More Letters of Charles Darwin Volume II

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LETTER 750. TO A. STEPHEN WILSON.

(750/1. The following letters refer to two forms of wheat cultivated in
Russia under the names Kubanka and Saxonka, which had been sent to Mr.
Darwin by Dr. Asher from Samara, and were placed in the hands of Mr.
Wilson that he might test the belief prevalent in Russia that Kubanka
"grown repeatedly on inferior soil," assumes "the form of Saxonka." Mr.
Wilson's paper of 1880 gives the results of his inquiry. He concludes
(basing his views partly on analogous cases and partly on his study of
the Russian wheats) that the supposed transformation is explicable in
chief part by the greater fertility of the Saxonka wheat leading to
extermination of the other form. According to Mr. Wilson, therefore,
the Saxonka survivors are incorrectly assumed to be the result of the
conversion of one form into the other.)

Down, April 24th, 1878.

I send you herewith some specimens which may perhaps interest you, as
you have so carefully studied the varieties of wheat. Anyhow, they are
of no use to me, as I have neither knowledge nor time sufficient. They
were sent me by the Governor of the Province of Samara, in Russia, at
the request of Dr. Asher (son of the great Berlin publisher) who farmed
for some years in the province. The specimen marked Kubanka is a very
valuable kind, but which keeps true only when cultivated in fresh
steppe-land in Samara, and in Saratoff. After two years it degenerates
into the variety Saxonica, or its synonym Ghirca. The latter alone is
imported into this country. Dr. Asher says that it is universally
known, and he has himself witnessed the fact, that if grain of the
Kubanka is sown in the same steppe-land for more than two years it
changes into Saxonica. He has seen a field with parts still Kubanka and
the remainder Saxonica. On this account the Government, in letting
steppe-land, contracts that after two years wheat must not be sown until
an interval of eight years. The ears of the two kinds appear different,
as you will see, but the chief difference is in the quality of the
grains. Dr. Asher has witnessed sales of equal weights of Kubanka and
Saxonica grain, and the price of the former was to that of the latter as
7 to 4. The peasants say that the change commences in the terminal
grain of the ear. The most remarkable point, as Dr. Asher positively
asserts, is that there are no intermediate varieties; but that a grain
produces a plant yielding either true Kubanka or true Saxonica. He
thinks that it would be interesting to sow here both kinds in good and
bad wheat soil and observe the result. Should you think it worth while
to make any such trial, and should you require further information, Dr.
Asher, whose address I enclose, will be happy to give any in his power.

LETTER 751. TO A. STEPHEN WILSON.
Basset, Southampton, April 29th [1878].

Your kind note and specimens have been forwarded to me here, where I am
staying at my son's house for a fortnight's complete rest, which I
required from rather too hard work. For this reason I will not now
examine the seeds, but will wait till returning home, when, with my son
Francis' aid, I will look to them.

I always felt, though without any good reason, rather sceptical about
Prof. Buckman's experiment, and I afterwards heard that a most wicked
and cruel trick had been played on him by some of the agricultural
students at Cirencester, who had sown seeds unknown to him in his
experimental beds. Whether he ever knew this I did not hear.

I am exceedingly glad that you are willing to look into the Russian
wheat case. It may turn out a mare's nest, but I have often
incidentally observed curious facts when making what I call "a fool's
experiment."

LETTER 752. TO A. STEPHEN WILSON.
Down, March 5th, 1879.

I have just returned home after an absence of a week, and your letter
was not forwarded to me; I mention this to account for my apparent
discourtesy in not having sooner thanked you. You have worked out the
subject with admirable care and clearness, and your drawings are
beautiful. I suspected that there was some error in the Russian belief,
but I did not think of the explanation which you have almost proved to
be the true one. It is an extremely interesting instance of a more
fertile variety beating out a less fertile one, and, in this case, one
much more valuable to man. With respect to publication, I am at a loss
to advise you, for I live a secluded life and do not see many
periodicals, or hear what is done at the various societies. It seems to
me that your paper should be published in some agricultural journal; for
it is not simply scientific, and would therefore not be published by the
Linnean or Royal Societies.

Would the Royal Agricultural Society be a fitting place? Unfortunately
I am not a member, and could not myself present it. Unless you think of
some better journal, there is the "Agricultural Gazette": I have
occasionally suggested articles for publication to the editor (though
personally unknown to me) which he has always accepted.

Permit me again to thank you for the thorough manner in which you have
worked out this case; to kill an error is as good a service as, and
sometimes even better than, the establishing a new truth or fact.

