Volume I., page 443.) I should be most grateful for information. I may

add that if you have observed in your enormous experience any remarkable

"bud-variations," and could spare time to inform me, and allow me to

quote them on your authority, it would be the greatest favour. I

feel sure that these "bud-variations" are most interesting to any one

endeavouring to make out what little can be made out on the obscure

subject of variation.

LETTER 196. TO T. RIVERS. Down, January 7th [1867?].

I thank you much for your letter and the parcel of shoots. The case

of the yellow plum is a treasure, and is now safely recorded on your

authority in its proper place, in contrast with A. Knight's case of

the yellow magnum bonum sporting into red. (196/1. See "Variation

under Domestication," Edition II., Volume I., page 399.) I could see no

difference in the shoots, except that those of the yellow were thicker,

and I presume that this is merely accidental: as you do not mention it,

I further presume that there are no further differences in leaves or

flowers of the two plums. I am very glad to hear about the yellow ash,

and that you yourself have seen the jessamine case. I must confess that

I hardly fully believed in it; but now I do, and very surprising it is.

In an old French book, published in Amsterdam in 1786 (I think), there

is an account, apparently authentic and attested by the writer as an

eye-witness, of hyacinth bulbs of two colours being cut in two and

grafted, and they sent up single stalks with differently coloured

flowers on the two sides, and some flowers parti-coloured. I once

thought of offering 5 pounds reward in the "Cottage Gardener" for such a

plant; but perhaps it would seem too foolish. No instructions are given

when to perform the operation; I have tried two or three times, and

utterly failed. I find that I have a grand list of "bud-variations," and

to-morrow shall work up such cases as I have about rose-sports, which

seem very numerous, and which I see you state to occur comparatively

frequently.

When a person is very good-natured he gets much pestered--a discovery

which I daresay you have made, or anyhow will soon make; for I do want

very much to know whether you have sown seed of any moss-roses, and

whether the seedlings were moss-roses. (196/2. Moss-roses can be raised

from seed ("Variation under Domestication," Edition II., Volume I., page

405.) Has a common rose produced by SEED a moss-rose?

If any light comes to you about very slight changes in the buds, pray

have the kindness to illuminate me. I have cases of seven or eight

varieties of the peach which have produced by "bud-variation"

nectarines, and yet only one single case (in France) of a peach

producing another closely similar peach (but later in ripening). How

strange it is that a great change in the peach should occur not rarely

and slighter changes apparently very rarely! How strange that no case

seems recorded of new apples or pears or apricots by "bud-variation"!

How ignorant we are! But with the many good observers now living our

children's children will be less ignorant, and that is a comfort.

LETTER 197. TO T.H. HUXLEY. Down, January 7th [1867].

Very many thanks for your letter, which has told me exactly what I

wanted to know. I shall give up all thoughts of trying to get the book

(197/1. Hackel's "Generelle Morphologie," 1866. See "Life and Letters,"

III., pages 67, 68.) translated, for I am well convinced that it would

be hopeless without too great an outlay. I much regret this, as I should

think the work would be useful, and I am sure it would be to me, as I

shall never be able to wade through more than here and there a page of

the original. To all people I cannot but think that the number of new

terms would be a great evil. I must write to him. I suppose you know

his address, but in case you do not, it is "to care of Signor Nicolaus

Krohn, Madeira." I have sent the MS. of my big book (197/2. "The

Variation of Animals and Plants under Domestication," 1868.), and

horridly, disgustingly big it will be, to the printers, but I do not

suppose it will be published, owing to Murray's idea on seasons, till

next November. I am thinking of a chapter on Man, as there has lately

been so much said on Natural Selection in relation to man. I have not

seen the Duke's (or Dukelet's? how can you speak so of a living real

Duke?) book, but must get it from Mudie, as you say he attacks us.

(197/3. "The Reign of Law" (1867), by the late Duke of Argyll. See "Life

and Letters," III., page 65.)

P.S.--Nature never made species mutually sterile by selection, nor will

men.

LETTER 197. TO E. HACKEL. Down, January 8th [1867].

I received some weeks ago your great work (198/1. "Generelle

Morphologie," 1866.); I have read several parts, but I am too poor a

German scholar and the book is too large for me to read it all. I cannot

tell you how much I regret this, for I am sure that nearly the whole

would interest me greatly, and I have already found several parts very

useful, such as the discussion on cells and on the different forms of

reproduction. I feel sure, after considering the subject deliberately

and after consulting with Huxley, that it would be hopeless to endeavour

to get a publisher to print an English translation; the work is too

profound and too long for our English countrymen. The number of new

terms would also, I am sure, tell much against its sale; and, indeed,

I wish for my own sake that you had printed a glossary of all the

new terms which you use. I fully expect that your book will be highly

successful in Germany, and the manner in which you often refer to me in

your text, and your dedication and the title, I shall always look at as

one of the greatest honours conferred on me during my life. (198/2. As

regards the dedication and title this seems a strong expression. The

title is "Generelle Morphologie der Organismen. Allgemeine Grundzuge

der organischen Formen-Wissenschaft mechanisch begrundet durch die von

Charles Darwin reformirte Descendenz-Theorie." The dedication of the

second volume is "Den Begrundern der Descendenz-Theorie, den denkenden

Naturforschern, Charles Darwin, Wolfgang Goethe, Jean Lamarck widmet

diese Grundzuge der Allgemeinen Entwickelungsgeschichte in vorzuglicher

Verehrung, der Verfasser.")

I sincerely hope that you have had a prosperous expedition, and have met

with many new and interesting animals. If you have spare time I should

much like to hear what you have been doing and observing. As for

myself, I have sent the MS. of my book on domestic animals, etc., to the

printers. It turns out to be much too large; it will not be published,

I suppose, until next November. I find that we have discussed several

of the same subjects, and I think we agree on most points fairly well.

I have lately heard several times from Fritz Muller, but he seems now

chiefly to be working on plants. I often think of your visit to this

house, which I enjoyed extremely, and it will ever be to me a real

pleasure to remember our acquaintance. From what I heard in London I

think you made many friends there. Shall you return through England?

If so, and you can spare the time, we shall all be delighted to see you

here again.

LETTER 199. TO T. RIVERS. Down, January 11th [1867?].

