118-21); Bates’s memoir
on, 122-6, 236, 238-40; Wal-
lace’s memoir, 236, 238-9;
Trimen’s memoir, 230 ». 2,
231, 236-41 ; Miiller’s paper,
126-9, 240; Darwin’s interest
in memoirs, 123-9, 144-5, 240-
1; Darwin’s anticipation of
Bates, 46, 123-4; reciprocal
INDEX
mimicry, 197, 208; secondary,
182-8, 188, 190-1, 207; ter-
tiary, &c., 207 ; melanic forms
and, 136-8, 184, 206-7; initial
resemblances and, 180; evo-
lution (continuity, mutation)
and, 138, 145-9, 200, 203; na-
tural selection and, 123-4, 131-
2, 148-9; sex, sexual selection
and, 127-8, 132-9, 148,149 ».1,
182-3, 238, 240; ‘external
causes’ suggested for,148, 173-
4, 205-6; ‘internal causes’
suggested for, 148 ; the bear-
ing of N. American butter-
flies on theories of, 144-212 ;
examples of, observed by
Burchell, 114-22 ; prejudice
against, 130.
‘Mimetic North American
species of the Genus Limeni-
tis, &c.’, Poulton; 152 n. 1.
misippus, Hypolimnas, 161.
Mississippi Valley, 170, 181, 186.
Mitchell, P. C., at Oxford cen-
tenary, 78. '
Mivart, St. G., attacks of, 30-2;
Darwin’s replies to, 104, 255.
monad, 47.
monstrosities, see ‘ mutation ’.
Moore, Aubrey, on argument of
Omphalos, 11
Moore, F., Danaine genera of,
154, 156, 158, 159.
Moral Philosophy, Paley, 100.
More Letters of Charles Darwin,
F. Darwin and Seward, Edrs.,
4, et passim. ;
Morgan, Lloyd, on OrganicSelec- _
tion, 8, 48; on chameleon
and snake, 97.
More, E. S., on colours of shells,
5.
Moseley, H., 78.
Moseley, H. N., 79.
Moths, mimics of ‘ Papilio’, 180;
fruit pierced by, 217, 224, 224
n.1, 227; orchids and, 219;
brightly coloured beneath,
2380 n. 2 ; light and, 243,
Moulton, J. C., on mimicry be-
INDEX
bo we Teas and Danaini,
Miller, F., 151, 164; hel
Darwin by, 2 ; on butte
scents, 141; on sexual a
tion and mimicry, 127-8, 238;
Darwin to, 88 ». 1, 122, 127
Millerian Mimicry, defined,
149-50, see also 114-32, 153-4;
warning colours and, 175-6;
African Lycid mimics and,
118-21; American Dana-
ine mimics and, 174-7, 205;
N. American Ph. philenor
mimics and, 189-91, 207;
Darwin's interest in, 126-9,
144-5; strong opposition to,
129; reason for slow accep-
tance of, 129.
a e origins, 3; Darwin on,
47-53.
Murray A., on an alternative to
natural selection, 19; on dis-
tribution of beetles, 246 n. 2.
Murray, John, 31.
music, the thrill of, 37 ;
and, 37 n. 1, 60.
Mutation, xiii-xiv, 3, 39, 259-60,
265 ; de Vries’s theory of evo-
lution by, xi, xiii, 276 ; Dar-
win's disbelief in evolution by,
v, xii-xiv, 42-7,254-6 ; certain
facts of mimicry opposed to,
147-8, 164-8, 166 n x 200, 208,
211- 12; Darwin's individual
differences sometimes claimed
as, 49 nm. 1, 279-80.
Mutationstheorie, de Vries, xii,
xiii, 262-5, 263 n. 1.
mutilation, Darwin on non-
Darwin
inheritance of (1844), 273.
Mylothris owe ris) pyrrha,
rwin and Wallace on mi-
micry in female of, 134 n. 1.
N. America, butterflies of, speci-
advantageous as intro-
duction to study of mimicry
and its bearing on evolution
and past history and lines of
295
migration, vii, 144-212 ; also
for testing Mendel’s law in
nature, xiv ». 1, 170, 185-6,
188, 208-9 ; insects of, held
by Asclepiad flowers and bear-
ing P mae of, 225-6,
N. poe 224 n. 1.
N. Nha Darwin’s trip to with
Pe 203 n. 1.
