More Letters of Charles Darwin Volume II

C >> Charles Darwin >> More Letters of Charles Darwin Volume II

Pages:
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49

Sorby read a paper to the Brit. Assoc., and he comes to the conclusion that
gneiss, etc., may be metamorphosed cleavage or strata; and I think he
admits much chemical segregation along the planes of division. (543/2.
"On the Microscopical Structure of Mica-schist:" "Brit. Ass. Rep." 1856,
page 78. See also Letters 540-542.) I quite subscribe to this view, and
should have been sorry to have been so utterly wrong, as I should have been
if foliation was identical with stratification.

I have been nowhere and seen no one, and really have no news of any kind to
tell you. I have been working away as usual, floating plants in salt water
inter alia, and confound them, they all sink pretty soon, but at very
different rates. Working hard at pigeons, etc., etc. By the way, I have
been astonished at the differences in the skeletons of domestic rabbits. I
showed some of the points to Waterhouse, and asked him whether he could
pretend that they were not as great as between species, and he answered,
"They are a great deal more." How very odd that no zoologist should ever
have thought it worth while to look to the real structure of varieties...

2.IX.VI. AGE OF THE WORLD, 1868-1877.

LETTER 544. TO J. CROLL.
Down, September 19th, 1868.

I hope that you will allow me to thank you for sending me your papers in
the "Phil. Magazine." (544/1. Croll published several papers in the
"Philosophical Magazine" between 1864 and the date of this letter (1868).)
I have never, I think, in my life been so deeply interested by any
geological discussion. I now first begin to see what a million means, and
I feel quite ashamed of myself at the silly way in which I have spoken of
millions of years. I was formerly a great believer in the power of the sea
in denudation, and this was perhaps natural, as most of my geological work
was done near sea-coasts and on islands. But it is a consolation to me to
reflect that as soon as I read Mr. Whitaker's paper (544/2. "On Subaerial
Denudation," and "On Cliffs and Escarpments of the Chalk and Lower Tertiary
Beds," "Geol. Mag." Volume IV., page 447, 1867.) on the escarpments of
England, and Ramsay (544/3. "Quart. Journ. Geol. Soc." Volume XVIII., page
185, 1862. "On the Glacial Origin of certain Lakes in Switzerland, the
Black Forest, Great Britain, Sweden, North America, and elsewhere.') and
Jukes' papers (544/4. "Quart. Journ. Geol. Soc." Volume XVIII., page 378,
1862. "On the Mode of Formation of some River-Valleys in the South of
Ireland."), I gave up in my own mind the case; but I never fully realised
the truth until reading your papers just received. How often I have
speculated in vain on the origin of the valleys in the chalk platform round
this place, but now all is clear. I thank you cordially for having cleared
so much mist from before my eyes.

LETTER 545. TO T. MELLARD READE.
Down, February 9th, 1877.

I am much obliged for your kind note, and the present of your essay. I
have read it with great interest, and the results are certainly most
surprising. (545/1. Presidential Address delivered by T. Mellard Reade
before the Liverpool Geological Society ("Proc. Liverpool Geol. Soc."
Volume III., pt. iii., page 211, 1877). See also "Examination of a
Calculation of the Age of the Earth, based upon the hypothesis of the
Permanence of Oceans and Continents." "Geol. Mag." Volume X., page 309,
1883.) It appears to me almost monstrous that Professor Tait should say
that the duration of the world has not exceeded ten million years. (545/2.
"Lecture on Some Recent Advances in Physical Science," by P.G. Tait,
London, 1876.) The argument which seems the most weighty in favour of the
belief that no great number of millions of years have elapsed since the
world was inhabited by living creatures is the rate at which the
temperature of the crust increases, and I wish that I could see this
argument answered.

LETTER 546. TO J. CROLL.
Down, August 9th, 1877.

I am much obliged for your essay, which I have read with the greatest
interest. With respect to the geological part, I have long wished to see
the evidence collected on the time required for denudation, and you have
done it admirably. (546/1. In a paper "On the Tidal Retardation Argument
for the Age of the Earth" ("Brit. Assoc. Report," 1876, page 88), Croll
reverts to the influence of subaerial denudation in altering the form of
the earth as an objection to the argument from tidal retardation. He had
previously dealt with this subject in "Climate and Time," Chapter XX.,
London, 1875.) I wish some one would in a like spirit compare the
thickness of sedimentary rocks with the quickest estimated rate of
deposition by a large river, and other such evidence. Your main argument
with respect to the sun seems to me very striking.

