More Letters of Charles Darwin — Volume 1

If the identity of the land-shells of all the hundreds of British Isles be owing to their having been united since the Glacial period, and the discordance, almost total, of the shells of Porto Santo and Madeira be owing to their having been separated {during} all the newer and possibly older Pliocene periods, then it gives us a conception of time which will aid you much in your conversion of species, if immensity of time will do all you require; for the Glacial period is thus shown, as we might have anticipated, to be contemptible in duration or in distance from us, as compared to the older Pliocene, let alone the Miocene, when our contemporary species were, though in a minority, already beginning to flourish.

The littoral shells, according to MacAndrew, imply that Madeira and the Canaries were once joined to the mainland of Europe or Africa, but that those isles were disjoined so long ago that most of the species came in since. In short, the marine shells tell the same story as the land shells. Why do the plants of Porto Santo and Madeira agree so nearly? And why do the shells which are the same as European or African species remain quite unaltered, like the Crag species, which returned unchanged to the British seas after being expelled from them by glacial cold, when two millions (?) of years had elapsed, and after such migration to milder seas? Be so good as to explain all this in your next letter.

LETTER 48. TO J.D. HOOKER. Down, July 5th {1856}.

I write this morning in great tribulation about Tristan d'Acunha. (48/1. See "Flora Antarctica," page 216. Though Tristan d'Acunha is "only 1,000 miles distant from the Cape of Good Hope, and 3,000 from the Strait of Magalhaens, the botany of this island is far more intimately allied to that of Fuegia than Africa.") The more I reflect on your Antarctic flora the more I am astounded. You give all the facts so clearly and fully, that it is impossible to help speculating on the subject; but it drives me to despair, for I cannot gulp down your continent; and not being able to do so gives, in my eyes, the multiple creationists an awful triumph. It is a wondrous case, and how strange that A. De Candolle should have ignored it; which he certainly has, as it seems to me. I wrote Lyell a long geological letter (48/2. "Life and Letters," II., page 74.) about continents, and I have had a very long and interesting answer; but I cannot in the least gather his opinion about all your continental extensionists; and I have written again beseeching a verdict. (48/3. In the tenth edition of the "Principles," 1872, Lyell added a chapter (Chapter XLI., page 406) on insular floras and faunas in relation to the origin of species; he here (page 410) gives his reasons against Forbes as an extensionist.) I asked him to send to you my letter, for as it was well copied it would not be troublesome to read; but whether worth reading I really do not know; I have given in it the reasons which make me strongly opposed to continental extensions.

I was very glad to get your note some days ago: I wish you would think it worth while, as you intend to have the Laburnum case translated, to write to "Wien" (that unknown place) (48/4. There is a tradition that Darwin once asked Hooker where "this place Wien is, where they publish so many books."), and find out how the Laburnum has been behaving: it really ought to be known.

The Entada is a beast. (48/5. The large seeds of Entada scandens are occasionally floated across the Atlantic and cast on the shores of Europe.); I have never differed from you about the growth of a plant in a new island being a FAR harder trial than transportal, though certainly that seems hard enough. Indeed I suspect I go even further than you in this respect; but it is too long a story.

Thank you for the Aristolochia and Viscum cases: what species were they? I ask, because oddly these two very genera I have seen advanced as instances (I forget at present by whom, but by good men) in which the agency of insects was absolutely necessary for impregnation. In our British dioecious Viscum I suppose it must be necessary. Was there anything to show that the stigma was ready for pollen in these two cases? for it seems that there are many cases in which pollen is shed long before the stigma is ready. As in our Viscum, insects carry, sufficiently regularly for impregnation, pollen from flower to flower, I should think that there must be occasional crosses even in an hermaphrodite Viscum. I have never heard of bees and butterflies, only moths, producing fertile eggs without copulation.

With respect to the Ray Society, I profited so enormously by its publishing my Cirrepedia, that I cannot quite agree with you on confining it to translations; I know not how else I could possibly have published.

I have just sent in my name for 20 pounds to the Linnaean Society, but I must confess I have done it with heavy groans, whereas I daresay you gave your 20 pounds like a light-hearted gentleman...

