LETTER 546. TO J. CROLL. Down, August 9th, 1877.

I am much obliged for your essay, which I have read with the greatest interest. With respect to the geological part, I have long wished to see the evidence collected on the time required for denudation, and you have done it admirably. (546/1. In a paper "On the Tidal Retardation Argument for the Age of the Earth" ("Brit. Assoc. Report," 1876, page 88), Croll reverts to the influence of subaerial denudation in altering the form of the earth as an objection to the argument from tidal retardation. He had previously dealt with this subject in "Climate and Time," Chapter XX., London, 1875.) I wish some one would in a like spirit compare the thickness of sedimentary rocks with the quickest estimated rate of deposition by a large river, and other such evidence. Your main argument with respect to the sun seems to me very striking.

My son George desires me to thank you for his copy, and to say how much he has been interested by it.

2.IX.VII. GEOLOGICAL ACTION OF EARTHWORMS, 1880-1882.

"My whole soul is absorbed with worms just at present." (From a letter to Sir W. Thistleton-Dyer, November 26th, 1880.)

LETTER 547. TO T.H. FARRER (Lord Farrer).

(547/1. The five following letters, written shortly before and after the publication of "The Formation of Vegetable Mould through the Action of Worms," 1881, deal with questions connected with Mr. Darwin's work on the habits and geological action of earthworms.)

Down, October 20th, 1880.

What a man you are to do thoroughly whatever you undertake to do! The supply of specimens has been magnificent, and I have worked at them for a day and a half. I find a very few well-rounded grains of brick in the castings from over the gravel walk, and plenty over the hole in the field, and over the Roman floor. (547/2. See "The Formation of Vegetable Mould," 1881, pages 178 et seq. The Roman remains formed part of a villa discovered at Abinger, Surrey. Excavations were carried out, under Lord Farrer's direction, in a field adjoining the ground in which the Roman villa was first found, and extended observations were made by Lord Farrer, which led Mr. Darwin to conclude that a large part of the fine vegetable mould covering the floor of the villa had been brought up from below by worms.) You have done me the greatest possible service by making me more cautious than I should otherwise have been—viz., by sending me the rubbish from the road itself; in this rubbish I find very many particles, rounded (I suppose) by having been crushed, angles knocked off, and somewhat rolled about. But not a few of the particles may have passed through the bodies of worms during the years since the road was laid down. I still think that the fragments are ground in the gizzards of worms, which always contain bits of stone; but I must try and get more evidence. I have to-day started a pot with worms in very fine soil, with sharp fragments of hard tiles laid on the surface, and hope to see in the course of time whether any of those become rounded. I do not think that more specimens from Abinger would aid me...

LETTER 548. TO G.J. ROMANES. Down, March 7th.

I was quite mistaken about the "Gardeners' Chronicle;" in my index there are only the few enclosed and quite insignificant references having any relation to the minds of animals. When I returned to my work, I found that I had nearly completed my statement of facts about worms plugging up their burrows with leaves (548/1. Chapter II., of "The Formation of Vegetable Mould through the Action of Worms," 1881, contains a discussion on the intelligence shown by worms in the manner of plugging up their burrows with leaves (pages 78 et seq.).), etc., etc., so I waited until I had naturally to draw up a few concluding remarks. I hope that it will not bore you to read the few accompanying pages, and in the middle you will find a few sentences with a sort of definition of, or rather discussion on, intelligence. I am altogether dissatisfied with it. I tried to observe what passed in my own mind when I did the work of a worm. If I come across a professed metaphysician, I will ask him to give me a more technical definition, with a few big words about the abstract, the concrete, the absolute, and the infinite; but seriously, I should be grateful for any suggestions, for it will hardly do to assume that every fool knows what "intelligent" means. (548/2. "Mr. Romanes, who has specially studied the minds of animals, believes that we can safely infer intelligence only when we see an individual profiting by its own experience...Now, if worms try to drag objects into their burrows, first in one way and then in another, until they at last succeed, they profit, at least in each particular instance, by experience" ("The Formation of Vegetable Mould," 1881, page 95).) You will understand that the MS. is only the first rough copy, and will need much correction. Please return it, for I have no other copy—only a few memoranda. When I think how it has bothered me to know what I mean by "intelligent," I am sorry for you in your great work on the minds of animals.

