More Letters of Charles Darwin Volume I

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LETTER 259. TO J.D. HOOKER.
Down, June 28th, 1873.

I write a line to wish you good-bye, as I hear you are off on Wednesday,
and to thank you for the Dionoea, but I cannot make the little creature
grow well. I have this day read Bentham's last address, and must express
my admiration of it. (259/1. Presidential address to the Linnean Society,
read May 24th, 1873.) Perhaps I ought not to do so, as he fairly crushes
me with honour.

I am delighted to see how exactly I agree with him on affinities, and
especially on extinct forms as illustrated by his flat-topped tree.
(259/2. See page 15 of separate copy: "We should then have the present
races represented by the countless branchlets forming the flat-topped
summit" of a genealogical tree, in which "all we can do is to map out the
summit as it were from a bird's-eye view, and under each cluster, or
cluster of clusters, to place as the common trunk an imaginary type of a
genus, order, or class according to the depth to which we would go.") My
recent work leads me to differ from him on one point--viz., on the
separation of the sexes. (259/3. On the question of sexuality, see page
10 of Bentham's address. On the back of Mr. Darwin's copy he has written:
"As long as lowest organisms free--sexes separated: as soon as they become
attached, to prevent sterility sexes united--reseparated as means of
fertilisation, adapted [?] for distant [?] organisms,--in the case of
animals by their senses and voluntary movements,--with plants the aid of
insects and wind, the latter always existed, and long retained." The two
words marked [?] are doubtful. The introduction of freedom or
attachedness, as a factor in the problem also occurs in "Cross and Self-
fertilisation," page 462. I strongly suspect that sexes were primordially
in distinct individuals; then became commonly united in the same
individual, and then in a host of animals and some few plants became again
separated. Do ask Bentham to send a copy of his address to "Dr. H. Muller,
Lippstadt, Prussia," as I am sure it will please him GREATLY.

...When in France write me a line and tell me how you get on, and how
Huxley is; but do not do so if you feel idle, and writing bothers you.

LETTER 260. TO R. MELDOLA.

(260/1. This letter, with others from Darwin to Meldola, is published in
"Charles Darwin and the Theory of Natural Selection," by E.B. Poulton,
pages 199 et seq., London, 1896.)

Southampton, August 13th, 1873.

I am much obliged for your present, which no doubt I shall find at Down on
my return home. I am sorry to say that I cannot answer your question; nor
do I believe that you could find it anywhere even approximately answered.
It is very difficult or impossible to define what is meant by a 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. I wish I could have given you any answer.

LETTER 261. TO E.S. MORSE.
[Undated.]

I must have the pleasure of thanking you for your kindness in sending me
your essay on the Brachiopoda. (261/1. "The Brachiopoda, a Division of
Annelida," "Amer. Assoc. Proc." Volume XIX., page 272, 1870, and "Annals
and Mag. Nat. Hist." Volume VI., page 267, 1870.) I have just read it with
the greatest interest, and you seem to me (though I am not a competent
judge) to make out with remarkable clearness an extremely strong case.
What a wonderful change it is to an old naturalist to have to look at these
"shells" as "worms"; but, as you truly say, as far as external appearance
is concerned, the case is not more wonderful than that of cirripedes. I
have also been particularly interested by your remarks on the Geological
Record, and on the lower and older forms in each great class not having
been probably protected by calcareous valves or a shell.

P.S.--Your woodcut of Lingula is most skilfully introduced to compel one to
see its likeness to an annelid.

LETTER 262. TO H. SPENCER.

(262/1. Mr. Spencer's book "The Study of Sociology," 1873, was published
in the "Contemporary Review" in instalments between May 1872 and October
1873.)

October 31st [1873].

