[My father mentions in his 'Autobiography' (volume i.) that he was led
to take up the subject of climbing plants by reading Dr. Gray's paper,
"Note on the Coiling of the Tendrils of Plants." ('Proc. Amer. Acad. of
Arts and Sciences,' 1858.) This essay seems to have been read in 1862,
but I am only able to guess at the date of the letter in which he asks
for a reference to it, so that the precise date of his beginning this
work cannot be determined.
In June 1863 he was certainly at work, and wrote to Sir J.D. Hooker for
information as to previous publications on the subject, being then in
ignorance of Palm's and H. v. Mohl's works on climbing plants, both of
which were published in 1827.]
CHARLES DARWIN TO J.D. HOOKER. Down [June] 25 [1863].
My dear Hooker,
I have been observing pretty carefully a little fact which has surprised
me; and I want to know from you and Oliver whether it seems new or odd
to you, so just tell me whenever you write; it is a very trifling fact,
so do not answer on purpose.
I have got a plant of Echinocystis lobata to observe the irritability
of the tendrils described by Asa Gray, and which of course, is plain
enough. Having the plant in my study, I have been surprised to find
that the uppermost part of each branch (i.e. the stem between the two
uppermost leaves excluding the growing tip) is CONSTANTLY and slowly
twisting round making a circle in from one-half to two hours; it
will sometimes go round two or three times, and then at the same rate
untwists and twists in opposite directions. It generally rests half
an hour before it retrogrades. The stem does not become permanently
twisted. The stem beneath the twisting portion does not move in the
least, though not tied. The movement goes on all day and all early
night. It has no relation to light for the plant stands in my window
and twists from the light just as quickly as towards it. This may be a
common phenomenon for what I know, but it confounded me quite, when I
began to observe the irritability of the tendrils. I do not say it is
the final cause, but the result is pretty, for the plant every one and
a half or two hours sweeps a circle (according to the length of the
bending shoot and the length of the tendril) of from one foot to twenty
inches in diameter, and immediately that the tendril touches any object
its sensitiveness causes it immediately to seize it; a clever gardener,
my neighbour, who saw the plant on my table last night, said: "I
believe, Sir, the tendrils can see, for wherever I put a plant it finds
out any stick near enough." I believe the above is the explanation, viz.
that it sweeps slowly round and round. The tendrils have some sense, for
they do not grasp each other when young.
Yours affectionately, C. DARWIN.
CHARLES DARWIN TO J.D. HOOKER. Down, July 14 [1863].
My dear Hooker,
I am getting very much amused by my tendrils, it is just the sort of
niggling work which suits me, and takes up no time and rather rests me
whilst writing. So will you just think whether you know any plant, which
you could give or lend me, or I could buy, with tendrils, remarkable in
any way for development, for odd or peculiar structure, or even for an
odd place in natural arrangement. I have seen or can see Cucurbitaceae,
Passion-flower, Virginian-creeper, Cissus discolor, Common-pea
and Everlasting-pea. It is really curious the diversification of
irritability (I do not mean the spontaneous movement, about which I
wrote before and correctly, as further observation shows): for instance,
I find a slight pinch between the thumb and finger at the end of the
tendril of the Cucurbitaceae causes prompt movement, but a pinch excites
no movement in Cissus. The cause is that one side alone (the concave) is
irritable in the former; whereas both sides are irritable in Cissus, so
if you excite at the same time both OPPOSITE sides there is no movement,
but by touching with a pencil the two branches of the tendril, in any
part whatever, you cause movement towards that point; so that I can
mould, by a mere touch, the two branches into any shape I like...
CHARLES DARWIN TO ASA GRAY. Down, August 4 [1863].