How rich and valuable a letter you have most kindly sent me! The case

of Baronne Prevost (199/1. See "Variation under Domestication," Edition

II., Volume I., page 406. Mr. Rivers had a new French rose with a

delicate smooth stem, pale glaucous leaves and striped flesh-coloured

flowers; on branches thus characterised there appeared "the famous old

rose called 'Baronne Prevost,'" with its stout thorny stem and uniform

rich-coloured double flowers.), with its different shoots, foliage,

spines, and flowers, will be grand to quote. I am extremely glad to hear

about the seedling moss-roses. That case of a seedling like a Scotch

rose, unless you are sure that no Scotch rose grew near (and it is

unlikely that you can remember), must, one would think, have been a

cross.

I have little compunction for being so troublesome--not more than a

grand Inquisitor has in torturing a heretic--for am I not doing a real

good public service in screwing crumbs of knowledge out of your wealth

of information?

P.S. Since the above was written I have read your paper in the

"Gardeners' Chronicle": it is admirable, and will, I know, be a treasure

to me. I did not at all know how strictly the character of so many

flowers is inherited.

On my honour, when I began this note I had no thought of troubling you

with a question; but you mention one point so interesting, and which I

have had occasion to notice, that I must supplicate for a few more facts

to quote on your authority. You say that you have one or two seedling

peaches (199/2. "On raising Peaches, Nectarines, and other Fruits from

Seed." By Thomas Rivers, Sawbridgeworth.--"Gard. Chron." 1866, page

731.) approaching very nearly to thick-fleshed almonds (I know about A.

Knight and the Italian hybrid cases). Now, did any almond grow near your

mother peach? But especially I want to know whether you remember what

shape the stone was, whether flattened like that of an almond; this,

botanically, seems the most important distinction. I earnestly wish to

quote this. Was the flesh at all sweet?

Forgive if you can.

Have you kept these seedling peaches? if you would give me next summer a

fruit, I want to have it engraved.

LETTER 200. TO I. ANDERSON-HENRY. May 22nd [1867].

You are so kind as to offer to lend me Maillet's (200/1. For De Maillet

see Mr. Huxley's review on "The Origin of Species" in the "Westminster

Review," 1860, reprinted in "Lay Sermons," 1870, page 314. De Maillet's

evolutionary views were published after his death in 1748 under the name

of Telliamed (De Maillet spelt backwards).) work, which I have often

heard of, but never seen. I should like to have a look at it, and would

return it to you in a short time. I am bound to read it, as my former

friend and present bitter enemy Owen generally ranks me and Maillet as a

pair of equal fools.

LETTER 201. TO J.D. HOOKER. Down, April 4th [1867].

You have done me a very great service in sending me the pages of the

"Farmer." I do not know whether you wish it returned; but I will keep

it unless I hear that you want it. Old I. Anderson-Henry passes a

magnificent but rather absurd eulogium on me; but the point of such

extreme value in my eyes is Mr. Traill's (201/1. Mr. Traill's results

are given at page 420 of "Animals and Plants," Edition II., Volume I.

In the "Life and Letters of G.J. Romanes," 1896, an interesting

correspondence is published with Mr. Darwin on this subject. The plan

of the experiments suggested to Romanes was to raise seedlings from

graft-hybrids: if the seminal offspring of plants hybridised by grafting

should show the hybrid character, it would be striking evidence in

favour of pangenesis. The experiment, however, did not succeed.)

statement that he made a mottled mongrel by cutting eyes through

and joining two kinds of potatoes. (201/2. For an account of similar

experiments now in progress, see a "Note on some Grafting Experiments"

by R. Biffen in the "Annals of Botany," Volume XVI., page 174, 1902.) I

have written to him for full information, and then I will set to work

on a similar trial. It would prove, I think, to demonstration that

propagation by buds and by the sexual elements are essentially the same

process, as pangenesis in the most solemn manner declares to be the

case.

LETTER 202. TO T.H. HUXLEY. Down, June 12th [1867?].

We come up on Saturday, the 15th, for a week. I want much to see you for

a short time to talk about my youngest boy and the School of Mines. I

know it is rather unreasonable, but you must let me come a little after

10 o'clock on Sunday morning, the 16th. If in any way inconvenient, send

me a line to "6, Queen Anne Street W.,"; but if I do not hear, I will

(stomacho volente) call, but I will not stay very long and spoil your

whole morning as a holiday. Will you turn two or three times in your

mind this question: what I called "pangenesis" means that each cell

throws off an atom of its contents or a gemmule, and that these

aggregated form the true ovule or bud, etc.? Now I want to know

whether I could not invent a better word. "Cyttarogenesis" (202/1. From

kuttaros, a bee's-cell: cytogenesis would be a natural form of the word

from kutos.)--i.e. cell-genesis--is more true and expressive, but long.

"Atomogenesis" sounds rather better, I think, but an "atom" is an object

which cannot be divided; and the term might refer to the origin of

atoms of inorganic matter. I believe I like "pangenesis" best, though

so indefinite; and though my wife says it sounds wicked, like pantheism;

but I am so familiar now with this word, that I cannot judge. I

supplicate you to help me.

LETTER 203. TO A.R. WALLACE. Down, October, 12th and 13th [1867].

I ordered the journal (203/1. "Quarterly Journal of Science," October,

1867, page 472. A review of the Duke of Argyll's "Reign of Law.") a long

time ago, but by some oversight received it only yesterday, and read it.

You will think my praise not worth having, from being so indiscriminate;

but if I am to speak the truth, I must say I admire every word. You have

just touched on the points which I particularly wished to see noticed.