I am glad to receive to-day an advertisement of your book. I have been
wonderfully interested by the articles in the "Contemporary." Those were
splendid hits about the Prince of Wales and Gladstone. (262/2. See "The
Study of Sociology," page 392. Mr. Gladstone, in protest against some
words of Mr. Spencer, had said that the appearance of great men "in great
crises of human history" were events so striking "that men would be liable
to term them providential in a pre-scientific age." On this Mr. Spencer
remarks that "in common with the ancient Greek Mr. Gladstone regards as
irreligious any explanation of Nature which dispenses with immediate Divine
superintendence." And as an instance of the partnership "between the ideas
of natural causation and of providential interference," he instances a case
where a prince "gained popularity by outliving certain abnormal changes in
his blood," and where "on the occasion of his recovery providential aid and
natural causation were unitedly recognised by a thanksgiving to God and a
baronetcy to the doctor." The passage on Toryism is on page 395, where Mr.
Spencer, with his accustomed tolerance, writes: "The desirable thing is
that a growth of ideas and feelings tending to produce modification shall
be joined with a continuance of ideas and feelings tending to preserve
stability." And from this point of view he concludes it to be very
desirable that "one in Mr. Gladstone's position should think as he does."
The matter is further discussed in the notes to Chapter XVI., page 423.) I
never before read a good defence of Toryism. In one place (but I cannot
for the life of me recollect where or what it exactly was) I thought that
you would have profited by my principle (i.e. if you do not reject it)
given in my "Descent of Man," that new characters which appear late in life
are those which are transmitted to the same sex alone. I have advanced
some pretty strong evidence, and the principle is of great importance in
relation to secondary sexual likenesses. (262/3. This refers to Mr.
Spencer's discussion of the evolution of the mental traits characteristic
of women. At page 377 he points out the importance of the limitation of
heredity by sex in this relation. A striking generalisation on this
question is given in the "Descent of Man," Edition I., Volume II., page
285: that when the adult male differs from the adult female, he differs in
the same way from the young of both sexes. Can this law be applied in the
case in which the adult female possesses characters not possessed by the
male: for instance, the high degree of intuitive power of reading the
mental states of others and of concealing her own--characters which Mr.
Spencer shows to be accounted for by the relations between the husband and
wife in a state of savagery. If so, the man should resemble "the young of
both sexes" in the absence of these special qualities. This seems to be
the case with some masculine characteristics, and childishness of man is
not without recognition among women: for instance, by Dolly Winthrop in
"Silas Marner," who is content with bread for herself, but bakes cake for
children and men, whose "stomichs are made so comical, they want a change--
they do, I know, God help 'em.") I have applied it to man and woman, and
possibly it was here that I thought that you would have profited by the
doctrine. I fear that this note will be almost illegible, but I am very
tired.

LETTER 263. G.J. ROMANES TO CHARLES DARWIN.

(263/1. This is, we believe, the first letter addressed by the late Mr.
Romanes to Mr. Darwin. It was put away with another on the same subject,
and inscribed "Romanes on Abortion, with my answer (very important)." Mr.
Darwin's answer given below is printed from his rough draft, which is in
places barely decipherable. On the subject of these letters consult
Romanes, "Darwin and after Darwin," Volume II., page 99, 1895.)

Dunskaith, Parkhill, Ross-shire, July 10th, 1874.

Knowing that you do not dissuade the more attentive of your readers from
communicating directly to yourself any ideas they may have upon subjects
connected with your writings, I take the liberty of sending the enclosed
copy of a letter, which I have recently addressed to Mr. Herbert Spencer.
You will perceive that the subject dealt with is the same as that to which
a letter of mine in last week's "Nature" [July 2nd, page 164] refers--viz.,
"Disuse as a Reducing Cause in Species." In submitting this more detailed
exposition of my views to your consideration, I should like to state again
what I stated in "Nature" some weeks ago, viz., that in propounding the
cessation of selection as a reducing cause, I do not suppose that I am
suggesting anything which has not occurred to you already. Not only is
this principle embodied in the theory set forth in the article on
Rudimentary Organs ("Nature," Volume IX.); but it is more than once hinted
at in the "Origin," in the passages where rudimentary organs are said to be
more variable than others, because no longer under the restraining
influence of Natural Selection. And still more distinctly is this
principle recognised in page 120.

Thus, in sending you the enclosed letter, I do not imagine that I am
bringing any novel suggestions under your notice. As I see that you have
already applied the principle in question to the case of artificially-bred
structures, I cannot but infer that you have pondered it in connection with
naturally-bred structures. What objection, however, you can have seen to
this principle in this latter connection, I am unable to divine; and so I
think the best course for me to pursue is the one I adopt--viz., to send
you my considerations in full.

