CHAPTER 2.XIV.
THE 'POWER OF MOVEMENT IN PLANTS.'
1880.
[The few sentences in the autobiographical chapter give with sufficient
clearness the connection between the 'Power of Movement,' and one of the
author's earlier books, that on 'Climbing Plants.' The central idea of the
book is that the movements of plants in relation to light, gravitation,
etc., are modifications of a spontaneous tendency to revolve or
circumnutate, which is widely inherent in the growing parts of plants.
This conception has not been generally adopted, and has not taken a place
among the canons of orthodox physiology. The book has been treated by
Professor Sachs with a few words of professorial contempt; and by Professor
Wiesner it has been honoured by careful and generously expressed criticism.
Mr. Thiselton Dyer ('Charles Darwin' ('Nature' Series), page 41.) has well
said: "Whether this masterly conception of the unity of what has hitherto
seemed a chaos of unrelated phenomena will be sustained, time alone will
show. But no one can doubt the importance of what Mr. Darwin has done, in
showing that for the future the phenomena of plant movement can and indeed
must be studied from a single point of view."
The work was begun in the summer of 1877, after the publication of
'Different Forms of Flowers,' and by the autumn his enthusiasm for the
subject was thoroughly established, and he wrote to Mr. Dyer: "I am all on
fire at the work." At this time he was studying the movements of
cotyledons, in which the sleep of plants is to be observed in its simplest
form; in the following spring he was trying to discover what useful purpose
these sleep-movements could serve, and wrote to Sir Joseph Hooker (March
25th, 1878):--
"I think we have PROVED that the sleep of plants is to lessen the injury to
the leaves from radiation. This has interested me much, and has cost us
great labour, as it has been a problem since the time of Linnaeus. But we
have killed or badly injured a multitude of plants: N.B.--Oxalis carnosa
was most valuable, but last night was killed."
His letters of this period do not give any connected account of the
progress of the work. The two following are given as being characteristic
of the author:]
CHARLES DARWIN TO W. THISELTON DYER.
Down, June 2, 1878.
My dear Dyer,
I remember saying that I should die a disgraced man if I did not observe a
seedling Cactus and Cycas, and you have saved me from this horrible fate,
as they move splendidly and normally. But I have two questions to ask:
the Cycas observed was a huge seed in a broad and very shallow pot with
cocoa-nut fibre as I suppose. It was named only Cycas. Was it Cycas
pectinata? I suppose that I cannot be wrong in believing that what first
appears above ground is a true leaf, for I can see no stem or axis.
Lastly, you may remember that I said that we could not raise Opuntia
nigricans; now I must confess to a piece of stupidity; one did come up, but
my gardener and self stared at it, and concluded that it could not be a
seedling Opuntia, but now that I have seen one of O. basilaris, I am sure
it was; I observed it only casually, and saw movements, which makes me wish
to observe carefully another. If you have any fruit, will Mr. Lynch (Mr.
R.I. Lynch, now Curator of the Botanic Garden at Cambridge was at this time
in the Royal Gardens, Kew.) be so kind as to send one more?
I am working away like a slave at radicles [roots] and at movements of true
leaves, for I have pretty well done with cotyledons...
That was an EXCELLENT letter about the Gardens (This refers to an attempt
to induce the Government to open the Royal Gardens at Kew in the morning.):
I had hoped that the agitation was over. Politicians are a poor truckling
lot, for [they] must see the wretched effects of keeping the gardens open
all day long.
Your ever troublesome friend,
CH. DARWIN.
CHARLES DARWIN TO W. THISELTON DYER.
4 Bryanston St., Portman Square,
November 21 [1878].
My dear Dyer,
I must thank you for all the wonderful trouble which you have taken about
the seeds of Impatiens, and on scores of other occasions. It in truth
makes me feel ashamed of myself, and I cannot help thinking: "Oh Lord,
when he sees our book he will cry out, is this all for which I have helped
so much!" In seriousness, I hope that we have made out some points, but I
fear that we have done very little for the labour which we have expended on
our work. We are here for a week for a little rest, which I needed.
If I remember right, November 30th, is the anniversary at the Royal, and I
fear Sir Joseph must be almost at the last gasp. I shall be glad when he
is no longer President.
Yours very sincerely,
CH. DARWIN.
[In the spring of the following year, 1879. When he was engaged in putting
his results together, he wrote somewhat despondingly to Mr. Dyer: "I am
overwhelmed with my notes, and almost too old to undertake the job which I
have in hand--i.e. movements of all kinds. Yet it is worse to be idle."