My present hobby-horse I owe to you, viz. the tendrils: their
irritability is beautiful, as beautiful in all its modifications as
anything in Orchids. About the SPONTANEOUS movement (independent of
touch) of the tendrils and upper internodes, I am rather taken aback by
your saying, "is it not wel-known?" I can find nothing in any book which
I have... The spontaneous movement of the tendrils is independent of the
movement of the upper internodes, but both work harmoniously together
in sweeping a circle for the tendrils to grasp a stick. So with all
climbing plants (without tendrils) as yet examined, the upper internodes
go on night and day sweeping a circle in one fixed direction. It is
surprising to watch the Apocyneae with shoots 18 inches long (beyond the
supporting stick), steadily searching for something to climb up. When
the shoot meets a stick, the motion at that point is arrested, but in
the upper part is continued; so that the climbing of all plants yet
examined is the simple result of the spontaneous circulatory movement of
the upper internodes. Pray tell me whether anything has been published
on this subject? I hate publishing what is old; but I shall hardly
regret my work if it is old, as it has much amused me...
CHARLES DARWIN TO ASA GRAY. May 28, 1864.
... An Irish nobleman on his death-bed declared that he could
conscientiously say that he had never throughout life denied himself any
pleasure; and I can conscientiously say that I have never scrupled to
trouble you; so here goes.--Have you travelled South, and can you tell
me whether the trees, which Bignonia capreolata climbs, are covered with
moss or filamentous lichen or Tillandsia? (He subsequently learned from
Dr. Gray that Polypodium incanum abounds on the trees in the districts
where this species of Bignonia grows. See 'Climbing Plants,' page 103.)
I ask because its tendrils abhor a simple stick, do not much relish
rough bark, but delight in wool or moss. They adhere in a curious manner
by making little disks, like the Ampelopsis... By the way, I will enclose
some specimens, and if you think it worth while, you can put them under
the simple microscope. It is remarkable how specially adapted some
tendrils are; those of Eccremocarpus scaber do not like a stick, will
have nothing to say to wool; but give them a bundle of culms of grass,
or a bundle of bristles and they seize them well.
CHARLES DARWIN TO J.D. HOOKER. Down, June 10 [1864].
... I have now read two German books, and all I believe that has been
written on climbers, and it has stirred me up to find that I have a
good deal of new matter. It is strange, but I really think no one has
explained simple twining plants. These books have stirred me up, and
made me wish for plants specified in them. I shall be very glad of those
you mention. I have written to Veitch for young Nepenthes and Vanilla
(which I believe will turn out a grand case, though a root creeper),
if I cannot buy young Vanilla I will ask you. I have ordered a
leaf-climbing fern, Lygodium. All this work about climbers would hurt
my conscience, did I think I could do harder work. (He was much out of
health at this time.)
[He continued his observations on climbing plants during the prolonged
illness from which he suffered in the autumn of 1863, and in the
following spring. He wrote to Sir J.D. Hooker, apparently in March
1864:--
"For several days I have been decidedly better, and what I lay much
stress on (whatever doctors say), my brain feels far stronger, and I
have lost many dreadful sensations. The hot-house is such an amusement
to me, and my amusement I owe to you, as my delight is to look at the
many odd leaves and plants from Kew... The only approach to work which
I can do is to look at tendrils and climbers, this does not distress my
weakened brain. Ask Oliver to look over the enclosed queries (and do you
look) and amuse a broken-down brother naturalist by answering any which
he can. If you ever lounge through your houses, remember me and climbing
plants."
On October 29, 1864, he wrote to Dr. Gray:--
"I have not been able to resist doing a little more at your godchild, my
climbing paper, or rather in size little book, which by Jove I will have
copied out, else I shall never stop. This has been new sort of work
for me, and I have been pleased to find what a capital guide for
observations a full conviction of the change of species is."
On January 19, 1865, he wrote to Sir J.D. Hooker:--
"It is working hours, but I am trying to take a day's holiday, for I
finished and despatched yesterday my climbing paper. For the last ten
days I have done nothing but correct refractory sentences, and I loathe
the whole subject."
A letter to Dr. Gray, April 9, 1865, has a word or two on the subject:--
"I have begun correcting proofs of my paper on 'Climbing Plants.' I
suppose I shall be able to send you a copy in four or five weeks. I
think it contains a good deal new and some curious points, but it is so
fearfully long, that no one will ever read it. If, however, you do not
SKIM through it, you will be an unnatural parent, for it is your child."
