CHAPTER 1.VI.--GEOGRAPHICAL DISTRIBUTION, 1843-1867.

LETTER 313. TO J.D. HOOKER. Down, Tuesday [December 12th, 1843].

I am very much obliged to you for your interesting letter. I have long

been very anxious, even for as short a sketch as you have kindly sent me

of the botanical geography of the southern hemisphere. I shall be most

curious to see your results in detail. From my entire ignorance of

Botany, I am sorry to say that I cannot answer any of the questions

which you ask me. I think I mention in my "Journal" that I found my old

friend the southern beech (I cannot say positively which species), on

the mountain-top, in southern parts of Chiloe and at level of sea in

lat. 45 deg, in Chonos Archipelago. Would not the southern end of Chiloe

make a good division for you? I presume, from the collection of Brydges

and Anderson, Chiloe is pretty well-known, and southward begins a terra

incognita. I collected a few plants amongst the Chonos Islands. The

beech being found here and peat being found here, and general appearance

of landscape, connects the Chonos Islands and T. del Fuego. I saw the

Alerce (313/1. "Alerse" is the local name of a South American timber,

described in Capt. King's "Voyages of the 'Adventure' and 'Beagle,'"

page 281, and rather doubtfully identified with Thuja tetragona, Hook.

("Flora Antarctica," page 350.)) on mountains of Chiloe (on the mainland

it grows to an enormous size, and I always believed Alerce and Araucaria

imbricata to be identical), but I am ashamed to say I absolutely forget

all about its appearance. I saw some Juniper-like bush in T. del Fuego,

but can tell you no more about it, as I presume that you have seen

Capt. King's collection in Mr. Brown's possession, provisionally for the

British Museum. I fear you will be much disappointed in my few plants:

an ignorant person cannot collect; and I, moreover, lost one, the

first, and best set of the Alpine plants. On the other hand, I hope the

Galapagos plants (313/2. See "Life and Letters," II., pages 20, 21,

for Sir J.D. Hooker's notes on the beginning of his friendship with Mr.

Darwin, and for the latter's letter on the Galapagos plants being placed

in Hooker's hands.) (judging from Henslow's remarks) will turn out more

interesting than you expect. Pray be careful to observe, if I ever mark

the individual islands of the Galapagos Islands, for the reasons you

will see in my "Journal." Menzies and Cumming were there, and there are

some plants (I think Mr. Bentham told me) at the Horticultural Society

and at the British Museum. I believe I collected no plants at Ascension,

thinking it well-known.

Is not the similarity of plants of Kerguelen Land and southern S.

America very curious? Is there any instance in the northern hemisphere

of plants being similar at such great distances? With thanks for your

letter and for your having undertaken my small collection of plants,

Believe me, my dear Sir, Yours very truly, C. DARWIN.

Do remember my prayer, and write as well for botanical ignoramuses

as for great botanists. There is a paper of Carmichael (313/3.

"Some Account of the Island of Tristan da Cunha and of its Natural

Productions."--"Linn. Soc. Trans." XII., 1818, page 483.) on Tristan

d'Acunha, which from the want of general remarks and comparison, I found

[torn out] to me a dead letter.--I presume you will include this island

in your views of the southern hemisphere.

P.S.--I have been looking at my poor miserable attempt at

botanical-landscape-remarks, and I see that I state that the species of

beech which is least common in T. del Fuego is common in the forest of

Central Chiloe. But I will enclose for you this one page of my rough

journal.

LETTER 314. TO J.D. HOOKER. Down, March 31st (1844).

I have been a shameful time in returning your documents, but I have been

very busy scientifically, and unscientifically in planting. I have been

exceedingly interested in the details about the Galapagos Islands.

I need not say that I collected blindly, and did not attempt to make

complete series, but just took everything in flower blindly. The flora

of the summits and bases of the islands appear wholly different; it may

aid you in observing whether the different islands have representative

species filling the same places in the economy of nature, to know that I

collected plants from the lower and dry region in all the islands, i.e.,

in the Chatham, Charles, James, and Albemarle (the least on the latter);

and that I was able to ascend into the high and damp region only in

James and Charles Islands; and in the former I think I got every plant

then in flower. Please bear this in mind in comparing the representative

species. (You know that Henslow has described a new Opuntia from the

Galapagos.) Your observations on the distribution of large mundane

genera have interested me much; but that was not the precise point which

I was curious to ascertain; it has no necessary relation to size of

genus (though perhaps your statements will show that it has). It was

merely this: suppose a genus with ten or more species, inhabiting the

ten main botanical regions, should you expect that all or most of these

ten species would have wide ranges (i.e. were found in most parts) in

their respective countries? (314/1. This point is discussed in a letter

in "Life and Letters," Volume II., page 25, but not, we think in the

"Origin"; for letters on large genera containing many varieties see

"Life and Letters," Volume II., pages 102-7, also in the "Origin,"

Edition I., page 53, Edition VI., page 44. In a letter of April 5th,

1844, Sir J.D. Hooker gave his opinion: "On the whole I believe that

many individual representative species of large genera have wide ranges,

but I do not consider the fact as one of great value, because the

proportion of such species having a wide range is not large compared

with other representative species of the same genus whose limits are

confined."

It may be noted that in large genera the species often have small ranges

("Origin," Edition VI., page 45), and large genera are more commonly

wide-ranging than the reverse.) To give an example, the genus Felis

is found in every country except Australia, and the individual species

generally range over thousands of miles in their respective countries;

on the other hand, no genus of monkey ranges over so large a part of the

world, and the individual species in their respective countries seldom

range over wide spaces. I suspect (but am not sure) that in the genus

Mus (the most mundane genus of all mammifers) the individual species

have not wide ranges, which is opposed to my query.

I fancy, from a paper by Don, that some genera of grasses (i.e. Juncus

or Juncaceae) are widely diffused over the world, and certainly many of

their species have very wide ranges--in short, it seems that my question

is whether there is any relation between the ranges of genera and of

individual species, without any relation to the size of the genera. It

is evident a genus might be widely diffused in two ways: 1st, by many

different species, each with restricted ranges; and 2nd, by many or

few species with wide ranges. Any light which you could throw on this I

should be very much obliged for. Thank you most kindly, also, for your

offer in a former letter to consider any other points; and at some

future day I shall be most grateful for a little assistance, but I will

not be unmerciful.

Swainson has remarked (and Westwood contradicted) that typical genera

have wide ranges: Waterhouse (without knowing these previous

remarkers) made to me the same observation: I feel a laudable doubt and

disinclination to believe any statement of Swainson; but now Waterhouse

remarks it, I am curious on the point. There is, however, so much vague

in the meaning of "typical forms," and no little ambiguity in the mere

assertion of "wide ranges" (for zoologists seldom go into strict and

disagreeable arithmetic, like you botanists so wisely do) that I feel

very doubtful, though some considerations tempt me to believe in this

remark. Here again, if you can throw any light, I shall be much obliged.

After your kind remarks I will not apologise for boring you with my

vague queries and remarks.

LETTER 315. TO J.D. HOOKER. Down, December 25th [1844]. Happy Christmas

to you.

(315/1. The following letter refers to notes by Sir J.D. Hooker which we

have not seen. Though we are therefore unable to make clear many points

referred to, the letter seems to us on the whole so interesting that it

is printed with the omission of only one unimportant sentence.

The subjects dealt with in the letter are those which were occupying

Hooker's attention in relation to his "Flora Antarctica" (1844).)

I must thank you once again for all your documents, which have

interested me very greatly and surprised me. I found it very difficult

to charge my head with all your tabulated results, but this I perfectly

well know is in main part due to that head not being a botanical one,

aided by the tables being in MS.; I think, however, to an ignoramus,

they might be made clearer; but pray mind, that this is very different

from saying that I think botanists ought to arrange their highest

results for non-botanists to understand easily. I will tell you how,

for my individual self, I should like to see the results worked out, and

then you can judge, whether this be advisable for the botanical world.

Looking at the globe, the Auckland and Campbell I., New Zealand, and

Van Diemen's Land so evidently are geographically related, that I should

wish, before any comparison was made with far more distant countries,

to understand their floras, in relation to each other; and the southern

ones to the northern temperate hemisphere, which I presume is to every

one an almost involuntary standard of comparison. To understand the

relation of the floras of these islands, I should like to see the group

divided into a northern and southern half, and to know how many species

exist in the latter--

1. Belonging to genera confined to Australia, Van Diemen's Land and

north New Zealand.

2. Belonging to genera found only on the mountains of Australia, Van

Diemen's Land, and north New Zealand.

3. Belonging to genera of distribution in many parts of the world (i.e.,

which tell no particular story).

4. Belonging to genera found in the northern hemisphere and not in the

tropics; or only on mountains in the tropics.

I daresay all this (as far as present materials serve) could be

extracted from your tables, as they stand; but to any one not familiar

with the names of plants, this would be difficult. I felt particularly

the want of not knowing which of the genera are found in the lowland

tropics, in understanding the relation of the Antarctic with the Arctic

floras.

If the Fuegian flora was treated in the analogous way (and this would

incidentally show how far the Cordillera are a high-road of genera), I

should then be prepared far more easily and satisfactorily to understand

the relations of Fuegia with the Auckland Islands, and consequently with

the mountains of Van Diemen's Land. Moreover, the marvellous facts

of their intimate botanical relation (between Fuegia and the Auckland

Islands, etc.) would stand out more prominently, after the Auckland

Islands had been first treated of under the purely geographical relation

of position. A triple division such as yours would lead me to suppose

that the three places were somewhat equally distant, and not so

greatly different in size: the relation of Van Diemen's Land seems so

comparatively small, and that relation being in its alpine plants, makes

me feel that it ought only to be treated of as a subdivision of the

large group, including Auckland, Campbell, New Zealand...

I think a list of the genera, common to Fuegia on the one hand and on

the other to Campbell, etc., and to the mountains of Van Diemen's Land

or New Zealand (but not found in the lowland temperate, and southern

tropical parts of South America and Australia, or New Zealand), would

prominently bring out, at the same time, the relation between these

Antarctic points one with another, and with the northern or Arctic

regions.

In Article III. is it meant to be expressed, or might it not be

understood by this article, that the similarity of the distant points

in the Antarctic regions was as close as between distant points in

the Arctic regions? I gather this is not so. You speak of the southern

points of America and Australia, etc., being "materially approximated,"

and this closer proximity being correlative with a greater similarity of

their plants: I find on the globe, that Van Diemen's Land and Fuegia are

only about one-fifth nearer than the whole distance between Port Jackson

and Concepcion in Chile; and again, that Campbell Island and Fuegia

are only one-fifth nearer than the east point of North New Zealand and

Concepcion. Now do you think in such immense distances, both over open

oceans, that one-fifth less distance, say 4,000 miles instead of 5,000,

can explain or throw much light on a material difference in the degree

of similarity in the floras of the two regions?

I trust you will work out the New Zealand flora, as you have commenced

at end of letter: is it not quite an original plan? and is it not very

surprising that New Zealand, so much nearer to Australia than South

America, should have an intermediate flora? I had fancied that nearly

all the species there were peculiar to it. I cannot but think you make

one gratuitous difficulty in ascertaining whether New Zealand ought to

be classed by itself, or with Australia or South America--namely, when

you seem (bottom of page 7 of your letter) to say that genera in

common indicate only that the external circumstances for their life are

suitable and similar. (315/2. On December 30th, 1844, Sir J.D. Hooker

replied, "Nothing was further from my intention than to have written

anything which would lead one to suppose that genera common to two

places indicate a similarity in the external circumstances under which

they are developed, though I see I have given you excellent grounds for

supposing that such were my opinions.") Surely, cannot an overwhelming

mass of facts be brought against such a proposition? Distant parts of

Australia possess quite distinct species of marsupials, but surely this

fact of their having the same marsupial genera is the strongest tie

and plainest mark of an original (so-called) creative affinity over

the whole of Australia; no one, now, will (or ought) to say that the

different parts of Australia have something in their external conditions

in common, causing them to be pre-eminently suitable to marsupials; and

so on in a thousand instances. Though each species, and consequently

genus, must be adapted to its country, surely adaptation is manifestly

not the governing law in geographical distribution. Is this not so?

and if I understand you rightly, you lessen your own means of

comparison--attributing the presence of the same genera to similarity of

conditions.

You will groan over my very full compliance with your request to write

all I could on your tables, and I have done it with a vengeance: I can

hardly say how valuable I must think your results will be, when worked

out, as far as the present knowledge and collections serve.

Now for some miscellaneous remarks on your letter: thanks for the offer

to let me see specimens of boulders from Cockburn Island; but I care

only for boulders, as an indication of former climate: perhaps Ross will

give some information...

Watson's paper on the Azores (315/3. H.C. Watson, "London Journal of

Botany," 1843-44.) has surprised me much; do you not think it odd, the

fewness of peculiar species, and their rarity on the alpine heights? I

wish he had tabulated his results; could you not suggest to him to draw

up a paper of such results, comparing these Islands with Madeira? surely

does not Madeira abound with peculiar forms?

A discussion on the relations of the floras, especially the alpine ones,

of Azores, Madeira, and Canary Islands, would be, I should think, of

general interest. How curious, the several doubtful species, which are

referred to by Watson, at the end of his paper; just as happens with

birds at the Galapagos...Any time that you can put me in the way of

reading about alpine floras, I shall feel it as the greatest kindness. I

grieve there is no better authority for Bourbon, than that stupid Bory:

I presume his remark that plants, on isolated volcanic islands are

polymorphous (i.e., I suppose, variable?) is quite gratuitous. Farewell,

my dear Hooker. This letter is infamously unclear, and I fear can be of

no use, except giving you the impression of a botanical ignoramus.

LETTER 316. TO J.D. HOOKER. Down, March 19th [1845].

...I was very glad to hear Humboldt's views on migrations and double

creations. It is very presumptuous, but I feel sure that though one

cannot prove extensive migration, the leading considerations, proper to

the subject, are omitted, and I will venture to say even by Humboldt.

I should like some time to put the case, like a lawyer, for your

consideration, in the point of view under which, I think, it ought to be

viewed. The conclusion which I come to is, that we cannot pretend,

with our present knowledge, to put any limit to the possible, and even

probable, migration of plants. If you can show that many of the Fuegian

plants, common to Europe, are found in intermediate points, it will be a

grand argument in favour of the actuality of migration; but not finding

them will not, in my eyes, much diminish the probability of their having

thus migrated. My pen always runs away, in writing to you; and a most

unsteady, vilely bad pace it goes. What would I not give to write simple

English, without having to rewrite and rewrite every sentence.

LETTER 317. TO J.D. HOOKER. Friday [June 29th, 1845].