Later on in the year, when the work was approaching completion, he wrote to
Prof. Carus (July 17, 1879), with respect to a translation:--
"Together with my son Francis, I am preparing a rather large volume on the
general movements of Plants, and I think that we have made out a good many
new points and views.
"I fear that our views will meet a good deal of opposition in Germany; but
we have been working very hard for some years at the subject.
"I shall be MUCH pleased if you think the book worth translating, and
proof-sheets shall be sent you, whenever they are ready."
In the autumn he was hard at work on the manuscript, and wrote to Dr. Gray
(October 24, 1879):--
"I have written a rather big book--more is the pity--on the movements of
plants, and I am now just beginning to go over the MS. for the second time,
which is a horrid bore."
Only the concluding part of the next letter refers to the 'Power of
Movements':]
CHARLES DARWIN TO A. DE CANDOLLE.
May 28, 1880.
My dear Sir,
I am particularly obliged to you for having so kindly send me your
'Phytographie' (A book on the methods of botanical research, more
especially of systematic work.); for if I had merely seen it advertised, I
should not have supposed that it could have concerned me. As it is, I have
read with very great interest about a quarter, but will not delay longer
thanking you. All that you say seems to me very clear and convincing, and
as in all your writings I find a large number of philosophical remarks new
to me, and no doubt shall find many more. They have recalled many a puzzle
through which I passed when monographing the Cirripedia; and your book in
those days would have been quite invaluable to me. It has pleased me to
find that I have always followed your plan of making notes on separate
pieces of paper; I keep several scores of large portfolios, arranged on
very thin shelves about two inches apart, fastened to the walls of my
study, and each shelf has its proper name or title; and I can thus put at
once every memorandum into its proper place. Your book will, I am sure, be
very useful to many young students, and I shall beg my son Francis (who
intends to devote himself to the physiology of plants) to read it
carefully.
As for myself I am taking a fortnight's rest, after sending a pile of MS.
to the printers, and it was a piece of good fortune that your book arrived
as I was getting into my carriage, for I wanted something to read whilst
away from home. My MS. relates to the movements of plants, and I think
that I have succeeded in showing that all the more important great classes
of movements are due to the modification of a kind of movement common to
all parts of all plants from their earliest youth.
Pray give my kind remembrances to your son, and with my highest respect and
best thanks,
Believe me, my dear Sir, yours very sincerely,
CHARLES DARWIN.
P.S.--It always pleases me to exalt plants in the organic scale, and if you
will take the trouble to read my last chapter when my book (which will be
sadly too big) is published and sent to you, I hope and think that you also
will admire some of the beautiful adaptations by which seedling plants are
enabled to perform their proper functions.
[The book was published on November 6, 1880, and 1500 copies were disposed
of at Mr. Murray's sale. With regard to it he wrote to Sir J.D. Hooker
(November 23):--
"Your note has pleased me much--for I did not expect that you would have
had time to read ANY of it. Read the last chapter, and you will know the
whole result, but without the evidence. The case, however, of radicles
bending after exposure for an hour to geotropism, with their tips (or
brains) cut off is, I think, worth your reading (bottom of page 525); it
astounded me. The next most remarkable fact, as it appeared to me (page
148), is the discrimination of the tip of the radicle between a slightly
harder and softer object affixed on opposite sides of tip. But I will
bother you no more about my book. The sensitiveness of seedlings to light
is marvellous."
To another friend, Mr. Thiselton Dyer, he wrote (November 28, 1880):--
"Very many thanks for your most kind note, but you think too highly of our
work, not but what this is very pleasant...Many of the Germans are very
contemptuous about making out the 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."
The book was widely reviewed, and excited much interest among the general
public. The following letter refers to a leading article in the "Times",
November 20, 1880:]
CHARLES DARWIN TO MRS. HALIBURTON. (Mrs. Haliburton was a daughter of my
father's early friend, the late Mr. Owen, of Woodhouse.)
Down, November 22, 1880.
My dear Sarah,
You see how audaciously I begin; but I have always loved and shall ever
love this name. Your letter has done more than please me, for its kindness
has touched my heart. I often think of old days and of the delight of my
visits to Woodhouse, and of the deep debt of gratitude I owe to your
father. It was very good of you to write. I had quite forgotten my old
ambition about the Shrewsbury newspaper (Mrs. Haliburton had reminded him
of his saying as a boy that if Eddowes' newspaper ever alluded to him as
"our deserving fellow-townsman," his ambition would be amply gratified.);
but I remember the pride which I felt when I saw in a book about beetles
the impressive words "captured by C. Darwin." Captured sounded so grand
compared with caught. This seemed to me glory enough for any man! I do
not know in the least what made the "Times" glorify me (The following is
the opening sentence of the leading article:--"Of all our living men of
science none have laboured longer and to more splendid purpose than Mr.
