I have been looking at the fertilisation of wheat, and I think possibly

you might find something curious. I observed in almost every one of

the pollen-grains, which had become empty and adhered to (I suppose the

viscid) branching hairs of the stigma, that the pollen-tube was always

(?) emitted on opposite side of grain to that in contact with the branch

of the stigma. This seems very odd. The branches of the stigma are

very thin, formed apparently of three rows of cells of hardly greater

diameter than pollen-tube. I am astonished that the tubes should be able

to penetrate the walls. The specimens examined (not carefully by me)

had pollen only during few hours on stigma; and the mere SUSPICION has

crossed me that the pollen-tubes crawl down these branches to the base

and then penetrate the stigmatic tissue. (619/1. See Strasburger's "Neue

Untersuchungen uber den Befruchtungsvorgang bei den Phanerogamen," 1884.

In Alopecurus pratensis he describes the pollen as adhering to the end

of a projection from the stigma where it germinates; the tube crawls

along or spirally round this projection until it reaches the angle where

the stigmatic branch is given off; here it makes an entrance and travels

in the middle lamella between two cells.) The paleae open for a

short period for stigma to be dusted, and then close again, and such

travelling down would take place under protection. High powers and good

adjustment are necessary. Ears expel anthers when kept in water in room;

but the paleae apparently do not open and expose stigma; but the stigma

could easily be artificially impregnated.

If I were you I would keep memoranda of points worth attending to.

2.X.II. MELASTOMACEAE, 1862-1881.

(620/1. The following series of letters (620-630) refers to the

Melastomaceae and certain other flowers of analogous form. In 1862

Darwin attempted to explain the existence of two very different sets of

stamens in these plants as a case of dimorphism, somewhat analogous to

the state of things in Primula. In this view he was probably wrong,

but this does not diminish the interest of the crossing experiments

described in the letters. The persistence of his interest in this part

of the subject is shown in the following passage from his Preface to the

English translation of H. Muller's "Befruchtung der Blumen"; the passage

is dated February, 1882, but was not published until the following year.

"There exist also some few plants the flowers of which include two sets

of stamens, differing in the shape of the anthers and in the colour of

the pollen; and at present no one knows whether this difference has

any functional significance, and this is a point which ought to be

determined."

It is not obvious why he spoke of the problem as if no light had been

thrown on it, since in 1881 Fritz Muller had privately (see Letter 629)

offered an explanation which Darwin was strongly inclined to accept.

(620/2. H. Muller published ("Nature," August 4th, 1881) a letter

from his brother Fritz giving the theory in question for Heeria. Todd

("American Naturalist," April 1882), described a similar state of things

in Solanum rostratum and in Cassia: and H.O. Forbes ("Nature," August

1882, page 386) has done the same for Melastoma. In Rhexia virginica Mr.

W.H. Leggett ("Bulletin Torrey Bot. Club, New York," VIII., 1881, page

102) describes the curious structure of the anther, which consists of

two inflated portions and a tubular part connecting the two. By pressing

with a blunt instrument on one of the ends, the pollen is forced out

in a jet through a fine pore in the other inflated end. Mr. Leggett has

seen bees treading on the anthers, but could not get near enough to

see the pollen expelled. In the same journal, Volume IX., page 11,

Mr. Bailey describes how in Heterocentron roseum, "upon pressing the

bellows-like anther with a blunt pencil, the pollen was ejected to

a full inch in distance." On Lagerstroemia as comparable with the

Melastomads see Letter 689.) Fritz Muller's theory with regard to

the Melastomads and a number of analogous cases in other genera are

discussed in H. Muller's article in "Kosmos" (620/3. "Kosmos," XIII.,

1883, page 241.), where the literature is given. F. Muller's theory is

that in Heeria the yellow anthers serve merely as a means of attracting

pollen-collecting bees, while the longer stamens with purple or crimson

anthers supply pollen for fertilising purposes. If Muller is right the

pollen from the yellow anthers would not normally reach the stigma. The

increased vigour observed in the seedlings from the yellow anthers

would seem to resemble the good effect of a cross between different

individuals of the same species as worked out in "Cross and Self

Fertilisation," for it is difficult to believe that the pollen of the

purple anthers has become, by adaptation, less effective than that

of the yellow anthers. In the letters here given there is some

contradiction between the statements as to the position of the two

sets of stamens in relation to the sepals. According to Eichler

("Bluthendiagramme, II., page 482) the longer stamens may be either

epipetalous or episepalous in this family.

The work on the Melastomads is of such intrinsic importance that we have

thought it right to give the correspondence in considerable detail; we

have done so in spite of the fact that Darwin arrived at no

definite conclusion, and in spite of an element of confusion and

unsatisfactoriness in the series of letters. This applies also to Letter

629, written after Darwin had learned Fritz Muller's theory, which is

obscured by some errors or slips of the pen.)

LETTER 620. TO G. BENTHAM. Down, February 3rd [1862?]

As you so kindly helped me before on dimorphism, will you forgive me

begging for a little further information, if in your power to give it?

The case is that of the Melastomads with eight stamens, on which I have

been experimenting. I am perplexed by opposed statements: Lindley says

the stamens which face the petals are sterile; Wallich says in Oxyspora

paniculata that the stamens which face the sepals are destitute of

pollen; I find plenty of apparently good pollen in both sets of stamens

in Heterocentron [Heeria], Monochoetum, and Centradenia. Can you throw

any light on this? But there is another point on which I am more anxious

for information. Please look at the enclosed miserable diagram. I find

that the pollen of the yellow petal-facing stamens produce more than

twice as much seed as the pollen of the purple sepal-facing stamens.

This is exactly opposed to Lindley's statement--viz., that the

petal-facing stamens are sterile. But I cannot at present believe that

the case has any relation to abortion; it is hardly possible to believe

that the longer and very curious stamens, which face the sepals in

this Heterocentron, are tending to be rudimentary, though their

pollen applied to their own flowers produces so much less seed. It is

conformable with what we see in Primula that the [purple] sepal-facing

anthers, which in the plant seen by me stood quite close on each side

of the stigma, should have been rendered less fitted to fertilise the

stigma than the stamens on the opposite side of the flower. Hence the

suspicion has crossed me that if many plants of the Heterocentron roseum

were examined, half would be found with the pistil nearly upright,

instead of being rectangularly bent down, as shown in the diagram

(620/4. According to Willis, "Flowering Plants and Ferns," 1897, Volume

II., page 252, the style in Monochoetum, "at first bent downwards, moves

slowly up till horizontal."); or, if the position of pistil is fixed,

that in half the plants the petal-facing stamens would bend down, and in

the other half of the plants the sepal-facing stamens would bend down as

in the diagram. I suspect the former case, as in Centradenia I find the

pistil nearly straight. Can you tell me? (620/5. No reply by Mr.

Bentham to this or the following queries has been found.) Can the name

Heterocentron have any reference to such diversity? Would it be

asking too great a favour to ask you to look at dried specimens of

Heterocentron roseum (which would be best), or of Monochoetum, or any

eight-stamened Melastomad, of which you have specimens from several

localities (as this would ensure specimens having been taken from

distinct plants), and observe whether the pistil bends differently or

stamens differently in different plants? You will at once see that, if

such were the fact, it would be a new form of dimorphism, and would open

up a large field of inquiry with respect to the potency of the pollen in

all plants which have two sets of stamens--viz., longer and shorter. Can

you forgive me for troubling you at such unreasonable length? But it is

such waste of time to experiment without some guiding light. I do not

know whether you have attended particularly to Melastoma; if you

have not, perhaps Hooker or Oliver may have done so. I should be very

grateful for any information, as it will guide future experiments.

P.S.--Do you happen to know, when there are only four stamens, whether

it is the petal or sepal-facers which are preserved? and whether in the

four-stamened forms the pistil is rectangularly bent or is straight?

LETTER 621. TO ASA GRAY. Down, February 16th [1862?].

I have been trying a few experiments on Melastomads; and they seem to

indicate that the pollen of the two curious sets of anthers (i.e. the

petal-facers and the sepal-facers) have very different powers; and it

does not seem that the difference is connected with any tendency to

abortion in the one set. Now I think I can understand the structure of

the flower and means of fertilisation, if there be two forms,--one with

the pistil bent rectangularly out of the flower, and the other with it

nearly straight.

Our hot-house and green-house plants have probably all descended by

cuttings from a single plant of each species; so I can make out nothing

from them. I applied in vain to Bentham and Hooker; but Oliver picked

out some sentences from Naudin, which seem to indicate differences in

the position of the pistil.

I see that Rhexia grows in Massachusetts; and I suppose has two

different sets of stamens. Now, if in your power, would you observe the

position of the pistil in different plants, in lately opened flowers

of the same age? (I specify this because in Monochaetum I find great

changes of position in the pistils and stamens, as flower gets old).

Supposing that my prophecy should turn out right, please observe whether

in both forms the passage into the flower is not [on] the upper side

of the pistil, owing to the basal part of the pistil lying close to the

ring of filaments on the under side of the flower. Also I should like to

know the colour of the two sets of anthers. This would take you only a

few minutes, and is the only way I see that I can find out whether these

plants are dimorphic in this peculiar way--i.e., only in the position

of the pistil (621/1. In Exacum and in Saintpaulia the flowers are

dimorphic in this sense: the style projects to either the right or the

left side of the corolla, from which it follows that a right-handed

flower would fertilise a left-handed one, and vice versa. See Willis,

"Flowering Plants and Ferns," 1897, Volume I., page 73.) and in its

relation to the two kinds of pollen. I am anxious about this, because if

it should prove so, it will show that all plants with longer and shorter

or otherwise different anthers will have to be examined for dimorphism.

LETTER 622. TO ASA GRAY. March 15th [1862].

...I wrote some little time ago about Rhexia; since then I have been

carefully watching and experimenting on another genus, Monochaetum; and

I find that the pistil is first bent rectangularly (as in the sketch

sent), and then in a few days becomes straight: the stamens also move.

If there be not two forms of Rhexia, will you compare the position of

the part in young and old flowers? I have a suspicion (perhaps it will

be proved wrong when the seed-capsules are ripe) that one set of anthers

are adapted to the pistil in early state, and the other set for it

in its later state. If bees visit the Rhexia, for Heaven's sake watch

exactly how the anther and stigma strike them, both in old and young

flowers, and give me a sketch.

Again I say, do not hate me.

LETTER 623. TO J.D. HOOKER. Leith Hill Place, Dorking, Thursday, 15th

[May 1862].

You stated at the Linnean Society that different sets of seedling

Cinchona (623/1. Cinchona is apparently heterostyled: see "Forms of

Flowers," Edition II., page 134.) grew at very different rate, and from

my Primula case you attributed it probably to two sorts of pollen. I

confess I thought you rash, but I now believe you were quite right.

I find the yellow and crimson anthers of the same flower in the

Melastomatous Heterocentron roseum have different powers; the yellow

producing on the same plant thrice as many seeds as the crimson anthers.

I got my neighbour's most skilful gardener to sow both kinds of seeds,

and yesterday he came to me and said it is a most extraordinary thing

that though both lots have been treated exactly alike, one lot all

remain dwarfs and the other lot are all rising high up. The dwarfs were

produced by the pollen of the crimson anthers. In Monochaetum ensiferum

the facts are more complex and still more strange; as the age and

position of the pistils comes into play, in relation to the two kinds of

pollen. These facts seem to me so curious that I do not scruple to ask

you to see whether you can lend me any Melastomad just before flowering,

with a not very small flower, and which will endure for a short time a

greenhouse or sitting-room; when fertilised and watered I could send it

to Mr. Turnbull's to a cool stove to mature seed. I fully believe the

case is worth investigation.

P.S.--You will not have time at present to read my orchid book; I never

before felt half so doubtful about anything which I published. When you

read it, do not fear "punishing" me if I deserve it.

Adios. I am come here to rest, which I much want.

Whenever you have occasion to write, pray tell me whether you have

Rhododendron Boothii from Bhootan, with a smallish yellow flower,

and pistil bent the wrong way; if so, I would ask Oliver to look for

nectary, for it is an abominable error of Nature that must be corrected.

I could hardly believe my eyes when I saw the pistil.

LETTER 624. TO ASA GRAY. January 19th [1863].

I have been at those confounded Melastomads again; throwing good money

(i.e. time) after bad. Do you remember telling me you could see no

nectar in your Rhexia? well, I can find none in Monochaetum, and Bates

tells me that the flowers are in the most marked manner neglected by

bees and lepidoptera in Amazonia. Now the curious projections or horns

to the stamens of Monochaetum are full of fluid, and the suspicion

occurs to me that diptera or small hymenoptera may puncture these horns

like they puncture (proved since my orchid book was published) the dry

nectaries of true Orchis. I forget whether Rhexia is common; but I very

much wish you would next summer watch on a warm day a group of flowers,

and see whether they are visited by small insects, and what they do.

LETTER 625. TO I.A. HENRY. Down, January 20th [1863].

...You must kindly permit me to mention any point on which I want

information. If you are so inclined, I am curious to know from

systematic experiments whether Mr. D. Beaton's statement that the pollen

of two shortest anthers of scarlet Pelargonium produce dwarf plants

(625/1. See "Animals and Plants," Edition II., Volume II., page 150, for

a brief account of Darwin's experiments on this genus. Also loc. cit.,

page 338 (note), for a suggested experiment.), in comparison with plants

produced from the same mother-plant by the pollen of longer stamens from

the same flower. It would aid me much in some laborious experiments on

Melastomads. I confess I feel a little doubtful; at least, I feel pretty

nearly sure that I know the meaning of short stamens in most plants.

This summer (for another object) I crossed Queen of Scarlet Pelargonium

with pollen of long and short stamens of multiflora alba, and it so

turns out that plants from short stamens are the tallest; but I believe

this to have been mere chance. My few crosses in Pelargonium were made

to get seed from the central peloric or regular flower (I have got one

from peloric flower by pollen of peloric), and this leads me to suggest

that it would be very interesting to test fertility of peloric flowers

in three ways,--own peloric pollen on peloric stigma, common pollen

on peloric stigma, peloric pollen on common stigma of same species. My

object is to discover whether with change of structure of flower there

is any change in fertility of pollen or of female organs. This might

also be tested by trying peloric and common pollen on stigma of a

distinct species, and conversely. I believe there is a peloric and

common variety of Tropaeolum, and a peloric or upright and common

variation of some species of Gloxinia, and the medial peloric flowers of

Pelargonium, and probably others unknown to me.

LETTER 626. TO I.A. HENRY. Hartfield, May 2nd [1863].

In scarlet dwarf Pelargonium, you will find occasionally an additional

and abnormal stamen on opposite and lower side of flower. Now the pollen

of this one occasional short stamen, I think, very likely would produce

dwarf plants. If you experiment on Pelargonium I would suggest your

looking out for this single stamen.

I observed fluctuations in length of pistil in Phloxes, but thought it

was mere variability.

If you could raise a bed of seedling Phloxes of any species except

P. Drummondii, it would be highly desirable to see if two forms are

presented, and I should be very grateful for information and flowers for

inspection. I cannot remember, but I know that I had some reason to look

after Phloxes. (626/1. See "Forms of Flowers," Edition II., page 119,

where the conjecture is hazarded that Phlox subulata shows traces of a

former heterostyled condition.)

I do not know whether you have used microscopes much yet. It adds

immensely to interest of all such work as ours, and is indeed

indispensable for much work. Experience, however, has fully convinced me

that the use of the compound without the simple microscope is absolutely

injurious to progress of N[atural] History (excepting, of course, with

Infusoria). I have, as yet, found no exception to the rule, that when a

man has told me he works with the compound alone his work is valueless.

LETTER 627. TO ASA GRAY. March 20th [1863].

I wrote to him [Dr. H. Cruger, of Trinidad] to ask him to observe what

the insects did in the flowers of Melastomaceae: he says not proper

season yet, but that on one species a small bee seemed busy about the

horn-like appendages to the anthers. It will be too good luck if

my study of the flowers in the greenhouse has led me to right

interpretation of these appendages.

LETTER 628. TO J.D. HOOKER. Down, November 28th [1871].

If you had come here on Sunday I should have asked you whether you could

give me seed or seedlings of any Melastomad which would flower soon to

experiment on! I wrote also to J. Scott to ask if he could give me seed.

Several years ago I raised a lot of seedlings of a Melastomad greenhouse

bush (Monochaetus or some such name) (628/1. Monochaetum.) from stigmas

fertilised separately by the two kinds of pollen, and the seedlings

differed remarkably in size, and whilst young, in appearance; and I

never knew what to think of the case (so you must not use it), and

have always wished to try again, but they are troublesome beasts to

fertilise.