I have been an ungrateful dog for not having answered your letter

sooner, but I have been so hard at work correcting proofs (317/1. The

second edition of the "Journal."), together with some unwellness, that

I have not had one quarter of an hour to spare. I finally corrected the

first third of the old volume, which will appear on July 1st. I hope and

think I have somewhat improved it. Very many thanks for your remarks;

some of them came too late to make me put some of my remarks more

cautiously. I feel, however, still inclined to abide by my evaporation

notion to account for the clouds of steam, which rise from the wooded

valleys after rain. Again, I am so obstinate that I should require very

good evidence to make me believe that there are two species of Polyborus

(317/2. Polyborus Novae Zelandiae, a carrion hawk mentioned as very

common in the Falklands.) in the Falkland Islands. Do the Gauchos there

admit it? Much as I talked to them, they never alluded to such a fact.

In the Zoology I have discussed the sexual and immature plumage, which

differ much.

I return the enclosed agreeable letter with many thanks. I am extremely

glad of the plants collected at St. Paul's, and shall be particularly

curious whenever they arrive to hear what they are. I dined the other

day at Sir J. Lubbock's, and met R. Brown, and we had much laudatory

talk about you. He spoke very nicely about your motives in now going

to Edinburgh. He did not seem to know, and was much surprised at what I

stated (I believe correctly) on the close relation between the Kerguelen

and T. del Fuego floras. Forbes is doing apparently very good work about

the introduction and distribution of plants. He has forestalled me in

what I had hoped would have been an interesting discussion--viz., on the

relation between the present alpine and Arctic floras, with connection

to the last change of climate from Arctic to temperate, when the then

Arctic lowland plants must have been driven up the mountains. (317/3.

Forbes' Essay "On the Connection between the Distribution of the

Existing Fauna and Flora of the British Isles and the Geological Changes

which have affected their Area," was published in 1846. See note, Letter

20.)

I am much pleased to hear of the pleasant reception you received at

Edinburgh. (317/4. Sir J.D. Hooker was a candidate for the Chair of

Botany at Edinburgh. See "Life and Letters," I., pages 335, 342.) I

hope your impressions will continue agreeable; my associations with auld

Reekie are very friendly. Do you ever see Dr. Coldstream? If you do,

would you give him my kind remembrances? You ask about amber. I believe

all the species are extinct (i.e. without the amber has been doctored),

and certainly the greater number are. (317/5. For an account of plants

in amber see Goeppert and Berendt, "Der Bernstein und die in ihm

befindlichen Pflanzenreste der Vorwelt," Berlin, 1845; Goeppert,

"Coniferen des Bernstein," Danzig, 1883; Conwentz, "Monographie der

Baltischen Bernsteinbaume," Danzig, 1890.)

If you have any other corrections ready, will you send them soon, for I

shall go to press with second Part in less than a week. I have been

so busy that I have not yet begun d'Urville, and have read only first

chapter of Canary Islands! I am most particularly obliged to you for

having lent me the latter, for I know not where else I could have ever

borrowed it. There is the "Kosmos" to read, and Lyell's "Travels in

North America." It is awful to think of how much there is to read. What

makes H. Watson a renegade? I had a talk with Captain Beaufort the other

day, and he charged me to keep a book and enter anything which occurred

to me, which deserved examination or collection in any part of the

world, and he would sooner or later get it in the instructions to some

ship. If anything occurs to you let me hear, for in the course of a

month or two I must write out something. I mean to urge collections of

all kinds on any isolated islands. I suspect that there are several in

the northern half of the Pacific, which have never been visited by a

collector. This is a dull, untidy letter. Farewell.

As you care so much for insular floras, are you aware that I collected

all in flower on the Abrolhos Islands? but they are very near the coast

of Brazil. Nevertheless, I think they ought to be just looked at, under

a geographical point of view.

LETTER 318. TO J.D. HOOKER. Down, November [1845].

I have just got as far as Lycopodium in your Flora, and, in truth,

cannot say enough how much I have been interested in all your scattered

remarks. I am delighted to have in print many of the statements which

you made in your letters to me, when we were discussing some of the

geographical points. I can never cease marvelling at the similarity of

the Antarctic floras: it is wonderful. I hope you will tabulate all

your results, and put prominently what you allude to (and what is

pre-eminently wanted by non-botanists like myself), which of the genera

are, and which not, found in the lowland or in the highland Tropics, as

far as known. Out of the very many new observations to me, nothing

has surprised me more than the absence of Alpine floras in the S[outh]

Islands. (318/1. See "Flora Antarctica," I., page 79, where the author

says that "in the South...on ascending the mountains, few or no new

forms occur." With regard to the Sandwich Islands, Sir Joseph wrote

(page 75) that "though the volcanic islands of the Sandwich group

attain a greater elevation than this [10,000 feet], there is no such

development of new species at the upper level." More recent statements

to the same effect occur in Grisebach, "Vegetation der Erde," Volume

II., page 530. See also Wallace, "Island Life," page 307.) It strikes me

as most inexplicable. Do you feel sure about the similar absence in the

Sandwich group? Is it not opposed quite to the case of Teneriffe and

Madeira, and Mediterranean Islands? I had fancied that T. del Fuego had

possessed a large alpine flora! I should much like to know whether

the climate of north New Zealand is much more insular than Tasmania. I

should doubt it from general appearance of places, and yet I presume the

flora of the former is far more scanty than of Tasmania. Do tell me what

you think on this point. I have also been particularly interested by

all your remarks on variation, affinities, etc.: in short, your book has

been to me a most valuable one, and I must have purchased it had you not

most kindly given it, and so rendered it even far more valuable to me.

When you compare a species to another, you sometimes do not mention

the station of the latter (it being, I presume, well-known), but

to non-botanists such words of explanation would add greatly to

the interest--not that non-botanists have any claim at all for such

explanations in professedly botanical works. There is one expression

which you botanists often use (though, I think, not you individually

often), which puts me in a passion--viz., calling polleniferous flowers

"sterile," as non-seed-bearing. (318/2. See Letter 16.) Are the plates

from your own drawings? They strike me as excellent. So now you have had

my presumptuous commendations on your great work.

LETTER 319. TO J.D. HOOKER. Down, Friday [1845-6].

It is quite curious how our opinions agree about Forbes' views. (319/1.

See Letter 20.) I was very glad to have your last letter, which was even

more valuable to me than most of yours are, and that is saying, I assure

you, a great deal. I had written to Forbes to object about the Azores

(319/2. Edward Forbes supposed that the Azores, the Madeiras, and

Canaries "are the last remaining fragments" of a continent which

once connected them with Western Europe and Northern Spain. Lyell's

"Principles," Edition XI., Volume II., page 410. See Forbes, op. cit.)

on the same grounds as you had, and he made some answer, which partially

satisfied me, but really I am so stupid I cannot remember it. He

insisted strongly on the fewness of the species absolutely peculiar to

the Azores--most of the non-European species being common to Madeira. I

had thought that a good sprinkling were absolutely peculiar. Till I saw

him last Wednesday I thought he had not a leg to stand on in his geology

about his post-Miocene land; and his reasons, upon reflection, seem

rather weak: the main one is that there are no deposits (more recent

than the Miocene age) on the Miocene strata of Malta, etc., but I feel

pretty sure that this cannot be trusted as evidence that Malta must have

been above water during all the post-Miocene period. He had one other

reason, to my mind still less trustworthy. I had also written to Forbes,

before your letter, objecting to the Sargassum (319/3. Edward Forbes

supposed that the Sargassum or Gulf-weed represents the littoral

sea-weeds of a now submerged continent. "Mem. Geol. Survey Great

Britain," Volume I., 1846, page 349. See Lyell's "Principles," II., page

396, Edition XI.), but apparently on wrong grounds, for I could see no

reason, on the common view of absolute creations, why one Fucus should

not have been created for the ocean, as well as several Confervae for

the same end. It is really a pity that Forbes is quite so speculative:

he will injure his reputation, anyhow, on the Continent; and thus will

do less good. I find this is the opinion of Falconer, who was with us

on Sunday, and was extremely agreeable. It is wonderful how much

heterogeneous information he has about all sorts of things. I the more

regret Forbes cannot more satisfactorily prove his views, as I heartily

wish they were established, and to a limited extent I fully believe they

are true; but his boldness is astounding. Do I understand your letter

right, that West Africa (319/4. This is of course a misunderstanding.)

and Java belong to the same botanical region--i.e., that they have many

non-littoral species in common? If so, it is a sickening fact: think of

the distance with the Indian Ocean interposed! Do some time answer me

this. With respect to polymorphism, which you have been so very kind as

to give me so much information on, I am quite convinced it must be given

up in the sense you have discussed it in; but from such cases as the

Galapagos birds and from hypothetical notions on variation, I should be

very glad to know whether it must be given up in a slightly different

point of view; that is, whether the peculiar insular species are

generally well and strongly distinguishable from the species on the

nearest continent (when there is a continent near); the Galapagos,

Canary Islands, and Madeira ought to answer this. I should have

hypothetically expected that a good many species would have been

fine ones, like some of the Galapagos birds, and still more so on the

different islands of such groups.

I am going to ask you some questions, but I should really sometimes

almost be glad if you did not answer me for a long time, or not at all,

for in honest truth I am often ashamed at, and marvel at, your kindness

in writing such long letters to me. So I beg you to mind, never to

write to me when it bores you. Do you know "Elements de Teratologie (on

monsters, I believe) Vegetale," par A. Moquin Tandon"? (319/5.

Paris, 1841.) Is it a good book, and will it treat on hereditary

malconformations or varieties? I have almost finished the tremendous

task of 850 pages of A. St. Hilaire's Lectures (319/6. "Lecons de

Botanique," 1841.), which you set me, and very glad I am that you told

me to read it, for I have been much interested with parts. Certain

expressions which run through the whole work put me in a passion: thus I

take, at hazard, "la plante n'etait pas tout a fait ASSEZ AFFAIBLIE

pour produire de veritables carpelles." Every organ or part concerned in

reproduction--that highest end of all lower organisms--is, according to

this man, produced by a lesser or greater degree of "affaiblissement";

and if that is not an AFFAIBLISSEMENT of language, I don't know what is.

I have used an expression here, which leads me to ask another question:

on what sort of grounds do botanists make one family of plants higher

than another? I can see that the simplest cryptogamic are lowest, and I

suppose, from their relations, the monocotyledonous come next; but how

in the different families of the dicotyledons? The point seems to me

equally obscure in many races of animals, and I know not how to tell

whether a bee or cicindela is highest. (319/7. On use of terms "high"

and "low" see Letters 36 and 70.) I see Aug. Hilaire uses a multiplicity

of parts--several circles of stamens, etc.--as evidence of the highness

of the Ranunculaceae; now Owen has truly, as I believe, used the same

argument to show the lowness of some animals, and has established the

proposition, that the fewer the number of any organ, as legs or wings or

teeth, by which the same end is gained, the higher the animal. One other

question. Hilaire says (page 572) that "chez une foule de plantes

c'est dans le bouton," that impregnation takes place. He instances only

Goodenia (319/8. For letters on this point, see Index s.v. Goodenia.),

and Falconer cannot recollect any cases. Do you know any of this "foule"

of plants? From reasons, little better than hypothetical, I greatly

misdoubt the accuracy of this, presumptuous as it is; that plants shed

their pollen in the bud is, of course, quite a different story. Can you

illuminate me? Henslow will send the Galapagos scraps to you. I direct

this to Kew, as I suppose, after your sister's marriage (on which I beg

to send you my congratulations), you will return home.

There are great fears that Falconer will have to go out to India--this

will be a grievous loss to Palaeontology.

LETTER 320. TO J.D. HOOKER. Down, April 10th [1846].

I was much pleased to see and sign your certificate for the Geolog[ical

Society]; we shall thus occasionally, I hope, meet. (320/1. Sir Joseph

was elected a Fellow of the Geological Society in 1846.)

I have been an ungrateful dog not to have thanked you before this for

the cake and books. The children and their betters pronounced the former

excellent, and Annie wanted to know whether it was the gentleman "what

played with us so." I wish we were at a more reasonable distance,

that Emma and myself could have called on Lady Hooker with our

congratulations on this occasion. It was very good of you to put in

both numbers of the "Hort. Journal." I think Dean Herbert's article well

worth reading. I have been so extravagant as to order M[oquin] Tandon

(320/2. Probably "Elements de Teratologie Vegetale": Paris, 1841.),

for though I have not found, as yet, anything particularly novel or

striking, yet I found that I wished to score a good many passages so as

to re-read them at some future time, and hence have ordered the book.

Consequently I hope soon to send back your books. I have sent off the

Ascension plants through Bunsen to Ehrenberg.

There was much in your last long letter which interested me much; and I

am particularly glad that you are going to attend to polymorphism in

our last and incorrect sense in your works; I see that it must be most

difficult to take any sort of constant limit for the amount of possible

variation. How heartily I do wish that all your works were out and

complete; so that I could quietly think over them. I fear the Pacific

Islands must be far distant in futurity. I fear, indeed, that Forbes is

going rather too quickly ahead; but we shall soon see all his grounds,

as I hear he is now correcting the press on this subject; he has plenty

of people who attack him; I see Falconer never loses a chance, and it

is wonderful how well Forbes stands it. What a very striking fact is the

botanical relation between Africa and Java; as you now state it, I

am pleased rather than disgusted, for it accords capitally with

the distribution of the mammifers (320/3. See Wallace, "Geogr.