LETTER 753. TO A. STEPHEN WILSON.
Down, February 13th, 1880.

It was very kind of you to send me two numbers of the "Gardeners'
Chronicle" with your two articles, which I have read with much
interest. (753/1. "Gardeners' Chronicle," 1879, page 652; 1880, pages
108, 173.) You have quite convinced me, whatever Mr. Asher may say to
the contrary. I want to ask you a question, on the bare chance of your
being able to answer it, but if you cannot, please do not take the
trouble to write. The lateral branches of the silver fir often grow out
into knobs through the action of a fungus, Aecidium; and from these
knobs shoots grow vertically (753/2. The well-known "Witches-Brooms,"
or "Hexen-Besen," produced by the fungus Aecidium elatinum.) instead of
horizontally, like all the other twigs on the same branch. Now the
roots of Cruciferae and probably other plants are said to become knobbed
through the action of a fungus: now, do these knobs give rise to
rootlets? and, if so, do they grow in a new or abnormal direction?
(753/3. The parasite is probably Plasmodiophora: in this case no
abnormal rootlets have been observed, as far as we know.)

LETTER 754. TO W. THISELTON-DYER.
Down, June 18th, 1879.

The plants arrived last night in first-rate order, and it was very very
good of you to take so much trouble as to hunt them up yourself. They
seem exactly what I wanted, and if I fail it will not be for want of
perfect materials. But a confounded painter (I beg his pardon) comes
here to-night, and for the next two days I shall be half dead with
sitting to him; but after then I will begin to work at the plants and
see what I can do, and very curious I am about the results.

I have to thank you for two very interesting letters. I am delighted to
hear, and with surprise, that you care about old Erasmus D. God only
knows what I shall make of his life--it is such new kind of work to me.
(754/1. "Erasmus Darwin." By Ernst Krause. Translated from the German
by W.S. Dallas: with a preliminary notice by Charles Darwin. London,
1879. See "Life and Letters," III., pages 218-20.)

Thanks for case of sleeping Crotalaria--new to me. I quite agree to
every word you say about Ball's lecture (754/2. "On the Origin of the
Flora of the European Alps," "Geogr. Soc. Proc." Volume I., 1879, page
564. See Letter 395, Volume II.)--it is, as you say, like Sir W.
Thomson's meteorite. (754/3. In 1871 Lord Kelvin (Presidential Address
Brit. Assoc.) suggested that meteorites, "the moss-grown fragments from
the ruins of another world," might have introduced life to our planet.)
It is really a pity; it is enough to make Geographical Distribution
ridiculous in the eyes of the world. Frank will be interested about the
Auriculas; I never attended to this plant, for the powder did [not] seem
to me like true "bloom." (754/4. See Francis Darwin, on the relation
between "bloom" on leaves and the distribution of the stomata. "Linn.
Soc. Journ." Volume XXII., page 114.) This subject, however, for the
present only, has gone to the dogs with me.

I am sorry to hear of such a struggle for existence at Kew; but I have
often wondered how it is that you are all not killed outright.

I can most fully sympathise with you in your admiration of your little
girl. There is nothing so charming in this world, and we all in this
house humbly adore our grandchild, and think his little pimple of a nose
quite beautiful.

LETTER 755. TO G. BENTHAM.
Down, February 16th, 1880.

I have had real pleasure in signing Dyer's certificate. (755/1. As a
candidate for the Royal Society.) It was very kind in you to write to
me about the Orchideae, for it has pleased me to an extreme degree that
I could have been of the least use to you about the nature of the parts.
They are wonderful creatures, these orchids, and I sometimes think with
a glow of pleasure, when I remember making out some little point in
their method of fertilisation. (755/2. Published in "Life and
Letters," III., page 288.) With respect to terms, no doubt you will be
able to improve them greatly, for I knew nothing about the terms as used
in other groups of plants. Could you not invent some quite new term for
gland, implying viscidity? or append some word to gland. I used for
cirripedes "cement gland."

Your present work must be frightfully difficult. I looked at a few
dried flowers, and could make neither heads nor tails of them; and I
well remember wondering what you would do with them when you came to the
group in the "Genera Plantarum." I heartily wish you safe through your
work,...

LETTER 756. TO F.M. BALFOUR.
Down, September 4th, 1880.