Nigeli, C. Darwin on, 20-1.
Najas: see Limenitis lorquini
and populi.
Natural History Review, 125-6,
228, 228 n. 1.
natural selection, at first mis-
understood by naturalists,
32-3, 129-31; individual sus-
ceptibility and, 42, 143 ; adap-
tation and, 99-101; mimicry
and, 123-4, 131-2, 148-9,
200-1: see also ‘ Darwin-Wal-
lace essay ’.
Natural Selection, Essays on,
A. R. Wallace, 111, 112.
Natural Theology, Paley, 95.
natural versus artificial selec-
tion, 278-9.
uct rire in Nicaragua, Belt,
1.
Naturalist on the Amazons, Bates,
Nature, 252, 255, 256.
nectarine and peach, 251.
Neoclytus curvatus, as mimic, 115.
Neo-Lamarckism, 3.
Nevada, 192-3.
New England, 211.
New Mexico, 176.
Newton, Darwin and, 55-6, 77,
90; nearly lost to science, 57,
85-6 ; Hooke and, 85; Halley
and, 86; Leibnitz and, 129.
Newton, ie 30, 89.
nigricans, Phryniscus, 110, 111.
niphe, Argynnis, 161.
on of colours, Werner,
North American Review, 31.
a Territory, Canada,
296
‘Notes on Fertilisation of Or-
chids’, C. Darwin, 229 n. 1.
‘Notes on the Geographical
Distribution and Dispersion
of Insects, &c.’, R. Trimen,
246 n. 2.
Novitates Zoologicae, 152 n. 1,
158, 178.
‘Oak Eggar’ moth, 235 n. 1,
242, 242 n. 1.
Ocellated spots on butterflies’
wings, Darwin and Trimen on,
230 n. 2, 231, 232, 233, 233 n. 2
and n. 8, 234.
Octopus, Darwin on variable
protective resemblance of,
108, 109.
Oecology and natural selection,
xiii, 143.
Oliver, D., on tendrils, 74; present
at reading of joint essay, 13.
Omphalos, P. Gosse, 9-12.
‘On some remarkable Mimetic
Analogies among African
Butterflies ', R. Trimen, 236.
‘On the Geographical relations
of the chief Coleopterous
Faunae’, A Murray, 246 n. 2.
‘On the Phenomena of Varia-
tion and Geographical Dis-
tribution as illustrated by the
Papilionide of the Malayan
Region’, A. R. Wallace, 236.
On Variation, Bateson, 274.
Ophideres fullonica, piercing
oranges, 224 n. 1.
Orange River, 96.
oranges pierced by moth, 224.1.
orchids, Darwin and Trimen on
fertilization and structure of,
217-29, 232.
Oregon, 192-4.
organic selection, 3, 48.
Oriental Region, butterfly
models and mimicry in,
152-3, 156, 160-1, 177, 179-80.
Origin, ¢. Darwin, v, ix, xiv, 2,
et passim; Owen criticized in
the, 28; effect of the, 51-6;
adaptation and the, 99 n. 1;
INDEX
Paley quoted in the, 100;
‘individual differences’ the
steps of evolution in the, 272
n. 1, transmission of acquired
aes considered in the,
Ornithoptera, 179.
Ornithoptera croesus, sexes of,
233 n. 1.
Ornithorhynchus, 47.
Orthoptera, as mimics, 116.
oryzivorus, Dolichonyx, 142.
Osborn, H. F., American Palae-
ontology and, 2; on organic
selection, 3,48; on Erasmus
Darwin and Lamarck, 3-4; on
In Memoriam, 8.
Owen, Sir Richard, 15; Darwin
and, 26-30, 28 n. 2, 230.
Oxalis, Darwin and R. Trimen
on, 217, 223-4, 226-7, 229.
Oxford, Buckland, Lyell, Darwin
and, 6-7, 86-7; Brit. Ass.
Meeting (1860) at, 66-8 ; Dar-
_ win Centenary at, 78-83.
Pacific States, 207-8.
Palaearctic Region, mimicry in
W. section of, 150; in E. see-
tion of, 151.
palamedes, Pap., 183, 206.
Paley, influence on natural his-
tory of, 95-8, 100-1; quoted
in Origin, 100.
Pall Mall Gazette, 68.
pamphilus, Coenonympha, 231-2.