I am glad you had the courage to take up Angraecum (203/2. Angraecum

sesquipedale, a Madagascan orchid, with a whiplike nectary, 11 to

12 inches in length, which, according to Darwin ("Fertilisation of

Orchids," Edition II., page 163), is adapted to the visits of a moth

with a proboscis of corresponding length. He points out that there is no

difficulty in believing in the existence of such a moth as F. Muller

has described ("Nature," 1873, page 223)--a Brazilian sphinx-moth with a

trunk of 10 to 11 inches in length. Moreover, Forbes has given evidence

to show that such an insect does exist in Madagascar ("Nature," VIII.,

1873, page 121). The case of Angraecum was put forward by the Duke

of Argyll as being necessarily due to the personal contrivance of the

Deity. Mr. Wallace (page 476) shows that both proboscis and nectary

might be increased in length by means of Natural Selection. It may be

added that Hermann Muller has shown good grounds for believing that

mutual specialisation of this kind is beneficial both to insect and

plant.) after the Duke's attack; for I believe the principle in this

case may be widely applied. I like the figure, but I wish the artist had

drawn a better sphinx. With respect to beauty, your remarks on hideous

objects and on flowers not being made beautiful except when of practical

use to them, strike me as very good. On this one point of beauty I

can hardly think that the Duke was quite candid. I have used in the

concluding paragraph of my present book precisely the same argument as

you have, even bringing in the bull-dog (203/3. "Variation of Animals

and Plants," Edition I., Volume II., page 431: "Did He cause the frame

and mental qualities of the dog to vary in order that a breed might be

formed of indomitable ferocity, with jaws fitted to pin down the bull

for man's brutal sport?"), with respect to variations not having been

specially ordained. Your metaphor of the river (203/4. See Wallace,

op. cit., pages 477-8. He imagines an observer examining a great

river-system, and finding everywhere adaptations which reveal the design

of the Creator. "He would see special adaptation to the wants of man

in broad, quiet, navigable rivers, through fertile alluvial plains that

would support a large population, while the rocky streams and mountain

torrents were confined to those sterile regions suitable only for

a small population of shepherds and herdsmen.') is new to me, and

admirable; but your other metaphor, in which you compare classification

and complex machines, does not seem to me quite appropriate, though

I cannot point out what seems deficient. The point which seems to

me strong is that all naturalists admit that there is a natural

classification, and it is this which descent explains. I wish you had

insisted a little more against the "North British" (203/5. At page 485

Mr. Wallace deals with Fleeming Jenkin's review in the "North British

Review," 1867. The review strives to show that there are strict limits

to variation, since the most rigorous and long-continued selection

does not indefinitely increase such a quality as the fleetness of a

racehorse. On this Mr. Wallace remarks that "this argument fails to meet

the real question," which is, not whether indefinite change is possible,

"but whether such differences as do occur in nature could have been

produced by the accumulation of variations by selection.") on the

reviewer assuming that each variation which appears is a strongly marked

one; though by implication you have made this very plain. Nothing in

your whole article has struck me more than your view with respect to the

limit of fleetness in the racehorse and other such cases: I shall try

and quote you on this head in the proof of my concluding chapter. I

quite missed this explanation, though in the case of wheat I hit upon

something analogous. I am glad you praise the Duke's book, for I was

much struck with it. The part about flight seemed to me at first very

good; but as the wing is articulated by a ball-and-socket joint, I

suspect the Duke would find it very difficult to give any reason against

the belief that the wing strikes the air more or less obliquely. I have

been very glad to see your article and the drawing of the butterfly

in "Science Gossip." By the way, I cannot but think that you push

protection too far in some cases, as with the stripes on the tiger. I

have also this morning read an excellent abstract in the "Gardeners'

Chronicle" of your paper on nests. (203/6. An abstract of a paper on

"Birds' Nests and Plumage," read before the British Association: see

"Gard. Chron." 1867, page 1047.) I was not by any means fully converted

by your letter, but I think now I am so; and I hope it will be published

somewhere in extenso. It strikes me as a capital generalisation, and

appears to me even more original than it did at first...

I have finished Volume I. of my book ["Variation of Animals and

Plants"], and I hope the whole will be out by the end of November. If

you have the patience to read it through, which is very doubtful, you

will find, I think, a large accumulation of facts which will be of

service to you in future papers; and they could not be put to better

use, for you certainly are a master in the noble art of reasoning.

LETTER 204. TO T.H. HUXLEY. Down, October 3rd [no date].

I know you have no time for speculative correspondence; and I did not

in the least expect an answer to my last. But I am very glad to have

had it, for in my eclectic work the opinions of the few good men are of

great value to me.

I knew, of course, of the Cuvierian view of classification (204/1.

Cuvier proved that "animals cannot be arranged in a single series, but

that there are several distinct plans of organisation to be observed

among them, no one of which, in its highest and most complicated

modification, leads to any of the others" (Huxley's "Darwiniana," page

215).); but I think that most naturalists look for something further,

and search for "the natural system,"--"for the plan on which the Creator

has worked," etc., etc. It is this further element which I believe to be

simply genealogical.

But I should be very glad to have your answer (either when we meet or by

note) to the following case, taken by itself, and not allowing yourself

to look any further than to the point in question. Grant all races of

man descended from one race--grant that all the structure of each race

of man were perfectly known--grant that a perfect table of the descent

of each race was perfectly known--grant all this, and then do you not

think that most would prefer as the best classification, a genealogical

one, even if it did occasionally put one race not quite so near to

another, as it would have stood, if collocated by structure alone?

Generally, we may safely presume, that the resemblance of races and

their pedigrees would go together.

I should like to hear what you would say on this purely theoretical

case.

It might be asked why is development so all-potent in classification,

as I fully admit it is? I believe it is because it depends on, and best

betrays, genealogical descent; but this is too large a point to enter

on.

LETTER 205. TO C. LYELL. Down, December 7th [1867].

I send by this post the article in the Victorian Institute with respect

to frogs' spawn. If you remember in your boyhood having ever tried to

take a small portion out of the water, you will remember that it is most

difficult. I believe all the birds in the world might alight every day

on the spawn of batrachians, and never transport a single ovum. With

respect to the young of molluscs, undoubtedly if the bird to which they

were attached alighted on the sea, they would be instantly killed; but

a land-bird would, I should think, never alight except under dire

necessity from fatigue. This, however, has been observed near Heligoland

(205/1. Instances are recorded by Gatke in his "Heligoland as an

Ornithological Observatory" (translated by Rudolph Rosenstock,

Edinburgh, 1895) of land-birds, such as thrushes, buntings, finches,

etc., resting for a short time on the surface of the water. The

author describes observations made by himself about two miles west of

Heligoland (page 129).); and land-birds, after resting for a time on the

tranquil sea, have been seen to rise and continue their flight. I cannot

give you the reference about Heligoland without much searching. This

alighting on the sea may aid you in your unexpected difficulty of the

too-easy diffusion of land-molluscs by the agency of birds. I much

enjoyed my morning's talk with you.