I hope that you will not think me a great bore, but I have this minute
finished reading your address at the British Association; and it has
interested me so much that I cannot resist thanking you heartily for the
pleasure derived from it, not to mention the honour which you have done
me. (756/1. Presidential address delivered by Prof. F.M. Balfour
before the Biological Section at the British Association meeting at
Swansea (1880).) The recent progress of embryology is indeed splendid.
I have been very stupid not to have hitherto read your book, but I have
had of late no spare time; I have now ordered it, and your address will
make it the more interesting to read, though I fear that my want of
knowledge will make parts unintelligible to me. (756/2. "A Treatise on
Comparative Embryology," 2 volumes. London, 1880.) In my recent work
on plants I have been astonished to find to how many very different
stimuli the same small part--viz., the tip of the radicle--is sensitive,
and has the power of transmitting some influence to the adjoining part
of the radicle, exciting it to bend to or from the source of irritation
according to the needs of the plant (756/3. See Letter 757.); and all
this takes place without any nervous system! I think that such facts
should be kept in mind when speculating on the genesis of the nervous
system. I always feel a malicious pleasure when a priori conclusions
are knocked on the head: and therefore I felt somewhat like a devil
when I read your remarks on Herbert Spencer (756/4. Prof. Balfour
discussed Mr. Herbert Spencer's views on the genesis of the nervous
system, and expressed the opinion that his hypothesis was not borne out
by recent discoveries. "The discovery that nerves have been developed
from processes of epithelial cells gives a very different conception of
their genesis to that of Herbert Spencer, which makes them originate
from the passage of nervous impulses through a track of mingled
colloids..." (loc. cit., page 644.))...Our recent visit to Cambridge was
a brilliant success to us all, and will ever be remembered by me with
much pleasure.

LETTER 757. TO JAMES PAGET.

(757/1. During the closing years of his life, Darwin began to
experimentise on the possibility of producing galls artificially. A
letter to Sir J.D. Hooker (November 3rd, 1880) shows the interest which
he felt in the question:--

"I was delighted with Paget's essay (757/2. An address on "Elemental
Pathology," delivered before the British Medical Association, August
1880, and published in the Journal of the Association.); I hear that he
has occasionally attended to this subject from his youth...I am very
glad he has called attention to galls: this has always seemed to me a
profoundly interesting subject; and if I had been younger would take it
up."

His interest in this subject was connected with his ever-present wish to
learn something of the causes of variation. He imagined to himself
wonderful galls caused to appear on the ovaries of plants, and by these
means he thought it possible that the seed might be influenced, and thus
new varieties arise. (757/3. There would have been great difficulties
about this line of research, for when the sexual organs of plants are
deformed by parasites (in the way he hoped to effect by poisons)
sterility almost always results. See Molliard's "Les Cecidies
Florales," "Ann. Sci. Nat." 1895, Volume I., page 228.) He made a
considerable number of experiments by injecting various reagents into
the tissues of leaves, and with some slight indications of success.
(757/4. The above passage is reprinted, with alterations, from "Life
and Letters," III., page 346.)

The following letter to the late Sir James Paget refers to the same
subject.)

Down, November 14th, 1880.

I am very much obliged for your essay, which has interested me greatly.
What indomitable activity you have! It is a surprising thought that the
diseases of plants should illustrate human pathology. I have the German
"Encyclopaedia," and a few weeks ago told my son Francis that the
article on the diseases of plants would be well worth his study; but I
did not know it was written by Dr. Frank, for whom I entertain a high
respect as a first-rate observer and experimentiser, though for some
unknown reason he has been a good deal snubbed in Germany. I can give
you one good case of regrowth in plants, recently often observed by me,
though only externally, as I do not know enough of histology to follow
out details. It is the tip of the radicle of a germinating common bean.
The case is remarkable in some respects, for the tip is sensitive to
various stimuli, and transmits an order, causing the upper part of the
radicle to bend. When the tip (for a length of about 1 mm.) is cut
transversely off, the radicle is not acted on by gravitation or other
irritants, such as contact, etc., etc., but a new tip is regenerated in
from two to four days, and then the radicle is again acted on by
gravitation, and will bend to the centre of the earth. The tip of the
radicle is a kind of brain to the whole growing part of the radicle!
(757/5. We are indebted to Mr. Archer-Hind for the translation of the
following passage from Plato ("Timaeus," 90A): "The reason is every
man's guardian genius (daimon), and has its habitation in our brain; it
is this that raises man (who is a plant, not of earth but of heaven) to
an erect posture, suspending the head and root of us from the heavens,
which are the birthplace of our soul, and keeping all the body upright."
On the perceptions of plants, see "Nature," November 14th, 1901--a
lecture delivered at the Glasgow meeting of the British Association by
Francis Darwin. See also Bonitz, "Index Aristotelicus," S.V. phuton.)