I daresay that I shall have to alter wholly the MS.

LETTER 549. TO FRANCIS GALTON. Down, March 8th [1881].

Very many thanks for your note. I have been observing the [worm] tracks on my walks for several months, and they occur (or can be seen) only after heavy rain. As I know that worms which are going to die (generally from the parasitic larva of a fly) always come out of their burrows, I have looked out during these months, and have usually found in the morning only from one to three or four along the whole length of my walks. On the other hand, I remember having in former years seen scores or hundreds of dead worms after heavy rain. (549/1. "After heavy rain succeeding dry weather, an astonishing number of dead worms may sometimes be seen lying on the ground. Mr. Galton informs me that on one occasion (March, 1881), the dead worms averaged one for every two-and-a-half paces in length on a walk in Hyde Park, four paces in width" (loc. cit., page 14).) I cannot possibly believe that worms are drowned in the course of even three or four days' immersion; and I am inclined to conclude that the death of sickly (probably with parasites) worms is thus hastened. I will add a few words to what I have said about these tracks. Occasionally worms suffer from epidemics (of what nature I know not) and die by the million on the surface of the ground. Your ruby paper answers capitally, but I suspect that it is only for dimming the light, and I know not how to illuminate worms by the same intensity of light, and yet of a colour which permits the actinic rays to pass. I have tried drawing triangles of damp paper through a small cylindrical hole, as you suggested, and I can discover no source of error. (549/2. Triangles of paper were used in experiments to test the intelligence of worms (loc. cit., page 83).) Nevertheless, I am becoming more doubtful about the intelligence of worms. The worst job is that they will do their work in a slovenly manner when kept in pots (549/3. Loc. cit., page 75.), and I am beyond measure perplexed to judge how far such observations are trustworthy.

LETTER 550. TO E. RAY LANKESTER.

(550/1. Mr. Lankester had written October 11th, 1881, to thank Mr. Darwin for the present of the Earthworm book. He asks whether Darwin knows of "any experiments on the influence of sea-water on earthworms. I have assumed that it is fatal to them. But there is a littoral species (Pontodrilus of Perrier) found at Marseilles." Lankester adds, "It is a great pleasure and source of pride to me to see my drawing of the earthworm's alimentary canal figuring in your pages."

Down, October 13th [1881].

I have been much pleased and interested by your note. I never actually tried sea-water, but I was very fond of angling when a boy, and as I could not bear to see the worms wriggling on the hook, I dipped them always first in salt water, and this killed them very quickly. I remember, though not very distinctly, seeing several earthworms dead on the beach close to where a little brook entered, and I assumed that they had been brought down by the brook, killed by the sea-water, and cast on shore. With your skill and great knowledge, I have no doubt that you will make out much new about the anatomy of worms, whenever you take up the subject again.

LETTER 551. TO J.H. GILBERT. Down, January, 12th, 1882.

I have been much interested by your letter, for which I thank you heartily. There was not the least cause for you to apologise for not having written sooner, for I attributed it to the right cause, i.e. your hands being full of work.

Your statement about the quantity of nitrogen in the collected castings is most curious, and much exceeds what I should have expected. In lately reading one of your and Mr. Lawes' great papers in the "Philosophical Transactions" (551/1. The first Report on "Agricultural, Botanical, and Chemical Results of Experiments on the Mixed Herbage of Permanent Grassland, conducted for many years in succession on the same land," was published in the "Philosophical Transactions of the Royal Society" in 1880, the second paper appeared in the "Phil. Trans." for 1882, and the third in the "Phil. Trans." of 1900, Volume 192, page 139.) (the value and importance of which cannot, in my opinion, be exaggerated) I was struck with the similarity of your soil with that near here; and anything observed here would apply to your land. Unfortunately I have never made deep sections in this neighbourhood, so as to see how deep the worms burrow, except in one spot, and here there had been left on the surface of the chalk a little very fine ferruginous sand, probably of Tertiary age; into this the worms had burrowed to a depth of 55 and 61 inches. I have never seen here red castings on the surface, but it seems possible (from what I have observed with reddish sand) that much of the red colour of the underlying clay would be discharged in passing through the intestinal canal.