On the other hand I could detect no difference in the product from

the two coloured anthers of Clarkia. (628/2. Clarkia has eight stamens

divided into two groups which differ in the colour of the anthers.) If

you want to know further particulars of my experiments on Monochaetum

(?) and Clarkia, I will hunt for my notes. You ask about difference in

pollen in the same species. All dimorphic and trimorphic plants present

such difference in function and in size. Lythrum and the trimorphic

Oxalis are the most wonderful cases. The pollen of the closed imperfect

cleistogamic flowers differ in the transparency of the integument, and

I think in size. The latter point I could ascertain from my notes. The

pollen or female organs must differ in almost every individual in some

manner; otherwise the pollen of varieties and even distinct individuals

of same varieties would not be so prepotent over the individual plant's

own pollen. Here follows a case of individual differences in function of

pollen or ovules or both. Some few individuals of Reseda odorata and R.

lutea cannot be fertilised, or only very rarely, by pollen of the same

plant, but can by pollen of any other individual. I chanced to have two

plants of R. odorata in this state; so I crossed them and raised five

seedlings, all of which were self sterile and all perfectly fertile

with pollen of any other individual mignonette. So I made a self sterile

race! I do not know whether these are the kinds of facts which you

require.

Think whether you can help me to seed or better seedlings (not cuttings)

of any Melastomad.

LETTER 629. TO F. MULLER. Down, March 20th, 1881.

I have received the seeds and your most interesting letter of February

7th. The seeds shall be sown, and I shall like to see the plants

sleeping; but I doubt whether I shall make any more detailed

observations on this subject, as, now that I feel very old, I require

the stimulus of some novelty to make me work. This stimulus you

have amply given me in your remarkable view of the meaning of the

two-coloured stamens in many flowers. I was so much struck with this

fact with Lythrum, that I began experimenting on some Melastomaceae,

which have two sets of extremely differently coloured anthers. After

reading your letter I turned to my notes (made 20 years ago!) to see

whether they would support or contradict your suggestion. I cannot tell

yet, but I have come across one very remarkable result, that seedlings

from the crimson anthers were not 11/20ths of the size of seedlings from

the yellow anthers of the same flowers. Fewer good seeds were produced

by the crimson pollen. I concluded that the shorter stamens were

aborting, and that the pollen was not good. (629/1. "Shorter stamens"

seems to be a slip of the pen for "longer,"--unless the observations

were made on some genus in which the structure is unusual.) The mature

pollen is incoherent, and must be [word illegible] against the visiting

insect's body. I remembered this, and I find it said in my EARLY

notes that bees would never visit the flowers for pollen. This made

me afterwards write to the late Dr. Cruger in the West Indies, and he

observed for me the flowers, and saw bees pressing the anthers with

their mandibles from the base upwards, and this forced a worm-like

thread of pollen from the terminal pore, and this pollen the bees

collected with their hind legs. So that the Melastomads are not opposed

to your views.

I am now working on the habits of worms, and it tires me much to change

my subject; so I will lay on one side your letter and my notes, until I

have a week's leisure, and will then see whether my facts bear on your

views. I will then send a letter to "Nature" or to the Linn. Soc., with

the extract of your letter (and this ought to appear in any case), with

my own observations, if they appear worth publishing. The subject had

gone out of my mind, but I now remember thinking that the imperfect

action of the crimson stamens might throw light on hybridism. If this

pollen is developed, according to your view, for the sake of attracting

insects, it might act imperfectly, as well as if the stamens were

becoming rudimentary. (629/2. As far as it is possible to understand the

earlier letters it seems that the pollen of the shorter stamens, which

are adapted for attracting insects, is the most effective.) I do not

know whether I have made myself intelligible.

LETTER 630. TO W. THISELTON-DYER. Down, March 21st [1881].

I have had a letter from Fritz Muller suggesting a novel and very

curious explanation of certain plants producing two sets of anthers

of different colour. This has set me on fire to renew the laborious

experiments which I made on this subject, now 20 years ago. Now, will

you be so kind as to turn in your much worked and much holding head,

whether you can think of any plants, especially annuals, producing

2 such sets of anthers. I believe that this is the case with Clarkia

elegans, and I have just written to Thompson for seeds. The Lythraceae

must be excluded, as these are heterostyled.

I have got seeds from Dr. King of some Melastomaceae, and will write

to Veitch to see if I can get the Melastomaceous genera Monochaetum and

Heterocentron or some such name, on which I before experimented. Now,

if you can aid me, I know that you will; but if you cannot, do not write

and trouble yourself.

2.X.III. CORRESPONDENCE WITH JOHN SCOTT, 1862-1871.

"If he had leisure he would make a wonderful observer, to my judgment;

I have come across no one like him."--Letter to J.D. Hooker, May 29th

[1863].

(631/1. The following group of letters to John Scott, of whom some

account is given elsewhere (Volume I., Letters 150 and 151, and Index.)

deal chiefly with experimental work in the fertilisation of flowers. In

addition to their scientific importance, several of the letters are

of special interest as illustrating the encouragement and friendly

assistance which Darwin gave to his correspondent.)

LETTER 631. JOHN SCOTT TO CHARLES DARWIN. Edinburgh Botanic Gardens,

November 11th, 1862.

I take the liberty of addressing you for the purpose of directing your

attention to an error in one of your ingenious explanations of the

structural adaptations of the Orchidaceae in your late work. This occurs

in the genus Acropera, two species of which you assume to be unisexual,

and so far as known represented by male individuals only. Theoretically

you have no doubt assigned good grounds for this view; nevertheless,

experimental observations that I am now making have already convinced me

of its fallacy. And I thus hurriedly, and as you may think prematurely,

direct your attention to it, before I have seen the final result of my

own experiment, that you might have the longer time for reconsidering

the structure of this genus for another edition of your interesting

book, if indeed it be not already called for. I am furthermore induced

to communicate the results of my yet imperfect experiments in the belief

that the actuating principle of your late work is the elicitation of

truth, and that you will gladly avail yourself of this even at the

sacrifice of much ingenious theoretical argumentation.

Since I have had an opportunity of perusing your work on orchid

fertilisation, my attention has been particularly directed to the

curiously constructed floral organs of Acropera. I unfortunately have

as yet had only a few flowers for experimental enquiry, otherwise my

remarks might have been clearer and more satisfactory. Such as they are,

however, I respectfully lay [them] before you, with a full assurance

of their veracity, and I sincerely trust that as such you will receive

them.

Your observations seem to have been chiefly directed to the A. luteola,

mine to the A. Loddigesii, which, however, as you remark, is in a very

similar constructural condition with the former; having the same narrow

stigmatic chamber, abnormally developed placenta, etc. In regard to the

former point--contraction of stigmatic chamber--I may remark that

it does not appear to be absolutely necessary that the pollen-masses

penetrate this chamber for effecting fecundation. Thus a raceme was

produced upon a plant of A. Loddigesii in the Botanic Gardens here

lately; upon this I left only six flowers. These I attempted to

fertilise, but with two only of the six have I been successful: I

succeeded in forcing a single pollen-mass into the stigmatic chamber

of one of the latter, but I failed to do this on the other; however, by

inserting a portion of a pedicel with a pollinium attached, I caused

the latter to adhere, with a gentle press, to the mouth of the stigmatic

chamber. Both of these, as I have already remarked, are nevertheless

fertilised; one of them I have cut off for examination, and its

condition I will presently describe; the other is still upon the plant,

and promises fair to attain maturity. In regard to the other four

flowers, I may remark that though similarly fertilised--part having

pollinia inserted, others merely attached--they all withered and dropped

off without the least swelling of the ovary. Can it be, then, that this

is really an [andro-monoecious] species?--part of the flowers male,

others truly hermaphrodite.

In making longitudinal sections of the fertilised ovary before

mentioned, I found the basal portion entirely destitute of ovules, their

place being substituted by transparent cellular ramification of the

placentae. As I traced the placentae upwards, the ovules appeared,

becoming gradually more abundant towards its apex. A transverse section

near the apex of the ovary, however, still exhibited a more than

ordinary placental development--i.e. [congenitally?] considered--each

end giving off two branches, which meet each other in the centre of the

ovary, the ovules being irregularly and sparingly disposed upon their

surfaces.

In regard to the mere question of fertilisation, then, I am perfectly

satisfied, but there are other points which require further elucidation.

Among these I may particularly refer to the contracted stigmatic

chamber, and the slight viscidity of its disk. The latter, however,

may be a consequence of uncongenial conditions--as you do not mention

particularly its examination by any author in its natural habitat. If

such be the case, the contracted stigmatic chamber will offer no real

difficulty, should the viscous exudations be only sufficient to render

the mouth adhesive. For, as I have already shown, the pollen-tubes may

be emitted in this condition, and effect fecundation without being in

actual contact with the stigmatic surface, as occurs pretty regularly in

the fertilisation of the Stapelias, for example. But, indeed, your

own discovery of the independent germinative capabilities of the

pollen-grains of certain Orchidaceae is sufficiently illustrative of

this.

I may also refer to the peculiar abnormal condition that many at least

of the ovaries present in a comparative examination of the placentae,

and of which I beg to suggest the following explanation, though it is as

yet founded on limited observations. In examining certain young ovaries

of A. Loddigesii, I found some of them filled with the transparent

membranous fringes of more or less distinctly cellular matter, which,

from your description of the ovaries of luteola, appears to differ

simply in the greater development in the former species. Again, in

others I found small mammillary bodies, which appeared to be true

ovules, though I could not perfectly satisfy myself as to the existence

of the micropyle or nucleus. I unfortunately neglected to apply any

chemical test. The fact, however, that in certain of the examined

ovaries few or none of the latter bodies occurred--the placenta alone

being developed in an irregular membranous form, taken in conjunction

with the results of my experiments--before alluded to--on their

fertilisation, leads me to infer that two sexual conditions are

presented by the flowers of this plant. In short, that many of the

ovaries are now normally abortive, though Nature occasionally makes

futile efforts for their perfect development, in the production of

ovuloid bodies; these then I regard as the male flowers. The others that

are still capable of fertilisation, and likewise possessing male

organs, are hermaphrodite, and must, I think, from the results of your

comparative examinations, present a somewhat different condition; as it

can scarcely be supposed that ovules in the condition you describe could

ever be fertilised.

This is at least the most plausible explanation I can offer for the

different results in my experiments on the fertilisation of apparently

similar morphologically constructed flowers; others may, however, occur

to you. Here there is not, as in the Catasetum, any external change

visible in the respective unisexual and bisexual flowers. And yet it

would appear from your researches that the ovules of Acropera are in a

more highly atrophied condition than occurs in Catasetum, though, as

you likewise remark, M. Neumann has never succeeded in fertilising C.

tridentatum. If there be not, then, an arrangement of the reproductive

structures, such as I have indicated, how can the different results in

M. Neumann's experiments and mine be accounted for? However, as you

have examined many flowers of both A. luteola and Loddigesii, such a

difference in the ovulary or placental structures could scarcely

have escaped your observation. But, be this as it may, the--to me at

least--demonstrated fact still remains, that certain flowers of A.

Loddigesii are capable of fertilisation, and that, though there are good

grounds for supposing that important physiological changes are going on

in the sexual phenomena of this species, there is no evidence whatever

for supposing that external morphological changes have so masked certain

individuals as to prevent their recognition.

I would now, sir, in conclusion beg you to excuse me for this

infringement upon your valuable time, as I have been induced to

write you in the belief that you have had negative results from

other experimenters, before you ventured to propose your theoretical

explanation, and consequently that you have been unknowingly led into

error. I will continue, as opportunities present themselves, to examine

the many peculiarities you have pointed out in this as well as others of

the Orchid family; and at present I am looking forward with anxiety for

the maturation of the ovary of A. Loddigesii, which will bear testimony

to the veracity of the remarks I have ventured to lay before you.

LETTER 632. TO J.D. HOOKER. Down, 18th [November 1862].

Strange to say, I have only one little bother for you to-day, and that

is to let me know about what month flowers appear in Acropera Loddigesii

and luteola; for I want extremely to beg a few more flowers, and if I

knew the time I would keep a memorandum to remind you. Why I want these

flowers is (and I am much alarmed) that Mr. J. Scott, of Bot. Garden of

Edinburgh (do you know anything of him?) has written me a very long and

clever letter, in which he confirms most of my observations; but tells

me that with much difficulty he managed to get pollen into orifice, or

as far as mouth of orifice, of six flowers of A. Loddigesii (the ovarium

of which I did not examine), and two pods set; one he gathered, and saw

a very few ovules, as he thinks, on the large and mostly rudimentary

placenta. I shall be most curious to hear whether the other pod produces

a good lot of seed. He says he regrets that he did not test the ovules

with chemical agents: does he mean tincture of iodine? He suggests that

in a state of nature the viscid matter may come to the very surface of

stigmatic chamber, and so pollen-masses need not be inserted. This is

possible, but I should think improbable. Altogether the case is very

odd, and I am very uneasy, for I cannot hope that A. Loddigesii is

hermaphrodite and A. luteola the male of the same species. Whenever I

can get Acropera would be a very good time for me to look at Vanda in

spirits, which you so kindly preserved for me.

LETTER 633. TO J. SCOTT.

(633/1. The following is Darwin's reply to the above letter from Scott.

In the first edition of "Fertilisation of Orchids" (page 209) he assumed

that the sexes in Acropera, as in Catasetum, were separate. In the

second edition (page 172) he writes: "I was, however, soon convinced

of my error by Mr. Scott, who succeeded in artificially fertilising

the flowers with their own pollen. A remarkable discovery by Hildebrand

(633/2. "Bot. Zeitung," 1863 and 1865.), namely, that in many orchids

the ovules are not developed unless the stigma is penetrated by the

pollen-tubes...explains the state of the ovarium in Acropera, as

observed by me." In regard to this subject see Letter 608.)

Down, November 12th, 1862.

I thank you most sincerely for your kindness in writing to me, and for

[your] very interesting letter. Your fact has surprised me greatly, and

has alarmed me not a little, for if I am in error about Acropera I may

be in error about Catasetum. Yet when I call to mind the state of

the placentae in A. luteola, I am astonished that they should produce

ovules. You will see in my book that I state that I did not look at the

ovarium of A. Loddigesii. Would you have the kindness to send me word

which end of the ovarium is meant by apex (that nearest the flower?),

for I must try and get this species from Kew and look at its ovarium.

I shall be extremely curious to hear whether the fruit, which is now

maturing, produces a large number of good and plump seed; perhaps you

may have seen the ripe capsules of other Vandeae, and may be able

to form some conjecture what it ought to produce. In the young,

unfertilised ovaria of many Vandeae there seemed an infinitude of

ovules. In desperation it occurs to me as just possible, as almost

everything in nature goes by gradation, that a properly male flower

might occasionally produce a few seeds, in the same manner as female

plants sometimes produce a little pollen. All your remarks seem to me

excellent and very interesting, and I again thank you for your kindness

in writing to me. I am pleased to observe that my description of the

structure of Acropera seems to agree pretty well with what you have

observed. Does it not strike you as very difficult to understand

how insects remove the pollinia and carry them to the stigmas? Your

suggestion that the mouth of the stigmatic cavity may become charged

with viscid matter and thus secure the pollinia, and that the

pollen-tubes may then protrude, seems very ingenious and new to me; but

it would be very anomalous in orchids, i.e. as far as I have seen. No

doubt, however, though I tried my best, I shall be proved wrong in many

points. Botany is a new subject to me. With respect to the protrusion

of pollen-tubes, you might like to hear (if you do not already know the

fact) that, as I saw this summer, in the little imperfect flowers of

Viola and Oxalis, which never open, the pollen-tubes always come out of

the pollen-grain, whilst still in the anthers, and direct themselves in

a beautiful manner to the stigma seated at some little distance. I hope

that you will continue your very interesting observations.

LETTER 634. TO J. SCOTT. Down, November 19th [1862].

I am much obliged for your letter, which is full of interesting matter.