Dr. Gray not only read it but approved of it, to my father's great
satisfaction, as the following extracts show:--
"I was much pleased to get your letter of July 24th. Now that I can
do nothing, I maunder over old subjects, and your approbation of my
climbing paper gives me VERY great satisfaction. I made my observations
when I could do nothing else and much enjoyed it, but always doubted
whether they were worth publishing. I demur to its not being necessary
to explain in detail about the spires in CAUGHT tendrils running in
opposite directions; for the fact for a long time confounded me, and
I have found it difficult enough to explain the cause to two or three
persons." (August 15, 1865.)
"I received yesterday your article (In the September number of
'Silliman's Journal,' concluded in the January number, 1866.) on
climbers, and it has pleased me in an extraordinary and even silly
manner. You pay me a superb compliment, and as I have just said to my
wife, I think my friends must perceive that I like praise, they give me
such hearty doses. I always admire your skill in reviews or abstracts,
and you have done this article excellently and given the whole essence
of my paper... I have had a letter from a good Zoologist in S. Brazil,
F. Muller, who has been stirred up to observe climbers and gives me some
curious cases of BRANCH-climbers, in which branches are converted
into tendrils, and then continue to grow and throw out leaves and new
branches, and then lose their tendril character." (October 1865.)
The paper on Climbing Plants was republished in 1875, as a separate
book. The author had been unable to give his customary amount of care to
the style of the original essay, owing to the fact that it was written
during a period of continued ill-health, and it was now found to require
a great deal of alteration. He wrote to Sir J.D. Hooker (March 3,
1875): "It is lucky for authors in general that they do not require such
dreadful work in merely licking what they write into shape." And to Mr.
Murray in September he wrote: "The corrections are heavy in 'Climbing
Plants,' and yet I deliberately went over the MS. and old sheets three
times." The book was published in September 1875, an edition of 1500
copies was struck off; the edition sold fairly well, and 500 additional
copies were printed in June of the following year.]
INSECTIVOROUS PLANTS.
[In the summer of 1860 he was staying at the house of his sister-in-law,
Miss Wedgwood, in Ashdown Forest, whence he wrote (July 29, 1860), to
Sir Joseph Hooker;--
"Latterly I have done nothing here; but at first I amused myself with
a few observations on the insect-catching power of Drosera; and I must
consult you some time whether my 'twaddle' is worth communicating to the
Linnean Society."
In August he wrote to the same friend:--
"I will gratefully send my notes on Drosera when copied by my copier:
the subject amused me when I had nothing to do."
He has described in the 'Autobiography' (volume i.), the general nature
of these early experiments. He noticed insects sticking to the leaves,
and finding that flies, etc., placed on the adhesive glands were held
fast and embraced, he suspected that the leaves were adapted to supply
nitrogenous food to the plant. He therefore tried the effect on the
leaves of various nitrogenous fluids--with results which, as far as they
went, verified his surmise. In September, 1860, he wrote to Dr. Gray:--
"I have been infinitely amused by working at Drosera: the movements
are really curious; and the manner in which the leaves detect certain
nitrogenous compounds is marvellous. You will laugh; but it is, at
present, my full belief (after endless experiments) that they detect
(and move in consequence of) the 1/2880 part of a single grain of
nitrate of ammonia; but the muriate and sulphate of ammonia bother their
chemical skill, and they cannot make anything of the nitrogen in these
salts! I began this work on Drosera in relation to GRADATION as throwing
light on Dionaea."