Worms usually work near the surface, but I have noticed that at certain seasons pale-coloured earth is brought up from beneath the outlying blackish mould on my lawn; but from what depth I cannot say. That some must be brought up from a depth of four or five or six feet is certain, as the worms retire to this depth during very dry and very cold weather. As worms devour greedily raw flesh and dead worms, they could devour dead larvae, eggs, etc., etc., in the soil, and thus they might locally add to the amount of nitrogen in the soil, though not of course if the whole country is considered. I saw in your paper something about the difference in the amount of nitrogen at different depths in the superficial mould, and here worms may have played a part. I wish that the problem had been before me when observing, as possibly I might have thrown some little light on it, which would have pleased me greatly.

2.IX.VIII. MISCELLANEOUS, 1846-1878.

(552/1. The following four letters refer to questions connected with the origin of coal.)

LETTER 552. TO J.D. HOOKER. Down, May [1846].

I am delighted that you are in the field, geologising or palaeontologising. I beg you to read the two Rogers' account of the Coal-fields of N. America; in my opinion they are eminently instructive and suggestive. (552/1. "On the Physical Structure of the Appalachian Chain," by W.B. and H.D. Rogers. Boston, 1843. See also "Geology of Pennsylvania," by H.D. Rogers. 4 volumes. London and Philadelphia, 1843.) I can lend you their resume of their own labours, and, indeed, I do not know that their work is yet published in full. L. Horner gives a capital balance of difficulties on the Coal-theory in his last Anniversary Address, which, if you have not read, will, I think, interest you. (552/2. "Quart. Journ. Geol. Soc." Volume II., 1846, page 170.) In a paper just read an author (552/3. "On the Remarkable Fossil Trees lately discovered near St. Helen's." By E.W. Binney. "Phil. Mag." Volume XXIV., page 165, 1844. On page 173 the author writes: "The Stigmaria or Sigillaria, whichever name is to be retained... was a tree that undoubtedly grew in water.") throws out the idea that the Sigillaria was an aquatic plant (552/4. See "Life and Letters," I., pages 356 et seq.)—I suppose a Cycad-Conifer with the habits of the mangrove. From simple geological reasoning I have for some time been led to suspect that the great (and great and difficult it is) problem of the Coal would be solved on the theory of the upright plants having been aquatic. But even on such, I presume improbable notion, there are, as it strikes me, immense difficulties, and none greater than the width of the coal-fields. On what kind of coast or land could the plants have lived? It is a grand problem, and I trust you will grapple with it. I shall like much to have some discussion with you. When will you come here again? I am very sorry to infer from your letter that your sister has been ill.

LETTER 553. TO J.D. HOOKER. [June 2nd, 1847.]

I received your letter the other day, full of curious facts, almost all new to me, on the coal-question. (553/1. Sir Joseph Hooker deals with the formation of coal in his classical paper "On the Vegetation of the Carboniferous Period, as compared with that of the Present Day." "Mem. Geol. Surv. Great Britain," Volume II., pt. ii., 1848.) I will bring your note to Oxford (553/2. The British Association met at Oxford in 1847.), and then we will talk it over. I feel pretty sure that some of your purely geological difficulties are easily solvable, and I can, I think, throw a very little light on the shell difficulty. Pray put no stress in your mind about the alternate, neatly divided, strata of sandstone and shale, etc. I feel the same sort of interest in the coal question as a man does watching two good players at play, he knowing little or nothing of the game. I confess your last letter (and this you will think very strange) has almost raised Binney's notion (an old, growing hobby-horse of mine) to the dignity of an hypothesis (553/3. Binney suggested that the Coal-plants grew in salt water. (See Letters 102, 552.) Recent investigations have shown that several of the plants of the Coal period possessed certain anatomical peculiarities, which indicate xerophytic characteristics, and lend support to the view that some at least of the plants grew in seashore swamps.), though very far yet below the promotion of being properly called a theory.

I will bring the remainder of my species-sketch to Oxford to go over your remarks. I have lately been getting a good many rich facts. I saw the poor old Dean of Manchester (553/4. Dean Herbert.) on Friday, and he received me very kindly. He looked dreadfully ill, and about an hour afterwards died! I am most sincerely sorry for it.

LETTER 554. TO J.D. HOOKER. [May 12th, 1847.]