My observation will be published in about a week's time, and I would
have sent you the book, but I do not suppose that there is anything else
in the book which would interest you. I am delighted that you have
drawn attention to galls. They have always seemed to me profoundly
interesting. Many years ago I began (but failed for want of time,
strength, and health, as on infinitely many other occasions) to
experimentise on plants, by injecting into their tissues some alkaloids
and the poison of wasps, to see if I could make anything like galls. If
I remember rightly, in a few cases the tissues were thickened and
hardened. I began these experiments because if by different poisons I
could have affected slightly and differently the tissues of the same
plant, I thought there would be no insuperable difficulty in the fittest
poisons being developed by insects so as to produce galls adapted for
them. Every character, as far as I can see, is apt to vary. Judging
from one of your sentences you will smile at this.

To any one believing in my pangenesis (if such a man exists) there does
not seem to me any extreme difficulty in understanding why plants have
such little power of regeneration; for there is reason to think that my
imaginary gemmules have small power of passing from cell to cell.
(757/6. On regeneration after injury, see Massart, "La Cicatrisation
chez les Vegetaux," in Volume 57 (1898) of the "Memoires Couronnes,"
published by the Royal Academy of Belgium. An account of the literature
is given by the author.)

Forgive me for scribbling at such unreasonable length; but you are to
blame for having interested me so much.

P.S.--Perhaps you may remember that some two years ago you asked me to
lunch with you, and proposed that I should offer myself again. Whenever
I next come to London, I will do so, and thus have the pleasure of
seeing you.

LETTER 758. TO W. THISELTON-DYER.

(758/1. "The Power of Movement in Plants" was published early in
November, 1880. Sir W. Thiselton-Dyer, in writing to thank Darwin for a
copy of the book, had (November 20th) compared a structure in the
seedling Welwitschia with the "peg" of Cucurbita (see "Power of
Movement," page 102). Dyer wrote: "One peculiar feature in the
germinating embryo is a lateral hypocotyledonary process, which
eventually serves as an absorbent organ, by which the nutriment of the
endosperm is conveyed to the seedling. Such a structure was quite new
to me, and Bower and I were disposed to see in it a representative of
the foot in Selaginella, when I saw the account of Flahault's 'peg.'"
Flahault, it should be explained, was the discoverer of the curious peg
in Cucurbita. Prof. Bower wrote a paper ("On the Germination and
Histology of the seedling of Welwitschia mirabilis" in the "Quart.
Journ. Microscop. Sci." XXI., 1881, page 15.)

Down, November 28th [1880].

Very many thanks for your most kind note, but you think too highly of
our work--not but what this is very pleasant.

I am deeply interested about Welwitschia. When at work on the pegs or
projections I could not imagine how they were first developed, before
they could have been of mere mechanical use. Now it seems possible that
a circle between radicle and hypocotyl may be permeable to fluids, and
thus have given rise to projections so as to expose larger surface.
Could you test Welwitschia with permanganate of potassium: if, like my
pegs, the lower surface would be coloured brown like radicle, and upper
surface left white like hypocotyl. If such an idea as yours, of an
absorbing organ, had ever crossed my mind, I would have tried many
hypocotyls in weak citrate of ammonia, to see if it penetrated on line
of junction more easily than elsewhere. I daresay the projection in
Abronia and Mirabilis may be an absorbent organ. It was very good fun
bothering the seeds of Cucurbita by planting them edgeways, as would
never naturally occur, and then the peg could not act properly. 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. Indeed, you are
greatly mistaken if you doubt for one moment on the very great value of
your constant and most kind assistance to us. I have not seen the
pamphlet, and shall be very glad to keep it. Frank, when he comes home,
will be much interested and pleased with your letter. Pray give my
kindest remembrance to Mrs. Dyer.

This is a very untidy note, but I am very tired with dissecting worms
all day. Read the last chapter of our book, and then you will know the
whole contents.

LETTER 759. TO H. VOCHTING.
Down, December 16th, 1880.