Later in the autumn he was again obliged to leave home for Eastbourne,
where he continued his work on Drosera. The work was so new to him that
he found himself in difficulties in the preparation of solutions, and
became puzzled over fluid and solid ounces, etc. etc. To a friend, the
late Mr. E. Cresy, who came to his help in the matter of weights and
measures, he wrote giving an account of the experiments. The extract
(November 2, 1860) which follows illustrates the almost superstitious
precautions he often applied to his researches:--
"Generally I have scrutinised every gland and hair on the leaf before
experimenting; but it occurred to me that I might in some way affect the
leaf; though this is almost impossible, as I scrutinised with equal care
those that I put into distilled water (the same water being used for
dissolving the carbonate of ammonia). I then cut off four leaves (not
touching them with my fingers), and put them in plain water, and four
other leaves into the weak solution, and after leaving them for an hour
and a half, I examined every hair on all eight leaves; no change on the
four in water; every gland and hair affected in those in ammonia.
"I had measured the quantity of weak solution, and I counted the glands
which had absorbed the ammonia, and were plainly affected; the result
convinced me that each gland could not have absorbed more than 1/64000
or 1/65000 of a grain. I have tried numbers of other experiments all
pointing to the same result. Some experiments lead me to believe that
very sensitive leaves are acted on by much smaller doses. Reflect
how little ammonia a plant can get growing on poor soil--yet it is
nourished. The really surprising part seems to me that the effect should
be visible, and not under very high power; for after trying a high
power, I thought it would be safer not to consider any effect which
was not plainly visible under a two-thirds object glass and middle
eye-piece. The effect which the carbonate of ammonia produces is the
segregation of the homogeneous fluid in the cells into a cloud of
granules and colourless fluid; and subsequently the granules coalesce
into larger masses, and for hours have the oddest movements--coalescing,
dividing, coalescing ad infinitum. I do not know whether you will care
for these ill-written details; but, as you asked, I am sure I am bound
to comply, after all the very kind and great trouble which you have
taken."
On his return home he wrote to Sir J.D. Hooker (November 21, 1860):--
"I have been working like a madman at Drosera. Here is a fact for you
which is certain as you stand where you are, though you won't believe
it, that a bit of hair 1/78000 of one grain in weight placed on gland,
will cause ONE of the gland-bearing hairs of Drosera to curve inwards,
and will alter the condition of the contents of every cell in the
foot-stalk of the gland."
And a few days later to Lyell:--
"I will and must finish my Drosera MS., which will take me a week, for,
at the present moment, I care more about Drosera than the origin of all
the species in the world. But I will not publish on Drosera till next
year, for I am frightened and astounded at my results. I declare it is
a certain fact, that one organ is so sensitive to touch, that a weight
seventy-eight times less than that, viz., 1/1000 of a grain, which
will move the best chemical balance, suffices to cause a conspicuous
movement. Is it not curious that a plant should be far more sensitive to
the touch than any nerve in the human body? Yet I am perfectly sure that
this is true. When I am on my hobby-horse, I never can resist telling my
friends how well my hobby goes, so you must forgive the rider."
The work was continued, as a holiday task, at Bournemouth, where he
stayed during the autumn of 1862. The discussion in the following letter
on "nervous matter" in Drosera is of interest in relation to recent
researches on the continuity of protoplasm from cell to cell:]
CHARLES DARWIN TO J.D. HOOKER. Cliff Cottage, Bournemouth. September 26
[1862].
My dear Hooker,
Do not read this till you have leisure. If that blessed moment ever
comes, I should be very glad to have your opinion on the subject of this
letter. I am led to the opinion that Drosera must have diffused matter
in organic connection, closely analogous to the nervous matter of
animals. When the glands of one of the papillae or tentacles, in its
natural position is supplied with nitrogenised fluid and certain other
stimulants, or when loaded with an extremely slight weight, or when
struck several times with a needle, the pedicel bends near its base in
under one minute. These varied stimulants are conveyed down the pedicel
by some means; it cannot be vibration, for drops of fluid put on quite
quietly cause the movement; it cannot be absorption of the fluid from
cell to cell, for I can see the rate of absorption, which though quick,
is far slower, and in Dionaea the transmission is instantaneous;
analogy from animals would point to transmission through nervous matter.