I shall be very glad to look at the capsule of the Acropera when

ripe, and pray present my thanks to Mr. MacNab. (634/1. See Letter 608

(Lindley, December 15th, 1861). Also "Fertilisation of Orchids," Edition

II., page 172, for an account of the observations on Acropera which were

corrected by Scott.) I should like to keep it till I could get a capsule

of some other member of the Vandeae for comparison, but ultimately all

the seeds shall be returned, in case you would like to write any

notice on the subject. It was, as I said (634/2. Letter 633.), only

"in desperation" that I suggested that the flower might be a male and

occasionally capable of producing a few seeds. I had forgotten Gartner's

remark; in fact, I know only odds and ends of Botany, and you know far

more. One point makes the above view more probable in Acropera than in

other cases, viz. the presence of rudimentary placentae or testae, for

I cannot hear that these have been observed in the male plants. They do

not occur in male Lychnis dioica, but next spring I will look to male

holly flowers. I fully admit the difficulty of similarity of stigmatic

chamber in the two Acroperas. As far as I remember, the blunt end of

pollen-mass would not easily even stick in the orifice of the chamber.

Your view may be correct about abundance of viscid matter, but seems

rather improbable. Your facts about female flowers occurring where males

alone ought to occur is new to me; if I do not hear that you object, I

will quote the Zea case on your authority in what I am now writing on

the varieties of the maize. (634/3. See "Animals and Plants," Edition

II., Volume I., page 339: "Mr. Scott has lately observed the rarer case

of female flowers on a true male panicle, and likewise hermaphrodite

flowers." Scott's paper on the subject is in "Trans. Bot. Soc.

Edinburgh," Volume VIII. See Letter 151, Volume I.) I am glad to hear

that you are now working on the most curious subject of parthenogenesis.

I formerly fancied that I observed female Lychnis dioica seeded without

pollen. I send by this post a paper on Primula, which may interest you.

(634/4. "Linn. Soc. Journal," 1862.) I am working on the subject, and if

you should ever observe any analogous case I should be glad to hear. I

have added another very clever pamphlet by Prof. Asa Gray. Have you a

copy of my Orchis book? If you have not, and would like one, I should be

pleased to send one. I plainly see that you have the true spirit of an

experimentalist and good observer. Therefore, I ask whether you have

ever made any trials on relative fertility of varieties of plants (like

those I quote from Gartner on the varieties of Verbascum). I much

want information on this head, and on those marvellous cases (as some

Lobelias and Crinum passiflora) in which a plant can be more easily

fertilised by the pollen of another species than by its own good pollen.

I am compelled to write in haste. With many thanks for your kindness.

LETTER 635. TO J. SCOTT. Down, 20th [1862?].

What a magnificent capsule, and good Heavens, what a number of seeds!

I never before opened pods of larger orchids. It did not signify a

few seed being lost, as it would be hopeless to estimate number in

comparison with other species. If you sow any, had you not better sow

a good many? so I enclose small packet. I have looked at the seeds; I

never saw in the British orchids nearly so many empty testae; but

this goes for nothing, as unnatural conditions would account for it. I

suspect, however, from the variable size and transparency, that a

good many of the seeds when dry (and I have put the capsule on my

chimney-piece) will shrivel up. So I will wait a month or two till I get

the capsule of some large Vandeae for comparison. It is more likely that

I have made some dreadful blunder about Acropera than that it should be

male yet not a perfect male. May there be some sexual relation between

A. Loddigesii and luteola; they seem very close? I should very much like

to examine the capsule of the unimpregnated flower of A. Loddigesii.

I have got both species from Kew, but whether we shall have skill to

flower them I know not. One conjectures that it is imperfect male; I

still should incline to think it would produce by seed both sexes.

But you are right about Primula (and a very acute thought it was):

the long-styled P. sinensis, homomorphically fertilised with own-form

pollen, has produced during two successive homomorphic generations only

long-styled plants. (635/1. In "Forms of Flowers," Edition II., page

216, a summary of the transmission of forms in the "homomorphic" unions

of P. sinensis is given. Darwin afterwards used "illegitimate" for

homomorphic, and "legitimate" for "heteromorphic" ("Forms of Flowers,"

Edition i., page 24).) The short-styled the same, i.e. produced

short-styled for two generations with the exception of a single plant.

I cannot say about cowslips yet. I should like to hear your case of the

Primula: is it certainly propagated by seed?

LETTER 636. TO J. SCOTT. Down, December 3rd, [1862?].

What a capital observer you are! and how well you have worked the

primulas. All your facts are new to me. It is likely that I overrate the

interest of the subject; but it seems to me that you ought to publish a

paper on the subject. It would, however, greatly add to the value if you

were to cover up any of the forms having pistil and anther of the same

height, and prove that they were fully self-fertile. The occurrence of

dimorphic and non-dimorphic species in the same genus is quite the

same as I find in Linum. (636/1. Darwin finished his paper on Linum

in December 1862, and it was published in the "Linn. Soc. Journal" in

1863.) Have any of the forms of Primula, which are non-dimorphic, been

propagated for some little time by seed in garden? I suppose not. I

ask because I find in P. sinensis a third rather fluctuating form,

apparently due to culture, with stigma and anthers of same height.

I have been working successive generations homomorphically of this

Primula, and think I am getting curious results; I shall probably

publish next autumn; and if you do not (but I hope you will) publish

yourself previously, I should be glad to quote in abstract some of your

facts. But I repeat that I hope you will yourself publish. Hottonia is

dimorphic, with pollen of very different sizes in the two forms. I think

you are mistaken about Siphocampylus, but I feel rather doubtful in

saying this to so good an observer. In Lobelia the closed pistil grows

rapidly, and pushes out the pollen and then the stigma expands, and the

flower in function is monoecious; from appearance I believe this is the

case with your plant. I hope it is so, for this plant can hardly require

a cross, being in function monoecious; so that dimorphism in such a case

would be a heavy blow to understanding its nature or good in all other

cases. I see few periodicals: when have you published on Clivia? I

suppose that you did not actually count the seeds in the hybrids in

comparison with those of the parent-forms; but this is almost necessary

after Gartner's observations. I very much hope you will make a good

series of comparative trials on the same plant of Tacsonia. (636/2. See

Scott in "Linn. Soc. Journal," VIII.) I have raised 700-800 seedlings

from cowslips, artificially fertilised with care; and they presented not

a hair's-breadth approach to oxlips. I have now seed in pots of cowslip

fertilised by pollen of primrose, and I hope they will grow; I have also

got fine seedlings from seed of wild oxlips; so I hope to make out the

case. You speak of difficulties on Natural Selection: there are indeed

plenty; if ever you have spare time (which is not likely, as I am sure

you must be a hard worker) I should be very glad to hear difficulties

from one who has observed so much as you have. The majority of

criticisms on the "Origin" are, in my opinion, not worth the paper they

are printed on. Sir C. Lyell is coming out with what, I expect, will

prove really good remarks. (636/3. Lyell's "Antiquity of Man" was

published in the spring of 1863. In the "Life and Letters," Volume III.,

pages 8, 11, Darwin's correspondence shows his deep disappointment at

what he thought Lyell's half-heartedness in regard to evolution. See

Letter 164, Volume I.) Pray do not think me intrusive; but if you

would like to have any book I have published, such as my "Journal of

Researches" or the "Origin," I should esteem it a compliment to be

allowed to send it. Will you permit me to suggest one experiment, which

I should much like to see tried, and which I now wish the more from

an extraordinary observation by Asa Gray on Gymnadenia tridentata (in

number just out of Silliman's N. American Journal) (636/4. In Gymnadenia

tridentata, according to Asa Gray, the anther opens in the bud, and the

pollen being somewhat coherent falls on the stigma and on the rostellum

which latter is penetrated by the pollen-tubes. "Fertilisation of

Orchids," Edition II., page 68. Asa Gray's papers are in "American

Journal of Science," Volume XXXIV., 1862, and XXXVI., 1863.); namely,

to split the labellum of a Cattleya, or of some allied orchis, remove

caudicle from pollen-mass (so that no loose grains are about) and put it

carefully into the large tongue-like rostellum, and see if pollen-tubes

will penetrate, or better, see if capsule will swell. Similar

pollen-masses ought to be put on true stigmas of two or three other

flowers of same plants for comparison. It is to discover whether

rostellum yet retains some of its primordial function of being

penetrated by pollen-tubes. You will be sorry that you ever entered

into correspondence with me. But do not answer till at leisure, and as

briefly as you like. My handwriting, I know, is dreadfully bad. Excuse

this scribbling paper, as I can write faster on it, and I have a rather

large correspondence to keep up.

LETTER 637. TO J. SCOTT. Down, January 21st, 1863.

I thank you for your very interesting letter; I must answer as briefly

as I can, for I have a heap of other letters to answer. I strongly

advise you to follow up and publish your observations on the

pollen-tubes of orchids; they promise to be very interesting. If you

could prove what I only conjectured (from state of utriculi in rostellum

and in stigma of Catasetum and Acropera) that the utriculi somehow

induce, or are correlated with, penetration of pollen-tubes you will

make an important physiological discovery. I will mention, as worth

your attention (and what I have anxiously wished to observe, if time had

permitted, and still hope to do)--viz., the state of tissues or cells

of stigma in an utterly sterile hybrid, in comparison with the same

in fertile parent species; to test these cells, immerse stigmas for

48 hours in spirits of wine. I should expect in hybrids that the cells

would not show coagulated contents. It would be an interesting discovery

to show difference in female organs of hybrids and pure species. Anyhow,

it is worth trial, and I recommend you to make it, and publish if

you do. The pollen-tubes directing themselves to stigma is also very

curious, though not quite so new, but well worth investigation when

you get Cattleya, etc., in flower. I say not so new, for remember small

flowers of Viola and Oxalis; or better, see Bibliography in "Natural

History Review," No. VIII., page 419 (October, 1862) for quotation

from M. Baillon on pollen-tubes finding way from anthers to stigma in

Helianthemum. I should doubt gum getting solid from [i.e. because of]

continued secretion. Why not sprinkle fresh plaster of Paris and make

impenetrable crust? (637/1. The suggestion that the stigma should be

covered with a crust of plaster of Paris, pierced by a hole to allow the

pollen-tubes to enter, bears a resemblance to Miyoshi's experiments with

germinating pollen and fungal spores. See "Pringsheim's Jahrbucher,"

1895; "Flora," 1894.) You might modify experiment by making little hole

in one lower corner, and see if tubes find it out. See in my future

paper on Linum pollen and stigma recognising each other. If you will

tell me that pollen smells the stigma I will try and believe you; but

I will not believe the Frenchman (I forget who) who says that stigma of

Vanilla actually attracts mechanically, by some unknown force, the solid

pollen-masses to it! Read Asa Gray in 2nd Review of my Orchis book on

pollen of Gymnadenia penetrating rostellum. I can, if you like, lend

you these Reviews; but they must be returned. R. Brown, I remember, says

pollen-tubes separate from grains before the lower ends of tubes reach

ovules. I saw, and was interested by, abstract of your Drosera paper

(637/2. A short note on the irritability of Drosera in the "Trans. Bot.

Soc. Edin." Volume VII.); we have been at very much the same work.

LETTER 638. TO J. SCOTT. Down, February 16th [1863].

Absence from home has prevented me from answering you sooner. I should

think that the capsule of Acropera had better be left till it shows some

signs of opening, as our object is to judge whether the seeds are good;

but I should prefer trusting to your better judgment. I am interested

about the Gongora, which I hope hereafter to try myself, as I have just

built a small hot-house.

Asa Gray's observations on the rostellum of Gymnadenia are very

imperfect, yet worth looking at. Your case of Imatophyllum is most

interesting (638/1. A sucker of Imatophyllum minatum threw up a shoot

in which the leaves were "two-ranked instead of four-ranked," and showed

other differences from the normal.--"Animals and Plants," Edition II.,

Volume I., page 411.); even if the sport does not flower it will be

worth my giving. I did not understand, or I had forgotten, that a single

frond on a fern will vary; I now see that the case does come under

bud-variation, and must be given by me. I had thought of it only

as proof [of] inheritance in cryptogams; I am much obliged for your

correction, and will consult again your paper and Mr. Bridgeman's.

(638/2. The facts are given in "Animals and Plants," Edition II., Volume

I., page 408.) I enclose varieties of maize from Asa Gray. Pray do not

thank me for trusting you; the thanks ought to go the other way. I

felt a conviction after your first letter that you were a real lover of

Natural History.

If you can advance good evidence showing that bisexual plants are more

variable than unisexual, it will be interesting. I shall be very glad to

read the discussion which you are preparing. I admit as fully as any

one can do that cross-impregnation is the great check to endless

variability; but I am not sure that I understand your view. I do not

believe that the structure of Primula has any necessary relation to

a tendency to a dioecious structure, but seeing the difference in the

fertility of the two forms, I felt bound unwillingly to admit that they

might be a step towards dioeciousness; I allude to this subject in

my Linum paper. (638/3. "Linn. Soc. Journal," 1863.) Thanks for your

answers to my other queries. I forgot to say that I was at Kew the other

day, and I find that they can give me capsules of several Vandeae.

LETTER 639. TO J. SCOTT. Down, March 24th [1863].

Your letter, as every one you have written, has greatly interested me.

If you can show that certain individual Passifloras, under certain known

or unknown conditions of life, have stigmas capable of fertilisation

by pollen from another species, or from another individual of its own

species, yet not by its own individual pollen (its own individual pollen

being proved to be good by its action on some other species), you will

add a case of great interest to me; and which in my opinion would be

quite worth your publication. (639/1. Cases nearly similar to those

observed by Scott were recorded by Gartner and Kolreuter, but in these

instances only certain individuals were self-impotent. In "Animals and

Plants," Edition II., Volume II., page 114, where the phenomenon is

fully discussed, Scott's observations ("Trans. Bot. Soc. Edin." 1863)

are given as the earliest, except for one case recorded by Lecoq

("Fecondation," 1862). Interesting work was afterwards done by

Hildebrand and Fritz Muller, as illustrated in many of the letters

addressed to the latter.) I always imagined that such recorded cases

must be due to unnatural conditions of life; and think I said so in the

"Origin." (639/2. See "Origin of Species," Edition I., page 251, for

Herbert's observations on self-impotence in Hippeastrum. In spite of

the uniformness of the results obtained in many successive years, Darwin

inferred that the plants must have been in an "unnatural state.") I am

not sure that I understand your result, [nor] whether it means what I

have above obscurely expressed. If you can prove the above, do publish;

but if you will not publish I earnestly beg you to let me have the facts

in detail; but you ought to publish, for I may not use the facts for

years. I have been much interested by what you say on the rostellum

exciting pollen to protrude tubes; but are you sure that the rostellum

does excite them? Would not tubes protrude if placed on parts of column

or base of petals, etc., near to the stigma? Please look at the

"Cottage Gardener" (or "Journal of Horticulture") (639/3. "Journal of

Horticulture" and "Cottage Gardener," March 31st, 1863. A short note

describing Cruger's discovery of self-fertilisation in Cattleya,

Epidendrum, etc., and referring to the work of "an excellent observer,

Mr. J. Scott." Darwin adds that he is convinced that he has underrated

the power of tropical orchids occasionally to produce seeds without the

aid of insects.) to be published to-morrow week for letter of mine, in

which I venture to quote you, and in which you will see a curious fact

about unopened orchid flowers setting seed in West Indies. Dr. Cruger

attributes protrusion of tubes to ants carrying stigmatic secretion to

pollen (639/4. In Cruger's paper ("Linn. Soc. Journ." VIII., 1865; read

March 3rd 1864) he speaks of the pollen-masses in situ being acted on by

the stigmatic secretion, but no mention is made of the agency of ants.

He describes the pollen-tubes descending "from the [pollen] masses still

in situ down into the ovarian canal."); but this is mere hypothesis.

Remember, pollen-tubes protrude within anther in Neottia nidus-avis. I

did think it possible or probable that perfect fertilisation might have

been effected through rostellum. What a curious case your Gongora must

be: could you spare me one of the largest capsules? I want to estimate

the number of seed, and try my hand if I can make them grow. This,

however, is a foolish attempt, for Dr. Hooker, who was here a day or two

ago, says they cannot at Calcutta, and yet imported species have seeded

and have naturally spread on to the adjoining trees! Dr. Cruger thinks I

am wrong about Catasetum: but I cannot understand his letter. He admits

there are three forms in two species; and he speaks as if the sexes

were separate in some and that others were hermaphrodites (639/5.

Cruger ("Linn. Soc. Journal," VIII., page 127) says that the apparently

hermaphrodite form is always sterile in Trinidad. Darwin modified

his account in the second edition of the orchid book.); but I cannot

understand what he means. He has seen lots of great humble-bees buzzing

about the flowers with the pollinia sticking to their backs! Happy man!!

I have the promise, but not yet surety, of some curious results with

my homomorphic seedling cowslips: these have not followed the rule of

Chinese Primula; homomorphic seedlings from short-styled parent have

presented both forms, which disgusts me.