LETTER 206. TO F. HILDEBRAND. Down, January 5th [1868].

I thank you for your letter, which has quite delighted me. I sincerely

congratulate you on your success in making a graft-hybrid (206/1. Prof.

Hildebrand's paper is in the "Bot. Zeitung," 1868: the substance is

given in "Variation of Animals and Plants," Edition II., Volume I., page

420.), for I believe it to be a most important observation. I trust that

you will publish full details on this subject and on the direct action

of pollen (206/2. See Prof. Hildebrand, "Bot. Zeitung," 1868, and

"Variation of Animals and Plants," Edition II., Volume I., page 430.

A yellow-grained maize was fertilised with pollen from a brown-grained

one; the result was that ears were produced bearing both yellow and

dark-coloured grains.): I hope that you will be so kind as to send me a

copy of your paper. If I had succeeded in making a graft-hybrid of the

potato, I had intended to raise seedlings from the graft-hybrid and

from the two parent-forms (excluding insects) and carefully compare the

offspring. This, however, would be difficult on account of the sterility

and variability of the potato. When in the course of a few months you

receive my second volume (206/3. This sentence may be paraphrased--"When

you receive my book and read the second volume."), you will see why

I think these two subjects so important. They have led me to form

a hypothesis on the various forms of reproduction, development,

inheritance, etc., which hypothesis, I believe, will ultimately be

accepted, though how it will be now received I am very doubtful.

Once again I congratulate you on your success.

LETTER 207. TO J.D. HOOKER. Down, January 6th [1868].

Many thanks about names of plants, synonyms, and male flowers--all that

I wanted.

I have been glad to see Watson's letter, and am sorry he is a renegade

about Natural Selection. It is, as you say, characteristic, with the

final fling at you.

His difficulty about the difference between the two genera of St. Helena

Umbellifers is exactly the same as what Nageli has urged in an able

pamphlet (207/1. "Ueber Entstehung und Begriff der naturhist. Art."

"Sitz. der K. Bayer. Akad. Der Wiss. zu Munchen," 1865. Some of Nageli's

points are discussed in the "Origin," Edition V., page 151.), and who

in consequence maintains that there is some unknown innate tendency to

progression in all organisms. I said in a letter to him that of course I

could not in the least explain such cases; but that they did not seem

to me of overwhelming force, as long as we are quite ignorant of the

meaning of such structures, whether they are of any service to the

plants, or inevitable consequences of modifications in other parts.

I cannot understand what Watson means by the "counter-balance in nature"

to divergent variation. There is the counterbalance of crossing,

of which my present work daily leads me to see more and more the

efficiency; but I suppose he means something very different. Further, I

believe variation to be divergent solely because diversified forms can

best subsist. But you will think me a bore.

I enclose half a letter from F. Muller (which please return) for the

chance of your liking to see it; though I have doubted much about

sending it, as you are so overworked. I imagine the Solanum-like flower

is curious.

I heard yesterday to my joy that Dr. Hildebrand has been experimenting

on the direct action of pollen on the mother-plant with success. He has

also succeeded in making a true graft-hybrid between two varieties of

potatoes, in which I failed. I look at this as splendid for pangenesis,

as being strong evidence that bud-reproduction and seminal reproduction

do not essentially differ.

My book is horribly delayed, owing to the accursed index-maker. (207/2.

Darwin thoroughly appreciated the good work put into the index of "The

Variation of Animals and Plants.") I have almost forgotten it!

LETTER 208. TO T.H. HUXLEY. Down, January 30th [1868].

Most sincere thanks for your kind congratulations. I never received a

note from you in my life without pleasure; but whether this will be so

after you have read pangenesis (208/1. In Volume II. of "Animals and

Plants, 1868.), I am very doubtful. Oh Lord, what a blowing up I may

receive! I write now partly to say that you must not think of looking

at my book till the summer, when I hope you will read pangenesis, for I

care for your opinion on such a subject more than for that of any other

man in Europe. You are so terribly sharp-sighted and so confoundedly

honest! But to the day of my death I will always maintain that you have

been too sharp-sighted on hybridism; and the chapter on the subject in

my book I should like you to read: not that, as I fear, it will produce

any good effect, and be hanged to you.

I rejoice that your children are all pretty well. Give Mrs. Huxley the

enclosed (208/2. Queries on Expression.), and ask her to look out when

one of her children is struggling and just going to burst out crying. A

dear young lady near here plagued a very young child for my sake, till

it cried, and saw the eyebrows for a second or two beautifully oblique,

just before the torrent of tears began.

The sympathy of all our friends about George's success (it is the young

Herald) (208/3. His son George was Second Wrangler in 1868; as a boy

he was an enthusiast in heraldry.) has been a wonderful pleasure to

us. George has not slaved himself, which makes his success the more

satisfactory. Farewell, my dear Huxley, and do not kill yourself with

work.

(209/1. The following group of letters deals with the problem of the

causes of the sterility of hybrids. Mr. Darwin's final view is given in

the "Origin," sixth edition (page 384, edition 1900). He acknowledges

that it would be advantageous to two incipient species, if by

physiological isolation due to mutual sterility, they could be kept from

blending: but he continues, "After mature reflection it seems to me

that this could not have been effected through Natural Selection." And

finally he concludes (page 386):--

"But it would be superfluous to discuss this question in detail; for

with plants we have conclusive evidence that the sterility of crossed

species must be due to some principle quite independent of Natural

Selection. Both Gartner and Kolreuter have proved that in genera

including numerous species, a series can be formed from species which

when crossed yield fewer and fewer seeds, to species which never produce

a single seed, but yet are affected by the pollen of certain other

species, for the germen swells. It is here manifestly impossible to

select the more sterile individuals, which have already ceased to

yield seeds; so that this acme of sterility, when the germen alone is

affected, cannot have been gained through selection; and from the laws

governing the various grades of sterility being so uniform throughout

the animal and vegetable kingdoms, we may infer that the cause, whatever

it may be, is the same or nearly the same in all cases."

Mr. Wallace, on the other hand, still adheres to his view: see his

"Darwinism," 1889, page 174, and for a more recent statement see page

292, note 1, Letter 211, and page 299.