Pangenesis, 33-4, 38-9, 38 n. 1.
‘Papilio’ or ‘Fluted Swallow-
tails’, one of the three sections
of Papilionidae, 137, 177-8, 206;
‘Anchisiades ’, ‘glaucus’,‘* ma-
chaon’, and ‘troilus’ groups of,
182-3; as mimics of Pharmaco-
phagus, 187, 177-91, 206-7 ; of
Pharm. philenor in N. America,
181-91, 206-7; of Danainae,
&c., 137,179; secondary mimi-
cry between, mimetic, 182-3,
207 ; females of, especially mi-
metic, 132, 137, 189, 179, 182-
5, 206, 236-7, 278; Oriental
INDEX
— of, greatly mimicked,
‘Papilio’ polyxenes americus, 184.
asterius, 182-
, 188, 206.
sarpedon choredon, 106.
dardanus ( pe) 132,
139, 236-7,
glaucusglaucus(turnus),
182-5, 188, 206.
palamedes, 183, 206.
troilus troilus, 182-5,
188, 206.
Papilionidae, see ‘ Cosmodesmus’,
‘Papilio *, and ‘ Pharmacopha-
Patagonia, Darwin on colours of
ae ager in, 127. 017, 204,
peach, moths piercing, 217,
224'n. 1, 22 2h nectarine and,
251.
Peacock, butterflies’ ‘eye-spots '
and tail of, 231, 234.
Peckham, Dr. and Mrs. G. W.,
on mimicry in Attid spiders,
116-17.
Pelargonium, defence of desert
species of, 98
perenne, Linum, 224.
Perrhybris (Mylothris) pyrrha,
Darwin and Wallace on mi-
micry and sex in, 134 n. 1.
Peru, 184.
‘ Pharmacophagus’ or ‘ Aristo-
lochia swallow-tails’, one of
the three sections of Papili-
onidae, 177-8 ; as models, 137,
177-91, 206- 7; ; distribution of,
177-80 ; New World species
of a distinct group, 180-1,
206 ; ‘tailed’ forms of primi-
tive, 181; females of S. Ameri-
can species mimicked, very
Pt meee, ceo he
. rmacophagus’ philenor, a
modelof N. Ameri-
can species of ‘Pa-
ilio’, &c., 180-
1, 206-7; special
rotection of, 181.
ydamas, 180.
phenarete, Ituna, 153.
Paaiictetie, leaf-like, 101.
Physianthus albens, 217; Dar-
win and R, Trimen on in-
— captured by, 225, 225
Physiology and vivisection, Dar-
ae ca 7 :
phagous beetles as mimics,
12041.
Pierinae, 1384 n. 1, 135, 139;
Pharmacophagusmimickedby,
Piranga_ erythromelas, Beebe’s
experiments on, 142.
Planaria, Darwin on mimetic
species of, 122.
Planema, as model, 238.
Plateau, F., on taste of Magpie
moth, 242 n. 1.
plexippus, Danaida (Anosia),
152 nm. 1, 154, 158-9, 158 n. 3,
161-4, 168- 73, 177, 204,
Pneumora, 230 n. 2.
Pocock, R. I., on mimicry in
Attid spider, 117.
podalirius, a type of ‘ Cosmodes-
mus’, 178.
poetry, Darwin and, 60: see
also vi, 57-66, 79-83, 216,
256-8,
polydamus, Pharm., 180.
Polygonia ( (Grapta), 175.
polyphyletic, see multiple
origin,
Popular ‘Science Monthly, 267.
sete Limenitis, 193.
oulton, E. B., 78; on ‘ eye-spot’
of butterfly, 231- 2; on ac-
quired characters, 274 n. 1.
Positon! E. P., 79.
Prieska, 96.
Primula, 229.
Principles of Geology, Lyell, 5,
6, 9». 1, 86.
Proc, Am. ‘Acad., 24,
Promeces viridis as mimic, 114,
298
proserpina, a-probable hybrid
between 2 arthemis and
astyanax, 186.
protective resemblance, aggres-
sive and, 101-10; mimicry
and, 101, 145- 7, 174-5,
Paeudacra ea, & mimetic genus,
pseudodorippus, f. of Lim. archip-
pus, 211.