You will see that I am better; but still I greatly fear that I must have

a compulsory holiday. With sincere thanks and hearty admiration at your

powers of observation...

My poor P. scotica looks very sick which you so kindly sent me. (639/6.

Sent by Scott, January 6th, 1863.)

LETTER 640. TO J. SCOTT. April 12th [1863].

I really hardly know how to thank you enough for your very interesting

letter. I shall certainly use all the facts which you have given me (in

a condensed form) on the sterility of orchids in the work which I am now

slowly preparing for publication. But why do you not publish these facts

in a separate little paper? (640/1. See Letter 642, note, for reference

to Scott's paper.) They seem to me well worth it, and you really ought

to get your name known. I could equally well use them in my book. I

earnestly hope that you will experiment on Passiflora, and let me give

your results. Dr. A. Gray's observations were made loosely; he said in

a letter he would attend this summer further to the case, which clearly

surprised him much. I will say nothing about the rostellum, stigmatic

utriculi, fertility of Acropera and Catasetum, for I am completely

bewildered: it will rest with you to settle these points by your

excellent observations and experiments. I must own I never could help

doubting Dr. Hooker's case of the poppy. You may like to hear what I

have seen this morning: I found (640/2. See Letter 658.) a primrose

plant with flowers having three pistils, which when pulled asunder,

without any tearing, allowed pollen to be placed on ovules. This I did

with three flowers--pollen-tubes did not protrude after several days.

But this day, the sixteenth (N.B.--primulas seem naturally slowly

fertilised), I found many tubes protruded, and, what is very odd, they

certainly seemed to have penetrated the coats of the ovules, but in

no one instance the foramen of the ovule!! I mention this because

it directly bears on your explanation of Dr. Cruger's case. (640/3.

Cruger's case here referred to is doubtless the cleistogamic

fertilisation of Epidendrum, etc. Scott discusses the question of

self-fertilisation at great length in a letter to Darwin dated April,

and obviously written in 1863. In Epidendrum he observed a viscid matter

extending from the stigmatic chamber to the anther: pollen-tubes had

protruded from the anther not only where it was in contact with the

viscid matter, but also from the central part, and these spread "over

the anterior surface of the rostellum downward into the stigma." Cruger

believed the viscid matter reaching the anther was a necessary condition

for the germination of the pollen-grains. Scott points out that the

viscid matter is produced in large quantity only after the pollen-grains

have penetrated the stigma, and that it is, in fact, a consequence, not

a preliminary to fertilisation. He finally explains Cruger's case thus:

"The greater humidity and equability of temperature consequent on

such conditions [i.e. on the flowers being closed] is, I believe, the

probable cause of these abnormally conditioned flowers so frequently

fertilising themselves." Scott also calls attention to the danger

of being deceived by fungal hyphae in observations on germination of

pollen.) I believe that your explanation is right; I should never have

thought of it; yet this was stupid of me, for I remember thinking that

the almost closed imperfect flowers of Viola and Oxalis were related

to the protrusion of the pollen-tubes. My case of the Aceras with the

aborted labellum squeezed against stigma supports your view. (640/4. See

"Fertilisation of Orchids," Edition II., page 258: the pollen germinated

within the anther of a monstrous flower.) Dr. Cruger's notion about the

ants was a simple conjecture. About cryptogamic filaments, remember Dr.

C. says that the unopened flowers habitually set fruit. I think that you

will change your views on the imperfect flowers of Viola and Oxalis...

LETTER 641. (?)

LETTER 642. TO J. SCOTT. May 2nd [1863].

I have left home for a fortnight to see if I can, with little hope,

improve my health. The parcel of orchid pods, which you have so kindly

sent me, has followed me. I am sure you will forgive the liberty which I

take in returning you the postage stamps. I never heard of such a scheme

as that you were compelled to practise to fertilise the Gongora! (642/1.

See "Fertilisation of Orchids," Edition, II., page 169. "Mr. Scott tried

repeatedly, but in vain, to force the pollen-masses into the stigma of

Gongora atro-purpurea and truncata; but he readily fertilised them by

cutting off the clinandrum and placing pollen-masses on the now exposed

stigma.") It is a most curious problem what plan Nature follows in this

genus and Acropera. (642/2. In the "Fertilisation of Orchids," Edition

II., page 169, Darwin speculates as to the possible fertilisation of

Acropera by an insect with pollen-masses adhering to the extremity of

its abdomen. It would appear that this guess (which does not occur in

the first edition) was made before he heard of Cruger's observation on

the allied genus Gongora, which is visited by a bee with a long tongue,

which projects, when not in use, beyond and above the tip of the

abdomen. Cruger believes that this tongue is the pollinating agent.

Cruger's account is in the "Journal of the Linn. Soc." VIII., 1865,

page 130.) Some day I will try and estimate how many seeds there are in

Gongora. I suppose and hope you have kept notes on all your observations

on orchids, for, with my broken health and many other subjects, I do not

know whether I shall ever have time to publish again; though I have a

large collection of notes and facts ready. I think you show your wisdom

in not wishing to publish too soon; a young author who publishes every

trifle gets, sometimes unjustly, to be disregarded. I do not pretend

to be much of a judge; but I can conscientiously say that I have never

written one word to you on the merit of your letters that I do not fully

believe in. Please remember that I should very much wish for a copy of

your paper on sterility of individual orchids (642/3. "On the Individual

Sterility and Cross-Impregnation of Certain Species of Oncidium." [Read

June 2nd, 1864.] "Linn. Soc. Journal," VIII., 1865. This paper gives a

full account of the self-sterility of Oncidium in cases where the pollen

was efficient in fertilising other individuals of the same species and

of distinct species. Some of the facts were given in Scott's paper,

"Experiments on the Fertilisation of Orchids in the Royal Botanic Garden

of Edinburgh," published in the "Proc. Bot. Soc. Edinb." 1863. It

is probably to the latter paper that Darwin refers.) and on Drosera.

(642/4. "Trans. Bot. Soc. Edinburgh," Volume VII.) Thanks for [note]

about Campanula perfoliata. I have asked Asa Gray for seeds, to whom

I have mentioned your observations on rostellum, and asked him to

look closer to the case of Gymnadenia. (642/5. See "Fertilisation

of Orchids," Edition II., page 68.) Let me hear about the sporting

Imatophyllum if it flowers. Perhaps I have blundered about Primula; but

certainly not about mere protrusion of pollen-tubes. I have been idly

watching bees of several genera and diptera fertilising O. morio at this

place, and it is a very pretty sight. I have confirmed in several ways

the entire truth of my statement that there is no vestige of nectar in

the spur; but the insects perforate the inner coat. This seems to me a

curious little fact, which none of my reviewers have noticed.

LETTER 643. TO J.D. HOOKER. Down, May 23rd [1863].

You can confer a real service on a good man, John Scott, the writer of

the enclosed letter, by reading it and giving me your opinion. I assure

[you] John Scott is a truly remarkable man. The part struck out is

merely that he is not comfortable under Mr. McNab, and this part must be

considered as private. Now the question is, what think you of the offer?

Is expense of living high at Darjeeling? May I say it is healthy? Will

he find the opportunity for experimental observations, which are a

passion with him? It seems to me rather low pay. Will you advise me for

him? I shall say that as far as experiments in hand at the Botanical

Garden in Edinburgh are concerned, it would be a pity to hesitate to

accept the offer.

J. Scott is head of the propagating department. I know you will not

grudge aiding by your advice a good man. I shall tell him that I have

not the slightest power to aid him in any way for the appointment. I

should think voyage out and home ought to be paid for?

LETTER 644. TO JOHN SCOTT. Down, May 25th, 1863.

Now for a few words on science. I do not think I could be mistaken about

the stigma of Bolbophyllum (644/1. Bolbophyllum is remarkable for the

closure of the stigmatic cavity which comes on after the flower has been

open a little while, instead of after fertilisation, as in other genera.

Darwin connects the fact with the "exposed condition of the whole

flower."--"Fertilisation of Orchids," Edition II., page 137.); I had

the plant alive from Kew, and watched many flowers. That is a most

remarkable observation on foreign pollen emitting tubes, but not causing

orifice to close (644/2. See Scott, "Bot. Soc. Edin." 1863, page 546,

note. He applied pollinia from Cypripedium and Asclepias to flowers of

Tricopilia tortilis; and though the pollen germinated, the stigmatic

chamber remained open, yet it invariably closes eighteen hours after the

application of its own pollen.); it would have been interesting to have

observed how close an alliance of form would have acted on the orifice

of the stigma. It will probably be so many years, if ever, [before] I

work up my observations on Drosera, that I will not trouble you to send

your paper, for I could not now find time to read it. If you have spare

copy of your Orchid paper, please send it, but do not get a copy of the

journal, for I can get one, and you must often want to buy books. Let me

know when it is published. I have been glad to hear about Mercurialis,

but I will not accept your offer of seed on account of time, time, time,

and weak health. For the same reason I must give up Primula mollis.

What a wonderful, indefatigable worker you are! You seem to have made a

famous lot of interesting experiments. D. Beaton once wrote that no

man could cross any species of Primula. You have apparently proved the

contrary with a vengeance. Your numerous experiments seem very well

selected, and you will exhaust the subject. Now when you have completed

your work you should draw up a paper, well worth publishing, and give

a list of all the dimorphic and non-dimorphic forms. I can give you,

on the authority of Prof. Treviranus in "Bot. Zeitung," case of P.

longiflora non-dimorphic. I am surprised at your cowslips in this state.

Is it a common yellow cowslip? I have seen oxlips (which from some

experiments I now look at as certainly natural hybrids) in same state.

If you think the Botanical Society of Edinburgh would not do justice

and publish your paper, send it to me to be communicated to the Linnean

Society. I will delay my paper on successive dimorphic generations in

Primula (644/3. Published in the "Journ. Linn. Soc." X., 1869 [1868].)

till yours appears, so as in no way to interfere with your paper.

Possibly my results may be hardly worth publishing, but I think they

will; the seedlings from two successive homomorphic generations seem

excessively sterile. I will keep this letter till I hear from Dr.

Hooker. I shall be very glad if you try Passiflora. Your experiments on

Primula seem so well chosen that whatever the result is they will be of

value. But always remember that not one naturalist out of a dozen cares

for really philosophical experiments.

LETTER 645. TO J. SCOTT. Down, May 31st [1863].

I am unwell, and must write briefly. I am very much obliged for the

"Courant." (645/1. The Edinburgh "Evening Courant" used to publish

notices of the papers read at the Botanical Society of Edinburgh. The

paper referred to here was Scott's on Oncidium.) The facts will be of

highest use to me. I feel convinced that your paper will have permanent

value. Your case seems excellently and carefully worked out. I agree

that the alteration of title was unfortunate, but, after all, title does

not signify very much. So few have attended to such points that I do

not expect any criticism; but if so, I should think you had much better

reply, but I could if you wished it much. I quite understand about the

cases being individual sterility; so Gartner states it was with him.

Would it be worth while to send a corrected copy of the "Courant" to the

"Gardeners' Chronicle?" (645/2. An account of Scott's work appeared in

the "Gardeners' Chronicle," June 13th, 1863, which is, at least partly,

a reprint of the "Courant," since it contains the awkward sentence

criticised by Darwin and referred to below. The title is "On the

Fertilisation of Orchids," which was no doubt considered unfortunate as

not suggesting the subject of the paper, and as being the same as that

of Darwin's book.) I did not know that you had tried Lobelia fulgens:

can you give me any particulars on the number of plants and kinds used,

etc., that I may quote, as in a few days I shall be writing on this

whole subject? No one will ever convince me that it is not a very

important subject to philosophical naturalists. The Hibiscus seems a

very curious case, and I agree with your remarks. You say that you are

glad of criticisms (by the way avoid "former and latter," the reader is

always forced to go back to look). I think you would have made the

case more striking if you had first showed that the pollen of

Oncidium sphacelatum was good; secondly, that the ovule was capable of

fertilisation; and lastly, shown that the plant was impotent with its

own pollen. "Impotence of organs capable of elimination"--capable here

strictly refers to organs; you mean to impotence. To eliminate impotence

is a curious expression; it is removing a non-existent quality. But

style is a trifle compared with facts, and you are capable of writing

well. I find it a good rule to imagine that I want to explain the case

in as few and simple words as possible to one who knows nothing of the

subject. (645/3. See Letter 151, Volume I.) I am tired. In my opinion

you are an excellent observer.

LETTER 646. TO J. SCOTT. Down, June 6th, 1863.

I fear that you think that I have done more than I have with respect to

Dr. Hooker. I did not feel that I had any right to ask him to remember

you for a colonial appointment: all that I have done is to speak most

highly of your scientific merits. Of course this may hereafter fructify.

I really think you cannot go on better, for educational purposes, than

you are now doing,--observing, thinking, and some reading beat, in my

opinion, all systematic education. Do not despair about your style; your

letters are excellently written, your scientific style is a little

too ambitious. I never study style; all that I do is to try to get

the subject as clear as I can in my own head, and express it in the

commonest language which occurs to me. But I generally have to think a

good deal before the simplest arrangement and words occur to me. Even

with most of our best English writers, writing is slow work; it is a

great evil, but there is no help for it. I am sure you have no cause to

despair. I hope and suppose your sending a paper to the Linnean Society

will not offend your Edinburgh friends; you might truly say that you

sent the paper to me, and that (if it turns out so) I thought it worth

communicating to the Linnean Society. I shall feel great interest in

studying all your facts on Primula, when they are worked out and the

seed counted. Size of capsules is often very deceptive. I am astonished

how you can find time to make so many experiments. If you like to send

me your paper tolerably well written, I would look it over and suggest

any criticisms; but then this would cause you extra copying. Remember,

however, that Lord Brougham habitually wrote everything important three

times over. The cases of the Primulae which lose by variation their

dimorphic characters seem to me very interesting. I find that the

mid-styled (by variation) P. sinensis is more fertile with own pollen,

even, than a heteromorphic union! If you have time it will be very good

to experiment on Linum Lewisii. I wrote formerly to Asa Gray begging for

seed. If you have time, I think experiments on any peloric flowers would

be useful. I shall be sorry (and I am certain it is a mistake on the

part of the Society) if your orchid paper is not printed in extenso.

I am now at work compiling all such cases, and shall give a very full

abstract of all your observations. I hope to add in autumn some from

you on Passiflora. I would suggest to you the advantage, at present,

of being very sparing in introducing theory in your papers (I formerly

erred much in Geology in that way): LET THEORY GUIDE YOUR OBSERVATIONS,

but till your reputation is well established be sparing in publishing

theory. It makes persons doubt your observations. How rarely R. Brown

ever indulged in theory: too seldom perhaps! Do not work too hard,

and do not be discouraged because your work is not appreciated by the

majority.

LETTER 647. TO J. SCOTT. July 2nd [1863?]

Many thanks for capsules. I would give table of the Auricula (647/1.

In Scott's paper ("Linn. Soc. Journ." VIII.) many experiments on the

Auricula are recorded.), especially owing to enclosed extract, which you

can quote. Your facts about varying fertility of the primulas will be

appreciated by but very few botanists; but I feel sure that the day will

come when they will be valued. By no means modify even in the slightest

degree any result. Accuracy is the soul of Natural History. It is hard

to become accurate; he who modifies a hair's breadth will never be

accurate. It is a golden rule, which I try to follow, to put every fact

which is opposed to one's preconceived opinion in the strongest light.

Absolute accuracy is the hardest merit to attain, and the highest merit.

Any deviation is ruin. Sincere thanks for all your laborious trials on

Passiflora. I am very busy, and have got two of my sons ill--I very much

fear with scarlet fever; if so, no more work for me for some days or

weeks. I feel greatly interested about your Primula cases. I think it

much better to count seed than to weigh. I wish I had never weighed;

counting is more accurate, though so troublesome.

LETTER 648. TO J. SCOTT. Down, 25th [1863?]

From what you say I looked again at "Bot. Zeitung." (648/1. "Ueber

Dichogamie," "Bot. Zeit." January 1863.) Treviranus speaks of P.

longiflora as short-styled, but this is evidently a slip of the pen, for

further on, I see, he says the stigma always projects beyond anthers.