The discussion of 1868 began with a letter from Mr. Wallace, written

towards the end of February, giving his opinion on the "Variation of

Animals and Plants;" the discussion on the sterility of hybrids is at

page 185, Volume II., of the first edition.)

LETTER 209. A.R. WALLACE TO CHARLES DARWIN. February 1868.

The only parts I have yet met with where I somewhat differ from your

views, are in the chapter on the causes of variability, in which I think

several of your arguments are unsound: but this is too long a subject

to go into now. Also, I do not see your objection to sterility between

allied species having been aided by Natural Selection. It appears to me

that, given a differentiation of a species into two forms, each of which

was adapted to a special sphere of existence, every slight degree of

sterility would be a positive advantage, not to the individuals who

were sterile, but to each form. If you work it out, and suppose the

two incipient species a...b to be divided into two groups, one of which

contains those which are fertile when the two are crossed, the other

being slightly sterile, you will find that the latter will certainly

supplant the former in the struggle for existence; remembering that you

have shown that in such a cross the offspring would be more vigorous

than the pure breed, and therefore would certainly soon supplant them,

and as these would not be so well adapted to any special sphere of

existence as the pure species a and b, they would certainly in their

turn give way to a and b.

LETTER 210. TO A.R. WALLACE. February 27th [1868].

I shall be very glad to hear, at some future day, your criticisms on

the "causes of variability." Indeed, I feel sure that I am right about

sterility and Natural Selection. Two of my grown-up children who are

acute reasoners have two or three times at intervals tried to prove

me wrong; and when your letter came they had another try, but ended

by coming back to my side. I do not quite understand your case, and

we think that a word or two is misplaced. I wish some time you would

consider the case under the following point of view. If sterility is

caused or accumulated through Natural Selection, then, as every degree

exists up to absolute barrenness, Natural Selection must have the power

of increasing it. Now take two species A and B, and assume that they

are (by any means) half-sterile, i.e., produce half the full number of

offspring. Now try and make (by Natural Selection) A and B absolutely

sterile when crossed, and you will find how difficult it is. I

grant, indeed it is certain, that the degree of the sterility of the

individuals of A and B will vary; but any such extra-sterile individuals

of, we will say A, if they should hereafter breed with other individuals

of A, will bequeath no advantage to their progeny, by which these

families will tend to increase in number over other families of A, which

are not more sterile when crossed with B. But I do not know that I

have made this any clearer than in the chapter in my book. It is a most

difficult bit of reasoning, which I have gone over and over again on

paper with diagrams. (210/1. This letter appeared in "Life and Letters,"

III., page 80.)

LETTER 211. A.R. WALLACE TO CHARLES DARWIN. March 1st, 1868.

I beg to enclose what appears to me a demonstration on your own

principles, that Natural Selection could produce sterility of hybrids.

If it does not convince you, I shall be glad if you will point out

where the fallacy lies. I have taken the two cases of a slight sterility

overcoming perfect fertility, and of a perfect sterility overcoming a

partial fertility,--the beginning and end of the process. You admit that

variations in fertility and sterility occur, and I think you will also

admit that if I demonstrate that a considerable amount of sterility

would be advantageous to a variety, that is sufficient proof that the

slightest variation in that direction would be useful also, and would go

on accumulating.

1. Let there be a species which has varied into two forms, each adapted

to existing conditions (211/1. "Existing conditions," means of course

new conditions which have now come into existence. And the "two" being

both better adapted than the parent form, means that they are better

adapted each to a special environment in the same area--as one to damp,

another to dry places; one to woods, another to open grounds, etc.,

etc., as Darwin had already explained. A.R.W. (1899).) better than the

parent form, which they supplant.

2. If these two forms, which are supposed to co-exist in the same

district, do not intercross, Natural Selection will accumulate

favourable variations, till they become sufficiently well adapted to

their conditions of life and form two allied species.

3. But if these two forms freely intercross with each other and produce

hybrids which are also quite fertile inter se, then the formation of

the two distinct races or species will be retarded or perhaps entirely

prevented; for the offspring of the crossed unions will be more vigorous

owing to the cross, although less adapted to their conditions of

life than either of the pure breeds. (211/2. After "pure breeds," add

"because less specialised." A.R.W. (1899).)

4. Now let a partial sterility of some individuals of these two forms

arise when they intercross; and as this would probably be due to some

special conditions of life, we may fairly suppose it to arise in some

definite portion of the area occupied by the two forms.

5. The result is that in this area hybrids will not increase so rapidly

as before; and as by the terms of the problem the two pure forms are

better suited to the conditions of life than the hybrids, they will tend

to supplant the latter altogether whenever the struggle for existence

becomes severe.

6. We may fairly suppose, also, that as soon as any sterility appears

under natural conditions, it will be accompanied by some disinclination

to cross-unions; and this will further diminish the production of

hybrids.

7. In the other part of the area, however, where hybridism occurs

unchecked, hybrids of various degrees will soon far outnumber the parent

or pure form.

8. The first result, then, of a partial sterility of crosses appearing

in one part of the area occupied by the two forms, will be, that the

GREAT MAJORITY of the individuals will there consist of the pure forms

only, while in the rest of the area these will be in a minority,--which

is the same as saying, that the new sterile or physiological variety of

the two forms will be better suited to the conditions of existence than

the remaining portion which has not varied physiologically.

9. But when the struggle for existence becomes severe, that variety

which is best adapted to the conditions of existence always supplants

that which is imperfectly adapted; therefore by Natural Selection the

sterile varieties of the two forms will become established as the only

ones.

10. Now let a fresh series of variations in the amount of sterility and

in the disinclination to crossed unions occur,--also in certain parts

of the area: exactly the same result must recur, and the progeny of this

new physiological variety again in time occupy the whole area.

11. There is yet another consideration that supports this view. It seems

probable that the variations in amount of sterility would to some extent

concur with and perhaps depend upon the structural variations; so that

just in proportion as the two forms diverged and became better adapted

to the conditions of existence, their sterility would increase. If this

were the case, then Natural Selection would act with double strength,

and those varieties which were better adapted to survive both

structurally and physiologically, would certainly do so. (211/3. The

preceding eleven paragraphs are substantially but not verbally identical

with the statement of the argument in Mr. Wallace's "Darwinism," 1889.