My son George desires me to thank you for his copy, and to say how much he
has been interested by it.

2.IX.VII. GEOLOGICAL ACTION OF EARTHWORMS, 1880-1882.

"My whole soul is absorbed with worms just at present." (From a letter to
Sir W. Thistleton-Dyer, November 26th, 1880.)

LETTER 547. TO T.H. FARRER (Lord Farrer).

(547/1. The five following letters, written shortly before and after the
publication of "The Formation of Vegetable Mould through the Action of
Worms," 1881, deal with questions connected with Mr. Darwin's work on the
habits and geological action of earthworms.)

Down, October 20th, 1880.

What a man you are to do thoroughly whatever you undertake to do! The
supply of specimens has been magnificent, and I have worked at them for a
day and a half. I find a very few well-rounded grains of brick in the
castings from over the gravel walk, and plenty over the hole in the field,
and over the Roman floor. (547/2. See "The Formation of Vegetable Mould,"
1881, pages 178 et seq. The Roman remains formed part of a villa
discovered at Abinger, Surrey. Excavations were carried out, under Lord
Farrer's direction, in a field adjoining the ground in which the Roman
villa was first found, and extended observations were made by Lord Farrer,
which led Mr. Darwin to conclude that a large part of the fine vegetable
mould covering the floor of the villa had been brought up from below by
worms.) You have done me the greatest possible service by making me more
cautious than I should otherwise have been--viz., by sending me the rubbish
from the road itself; in this rubbish I find very many particles, rounded
(I suppose) by having been crushed, angles knocked off, and somewhat rolled
about. But not a few of the particles may have passed through the bodies
of worms during the years since the road was laid down. I still think that
the fragments are ground in the gizzards of worms, which always contain
bits of stone; but I must try and get more evidence. I have to-day started
a pot with worms in very fine soil, with sharp fragments of hard tiles laid
on the surface, and hope to see in the course of time whether any of those
become rounded. I do not think that more specimens from Abinger would aid
me...

LETTER 548. TO G.J. ROMANES.
Down, March 7th.

I was quite mistaken about the "Gardeners' Chronicle;" in my index there
are only the few enclosed and quite insignificant references having any
relation to the minds of animals. When I returned to my work, I found that
I had nearly completed my statement of facts about worms plugging up their
burrows with leaves (548/1. Chapter II., of "The Formation of Vegetable
Mould through the Action of Worms," 1881, contains a discussion on the
intelligence shown by worms in the manner of plugging up their burrows with
leaves (pages 78 et seq.).), etc., etc., so I waited until I had naturally
to draw up a few concluding remarks. I hope that it will not bore you to
read the few accompanying pages, and in the middle you will find a few
sentences with a sort of definition of, or rather discussion on,
intelligence. I am altogether dissatisfied with it. I tried to observe
what passed in my own mind when I did the work of a worm. If I come across
a professed metaphysician, I will ask him to give me a more technical
definition, with a few big words about the abstract, the concrete, the
absolute, and the infinite; but seriously, I should be grateful for any
suggestions, for it will hardly do to assume that every fool knows what
"intelligent" means. (548/2. "Mr. Romanes, who has specially studied the
minds of animals, believes that we can safely infer intelligence only when
we see an individual profiting by its own experience...Now, if worms try to
drag objects into their burrows, first in one way and then in another,
until they at last succeed, they profit, at least in each particular
instance, by experience" ("The Formation of Vegetable Mould," 1881, page
95).) You will understand that the MS. is only the first rough copy, and
will need much correction. Please return it, for I have no other copy--
only a few memoranda. When I think how it has bothered me to know what I
mean by "intelligent," I am sorry for you in your great work on the minds
of animals.

I daresay that I shall have to alter wholly the MS.

LETTER 549. TO FRANCIS GALTON.
Down, March 8th [1881].