Reflecting on the rapid power of absorption in the glands, the extreme
sensibility of the whole organ, and the conspicuous movement caused by
varied stimulants, I have tried a number of substances which are not
caustic or corrosive,... but most of which are known to have a remarkable
action on the nervous matter of animals. You will see the results in
the enclosed paper. As the nervous matter of different animals are
differently acted on by the same poisons, one would not expect the
same action on plants and animals; only if plants have diffused nervous
matter, some degree of analogous action. And this is partially the case.
Considering these experiments, together with the previously made remarks
on the functions of the parts, I cannot avoid the conclusion,
that Drosera possesses matter at least in some degree analogous in
constitution and function to nervous matter. Now do tell me what you
think, as far as you can judge from my abstract; of course many more
experiments would have to be tried; but in former years I tried on the
whole leaf, instead of on separate glands, a number of innocuous (This
line of investigation made him wish for information on the action
of poisons on plants; as in many other cases he applied to Professor
Oliver, and in reference to the result wrote to Hooker: "Pray thank
Oliver heartily for his heap of references on poisons.") substances,
such as sugar, gum, starch, etc., and they produced no effect. Your
opinion will aid me in deciding some future year in going on with
this subject. I should not have thought it worth attempting, but I had
nothing on earth to do.
My dear Hooker, Yours very sincerely, CH. DARWIN.
P.S.--We return home on Monday 28th. Thank Heaven!
[A long break now ensued in his work on insectivorous plants, and it was
not till 1872 that the subject seriously occupied him again. A passage
in a letter to Dr. Asa Gray, written in 1863 or 1864, shows, however,
that the question was not altogether absent from his mind in the
interim:--
"Depend on it you are unjust on the merits of my beloved Drosera; it is
a wonderful plant, or rather a most sagacious animal. I will stick up
for Drosera to the day of my death. Heaven knows whether I shall ever
publish my pile of experiments on it."
He notes in his diary that the last proof of the 'Expression of the
Emotions' was finished on August 22, 1872, and that he began to work on
Drosera on the following day.]
CHARLES DARWIN TO ASA GRAY. [Sevenoaks], October 22 [1872].
... I have worked pretty hard for four or five weeks on Drosera, and
then broke down; so that we took a house near Sevenoaks for three weeks
(where I now am) to get complete rest. I have very little power of
working now, and must put off the rest of the work on Drosera till next
spring, as my plants are dying. It is an endless subject, and I must cut
it short, and for this reason shall not do much on Dionaea. The point
which has interested me most is tracing the NERVES! which follow the
vascular bundles. By a prick with a sharp lancet at a certain point,
I can paralyse one-half the leaf, so that a stimulus to the other half
causes no movement. It is just like dividing the spinal marrow of a
frog:--no stimulus can be sent from the brain or anterior part of the
spine to the hind legs; but if these latter are stimulated, they move by
reflex action. I find my old results about the astonishing sensitiveness
of the nervous system (!?)of Drosera to various stimulants fully
confirmed and extended...
[His work on digestion in Drosera and other points in the physiology of
the plant soon led him into regions where his knowledge was defective,
and here the advice and assistance which he received from Dr. Burdon
Sanderson was of much value:]
CHARLES DARWIN TO J. BURDON SANDERSON. Down, July 25, 1873.
My dear Dr. Sanderson,
I should like to tell you a little about my recent work with Drosera, to
show that I have profited by your suggestions, and to ask a question or
two.
1. It is really beautiful how quickly and well Drosera and Dionaea
dissolve little cubes of albumen and gelatine. I kept the same sized
cubes on wet moss for comparison. When you were here I forgot that I had
tried gelatine, but albumen is far better for watching its dissolution
and absorption. Frankland has told me how to test in a rough way for
pepsin; and in the autumn he will discover what acid the digestive juice
contains.
2. A decoction of cabbage-leaves and green peas causes as much
inflection as an infusion of raw meat; a decoction of grass is less
powerful. Though I hear that the chemists try to precipitate all albumen
from the extract of belladonna, I think they must fail, as the extract
causes inflection, whereas a new lot of atropine, as well as the
valerianate [of atropine], produce no effect.