P.S. Wollaston speaks strongly about the intermediate grade between two varieties in insects and mollusca being often rarer than the two varieties themselves. This is obviously very important for me, and not easy to explain. I believe I have had cases from you. But, if you believe in this, I wish you would give me a sentence to quote from you on this head. There must, I think, be a good deal of truth in it; otherwise there could hardly be nearly distinct varieties under any species, for we should have instead a blending series, as in brambles and willows.

LETTER 49. TO J.D. HOOKER. July 13th, 1856.

What a book a devil's chaplain might write on the clumsy, wasteful, blundering, low, and horribly cruel works of nature! With respect to crossing, from one sentence in your letter I think you misunderstand me. I am very far from believing in hybrids: only in crossing of the same species or of close varieties. These two or three last days I have been observing wheat, and have convinced myself that L. Deslongchamps is in error about impregnation taking place in closed flowers; i.e., of course, I can judge only from external appearances. By the way, R. Brown once told me that the use of the brush on stigma of grasses was unknown. Do you know its use?..

You say most truly about multiple creations and my notions. If any one case could be proved, I should be smashed; but as I am writing my book, I try to take as much pains as possible to give the strongest cases opposed to me, and often such conjectures as occur to me. I have been working your books as the richest (and vilest) mine against me; and what hard work I have had to get up your New Zealand Flora! As I have to quote you so often, I should like to refer to Muller's case of the Australian Alps. Where is it published? Is it a book? A correct reference would be enough for me, though it is wrong even to quote without looking oneself. I should like to see very much Forbes's sheets, which you refer to; but I must confess (I hardly know why) I have got rather to mistrust poor dear Forbes.

There is wonderful ill logic in his famous and admirable memoir on distribution, as it appears to me, now that I have got it up so as to give the heads in a page. Depend on it, my saying is a true one — viz. that a compiler is a great man, and an original man a commonplace man. Any fool can generalise and speculate; but oh, my heavens, to get up at second hand a New Zealand Flora, that is work...

And now I am going to beg almost as great a favour as a man can beg of another: and I ask some five or six weeks before I want the favour done, that it may appear less horrid. It is to read, but well copied out, my pages (about forty!!) on Alpine floras and faunas, Arctic and Antarctic floras and faunas, and the supposed cold mundane period. It would be really an enormous advantage to me, as I am sure otherwise to make botanical blunders. I would specify the few points on which I most want your advice. But it is quite likely that you may object on the ground that you might be publishing before me (I hope to publish in a year at furthest), so that it would hamper and bother you; and secondly you may object to the loss of time, for I daresay it would take an hour and a half to read. It certainly would be of immense advantage to me; but of course you must not think of doing it if it would interfere with your own work.

I do not consider this request in futuro as breaking my promise to give no more trouble for some time.

From Lyell's letters, he is coming round at a railway pace on the mutability of species, and authorises me to put some sentences on this head in my preface.

I shall meet Lyell on Wednesday at Lord Stanhope's, and will ask him to forward my letter to you; though, as my arguments have not struck him, they cannot have force, and my head must be crotchety on the subject; but the crotchets keep firmly there. I have given your opinion on continuous land, I see, too strongly.

LETTER 50. TO S.P. WOODWARD. Down, July 18th {1856}.

Very many thanks for your kindness in writing to me at such length, and I am glad to say for your sake that I do not see that I shall have to beg any further favours. What a range and what a variability in the Cyrena! (50/1. A genus of Lamellibranchs ranging from the Lias to the present day.) Your list of the ranges of the land and fresh-water shells certainly is most striking and curious, and especially as the antiquity of four of them is so clearly shown.

I have got Harvey's seaside book, and liked it; I was not particularly struck with it, but I will re-read the first and last chapters.

I am growing as bad as the worst about species, and hardly have a vestige of belief in the permanence of species left in me; and this confession will make you think very lightly of me, but I cannot help it. Such has become my honest conviction, though the difficulties and arguments against such heresy are certainly most weighty.

LETTER 51. TO C. LYELL. November 10th {1856}.