Very many thanks for your note. I have been observing the [worm] tracks on
my walks for several months, and they occur (or can be seen) only after
heavy rain. As I know that worms which are going to die (generally from
the parasitic larva of a fly) always come out of their burrows, I have
looked out during these months, and have usually found in the morning only
from one to three or four along the whole length of my walks. On the other
hand, I remember having in former years seen scores or hundreds of dead
worms after heavy rain. (549/1. "After heavy rain succeeding dry weather,
an astonishing number of dead worms may sometimes be seen lying on the
ground. Mr. Galton informs me that on one occasion (March, 1881), the dead
worms averaged one for every two-and-a-half paces in length on a walk in
Hyde Park, four paces in width" (loc. cit., page 14).) I cannot possibly
believe that worms are drowned in the course of even three or four days'
immersion; and I am inclined to conclude that the death of sickly (probably
with parasites) worms is thus hastened. I will add a few words to what I
have said about these tracks. Occasionally worms suffer from epidemics (of
what nature I know not) and die by the million on the surface of the
ground. Your ruby paper answers capitally, but I suspect that it is only
for dimming the light, and I know not how to illuminate worms by the same
intensity of light, and yet of a colour which permits the actinic rays to
pass. I have tried drawing triangles of damp paper through a small
cylindrical hole, as you suggested, and I can discover no source of error.
(549/2. Triangles of paper were used in experiments to test the
intelligence of worms (loc. cit., page 83).) Nevertheless, I am becoming
more doubtful about the intelligence of worms. The worst job is that they
will do their work in a slovenly manner when kept in pots (549/3. Loc.
cit., page 75.), and I am beyond measure perplexed to judge how far such
observations are trustworthy.

LETTER 550. TO E. RAY LANKESTER.

(550/1. Mr. Lankester had written October 11th, 1881, to thank Mr. Darwin
for the present of the Earthworm book. He asks whether Darwin knows of
"any experiments on the influence of sea-water on earthworms. I have
assumed that it is fatal to them. But there is a littoral species
(Pontodrilus of Perrier) found at Marseilles." Lankester adds, "It is a
great pleasure and source of pride to me to see my drawing of the
earthworm's alimentary canal figuring in your pages."

Down, October 13th [1881].

I have been much pleased and interested by your note. I never actually
tried sea-water, but I was very fond of angling when a boy, and as I could
not bear to see the worms wriggling on the hook, I dipped them always first
in salt water, and this killed them very quickly. I remember, though not
very distinctly, seeing several earthworms dead on the beach close to where
a little brook entered, and I assumed that they had been brought down by
the brook, killed by the sea-water, and cast on shore. With your skill and
great knowledge, I have no doubt that you will make out much new about the
anatomy of worms, whenever you take up the subject again.

LETTER 551. TO J.H. GILBERT.
Down, January, 12th, 1882.

I have been much interested by your letter, for which I thank you heartily.
There was not the least cause for you to apologise for not having written
sooner, for I attributed it to the right cause, i.e. your hands being full
of work.

Your statement about the quantity of nitrogen in the collected castings is
most curious, and much exceeds what I should have expected. In lately
reading one of your and Mr. Lawes' great papers in the "Philosophical
Transactions" (551/1. The first Report on "Agricultural, Botanical, and
Chemical Results of Experiments on the Mixed Herbage of Permanent
Grassland, conducted for many years in succession on the same land," was
published in the "Philosophical Transactions of the Royal Society" in 1880,
the second paper appeared in the "Phil. Trans." for 1882, and the third in
the "Phil. Trans." of 1900, Volume 192, page 139.) (the value and
importance of which cannot, in my opinion, be exaggerated) I was struck
with the similarity of your soil with that near here; and anything observed
here would apply to your land. Unfortunately I have never made deep
sections in this neighbourhood, so as to see how deep the worms burrow,
except in one spot, and here there had been left on the surface of the
chalk a little very fine ferruginous sand, probably of Tertiary age; into
this the worms had burrowed to a depth of 55 and 61 inches. I have never
seen here red castings on the surface, but it seems possible (from what I
have observed with reddish sand) that much of the red colour of the
underlying clay would be discharged in passing through the intestinal
canal.

Worms usually work near the surface, but I have noticed that at certain
seasons pale-coloured earth is brought up from beneath the outlying
blackish mould on my lawn; but from what depth I cannot say. That some
must be brought up from a depth of four or five or six feet is certain, as
the worms retire to this depth during very dry and very cold weather. As
worms devour greedily raw flesh and dead worms, they could devour dead
larvae, eggs, etc., etc., in the soil, and thus they might locally add to
the amount of nitrogen in the soil, though not of course if the whole
country is considered. I saw in your paper something about the difference
in the amount of nitrogen at different depths in the superficial mould, and
here worms may have played a part. I wish that the problem had been before
me when observing, as possibly I might have thrown some little light on it,
which would have pleased me greatly.

2.IX.VIII. MISCELLANEOUS, 1846-1878.

(552/1. The following four letters refer to questions connected with the
origin of coal.)

LETTER 552. TO J.D. HOOKER.
Down, May [1846].