I cannot resist thanking you for your most kind note. Pray do not think that I was annoyed by your letter. I perceived that you had been thinking with animation, and accordingly expressed yourself strongly, and so I understood it. Forefend me from a man who weighs every expression with Scotch prudence. I heartily wish you all success in your noble problem, and I shall be very curious to have some talk with you and hear your ultimatum. (554/1. The above paragraph was published in "Life and Letters," I., page 359.) I do really think, after Binney's pamphlet (554/2. "On the Origin of Coal," "Mem. Lit. Phil. Soc." Manchester Volume VIII., page 148, 1848.), it will be worth your while to array your facts and ideas against an aquatic origin of the coal, though I do not know whether you object to freshwater. I am sure I have read somewhere of the cones of Lepidodendron being found round the stump of a tree, or am I confusing something else? How interesting all rooted—better, it seems from what you say, than upright—specimens become.

I wish Ehrenberg would undertake a microscopical hunt for infusoria in the underclay and shales; it might reveal something. Would a comparison of the ashes of terrestrial peat and coal give any clue? (554/3. In an article by M. F. Rigaud on "La Formation de la Houille," published in the "Revue Scientifique," Volume II., page 385, 1894, the author lays stress on the absence of certain elements in the ash of coals, which ought to be present, on the assumption that the carbon has been derived from plant tissues. If coal consists of altered vegetable debris, we ought to find a certain amount of alkalies and phosphoric acid in its ash. Had such substances ever been present, it is difficult to understand how they could all have been removed by the solvent action of water. (Rigaud's views are given at greater length in an article on the "Structure and Formation of Coal," "Science Progress," Volume II., pages 355 and 431, 1895.)) Peat ashes are good manure, and coal ashes, except mechanically, I believe are of little use. Does this indicate that the soluble salts have been washed out? i.e., if they are NOT present. I go up to Geological Council to-day—so farewell.

(554/4. In a letter to Sir Joseph Hooker, October 6th, 1847, Mr. Darwin, in referring to the origin of Coal, wrote: "...I sometimes think it could not have been formed at all. Old Sir Anthony Carlisle once said to me gravely that he supposed Megatherium and such cattle were just sent down from heaven to see whether the earth would support them, and I suppose the coal was rained down to puzzle mortals. You must work the coal well in India.")

LETTER 555. TO J.D. HOOKER. Down, May 22nd, 1860.

Lyell tells me that Binney has published in Proceedings of Manchester Society a paper trying to show that Coal plants must have grown in very marine marshes. (555/1. "On the Origin of Coal," by E.W. Binney, "Mem. Lit. Phil. Soc. Manchester," Volume VIII., 1848, page 148. Binney examines the evidence on which dry land has been inferred to exist during the formation of the Coal Measures, and comes to the conclusion that the land was covered by water, confirming Brongniart's opinion that Sigillaria was an aquatic plant. He believes the Sigillaria "grew in water, on the deposits where it is now discovered, and that it is the plant which in a great measure contributed to the formation of our valuable beds of coal." (Loc. cit., page 193.)) Do you remember how savage you were long years ago at my broaching such a conjecture?

LETTER 556. TO L. HORNER. Down [1846?].

I am truly pleased at your approval of my book (556/1. "Geological Observations on South America," London, 1846.): it was very kind of you taking the trouble to tell me so. I long hesitated whether I would publish it or not, and now that I have done so at a good cost of trouble, it is indeed highly satisfactory to think that my labour has not been quite thrown away.

I entirely acquiesce in your criticism on my calling the Pampean formation "recent" (556/2. "We must, therefore, conclude that the Pampean formation belongs, in the ordinary geological sense of the word, to the Recent Period." ("Geol. Obs." page 101).); Pleistocene would have been far better. I object, however, altogether on principle (whether I have always followed my principle is another question) to designate any epoch after man. It breaks through all principles of classification to take one mammifer as an epoch. And this is presupposing we know something of the introduction of man: how few years ago all beds earlier than the Pleistocene were characterised as being before the monkey epoch. It appears to me that it may often be convenient to speak of an Historical or Human deposit in the same way as we speak of an Elephant bed, but that to apply it to an epoch is unsound.

I have expressed myself very ill, and I am not very sure that my notions are very clear on this subject, except that I know that I have often been made wroth (even by Lyell) at the confidence with which people speak of the introduction of man, as if they had seen him walk on the stage, and as if, in a geological chronological sense, it was more important than the entry of any other mammifer.