Distribution," Volume I., page 263, on the "special Oriental or even

Malayan element" in the West African mammals and birds.): only that I

judge from your letters that the Cape differs even more markedly than I

had thought, from the rest of Africa, and much more than the mammifers

do. I am surprised to find how well mammifers and plants seem to accord

in their general distribution. With respect to my strong objection to

Aug. St. Hilaire's language on AFFAIBLISSEMENT (320/4. This refers to

his "Lecons de Botanique (Morphologie Vegetale)," 1841. Saint-Hilaire

often explains morphological differences as due to differences in

vigour. See Letter 319.), it is perhaps hardly rational, and yet he

confesses that some of the most vigorous plants in nature have some of

their organs struck with this weakness--he does not pretend, of course,

that they were ever otherwise in former generations--or that a more

vigorously growing plant produces organs less weakened, and thus fails

in producing its typical structure. In a plant in a state of nature,

does cutting off the sap tend to produce flower-buds? I know it does in

trees in orchards. Owen has been doing some grand work in the morphology

of the vertebrata: your arm and hand are parts of your head, or rather

the processes (i.e. modified ribs) of the occipital vertebra! He gave me

a grand lecture on a cod's head. By the way, would it not strike you as

monstrous, if in speaking of the minute and lessening jaws, palpi, etc.,

of an insect or crustacean, any one were to say they were produced

by the affaiblissement of the less important but larger organs of

locomotion. I see from your letter (though I do not suppose it is worth

referring to the subject) that I could not have expressed what I meant

when I allowed you to infer that Owen's rule of single organs being of

a higher order than multiple organs applied only to locomotive, etc.; it

applies to every the most important organ. I do not doubt that he would

say the placentata having single wombs, whilst the marsupiata have

double ones, is an instance of this law. I believe, however, in most

instances where one organ, as a nervous centre or heart, takes the

places of several, it rises in complexity; but it strikes me as really

odd, seeing in this instance eminent botanists and zoologists starting

from reverse grounds. Pray kindly bear in mind about impregnation in

bud: I have never (for some years having been on the look-out) heard of

an instance: I have long wished to know how it was in Subularia, or some

such name, which grows on the bottom of Scotch lakes, and likewise in a

grassy plant, which lives in brackish water, I quite forget name, near

Thames; elder botanists doubted whether it was a Phanerogam. When we

meet I will tell you why I doubt this bud-impregnation.

We are at present in a state of utmost confusion, as we have pulled

all our offices down and are going to rebuild and alter them. I am

personally in a state of utmost confusion also, for my cruel wife has

persuaded me to leave off snuff for a month; and I am most lethargic,

stupid, and melancholy in consequence.

Farewell, my dear Hooker. Ever yours.

LETTER 321. TO J.D. HOOKER. Down, April 19th [1855].

Thank you for your list of R.S. candidates, which will be very useful to

me.

I have thought a good deal about my salting experiments (321/1. For

an account of Darwin's experiments on the effect of salt water on the

germination of seeds, see "Life and Letters," II., page 54. In April

he wrote to the "Gardeners' Chronicle" asking for information, and his

results were published in the same journal, May 26th and November 24th,

1855; also in the "Linn. Soc. Journal," 1857.), and really think they

are worth pursuing to a certain extent; but I hardly see the use

(at least, the use equivalent to the enormous labour) of trying the

experiment on the immense scale suggested by you. I should think a

few seeds of the leading orders, or a few seeds of each of the classes

mentioned by you, with albumen of different kinds would suffice to show

the possibility of considerable sea-transportal. To tell whether any

particular insular flora had thus been transported would require that

each species should be examined. Will you look through these printed

lists, and if you can, mark with red cross such as you would suggest? In

truth, I fear I impose far more on your great kindness, my dear Hooker,

than I have any claim; but you offered this, for I never thought of

asking you for more than a suggestion. I do not think I could manage

more than forty or fifty kinds at a time, for the water, I find, must

be renewed every other day, as it gets to smell horribly: and I do not

think your plan good of little packets of cambric, as this entangles

so much air. I shall keep the great receptacle with salt water with

the forty or fifty little bottles, partly open, immersed in it, in the

cellar for uniform temperature. I must plant out of doors, as I have no

greenhouse.

I told you I had inserted notice in the "Gardeners' Chronicle," and

to-day I have heard from Berkeley that he has already sent an assortment

of seeds to Margate for some friend to put in salt water; so I suppose

he thinks the experiment worth trying, as he has thus so very promptly

taken it into his own hands. (321/2. Rev. M.J. Berkeley published on the

subject in the "Gardeners' Chronicle," September 1st, 1855.)

Reading this over, it sounds as if I were offended!!! which I need not

say is not so. (321/3. Added afterwards between the lines.)

I may just mention that the seeds mentioned in my former note have all

germinated after fourteen days' immersion, except the cabbages all dead,

and the radishes have had their germination delayed and several I think

dead; cress still all most vigorous. French spinach, oats, barley,

canary-seed, borage, beet have germinated after seven days' immersion.

It is quite surprising that the radishes should have grown, for the salt

water was putrid to an extent which I could not have thought credible

had I not smelt it myself, as was the water with the cabbage-seed.

LETTER 322. TO J.D. HOOKER. Down, June 10th [1855].

If being thoroughly interested with your letters makes me worthy of

them, I am very worthy.

I have raised some seedling Sensitive Plants, but if you can READILY

spare me a moderately sized plant, I shall be glad of it.

You encourage me so, that I will slowly go on salting seeds. I have

not, I see, explained myself, to let you suppose that I objected to such

cases as the former union of England and the Continent; I look at this

case as proved by animals, etc., etc.; and, indeed, it would be an

astounding fact if the land had kept so steady as that they had not been

united, with Snowdon elevated 1,300 feet in recent times, etc., etc.

It is only against the former union with the oceanic volcanic islands

that I am vehement. (322/1. See "Life and Letters," Volume II., pages

72, 74, 80, 109.) What a perplexing case New Zealand does seem: is

not the absence of Leguminosae, etc., etc., FULLY as much opposed to

continental connexion as to any other theory? What a curious fact you

state about distribution and lowness going together.

The presence of a frog in New Zealand seems to me a strongish fact for

continental connexion, for I assume that sea water would kill spawn, but

I shall try. The spawn, I find, will live about ten days out of water,

but I do not think it could possibly stick to a bird.

What you say about no one realising creation strikes me as very true;

but I think and hope that there is nearly as much difference between

trying to find out whether species of a genus have had a common ancestor

and concerning oneself with the first origin of life, as between making

out the laws of chemical attraction and the first origin of matter.

I thought that Gray's letter had come open to you, and that you had read

it: you will see what I asked--viz., for habitats of the alpine plants,

but I presume there will be nothing new to you. Please return both. How

pleasantly Gray takes my request, and I think I shall have done a good

turn if I make him write a paper on geographical distribution of plants

of United States.

I have written him a very long letter, telling him some of the points

about which I should feel curious. But on my life it is sublimely

ridiculous, my making suggestions to such a man.

I cannot help thinking that what you say about low plants being widely

distributed and standing injurious conditions better than higher ones

(but is not this most difficult to show?) is equally favourable to

sea-transport, to continental connexions, and all other means. Pray

do not suppose that I fancy that if I could show that nearly all seeds

could stand an almost indefinite period of immersion in sea-water, that

I have done more than one EXTREMELY SMALL step in solving the problem of

distribution, for I can quite appreciate the importance of the fact you

point out; and then the directions of currents in past and present times

have to be considered!!

I shall be very curious to hear Berkeley's results in the salting line.

With respect to geological changes, I ought to be one of the last men

to undervalue them after my map of coral islands, and after what I have

seen of elevation on coast of America. Farewell. I hope my letters do

not bother you. Again, and for the last time, I say that I should be

extremely vexed if ever you write to me against the grain or when tired.

LETTER 323. TO J.S HENSLOW. Down, July 2nd [1855].

Very many thanks for all you have done, and so very kindly promise to do

for me.

Will you make a present to each of the little girls (if not too big

and grandiose) of six pence (for which I send stamps), who are going to

collect seeds for me: viz., Lychnis, white, red, and flesh-colour (if

such occur).

...Will you be so kind as to look at them before sent, just to see

positively that they are correct, for remember how ignorant botanically

I am.

Do you see the "Gardeners' Chronicle," and did you notice some little

experiments of mine on salting seeds? Celery and onion seed have come up

after eighty-five days' immersion in the salt water, which seems to

me surprising, and I think throws some light on the wide dispersion

of certain plants. Now, it has occurred to me that it would be an

interesting way of testing the probability of sea-transportal of seeds,

to make a list of all the European plants found in the Azores--a very

oceanic archipelago--collect the seeds, and try if they would stand a

pretty long immersion. Do you think the most able of your little girls

would like to collect for me a packet of seeds of such Azorean plants as

grow near Hitcham, I paying, say 3 pence for each packet: it would put a

few shillings into their pockets, and would be an enormous advantage

to me, for I grudge the time to collect the seeds, more especially as I

have to learn the plants! The experiment seems to me worth trying: what

do you think? Should you object offering for me this reward or payment

to your little girls? You would have to select the most conscientious

ones, that I might not get wrong seeds. I have just been comparing the

lists, and I suspect you would not have very many of the Azorean plants.

You have, however,

Ranunculus repens,

Ranunculus parviflorus,

Papaver rhoeas,?

Papaver dubium,?

Chelidonium majus,?

Fumaria officinalis.?

All these are Azorean plants.

With respect to cultivating plants, I mean to begin on very few, for

I may find it too troublesome. I have already had for some months

primroses and cowslips, strongly manured with guano, and with flowers

picked off, and one cowslip made to grow in shade; and next spring I

shall collect seed.

I think you have quite misunderstood me in regard to my object in

getting you to mark in accompanying list with (x) all the "close

species" (323/1. See Letter 279.) i.e., such as you do not think to

be varieties, but which nevertheless are very closely allied; it has

nothing whatever to do with their cultivation, but I cannot tell you

[my] object, as it might unconsciously influence you in marking them.

Will you draw your pencil right through all the names of those (few)

species, of which you may know nothing. Afterwards, when done, I will

tell you my object--not that it is worth telling, though I myself am

very curious on the subject. I know and can perceive that the definition

of "close species" is very vague, and therefore I should not care for

the list being marked by any one, except by such as yourself.

Forgive this long letter. I thank you heartily for all your assistance.

My dear old Master, Yours affectionately, C. Darwin.

Perhaps 3 pence would be hardly enough, and if the number of kinds does

not turn out very great it shall be 6 pence per packet.

LETTER 324. ASA GRAY TO CHARLES DARWIN.

(324/1. In reply to Darwin's letter, June 8th, 1855, given in "Life and

Letters," II., page 61.)

Harvard University, Cambridge, U.S., June 30th, 1855.

Your long letter of the 8th inst. is full of interest to me, and I shall

follow out your hints as far as I can. I rejoice in furnishing facts to

others to work up in their bearing on general questions, and feel it the

more my duty to do so inasmuch as from preoccupation of mind and

time and want of experience I am unable to contribute direct original

investigations of the sort to the advancement of science.

Your request at the close of your letter, which you have such needless

hesitation in making, is just the sort of one which it is easy for me to

reply to, as it lies directly in my way. It would probably pass out of

my mind, however, at the time you propose, so I will attend to it at

once, to fill up the intervals of time left me while attending to one or

two pupils. So I take some unbound sheets of a copy of the "Manual," and

mark off the "close species" by connecting them with a bracket.

Those thus connected, some of them, I should in revision unite under

one, many more Dr. Hooker would unite, and for the rest it would not

be extraordinary if, in any case, the discovery of intermediate forms

compelled their union.

As I have noted on the blank page of the sheets I send you (through Sir

William Hooker), I suppose that if we extended the area, say to that of

our flora of North America, we should find that the proportion of "close

species" to the whole flora increased considerably. But here I speak at

a venture. Some day I will test it for a few families.

If you take for comparison with what I send you, the "British Flora,"

or Koch's "Flora Germanica," or Godron's "Flora of France," and mark the

"close species" on the same principle, you will doubtless find a much

greater number. Of course you will not infer from this that the two

floras differ in this respect; since the difference is probably owing to

the facts that (1) there have not been so many observers here bent upon

detecting differences; and (2) our species, thanks mostly to Dr. Torrey

and myself, have been more thoroughly castigated. What stands for one

species in the "Manual" would figure in almost any European flora as

two, three, or more, in a very considerable number of cases.

In boldly reducing nominal species J. Hooker is doing a good work;

but his vocation--like that of any other reformer--exposes him to

temptations and dangers.

Because you have shown that a and b are so connected by intermediate

forms that we cannot do otherwise than regard them as variations of one

species, we may not conclude that c and d, differing much in the same

way and to the same degree, are of one species, before an equal amount

of evidence is actually obtained. That is, when two sets of individuals

exhibit any grave differences, the burden of proof of their common

origin lies with the person who takes that view; and each case must be

decided on its own evidence, and not on analogy, if our conclusions

in this way are to be of real value. Of course we must often jump at

conclusions from imperfect evidence. I should like to write an essay on

species some day; but before I should have time to do it, in my plodding

way, I hope you or Hooker will do it, and much better far. I am most

glad to be in conference with Hooker and yourself on these matters, and

I think we may, or rather you may, in a few years settle the question as

to whether Agassiz's or Hooker's views are correct; they are certainly

widely different.

Apropos to this, many thanks for the paper containing your experiments

on seeds exposed to sea water. Why has nobody thought of trying the

experiment before, instead of taking it for granted that salt water

kills seeds? I shall have it nearly all reprinted in "Silliman's

Journal" as a nut for Agassiz to crack.

LETTER 325. TO ASA GRAY. Down, May 2nd [1856?]

I have received your very kind note of April 8th. In truth it is

preposterous in me to give you hints; but it will give me real pleasure

to write to you just as I talk to Hooker, who says my questions

are sometimes suggestive owing to my comparing the ranges, etc., in

different kingdoms of Nature. I will make no further apologies about my

presumption; but will just tell you (though I am certain there will be

VERY little new in what I suggest and ask) the points on which I am very

anxious to hear about. I forget whether you include Arctic America, but

if so, for comparison with other parts of world, I would exclude the

Arctic and Alpine-Arctic, as belonging to a quite distinct category.

When excluding the naturalised, I think De Candolle must be right in

advising the exclusion (giving list) of plants exclusively found

in cultivated land, even when it is not known that they have been

introduced by man. I would give list of temperate plants (if any) found

in Eastern Asia, China, and Japan, and not elsewhere. Nothing would give

me a better idea of the flora of United States than the proportion of

its genera to all the genera which are confined to America; and the

proportion of genera confined to America and Eastern Asia with Japan;

the remaining genera would be common to America and Europe and the rest

of world; I presume it would be impossible to show any especial affinity

in genera, if ever so few, between America and Western Europe. America

might be related to Eastern Asia (always excluding Arctic forms) by a

genus having the same species confined to these two regions; or it might

be related by the genus having different species, the genus itself not

being found elsewhere. The relation of the genera (excluding identical

species) seems to me a most important element in geographical

distribution often ignored, and I presume of more difficult application

in plants than in animals, owing to the wider ranges of plants; but I

find in New Zealand (from Hooker) that the consideration of genera with

representative species tells the story of relationship even plainer than

the identity of the species with the different parts of the world. I

should like to see the genera of the United States, say 500 (excluding

Arctic and Alpine) divided into three classes, with the proportions

given thus:--

100/500 American genera;

200/500 Old World genera, but not having any identical species in

common;

200/500 Old World genera, but having some identical species in common;

Supposing that these 200 genera included 600 U.S. plants, then the 600

would be the denominator to the fraction of the species common to the

Old World. But I am running on at a foolish length.