Pages 179, 180, note 1.)

12. Let us now consider the more difficult case of two allied species

A, B, in the same area, half the individuals of each (As, Bs) being

absolutely sterile, the other half (Af, Bf) being partially fertile:

will As, Bs ultimately exterminate Af, Bf?

13. To avoid complication, it must be granted, that between As and Bs

no cross-unions take place, while between Af and Bf cross-unions are as

frequent as direct unions, though much less fertile. We must also leave

out of consideration crosses between As and Af, Bs and Bf, with their

various approaches to sterility, as I believe they will not affect the

final result, although they will greatly complicate the problem.

14. In the first generation there will result: 1st, The pure progeny of

As and Bs; 2nd, The pure progeny of Af and of Bf; and 3rd, The hybrid

progeny of Af, Bf.

15. Supposing that, in ordinary years, the increased constitutional

vigour of the hybrids exactly counterbalances their imperfect

adaptations to conditions, there will be in the second generation,

besides these three classes, hybrids of the second degree between the

first hybrids and Af and Bf respectively. In succeeding generations

there will be hybrids of all degrees, varying between the first hybrids

and the almost pure types of Af and Bf.

16. Now, if at first the number of individuals of As, Bs, Af and Bf

were equal, and year after year the total number continues stationary,

I think it can be proved that, while half will be the pure progeny of As

and Bs, the other half will become more and more hybridised, until the

whole will be hybrids of various degrees.

17. Now, this hybrid and somewhat intermediate race cannot be so well

adapted to the conditions of life as the two pure species, which have

been formed by the minute adaptation to conditions through Natural

Selection; therefore, in a severe struggle for existence, the hybrids

must succumb, especially as, by hypothesis, their fertility would not be

so great as that of the two pure species.

18. If we were to take into consideration the unions of As with Af and

Bs with Bf, the results would become very complicated, but it must still

lead to there being a number of pure forms entirely derived from As and

Bs, and of hybrid forms mainly derived from Af and Bf; and the result of

the struggle of these two sets of individuals cannot be doubtful.

19. If these arguments are sound, it follows that sterility may

be accumulated and increased, and finally made complete by Natural

Selection, whether the sterile varieties originate together in a

definite portion of the area occupied by the two species, or occur

scattered over the whole area. (211/4. The first part of this discussion

should be considered alone, as it is both more simple and more

important. I now believe that the utility, and therefore the cause of

sterility between species, is during the process of differentiation.

When species are fully formed, the occasional occurrence of hybrids

is of comparatively small importance, and can never be a danger to the

existence of the species. A.R.W. (1899).)

P.S.--In answer to the objection as to the unequal sterility of

reciprocal crosses ("Variation, etc." Volume II., page 186) I

reply that, as far as it went, the sterility of one cross would be

advantageous even if the other cross was fertile: and just as characters

now co-ordinated may have been separately accumulated by Natural

Selection, so the reciprocal crosses may have become sterile one at a

time.

LETTER 212. TO A.R. WALLACE. 4, Chester Place, March 17th, 1868.

(212/1. Mr. Darwin had already written a short note to Mr. Wallace

expressing a general dissent from his view.)

I do not feel that I shall grapple with the sterility argument till my

return home; I have tried once or twice, and it has made my stomach feel

as if it had been placed in a vice. Your paper has driven three of my

children half mad--one sat up till 12 o'clock over it. My second son,

the mathematician, thinks that you have omitted one almost inevitable

deduction which apparently would modify the result. He has written out

what he thinks, but I have not tried fully to understand him. I suppose

that you do not care enough about the subject to like to see what he has

written.

LETTER 212A. A.R. WALLACE TO CHARLES DARWIN. Hurstpierpoint, March, 24th

[1868].

I return your son's notes with my notes on them. Without going into any

details, is not this a strong general argument?

1. A species varies occasionally in two directions, but owing to their

free intercrossing the varieties never increase.

2. A change of conditions occurs which threatens the existence of the

species; but the two varieties are adapted to the changing conditions,

and if accumulated will form two new species adapted to the new

conditions.

3. Free crossing, however, renders this impossible, and so the species

is in danger of extinction.

4. If sterility would be induced, then the pure races would increase

more rapidly, and replace the old species.

5. It is admitted that partial sterility between varieties does

occasionally occur. It is admitted [that] the degree of this sterility

varies; is it not probable that Natural Selection can accumulate these

variations, and thus save the species? If Natural Selection can NOT do

this, how do species ever arise, except when a variety is isolated?

Closely allied species in distinct countries being sterile is no

difficulty; for either they diverged from a common ancestor in contact,

and Natural Selection increased the sterility, or they were isolated,

and have varied since: in which case they have been for ages influenced

by distinct conditions which may well produce sterility.

If the difficulty of grafting was as great as the difficulty of

crossing, and as regular, I admit it would be a most serious objection.

But it is not. I believe many distinct species can be grafted, while

others less distinct cannot. The regularity with which natural species

are sterile together, even when very much alike, I think is an argument

in favour of the sterility having been generally produced by Natural

Selection for the good of the species.

The other difficulty, of unequal sterility of reciprocal crosses, seems

none to me; for it is a step to more complete sterility, and as such

would be increased by selection.

LETTER 213. TO A.R. WALLACE. Down, April 6th [1868].

I have been considering the terrible problem. Let me first say that

no man could have more earnestly wished for the success of Natural

Selection in regard to sterility than I did; and when I considered a

general statement (as in your last note) I always felt sure it could be

worked out, but always failed in detail. The cause being, as I

believe, that Natural Selection cannot effect what is not good for the

individual, including in this term a social community. It would take a

volume to discuss all the points, and nothing is so humiliating to me

as to agree with a man like you (or Hooker) on the premises and disagree

about the result.

I agree with my son's argument and not with the rejoinder. The cause of

our difference, I think, is that I look at the number of offspring as an

important element (all circumstances remaining the same) in keeping up

the average number of individuals within any area. I do not believe that

the amount of food by any means is the sole determining cause of number.

Lessened fertility is equivalent to a new source of destruction. I

believe if in one district a species produced from any cause fewer

young, the deficiency would be supplied from surrounding districts. This

applies to your Paragraph 5. (213/1. See Letter 211.) If the species

produced fewer young from any cause in every district, it would become

extinct unless its fertility were augmented through Natural Selection

(see H. Spencer).