I am delighted that you are in the field, geologising or palaeontologising.
I beg you to read the two Rogers' account of the Coal-fields of N. America;
in my opinion they are eminently instructive and suggestive. (552/1. "On
the Physical Structure of the Appalachian Chain," by W.B. and H.D. Rogers.
Boston, 1843. See also "Geology of Pennsylvania," by H.D. Rogers. 4
volumes. London and Philadelphia, 1843.) I can lend you their resume of
their own labours, and, indeed, I do not know that their work is yet
published in full. L. Horner gives a capital balance of difficulties on
the Coal-theory in his last Anniversary Address, which, if you have not
read, will, I think, interest you. (552/2. "Quart. Journ. Geol. Soc."
Volume II., 1846, page 170.) In a paper just read an author (552/3. "On
the Remarkable Fossil Trees lately discovered near St. Helen's." By E.W.
Binney. "Phil. Mag." Volume XXIV., page 165, 1844. On page 173 the author
writes: "The Stigmaria or Sigillaria, whichever name is to be retained...
was a tree that undoubtedly grew in water.") throws out the idea that the
Sigillaria was an aquatic plant (552/4. See "Life and Letters," I., pages
356 et seq.)--I suppose a Cycad-Conifer with the habits of the mangrove.
From simple geological reasoning I have for some time been led to suspect
that the great (and great and difficult it is) problem of the Coal would be
solved on the theory of the upright plants having been aquatic. But even
on such, I presume improbable notion, there are, as it strikes me, immense
difficulties, and none greater than the width of the coal-fields. On what
kind of coast or land could the plants have lived? It is a grand problem,
and I trust you will grapple with it. I shall like much to have some
discussion with you. When will you come here again? I am very sorry to
infer from your letter that your sister has been ill.

LETTER 553. TO J.D. HOOKER.
[June 2nd, 1847.]

I received your letter the other day, full of curious facts, almost all new
to me, on the coal-question. (553/1. Sir Joseph Hooker deals with the
formation of coal in his classical paper "On the Vegetation of the
Carboniferous Period, as compared with that of the Present Day." "Mem.
Geol. Surv. Great Britain," Volume II., pt. ii., 1848.) I will bring your
note to Oxford (553/2. The British Association met at Oxford in 1847.),
and then we will talk it over. I feel pretty sure that some of your purely
geological difficulties are easily solvable, and I can, I think, throw a
very little light on the shell difficulty. Pray put no stress in your mind
about the alternate, neatly divided, strata of sandstone and shale, etc. I
feel the same sort of interest in the coal question as a man does watching
two good players at play, he knowing little or nothing of the game. I
confess your last letter (and this you will think very strange) has almost
raised Binney's notion (an old, growing hobby-horse of mine) to the dignity
of an hypothesis (553/3. Binney suggested that the Coal-plants grew in
salt water. (See Letters 102, 552.) Recent investigations have shown that
several of the plants of the Coal period possessed certain anatomical
peculiarities, which indicate xerophytic characteristics, and lend support
to the view that some at least of the plants grew in seashore swamps.),
though very far yet below the promotion of being properly called a theory.

I will bring the remainder of my species-sketch to Oxford to go over your
remarks. I have lately been getting a good many rich facts. I saw the
poor old Dean of Manchester (553/4. Dean Herbert.) on Friday, and he
received me very kindly. He looked dreadfully ill, and about an hour
afterwards died! I am most sincerely sorry for it.

LETTER 554. TO J.D. HOOKER.
[May 12th, 1847.]

I cannot resist thanking you for your most kind note. Pray do not think
that I was annoyed by your letter. I perceived that you had been thinking
with animation, and accordingly expressed yourself strongly, and so I
understood it. Forefend me from a man who weighs every expression with
Scotch prudence. I heartily wish you all success in your noble problem,
and I shall be very curious to have some talk with you and hear your
ultimatum. (554/1. The above paragraph was published in "Life and
Letters," I., page 359.) I do really think, after Binney's pamphlet
(554/2. "On the Origin of Coal," "Mem. Lit. Phil. Soc." Manchester Volume
VIII., page 148, 1848.), it will be worth your while to array your facts
and ideas against an aquatic origin of the coal, though I do not know
whether you object to freshwater. I am sure I have read somewhere of the
cones of Lepidodendron being found round the stump of a tree, or am I
confusing something else? How interesting all rooted--better, it seems
from what you say, than upright--specimens become.