There is an interesting discussion in De Candolle (about pages 503-514)

on the relation of the size of families to the average range of

the individual species; I cannot but think, from some facts which I

collected long before De Candolle appeared, that he is on wrong scent in

having taken families (owing to their including too great a diversity

in the constitution of the species), but that if he had taken genera, he

would have found that the individual species in large genera range over

a greater area than do the species in small genera: I think if you have

materials that this would be well worth working out, for it is a very

singular relation.

With respect to naturalised plants: are any social with you, which are

not so in their parent country? I am surprised that the importance of

this has not more struck De Candolle. Of these naturalised plants are

any or many more variable in your opinion than the average of your

United States plants? I am aware how very vague this must be; but

De Candolle has stated that the naturalised plants do not present

varieties; but being very variable and presenting distinct varieties

seems to me rather a different case: if you would kindly take the

trouble to answer this question I should be very much obliged, whether

or no you will enter on such points in your essay.

With respect to such plants, which have their southern limits within

your area, are the individuals ever or often stunted in their growth

or unhealthy? I have in vain endeavoured to find any botanist who has

observed this point; but I have seen some remarks by Barton on the

trees in United States. Trees seem in this respect to behave rather

differently from other plants.

It would be a very curious point, but I fear you would think it out of

your essay, to compare the list of European plants in Tierra del Fuego

(in Hooker) with those in North America; for, without multiple creation,

I think we must admit that all now in T. del Fuego must have travelled

through North America, and so far they do concern you.

The discussion on social plants (vague as the terms and facts are) in

De Candolle strikes me as the best which I have ever seen: two points

strike me as eminently remarkable in them; that they should ever be

social close to their extreme limits; and secondly, that species having

an extremely confined range, yet should be social where they do occur: I

should be infinitely obliged for any cases either by letter or publicly

on these heads, more especially in regard to a species remaining or

ceasing to be social on the confines of its range.

There is one other point on which I individually should be extremely

much obliged, if you could spare the time to think a little bit and

inform me: viz., whether there are any cases of the same species being

more variable in United States than in other countries in which it

is found, or in different parts of the United States? Wahlenberg says

generally that the same species in going south become more variable than

in extreme north. Even still more am I anxious to know whether any of

the genera, which have most of their species horribly variable (as

Rubus or Hieracium are) in Europe, or other parts of the world, are less

variable in the United States; or, the reverse case, whether you have

any odious genera with you which are less odious in other countries? Any

information on this head would be a real kindness to me.

I suppose your flora is too great; but a simple list in close columns in

small type of all the species, genera, and families, each consecutively

numbered, has always struck me as most useful; and Hooker regrets that

he did not give such list in introduction to New Zealand and other

Flora. I am sure I have given you a larger dose of questions than you

bargained for, and I have kept my word and treated you just as I do

Hooker. Nevertheless, if anything occurs to me during the next two

months, I will write freely, believing that you will forgive me and not

think me very presumptuous.

How well De Candolle shows the necessity of comparing nearly equal areas

for proportion of families!

I have re-read this letter, and it is really not worth sending, except

for my own sake. I see I forgot, in beginning, to state that it appeared

to me that the six heads of your Essay included almost every point which

could be desired, and therefore that I had little to say.

LETTER 326. TO J.D. HOOKER.

(326/1. On July 5th, 1856, Darwin wrote to Sir J.D. Hooker:--

"I am going mad and am in despair over your confounded Antarctic island

flora. Will you read over the Tristan list, and see if my remarks on it

are at all accurate. I cannot make out why you consider the vegetation

so Fuegian.")

Down, 8th [July, 1856].

I do hope that this note may arrive in time to save you trouble in one

respect. I am perfectly ashamed of myself, for I find in introduction to

Flora of Fuegia (326/2. "Flora Antarctica," page 216. "Though only 1,000

miles distant from the Cape of Good Hope, and 3,000 from the Strait of

Magalhaens, the botany of this island [Tristan d'Acunha] is far more

intimately allied to that of Fuegia than Africa." Hooker goes on to say

that only Phylica and Pelargonium are Cape forms, while seven species,

or one-quarter of the flora, "are either natives of Fuegia or typical

of South American botany, and the ferns and Lycopodia exhibit a still

stronger affinity.") a short discussion on Tristan plants, which though

scored [i.e. marked in pencil] I had quite forgotten at the time, and

had thought only of looking into introduction to New Zealand Flora. It

was very stupid of me. In my sketch I am forced to pick out the most

striking cases of species which favour the multiple creation doctrine,

without indeed great continental extensions are admitted. Of the many

wonderful cases in your books, the one which strikes me most is that

list of species, which you made for me, common to New Zealand and

America, and confined to southern hemisphere; and in this list those

common to Chile and New Zealand seem to me the most wondrous. I have

copied these out and enclosed them. Now I will promise to ask no more

questions, if you will tell me a little about these. What I want to know

is, whether any or many of them are mountain plants of Chile, so as

to bring them in some degree (like the Chonos plants) under the same

category with the Fuegian plants? I see that all the genera (Edwardsia

even having Sandwich Island and Indian species) are wide-ranging genera,

except Myosurus, which seems extra wonderful. Do any of these genera

cling to seaside? Are the other species of these genera wide rangers? Do

be a good Christian and not hate me.

I began last night to re-read your Galapagos paper, and to my taste it

is quite admirable: I see in it some of the points which I thought best

in A. De Candolle! Such is my memory.

Lyell will not express any opinion on continental extensions. (326/3.

See Letters 47, 48.)

LETTER 327. TO C. LYELL. Down, July 8th [1856].

Very many thanks for your two notes, and especially for Maury's map:

also for books which you are going to lend me.

I am sorry you cannot give any verdict on continental extensions; and

I infer that you think my argument of not much weight against such

extensions; I know I wish I could believe. (327/1. This paragraph is

published in the "Life and Letters," II., page 78; it refers to a letter

(June 25th, 1856, "Life and Letters," II., page 74) giving Darwin's

arguments against the doctrine of "Continental Extension." See Letters

47, 48.)

I have been having a look at Maury (which I once before looked at),

and in respect to Madeira & Co. I must say, that the chart seems to me

against land-extension explaining the introduction of organic beings.

Madeira, the Canaries and Azores are so tied together, that I should

have thought they ought to have been connected by some bank, if changes

of level had been connected with their organic relation. The Azores

ought, too, to have shown more connection with America. I had sometimes

speculated whether icebergs could account for the greater number

of European plants and their more northern character on the Azores,

compared with Madeira; but it seems dangerous until boulders are found

there. (327/2. See "Life and Letters," II., page 112, for a letter

(April 26th, 1858) in which Darwin exults over the discovery of

boulders on the Azores and the fulfilment of the prophecy, which he was

characteristically half inclined to ascribe to Lyell.)

One of the more curious points in Maury is, as it strikes me, in the

little change which about 9,000 feet of sudden elevation would make

in the continent visible, and what a prodigious change 9,000 feet

subsidence would make! Is the difference due to denudation during

elevation? Certainly 12,000 feet elevation would make a prodigious

change. I have just been quoting you in my essay on ice carrying seeds

in the southern hemisphere, but this will not do in all the cases. I

have had a week of such hard labour in getting up the relations of all

the Antarctic flora from Hooker's admirable works. Oddly enough, I have

just finished in great detail, giving evidence of coolness in tropical

regions during the Glacial epoch, and the consequent migration of

organisms through the tropics. There are a good many difficulties, but

upon the whole it explains much. This has been a favourite notion with

me, almost since I wrote on erratic boulders of the south. It harmonises

with the modification of species; and without admitting this awful

postulate, the Glacial epoch in the south and tropics does not work in

well. About Atlantis, I doubt whether the Canary Islands are as much

more related to the continent as they ought to be, if formerly connected

by continuous land.

Hooker, with whom I have formerly discussed the notion of the world

or great belts of it having been cooler, though he at first saw great

difficulties (and difficulties there are great enough), I think is

much inclined to adopt the idea. With modification of specific forms it

explains some wondrous odd facts in distribution.

But I shall never stop if I get on this subject, on which I have been at

work, sometimes in triumph, sometimes in despair, for the last month.

LETTER 328. ASA GRAY TO CHARLES DARWIN. Received August 20th, 1856.

I enclose you a proof of the last page, that you may see what our flora

amounts to. The genera of the Cryptogams (Ferns down to Hepaticae) are

illustrated in fourteen crowded plates. So that the volume has become

rather formidable as a class-book, which it is intended for.

I have revised the last proofs to-day. The publishers will bring it out

some time in August. Meanwhile, I am going to have a little holiday,

which I have earned, little as I can spare the time for it. And my wife

and I start on Friday to visit my mother and friends in West New York,

and on our way back I will look in upon the scientific meeting at Albany

on the 20th inst., or later, just to meet some old friends there.

Why could not you come over, on the urgent invitation given to European

savans--and free passage provided back and forth in the steamers? Yet

I believe nobody is coming. Will you not come next year, if a special

invitation is sent you on the same terms?

Boott lately sent me your photograph, which (though not a very perfect

one) I am well pleased to have...

But there is another question in your last letter--one about which a

person can only give an impression--and my impression is that, speaking

of plants of a well-known flora, what we call intermediate varieties are

generally less numerous in individuals than the two states which they

connect. That this would be the case in a flora where things are put as

they naturally should be, I do not much doubt; and the wider are

your views about species (say, for instance, with Dr. Hooker's very

latitudinarian notions) the more plainly would this appear. But

practically two things stand hugely in the way of any application of the

fact or principle, if such it be. 1. Our choice of what to take as the

typical forms very often is not free. We take, e.g., for one of them the

particular form of which Linnaeus, say, happened to have a specimen sent

him, and on which [he] established the species; and I know more than one

case in which that is a rare form of a common species; the other variety

will perhaps be the opposite extreme--whether the most common or not, or

will be what L. or [illegible] described as a 2nd species. Here various

intermediate forms may be the most abundant. 2. It is just the same

thing now, in respect to specimens coming in from our new western

country. The form which first comes, and is described and named,

determines the specific character, and this long sticks as the type,

though in fact it may be far from the most common form. Yet of plants

very well known in all their aspects, I can think of several of which

we recognise two leading forms, and rarely see anything really

intermediate, such as our Mentha borealis, its hairy and its smooth

varieties.

Your former query about the variability of naturalised plants as

compared with others of same genera, I had not forgotten, but have

taken no steps to answer. I was going hereafter to take up our list of

naturalised plants and consider them--it did not fall into my plan to

do it yet. Off-hand I can only say that it does not strike me that our

introduced plants generally are more variable, nor as variable, perhaps,

as the indigenous. But this is a mere guess. When you get my sheets of

first part of article in "Silliman's Journal," remember that I shall

be most glad of free critical comments; and the earlier I get them the

greater use they will be to me...

One more favour. Do not, I pray you, speak of your letters troubling me.

I should be sorry indeed to have you stop, or write more rarely, even

though mortified to find that I can so seldom give you the information

you might reasonably expect.

LETTER 329. TO ASA GRAY. Down, August 24th [1856].

I am much obliged for your letter, which has been very interesting to

me. Your "indefinite" answers are perhaps not the least valuable part;

for Botany has been followed in so much more a philosophical spirit

than Zoology, that I scarcely ever like to trust any general remark

in Zoology without I find that botanists concur. Thus, with respect to

intermediate varieties being rare, I found it put, as I suspected, much

too strongly (without the limitations and doubts which you point out) by

a very good naturalist, Mr. Wollaston, in regard to insects; and if it

could be established as true it would, I think, be a curious point.

Your answer in regard to the introduced plants not being particularly

variable, agrees with an answer which Mr. H.C. Watson has sent me in

regard to British agrarian plants, or such (whether or no naturalised)

[as] are now found only in cultivated land. It seems to me very odd,

without any theoretical notions of any kind, that such plants should not

be variable; but the evidence seems against it.

Very sincere thanks for your kind invitation to the United States: in

truth there is nothing which I should enjoy more; but my health is not,

and will, I suppose, never be strong enough, except for the quietest

routine life in the country. I shall be particularly glad of the sheets

of your paper on geographical distribution; but it really is unlikely in

the highest degree that I could make any suggestions.

With respect to my remark that I supposed that there were but few

plants common to Europe and the United States, not ranging to the

Arctic regions; it was founded on vague grounds, and partly on range of

animals. But I took H.C. Watson's remarks (1835) and in the table at the

end I found that out of 499 plants believed to be common to the Old and

New World, only 110 did not range on either side of the Atlantic up to

the Arctic region. And on writing to Mr. Watson to ask whether he knew

of any plants not ranging northward of Britain (say 55 deg) which were

in common, he writes to me that he imagines there are very few; with Mr.

Syme's assistance he found some 20 to 25 species thus circumstanced,

but many of them, from one cause or other, he considered doubtful. As

examples, he specifies to me, with doubt, Chrysosplenium oppositifolium;

Isnardia palustris; Astragalus hypoglottis; Thlaspi alpestre; Arenaria

verna; Lythrum hyssopifolium.

I hope that you will be inclined to work out for your next paper, what

number, of your 321 in common, do not range to Arctic regions. Such

plants seem exposed to such much greater difficulties in diffusion. Very

many thanks for all your kindness and answers to my questions.

P.S.--If anything should occur to you on variability of naturalised or

agrarian plants, I hope that you will be so kind as to let me hear, as

it is a point which interests me greatly.

LETTER 330. ASA GRAY TO CHARLES DARWIN. Cambridge, Mass., September

23rd, 1856.

Dr. Engelmann, of St. Louis, Missouri, who knew European botany well

before he came here, and has been an acute observer generally for twenty

years or more in this country, in reply to your question I put to him,

promptly said introduced plants are not particularly variable--are not

so variable as the indigenous plants generally, perhaps.

The difficulty of answering your questions, as to whether there are any

plants social here which are not so in the Old World, is that I know so

little about European plants in nature. The following is all I have

to contribute. Lately, I took Engelmann and Agassiz on a botanical

excursion over half a dozen miles of one of our seaboard counties; when

they both remarked that they never saw in Europe altogether half so much

barberry as in that trip. Through all this district B. vulgaris may be

said to have become a truly social plant in neglected fields and copses,

and even penetrating into rather close old woods. I always supposed that

birds diffused the seeds. But I am not clear that many of them touch the

berries. At least, these hang on the bushes over winter in the greatest

abundance. Perhaps the barberry belongs to a warmer country than north

of Europe, and finds itself more at home in our sunny summers. Yet out

of New England it seems not to spread at all.

Maruta Cotula, fide Engelmann, is a scattered and rather scarce plant in

Germany. Here, from Boston to St. Louis, it covers the roadsides, and is

one of our most social plants. But this plant is doubtless a native of a

hotter country than North Germany.