I know you like all cases of negative geological evidence being upset. I fancied that I was a most unwilling believer in negative evidence; but yet such negative evidence did seem to me so strong that in my "Fossil Lepadidae" I have stated, giving reasons, that I did not believe there could have existed any sessile cirripedes during the Secondary ages. Now, the other day Bosquet of Maestricht sends me a perfect drawing of a perfect Chthamalus (a recent genus) from the Chalk! (51/1. Chthamalus, a genus of Cirripedia. ("A Monograph on the Sub-class Cirripedia," by Charles Darwin, page 447. London, 1854.) A fossil species of this genus of Upper Cretaceous age was named by Bosquet Chthamalus Darwini. See "Origin," Edition VI., page 284; also Zittel, "Traite de Paleontologie," Traduit par Dr. C. Barrois, Volume II., page 540, figure 748. Paris, 1887.) Indeed, it is stretching a point to make it specifically distinct from our living British species. It is a genus not hitherto found in any Tertiary bed.

LETTER 52. TO T.H. HUXLEY. Down, July 9th, 1857.

I am extremely much obliged to you for having so fully entered on my point. I knew I was on unsafe ground, but it proves far unsafer than I had thought. I had thought that Brulle (52/1. This no doubt refers to A. Brulle's paper in the "Comptes rendus" 1844, of which a translation is given in the "Annals and Mag. of Natural History," 1844, page 484. In speaking of the development of the Articulata, the author says "that the appendages are manifested at an earlier period of the existence of an Articulate animal the more complex its degree of organisation, and vice versa that they make their appearance the later, the fewer the number of transformations which it has to undergo.") had a wider basis for his generalisation, for I made the extract several years ago, and I presume (I state it as some excuse for myself) that I doubted it, for, differently from my general habit, I have not extracted his grounds. It was meeting with Barneoud's paper which made me think there might be truth in the doctrine. (52/2. Apparently Barneoud "On the Organogeny of Irregular Corollas," from the "Comptes rendus," 1847, as given in "Annals and Mag. of Natural History," 1847, page 440. The paper chiefly deals with the fact that in their earliest condition irregular flowers are regular. The view attributed to Barneoud does not seem so definitely given in this paper as in a previous one ("Ann. Sc. Nat." Bot., Tom. VI., page 268.) Your instance of heart and brain of fish seems to me very good. It was a very stupid blunder on my part not thinking of the posterior part of the time of development. I shall, of course, not allude to this subject, which I rather grieve about, as I wished it to be true; but, alas! a scientific man ought to have no wishes, no affections — a mere heart of stone.

There is only one point in your letter which at present I cannot quite follow you in: supposing that Barneoud's (I do not say Brulle's) remarks were true and universal — i.e., that the petals which have to undergo the greatest amount of development and modification begin to change the soonest from the simple and common embryonic form of the petal — if this were a true law, then I cannot but think that it would throw light on Milne Edwards' proposition that the wider apart the classes of animals are, the sooner do they diverge from the common embryonic plan — which common embryonic {plan} may be compared with the similar petals in the early bud, the several petals in one flower being compared to the distinct but similar embryos of the different classes. I much wish that you would so far keep this in mind, that whenever we meet I might hear how far you differ or concur in this. I have always looked at Barneoud's and Brulle's proposition as only in some degree analogous.

P.S. I see in my abstract of Milne Edwards' paper, he speaks of "the most perfect and important organs" as being first developed, and I should have thought that this was usually synonymous with the most developed or modified.

LETTER 53. TO J.D. HOOKER.

(53/1. The following letter is chiefly of interest as showing the amount and kind of work required for Darwin's conclusions on "large genera varying," which occupy no more than two or three pages in the "Origin" (Edition I., page 55). Some correspondence on the subject is given in the "Life and Letters," II., pages 102-5.)

Down, August 22nd {1857}.

Your handwriting always rejoices the cockles of my heart; though you have no reason to be "overwhelmed with shame," as I did not expect to hear.

I write now chiefly to know whether you can tell me how to write to Hermann Schlagenheit (is this spelt right?) (53/2. Schlagintweit.), for I believe he is returned to England, and he has poultry skins for me from W. Elliot of Madras.