Absence from home has prevented me from sooner thanking you for your
kind present of your several publications. I procured some time ago
your "Organbilding" (759/1. "Organbildung im Pflanzenreich," 1878.)
etc., but it was too late for me to profit by it for my book, as I was
correcting the press. I read only parts, but my son Francis read the
whole with care and told me much about it, which greatly interested me.
I also read your article in the "Bot. Zeitung." My son began at once
experimenting, to test your views, and this very night will read a paper
before the Linnean Society on the roots of Rubus (759/2. Francis
Darwin, "The Theory of the Growth of Cuttings" ("Linn. Soc. Journ."
XVIII.). [I take this opportunity of expressing my regret that at page
417, owing to neglect of part of Vochting's facts, I made a criticism of
his argument which cannot be upheld.--F.D.].), and I think that you will
be pleased to find how well his conclusions agree with yours. He will
of course send you a copy of his paper when it is printed. I have sent
him your letter, which will please him if he agrees with me; for your
letter has given me real pleasure, and I did not at all know what the
many great physiologists of Germany, Switzerland, and Holland would
think of it ["The Power of Movement," etc.]. I was quite sorry to read
Sachs' views about root-forming matter, etc., for I have an unbounded
admiration for Sachs. In this country we are dreadfully behind in
Physiological Botany.

LETTER 760. TO A. DE CANDOLLE.
Down, January 24th, 1881.

It was extremely kind of you to write me so long and valuable a letter,
the whole of which deserves careful consideration. I have been
particularly pleased at what you say about the new terms used, because I
have often been annoyed at the multitude of new terms lately invented in
all branches of Biology in Germany; and I doubted much whether I was not
quite as great a sinner as those whom I have blamed. When I read your
remarks on the word "purpose" in your "Phytographie," I vowed that I
would not use it again; but it is not easy to cure oneself of a vicious
habit. It is also difficult for any one who tries to make out the use
of a structure to avoid the word purpose. I see that I have probably
gone beyond my depth in discussing plurifoliate and unifoliate leaves;
but in such a case as that of Mimosa albida, where rudiments of
additional leaflets are present, we must believe that they were well
developed in the progenitor of the plant. So again, when the first true
leaf differs widely in shape from the older leaves, and resembles the
older leaves in allied species, is it not the most simple explanation
that such leaves have retained their ancient character, as in the case
of the embryos of so many animals?

Your suggestion of examining the movements of vertical leaves with an
equal number of stomata on both sides, with reference to the light,
seems to me an excellent one, and I hope that my son Francis may follow
it up. But I will not trouble you with any more remarks about our book.
My son will write to you about the diagram.

Let me add that I shall ever remember with pleasure your visit here last
autumn.

LETTER 761. TO J. LUBBOCK (Lord Avebury).
Down, April 16th [1881].

Will you be so kind as to send and lend me the Desmodium gyrans by the
bearer who brings this note.

Shortly after you left I found my notice of the seeds in the "Gardeners'
Chronicle," which please return hereafter, as I have no other copy.
(761/1. "Note on the Achenia of Pumilio argyrolepis." "Gardeners'
Chronicle," 1861, page 4.) I do not think that I made enough about the
great power of absorption of water by the corolla-like calyx or pappus.
It seems to me not unlikely that the pappus of other Compositae may be
serviceable to the seeds, whilst lying on the ground, by absorbing the
dew which would be especially apt to condense on the fine points and
filaments of the pappus. Anyhow, this is a point which might be easily
investigated. Seeds of Tussilago, or groundsel (761/2. It is not clear
whether Tussilago or groundsel (Senecio vulgaris) is meant; or whether
he was not sure which of the two plants becomes slimy when wetted.),
emit worm-like masses of mucus, and it would be curious to ascertain
whether wetting the pappus alone would suffice to cause such secretion.
(761/3. See Letter 707.)

LETTER 762. TO G.J. ROMANES.
Down, April 18th, 1881.

I am extremely glad of your success with the flashing light. (762/1.
Romanes' paper on the effect of intermittent light on heliotropism was
the "Proc. Royal Soc." Volume LIV., page 333.) If plants are acted on
by light, like some of the lower animals, there is an additional point
of interest, as it seems to me, in your results. Most botanists believe
that light causes a plant to bend to it in as direct a manner as light
affects nitrate of silver. I believe that it merely tells the plant to
which side to bend, and I see indications of this belief prevailing even
with Sachs. Now it might be expected that light would act on a plant in
something the same manner as on the lower animals. As you are at work
on this subject, I will call your attention to another point. Wiesner,
of Vienna (who has lately published a great book on heliotropism) finds
that an intermittent light, say of 20 minutes, produces the same effect
as a continuous light of, say 60 m. (762/2. Wiesner's papers on
heliotropism are in the "Denkschriften" of the Vienna Academy, Volumes
39 and 43.) So that Van Tieghem, in the first part of his book which
has just appeared, remarks, the light during 40 m. out of the 60 m.
produced no effect. I observed an analogous case described in my book.
(762/3. "Power of Movement," page 459.)