In the absence of express information, the most natural inference is that
the reason you refuse to entertain the principle in question, is because
you show the backward tendency of indiscriminate variability [to be]
inadequate to contend with the conservative tendency of long inheritance.
The converse of this is expressed in the words "That the struggle between
Natural Selection on the one hand, and the tendency to reversion and
variability on the other hand, will in the course of time cease; and that
the most abnormally developed organs may be made constant, I see no reason
to doubt" ("Origin," page 121). Certainly not, if, as I doubt not, the
word "constant" is intended to bear a relative signification; but to say
that constancy can ever become absolute--i.e., that any term of inheritance
could secure to an organ a total immunity from the smallest amount of
spontaneous variability--to say this would be unwarrantable. Suppose, for
instance, that for some reason or other a further increase in the size of a
bat's wing should now suddenly become highly beneficial to that animal: we
can scarcely suppose that variations would not be forthcoming for Natural
Selection to seize upon (unless the limit of possible size has now been
reached, which is an altogether distinct matter). And if we suppose that
minute variations on the side of increase are thus even now occasionally
taking place, much more is it probable that similar variations on the side
of decrease are now taking place--i.e., that if the conservative influence
of Natural Selection were removed for a long period of time, more
variations would ensue below the present size of bat's wings, than above
it. To this it may be added, that when the influence of "speedy selection"
is removed, it seems in itself highly probable that the structure would,
for this reason, become more variable, for the only reason why it ever
ceased to be variable (i.e., after attaining its maximum size), was because
of the influence of selection constantly destroying those individuals in
which a tendency to vary occurred. When, therefore, this force
antagonistic to variability was removed, it seems highly probable that the
latter principle would again begin to assert itself, and this in a
cumulative manner. Those individuals in which a tendency to vary occurred
being no longer cut off, they would have as good a chance of leaving
progeny to inherit their fluctuating disposition as would their more
inflexible companions.

LETTER 264. TO G.J. ROMANES.
July 16th, 1874.

I am much obliged for your kind and long communication, which I have read
with great interest, as well as your articles in "Nature." The subject
seems to me as important and interesting as it is difficult. I am much out
of health, and working very hard on a very different subject, so thus I
cannot give your remarks the attention which they deserve. I will,
however, keep your letter for some later time, when I may again take up the
subject. Your letter makes it clearer to me than it ever was before, how a
part or organ which has already begun from any cause to decrease, will go
on decreasing through so-called spontaneous variability, with
intercrossing; for under such circumstances it is very unlikely that there
should be variation in the direction of increase beyond the average size,
and no reason why there should not be variations of decrease. I think this
expresses your view. I had intended this summer subjecting plants to
[illegible] conditions, and observing the effects on variation; but the
work would be very laborious, yet I am inclined to think it will be
hereafter worth the labour.

LETTER 265. TO T. MEEHAN.
Down, October 9th, 1874.

I am glad that you are attending to the colours of dioecious 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. Some thirty years ago I began to investigate the little purple
flowers in the centre of the umbels of the carrot. I suppose my memory is
wrong, but it tells me that these flowers are female, and I think that I
once got a seed from one of them; but my memory may be quite wrong. I hope
that you will continue your interesting researches.

LETTER 266. TO G. JAGER.
Down, February 3rd, 1875.

I received this morning a copy of your work "Contra Wigand," either from
yourself or from your publisher, and I am greatly obliged for it. (266/1.
Jager's "In Sachen Darwins insbesondere contra Wigand" (Stuttgart, 1874) is
directed against A. Wigand's "Der Darwinismus und die Naturforschung
Newtons und Cuviers" (Brunswick, 1874).) I had, however, before bought a
copy, and have sent the new one to our best library, that of the Royal
Society. As I am a very poor german scholar, I have as yet read only about
forty pages; but these have interested me in the highest degree. Your
remarks on fixed and variable species deserve the greatest attention; but I
am not at present quite convinced that there are such independent of the
conditions to which they are subjected. I think you have done great
service to the principle of evolution, which we both support, by publishing
this work. I am the more glad to read it as I had not time to read
Wigand's great and tedious volume.

LETTER 267. TO CHAUNCEY WRIGHT.
Down, March 13th, 1875.