3. I have been trying a good many experiments with heated water... Should
you not call the following case one of heat rigor? Two leaves were
heated to 130 deg, and had every tentacle closely inflected; one was
taken out and placed in cold water, and it re-expanded; the other was
heated to 145 deg, and had not the least power of re-expansion. Is not
this latter case heat rigor? If you can inform me, I should very much
like to hear at what temperature cold-blooded and invertebrate animals
are killed.
4. I must tell you my final result, of which I am sure, [as to] the
sensitiveness of Drosera. I made a solution of one part of phosphate of
ammonia by weight to 218,750 of water; of this solution I gave so much
that a leaf got 1/8000 of a grain of the phosphate. I then counted the
glands, and each could have got only 1/1552000 of a grain; this being
absorbed by the glands, sufficed to cause the tentacles bearing these
glands to bend through an angle of 180 deg. Such sensitiveness requires
hot weather, and carefully selected young yet mature leaves. It strikes
me as a wonderful fact. I must add that I took every precaution, by
trying numerous leaves at the same time in the solution and in the same
water which was used for making the solution.
5. If you can persuade your friend to try the effects of carbonate of
ammonia on the aggregation of the white blood corpuscles, I should very
much like to hear the result.
I hope this letter will not have wearied you.
Believe me, yours very sincerely, CHARLES DARWIN.
CHARLES DARWIN TO W. THISELTON DYER. Down, 24 [December 1873?].
My dear Mr. Dyer,
I fear that you will think me a great bore, but I cannot resist telling
you that I have just found out that the leaves of Pinguicula possess
a beautifully adapted power of movement. Last night I put on a row of
little flies near one edge of two YOUNGISH leaves; and after 14 hours
these edges are beautifully folded over so as to clasp the flies, thus
bringing the glands into contact with the upper surfaces of the flies,
and they are now secreting copiously above and below the flies and no
doubt absorbing. The acid secretion has run down the channelled edge and
has collected in the spoon-shaped extremity, where no doubt the glands
are absorbing the delicious soup. The leaf on one side looks just like
the helix of a human ear, if you were to stuff flies within the fold.
Yours most sincerely,
CH. DARWIN.
CHARLES DARWIN TO ASA GRAY. Down, June 3 [1874].
... I am now hard at work getting my book on Drosera & Co. ready for the
printers, but it will take some time, for I am always finding out new
points to observe. I think you will be interested by my observations on
the digestive process in Drosera; the secretion contains an acid of the
acetic series, and some ferment closely analogous to, but not identical
with, pepsin; for I have been making a long series of comparative
trials. No human being will believe what I shall publish about the
smallness of the doses of phosphate of ammonia which act.
... I began reading the Madagascar squib (A description of a carnivorous
plant supposed to subsist on human beings.) quite gravely, and when I
found it stated that Felis and Bos inhabited Madagascar, I thought it
was a false story, and did not perceive it was a hoax till I came to the
woman...
CHARLES DARWIN TO F.C. DONDERS. (Professor Donders, the well-known
physiologist of Utrecht.) Down, July 7, 1874.
My dear Professor Donders,
My son George writes to me that he has seen you, and that you have been
very kind to him, for which I return to you my cordial thanks. He
tells me on your authority, of a fact which interests me in the highest
degree, and which I much wish to be allowed to quote. It relates to the
action of one millionth of a grain of atropine on the eye. Now will you
be so kind, whenever you can find a little leisure, to tell me whether
you yourself have observed this fact, or believe it on good authority.
I also wish to know what proportion by weight the atropine bore to the
water solution, and how much of the solution was applied to the eye. The
reason why I am so anxious on this head is that it gives some support
to certain facts repeatedly observed by me with respect to the action of
phosphate of ammonia on Drosera. The 1/4000000 of a grain absorbed by
a gland clearly makes the tentacle which bears this gland become
inflected; and I am fully convinced that 1/20000000 of a grain of the
crystallised salt (i.e. containing about one-third of its weight of
water of crystallisation) does the same. Now I am quite unhappy at the
thought of having to publish such a statement. It will be of great value
to me to be able to give any analogous facts in support. The case of
Drosera is all the more interesting as the absorption of the salt or
any other stimulant applied to the gland causes it to transmit a motor
influence to the base of the tentacle which bears the gland.