Your experiments on coloured primroses will be most valuable if proved

true. (648/2. The reference seems to be to Scott's observation that the

variety rubra of the primrose was sterile when crossed with pollen

from the common primrose. Darwin's caution to Scott was in some

measure justified, for in his experiments on seedlings raised by

self-fertilisation of the Edinburgh plants, he failed to confirm Scott's

result. See "Forms of Flowers," Edition II., page 225. Scott's facts are

in the "Journal Linn. Soc." VIII., page 97 (read February 4th, 1864).) I

will advise to best of my power when I see MS. If evidence is not good

I would recommend you, for your reputation's sake, to try them again. It

is not likely that you will be anticipated, and it is a great thing

to fully establish what in future time will be considered an important

discovery (or rediscovery, for no one has noticed Gartner's facts). I

will procure coloured primroses for next spring, but you may rely I will

not publish before you. Do not work too hard to injure your health. I

made some crosses between primrose and cowslip, and I send the results,

which you may use if you like. But remember that I am not quite

certain that I well castrated the short-styled primrose; I believe any

castration would be superfluous, as I find all [these] plants sterile

when insects are excluded. Be sure and save seed of the crossed

differently coloured primroses or cowslips which produced least seed,

to test the fertility of the quasi-hybrid seedlings. Gartner found the

common primrose and cowslip very difficult to cross, but he knew nothing

on dimorphism. I am sorry about delay [of] your orchid paper; I should

be glad of abstract of your new observations of self-sterility in

orchids, as I should probably use the new facts. There will be an

important paper in September in "Annals and Magazine of Natural

History," on ovules of orchids being formed after application of pollen,

by Dr. F. Hildebrand of Bonn. (648/3. "Ann. Mag. Nat. Hist." XII., 1863,

page 169. The paper was afterwards published in the "Bot. Zeitung,"

1863.)

LETTER 649. TO J. SCOTT. Down, November 7th [1863].

Every day that I could do anything, I have read a few pages of your

paper, and have now finished it, and return it registered. (649/1.

This refers to the MS. of Scott's paper on the Primulaceae, "Linn. Soc.

Journ." VIII. [February 4th, 1864] 1865.) It has interested me deeply,

and is, I am sure, an excellent memoir. It is well arranged, and in most

parts well written. In the proof sheets you can correct a little

with advantage. I have suggested a few alterations in pencil for your

consideration, and have put in here and there a slip of paper. There

will be no occasion to rewrite the paper--only, if you agree with me, to

alter a few pages. When finished, return it to me, and I will with the

highest satisfaction communicate it to the Linnean Society. I should be

proud to be the author of the paper. I shall not have caused much delay,

as the first meeting of the Society was on November 5th. When your

Primula paper is finished, if you are so inclined, I should like to

hear briefly about your Verbascum and Passiflora experiments. I tried

Verbascum, and have got the pods, but do not know when I shall be able

to see to the results. This subject might make another paper for you. I

may add that Acropera luteola was fertilised by me, and had produced two

fine pods. I congratulate you on your excellent paper.

P.S.--In the summary to Primula paper can you conjecture what is the

typical or parental form, i.e. equal, long or short styled?

LETTER 650. TO J.D. HOOKER. Down, [January 24th, 1864].

(650/1. Darwin's interest in Scott's Primula work is shown by the

following extracts from a letter to Hooker of January 24th, 1864,

written, therefore, before the paper was read, and also by the

subsequent correspondence with Hooker and Asa Gray. The first part of

this letter illustrates Darwin's condition during a period of especially

bad health.)

As I do nothing all day I often get fidgety, and I now fancy that

Charlie or some of your family [are] ill. When you have time let me have

a short note to say how you all are. I have had some fearful sickness;

but what a strange mechanism one's body is; yesterday, suddenly, I had

a slight attack of rheumatism in my back, and I instantly became almost

well, and so wonderfully strong that I walked to the hot-houses, which

must be more than a hundred yards. I have sent Scott's paper to the

Linnean Society; I feel sure it is really valuable, but I fear few

will care about it. Remember my URGENT wish to be able to send the poor

fellow a word of praise from any one. I have had work to get him to

allow me to send the paper to the Linnean Society, even after it was

written out.

LETTER 651. TO J. SCOTT. Down, February 9th, 1864.

(651/1. Scott's paper on Primulaceae was read at the Linnean Society on

February 4th, 1864.)

The President, Mr. Bentham, I presume, was so much struck by your paper

that he sent me a message to know whether you would like to be elected

an associate. As only one is elected annually, this is a decided honour.

The enclosed list shows what respectable men are associates. I

enclose the rules of admission. I feel sure that the rule that if no

communication is received within three years the associate is considered

to have voluntarily withdrawn, is by no means rigorously adhered to.

Therefore, I advise you to accept; but of course the choice is quite

free. You will see there is no payment. You had better write to me on

this subject, as Dr. Hooker or I will propose you.

LETTER 652. TO J.D. HOOKER. September 13th, 1864.

I have been greatly interested by Scott's paper. I probably overrate

it from caring for the subject, but it certainly seems to me one of the

very most remarkable memoirs on such subjects which I have ever read.

From the subject being complex, and the style in parts obscure, I

suppose very few will read it. I think it ought to be noticed in the

"Natural History Review," otherwise the more remarkable facts will never

be known. Try and persuade Oliver to do it; with the summary it would

not be troublesome. I would offer, but I have sworn to myself I will do

nothing till my volume on "Variation under Domestication" is complete.

I know you will not have time to read Scott, and therefore I will just

point out the new and, as they seem to me, important points.

Firstly, the red cowslip, losing its dimorphic structure and changing

so extraordinarily in its great production of seed with its own pollen,

especially being nearly sterile when fertilised by, or fertilising,

the common cowslip. The analogous facts with red and white primrose.

Secondly, the utter dissimilarity of action of the pollen of long- and

short-styled form of one species in crossing with a distinct species.

And many other points. Will you suggest to Oliver to review this paper?

if he does so, and if it would be of any service to him, I would (as

I have attended so much to these subjects) just indicate, with pages,

leading and new points. I could send him, if he wishes, a separate and

spare copy marked with pencil.

LETTER 653. TO ASA GRAY. September 13th [1864].

(653/1. In September, 1864, Darwin wrote to Asa Gray describing Scott's

work on the Primulaceae as:--)

A paper which has interested me greatly by a gardener, John Scott;

it seems to me a most remarkable production, though written rather

obscurely in parts, but worth the labour of studying. I have just

bethought me that for the chance of your noticing it in the "Journal,"

I will point out the new and very remarkable facts. I have paid the poor

fellow's passage out to India, where I hope he will succeed, as he is a

most laborious and able man, with the manners almost of a gentleman.

(653/2. The following is an abstract of the paper which was enclosed in

the letter to Asa Gray.)

Pages 106-8. Red cowslip by variation has become non-dimorphic, and with

this change of structure has become much more productive of seed than

even the heteromorphic union of the common cowslip. Pages 91-2, similar

case with Auricula; on the other hand a non-dimorphic variety of P.

farinosa (page 115) is less fertile. These changes, or variations,

in the generative system seem to me very remarkable. But far more

remarkable is the fact that the red cowslip (pages 106-8) is very

sterile when fertilising, or fertilised by the common cowslip. Here we

have a new "physiological species." Analogous facts given (page 98) on

the crossing of red and white primroses with common primroses. It is

very curious that the two forms of the same species (pages 93, 94, 95,

and 117) hybridise with extremely different degrees of facility with

distinct species.

He shows (page 94) that sometimes a cross with a quite distinct species

yields more seed than a homomorphic union with own pollen. He shows

(page 111) that of the two homomorphic unions possible with each

dimorphic species the short-styled (as I stated) is the most sterile,

and that my explanation is probably true. There is a good summary to the

paper.

LETTER 654. TO J.D. HOOKER.

(654/1. The following letters to Hooker, April 1st, April 5th and May

22nd, refer to Darwin's scheme of employing Scott as an assistant at

Down, and to Scott's appointment to the Botanic Garden at Calcutta.)

Down, April 1st, 1864.

I shall not at present allude to your very interesting letter (which as

yet has been read to me only twice!), for I am full of a project which I

much want you to consider.

You will have seen Scott's note. He tells me he has no plans for

the future. Thinking over all his letters, I believe he is a truly

remarkable man. He is willing to follow suggestions, but has much

originality in varying his experiments. I believe years may pass before

another man appears fitted to investigate certain difficult and tedious

points--viz. relative fertility of varieties of plants, including

peloric and other monsters (already Scott has done excellent work

on this head); and, secondly, whether a plant's own pollen is less

effective than that of another individual. Now, if Scott is moderate

in his wishes, I would pay him for a year or two to work and publish on

these or other such subjects which might arise. But I dare not have

him here, for it would quite overwork me. There would not be plants

sufficient for his work, and it would probably be an injury to himself,

as it would put him out of the way of getting a good situation. Now, I

believe you have gardeners at Kew who work and learn there without pay.

What do you think of having Scott there for a year or two to work and

experiment? I can see enormous difficulties. In the first place you

will not perhaps think the points indicated so highly important as I do.

Secondly, he would require ground in some out-of-the-way place where the

plants could be covered by a net, which would be unsightly. On the other

hand, I presume you would like a series of memoirs published on work

done at Kew, which I am fully convinced would have permanent value. It

would, of course I conceive, be absolutely necessary that Scott should

be under the regular orders of the superintendent. The only way I can

fancy that it could be done would be to explain to the superintendent

that I temporarily supported Scott solely for the sake of science, and

appeal to his kindness to assist him. If you approved of having

him (which I can see is improbable), and you simply ordered the

superintendent to assist him, I believe everything would go to

loggerheads. As for Scott himself, it would be of course an advantage to

him to study the cultivation at Kew. You would get to know him, and if

he really is a good man you could perhaps be able to recommend him to

some situation at home or abroad. Pray turn this [over] in your mind. I

have no idea whether Scott would like the place, but I can see that

he has a burning zeal for science. He told me that his parents were in

better circumstances, and that he chose a gardener's life solely as the

best way of following science. I may just add that in his last letter he

gives me the results of many experiments on different individuals of the

same species of orchid, showing the most remarkable diversity in their

sexual condition. It seems to me a grievous loss that such a man should

have all his work cut short. Please remember that I know nothing of him

excepting from his letters: these show remarkable talent, astonishing

perseverance, much modesty, and what I admire, determined difference

from me on many points.

What will Sir William say?

LETTER 655. TO J.D. HOOKER. Down, April 5th [1864].

I see my scheme for Scott has invincible difficulties, and I am very

much obliged to you for explaining them at such length. If ever I get

decently well, and Scott is free and willing, I will have him here for

a couple of years to work out several problems, which otherwise would

never be done. I cannot see what will become of the poor fellow. I

enclose a little pamphlet from him, which I suppose is not of much

scientific value, but is surprising as the work of a gardener. If

you have time do just glance over it. I never heard anything so

extraordinary as what you say about poisoning plants, etc.

...The post has just come in. Your interest about Scott is

extraordinarily kind, and I thank you cordially. It seems absurd to

say so, but I suspect that X is prejudiced against Scott because he

partially supports my views. (655/1. In a letter to Scott (dated June

11th) Darwin warns him to keep his views "pretty quiet," and quotes

Hooker's opinion that "if it is known that you agree at all with my

views on species it is enough to make you unpopular in Edinburgh.")

You must not trust my former letter about Clematis. I worked on too

old a plant, and blundered. I have now gone over the work again. It

is really curious that the stiff peduncles are acted upon by a bit of

thread weighing .062 of a grain.

Clematis glandulosa was a valuable present to me. My gardener showed

it to me and said, "This is what they call a Clematis," evidently

disbelieving it. So I put a little twig to the peduncle, and the next

day my gardener said, "You see it is a Clematis, for it feels." That's

the way we make out plants at Down.

My dear old friend, God bless you!

LETTER 656. TO J.D. HOOKER. [May 22nd, 1864].

What a good kind heart you have got. You cannot tell how your letter has

pleased me. I will write to Scott and ask him if he chooses to go out

and risk engagement. If he will not he must want all energy. He says

himself he wants stoicism, and is too sensitive. I hope he may not want

courage. I feel sure he is a remarkable man, with much good in him, but

no doubt many errors and blemishes. I can vouch for his high intellect

(in my judgment he is the best observer I ever came across); for his

modesty, at least in correspondence; and there is something high-minded

in his determination not to receive money from me. I shall ask him

whether he can get a good character for probity and sobriety, and

whether he can get aid from his relations for his voyage out. I will

help, and, if necessary, pay the whole voyage, and give him enough to

support him for some weeks at Calcutta. I will write when I hear from

him. God bless you; you, who are so overworked, are most generous to

take so much trouble about a man you have had nothing to do with.

(656/1. Scott had left the Botanic Gardens at Edinburgh in March 1864,

chagrined at what, justly or unjustly, he considered discouragement and

slight. The Indian offer was most gladly and gratefully accepted.)

LETTER 657. TO J. SCOTT. Down, November 1st, 1871.

Dr. Hooker has forwarded to me your letter as the best and simplest plan

of explaining affairs. I am sincerely grieved to hear of the pecuniary

problem which you have undergone, but now fortunately passed. I assure

you that I have never entertained any feelings in regard to you which

you suppose. Please to remember that I distinctly stated that I did not

consider the sum which I advanced as a loan, but as a gift; and surely

there is nothing discreditable to you, under the circumstances, in

receiving a gift from a rich man, as I am. Therefore I earnestly beg

you to banish the whole subject from your mind, and begin laying up

something for yourself in the future. I really cannot break my word and

accept payment. Pray do not rob me of my small share in the credit of

aiding to put the right man in the right place. You have done good work,

and I am sure will do more; so let us never mention the subject again.

I am, after many interruptions, at work again on my essay on Expression,

which was written out once many months ago. I have found your remarks

the best of all which have been sent me, and so I state.

CHAPTER 2.XI.--BOTANY, 1863-1881.

2.XI.I. Miscellaneous, 1863-1866.--2.XI.II. Correspondence with Fritz

Muller, 1865-1881.--2.XI.III. Miscellaneous, 1868-1881.

2.XI.I. MISCELLANEOUS, 1863-1866.

LETTER 658. TO D. OLIVER. Down [April, 1863].

(658/1. The following letter illustrates the truth of Sir W.

Thiselton-Dyer's remark that Darwin was never "afraid of his facts."

(658/2. "Charles Darwin" (Nature Series), 1882, page 43.) The entrance

of pollen-tubes into the nucellus by the chalaza, instead of through the

micropyle, was first fully demonstrated by Treub in his paper "Sur les

Casuarinees et leur place dans le Systeme naturel," published in the

"Ann. Jard. Bot. Buitenzorg," X., 1891. Two years later Miss Benson gave

an account of a similar phenomenon in certain Amentiferae ("Trans. Linn.

Soc." 1888-94, page 409). This chalazogamic method of fertilisation has

since been recognised in other flowering plants, but not, so far as we

are aware, in the genus Primula.)

It is a shame to trouble [you], but will you tell me whether the ovule

of Primula is "anatropal," nearly as figured by Gray, page 123, "Lessons

in Botany," or rather more tending to "amphitropal"? I never looked at

such a point before. Why I am curious to know is because I put pollen

into the ovarium of monstrous primroses, and now, after sixteen days,

and not before (the length of time agrees with slowness of natural

impregnation), I find abundance of pollen-tubes emitted, which cling

firmly to the ovules, and, I think I may confidently state, penetrate

the ovule. But here is an odd thing: they never once enter at (what I

suppose to be) the "orifice," but generally at the chalaza...Do you

know how pollen-tubes go naturally in Primula? Do they run down walls

of ovarium, and then turn up the placenta, and so debouch near the

"orifices" of the ovules?

If you thought it worth while to examine ovules, I would see if there

are more monstrous flowers, and put pollen into the ovarium, and send

you the flowers in fourteen or fifteen days afterwards. But it is rather

troublesome. I would not do it unless you cared to examine the ovules.

Like a foolish and idle man, I have wasted a whole morning over them...

In two ovules there was an odd appearance, as if the outer coat of ovule

at the chalaza end (if I understand the ovule) had naturally opened or

withered where most of the pollen-tubes seemed to penetrate, which made

me at first think this was a widely open foramen. I wonder whether the

ovules could be thus fertilised?

LETTER 659. TO D. OLIVER. Down [April, 1863].

Many thanks about the Primula. I see that I was pretty right about the

ovules. I have been thinking that the apparent opening at the chalaza

end must have been withering or perhaps gnawing by some very minute

insects, as the ovarium is open at the upper end. If I have time I will

have another look at pollen-tubes, as, from what you say, they ought

to find their way to the micropyle. But ovules to me are far more

troublesome to dissect than animal tissue; they are so soft, and muddy

the water.

LETTER 660. TO MAXWELL MASTERS. Down, April 6th [1863].