St. John's-wort (Hypericum perforatum) is an intrusive weed in all hilly

pastures, etc., and may fairly be called a social plant. In Germany it

is not so found, fide Engelmann.

Verbascum Thapsus is diffused over all the country, is vastly more

common here than in Germany, fide Engelmann.

I suppose Erodium cicutarium was brought to America with cattle from

Spain: it seems to be widely spread over South America out of the

Tropics. In Atlantic U.S. it is very scarce and local. But it fills

California and the interior of Oregon quite back to the west slope of

the Rocky Mountains. Fremont mentions it as the first spring food for

his cattle when he reached the western side of the Rocky Mountains. And

hardly anybody will believe me when I declare it an introduced plant. I

daresay it is equally abundant in Spain. I doubt if it is more so.

Engelmann and I have been noting the species truly indigenous here

which, becoming ruderal or campestral, are increasing in the number of

individuals instead of diminishing as the country becomes more settled

and forests removed. The list of our wild plants which have become true

weeds is larger than I had supposed, and these have probably all of them

increased their geographical range--at least, have multiplied in numbers

in the Northern States since settlements.

Some time ago I sent a copy of the first part of my little essay on

the statistics (330/1. "Statistics of the Flora of the Northern U.S."

("Silliman's Journal," XXII. and XXIII.)) of our Northern States plants

to Trubner & Co., 12, Paternoster Row, to be thence posted to you. It

may have been delayed or failed, so I post another from here.

This is only a beginning. Range of species in latitude must next be

tabulated--disjoined species catalogued (i.e. those occurring in

remote and entirely separated areas--e.g. Phryma, Monotropa uniflora,

etc.)--then some of the curious questions you have suggested--the degree

of consanguinity between the related species of our country and other

countries, and the comparative range of species in large and small

genera, etc., etc. Now, is it worth while to go on at this length of

detail? There is no knowing how much space it may cover. Yet, after all,

facts in all their fullness is what is wanted, and those not gathered

to support (or even to test) any foregone conclusions. It will be prosy,

but it may be useful.

Then I have no time properly to revise MSS. and correct oversights. To

my vexation, in my short list of our alpine species I have left out,

in some unaccountable manner, two of the most characteristic--viz.,

Cassiope hypnoides and Loiseleuria procumbens. Please add them on page

28.

There is much to be said about our introduced plants. But now, and for

some time to come, I must be thinking of quite different matters. I mean

to continue this essay in the January number--for which my MSS. must be

ready about the 1st of November.

I have not yet attempted to count them up; but of course I am prepared

to believe that fully three-fourths of our species common to Europe will

[be] found to range northward to the Arctic regions. I merely meant that

I had in mind a number that do not; I think the number will not be

very small; and I thought you were under the impression that very few

absolutely did not so extend northwards. The most striking case I know

is that of Convallaria majalis, in the mountains [of] Virginia and North

Carolina, and not northward. I believe I mentioned this to you before.

LETTER 331. TO ASA GRAY. Down, October 12th [1856].

I received yesterday your most kind letter of the 23rd and your

"Statistics," and two days previously another copy. I thank you

cordially for them. Botanists write, of course, for botanists; but, as

far as the opinion of an "outsider" goes, I think your paper admirable.

I have read carefully a good many papers and works on geographical

distribution, and I know of only one essay (viz. Hooker's "New Zealand")

that makes any approach to the clearness with which your paper makes a

non-botanist appreciate the character of the flora of a country. It

is wonderfully condensed (what labour it must have required!). You ask

whether such details are worth giving: in my opinion, there is literally

not one word too much.

I thank you sincerely for the information about "social" and "varying

plants," and likewise for giving me some idea about the proportion (i.e.

1/4th) of European plants which you think do not range to the extreme

North. This proportion is very much greater than I had anticipated, from

what I picked up in conversation, etc.

To return to your "Statistics." I daresay you will give how many genera

(and orders) your 260 introduced plants belong to. I see they include

113 genera non-indigenous. As you have probably a list of the introduced

plants, would it be asking too great a favour to send me, per Hooker

or otherwise, just the total number of genera and orders to which the

introduced plants belong. I am much interested in this, and have found

De Candolle's remarks on this subject very instructive.

Nothing has surprised me more than the greater generic and specific

affinity with East Asia than with West America. Can you tell me (and I

will promise to inflict no other question) whether climate explains this

greater affinity? or is it one of the many utterly inexplicable problems

in botanical geography? Is East Asia nearly as well known as West

America? so that does the state of knowledge allow a pretty fair

comparison? I presume it would be impossible, but I think it would make

in one point your tables of generic ranges more clear (admirably clear

as they seem to me) if you could show, even roughly, what proportion of

the genera in common to Europe (i.e. nearly half) are very general or

mundane rangers. As your results now stand, at the first glance the

affinity seems so very strong to Europe, owing, as I presume, to nearly

half of the genera including very many genera common to the world or

large portions of it. Europe is thus unfairly exalted. Is this not so?

If we had the number of genera strictly, or nearly strictly European,

one could compare better with Asia and Southern America, etc. But I dare

say this is a Utopian wish, owing to difficulty of saying what genera

to call mundane; nor have I my ideas at all clear on the subject, and I

have expressed them even less clearly than I have them.

I am so very glad that you intend to work out the north range of the 321

European species; for it seems to me the by far most important element

in their distribution.

And I am equally glad that you intend to work out range of species in

regard to size of genera--i.e. number of species in genus. I have been

attempting to do this in a very few cases, but it is folly for any one

but a botanist to attempt it. I must think that De Candolle has

fallen into error in attempting to do this for orders instead of for

genera--for reasons with which I will not trouble you.

LETTER 332. TO J.D. HOOKER.

(332/1. The "verdict" referred to in the following letter was Sir J.D.

Hooker's opinion on Darwin's MS. on geographical distribution. The first

paragraph has been already published in "Life and Letters," II., page

86.)

Down, November 4th [1856].

I thank you more cordially than you will think probable for your note.

Your verdict has been a great relief. On my honour I had no idea whether

or not you would say it was (and I knew you would say it very kindly)

so bad, that you would have begged me to have burnt the whole. To my own

mind my MS. relieved me of some few difficulties, and the difficulties

seemed to me pretty fairly stated; but I had become so bewildered with

conflicting facts--evidence, reasoning and opinions--that I felt

to myself that I had lost all judgment. Your general verdict is

incomparably more favourable than I had anticipated.

Very many thanks for your invitation. I had made up my mind, on my poor

wife's account, not to come up to next Phil. Club; but I am so much

tempted by your invitation, and my poor dear wife is so good-natured

about it, that I think I shall not resist--i.e., if she does not get

worse. I would come to dinner at about same time as before, if that

would suit you, and I do not hear to the contrary; and would go away by

the early train--i.e., about 9 o'clock. I find my present work tries me

a good deal, and sets my heart palpitating, so I must be careful. But

I should so much like to see Henslow, and likewise meet Lindley if

the fates will permit. You will see whether there will be time for any

criticism in detail on my MS. before dinner: not that I am in the

least hurry, for it will be months before I come again to Geographical

Distribution; only I am afraid of your forgetting any remarks.

I do not know whether my very trifling observations on means of

distribution are worth your reading, but it amuses me to tell them.

The seeds which the eagle had in [its] stomach for eighteen hours looked

so fresh that I would have bet five to one that they would all have

grown; but some kinds were ALL killed, and two oats, one canary-seed,

one clover, and one beet alone came up! Now I should have not cared

swearing that the beet would not have been killed, and I should have

fully expected that the clover would have been. These seeds, however,

were kept for three days in moist pellets, damp with gastric juice,

after being ejected, which would have helped to have injured them.

Lately I have been looking, during a few walks, at excrement of small

birds. I have found six kinds of seeds, which is more than I expected.

Lastly, I have had a partridge with twenty-two grains of dry earth on

one foot, and to my surprise a pebble as big as a tare seed; and I now

understand how this is possible, for the bird scratches itself, [and

the] little plumous feathers make a sort of very tenacious plaister.

Think of the millions of migratory quails (332/2. See "Origin," Edition

I., page 363, where the millions of migrating quails occur again.), and

it would be strange if some plants have not been transported across good

arms of the sea.

Talking of this, I have just read your curious Raoul Island paper.

(332/3. "Linn. Soc. Journal." I., 1857.) This looks more like a case of

continuous land, or perhaps of several intervening, now lost, islands

than any (according to my heterodox notions) I have yet seen. The

concordance of the vegetation seems so complete with New Zealand, and

with that land alone.

I have read Salter's paper and can hardly stomach it. I wonder whether

the lighters were ever used to carry grain and hay to ships. (332/4.

Salter, "Linn. Soc. Journal," I., 1857, page 140, "On the Vitality of

Seeds after prolonged Immersion in the Sea." It appears that in 1843 the

mud was scraped from the bottom of the channels in Poole Harbour, and

carried to shore in barges. On this mud a vegetation differing from that

of the surrounding shore sprang up.)

Adios, my dear Hooker. I thank you most honestly for your

assistance--assistance, by the way, now spread over some dozen years.

P.S.--Wednesday. I see from my wife's expression that she does not

really much like my going, and therefore I must give up, of course, this

pleasure.

If you should have anything to discuss about my MS., I see that I could

get to you by about 12, and then could return by the 2.19 o'clock train,

and be home by 5.30 o'clock, and thus I should get two hours' talk. But

it would be a considerable exertion for me, and I would not undertake it

for mere pleasure's sake, but would very gladly for my book's sake.

LETTER 333. J.D. HOOKER TO CHARLES DARWIN. November 9th, 1856.

I have finished the reading of your MS., and have been very much

delighted and instructed. Your case is a most strong one, and gives me

a much higher idea of change than I had previously entertained; and

though, as you know, never very stubborn about unalterability of

specific type, I never felt so shaky about species before.

The first half you will be able to put more clearly when you polish up.

I have in several cases made pencil alterations in details as to words,

etc., to enable myself to follow better,--some of it is rather stiff

reading. I have a page or two of notes for discussion, many of which

were answered, as I got further on with the MS., more or less fully.

Your doctrine of the cooling of the Tropics is a startling one, when

carried to the length of supporting plants of cold temperate regions;

and I must confess that, much as I should like it, I can hardly stomach

keeping the tropical genera alive in so very cool a greenhouse [pencil

note by C.D., "Not so very cool, but northern ones could range further

south if not opposed"]. Still I must confess that all your arguments pro

may be much stronger put than you have. I am more reconciled to iceberg

transport than I was, the more especially as I will give you any length

of time to keep vitality in ice, and more than that, will let you

transport roots that way also.

(333/1. The above letter was pinned to the following note by Mr.

Darwin.)

In answer to this show from similarity of American, and European and

Alpine-Arctic plants, that they have travelled enormously without any

change.

As sub-arctic, temperate and tropical are all slowly marching toward the

equator, the tropical will be first checked and distressed, similarly

(333/2. Almost illegible.) the temperate will invade...; after the

temperate can [not] advance or do not wish to advance further the

arctics will be checked and will invade. The temperates will have been

far longer in Tropics than sub-arctics. The sub-arctics will first have

to cross temperate [zone] and then Tropics. They would penetrate among

strangers, just like the many naturalised plants brought by man, from

some unknown advantage. But more, for nearly all have chance of doing

so.

(333/3. The point of view is more clearly given in the following

letters.)

LETTER 334. TO J.D. HOOKER. Down, November 15th [1856].

I shall not consider all your notes on my MS. for some weeks, till

I have done with crossing; but I have not been able to stop myself

meditating on your powerful objection to the mundane cold period (334/1.

See Letter 49.), viz. that MANY-fold more of the warm-temperate species

ought to have crossed the Tropics than of the sub-arctic forms. I really

think that to those who deny the modification of species this would

absolutely disprove my theory. But according to the notions which I am

testing--viz. that species do become changed, and that time is a most

important element (which I think I shall be able to show very clearly

in this case)--in such change, I think, the result would be as follows.

Some of the warm-temperate forms would penetrate the Tropics long before

the sub-arctic, and some might get across the equator long before the

sub-arctic forms could do so (i.e. always supposing that the cold came

on slowly), and therefore these must have been exposed to new associates

and new conditions much longer than the sub-arctic. Hence I should

infer that we ought to have in the warm-temperate S. hemisphere more

representative or modified forms, and fewer identical species than in

comparing the colder regions of the N. and S. I have expressed this

very obscurely, but you will understand, I think, what I mean. It is

a parallel case (but with a greater difference) to the species of the

mountains of S. Europe compared with the arctic plants, the S. European

alpine species having been isolated for a longer period than on the

arctic islands. Whether there are many tolerably close species in the

warm-temperate lands of the S. and N. I know not; as in La Plata, Cape

of Good Hope, and S. Australia compared to the North, I know not. I

presume it would be very difficult to test this, but perhaps you will

keep it a little before your mind, for your argument strikes me as

by far the most serious difficulty which has occurred to me. All your

criticisms and approvals are in simple truth invaluable to me. I fancy I

am right in speaking in this note of the species in common to N. and S.

as being rather sub-arctic than arctic.

This letter does not require any answer. I have written it to

ease myself, and to get you just to bear your argument, under the

modification point of view, in mind. I have had this morning a most

cruel stab in the side on my notion of the distribution of mammals in

relation to soundings.

LETTER 335. J.D. HOOKER TO CHARLES DARWIN. Kew, Sunday [November 1856].

I write only to say that I entirely appreciate your answer to my

objection on the score of the comparative rareness of Northern

warm-temperate forms in the Southern hemisphere. You certainly have

wriggled out of it by getting them more time to change, but as you must

admit that the distance traversed is not so great as the arctics have to

travel, and the extremes of modifying cause not so great as the arctics

undergo, the result should be considerably modified thereby. Thus: the

sub-arctics have (1) to travel twice as far, (2) taking twice the time,

(3) undergoing many more disturbing influences.

All this you have to meet by giving the North temperate forms simply

more time. I think this will hardly hold water.

LETTER 336. TO J.D. HOOKER. Down, November 18th [1856].