Pray forgive me for troubling you, and do not trouble yourself to answer
this until your health is fully re-established.
Pray believe me, Yours very sincerely, CHARLES DARWIN.
[During the summer of 1874 he was at work on the genus Utricularia,
and he wrote (July 16th) to Sir J.D. Hooker giving some account of the
progress of his work:--
"I am rather glad you have not been able to send Utricularia, for the
common species has driven F. and me almost mad. The structure is MOST
complex. The bladders catch a multitude of Entomostraca, and larvae of
insects. The mechanism for capture is excellent. But there is much that
we cannot understand. From what I have seen to-day, I strongly suspect
that it is necrophagous, i.e. that it cannot digest, but absorbs
decaying matter."
He was indebted to Lady Dorothy Nevill for specimens of the curious
Utricularia montana, which is not aquatic like the European species,
but grows among the moss and debris on the branches of trees. To this
species the following letter refers:]
CHARLES DARWIN TO LADY DOROTHY NEVILL. Down September 18 [1874].
Dear Lady Dorothy Nevill,
I am so much obliged to you. I was so convinced that the bladders were
with the leaves that I never thought of removing the moss, and this was
very stupid of me. The great solid bladder-like swellings almost on the
surface are wonderful objects, but are not the true bladders. These I
found on the roots near the surface, and down to a depth of two inches
in the sand. They are as transparent as glass, from 1/20 to 1/100 of
an inch in size, and hollow. They have all the important points of
structure of the bladders of the floating English species, and I felt
confident I should find captured prey. And so I have to my delight in
two bladders, with clear proof that they had absorbed food from the
decaying mass. For Utricularia is a carrion-feeder, and not strictly
carnivorous like Drosera.
The great solid bladder-like bodies, I believe, are reservoirs of water
like a camel's stomach. As soon as I have made a few more observations,
I mean to be so cruel as to give your plant no water, and observe
whether the great bladders shrink and contain air instead of water; I
shall then also wash all earth from all roots, and see whether there are
true bladders for capturing subterranean insects down to the very bottom
of the pot. Now shall you think me very greedy, if I say that supposing
the species is not very precious, and you have several, will you give
me one more plant, and if so, please to send it to "Orpington Station,
S.E.R., to be forwarded by foot messenger."
I have hardly ever enjoyed a day more in my life than I have this day's
work; and this I owe to your Ladyship's great kindness.
The seeds are very curious monsters; I fancy of some plant allied to
Medicago, but I will show them to Dr. Hooker.
Your ladyship's very gratefully, CH. DARWIN.
CHARLES DARWIN TO J.D. HOOKER. Down, September 30, 1874.
My dear H.,
Your magnificent present of Aldrovanda has arrived quite safe. I have
enjoyed greatly a good look at the shut leaves, one of which I cut open.
It is an aquatic Dionaea, which has acquired some structures identical
with those of Utricularia!
If the leaves open and I can transfer them open under the microscope, I
will try some experiments, for mortal man cannot resist the temptation.
If I cannot transfer, I will do nothing, for otherwise it would require
hundreds of leaves.
You are a good man to give me such pleasure.
Yours affectionately, C. DARWIN.
[The manuscript of 'Insectivorous Plants' was finished in March 1875.
He seems to have been more than usually oppressed by the writing of this
book, thus he wrote to Sir J.D. Hooker in February:--
"You ask about my book, and all that I can say is that I am ready to
commit suicide; I thought it was decently written, but find so much
wants rewriting, that it will not be ready to go to printers for two
months, and will then make a confoundedly big book. Murray will say that
it is no use publishing in the middle of summer, so I do not know what
will be the upshot; but I begin to think that every one who publishes a
book is a fool."
The book was published on July 2nd, 1875, and 2700 copies were sold out
of the edition of 3000.]