You ask me to do a most puzzling thing, to point out what is newest in my volume, and I found myself incapable of doing almost the same for Lyell. My mind goes from point to point without deciding: what has interested oneself or given most trouble is, perhaps quite falsely, thought newest. The elevation of the land is perhaps more carefully treated than any other subject, but it cannot, of course, be called new. I have made out a sort of index, which will not take you a couple of minutes to skim over, and then you will perhaps judge what seems newest. The summary at the end of the book would also serve same purpose.

I do not know where E. de B. [Elie de Beaumont] has lately put forth on the recent elevation of the Cordillera. He "rapported" favourably on d'Orbigny, who in late times fires off a most Royal salute; every volcano bursting forth in the Andes at the same time with their elevation, the debacle thus caused depositing all the Pampean mud and all the Patagonian shingle! Is not this making Geology nice and simple for beginners?

We have been very sorry to hear of Bunbury's severe illness; I believe the measles are often dangerous to grown-up people. I am very glad that your last account was so much better.

I am astonished that you should have had the courage to go right through my book. It is quite obvious that most geologists find it far easier to write than to read a book.

Chapter I. and II.—Elevation of the land: equability on E. coast as shown by terraces, page 19; length on W. coast, page 53; height at Valparaiso, page 32; number of periods of rest at Coquimbo, page 49; elevation within Human period near Lima greater than elsewhere observed; the discussion (page 41) on non-horizontality of terraces perhaps one of newest features—on formation of terraces rather newish.

Chapter III., page 65.—Argument of horizontal elevation of Cordillera I believe new. I think the connection (page 54) between earthquake [shocks] and insensible rising important.

Chapter IV.—The strangeness of the (Eocene) mammifers, co-existing with recent shells.

Chapter V.—Curious pumiceous infusorial mudstone (page 118) of Patagonia; climate of old Tertiary period, page 134. The subject which has been most fertile in my mind is the discussion from page 135 to end of chapter on the accumulation of fossiliferous deposits. (556/3. The last section of Chapter V. treats of "the Absence of extensive modern Conchiferous Deposits in South America; and on the contemporaneousness of the older Tertiary Deposits at distant points being due to contemporaneous movements of subsidence." Darwin expresses the view that "the earth's surface oscillates up and down; and...during the elevatory movements there is but a small chance of durable fossiliferous deposits accumulating" (loc. cit., page 139).)

Chapter VI.—Perhaps some facts on metamorphism, but chiefly on the layers in mica-slate, etc., being analogous to cleavage.

Chapter VII.—The grand up-and-down movements (and vertical silicified trees) in the Cordillera: see summary, page 204 and page 240. Origin of the Claystone porphyry formation, page 170.

Chapter VIII., page 224.—Mixture of Cretaceous and Oolitic forms (page 226)—great subsidence. I think (page 232) there is some novelty in discussion on axes of eruption and injection. (page 247) Continuous volcanic action in the Cordillera. I think the concluding summary (page 237) would show what are the most salient features in the book.

LETTER 557. TO C. LYELL. Shrewsbury [August 10th, 1846].