I demur to probability and almost to possibility of Paragraph 1., as

you start with two forms within the same area, which are not mutually

sterile, and which yet have supplanted the parent-form.

(Paragraph 6.) I know of no ghost of a fact supporting belief that

disinclination to cross accompanies sterility. It cannot hold with

plants, or the lower fixed aquatic animals. I saw clearly what an

immense aid this would be, but gave it up. Disinclination to cross seems

to have been independently acquired, probably by Natural Selection; and

I do not see why it would not have sufficed to have prevented incipient

species from blending to have simply increased sexual disinclination to

cross.

(Paragraph 11.) I demur to a certain extent to amount of sterility and

structural dissimilarity necessarily going together, except indirectly

and by no means strictly. Look at vars. of pigeons, fowls, and cabbages.

I overlooked the advantage of the half-sterility of reciprocal crosses;

yet, perhaps from novelty, I do not feel inclined to admit probability

of Natural Selection having done its work so queerly.

I will not discuss the second case of utter sterility, but your

assumptions in Paragraph 13 seem to me much too complicated. I cannot

believe so universal an attribute as utter sterility between remote

species was acquired in so complex a manner. I do not agree with

your rejoinder on grafting: I fully admit that it is not so closely

restricted as crossing, but this does not seem to me to weaken the case

as one of analogy. The incapacity of grafting is likewise an invariable

attribute of plants sufficiently remote from each other, and sometimes

of plants pretty closely allied.

The difficulty of increasing the sterility through Natural Selection of

two already sterile species seems to me best brought home by considering

an actual case. The cowslip and primrose are moderately sterile, yet

occasionally produce hybrids. Now these hybrids, two or three or a

dozen in a whole parish, occupy ground which might have been occupied

by either pure species, and no doubt the latter suffer to this small

extent. But can you conceive that any individual plants of the primrose

and cowslip which happened to be mutually rather more sterile (i.e.

which, when crossed, yielded a few less seed) than usual, would profit

to such a degree as to increase in number to the ultimate exclusion of

the present primrose and cowslip? I cannot.

My son, I am sorry to say, cannot see the full force of your rejoinder

in regard to second head of continually augmented sterility. You speak

in this rejoinder, and in Paragraph 5, of all the individuals becoming

in some slight degree sterile in certain districts: if you were to admit

that by continued exposure to these same conditions the sterility would

inevitably increase, there would be no need of Natural Selection. But

I suspect that the sterility is not caused so much by any particular

conditions as by long habituation to conditions of any kind. To speak

according to pangenesis, the gemmules of hybrids are not injured, for

hybrids propagate freely by buds; but their reproductive organs are

somehow affected, so that they cannot accumulate the proper gemmules,

in nearly the same manner as the reproductive organs of a pure species

become affected when exposed to unnatural conditions.

This is a very ill-expressed and ill-written letter. Do not answer it,

unless the spirit urges you. Life is too short for so long a discussion.

We shall, I greatly fear, never agree.

LETTER 214. A.R. WALLACE TO CHARLES DARWIN. Hurstpierpoint, [April?]

8th, 1868.

I am sorry you should have given yourself the trouble to answer my ideas

on sterility. If you are not convinced, I have little doubt but that I

am wrong; and, in fact, I was only half convinced by my own arguments,

and I now think there is about an even chance that Natural Selection may

or may not be able to accumulate sterility. If my first proposition is

modified to the existence of a species and a variety in the same area,

it will do just as well for my argument. Such certainly do exist. They

are fertile together, and yet each maintains itself tolerably distinct.

How can this be, if there is no disinclination to crossing?

My belief certainly is that number of offspring is not so important

an element in keeping up population of a species as supply of food and

other favourable conditions; because the numbers of a species constantly

vary greatly in different parts of its own area, whereas the average

number of offspring is not a very variable element.

However, I will say no more, but leave the problem as insoluble, only

fearing that it will become a formidable weapon in the hands of the

enemies of Natural Selection.

LETTER 215. TO J.D. HOOKER.

(215/1. The following extract from a letter to Sir Joseph Hooker (dated

April 3rd, 1868) refers to his Presidential Address for the approaching

meeting of the British Association at Norwich.

Some account of Sir Joseph's success is given in the "Life and Letters,"

III., page 100, also in Huxley's "Life," Volume I., page 297, where

Huxley writes to Darwin:--

"We had a capital meeting at Norwich, and dear old Hooker came out in

great force, as he always does in emergencies. The only fault was the

terrible 'Darwinismus' which spread over the section and crept out

when you least expected it, even in Fergusson's lecture on 'Buddhist

Temples.' You will have the rare happiness to see your ideas triumphant

during your lifetime.

"P.S.--I am going into opposition; I can't stand it.")

Down, April 3rd [1868].

I have been thinking over your Presidential Address; I declare I made

myself quite uncomfortable by fancying I had to do it, and feeling

myself utterly dumbfounded.

But I do not believe that you will find it so difficult. When you come

to Down I shall be very curious to hear what your ideas are on the

subject.

Could you make anything out of a history of the great steps in the

progress of Botany, as representing the whole of Natural History? Heaven

protect you! I suppose there are men to whom such a job would not be

so awful as it appears to me...If you had time, you ought to read an

article by W. Bagehot in the April number of the "Fortnightly" (215/2.

"Physic and Politics," "Fortnightly Review," Volume III., page 452,

1868.), applying Natural Selection to early or prehistoric politics,

and, indeed, to late politics,--this you know is your view.

LETTER 216. A.R. WALLACE TO CHARLES DARWIN. 9, St. Mark's Crescent,

N.W., August 16th [1868].

I ought to have written before to thank you for the copies of your

papers on Primula and on "Cross-unions of Dimorphic Plants, etc." The

latter is particularly interesting and the conclusion most important;

but I think it makes the difficulty of how these forms, with their

varying degrees of sterility, originated, greater than ever. If "natural

selection" could not accumulate varying degrees of sterility for the

plant's benefit, then how did sterility ever come to be associated with

one cross of a trimorphic plant rather than another? The difficulty

seems to be increased by the consideration that the advantage of a cross

with a distinct individual is gained just as well by illegitimate as

by legitimate unions. By what means, then, did illegitimate unions ever

become sterile? It would seem a far simpler way for each plant's pollen

to have acquired a prepotency on another individual's stigma over that

of the same individual, without the extraordinary complication of three

differences of structure and eighteen different unions with varying

degrees of sterility!