I have been very glad to read your paper on Peloria. (660/1. "On the

Existence of Two Forms of Peloria." "Natural History Review," April,

1863, page 258.) For the mere chance of the following case being new

I send it. A plant which I purchased as Corydalis tuberosa has, as you

know, one nectary--short, white, and without nectar; the pistil is bowed

towards the true nectary; and the hood formed by the inner petals slips

off towards the opposite side (all adaptations to insect agency, like

many other pretty ones in this family). Now on my plants there are

several flowers (the fertility of which I will observe) with both

nectaries equal and purple and secreting nectar; the pistil is straight,

and the hood slips off either way. In short, these flowers have the

exact structure of Dielytra and Adlumia. Seeing this, I must look at

the case as one of reversion; though it is one of the spreading of

irregularity to two sides.

As columbine [Aquilegia] has all petals, etc., irregular, and as

monkshood [Aconitum] has two petals irregular, may not the case given by

Seringe, and referred to [by] you (660/2. "Seringe describes and figures

a flower [of Aconitum] wherein all the sepals were helmet-shaped," and

the petals similarly affected. Maxwell Masters, op. cit., page 260.),

by you be looked at as reversion to the columbine state? Would it be

too bold to suppose that some ancient Linaria, or allied form, and

some ancient Viola, had all petals spur-shaped, and that all cases of

"irregular peloria" in these genera are reversions to such imaginary

ancient form? (660/3. "'Regular or Congenital Peloria' would include

those flowers which, contrary to their usual habit, retain throughout

the whole of their growth their primordial regularity of form and

equality of proportion. 'Irregular or Acquired Peloria,' on the other

hand, would include those flowers in which the irregularity of growth

that ordinarily characterises some portions of the corolla is manifested

in all of them." Maxwell Masters, loc. cit.)

It seems to me, in my ignorance, that it would be advantageous to

consider the two forms of Peloria WHEN OCCURRING IN THE VERY SAME

SPECIES as probably due to the same general law--viz., one as reversion

to very early state, and the other as reversion to a later state when

all the petals were irregularly formed. This seems at least to me a

priori a more probable view than to look at one form of Peloria as due

to reversion and the other as something distinct. (660/4. See Maxwell

Masters, "Vegetable Teratology," 1869, page 235; "Variation of Animals

and Plants," Edition II., Volume II., page 33.)

What do you think of this notion?

LETTER 661. TO P.H. GOSSE.

(661/1. The following was written in reply to Mr. Gosse's letter of May

30th asking for a solution of his difficulties in fertilising Stanhopea.

It is reprinted by the kind permission of Mr. Edmund Gosse from his

delightful book, the "Life of Philip Henry Gosse," London, 1890, page

299.)

Down, June 2nd, 1863.

It would give me real pleasure to resolve your doubts, but I cannot.

I can give only suspicions and my grounds for them. I should think the

non-viscidity of the stigmatic hollow was due to the plant not living

under its natural conditions. Please see what I have said on Acropera.

An excellent observer, Mr. J. Scott, of the Botanical Gardens,

Edinburgh, finds all that I say accurate, but, nothing daunted, he with

the knife enlarged the orifice and forced in pollen-masses; or he simply

stuck them into the contracted orifice without coming into contact

with the stigmatic surface, which is hardly at all viscid, when, lo and

behold, pollen-tubes were emitted and fine seed capsules obtained. This

was effected with Acropera Loddigesii; but I have no doubt that I have

blundered badly about A. luteola. I mention all this because, as Mr.

Scott remarks, as the plant is in our hot-houses, it is quite incredible

it ever could be fertilised in its native land. The whole case is an

utter enigma to me. Probably you are aware that there are cases (and

it is one of the oddest facts in Physiology) of plants which, under

culture, have their sexual functions in so strange a condition, that

though their pollen and ovules are in a sound state and can fertilise

and be fertilised by distinct but allied species, they cannot fertilise

themselves. Now, Mr. Scott has found this the case with certain orchids,

which again shows sexual disturbance. He had read a paper at the

Botanical Society of Edinburgh, and I daresay an abstract which I have

seen will appear in the "Gardeners' Chronicle"; but blunders have crept

in in copying, and parts are barely intelligible. How insects act with

your Stanhopea I will not pretend to conjecture. In many cases I believe

the acutest man could not conjecture without seeing the insect at

work. I could name common English plants in this predicament. But the

musk-orchis [Herminium monorchis] is a case in point. Since publishing,

my son and myself have watched the plant and seen the pollinia

removed, and where do you think they invariably adhere in dozens of

specimens?--always to the joint of the femur with the trochanter of the

first pair of legs, and nowhere else. When one sees such adaptation as

this, it would be hopeless to conjecture on the Stanhopea till we know

what insect visits it. I have fully proved that my strong suspicion was

correct that with many of our English orchids no nectar is excreted, but

that insects penetrate the tissues for it. So I expect it must be with

many foreign species. I forgot to say that if you find that you cannot

fertilise any of your exotics, take pollen from some allied form, and it

is quite probable that will succeed. Will you have the kindness to look

occasionally at your bee-Ophrys near Torquay, and see whether pollinia

are ever removed? It is my greatest puzzle. Please read what I have said

on it, and on O. arachnites. I have since proved that the account of the

latter is correct. I wish I could have given you better information.

P.S.--If the Flowers of the Stanhopea are not too old, remove

pollen-masses from their pedicels, and stick them with a little liquid

pure gum to the stigmatic cavity. After the case of the Acropera, no one

can dare positively say that they would not act.

LETTER 662. TO J.D. HOOKER. Down, Saturday, 5th [December 1863].

I am very glad that this will reach you at Kew. You will then get rest,

and I do hope some lull in anxiety and fear. Nothing is so dreadful in

this life as fear; it still sickens me when I cannot help remembering

some of the many illnesses our children have endured. My father, who

was a sceptical man, was convinced that he had distinctly traced several

cases of scarlet fever to handling letters from convalescents.

The vases (662/1. Probably Wedgwood ware.) did come from my sister

Susan. She is recovering, and was much pleased to hear that you liked

them; I have now sent one of your notes to her, in which you speak of

them as "enchanting," etc. I have had a bad spell--vomiting, every

day for eleven days, and some days many times after every meal. It is

astonishing the degree to which I keep up some strength. Dr. Brinton was

here two days ago, and says he sees no reason [why] I may not recover my

former degree of health. I should like to live to do a little more work,

and often I feel sure I shall, and then again I feel that my tether is

run out.

Your Hastings note, my dear old fellow, was a Copley Medal to me and

more than a Copley Medal: not but what I know well that you overrate

what I have been able to do. (662/2. The proposal to give the medal

to Darwin failed in 1863, but his friends were successful in 1864: see

"Life and Letters," III., page 28.) Now that I am disabled, I feel more

than ever what a pleasure observing and making out little difficulties

is. By the way, here is a very little fact which may interest you. A

partridge foot is described in "Proc. Zoolog. Soc." with a huge ball of

earth attached to it as hard as rock. (662/3. "Proc. Zool. Soc." 1863,

page 127, by Prof. Newton, who sent the foot to Darwin: see "Origin,"

Edition VI., page 328.) Bird killed in 1860. Leg has been sent me, and I

find it diseased, and no doubt the exudation caused earth to accumulate;

now already thirty-two plants have come up from this ball of earth.

By Jove! I must write no more. Good-bye, my best of friends.

There is an Italian edition of the "Origin" preparing. This makes the

fifth foreign edition--i.e. in five foreign countries. Owen will not be

right in telling Longmans that the book would be utterly forgotten in

ten years. Hurrah!

LETTER 663. TO D. OLIVER. Down, February 17th [1864].

Many thanks for the Epacrids, which I have kept, as they will interest

me when able to look through the microscope.

Dr. Cruger has sent me the enclosed paper, with power to do what I think

fit with it. He would evidently prefer it to appear in the "Nat. Hist.

Review." Please read it, and let me have your decision pretty soon. Some

germanisms must be corrected; whether woodcuts are necessary I have not

been able to pay attention enough to decide. If you refuse, please send

it to the Linnean Society as communicated by me. (663/1. H. Cruger's

"A Few Notes on the Fecundation of Orchids, etc." [Read March, 1864.]

"Linn. Soc. Journ." VIII., 1864-5, page 127.) The paper has interested

me extremely, and I shall have no peace till I have a good boast. The

sexes are separate in Catasetum, which is a wonderful relief to me, as I

have had two or three letters saying that the male C. tridentatum seeds.

(663/2. See footnote Letter 608 on the sexual relation between the three

forms known as Catasetum tridentatum, Monacanthus viridis, and Myanthus

barbatus. For further details see Darwin, "Linn. Soc. Journ." VI., 1862,

page 151, and "Fertilisation of Orchids," Edition II., page 196.) It

is pretty clear to me that two or three forms are confounded under this

name. Observe how curiously nearly perfect the pollen of the female is,

according to Cruger,--certainly more perfect than the pollen from the

Guyana species described by me. I was right in the manner in which the

pollen adheres to the hairy back of the humble-bee, and hence the

force of the ejection of the pollina. (663/3. This view was given in

"Fertilisation of Orchids," Edition I., 1862, page 230.) I am still more

pleased that I was right about insects gnawing the fleshy labellum.

This is important, as it explains all the astounding projections on the

labellum of Oncidium, Phalaenopsis, etc.

Excuse all my boasting. It is the best medicine for my stomach. Tell me

whether you mean to take up orchids, as Hooker said you were thinking of

doing. Do you know Coryanthes, with its wonderful basket of water? See

what Cruger says about it. It beats everything in orchids. (663/4. For

Coryanthes see "Fertilisation of Orchids," Edition II., page 173.)

LETTER 664. TO J.D. HOOKER. Down [September 13th, 1864].

Thanks for your note of the 5th. You think much and greatly too much

of me and my doings; but this is pleasant, for you have represented for

many years the whole great public to me.

I have read with interest Bentham's address on hybridism. I am glad

that he is cautious about Naudin's view, for I cannot think that it will

hold. (664/1. C. Naudin's "Nouvelles Recherches sur l'Hydridite dans les

Vegetaux." The complete paper, with coloured plates, was presented to

the Academy in 1861, and published in full in the "Nouvelles Archives

de Museum d'Hist. Nat." Volume I., 1865, page 25. The second part only

appeared in the "Ann. Sci. Nat." XIX., 1863. Mr. Bentham's address

dealing with hybridism is in "Proc. Linn. Soc." VIII., 1864, page ix.

A review of Naudin is given in the "Natural History Review," 1864,

page 50. Naudin's paper is of much interest, as containing a mechanical

theory of reproduction of the same general character as that of

pangenesis. In the "Variation of Animals and Plants," Edition II.,

Volume II., page 395, Darwin states that in his treatment of hybridism

in terms of gemmules he is practically following Naudin's treatment of

the same theme in terms of "essences." Naudin, however, does not clearly

distinguish between hybrid and pure gemmules, and makes the assumption

that the hybrid or mixed essences tend constantly to dissociate into

pure parental essences, and thus lead to reversion. It is to this view

that Darwin refers when he says that Naudin's view throws no light on

the reversion to long-lost characters. His own attempt at explaining

this fact occurs in "Variation under Domestication," II., Edition II.,

page 395. Mr. Bateson ("Mendel's Principle of Heredity," Cambridge,

1902, page 38) says: "Naudin clearly enuntiated what we shall henceforth

know as the Mendelian conception of the dissociation of characters of

cross-breds in the formation of the germ-cells, though apparently he

never developed this conception." It is remarkable that, as far as we

know, Darwin never in any way came across Mendel's work. One of Darwin's

correspondents, however, the late Mr. T. Laxton, of Stamford, was close

on the trail of Mendelian principle. Mr. Bateson writes (op. cit., page

181): "Had he [Laxton] with his other gifts combined this penetration

which detects a great principle hidden in the thin mist of 'exceptions,'

we should have been able to claim for him that honour which must ever

be Mendel's in the history of discovery.") The tendency of hybrids

to revert to either parent is part of a wider law (which I am fully

convinced that I can show experimentally), namely, that crossing races

as well as species tends to bring back characters which existed in

progenitors hundreds and thousands of generations ago. Why this should

be so, God knows. But Naudin's view throws no light, that I can see,

on this reversion of long-lost characters. I wish the Ray Society would

translate Gartner's "Bastarderzeugung"; it contains more valuable matter

than all other writers put together, and would do great service

if better known. (664/2. "Versuche uber die Bastarderzeugung im

Pflanzenreich": Stuttgart, 1849.)

LETTER 665. TO T.H. HUXLEY.

(665/1. Mr. Huxley had doubted the accuracy of observations on Catasetum

published in the "Fertilisation of Orchids." In what formed the

postscript to the following letter, Darwin wrote: "I have had more

Catasetums,--all right, you audacious 'caviller.'")

Down, October 31st [1862].

In a little book, just published, called the "Three Barriers" (a

theological hash of old abuse of me), Owen gives to the author a new

resume of his brain doctrine; and I thought you would like to hear of

this. He ends with a delightful sentence. "No science affords more scope

or easier ground for the caviller and controversialist; and these do

good by preventing scholars from giving more force to generalisations

than the master propounding them does, or meant his readers or hearers

to give."

You will blush with pleasure to hear that you are of some use to the

master.

LETTER 666. TO J.D. HOOKER. [February, 1864?]

I shall write again. I write now merely to ask, if you have Naravelia

(666/1. Ranunculaceae.) (the Clematis-like plant told me by Oliver),

to try and propagate me a plant at once. Have you Clematis cirrhosa? It

will amuse me to tell you why Clematis interests me, and why I should

so very much like to have Naravelia. The leaves of Clematis have no

spontaneous movement, nor have the internodes; but when by growth the

peduncles of leaves are brought into contact with any object, they bend

and catch hold. The slightest stimulus suffices, even a bit of cotton

thread a few inches long; but the stimulus must be applied during six

or twelve hours, and when the peduncles once bend, though the touching

object be removed, they never get straight again. Now mark the

difference in another leaf-climber--viz., Tropaeolum: here the young

internodes revolve day and night, and the peduncles of the leaves are

thus brought into contact with an object, and the slightest momentary

touch causes them to bend in any direction and catch the object, but as

the axis revolves they must be often dragged away without catching, and

then the peduncles straighten themselves again, and are again ready to

catch. So that the nervous system of Clematis feels only a prolonged

touch--that of Tropaeolum a momentary touch: the peduncles of the latter

recover their original position, but Clematis, as it comes into contact

by growth with fixed objects, has no occasion to recover its position,

and cannot do so. You did send me Flagellaria, but most unfortunately

young plants do not have tendrils, and I fear my plant will not get them

for another year, and this I much regret, as these leaf-tendrils seem

very curious, and in Gloriosa I could not make out the action, but

I have now a young plant of Gloriosa growing up (as yet with simple

leaves) which I hope to make out. Thank Oliver for decisive answer about

tendrils of vines. It is very strange that tendrils formed of modified

leaves and branches should agree in all their four highly remarkable

properties. I can show a beautiful gradation by which LEAVES produce

tendrils, but how the axis passes into a tendril utterly puzzles me. I

would give a guinea if vine-tednrils could be found to be leaves.

(666/2. It is an interesting fact that Darwin's work on climbing plants

was well advanced before he discovered the existence of the works of

Palm, Mohl, and Dutrochet on this subject. On March 22nd, 1864, he

wrote to Hooker:--"You quite overrate my tendril work, and there is no

occasion to plague myself about priority." In June he speaks of having

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.")

LETTER 667. TO J.D. HOOKER. Down, June 2nd [1864].

You once offered me a Combretum. (667/1. The two forms of shoot in C.

argenteum are described in "Climbing Plants," page 41.) I having C.

purpureum, out of modesty like an ass refused. Can you now send me

a plant? I have a sudden access of furor about climbers. Do you grow

Adlumia cirrhosa? Your seed did not germinate with me. Could you have

a seedling dug up and potted? I want it fearfully, for it is a

leaf-climber, and therefore sacred.

I have some hopes of getting Adlumia, for I used to grow the plant,

and seedlings have often come up, and we are now potting all minute

reddish-coloured weeds. (667/2. We believe that the Adlumia which came

up year by year in flower boxes in the Down verandah grew from seed

supplied by Asa Gray.) I have just got a plant with sensitive axis,

quite a new case; and tell Oliver I now do not care at all how many

tendrils he makes axial, which at one time was a cruel torture to me.

LETTER 668. TO J.D. HOOKER. Down, November 3rd [1864].