Many thanks for your note received this morning; and now for another

"wriggle." According to my notions, the sub-arctic species would advance

in a body, advancing so as to keep climate nearly the same; and as long

as they did this I do not believe there would be any tendency to change,

but only when the few got amongst foreign associates. When the tropical

species retreated as far as they could to the equator they would halt,

and then the confusion would spread back in the line of march from the

far north, and the strongest would struggle forward, etc., etc. (But

I am getting quite poetical in my wriggles). In short, I THINK the

warm-temperates would be exposed very much longer to those causes which

I believe are alone efficient in producing change than the sub-arctic;

but I must think more over this, and have a good wriggle. I cannot quite

agree with your proposition that because the sub-arctic have to travel

twice as far they would be more liable to change. Look at the two

journeys which the arctics have had from N. to S. and S. to N., with no

change, as may be inferred, if my doctrine is correct, from similarity

of arctic species in America and Europe and in the Alps. But I will not

weary you; but I really and truly think your last objection is not so

strong as it looks at first. You never make an objection without doing

me much good. Hurrah! a seed has just germinated after 21 1/2 hours in

owl's stomach. This, according to ornithologists' calculation, would

carry it God knows how many miles; but I think an owl really might go in

storm in this time 400 or 500 miles. Adios.

Owls and hawks have often been seen in mid-Atlantic.

(336/1. An interesting letter, dated November 23rd, 1856, occurs in the

"Life and Letters," II., page 86, which forms part of this discussion.

On page 87 the following passage occurs: "I shall have to discuss and

think more about your difficulty of the temperate and sub-arctic forms

in the S. hemisphere than I have yet done. But I am inclined to think

that I am right (if my general principles are right), that there would

be little tendency to the formation of a new species during the period

of migration, whether shorter or longer, though considerable variability

may have supervened.)

LETTER 337. TO J.D. HOOKER. Down, December 10th [1856].

It is a most tiresome drawback to my satisfaction in writing that,

though I leave out a good deal and try to condense, every chapter

runs to such an inordinate length. My present chapter on the causes of

fertility and sterility and on natural crossing has actually run out

to 100 pages MS., and yet I do not think I have put in anything

superfluous...

I have for the last fifteen months been tormented and haunted by

land-mollusca, which occur on every oceanic island; and I thought that

the double creationists or continental extensionists had here a complete

victory. The few eggs which I have tried both sink and are killed. No

one doubts that salt water would be eminently destructive to them; and I

was really in despair, when I thought I would try them when torpid; and

this day I have taken a lot out of the sea-water, after exactly seven

days' immersion. (337/1. This method of dispersal is not given in the

"Origin"; it seems, therefore, probable that further experiments upset

the conclusion drawn in 1856. This would account for the satisfaction

expressed in the following year at the discovery of another method, on

which Darwin wrote to Sir J.D. Hooker: "The distribution of fresh-water

molluscs has been a horrid incubus to me, but I think I know my way now.

When first hatched they are very active, and I have had thirty or forty

crawl on a dead duck's foot; and they cannot be jerked off, and

will live fifteen or even twenty-four hours out of water" ("Life and

Letters," II., page 93). The published account of these experiments is

in the "Origin," Edition I., page 385.) Some sink and some swim; and in

both cases I have had (as yet) one come to life again, which has quite

astonished and delighted me. I feel as if a thousand-pound weight was

taken off my back. Adios, my dear, kind friend.

I must tell you another of my profound experiments! [Frank] said to me:

"Why should not a bird be killed (by hawk, lightning, apoplexy, hail,

etc.) with seed in its crop, and it would swim?" No sooner said than

done: a pigeon has floated for thirty days in salt water with seeds in

its crop, and they have grown splendidly; and to my great surprise even

tares (Leguminosae, so generally killed by sea-water), which the bird

had naturally eaten, have grown well. You will say gulls and dog-fish,

etc., would eat up the carcase, and so they would 999 times out of

a thousand, but one might escape: I have seen dead land-birds in

sea-drift.

LETTER 338. ASA GRAY TO CHARLES DARWIN.

(338/1. In reply to Darwin's letter given in "Life and Letters," II.,

page 88.)

Cambridge, Mass., February 16th, 1857.

I meant to have replied to your interesting letter of January 1st long

before this time, and also that of November 24th, which I doubt if I

have ever acknowledged. But after getting my school-book, Lessons in

Botany, off my hands--it taking up time far beyond what its size would

seem to warrant--I had to fall hard at work upon a collection of small

size from Japan--mostly N. Japan, which I am only just done with. As

I expected, the number of species common to N. America is considerably

increased in this collection, as also the number of closely

representative species in the two, and a pretty considerable number of

European species too. I have packed off my MSS. (though I hardly know

what will become of it), or I would refer you to some illustrations. The

greater part of the identical species (of Japan and N. America) are of

those extending to or belonging to N.W. coast of America, but there

are several peculiar to Japan and E. U. States: e.g. our Viburnum

lantanoides is one of Thunberg's species. De Candolle's remarkable case

of Phryma, which he so dwells upon, turns out, as Dr. Hooker said

it would, to be only one out of a great many cases of the same sort.

(Hooker brought Monotropa uniflora, you know, from the Himalayas; and

now, by the way, I have it from almost as far south, i.e., from St. Fee,

New Granada)...

Well, I never meant to draw any conclusions at all, and am very sorry

that the only one I was beguiled into should "rile" (338/2. "One of your

conclusions makes me groan, viz., that the line of connection of the

strictly alpine plants is through Greenland. I should extremely like

to see your reasons published in detail, for it 'riles' me (this is a

proper expression, is it not?) dreadfully" (Darwin to Gray, January 1st,

1857, "Life and Letters," II., page 89).) you, as you say it does,--that

on page 73 of my second article: for if it troubles you it is not likely

to be sound. Of course I had no idea of laying any great stress upon the

fact (at first view so unexpected to me) that one-third of our alpine

species common to Europe do not reach the Arctic circle; but the remark

which I put down was an off-hand inference from what you geologists seem

to have settled--viz., that the northern regions must have been a deal

cooler than they are now--the northern limit of vegetation therefore

much lower than now--about the epoch when it would seem probable that

the existing species of our plants were created. At any rate, during

the Glacial period there could have been no phaenogamous plants on our

continent anywhere near the polar regions; and it seems a good rule to

look in the first place for the cause or reason of what now is, in that

which immediately preceded. I don't see that Greenland could help us

much, but if there was any interchange of species between N. America and

N. Europe in those times, was not the communication more likely to be in

lower latitudes than over the pole?

If, however, you say--as you may have very good reasons for saying--that

the existing species got their present diffusion before the Glacial

epoch, I should have no answer. I suppose you must needs assume very

great antiquity for species of plants in order to account for their

present dispersion, so long as we cling--as one cannot but do--to the

idea of the single birthplace of species.

I am curious to see whether, as you suggest, there would be found a

harmony or close similarity between the geographical range in

this country of the species common to Europe and those strictly

representative or strictly congeneric with European species. If I get

a little time I will look up the facts: though, as Dr. Hooker rightly

tells me, I have no business to be running after side game of any sort,

while there is so much I have to do--much more than I shall ever do

probably--to finish undertakings I have long ago begun.

...As to your P.S. If you have time to send me a longer list of your

protean genera, I will say if they seem to be protean here. Of those you

mention:--

Salix, I really know nothing about.

Rubus, the N. American species, with one exception, are very clearly

marked indeed.

Mentha, we have only one wild species; that has two pretty well-marked

forms, which have been taken for species; one smooth, the other hairy.

Saxifraga, gives no trouble here.

Myosotis, only one or two species here, and those very well marked.

Hieracium, few species, but pretty well marked.

Rosa, putting down a set of nominal species, leaves us four; two of them

polymorphous, but easy to distinguish...

LETTER 339. TO J.D. HOOKER. Down, [1857?]

One must judge by one's own light, however imperfect, and as I have

found no other book (339/1. A. De Candolle's "Geographie Botanique,"

1855.) so useful to me, I am bound to feel grateful: no doubt it is

in main part owing to the concentrated light of the noble art of

compilation. (339/2. See Letter 49.) I was aware that he was not the

first who had insisted on range of Monocots. (Was not R. Brown [with]

Flinders?) (339/3. M. Flinders' "Voyage to Terra Australis in 1801-3,

in H.M.S. 'Investigator'"; with "Botanical Appendix," by Robert Brown,

London, 1814.), and I fancy I only used expression "strongly insisted

on,"--but it is quite unimportant.

If you and I had time to waste, I should like to go over his [De

Candolle's] book and point out the several subjects in which I fancy he

is original. His remarks on the relations of naturalised plants will be

very useful to me; on the ranges of large families seemed to me good,

though I believe he has made a great blunder in taking families instead

of smaller groups, as I have been delighted to find in A. Gray's last

paper. But it is no use going on.

I do so wish I could understand clearly why you do not at all believe in

accidental means of dispersion of plants. The strongest argument which

I can remember at this instant is A. de C., that very widely ranging

plants are found as commonly on islands as over continents. It is really

provoking to me that the immense contrast in proportion of plants in New

Zealand and Australia seems to me a strong argument for non-continuous

land; and this does not seem to weigh in the least with you. I wish I

could put myself in your frame of mind. In Madeira I find in Wollaston's

books a parallel case with your New Zealand case--viz., the striking

absence of whole genera and orders now common in Europe, and (as I have

just been hunting out) common in Europe in Miocene periods. Of course

I can offer no explanation why this or that group is absent; but if the

means of introduction have been accidental, then one might expect odd

proportions and absences. When we meet, do try and make me see more

clearly than I do, your reasons.

LETTER 340. TO J.D. HOOKER. Down, November 14th [1858].

I am heartily glad to hear that my Lyellian notes have been of the

slightest use to you. (340/1. The Copley Medal was given to Sir Charles

Lyell in 1858. Mr. Darwin supplied Sir J.D. Hooker, who was on the

Council of the Royal Society, with notes for the reasons for the award.

See Letter 69.) I do not think the view is exaggerated...

Your letter and lists have MOST DEEPLY interested me. First for less

important point, about hermaphrodite trees. (340/2. See "Life and

Letters," II., page 89. In the "Origin," Edition I., page 100, the

author quotes Dr. Hooker to the effect that "the rule does not hold in

Australia," i.e., that trees are not more generally unisexual than other

plants. In the 6th edition, page 79, Darwin adds, "but if most of the

Australian trees are dichogamous, the same result would follow as if

they bore flowers with separated sexes.") It is enough to knock me down,

yet I can hardly think that British N. America and New Zealand should

all have been theoretically right by chance. Have you at Kew any

Eucalyptus or Australian Mimosa which sets its seeds? if so, would it

be very troublesome to observe when pollen is mature, and whether

pollen-tubes enter stigma readily immediately that pollen is mature or

some little time afterwards? though if pollen is not mature for some

little time after flower opens, the stigma might be ready first, though

according to C.C. Sprengel this is a rarer case. I wrote to Muller for

chance of his being able and willing to observe this.

Your fact of greater number of European plants (N.B.--But do you mean

greater percentage?) in Australia than in S. America is astounding and

very unpleasant to me; for from N.W. America (where nearly the

same flora exists as in Canada?) to T. del Fuego, there is far more

continuous high land than from Europe to Tasmania. There must have,

I should think, existed some curious barrier on American High-Road:

dryness of Peru, excessive damp of Panama, or some other confounded

cause, which either prevented immigration or has since destroyed them.

You say I may ask questions, and so I have on enclosed paper; but it

will of course be a very different thing whether you will think them

worth labour of answering.

May I keep the lists now returned? otherwise I will have them copied.

You said that you would give me a few cases of Australian forms

and identical species going north by Malay Archipelago mountains to

Philippines and Japan; but if these are given in your "Introduction"

this will suffice for me. (340/3. See Hooker's "Introductory Essay,"

page l.)

Your lists seem to me wonderfully interesting.

According to my theoretical notions, I am not satisfied with what you

say about local plants in S.W. corner of Australia (340/4. Sir Joseph

replied in an undated letter: "Thanks for your hint. I shall be very

cautious how I mention any connection between the varied flora and poor

soil of S.W. Australia...It is not by the way only that the species

are so numerous, but that these and the genera are so confoundedly well

marked. You have, in short, an incredible number of VERY LOCAL, WELL

MARKED genera and species crowded into that corner of Australia." See

"Introductory Essay to the Flora of Tasmania," 1859, page li.), and the

seeds not readily germinating: do be cautious on this; consider lapse

of time. It does not suit my stomach at all. It is like Wollaston's

confined land-snails in Porto Santo, and confined to same spots since

a Tertiary period, being due to their slow crawling powers; and yet we

know that other shell-snails have stocked a whole country within a very

few years with the same breeding powers, and same crawling powers,

when the conditions have been favourable to the life of the introduced

species. Hypothetically I should rather look at the case as owing

to--but as my notions are not very simple or clear, and only

hypothetical, they are not worth inflicting on you.

I had vowed not to mention my everlasting Abstract (340/5. The "Origin

of Species" was abbreviated from the MS. of an unpublished book.) to you

again, for I am sure I have bothered you far more than enough about

it; but as you allude to its previous publication I may say that I

have chapters on Instinct and Hybridism to abstract, which may take

a fortnight each; and my materials for Palaeontology, Geographical

Distribution and Affinities being less worked up, I daresay each of

these will take me three weeks, so that I shall not have done at soonest

till April, and then my Abstract will in bulk make a small volume. I

never give more than one or two instances, and I pass over briefly

all difficulties, and yet I cannot make my Abstract shorter, to be

satisfactory, than I am now doing, and yet it will expand to small

volume.

LETTER 341. TO J.D. HOOKER. Down [November?] 27th [1858].

What you say about the Cape flora's direct relation to Australia is a

great trouble to me. Does not Abyssinia highland, (341/1. In a letter

to Darwin, December 21st (?), 1858, Sir J.D. Hooker wrote: "Highlands of

Abyssinia will not help you to connect the Cape and Australian temperate

floras: they want all the types common to both, and, worse than that,

India notably wants them. Proteaceae, Thymeleae, Haemodoraceae, Acacia,

Rutaceae, of closely allied genera (and in some cases species), are

jammed up in S.W. Australia, and C.B.S. [Cape of Good Hope]: add to this

the Epacrideae (which are mere (paragraph symbol) of Ericaceae) and the

absence or rarity of Rasaceae, etc., etc., and you have an amount [of]

similarity in the floras and dissimilarity to that of Abyssinia and

India in the same features that does demand an explanation in any

theoretical history of Southern vegetation."), and the mountains on

W. coast in some degree connect the extra-tropical floras of Cape and

Australia? To my mind the enormous importance of the Glacial period

rises daily stronger and stronger. I am very glad to hear about S.E. and

S.W. Australia: I suspected after my letter was gone that the case must

be as it is. You know of course that nearly the same rule holds with

birds and mammals. Several years ago I reviewed in the "Annals of

Natural History," (341/2. "Annals and Mag. of Nat. Hist." Volume XIX.,

1847, pages 53-56, an unsigned review of "A Natural History of the

Mammalia," by G.R. Waterhouse, Volume I. The passage referred to is

at page 55: "The fact of South Australia possessing only few peculiar

species, it having been apparently colonised from the eastern and

western coasts, is very interesting; for we believe that Mr. Robert

Brown has shown that nearly the same remark is applicable to the plants;

and Mr. Gould finds that most of the birds from these opposite shores,

though closely allied, are distinct. Considering these facts, together

with the presence in South Australia of upraised modern Tertiary

deposits and of extinct volcanoes, it seems probable that the eastern

and western shores once formed two islands, separated from each other

by a shallow sea, with their inhabitants generically, though not

specifically, related, exactly as are those of New Guinea and Northern

Australia, and that within a geologically recent period a series of

upheavals converted the intermediate sea into those desert plains which

are now known to stretch from the southern coast far northward, and

which then became colonised from the regions to the east and west." On

this point see Hooker's "Introductory Essay to the Flora of Tasmania,"

page ci, where Jukes' views are discussed. For an interesting account

of the bearings of the submergence of parts of Australia, see

Thiselton-Dyer, "R. Geogr. Soc. Jour." XXII., No. 6.) Waterhouse's

"Mammalia," and speculated that these two corners, now separated by gulf

and low land, must have existed as two large islands; but it is odd that

productions have not become more mingled; but it accords with, I think,

a very general rule in the spreading of organic beings. I agree with

what you say about Lyell; he learns more by word of mouth than by

reading.