However, the fact remains an excellent answer to the statement that

sterility of hybrids proves the absolute distinctness of the parents.

I have been reading with great pleasure Mr. Bentham's last admirable

address (216/1. "Proc. Linn. Soc." 1867-8, page lvii.), in which he so

well replies to the gross misstatements of the "Athenaeum;" and also

says award in favour of pangenesis. I think we may now congratulate you

on having made a valuable convert, whose opinions on the subject, coming

so late and being evidently so well considered, will have much weight.

I am going to Norwich on Tuesday to hear Dr. Hooker, who I hope will

boldly promulgate "Darwinism" in his address. (216/2. Sir Joseph

Hooker's Presidential Address at the British Association Meeting.) Shall

we have the pleasure of seeing you there?

I am engaged in negociations about my book.

Hoping you are well and getting on with your next volumes.

(216/3. We are permitted by Mr. Wallace to append the following note

as to his more recent views on the question of Natural Selection and

sterility:--

"When writing my "Darwinism," and coming again to the consideration

of this problem of the effect of Natural Selection in accumulating

variations in the amount of sterility between varieties or incipient

species twenty years later, I became more convinced, than I was when

discussing with Darwin, of the substantial accuracy of my argument.

Recently a correspondent who is both a naturalist and a mathematician

has pointed out to me a slight error in my calculation at page 183

(which does not, however, materially affect the result), disproving the

'physiological selection' of the late Dr. Romanes, but he can see no

fallacy in my argument as to the power of Natural Selection to increase

sterility between incipient species, nor, so far as I am aware, has any

one shown such fallacy to exist.

"On the other points on which I differed from Mr. Darwin in the

foregoing discussion--the effect of high fertility on population of a

species, etc.--I still hold the views I then expressed, but it would be

out of place to attempt to justify them here."

A.R.W. (1899).)

LETTER 217. TO C. LYELL. Down, October 4th [1867].

With respect to the points in your note, I may sometimes have expressed

myself with ambiguity. At the end of Chapter XXIII., where I say that

marked races are not often (you omit "often") produced by changed

conditions (217/1. "Hence, although it must be admitted that new

conditions of life do sometimes definitely affect organic beings, it

may be doubted whether well-marked races have often been produced by the

direct action of changed conditions without the aid of selection either

by man or nature." ("Animals and Plants," Volume II., page 292, 1868.)),

I intended to refer to the direct action of such conditions in causing

variation, and not as leading to the preservation or destruction of

certain forms. There is as wide a difference in these two respects

as between voluntary selection by man and the causes which induce

variability. I have somewhere in my book referred to the close

connection between Natural Selection and the action of external

conditions in the sense which you specify in your note. And in this

sense all Natural Selection may be said to depend on changed conditions.

In the "Origin" I think I have underrated (and from the cause which

you mention) the effects of the direct action of external conditions in

producing varieties; but I hope in Chapter XXIII. I have struck as fair

a balance as our knowledge permits.

It is wonderful to me that you have patience to read my slips, and I

cannot but regret, as they are so imperfect; they must, I think, give

you a wrong impression, and had I sternly refused, you would perhaps

have thought better of my book. Every single slip is greatly altered,

and I hope improved.

With respect to the human ovule, I cannot find dimensions given, though

I have often seen the statement. My impression is that it would be just

or barely visible if placed on a clear piece of glass. Huxley could

answer your question at once.

I have not been well of late, and have made slow progress, but I think

my book will be finished by the middle of November.

LETTER 218. A.R. WALLACE TO CHARLES DARWIN. [End of February, 1868]

I am in the second volume of your book, and I have been astonished at

the immense number of interesting facts you have brought together. I

read the chapter on pangenesis first, for I could not wait. I can hardly

tell you how much I admire it. It is a positive comfort to me to have

any feasible explanation of a difficulty that has always been haunting

me, and I shall never be able to give it up till a better one supplies

its place,--and that I think hardly possible. You have now fairly beaten

Spencer on his own ground, for he really offered no solution of the

difficulties of the problem. The incomprehensible minuteness and vast

numbers of the physiological germs or atoms (which themselves must be

compounded of numbers of Spencer's physiological units) is the only

difficulty; but that is only on a par with the difficulties in all

conceptions of matter, space, motion, force, etc.

As I understood Spencer, his physiological units were identical

throughout each species, but slightly different in each different

species; but no attempt was made to show how the identical form of the

parent or ancestors came to be built up of such units.

LETTER 219. TO A.R. WALLACE. Down, February 27th [1868].

You cannot well imagine how much I have been pleased by what you say

about pangenesis. None of my friends will speak out, except to a certain

extent Sir H. Holland, who found it very tough reading, but admits that

some view "closely akin to it" will have to be admitted. Hooker, as far

as I understand him, which I hardly do at present, seems to think that

the hypothesis is little more than saying that organisms have such

and such potentialities. What you say exactly and fully expresses my

feelings--viz., that it is a relief to have some feasible explanation

of the various facts, which can be given up as soon as any better

hypothesis is found. It has certainly been an immense relief to my mind;

for I have been stumbling over the subject for years, dimly seeing that

some relation existed between the various classes of facts. I now hear

from H. Spencer that his views quoted in my footnote refer to something

quite distinct, as you seem to have perceived. (219/1. This letter is

published in "Life and Letters," III., page 79.)

LETTER 220. A.R. WALLACE TO CHARLES DARWIN. Hurstpierpoint, March 1st,

1868.

...Sir C. Lyell spoke to me as if he has greatly admired pangenesis. I

am very glad H. Spencer at once acknowledges that his view was something

quite distinct from yours. Although, as you know, I am a great admirer

of his, I feel how completely his view failed to go to the root of the

matter, as yours does. His explained nothing, though he was evidently

struggling hard to find an explanation. Yours, as far as I can see,

explains everything in growth and reproduction--though, of course, the

mystery of life and consciousness remains as great as ever.

Parts of the chapter on pangenesis I found hard reading, and have not

quite mastered yet, and there are also throughout the discussions in