I write to-day so that there shall be no delay this time in thanking you
for your interesting and long letter received this morning. I am sure that
you will excuse brevity when I tell you that I am half-killing myself in
trying to get a book ready for the press. (267/1. The MS. of
"Insectivorous Plants" was got ready for press in March, 1875. Darwin
seems to have been more than usually oppressed by the work.) I quite agree
with what you say about advantages of various degrees of importance being
co-selected (267/2. Mr. Chauncey Wright wrote (February 24th, 1875): "The
inquiry as to which of several real uses is the one through which Natural
Selection has acted...has for several years seemed to me a somewhat less
important question than it seemed formerly, and still appears to most
thinkers on the subject...The uses of the rattling of the rattlesnake as a
protection by warning its enemies and as a sexual call are not rival uses;
neither are the high-reaching and the far-seeing uses of the giraffe's neck
'rivals.'"), and aided by the effects of use, etc. The subject seems to me
well worth further development. I do not think I have anywhere noticed the
use of the eyebrows, but have long known that they protected the eyes from
sweat. During the voyage of the "Beagle" one of the men ascended a lofty
hill during a very hot day. He had small eyebrows, and his eyes became
fearfully inflamed from the sweat running into them. The Portuguese
inhabitants were familiar with this evil. I think you allude to the
transverse furrows on the forehead as a protection against sweat; but
remember that these incessantly appear on the foreheads of baboons.

P.S.--I have been greatly pleased by the notices in the "Nation."

LETTER 268. TO A. WEISMANN.
Down, May 1st, 1875.

I did not receive your essay for some days after your very kind letter, and
I read german so slowly that I have only just finished it. (268/1.
"Studien zur Descendenz-Theorie" I. "Ueber den Saison-Dimorphismus," 1875.
The fact was previously known that two forms of the genus Vanessa which had
been considered to be distinct species are only SEASONAL forms of the same
species--one appearing in spring, the other in summer. This remarkable
relationship forms the subject of the essay.) Your work has interested me
greatly, and your conclusions seem well established. I have long felt much
curiosity about season-dimorphism, but never could form any theory on the
subject. Undoubtedly your view is very important, as bearing on the
general question of variability. When I wrote the "Origin" I could not
find any facts which proved the direct action of climate and other external
conditions. I long ago thought that the time would soon come when the
causes of variation would be fully discussed, and no one has done so much
as you in this important subject. The recent evidence of the difference
between birds of the same species in the N. and S. United States well shows
the power of climate. The two sexes of some few birds are there
differently modified by climate, and I have introduced this fact in the
last edition of my "Descent of Man." (268/2. "Descent of Man," Edition
II. (in one volume), page 423. Allen showed that many species of birds are
more strongly coloured in the south of the United States, and that
sometimes one sex is more affected than the other. It is this last point
that bears on Weismann's remarks (loc. cit., pages 44, 45) on Pieris napi.
The males of the alpine-boreal form bryoniae hardly differ from those of
the German form (var. vernalis), while the females are strikingly
different. Thus the character of secondary sexual differences is
determined by climate.) I am, therefore, fully prepared to admit the
justness of your criticism on sexual selection of lepidoptera; but
considering the display of their beauty, I am not yet inclined to think
that I am altogether in error.

What you say about reversion (268/3. For instance, the fact that reversion
to the primary winter-form may be produced by the disturbing effect of high
temperature (page 7).) being excited by various causes, agrees with what I
concluded with respect to the remarkable effects of crossing two breeds:
namely, that anything which disturbs the constitution leads to reversion,
or, as I put the case under my hypothesis of pangenesis, gives a good
chance of latent gemmules developing. Your essay, in my opinion, is an
admirable one, and I thank you for the interest which it has afforded me.

P.S. I find that there are several points, which I have forgotten. Mr.
Jenner Weir has not published anything more about caterpillars, but I have
written to him, asking him whether he has tried any more experiments, and
will keep back this letter till I receive his answer. Mr. Riley of the
United States supports Mr. Weir, and you will find reference to him and
other papers at page 426 of the new and much-corrected edition of my
"Descent of Man." As I have a duplicate copy of Volume I. (I believe
Volume II. is not yet published in german) I send it to you by this post.
Mr. Belt, in his travels in Nicaragua, gives several striking cases of
conspicuously coloured animals (but not caterpillars) which are distasteful
to birds of prey: he is an excellent observer, and his book, "The
Naturalist in Nicaragua," very interesting.