Henslow has just gone, and has left me in a fit of enthusiastic

admiration of his character. He is a really noble and good man.

LETTER 342. TO G. BENTHAM. Down, December 1st [1858?].

I thank you for so kindly taking the trouble of writing to me, on

naturalised plants. I did not know of, or had forgotten, the clover

case. How I wish I knew what plants the clover took the place of; but

that would require more accurate knowledge of any one piece of ground

than I suppose any one has. In the case of trees being so long-lived, I

should think it would be extremely difficult to distinguish between true

and new spreading of a species, and a rotation of crop. With respect to

your idea of plants travelling west, I was much struck by a remark of

yours in the penultimate "Linnean Journal" on the spreading of plants

from America near Behring Straits. Do you not consider so many more

seeds and plants being taken from Europe to America, than in a reverse

direction, would go some way to account for comparative fewness of

naturalised American plants here? Though I think one might wildly

speculate on European weeds having become well fitted for cultivated

land, during thousands of years of culture, whereas cultivated land

would be a new home for native American weeds, and they would not

consequently be able to beat their European rivals when put in contest

with them on cultivated land. Here is a bit of wild theory! (342/1.

See Asa Gray, "Scientific Papers," 1889, Volume II., page 235, on "The

Pertinacity and Predominance of Weeds," where the view here given is

adopted. In a letter to Asa Gray (November 6th, 1862), published in the

"Life and Letters," II., page 390, Darwin wrote: "Does it not hurt your

Yankee pride that we thrash you so confoundedly? I am sure Mrs. Gray

will stick up for your own weeds. Ask her whether they are not more

honest downright good sort of weeds.")

But I did not sit down intending to scribble thus; but to beg a favour

of you. I gave Hooker a list of species of Silene, on which Gartner has

experimentised in crossing: now I want EXTREMELY to be permitted to say

that such and such are believed by Mr. Bentham to be true species, and

such and such to be only varieties. Unfortunately and stupidly, Gartner

does not append author's name to the species.

Thank you heartily for what you say about my book; but you will be

greatly disappointed; it will be grievously too hypothetical. It will

very likely be of no other service than collocating some facts; though

I myself think I see my way approximately on the origin of species. But,

alas, how frequent, how almost universal it is in an author to persuade

himself of the truth of his own dogmas. My only hope is that I certainly

see very many difficulties of gigantic stature.

If you can remember any cases of one introduced species beating out or

prevailing over another, I should be most thankful to hear it. I believe

the common corn-poppy has been seen indigenous in Sicily. I should like

to know whether you suppose that seedlings of this wild plant would

stand a contest with our own poppy; I should almost expect that

our poppies were in some degree acclimatised and accustomed to our

cornfields. If this could be shown to be so in this and other cases, I

think we could understand why many not-trained American plants would not

succeed in our agrarian habitats.

LETTER 343. TO J.D. HOOKER.

(343/1. Mr. Darwin used the knowledge of the spread of introduced plants

in North America and Australia to throw light on the cosmic migration

of plants. Sir J.D. Hooker apparently objected that it was not fair

to argue from agrarian to other plants; he also took a view differing

slightly from that of Darwin as to climatal and other natural conditions

favouring introduced plants in Australia.)

Down, January 28th, 1859.

Thanks about glaciers. It is a pleasure and profit to me to write to

you, and as in your last you have touched on naturalised plants of

Australia, I suppose you would not dislike to hear what I can say

in answer. At least I know you would not wish me to defer to your

authority, as long as not convinced.

I quite agree to what you say about our agrarian plants being accustomed

to cultivated land, and so no fair test. Buckman has, I think, published

this notion with respect to North America. With respect to roadside

plants, I cannot feel so sure that these ought to be excluded, as

animals make roads in many wild countries. (343/2. In the account of

naturalised plants in Australia in Sir J.D. Hooker's "Introductory Essay

to the Flora of Tasmania," 1859, page cvi, many of the plants are marked

"Britain--waste places," "Europe--cornfields," etc. In the same list

the species which have also invaded North America--a large number--are

given. On the margin of Darwin's copy is scribbled in pencil: "Very

good, showing how many of the same species are naturalised in Australia

and United States, with very different climates; opposed to your

conclusion." Sir Joseph supposed that one chief cause of the intrusion

of English plants in Australia, and not vice versa, was the great

importation of European seed to Australia and the scanty return of

Australian seed.)

I have now looked and found passage in F. Muller's (343/3. Ferdinand

Muller.) letter to me, in which he says: "In the WILDERNESSES of

Australia some European perennials are "advancing in sure progress,"

"not to be arrested," etc. He gives as instances (so I suppose there

are other cases) eleven species, viz., 3. Rumex, Poterium sanguisorba,

Potentilla anserina, Medicago sativa, Taraxacum officinale, Marrubium

vulgare, Plantago lanceolata, P. major, Lolium perenne. All these are

seeding freely. Now I remember, years and years ago, your discussing

with me how curiously easily plants get naturalised on uninhabited

islands, if ships even touch there. I remember we discussed packages

being opened with old hay or straw, etc. Now think of hides and wool

(and wool exported largely over Europe), and plants introduced, and

samples of corn; and I must think that if Australia had been the old

country, and Europe had been the Botany Bay, very few, very much

fewer, Australian plants would have run wild in Europe than have now in

Australia.

The case seems to me much stronger between La Plata and Spain.

Nevertheless, I will put in my one sentence on this head, illustrating

the greater migration during Glacial period from north to south than

reversely, very humbly and cautiously. (343/4. "Origin of Species,"

Edition I., page 379. Darwin refers to the facts given by Hooker and De

Candolle showing a stronger migratory flow from north to south than in

the opposite direction. Darwin accounts for this by the northern plants

having been long subject to severe competition in their northern homes,

and having acquired a greater "dominating power" than the southern

forms. "Just in the same manner as we see at the present day that very

many European productions cover the ground in La Plata, and in a lesser

degree in Australia, and have to a certain extent beaten the natives;

whereas extremely few southern forms have become naturalised in any part

of Europe, though hides, wool, and other objects likely to carry seeds

have been largely imported during the last two or three centuries from

La Plata, and during the last thirty or forty years from Australia.')

I am very glad to hear you are making good progress with your Australian

Introduction. I am, thank God, more than half through my chapter on

geographical distribution, and have done the abstract of the Glacial

part...

LETTER 344. TO J.D. HOOKER. Down, March 30th, 1859.

Many thanks for your agreeable note. Please keep the geographical MS.

till you hear from me, for I may have to beg you to send it to Murray;

as through Lyell's intervention I hope he will publish, but he requires

first to see MS. (344/1. "The Origin of Species"; see a letter to Lyell

in "Life and Letters," II., page 151.)

I demur to what you say that we change climate of the world to account

for "migration of bugs, flies, etc." WE do nothing of the sort; for WE

rest on scored rocks, old moraines, arctic shells, and mammifers. I have

no theory whatever about cause of cold, no more than I have for cause of

elevation and subsidence; and I can see no reason why I should not use

cold, or elevation, or subsidence to explain any other phenomena, such

as distribution. I think if I had space and time I could make a pretty

good case against any great continental changes since the Glacial

epoch, and this has mainly led me to give up the Lyellian doctrine as

insufficient to explain all mutations of climate.

I was amused at the British Museum evidence. (344/2. This refers to the

letter to Murchison (Letter 65), published with the evidence of the 1858

enquiry by the Trustees of the British Museum.) I am made to give my

opinion so authoritatively on botanical matters!...

As for our belief in the origin of species making any difference in

descriptive work, I am sure it is incorrect, for I did all my barnacle

work under this point of view. Only I often groaned that I was not

allowed simply to decide whether a difference was sufficient to deserve

a name.

I am glad to hear about Huxley--a wonderful man.

LETTER 345. TO J.D. HOOKER. Wells Terrace, Ilkley, Otley, Yorkshire,

Thursday [before December 9th, 1859].

I have read your discussion (345/1. See "Introductory Essay," page

c. Darwin did not receive this work until December 23rd, so that the

reference is to proof-sheets.), as usual, with great interest. The

points are awfully intricate, almost at present beyond the confines

of knowledge. The view which I should have looked at as perhaps most

probable (though it hardly differs from yours) is that the whole world

during the Secondary ages was inhabited by marsupials, araucarias

(Mem.--Fossil wood so common of this nature in South America (345/2.

See Letter 6, Note.)), Banksia, etc.; and that these were supplanted and

exterminated in the greater area of the north, but were left alive in

the south. Whence these very ancient forms originally proceeded seems a

hopeless enquiry.

Your remarks on the passage of the northern forms southward, and of

the southern forms of no kinds passing northward, seem to me grand.

Admirable, also, are your remarks on the struggle of vegetation: I find

that I have rather misunderstood you, for I feared I differed from you,

which I see is hardly the case at all. I cannot help suspecting that you

put rather too much weight to climate in the case of Australia. La

Plata seems to present such analogous facts, though I suppose the

naturalisation of European plants has there taken place on a still

larger scale than in Australia...

You will get four copies of my book--one for self, and three for the

foreign botanists--in about ten days, or sooner; i.e., as soon as the

sheets can be bound in cloth. I hope this will not be too late for your

parcels.

When you read my volume, use your pencil and score, so that some time I

may have a talk with you on any criticisms.

LETTER 346. TO HUGH FALCONER. Down, December 17th, [1859].

Whilst I think of it, let me tell you that years ago I remember seeing

in the Museum of the Geological Society a tooth of hippopotamus from

Madagascar: this, on geographical and all other grounds, ought to be

looked to. Pray make a note of this fact. (346/1. At a meeting of the

Geological Society, May 1st, 1833, a letter was read from Mr. Telfair

to Sir Alex. Johnstone, accompanying a specimen of recent conglomerate

rock, from the island of Madagascar, containing fragments of a tusk, and

part of a molar tooth of a hippopotamus ("Proc. Geol. Soc." 1833, page

479). There is a reference to these remains of hippopotamus in a paper

by Mr. R.B. Newton in the "Geol. Mag." Volume X., 1893; and in Dr.

Forsyth Major's memoir on Megaladapis Madagascariensis ("Phil. Trans. R.

Soc." Volume 185, page 30, 1894).

Since this letter was written, several bones belonging to two or

possibly three species of hippopotamus have been found in Madagascar.

See Forsyth Major, "On the General Results of a Zoological Expedition to

Madagascar in 1894-96" ("Proc. Zool. Soc." 1896, page 971.))

We have returned a week ago from Ilkley, and it has done me some decided

good. In London I saw Lyell (the poor man who has "rushed into the

bosom of two heresies"--by the way, I saw his celts, and how intensely

interesting), and he told me that you were very antagonistic to my views

on species. I well knew this would be the case. I must freely confess,

the difficulties and objections are terrific; but I cannot believe that

a false theory would explain, as it seems to me it does explain, so

many classes of facts. Do you ever see Wollaston? He and you would agree

nicely about my book (346/2. "Origin of Species," 1859.)--ill luck to

both of you. If you have anything at all pleasant for me to hear, do

write; and if all that you can say is very unpleasant, it will do you

good to expectorate. And it is well known that you are very fond of

writing letters. Farewell, my good old friend and enemy.

Do make a note about the hippopotamus. If you are such a gentleman as to

write, pray tell me how Torquay agrees with your health.

(PLATE: DR. ASA GRAY, 1867.)

LETTER 347. TO ASA GRAY. Down, December 24th [1859].

I have been for ten weeks at Water-cure, and on my return a fortnight

ago through London I found a copy of your Memoir, and heartily do I

thank you for it. (347/1. "Diagnostic Characters of New Species

of Phaenogamous Plants collected in Japan by Charles Wright...with

Observations upon the Relations of the Japanese Flora to that of North

America and of other parts of the Northern Temperate Zone" ("Mem.

American Acad. Arts and Sci." Volume VI., page 377, 1857).) I have not

read it, and shall not be able very soon, for I am much overworked, and

my stomach has got nearly as bad as ever.