Punnett, R. C., on de Vries's
: fluctuations’ non-transmis-
sible, xi, 258-80; individual
differences claimed as ‘ muta-
tions’ by, 279-80.
purpurata, Radena, 158 n. 3.
pyrrha, ours (Mylothris),
n,
Quart. Journ. Micr. Sci., 224
n.
Quarterly Review, xiv, 13 n. 2,
16 n. 4, 28 n. 2, 30, 44, 47,
254, 260, 280 n. 1.
quercus, Lasiocampa , 230 n. 2,
235, 235 n. 1, O49, 242 n. 1,
ee Darwin on white tail of,
Radena purpurata, 158 n. 3.
Rambles of a Naturalist, &c.,
Collingwood, 124.
Reader, 228.
Reciprocal mimicry, a probable
example of, 196-8, 208.
recognition markings, 112-13.
red cabbage, 249.
Regeneration, Darwin
others on, 38 n. 1.
edie Strelitzia,217, 228-9, 228
and
st tee on Mimicry, Haase,
eae Bateson on causes of,
Rhodesia, S.E., 180.
Rhopalocera Africae Australis,
R. aa 228 n. 1,
ax
a,
INDEX
Riley, C. V., on variable’ a
tive resemblance, 109.
Rio de Janeiro, 35. ;
Rio Macao, 35.
rock-thrush of Guiana, 140.
Romanes, G. J., on Darwin’s ex-
rpg oan of ‘the sublime’,
; Darwin to, 38, 258.
Rothiehtit and Jordan, on
two ae digo 158; on
synonym Papilionidae,
152 n. ih 7182 n. 1; on classi-
fication of Papilionidae, 178;
on structural distinction: of
7 ida Pharmacophagus,
Rowe, Arthur W., on ‘ continu-
ous’ evolution in the white
chalk, 280 ». 1.
Royal Institution, 67.
Royal rig of Edinburgh, Proc.
of, 19, 44.
ms OF Society, Phil. Trans. of,
Rugby School Nat. Hist. Soc., 109.
S, America, Darwin and Wallace
in, 1; Ap sinter ig Tena of,
98 ; forms in of, 46;
butterfly models of, 153-4;
invaded by Danaida from N.,
163-4, 204.
Salatura, see Danaida decipiens,
genutia, and insolata.
Salisbury Lord, D.C.b. ot to
Darwin in 1870 b
vag! eer scl bes | by Scyllaea,
107, 108.
Saturnidae eye-spot in 8. African
species of, 233.
“oe mimics of ‘ Papilio’,
1
Satyrium, 220-1, 220 n. 2, 229.
Scarlet tanager, 142.
Scent of butterflies, 141-2, a 85
preciation of, by insects, 2
235 n. 1, 249, 242 n. 1; and
deer, 242,
INDEX
Scotsman, 44.
Scott, D. H., at the Oxford
centenary 78.
ap wygk Jig help iven by Darwin
rwin to, 18-19,
33 n. I 70 74.
Scott, W. B., "American Palaeon-
tology ogy and, 2
Scudder, 8. on N. American
butterflies, 152 n. 1, 165, 169
n. 1, 172, 176, 186, 188, '189-
90, 193.
Seyllaea, , asea-weed-like mo]lusc,
sea-sickness, probabl
cause of Darwin’s i
58 n. 2.
season, ‘
wet, 23
secondary and tertiary mimicry
in N. American butterflies,
182-8, 188, 190-1, 207.
Sedgwick, A,, Darwin taught by,
85; on Origin in review, 16
n. 4; and in letter to Darwin,
16, is, 89.
Seeley, hy G., on Archaeo-
not
-health,
a developed in
pteryx
segregation of varieties, 125.
Semnopsyche, see ‘ Argynnis
diana’,
ae R,, on memory and here-
"hoa A. C., 4.n. 1, 92.
ae mimicry and, 132-9, 182-3,
0.
sexes, relative numbers of, in
butterflies, 233-5, 233 n. 1,
234 n. 4, 242.
sexualselection, 139-43; Darwin’s
— interest in and descrip-
ion of, in joint essay, 103, 111,
113, 125-8, 139-40 ; the origin
of species and, 125 ; mimicry
and, 127-8, 148, 149 n. 1, 238,
240 : sounds and scents of in-
sects as evidence of, 141-2;
Darwin on, in letters to Tri-
men, 230-6, 24
Shakespeare, 62, 77, 730, 90.