I was delighted to receive your letter, which was forwarded here to me. I am very glad to hear about the new edition of the "Principles," (557/1. The seventh edition of the "Principles of Geology" was published in 1847.), and I most heartily hope you may live to bring out half a dozen more editions. There would not have been such books as d'Orbigny's S. American Geology (557/2. "Voyage dans l'Amerique meridionale execute pendant les Annees 1826-37." 6 volumes, Paris, 1835-43.) published, if there had been seven editions of the "Principles" distributed in France. I am rather sorry about the small type; but the first edition, my old true love, which I never deserted for the later editions, was also in small type. I much fear I shall not be able to give any assistance to Book III. (557/3. This refers to Book III. of the "Principles"—"Changes of the Organic World now in Progress.") I think I formerly gave my few criticisms, but I will read it over again very soon (though I am striving to finish my S. American Geology (557/4. "Geological Observations on South America" was published in 1846.)) and see whether I can give you any references. I have been thinking over the subject, and can remember no one book of consequence, as all my materials (which are in an absolute chaos on separate bits of paper) have been picked out of books not directly treating of the subjects you have discussed, and which I hope some day to attempt; thus Hooker's "Antarctic Flora" I have found eminently useful (557/5. "Botany of the Antarctic Voyage of H.M.S. 'Erebus' and 'Terror' in the Years 1839-43." I., "Flora Antarctica." 2 volumes, London, 1844-47.), and yet I declare I do not know what precise facts I could refer you to. Bronn's "Geschichte" (557/6. "Naturgeschichte der drei Reiche." H.E. Bronn, Stuttgart, 1834-49.) which you once borrowed) is the only systematic book I have met with on such subjects; and there are no general views in such parts as I have read, but an immense accumulation of references, very useful to follow up, but not credible in themselves: thus he gives hybrids from ducks and fowls just as readily as between fowls and pheasants! You can have it again if you like. I have no doubt Forbes' essay, which is, I suppose, now fairly out, will be very good under geographical head. (557/7. "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, especially during the Epoch of the Northern Drift," by E. Forbes. "Memoirs of Geological Survey," Volume I., page 336, 1846.) Kolreuter's German book is excellent on hybrids, but it will cost you a good deal of time to work out any conclusion from his numerous details. (557/8. Joseph Gottlieb Kolreuter's "Vorlaufige Nachricht von eininigen das Geschlecht der Pflanzen betreffenden Versuchen und Beobachtungen." Leipzig, 1761.) With respect to variation I have found nothing—but minute details scattered over scores of volumes. But I will look over Book III. again. What a quantity of work you have in hand! I almost wish you could have finished America, and thus have allowed yourself rather more time for the old "Principles"; and I am quite surprised that you could possibly have worked your own new matter in within six weeks. Your intention of being in Southampton will much strengthen mine, and I shall be very glad to hear some of your American Geology news.

LETTER 558. TO L. HORNER. Down, Sunday [January 1847].

Your most agreeable praise of my book is enough to turn my head; I am really surprised at it, but shall swallow it with very much gusto... (558/1. "Geological Observations in S. America," London, 1846.)

E. de Beaumont measured the inclination with a sextant and artificial horizon, just as you take the height of the sun for latitude.

With respect to my Journal, I think the sketches in the second edition (558/2. "Journal of Researches into the Natural History and Geology of the Countries visited during the Voyage of H.M.S. 'Beagle.'" Edition II. London, 1845.) are pretty accurate; but in the first they are not so, for I foolishly trusted to my memory, and was much annoyed to find how hasty and inaccurate many of my remarks were, when I went over my huge pile of descriptions of each locality.

If ever you meet anyone circumstanced as I was, advise him not, on any account, to give any sketches until his materials are fully worked out.

What labour you must be undergoing now; I have wondered at your patience in having written to me two such long notes. How glad Mrs. Horner will be when your address is completed. (558/3. Anniversary Address of the President ("Quart. Journ. Geol. Soc." Volume III., page xxii, 1847).) I must say that I am much pleased that you will notice my volume in your address, for former Presidents took no notice of my two former volumes.

I am exceedingly glad that Bunbury is going on well.

LETTER 559. TO C. LYELL. Down, July 3rd [1849].

I don't know when I have read a book so interesting (559/1. "A Second Visit to the United States of North America." 2 volumes, London, 1849.); some of your stories are very rich. You ought to be made Minister of Public Education—not but what I should think even that beneath the author of the old "Principles." Your book must, I should think, do a great deal of good and set people thinking. I quite agree with the "Athenaeum" that you have shown how a man of science can bring his powers of observation to social subjects. (559/2. "Sir Charles Lyell, besides the feelings of a gentleman, seems to carry with him the best habits of scientific observation into other strata than those of clay, into other 'formations' than those of rock or river-margin." "The Athenaeum," June 23rd, 1849, page 640.) You have made H. Wedgwood, heart and soul, an American; he wishes the States would annex us, and was all day marvelling how anyone who could pay his passage money was so foolish as to remain here.

LETTER 560. TO C. LYELL. Down, [December, 1849].

(560/1. In this letter Darwin criticises Dana's statements in his volume on "Geology," forming Volume X. of the "Wilkes Exploring Expedition," 1849.)