With respect to the discussion on climate, I beg you to believe that I

never put myself for a moment in competition with Dana; but when one

has thought on a subject, one cannot avoid forming some opinion. What

I wrote to Hooker I forget, after reading only a few sheets of your

Memoir, which I saw would be full of interest to me. Hooker asked me

to write to you, but, as I told him, I would not presume to express an

opinion to you without careful deliberation. What he wrote I know not:

I had previously several years ago seen (by whom I forget) some

speculation on warmer period in the U. States subsequent to Glacial

period; and I had consulted Lyell, who seemed much to doubt, and Lyell's

judgment is really admirably cautious. The arguments advanced in your

paper and in your letter seem to me hardly sufficient; not that I

should be at all sorry to admit this subsequent and intercalated warmer

period--the more changes the merrier, I think. On the other hand, I

do not believe that introduction of the Old World forms into New

World subsequent to the Glacial period will do for the modified or

representative forms in the two Worlds. There has been too much change

in comparison with the little change of isolated alpine forms; but you

will see this in my book. (347/2. "Origin of Species" (1859), Chapter

XI., pages 365 et seq.) I may just make a few remarks why at first sight

I do not attach much weight to the argument in your letter about the

warmer climate. Firstly, about the level of the land having been lower

subsequently to Glacial period, as evidenced by the whole, etc., I

doubt whether meteorological knowledge is sufficient for this deduction:

turning to the S. hemisphere, it might be argued that a greater extent

of water made the temperature lower; and when much of the northern land

was lower, it would have been covered by the sea and intermigration

between Old and New Worlds would have been checked. Secondly, I doubt

whether any inference on nature of climate can be deduced from extinct

species of mammals. If the musk-ox and deer of great size of your

Barren-Grounds had been known only by fossil bones, who would have

ventured to surmise the excessively cold climate they lived under? With

respect to food of large animals, if you care about the subject will you

turn to my discussion on this subject partly in respect to the Elephas

primigenius in my "Journal of Researches" (Murray's Home and Colonial

Library), Chapter V., page 85. (347/3. "The firm conviction of the

necessity of a vegetation possessing a character of tropical luxuriance

to support such large animals, and the impossibility of reconciling this

with the proximity of perpetual congelation, was one chief cause of

the several theories of sudden revolutions of climate...I am far from

supposing that the climate has not changed since the period when these

animals lived, which now lie buried in the ice. At present I only wish

to show that as far as quantity of food alone is concerned, the ancient

rhinoceroses might have roamed over the steppes of Central Siberia

even in their present condition, as well as the living rhinoceroses and

elephants over the karoos of Southern Africa" ("Journal of Researches,"

page 89, 1888).) In this country we infer from remains of Elephas

primigenius that the climate at the period of its embedment was very

severe, as seems countenanced by its woolly covering, by the nature

of the deposits with angular fragments, the nature of the co-embedded

shells, and co-existence of the musk-ox. I had formerly gathered from

Lyell that the relative position of the Megatherium and Mylodon with

respect to the Glacial deposits, had not been well made out; but perhaps

it has been so recently. Such are my reasons for not as yet admitting

the warmer period subsequent to Glacial epoch; but I daresay I may be

quite wrong, and shall not be at all sorry to be proved so.

I shall assuredly read your essay with care, for I have seen as yet

only a fragment, and very likely some parts, which I could not formerly

clearly understand, will be clear enough.

LETTER 348. TO J.D. HOOKER. Down, [December] 26th, [1859].

I have just read with intense interest as far as page xxvi (348/1. For

Darwin's impression of the "Introductory Essay to the Tasmanian Flora"

as a whole, see "Life and Letters," II., page 257.), i.e. to where you

treat of the Australian Flora itself; and the latter part I remember

thinking most of in the proof-sheets. Either you have altered a good

deal, or I did not see all or was purblind, for I have been much more

interested with all the first part than I was before,--not that I did

not like it at first. All seems to me very clearly written, and I have

been baulked at only one sentence. I think, on the whole, I like the

geological, or rather palaeontological, discussion best: it seems to me

excellent, and admirably cautious. I agree with all that you say as far

as my want of special knowledge allows me to judge.

I have no criticisms of any importance, but I should have liked more

facts in one or two places, which I shall not ask about. I rather demur

to the fairness of your comparison of rising and sinking areas (348/2.

Hooker, op. cit., page xv, paragraph 24. Hooker's view was that sinking

islands "contain comparatively fewer species and fewer peculiar generic

types than those which are rising." In Darwin's copy of the Essay is

written on the margin of page xvi: "I doubt whole case."), as in the

Indian Ocean you compare volcanic land with exclusively coral islands,

and these latter are very small in area and have very peculiar soil,

and during their formation are likely to have been utterly submerged,

perhaps many times, and restocked with existing plants. In the Pacific,

ignorance of Marianne and Caroline and other chief islands almost

prevent comparison (348/3. Gambier Island would be an interesting case.

[Note in original.]); and is it right to include American islands like

Juan Fernandez and Galapagos? In such lofty and probably ancient islands

as Sandwich and Tahiti it cannot make much difference in the flora

whether they have sunk or risen a few thousand feet of late ages.

I wish you could work in your notion of certain parts of the Tropics

having kept hot, whilst other parts were cooled; I tried this scheme in

my mind, and it seemed to fail. On the whole, I like very much all that

I have read of your Introduction, and I cannot doubt that it will

have great weight in converting other botanists from the doctrine of

immutable creation. What a lot of matter there is in one of your pages!

There are many points I wish much to discuss with you.

How I wish you could work out the Pacific floras: I remember ages

ago reading some of your MS. In Paris there must be, I should think,

materials from French voyages. But of all places in the world I

should like to see a good flora of the Sandwich Islands. (348/4. See

Hillebrand, "Flora of the Hawaiian Islands," 1888.) I would subscribe

50 pounds to any collector to go there and work at the islands. Would

it not pay for a collector to go there, especially if aided by any

subscription? It would be a fair occasion to ask for aid from the

Government grant of the Royal Society. I think it is the most isolated

group in the world, and the islands themselves well isolated from each

other.

LETTER 349. TO ASA GRAY. Down, January 7th [1860].

I have just finished your Japan memoir (349/1. "Diagnostic Characters of

New Species of Phaenogamous Plants collected in Japan by Charles Wright.

With observations upon the Relations of the Japanese Flora to that of

North America, etc.: 1857-59."--"Memoirs of Amer. Acad." VI.), and I

must thank you for the extreme interest with which I have read it. It

seems to me a most curious case of distribution; and how very well you

argue, and put the case from analogy on the high probability of single

centres of creation. That great man Agassiz, when he comes to reason,

seems to me as great in taking a wrong view as he is great in observing

and classifying. One of the points which has struck me as most

remarkable and inexplicable in your memoir is the number of monotypic

(or nearly so) genera amongst the representative forms of Japan and

N. America. And how very singular the preponderance of identical and

representative species in Eastern, compared with Western, America. I

have no good map showing how wide the moderately low country is on the

west side of the Rocky Mountains; nor, of course, do I know whether

the whole of the low western territory has been botanised; but it has

occurred to me, looking at such maps as I have, that the eastern area

must be larger than the western, which would account to a certain small

extent for preponderance on eastern side of the representative species.

Is there any truth in this suspicion? Your memoir sets me marvelling and

reflecting. I confess I am not able quite to understand your Geology at

pages 447, 448; but you would probably not care to hear my difficulties,

and therefore I will not trouble you with them.

I was so grieved to get a letter from Dana at Florence, giving me a very

poor (though improved) account of his health.

LETTER 350. TO T.H. HUXLEY. 15, Marine Parade, Eastbourne, November 1st

[1860].

Your note has been wonderfully interesting. Your term, "pithecoid man,"

is a whole paper and theory in itself. How I hope the skull of the new

Macrauchenia has come. It is grand. I return Hooker's letter, with very

many thanks. The glacial action on Lebanon is particularly interesting,

considering its position between Europe and Himalaya. I get more and

more convinced that my doctrine of mundane Glacial period is correct

(350/1. In the 1st edition of the "Origin," page 373, Darwin argues in

favour of a Glacial period practically simultaneous over the globe. In

the 5th edition, 1869, page 451, he adopted Mr. Croll's views on the

alternation of cold periods in the northern and southern hemispheres. An

interesting modification of the mundane Glacial period theory is given

in Belt's "The Naturalist in Nicaragua," 1874, page 265. Mr. Belt's

views are discussed in Wallace's "Geogr. Distribution," 1876, Volume I.,

page 151.), and that it is the most important of all late phenomena

with respect to distribution of plants and animals. I hope your Review

(350/2. The history of the foundation of the "Natural History Review"

is given in Huxley's "Life and Letters," Volume I., page 209. See Letter

107.) progresses favourably. I am exhausted and not well, so write

briefly; for we have had nine days of as much misery as man can endure.

My poor daughter has suffered pitiably, and night and day required three

persons to support her. The crisis of extreme danger is over, and she

is rallying surprisingly, but the doctors are yet doubtful of ultimate

issue. But the suffering was so pitiable I almost got to wish to see her

die. She is easy now. When she will be fit to travel home I know not.

I most sincerely hope that Mrs. Huxley keeps up pretty well. The work

which most men have to do is a blessing to them in such cases as yours.

God bless you.

Sir H. Holland came here to see her, and was wonderfully kind.

LETTER 351. TO C. LYELL. Down, November 20th [1860].

I quite agree in admiration of Forbes' Essay (351/1. "Memoir of the

Geolog. Survey of the United Kingdom," Volume I., 1846.), yet, on my

life, I think it has done, in some respects, as much mischief as good.

Those who believe in vast continental extensions will never investigate

means of distribution. Good heavens, look at Heer's map of Atlantis!

I thought his division and lines of travel of the British plants very

wild, and with hardly any foundation. I quite agree with what you say

of almost certainty of Glacial epoch having destroyed the Spanish

saxifrages, etc., in Ireland. (351/2. See Letter 20.) I remember well

discussing this with Hooker; and I suggested that a slightly different

or more equable and humid climate might have allowed (with perhaps some

extension of land) the plants in question to have grown along the entire

western shores between Spain and Ireland, and that subsequently they

became extinct, except at the present points under an oceanic climate.

The point of Devonshire now has a touch of the same character.

I demur in this particular case to Forbes' transportal by ice. The

subject has rather gone out of my mind, and it is not worth looking to

my MS. discussion on migration during the Glacial period; but I remember

that the distribution of mammalia, and the very regular relation of the

Alpine plants to points due north (alluded to in "Origin"), seemed to

indicate continuous land at close of Glacial period.

LETTER 352. TO J.D. HOOKER. Down, March 18th [1861].

I have been recalling my thoughts on the question whether the Glacial

period affected the whole world contemporaneously, or only one

longitudinal belt after another. To my sorrow my old reasons for

rejecting the latter alternative seem to me sufficient, and I should

very much like to know what you think. Let us suppose that the cold

affected the two Americas either before or after the Old World. Let

it advance first either from north or south till the Tropics became

slightly cooled, and a few temperate forms reached the Silla of Caracas

and the mountains of Brazil. You would say, I suppose, that nearly all

the tropical productions would be killed; and that subsequently, after

the cold had moderated, tropical plants immigrated from the other

non-chilled parts of the world. But this is impossible unless you bridge

over the tropical parts of the Atlantic--a doctrine which you know I

cannot admit, though in some respects wishing I could. Oswald Heer would

make nothing of such a bridge. When the Glacial period affected the

Old World, would it not be rather rash to suppose that the meridian

of India, the Malay Archipelago, and Australia were refrigerated, and

Africa not refrigerated? But let us grant that this was so; let us

bridge over the Red Sea (though rather opposed to the former almost

certain communication between the Red Sea and the Mediterranean); let

us grant that Arabia and Persia were damp and fit for the passage of

tropical plants: nevertheless, just look at the globe and fancy the cold

slowly coming on, and the plants under the tropics travelling towards

the equator, and it seems to me highly improbable that they could escape

from India to the still hot regions of Africa, for they would have to go

westward with a little northing round the northern shores of the Indian

Ocean. So if Africa were refrigerated first, there would be considerable

difficulty in the tropical productions of Africa escaping into the

still hot regions of India. Here again you would have to bridge over the

Indian Ocean within so very recent a period, and not in the line of

the Laccadive Archipelago. If you suppose the cold to travel from the

southern pole northwards, it will not help us, unless we suppose that

the countries immediately north of the northern tropic were at the same

time warmer, so as to allow free passage from India to Africa, which

seems to me too complex and unsupported an hypothesis to admit.

Therefore I cannot see that the supposition of different longitudinal

belts of the world being cooled at different periods helps us much.

The supposition of the whole world being cooled contemporaneously (but

perhaps not quite equally, South America being less cooled than the

Old World) seems to me the simplest hypothesis, and does not add to

the great difficulty of all the tropical productions not having been

exterminated. I still think that a few species of each still existing

tropical genus must have survived in the hottest or most favourable

spots, either dry or damp. The tropical productions, though much

distressed by the fall of temperature, would still be under the same

conditions of the length of the day, etc., and would be still exposed

to nearly the same enemies, as insects and other animals; whereas the

invading temperate productions, though finding a favouring temperature,

would have some of their conditions of life new, and would be exposed to

many new enemies. But I fully admit the difficulty to be very great.

I cannot see the full force of your difficulty of no known cause of

a mundane change of temperature. We know no cause of continental

elevations and depressions, yet we admit them. Can you believe, looking

to Europe alone, that the intense cold, which must have prevailed when

such gigantic glaciers extended on the plains of N. Italy, was due

merely to changed positions of land within so recent a period? I cannot.

It would be far too long a story, but it could, I think, be clearly

shown that all our continents existed approximately in their present

positions long before the Glacial period; which seems opposed to such

gigantic geographical changes necessary to cause such a vast fall of

temperature. The Glacial period endured in Europe and North America

whilst the level of the land oscillated in height fully 3,000 feet,

and this does not look as if changed level was the cause of the Glacial

period. But I have written an unreasonably long discussion. Do not

answer me at length, but send me a few words some time on the subject.

I have had this copied, that it might not bore you too much to read it.

A few words more. When equatorial productions were dreadfully distressed

by fall of temperature, and probably by changed humidity, and changed

proportional numbers of other plants and enemies (though they might

favour some of the species), I must admit that they all would be

exterminated if productions exactly fitted, not only for the climate,

but for all the conditions of the equatorial regions during the Glacial

period existed and could everywhere have immigrated. But the productions

of the temperate regions would have probably found, under the equator,

in their new homes and soils, considerably different conditions of

humidity and periodicity, and they would have encountered a new set of

enemies (a most important consideration); for there seems good reason

to believe that animals were not able to migrate nearly to the extent to

which plants did during the Glacial period. Hence I can persuade

myself that the temperate productions would not entirely replace and

exterminate the productions of the cooled tropics, but would become

partially mingled with them.

I am far from satisfied with what I have scribbled. I conclude that

there must have been a mundane Glacial period, and that the difficulties

are much the same whether we suppose it contemporaneous over the world,

or that longitudinal belts were affected one after the other. For

Heaven's sake forgive me!

LETTER 353. TO H.W. BATES. March 26th [1861].

I have been particularly struck by your remarks on the Glacial period.

(353/1. In his "Contributions to the Insect Fauna of the Amazon Valley,"

"Trans. Entom. Soc." Volume V., page 335 (read November 24th, 1860),

Mr. Bates discusses the migration of species from the equatorial regions

after the Glacial period. He arrives at a result which, he points

out, "is highly interesting as bearing upon the question of how far

extinction is likely to have occurred in equatorial regions during

the time of the Glacial epoch."..."The result is plain, that there

has always (at least throughout immense geological epochs) been an

equatorial fauna rich in endemic species, and that extinction cannot

have prevailed to any extent within a period of time so comparatively

modern as the Glacial epoch in geology." This conclusion does not

support the view expressed in the "Origin of Species" (Edition I.,