Many thanks for your splendid long letter. But first for business.

Please look carefully at the enclosed specimen of Dicentra

thalictriformis, and throw away. (668/1. Dicentra thalictrifolia, a

Himalayan species of Fumariaceae, with leaf-tendrils.) When the plant

was young I concluded certainly that the tendrils were axial, or

modified branches, which Mohl says is the case with some Fumariaceae.

(668/2. "Ueber den Bau und das Winden der Ranken und Schlingpflanzen.

Eine gekronte Preisschrift," 4to, Tubingen, 1827. At page 43 Mohl

describes the tips of the branches of Fumaria [Corydalis] clavicualta

as being developed into tendrils, as well as the leaves. For this reason

Darwin placed the plant among the tendril-bearers rather than among the

true leaf-climbers: see "Climbing Plants," Edition II., 1875, page 121.)

You looked at them here and agreed. But now the plant is old, what I

thought was a branch with two leaves and ending in a tendril looks

like a gigantic leaf with two compound leaflets, and the terminal part

converted into a tendril. For I see buds in the fork between supposed

branch and main stem. Pray look carefully--you know I am profoundly

ignorant--and save me from a horrid mistake.

LETTER 669. TO J.D. HOOKER.

(669/1. The following is interesting, as containing a foreshadowing of

the chemotaxis of antherozoids which was shown to exist by Pfeffer in

1881: see "Untersuchungen aus dem botanischen Institut zu Tubingen,"

Volume I., page 363. There are several papers by H.J. Carter on the

reproduction of the lower organisms in the "Annals and Magazine of

Natural History" between 1855 and 1865.)

Down, Sunday, 22nd, and Saturday, 28th [October, 1865].

I have been wading through the "Annals and Mag. of N. History." for last

ten years, and have been interested by several papers, chiefly, however,

translations; but none have interested me more than Carter's on lower

vegetables, infusoria, and protozoa. Is he as good a workman as he

appears? for if so he would deserve a Royal medal. I know it is not new;

but how wonderful his account of the spermatozoa of some dioecious alga

or conferva, swimming and finding the minute micropyle in a distinct

plant, and forcing its way in! Why, these zoospores must possess some

sort of organ of sense to guide their locomotive powers to the small

micropyle; and does not this necessarily imply something like a nervous

system, in the same way as complemental male cirripedes have organs of

sense and locomotion, and nothing else but a sack of spermatozoa?

LETTER 670. TO F. HILDEBRAND. May 16th, 1866.

Since writing to you before, I have read your admirable memoir on

Salvia (670/1. "Pringsheim's Jahrbucher," Volume IV., 1866.), and it has

interested me almost as much as when I first investigated the structure

of orchids. Your paper illustrates several points in my "Origin of

Species," especially the transition of organs. Knowing only two or three

species in the genus, I had often marvelled how one cell of the anther

could have been transformed into the moveable plate or spoon; and how

well you show the gradations. But I am surprised that you did not more

strongly insist on this point.

I shall be still more surprised if you do not ultimately come to the

same belief with me, as shown by so many beautiful contrivances,--that

all plants require, from some unknown cause, to be occasionally

fertilised by pollen from a distinct individual.

(PLATE: FRITZ MULLER.)

2.XI.II. CORRESPONDENCE WITH FRITZ MULLER, 1865-1881.

(671/1. The letters from Darwin to Muller are given as a separate group,

instead of in chronological sequence with the other botanical letters,

as better illustrating the uninterrupted friendship and scientific

comradeship of the two naturalists.)

LETTER 671. TO F. MULLER. Down, October 17th [1865].

I received about a fortnight ago your second letter on climbing plants,

dated August 31st. It has greatly interested me, and it corrects and

fills up a great hiatus in my paper. As I thought you could not object,

I am having your letter copied, and will send the paper to the Linnean

Society. (671/2. "Notes on some of the Climbing Plants near Desterro"

[1865], "Linn. Soc. Journ." IX., 1867.) I have slightly modified the

arrangement of some parts and altered only a few words, as you write as

good English as an Englishman. I do not quite understand your account of

the arrangement of the leaves of Strychnos, and I think you use the word

"bracteae" differently to what English authors do; therefore I will get

Dr. Hooker to look over your paper.

I cannot, of course, say whether the Linnean Society will publish your

paper; but I am sure it ought to do so. As the Society is rather poor,

I fear that it will give only a few woodcuts from your truly admirable

sketches.

LETTER 672. TO F. MULLER.

(672/1. In Darwin's book on Climbing Plants, 1875 (672/2. First given

as a paper before the Linnean Society, and published in the "Linn. Soc.

Journ." Volume IX.,), he wrote (page 205): "The conclusion is forced on

our minds that the capacity of revolving, on which most climbing plants

depend, is inherent, though undeveloped, in almost every plant in the

vegetable Kingdom"--a conclusion which was verified in the "Power of

Movement in Plants." The present letter is interesting in referring

to Fritz Muller's observations on the "revolving nutation," or

circumnutation of Alisma macrophylla and Linum usitatissimum, the latter

fact having been discovered by F. Muller's daughter Rosa. This

was probably the earliest observation on the circumnutation of a

non-climbing plant, and Muller, in a paper dated 1868, and published in

Volume V. of the "Jenaische Zeitschrift," page 133, calls attention to

its importance in relation to the evolution of the habit of climbing.

The present letter was probably written in 1865, since it refers to

Muller's paper read before the Linnean Soc. on December 7th, 1865. If

so, the facts on circumnutation must have been communicated to Darwin

some years before their publication in the "Jenaische Zeitschrift.")

Down, December 9th [1865].

I have received your interesting letter of October 10th, with its new

facts on branch-tendrils. If the Linnean Society publishes your paper

(672/3. Ibid., 1867, page 344.), as I am sure it ought to do, I will

append a note with some of these new facts.

I forwarded immediately your MS. to Professor Max Schultze, but I did

not read it, for German handwriting utterly puzzles me, and I am so

weak, I am capable of no exertion. I took the liberty, however, of

asking him to send me a copy, if separate ones are printed, and I

reminded him about the Sponge paper.

You will have received before this my book on orchids, and I wish I

had known that you would have preferred the English edition. Should the

German edition fail to reach you, I will send an English one. That is a

curious observation of your daughter about the movement of the apex of

the stem of Linum, and would, I think, be worth following out. (672/4.

F. Muller, "Jenaische Zeitschrift," Bd. V., page 137. Here, also, are

described the movements of Alisma.) I suspect many plants move a little,

following the sun; but all do not, for I have watched some pretty

carefully.

I can give you no zoological news, for I live the life of the most

secluded hermit.

I occasionally hear from Ernest Hackel, who seems as determined as you

are to work out the subject of the change of species. You will have seen

his curious paper on certain medusae reproducing themselves by seminal

generation at two periods of growth.

(672/5. On April 3rd, 1868, Darwin wrote to F. Muller: "Your diagram of

the movements of the flower-peduncle of the Alisma is extremely curious.

I suppose the movement is of no service to the plant, but shows how

easily the species might be converted into a climber. Does it bend

through irritability when rubbed?"

LETTER 673. TO F. MULLER. Down, September 25th [1866].

I have just received your letter of August 2nd, and am, as usual,

astonished at the number of interesting points which you observe. It

is quite curious how, by coincidence, you have been observing the same

subjects that have lately interested me.

Your case of the Notylia is quite new to me (673/1. See F. Muller, "Bot.

Zeitung," 1868, page 630; "Fertilisation of Orchids," Edition II., page

171.); but it seems analogous with that of Acropera, about the sexes

of which I blundered greatly in my book. I have got an Acropera now in

flower, and have no doubt that some insect, with a tuft of hairs on its

tail, removes by the tuft, the pollinia, and inserts the little viscid

cap and the long pedicel into the narrow stigmatic cavity, and leaves

it there with the pollen-masses in close contact with, but not inserted

into, the stigmatic cavity. I find I can thus fertilise the flowers, and

so I can with Stanhopea, and I suspect that this is the case with your

Notylia. But I have lately had an orchis in flower--viz. Acineta,

which I could not anyhow fertilise. Dr. Hildebrand lately wrote a paper

(673/2. "Bot. Zeitung," 1863, 1865.) showing that with some orchids

the ovules are not mature and are not fertilised until months after

the pollen-tubes have penetrated the column, and you have independently

observed the same fact, which I never suspected in the case of Acropera.

The column of such orchids must act almost like the spermatheca of

insects. Your orchis with two leaf-like stigmas is new to me; but I

feel guilty at your wasting your valuable time in making such beautiful

drawings for my amusement.

Your observations on those plants being sterile which grow separately,

or flower earlier than others, are very interesting to me: they would be

worth experimenting on with other individuals. I shall give in my next

book several cases of individual plants being sterile with their

own pollen. I have actually got on my list Eschscholtzia (673/3. See

"Animals and Plants," II., Edition II., page 118.) for fertilising with

its own pollen, though I did not suspect it would prove sterile, and

I will try next summer. My object is to compare the rate of growth of

plants raised from seed fertilised by pollen from the same flower and by

pollen from a distinct plant, and I think from what I have seen I shall

arrive at interesting results. Dr. Hildebrand has lately described

a curious case of Corydalis cava which is quite sterile with its own

pollen, but fertile with pollen of any other individual plant of the

species. (673/4. "International Horticultural Congress," London, 1866,

quoted in "Variation of Animals and Plants," Edition II., Volume

II., page 113.) What I meant in my paper on Linum about plants being

dimorphic in function alone, was that they should be divided into two

equal bodies functionally but not structurally different. I have been

much interested by what you say on seeds which adhere to the valves

being rendered conspicuous. You will see in the new edition of the

"Origin" (673/5. "Origin of Species," Edition IV., 1866, page 238. A

discussion on the origin of beauty, including the bright colours of

flowers and fruits.) why I have alluded to the beauty and bright colours

of fruit; after writing this it troubled me that I remembered to have

seen brilliantly coloured seed, and your view occurred to me. There is a

species of peony in which the inside of the pod is crimson and the seeds

dark purple. I had asked a friend to send me some of these seeds, to

see if they were covered with anything which could prove attractive to

birds. I received some seeds the day after receiving your letter, and I

must own that the fleshy covering is so thin that I can hardly believe

it would lead birds to devour them; and so it was in an analogous case

with Passiflora gracilis. How is this in the cases mentioned by you? The

whole case seems to me rather a striking one.

I wish I had heard of Mikania being a leaf-climber before your paper

was printed (673/6. See "Climbing Plants (3rd thousand, 1882), page 116.

Mikania and Mutisia both belong to the Compositae. Mikania scandens is a

twining plant: it is another species which, by its leaf-climbing habit,

supplies a transition to the tendril-climber Mutisia. F. Muller's

paper is in "Linn. Soc. Journ." IX., page 344.), for we thus get a

good gradation from M. scandens to Mutisia, with its little modified,

leaf-like tendrils.

I am glad to hear that you can confirm (but render still more wonderful)

Hackel's most interesting case of Linope. Huxley told me that he thought

the case would somehow be explained away.

LETTER 674. TO F. MULLER. Down [Received January 24th, 1867].

I have so much to thank you for that I hardly know how to begin. I have

received the bulbils of Oxalis, and your most interesting letter of

October 1st. I planted half the bulbs, and will plant the other half

in the spring. The case seems to me very curious, and until trying some

experiments in crossing I can form no conjecture what the abortion of

the stamens in so irregular a manner can signify. But I fear from what

you say the plant will prove sterile, like so many others which increase

largely by buds of various kinds. Since I asked you about Oxalis, Dr.

Hildebrand has published a paper showing that a great number of species

are trimorphic, like Lythrum, but he has tried hardly any experiments.

(674/1. Hildebrand's work, published in the "Monatsb. d. Akad. d. Wiss.

Berlin," 1866, was chiefly on herbarium specimens. His experimental work

was published in the "Bot. Zeitung," 1871.)

I am particularly obliged for the information and specimens of Cordia

(674/2. Cordiaceae: probably dimorphic.), and shall be most grateful for

seed. I have not heard of any dimorphic species in this family. Hardly

anything in your letter interested me so much as your account and

drawing of the valves of the pod of one of the Mimoseae with the really

beautiful seeds. I will send some of these seeds to Kew to be planted.

But these seeds seem to me to offer a very great difficulty. They do

not seem hard enough to resist the triturating power of the gizzard of a

gallinaceous bird, though they must resist that of some other birds;

for the skin is as hard as ivory. I presume that these seeds cannot

be covered with any attractive pulp? I soaked one of the seeds for ten

hours in warm water, which became only very slightly mucilaginous.

I think I will try whether they will pass through a fowl uninjured.

(674/3. The seeds proved to be those of Adenanthera pavonina. The

solution of the difficulty is given in the following extract from a

letter to Muller, March 2nd, 1867: "I wrote to India on the subject,

and I hear from Mr. J. Scott that parrots are eager for the seeds, and,

wonderful as the fact is, can split them open with their beaks; they

first collect a large number in their beaks, and then settle themselves

to split them, and in doing so drop many; thus I have no doubt they are

disseminated, on the same principle that the acorns of our oaks are most

widely disseminated." Possibly a similar explanation may hold good

for the brightly coloured seeds of Abrus precatorius.) I hope you will

observe whether any bird devours them; and could you get any young man

to shoot some and observe whether the seeds are found low down in

the intestines? It would be well worth while to plant such seeds with

undigested seeds for comparison. An opponent of ours might make a

capital case against us by saying that here beautiful pods and seeds

have been formed not for the good of the plant, but for the good of

birds alone. These seeds would make a beautiful bracelet for one of my

daughters, if I had enough. I may just mention that Euonymus europoeus

is a case in point: the seeds are coated by a thin orange layer, which I

find is sufficient to cause them to be devoured by birds.

I have received your paper on Martha [Posoqueria (674/4. "Bot. Zeitung,"

1866.)]; it is as wonderful as the most wonderful orchis; Ernst Hackel

brought me the paper and stayed a day with me. I have seldom seen a

more pleasant, cordial, and frank man. He is now in Madeira, where he is

going to work chiefly on the Medusae. His great work is now published,

and I have a copy; but the german is so difficult I can make out but

little of it, and I fear it is too large a work to be translated. Your

fact about the number of seeds in the capsule of the Maxillaria (674/5.

See "Animals and Plants," Edition II., Volume II., page 115.) came just

at the right time, as I wished to give one or two such facts. Does this

orchid produce many capsules? I cannot answer your question about the

aerial roots of Catasetum. I hope you have received the new edition

of the "Origin." Your paper on climbing plants (674/6. "Linn. Soc.

Journal," IX., 1867, page 344.) is printed, and I expect in a day or two

to receive the spare copies, and I will send off three copies as before

stated, and will retain some in case you should wish me to send them to

any one in Europe, and will transmit the remainder to yourself.

LETTER 675. TO F. MULLER. Down [received February 24th, 1867].

Your letter of November 2nd contained an extraordinary amount of

interesting matter. What a number of dimorphic plants South Brazil

produces: you observed in one day as many or more dimorphic genera than

all the botanists in Europe have ever observed. When my present book

is finished I shall write a final paper upon these plants, so that I

am extremely glad to hear of your observations and to see the dried

flowers; nevertheless, I should regret MUCH if I prevented you from

publishing on the subject. Plumbago (675/1. Plumbago has not been shown

to be dimorphic.) is quite new to me, though I had suspected it. It is

curious how dimorphism prevails by groups throughout the world,

showing, as I suppose, that it is an ancient character; thus Hedyotis is

dimorphic in India (675/2. Hedyotis was sent to Darwin by F. Muller; it

seems possible, therefore, that Hedyotis was written by mistake for some

other Rubiaceous plant, perhaps Oldenlandia, which John Scott sent him

from India.); the two other genera in the same sub-family with Villarsia

are dimorphic in Europe and Ceylon; a sub-genus of Erythroxylon (675/3.

No doubt Sethia.) is dimorphic in Ceylon, and Oxalis with you and at the

Cape of Good Hope. If you can find a dimorphic Oxalis it will be a new

point, for all known species are trimorphic or monomorphic. The case of

Convolvulus will be new, if proved. I am doubtful about Gesneria (675/4.

Neither Convolvulus nor Gesneria have been shown to be dimorphic.),

and have been often myself deceived by varying length of pistil.

A difference in the size of the pollen-grains would be conclusive

evidence; but in some cases experiments by fertilisation can alone

decide the point. As yet I know of no case of dimorphism in flowers

which are very irregular; such flowers being apparently always

sufficiently visited and crossed by insects.