299
Shipley, A. E., on de Vries’s
‘fluctuations’ non-transmis-
sible, 49 n. 1, 258-9, 265,
shorthorn cattle, 249,
Silurian, 47.
‘single centres of creation’,
— igo and Lyell on, 248-9,
‘Small Heath’ butterfly, value
of eye-spots of, 231-2,
Smith, Geoffrey, 79.
Solomon Islands, mimicry in,
160.
Sound-producing organs as
oar of sexual selection,
Species and Varieties ;
Origin by Mutation, de Vries,
49 n. 1, 259, 265-7.
speciosa, Bonatea, 217, 228, 229,
var 3 1, 16
Spectator, 9 n. n. 4,
Spencer, Herbert, 2; acquired
characters and the theories
of, 33-7.
Sphex, as model, 114, 118.
Spiders, as mimics, 116-17; mi-
metic males of, 133.
se and thorns, 98, 262
nu. oO.
St. Helena, 71.
thir
Strecker, 168, 311.
Strelitzia reginae, fertilized by
oe 217, 228-9, 228
n. 2.
strigosa, f, of Danaida berenice,
154, 162-4, 171-2, 204-5.
struggle for existence, the
essential feature of Dar
winism, 8, 9; rate of evolu-
tion determined by, 46-7;
adaptation, natural selection
and, 94-101.
sublime, feelings of the,
Sugar-bird, see ‘ sun-bird ’.
Sun-bird, Strelitzia fertilized by,
-9, 228 n. 2.
800
Sybilla, Limenitis, 164.
Sydney, 202.
‘Tails’ of Phorasiehaet:
primitive, 181.
tanager, scarlet, 142.
Tasitia, see ‘ Danaida berenice’
and ‘ D. strigosa’.
Tasmanian insects of Beagle,
T Teo! d ad
eleolo an aptation,
9 vid Pp
Telephoridae as mimics, 120.
Tendrils, Darwin on origin of,
73-4.
Tennyson,
and, 8, 9.
Thackeray, F. St. J., on Tenny-
son and evolution, 9n.1.
Thayer, A. H., on white under
sides of animals, 109, 110.
Thiselton-Dyer, Sir William,
234 n. 2; at Oxford cen-
tenary, 78; on _ protective
adaptations of plants, 97 . 1,
102 n. 2; on origin from a
single pair, 252-3; Darwin
to, 100.
Thomson, J. Arthur, on de
Vries’s ‘ fluctuations’, 271.
Thomson, Sir Wyville, 256.
thorns and spines, value of, 98 ;
origin of, 262 n. 3.
Thyridia, F. Miiller on Ituna
and, 153-4,
beer Darwin on the stripes of,
Times, 49 n. 1, 68, 79.
toad, warning colours of ay
110, rT,
transilience, 274, 276.
transmission of acquired char-
acters, Weismann on the, xv,
8, 33-42, 274-5; F. Darwin
on the, 38-42; de Vries on
the, 261-2, 270, 276 ; C. Dar-
win on the, 273; Poulton on
the, 274 n. 1,
Travels in the Interior of Southern
Africa, Burchell, 96-7,
natural selection
INDEX.
ys seg Darwin on the, 99
Tres ‘Marias Islands, 181.
Trichius, sexes of, 233 n. 1.
Trigonia, 47.
Trimen, Henry, 234 n. 2.
Trimen, Roland, first meeting
between Darwin and, 213-
14, 219; on Darwin and
Owen, 28° n. 2, 230; on Dar-
win’s help to younger men,
215 ; contributions to Descent
of Man by, 230 n. 2; on fruit-
piercing moths, 224, 224 n.1,
227; Ozxalis sent to Darwin
by, 226-7, 226 n. 1; on fer-
tilization of Strelitzia, 228 n.
2; on ‘eye-spots * of Melanitis
leda, &c., 230 n. 2, 231, 233,
233 n. 2 and 3; on sexes of
African butterflies, 234 n. 4;
apers on Disa and Bonatea
y, 217-18, 222, 224, 228-9,
229 ».1; on distribution of
beetles by, 231, 246, 246 n. 2 ;
memoir on mimicry by, 231,
236-41 ; 18 unpublished let-
ters (1863- 71) from Darwin
to, vii, 63, 213-46, 256 ; from
Mrs. Darwin to, 216, 245.
trimorphic Oxalis, 226, 226 n. 1.