I am very glad to hear that you have been tabulating some Floras about varieties. Will you just tell me roughly the result? Do you not find it takes much time? I am employing a laboriously careful schoolmaster, who does the tabulating and dividing into two great cohorts, more carefully than I can. This being so, I should be very glad some time to have Koch, Webb's Canaries, and Ledebour, and Grisebach, but I do not know even where Rumelia is. I shall work the British flora with three separate Floras; and I intend dividing the varieties into two classes, as Asa Gray and Henslow give the materials, and, further, A. Gray and H.C. Watson have marked for me the forms, which they consider real species, but yet are very close to others; and it will be curious to compare results. If it will all hold good it is very important for me; for it explains, as I think, all classification, i.e. the quasi-branching and sub-branching of forms, as if from one root, big genera increasing and splitting up, etc., as you will perceive. But then comes in, also, what I call a principle of divergence, which I think I can explain, but which is too long, and perhaps you would not care to hear. As you have been on this subject, you might like to hear what very little is complete (for my schoolmaster has had three weeks' holidays) — only three cases as yet, I see.

BABINGTON — British Flora.

(*53/3. This sentence may be interpreted as follows: The number of species which present varieties are 134 per thousand in genera of 5 species and upwards. The result is obtained from tabulation of 593 species.)

HOOKER — New Zealand.

GODRON — Central France.

I do not enter into details on omitting introduced plants and very varying genera, as Rubus, Salix, Rosa, etc., which would make the result more in favour.

I enjoyed seeing Henslow extremely, though I was a good way from well at the time. Farewell, my dear Hooker: do not forget your visit here some time.

LETTER 54. TO J.D. HOOKER. Down, November 14th {1857}.

On Tuesday I will send off from London, whither I go on that day, Ledebour's three remaining volumes, Grisebach and Cybele, i.e., all that I have, and most truly am I obliged to you for them. I find the rule, as yet, of the species varying most in the large genera universal, except in Miquel's very brief and therefore imperfect list of the Holland flora, which makes me very anxious to tabulate a fuller flora of Holland. I shall remain in London till Friday morning, and if quite convenient to send me two volumes of D.C. Prodromus, I could take them home and tabulate them. I should think a volume with a large best known natural family, and a volume with several small broken families would be best, always supposing that the varieties are conspicuously marked in both. Have you the volume published by Lowe on Madeira? If so and if any varieties are marked I should much like to see it, to see if I can make out anything about habitats of vars. in so small an area — a point on which I have become very curious. I fear there is no chance of your possessing Forbes and Hancock "British Shells," a grand work, which I much wish to tabulate.

Very many thanks for seed of Adlumia cirrhosa, which I will carefully observe. My notice in the G. Ch. on Kidney Beans (54.1 "On the Agency of Bees in the Fertilisation of Papilionaceous Flowers" ("Gardeners' Chronicle," 1857, page 725).) has brought me a curious letter from an intelligent gardener, with a most remarkable lot of beans, crossed in a marvellous manner IN THE FIRST GENERATION, like the peas sent to you by Berkeley and like those experimentalised on by Gartner and by Wiegmann. It is a very odd case; I shall sow these seeds and see what comes up. How very odd that pollen of one form should affect the outer coats and size of the bean produced by pure species!..

LETTER 55. TO J.D. HOOKER. Down {1857?}.

You know how I work subjects: namely, if I stumble on any general remark, and if I find it confirmed in any other very distinct class, then I try to find out whether it is true, — if it has any bearing on my work. The following, perhaps, may be important to me. Dr. Wight remarks that Cucurbitaceae (55/1. Wight, "Remarks on the Fruit of the Natural Order Cucurbitaceae" ("Ann. Mag. Nat. Hist." VIII., page 261). R. Wight, F.R.S. (1796-1872) was Superintendent of the Madras Botanic Garden.) is a very isolated family, and has very diverging affinities. I find, strongly put and illustrated, the very same remark in the genera of hymenoptera. Now, it is not to me at first apparent why a very distinct and isolated group should be apt to have more divergent affinities than a less isolated group. I am aware that most genera have more affinities than in two ways, which latter, perhaps, is the commonest case. I see how infinitely vague all this is; but I should very much like to know what you and Mr. Bentham (if he will read this), who have attended so much to the principles of classification, think of this. Perhaps the best way would be to think of half a dozen most isolated groups of plants, and then consider whether the affinities point in an unusual number of directions. Very likely you may think the whole question too vague to be worth consideration.