I am very much obliged for your photograph, which I am particularly glad to
possess, and I send mine in return.

I see you allude to Hilgendorf's statements, which I was sorry to see
disputed by some good German observer. Mr. Hyatt, an excellent
palaeontologist of the United States, visited the place, and likewise
assured me that Hilgendorf was quite mistaken. (268/4. See Letters 252-
7.)

I am grieved to hear that your eyesight still continues bad, but anyhow it
has forced your excellent work in your last essay.

May 4th. Here is what Mr. Weir says:--

"In reply to your inquiry of Saturday, I regret that I have little to add
to my two communications to the 'Entomological Society Transactions.'

"I repeated the experiments with gaudy caterpillars for years, and always
with the same results: not on a single occasion did I find richly
coloured, conspicuous larvae eaten by birds. It was more remarkable to
observe that the birds paid not the slightest attention to gaudy
caterpillars, not even when in motion,--the experiments so thoroughly
satisfied my mind that I have now given up making them."

LETTER 269. TO LAWSON TAIT.

(269/1. The late Mr. Lawson Tait wrote to Mr. Darwin (June 2nd, 1875): "I
am watching a lot of my mice from whom I removed the tails at birth, and I
am coming to the conclusion that the essential use of the tail there is as
a recording organ--that is, they record in their memories the corners they
turn and the height of the holes they pass through by touching them with
their tails." Mr. Darwin was interested in the idea because "some German
sneered at Natural Selection and instanced the tails of mice.")

June 11th, 1875.

It has just occurred to me to look at the "Origin of Species" (Edition VI.,
page 170), and it is certain that Bronn, in the appended chapter to his
translation of my book into german, did advance ears and tail of various
species of mice as a difficulty opposed to Natural Selection. I answered
with respect to ears by alluding to Schobl's curious paper (I forget when
published) (269/2. J. Schobl, "Das aussere Ohr der Mause als wichtiges
Tastorgan." "Archiv. Mik. Anat." VII., 1871, page 260.) on the hairs of
the ears being sensitive and provided with nerves. I presume he made fine
sections: if you are accustomed to such histological work, would it not be
worth while to examine hairs of tail of mice? At page 189 I quote Henslow
(confirmed by Gunther) on Mus messorius (and other species?) using tail as
prehensile organ.

Dr. Kane in his account of the second Grinnell Expedition says that the
Esquimaux in severe weather carry a fox-tail tied to the neck, which they
use as a respirator by holding the tip of the tail between their teeth.
(269/3. The fact is stated in Volume II., page 24, of E.K. Kane's "Arctic
Explorations: The Second Grinnell Expedition in Search of Sir John
Franklin." Philadelphia, 1856.)

He says also that he found a frozen fox curled up with his nose buried in
his tail.

N.B. It is just possible that the latter fact is stated by M'Clintock, not
by Dr. Kane.

(269/4. The final passage is a postscript by Mr. W.E. Darwin bearing on
Mr. Lawson Tait's idea of the respirator function of the fox's tail.)

LETTER 270. TO G.J. ROMANES.
Down, July 12th, 1875.

I am correcting a second edition of "Variation under Domestication," and
find that I must do it pretty fully. Therefore I give a short abstract of
potato graft-hybrids, and I want to know whether I did not send you a
reference about beet. Did you look to this, and can you tell me anything
about it?

I hope with all my heart that you are getting on pretty well with your
experiments.

I have been led to think a good deal on the subject, and am convinced of
its high importance, though it will take years of hammering before
physiologists will admit that the sexual organs only collect the generative
elements.

The edition will be published in November, and then you will see all that I
have collected, but I believe that you gave all the more important cases.
The case of vine in "Gardeners' Chronicle," which I sent you, I think may
only be a bud-variation not due to grafting. I have heard indirectly of
your splendid success with nerves of medusae. We have been at Abinger Hall
for a month for rest, which I much required, and I saw there the cut-leaved
vine which seems splendid for graft hybridism.