Troilus, group of ‘Papilio’,
182-3.
troilus, Papilio, 182-5, 188,
206.
tropical forest, feelings excited
by, 34-7.
turkeys, white moths rejected
by, 112, 112 n. 3.
Turner, H. H., on Newton, 57,
85-6.
turnus, mimetie female f. of
Pap. glaucus, 182-3, 185.
BS ra J., Belfast address of,
Uitenhage, Lycidae and mimetic
Longicorn found together by
Burchell at, 121.
INDEX
‘unit character’, Castle's defi-
nition of, 276, 278.
ursula, see ‘ Limenitis astyanax’.
vaillantina, Egybolis, 224 n. 1.
value of colour in struggle for
life, 92-148.
Vancouver Island, 193, 196.
Variable protective resem-
blance, 108-10.
—s Bateson on causes of,
Variation, Heredity, and Evolu-
tion, Lock, 262, 270.
Venezuela, 184.
Verhandl. d. V. Internat. Zool.
Congr. z. Berlin (1901), 155.
Vestiges of the Natural Hi.
t) sree, R. Chambers, 28,
Vine-tendrils, 78-4.
Vines, S. H., at Oxford cen-
tenary, 78.
viridis, Promeces, 114,
Vivisection, defended by Dar-
win, 72-3.
Walcott, C. D., American Palae-
ontology and, 8.
Walker, F., 202, 203 n. 1.
Wallace, Dr. A., of Colchester,
235, 235 n. 2.
Wallace, A. R., 45, 92, 256;
dedication to, iii; 8. American
observations of, 1; theory of
Darwin and, xiv, xv, 8, 9;
publication of theory of Dar-
win and, 12-15; individual
differences the steps of evo-
lution for Darwin and, 265,
272-8; on Darwin, 14-15;
on protective resemblance,
108-5; on warning colours
of insects, 111-12; on sexes
of Ornithoptera croesus, 233
n. 1, 284; inscription in
memoir given by Bates to,
123 ; term mimicry restricted
by, 101, 145; memoir on
mimicry by, 132, 236, 238-9 ;
801
on female mimicry, 182-5,
138; on movements of mi-
metic Longicorns, 115; Dar-
win to, 104-5, 112, 129 n. 8,
133-4, 134 n. 1, 140, 255, 106,
the latter first published in
Section V.
Walsingham, Lord, 209.
Wanderings in the Great Forests
of Borneo, Beccari, 19.
Warner, C. D., 37.
Warning Colours, 110-12.
Wasps, as models, 114-16; Fos-
sors and, held by Asclepias
flowers, 225 n. 2.
Waterhouse, G. R., 202, 203 n. 1.
Watson and Cook, Janthanis
var. of Lim. archippus named
by, 212.
bitsy deh Miss Elizabeth,
241 n. 1.
weidermeyeri, Limenitis, 196.
Weir, J. Jenner, on distasteful-
ness of conspicuous larvae,
112; Darwin to, 112, 32, the
latter first published in ad-
dress I,
Weismann, A., 49 . 1; on the
non-transmission of acquired
characters, xv, 8, 33-42, 274-
5; Darwin to, 127.
Werner on colours, 111.
Westwood, J. O., Darwinism and,
15, 89, 90.
wheat, Darwin on limit to im-
rovement of, 48.
Whewell, Dr., and the Origin,
15, 89.
White, Adam, 214.
‘White Admiral’
164-5,
white moth, rejected by turkeys,
112, 112 n. 3.
eo Huxley and, 66-8,
butterfly,
Wilson, E. B., on resemblance
of Scyllaea to Sargassum, 107,
108; in to, 107, first pub-
lishedin Section V(see also 70).
Wollaston, 46.
802 INDEX
a at Darwin on the,
Wertaon i the Making, Arrhenius,
Wright, Dr., on Archaeopteryx,
Wright, Chauncey, defence of
Darwin by, 2, 31-2
Oxford ; Horace Hart, Printer to the University
York, Owen on ee
at (1881), 29
Zool. Soc. Proc., 107, 158.
Zoologica: N.Y. Zool. Soc., 110.
sc bs Erasmus Darwin, 3,4,
Zygaenidae, as mimics, 121.
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