LETTER 56. TO J.D. HOOKER. Down, April 8th {1857}.

I now want to ask your opinion, and for facts on a point; and as I shall often want to do this during the next year or two, so let me say, once for all, that you must not take trouble out of mere good nature (of which towards me you have a most abundant stock), but you must consider, in regard to the trouble any question may take, whether you think it worth while — as all loss of time so far lessens your original work — to give me facts to be quoted on your authority in my work. Do not think I shall be disappointed if you cannot spare time; for already I have profited enormously from your judgment and knowledge. I earnestly beg you to act as I suggest, and not take trouble solely out of good-nature.

My point is as follows: Harvey gives the case of Fucus varying remarkably, and yet in same way under most different conditions. D. Don makes same remark in regard to Juncus bufonius in England and India. Polygala vulgaris has white, red, and blue flowers in Faroe, England, and I think Herbert says in Zante. Now such cases seem to me very striking, as showing how little relation some variations have to climatal conditions.

Do you think there are many such cases? Does Oxalis corniculata present exactly the same varieties under very different climates?

How is it with any other British plants in New Zealand, or at the foot of the Himalaya? Will you think over this and let me hear the result?

One other question: do you remember whether the introduced Sonchus in New Zealand was less, equally, or more common than the aboriginal stock of the same species, where both occurred together? I forget whether there is any other case parallel with this curious one of the Sonchus...

I have been making good, though slow, progress with my book, for facts have been falling nicely into groups, enlightening each other.

LETTER 57. TO T.H. HUXLEY. Moor Park, Farnham, Surrey {1857?}.

Your letter has been forwarded to me here, where I am profiting by a few weeks' rest and hydropathy. Your letter has interested and amused me much. I am extremely glad you have taken up the Aphis (57/1. Professor Huxley's paper on the organic reproduction of Aphis is in the "Trans. Linn. Soc." XXII. (1858), page 193. Prof. Owen had treated the subject in his introductory Hunterian lecture "On Parthenogenesis" (1849). His theory cannot be fully given here. Briefly, he holds that parthenogenesis is due to the inheritance of a "remnant of spermatic virtue": when the "spermatic force" or "virtue" is exhausted fresh impregnation occurs. Huxley severely criticises both Owen's facts and his theory.) question, but, for Heaven's sake, do not come the mild Hindoo (whatever he may be) to Owen; your father confessor trembles for you. I fancy Owen thinks much of this doctrine of his; I never from the first believed it, and I cannot but think that the same power is concerned in producing aphides without fertilisation, and producing, for instance, nails on the amputated stump of a man's fingers, or the new tail of a lizard. By the way, I saw somewhere during the last week or so a statement of a man rearing from the same set of eggs winged and wingless aphides, which seemed new to me. Does not some Yankee say that the American viviparous aphides are winged? I am particularly glad that you are ruminating on the act of fertilisation: it has long seemed to me the most wonderful and curious of physiological problems. I have often and often speculated for amusement on the subject, but quite fruitlessly. Do you not think that the conjugation of the Diatomaceae will ultimately throw light on the subject? But the other day I came to the conclusion that some day we shall have cases of young being produced from spermatozoa or pollen without an ovule. Approaching the subject from the side which attracts me most, viz., inheritance, I have lately been inclined to speculate, very crudely and indistinctly, that propagation by true fertilisation will turn out to be a sort of mixture, and not true fusion, of two distinct individuals, or rather of innumerable individuals, as each parent has its parents and ancestors. I can understand on no other view the way in which crossed forms go back to so large an extent to ancestral forms. But all this, of course, is infinitely crude. I hope to be in London in the course of this month, and there are two or three points which, for my own sake, I want to discuss briefly with you.