I wish Ehrenberg would undertake a microscopical hunt for infusoria in the
underclay and shales; it might reveal something. Would a comparison of the
ashes of terrestrial peat and coal give any clue? (554/3. In an article
by M. F. Rigaud on "La Formation de la Houille," published in the "Revue
Scientifique," Volume II., page 385, 1894, the author lays stress on the
absence of certain elements in the ash of coals, which ought to be present,
on the assumption that the carbon has been derived from plant tissues. If
coal consists of altered vegetable debris, we ought to find a certain
amount of alkalies and phosphoric acid in its ash. Had such substances
ever been present, it is difficult to understand how they could all have
been removed by the solvent action of water. (Rigaud's views are given at
greater length in an article on the "Structure and Formation of Coal,"
"Science Progress," Volume II., pages 355 and 431, 1895.)) Peat ashes are
good manure, and coal ashes, except mechanically, I believe are of little
use. Does this indicate that the soluble salts have been washed out? i.e.,
if they are NOT present. I go up to Geological Council to-day--so
farewell.

(554/4. In a letter to Sir Joseph Hooker, October 6th, 1847, Mr. Darwin,
in referring to the origin of Coal, wrote: "...I sometimes think it could
not have been formed at all. Old Sir Anthony Carlisle once said to me
gravely that he supposed Megatherium and such cattle were just sent down
from heaven to see whether the earth would support them, and I suppose the
coal was rained down to puzzle mortals. You must work the coal well in
India.")

LETTER 555. TO J.D. HOOKER.
Down, May 22nd, 1860.

Lyell tells me that Binney has published in Proceedings of Manchester
Society a paper trying to show that Coal plants must have grown in very
marine marshes. (555/1. "On the Origin of Coal," by E.W. Binney, "Mem.
Lit. Phil. Soc. Manchester," Volume VIII., 1848, page 148. Binney examines
the evidence on which dry land has been inferred to exist during the
formation of the Coal Measures, and comes to the conclusion that the land
was covered by water, confirming Brongniart's opinion that Sigillaria was
an aquatic plant. He believes the Sigillaria "grew in water, on the
deposits where it is now discovered, and that it is the plant which in a
great measure contributed to the formation of our valuable beds of coal."
(Loc. cit., page 193.)) Do you remember how savage you were long years ago
at my broaching such a conjecture?

LETTER 556. TO L. HORNER.
Down [1846?].

I am truly pleased at your approval of my book (556/1. "Geological
Observations on South America," London, 1846.): it was very kind of you
taking the trouble to tell me so. I long hesitated whether I would publish
it or not, and now that I have done so at a good cost of trouble, it is
indeed highly satisfactory to think that my labour has not been quite
thrown away.

I entirely acquiesce in your criticism on my calling the Pampean formation
"recent" (556/2. "We must, therefore, conclude that the Pampean formation
belongs, in the ordinary geological sense of the word, to the Recent
Period." ("Geol. Obs." page 101).); Pleistocene would have been far
better. I object, however, altogether on principle (whether I have always
followed my principle is another question) to designate any epoch after
man. It breaks through all principles of classification to take one
mammifer as an epoch. And this is presupposing we know something of the
introduction of man: how few years ago all beds earlier than the
Pleistocene were characterised as being before the monkey epoch. It
appears to me that it may often be convenient to speak of an Historical or
Human deposit in the same way as we speak of an Elephant bed, but that to
apply it to an epoch is unsound.

I have expressed myself very ill, and I am not very sure that my notions
are very clear on this subject, except that I know that I have often been
made wroth (even by Lyell) at the confidence with which people speak of the
introduction of man, as if they had seen him walk on the stage, and as if,
in a geological chronological sense, it was more important than the entry
of any other mammifer.

You ask me to do a most puzzling thing, to point out what is newest in my
volume, and I found myself incapable of doing almost the same for Lyell.
My mind goes from point to point without deciding: what has interested
oneself or given most trouble is, perhaps quite falsely, thought newest.
The elevation of the land is perhaps more carefully treated than any other
subject, but it cannot, of course, be called new. I have made out a sort
of index, which will not take you a couple of minutes to skim over, and
then you will perhaps judge what seems newest. The summary at the end of
the book would also serve same purpose.

I do not know where E. de B. [Elie de Beaumont] has lately put forth on the
recent elevation of the Cordillera. He "rapported" favourably on
d'Orbigny, who in late times fires off a most Royal salute; every volcano
bursting forth in the Andes at the same time with their elevation, the
debacle thus caused depositing all the Pampean mud and all the Patagonian
shingle! Is not this making Geology nice and simple for beginners?