Darwin."), for it has sometimes pitched into me ferociously.
I should very much like to see you again, but you would find a visit here
very dull, for we feel very old and have no amusement, and lead a solitary
life. But we intend in a few weeks to spend a few days in London, and then
if you have anything else to do in London, you would perhaps come and lunch
with us. (My father had the pleasure of seeing Mrs. Haliburton at his
brother's house in Queen Anne Street.)
Believe me, my dear Sarah,
Yours gratefully and affectionately,
CHARLES DARWIN.
[The following letter was called forth by the publication of a volume
devoted to the criticism of the 'Power of Movement in Plants' by an
accomplished botanist, Dr. Julius Wiesner, Professor of Botany in the
University of Vienna:]
CHARLES DARWIN TO JULIUS WIESNER.
Down, October 25th, 1881.
My dear Sir,
I have now finished your book ('Das Bewegungsvermogen der Pflanzen.'
Vienna, 1881.), and have understood the whole except a very few passages.
In the first place, let me thank you cordially for the manner in which you
have everywhere treated me. You have shown how a man may differ from
another in the most decided manner, and yet express his difference with the
most perfect courtesy. Not a few English and German naturalists might
learn a useful lesson from your example; for the coarse language often used
by scientific men towards each other does no good, and only degrades
science.
I have been profoundly interested by your book, and some of your
experiments are so beautiful, that I actually felt pleasure while being
vivisected. It would take up too much space to discuss all the important
topics in your book. I fear that you have quite upset the interpretation
which I have given of the effects of cutting off the tips of horizontally
extended roots, and of those laterally exposed to moisture; but I cannot
persuade myself that the horizontal position of lateral branches and roots
is due simply to their lessened power of growth. Nor when I think of my
experiments with the cotyledons of Phalaris, can I give up the belief of
the transmission of some stimulus due to light from the upper to the lower
part. At page 60 you have misunderstood my meaning, when you say that I
believe that the effects from light are transmitted to a part which is not
itself heliotropic. I never considered whether or not the short part
beneath the ground was heliotropic; but I believe that with young seedlings
the part which bends NEAR, but ABOVE the ground is heliotropic, and I
believe so from this part bending only moderately when the light is
oblique, and bending rectangularly when the light is horizontal.
Nevertheless the bending of this lower part, as I conclude from my
experiments with opaque caps, is influenced by the action of light on the
upper part. My opinion, however, on the above and many other points,
signifies very little, for I have no doubt that your book will convince
most botanists that I am wrong in all the points on which we differ.
Independently of the question of transmission, my mind is so full of facts
leading me to believe that light, gravity, etc., act not in a direct manner
on growth, but as stimuli, that I am quite unable to modify my judgment on
this head. I could not understand the passage at page 78, until I
consulted my son George, who is a mathematician. He supposes that your
objection is founded on the diffused light from the lamp illuminating both
sides of the object, and not being reduced, with increasing distance in the
same ratio as the direct light; but he doubts whether this NECESSARY
correction will account for the very little difference in the heliotropic
curvature of the plants in the successive pots.
With respect to the sensitiveness of the tips of roots to contact, I cannot
admit your view until it is proved that I am in error about bits of card
attached by liquid gum causing movement; whereas no movement was caused if
the card remained separated from the tip by a layer of the liquid gum. The
fact also of thicker and thinner bits of card attached on opposite sides of
the same root by shellac, causing movement in one direction, has to be
explained. You often speak of the tip having been injured; but externally
there was no sign of injury: and when the tip was plainly injured, the
extreme part became curved TOWARDS the injured side. I can no more believe
that the tip was injured by the bits of card, at least when attached by
gum-water, than that the glands of Drosera are injured by a particle of
thread or hair placed on it, or that the human tongue [is so] when it feels
any such object.
About the most important subject in my book, namely circumnutation, I can
only say that I feel utterly bewildered at the difference in our
conclusions; but I could not fully understand some parts which my son
Francis will be able to translate to me when he returns home. The greater
part of your book is beautifully clear.
Finally, I wish that I had enough strength and spirit to commence a fresh
set of experiments, and publish the results, with a full recantation of my
errors when convinced of them; but I am too old for such an undertaking,
nor do I suppose that I shall be able to do much, or any more, original
work. I imagine that I see one possible source of error in your beautiful
experiment of a plant rotating and exposed to a lateral light.
With high respect and with sincere thanks for the kind manner in which you
have treated me and my mistakes, I remain, my dear Sir, yours sincerely,
CHARLES DARWIN.