LETTER 676. TO F. MULLER. Down, April 22nd [1867].

I am very sorry your papers on climbing plants never reached you. They

must be lost, but I put the stamps on myself and I am sure they were

right. I despatched on the 20th all the remaining copies, except one for

myself. Your letter of March 4th contained much interesting matter, but

I have to say this of all your letters. I am particularly glad to hear

that Oncidium flexuosum (676/1. See "Animals and Plants," Edition II.,

Volume II., page 114. Observations on Oncidium were made by John Scott,

and in Brazil by F. Muller, who "fertilised above one hundred flowers of

the above-mentioned Oncidium flexuosum, which is there endemic, with

its own pollen, and with that taken from distinct plants: all the former

were sterile, whilst those fertilised by pollen from any OTHER PLANT of

the same species were fertile.') is endemic, for I always thought that

the cases of self-sterility with orchids in hot-houses might have been

caused by their unnatural conditions. I am glad, also, to hear of the

other analogous cases, all of which I will give briefly in my book

that is now printing. The lessened number of good seeds in the

self-fertilising Epidendrums is to a certain extent a new case.

You suggest the comparison of the growth of plants produced from

self-fertilised and crossed seeds. I began this work last autumn, and

the result, in some cases, has been very striking; but only, as far as

I can yet judge, with exotic plants which do not get freely crossed by

insects in this country. In some of these cases it is really a wonderful

physiological fact to see the difference of growth in the plants

produced from self-fertilised and crossed seeds, both produced by the

same parent-plant; the pollen which has been used for the cross having

been taken from a distinct plant that grew in the same flower-pot. Many

thanks for the dimorphic Rubiaceous plant. Three of your Plumbagos have

germinated, but not as yet any of the Lobelias. Have you ever thought of

publishing a work which might contain miscellaneous observations on all

branches of Natural History, with a short description of the country and

of any excursions which you might take? I feel certain that you might

make a very valuable and interesting book, for every one of your

letters is so full of good observations. Such books, for instance Bates'

"Travels on the Amazons," are very popular in England. I will give your

obliging offer about Brazilian plants to Dr. Hooker, who was to have

come here to-day, but has failed. He is an excellent good fellow, as

well as naturalist. He has lately published a pamphlet, which I think

you would like to read; and I will try and get a copy and send you.

(676/2. Sir J.D. Hooker's lecture on Insular Floras, given before

the British Association in August, 1866, is doubtless referred to. It

appeared in the "Gardeners' Chronicle," and was published as a pamphlet

in January, 1867. This fact helps to fix the date of the present

letter.)

LETTER 677. TO F. MULLER.

(677/1. The following refers to the curious case of Eschscholtzia

described in "Cross and Self-Fertilisation," pages 343-4. The offspring

of English plants after growing for two generations in Brazil became

self-sterile, while the offspring of Brazilian plants became partly

self-fertile in England.)

January 30th [1868].

...The flowers of Eschscholtzia when crossed with pollen from a distinct

plant produced 91 per cent. of capsules; when self-fertilised the

flowers produced only 66 per cent. of capsules. An equal number of

crossed and self-fertilised capsules contained seed by weight in the

proportion of 100 to 71. Nevertheless, the self-fertilised flowers

produced an abundance of seed. I enclose a few crossed seeds in hopes

that you will raise a plant, cover it with a net, and observe whether it

is self-fertile; at the same time allowing several uncovered plants to

produce capsules, for the sterility formerly observed by you seems to me

very curious.

LETTER 678. TO F. MULLER. Down, November 28th [1868].

You end your letter of September 9th by saying that it is a very

dull one; indeed, you make a very great mistake, for it abounds with

interesting facts and thoughts. Your account of the tameness of the

birds which apparently have wandered from the interior, is very curious.

But I must begin on another subject: there has been a great and very

vexatious, but unavoidable delay in the publication of your book.

(678/1. "Facts and Arguments for Darwin," 1869, a translation by the

late Mr. Dallas of F. Muller's "Fur Darwin," 1864: see Volume I., Letter

227.) Prof. Huxley agrees with me that Mr. Dallas is by far the best

translator, but he is much overworked and had not quite finished the

translation about a fortnight ago. He has charge of the Museum at York,

and is now trying to get the situation of Assistant Secretary at the

Geological Society; and all the canvassing, etc., and his removal, if

he gets the place, will, I fear, cause more than a month's delay in the

completion of the translation; and this I very much regret.

I am particularly glad to hear that you intend to repeat my experiments

on illegitimate offspring, for no one's observations can be trusted

until repeated. You will find the work very troublesome, owing to the

death of plants and accidents of all kinds. Some dimorphic plant will

probably prove too sterile for you to raise offspring; and others too

fertile for much sterility to be expected in their offspring. Primula

is bad on account of the difficulty of deciding which seeds may be

considered as good. I have earnestly wished that some one would repeat

these experiments, but I feared that years would elapse before any

one would take the trouble. I received your paper on Bignonia in "Bot.

Zeit." and it interested me much. (678/2. See "Variation of Animals

and Plants," Edition II., Volume II., page 117. Fritz Muller's paper,

"Befruchtungsversuche an Cipo alho (Bignonia)," "Botanische Zeitung,"

September 25th, 1868, page 625, contains an interesting foreshadowing of

the generalisation arrived at in "Cross and Self-Fertilisation." Muller

wrote: "Are the three which grow near each other seedlings from the same

mother-plant or perhaps from seeds of the same capsule? Or have they,

from growing in the same place and under the same conditions, become so

like each other that the pollen of one has hardly any more effect on

the others than their own pollen? Or, on the contrary, were the plants

originally one--i.e., are they suckers from a single stock, which

have gained a slight degree of mutual fertility in the course of an

independent life? Or, lastly, is the result 'ein neckische Zufall,'"

(The above is a free translation of Muller's words.)) I am convinced

that if you can prove that a plant growing in a distant place under

different conditions is more effective in fertilisation than one

growing close by, you will make a great step in the essence of sexual

reproduction.

Prof. Asa Gray and Dr. Hooker have been staying here, and, oddly

enough, they knew nothing of your paper on Martha (678/3. F. Muller has

described ("Bot. Zeitung," 1866, page 129) the explosive mechanism by

which the pollen is distributed in Martha (Posoqueria) fragrans. He

also gives an account of the remarkable arrangement for ensuring

cross-fertilisation. See "Forms of Flowers," Edition II., page 131.),

though the former was aware of the curious movements of the stamens, but

so little understood the structure of the plant that he thought it was

probably a dimorphic species. Accordingly, I showed them your drawings

and gave them a little lecture, and they were perfectly charmed with

your account. Hildebrand (678/4. See Letter 206, Volume I.) has repeated

his experiments on potatoes, and so have I, but this summer with no

result.

LETTER 679. TO F. MULLER. Down, March 14th [1869].

I received some time ago a very interesting letter from you with many

facts about Oxalis, and about the non-seeding and spreading of one

species. I may mention that our common O. acetosella varies much

in length of pistils and stamens, so that I at first thought it was

certainly dimorphic, but proved it by experiment not to be so. Boiseria

(679/1. This perhaps refers to Boissiera (Ladizabala).) has after all

seeded well with me when crossed by opposite form, but very sparingly

when self-fertilised. Your case of Faramea astonishes me. (679/2. See

"Forms of Flowers," Edition II., page 129. Faramea is placed among the

dimorphic species.) Are you sure there is no mistake? The difference

in size of flower and wonderful difference in size and structure of

pollen-grains naturally make me rather sceptical. I never fail to admire

and to be surprised at the number of points to which you attend. I go

on slowly at my next book, and though I never am idle, I make but slow

progress; for I am often interrupted by being unwell, and my subject

of sexual selection has grown into a very large one. I have also had

to correct a new edition of my "Origin," (679/3. The 5th edition.), and

this has taken me six weeks, for science progresses at railroad speed.

I cannot tell you how rejoiced I am that your book is at last out; for

whether it sells largely or not, I am certain it will produce a great

effect on all capable judges, though these are few in number.

P.S.--I have just received your letter of January 12th. I am greatly

interested by what you say on Eschscholtzia; I wish your plants had

succeeded better. It seems pretty clear that the species is much more

self-sterile under the climate of Brazil than here, and this seems to me

an important result. (679/4. See Letter 677.) I have no spare seeds at

present, but will send for some from the nurseryman, which, though not

so good for our purpose, will be worth trying. I can send some of my own

in the autumn. You could simply cover up separately two or three single

plants, and see if they will seed without aid,--mine did abundantly.

Very many thanks for seeds of Oxalis: how I wish I had more strength and

time to carry on these experiments, but when I write in the morning, I

have hardly heart to do anything in the afternoon. Your grass is most

wonderful. You ought to send account to the "Bot. Zeitung." Could you

not ascertain whether the barbs are sensitive, and how soon they

become spiral in the bud? Your bird is, I have no doubt, the Molothrus

mentioned in my "Journal of Travels," page 52, as representing a North

American species, both with cuckoo-like habits. I know that seeds from

same spike transmitted to a certain extent their proper qualities; but

as far as I know, no one has hitherto shown how far this holds good, and

the fact is very interesting. The experiment would be well worth trying

with flowers bearing different numbers of petals. Your explanation

agrees beautifully with the hypothesis of pangenesis, and delights me.

If you try other cases, do draw up a paper on the subject of inheritance

of separate flowers for the "Bot. Zeitung" or some journal. Most men,

as far as my experience goes, are too ready to publish, but you seem

to enjoy making most interesting observations and discoveries, and are

sadly too slow in publishing.

LETTER 680. TO F. MULLER. Barmouth, July 18th, 1869.

I received your last letter shortly before leaving home for this place.

Owing to this cause and to having been more unwell than usual I have

been very dilatory in writing to you. When I last heard, about six or

eight weeks ago, from Mr. Murray, one hundred copies of your book had

been sold, and I daresay five hundred may now be sold. (680/1. "Facts

and Arguments for Darwin," 1869: see Volume I., Letter 227.) This will

quite repay me, if not all the money; for I am sure that your book will

have got into the hands of a good many men capable of understanding it:

indeed, I know that it has. But it is too deep for the general public.

I sent you two or three reviews--one of which, in the "Athenaeum," was

unfavourable; but this journal has abused me, and all who think with me,

for many years. (680/2. "Athenaeum," 1869, page 431.) I enclose two more

notices, not that they are worth sending: some other brief notices have

appeared. The case of the Abitulon sterile with some individuals is

remarkable (680/3. "Bestaubungsversuche an Abutilon-Arten." "Jenaische

Zeitschr." VII., 1873, page 22.): I believe that I had one plant of

Reseda odorata which was fertile with own pollen, but all that I have

tried since were sterile except with pollen from some other individual.

I planted the seeds of the Abitulon, but I fear that they were crushed

in the letter. Your Eschscholtzia plants were growing well when I left

home, to which place we shall return by the end of this month, and I

will observe whether they are self-sterile. I sent your curious account

of the monstrous Begonia to the Linnean Society, and I suppose it will

be published in the "Journal." (680/4. "On the Modification of the

Stamens in a Species of Begonia." "Journ. Linn. Soc." XI., 1871, page

472.) I sent the extract about grafted orange trees to the "Gardeners'

Chronicle," where it appeared. I have lately drawn up some notes for a

French translation of my Orchis book: I took out your letters to make an

abstract of your numerous discussions, but I found I had not strength

or time to do so, and this caused me great regret. I have [in the French

edition] alluded to your work, which will also be published in English,

as you will see in my paper, and which I will send you. (680/5. "Notes

on the Fertilisation of Orchids." "Ann. Mag. Nat. Hist." 1869, Volume

IV., page 141. The paper gives an English version of the notes prepared

for the French edition of the Orchid book.)

P.S.--By an odd chance, since I wrote the beginning of this letter, I

have received one from Dr. Hooker, who has been reading "Fur Darwin": he

finds that he has not knowledge enough for the first part; but says

that Chapters X. and XI. "strike me as remarkably good." He is also

particularly struck with one of your highly suggestive remarks in the

note to page 119. Assuredly all who read your book will greatly profit

by it, and I rejoice that it has appeared in English.

LETTER 681. TO F. MULLER. Down, December 1st [1869].

I am much obliged for your letter of October 18th, with the curious

account of Abutilon, and for the seeds. A friend of mine, Mr. Farrer,

has lately been studying the fertilisation of Passiflora (681/1. See

Letters 701 and 704.), and concluded from the curiously crooked passage

into the nectary that it could not be fertilised by humming-birds; but

that Tacsonia was thus fertilised. Therefore I sent him the passage from

your letter, and I enclose a copy of his answer. If you are inclined to

gratify him by making a few observations on this subject I shall be

much obliged, and will send them on to him. I enclose a copy of my rough

notes on your Eschscholtzia, as you might like to see them. Somebody has

sent me from Germany two papers by you, one with a most curious account

of Alisma (681/2. See Letter 672.), and the other on crustaceans. Your

observations on the branchiae and heart have interested me extremely.

Alex. Agassiz has just paid me a visit with his wife. He has been in

England two or three months, and is now going to tour over the Continent

to see all the zoologists. We liked him very much. He is a great admirer

of yours, and he tells me that your correspondence and book first

made him believe in evolution. This must have been a great blow to his

father, who, as he tells me, is very well, and so vigorous that he can

work twice as long as he (the son) can.

Dr. Meyer has sent me his translation of Wallace's "Malay Archipelago,"

which is a valuable work; and as I have no use for the translation,

I will this day forward it to you by post, but, to save postage, via

England.

LETTER 682. TO F. MULLER. Down, May 12th [1870].

I thank you for your two letters of December 15th and March 29th, both

abounding with curious facts. I have been particularly glad to hear in

your last about the Eschscholtzia (682/1. See Letter 677.); for I am now

rearing crossed and self-fertilised plants, in antagonism to each other,

from your semi-sterile plants so that I may compare this comparative

growth with that of the offspring of English fertile plants. I have

forwarded your postscript about Passiflora, with the seeds, to Mr.

Farrer, who I am sure will be greatly obliged to you; the turning up of

the pendant flower plainly indicates some adaptation. When I next go to

London I will take up the specimens of butterflies, and show them to

Mr. Butler, of the British Museum, who is a learned lepidopterist

and interested on the subject. This reminds me to ask you whether you

received my letter [asking] about the ticking butterfly, described at

page 33 of my "Journal of Researches"; viz., whether the sound is in

anyway sexual? Perhaps the species does not inhabit your island. (682/2.

Papilio feronia, a Brazilian species capable of making "a clicking

noise, similar to that produced by a toothed wheel passing under a

spring catch."--"Journal," 1879, page 34.)

The case described in your last letter of the trimorphic monocotyledon

Pontederia is grand. (682/3. This case interested Darwin as the only

instance of heterostylism in Monocotyledons. See "Forms of Flowers,"

Edition II., page 183. F. Muller's paper is in the "Jenaische

Zeitschrift," 1871.) I wonder whether I shall ever have time to recur

to this subject; I hope I may, for I have a good deal of unpublished

material.

Thank you for telling me about the first-formed flower having additional

petals, stamens, carpels, etc., for it is a possible means of transition

of form; it seems also connected with the fact on which I have insisted

of peloric flowers being so often terminal. As pelorism is strongly

inherited (and [I] have just got a curious case of this in a leguminous

plant from India), would it not be worth while to fertilise some of

your early flowers having additional organs with pollen from a similar

flower, and see whether you could not make a race thus characterised?

(682/4. See Letters 588, 589. Also "Variation under Domestication,"

Edition II., Volume I., pages 388-9.) Some of your Abutilons have

germinated, but I have been very unfortunate with most of your seed.

You will remember having given me in a former letter an account of

a very curious popular belief in regard to the subsequent progeny

of asses, which have borne mules; and now I have another case almost

exactly like that of Lord Morton's mare, in which it is said the shape

of the hoofs in the subsequent progeny are affected. (Pangenesis will

turn out true some day!) (682/5. See "Animals and Plants," Edition

II., Volume I., page 435. For recent work on telegony see Ewart's

"Experimental Investigations on Telegony," "Phil. Trans. R. Soc." 1899.

A good account of the subject is given in the "Quarterly Review," 1899,

page 404. See also Letter 275, Volume I.)

A few months ago I received an interesting letter and paper from your

brother, who has taken up a new and good line of investigation, viz.,

the adaptation in insects for the fertilisation of flowers.

The only scientific man I have seen for several months is Kolliker, who

came here with Gunther, and whom I liked extremely.

I am working away very hard at my book on man and on sexual selection,

but I do not suppose I shall go to press till late in the autumn.