...Dana is dreadfully hypothetical in many parts, and often as "d—d cocked sure" as Macaulay. He writes however so lucidly that he is very persuasive. I am more struck with his remarks on denudation than you seem to be. I came to exactly the same conclusion in Tahiti, that the wonderful valleys there (on the opposite extreme of the scale of wonder [to] the valleys of New South Wales) were formed exclusively by fresh water. He underrates the power of sea, no doubt, but read his remarks on valleys in the Sandwich group. I came to the conclusion in S. America (page 67) that the main effect of fresh water is to deepen valleys, and sea to widen them; I now rather doubt whether in a valley or fiord...the sea would deepen the rock at its head during the elevation of the land. I should like to tour on the W. coast of Scotland, and attend to this. I forget how far generally the shores of fiords (not straits) are cliff-formed. It is a most interesting subject.

I return once again to Coral. I find he does not differ so much in detail with me regarding areas of subsidence; his map is coloured on some quite unintelligible principle, and he deduces subsidence from the vaguest grounds, such as that the N. Marianne Islands must have subsided because they are small, though long in volcanic action: and that the Marquesas subsided because they are penetrated by deep bays, etc., etc. I utterly disbelieve his statements that most of the atolls have been lately raised a foot or two. He does not condescend to notice my explanation for such appearances. He misrepresents me also when he states that I deduce, without restriction, elevation from all fringing reefs, and even from islands without any reefs! If his facts are true, it is very curious that the atolls decrease in size in approaching the vast open ocean S. of the Sandwich Islands. Dana puts me in a passion several times by disputing my conclusions without condescending to allude to my reasons; thus, regarding S. Lorenzo elevation, he is pleased to speak of my "characteristic accuracy" (560/2. Dana's "Geology" (Wilkes expedition), page 590.), and then gives difficulties (as if his own) when they are stated by me, and I believe explained by me—whereas he only alludes to a few of the facts. So in Australian valleys, he does not allude to my several reasons. But I am forgetting myself and running on about what can only interest myself. He strikes me as a very clever fellow; I wish he was not quite so grand a generaliser. I see little of interest except on volcanic action and denudation, and here and there scattered remarks; some of the later chapters are very bald.

LETTER 561. TO J.D. DANA. Down, December 5th, 1849.

I have not for some years been so much pleased as I have just been by reading your most able discussion on coral reefs. I thank you most sincerely for the very honourable mention you make of me. (561/1. "United States Exploring Expedition during the Years 1839-42 under the Command of Charles Wilkes, U.S.N." Volume X., "Geology," by J.D. Dana, 1849.) This day I heard that the atlas has arrived, and this completes your munificent present to me. I have not yet come to the chapter on subsidence, and in that I fancy we shall disagree, but in the descriptive part our agreement has been eminently satisfactory to me, and far more than I ever ventured to anticipate. I consider that now the subsidence theory is established. I have read about half through the descriptive part of the "Volcanic Geology" (561/2. Part of Dana's "Geology" is devoted to volcanic action.) (last night I ascended the peaks of Tahiti with you, and what I saw in my short excursion was most vividly brought before me by your descriptions), and have been most deeply interested by it. Your observations on the Sandwich craters strike me as the most important and original of any that I have read for a long time. Now that I have read yours, I believe I saw at the Galapagos, at a distance, instances of those most curious fissures of eruption. There are many points of resemblance between the Galapagos and Sandwich Islands (even to the shape of the mound-like hills)—viz., in the liquidity of the lavas, absence of scoriae, and tuff-craters. Many of your scattered remarks on denudation have particularly interested me; but I see that you attribute less to sea and more to running water than I have been accustomed to do. After your remarks in your last very kind letter I could not help skipping on to the Australian valleys (561/3. Ibid., pages 526 et seq.: "The Formation of Valleys, etc., in New South Wales."), on which your remarks strike me as exceedingly ingenious and novel, but they have not converted me. I cannot conceive how the great lateral bays could have been scooped out, and their sides rendered precipitous by running water. I shall go on and read every word of your excellent volume.

If you look over my "Geological Instructions" you will be amused to see that I urge attention to several points which you have elaborately discussed. (561/4. "A Manual of Scientific Enquiry, prepared for the use of Her Majesty's Navy, and adapted for Travellers in General." Edited by Sir John F.W. Herschel, Bart. London, 1849 (Section VI., "Geology." By Charles Darwin).) I lately read a paper of yours on Chambers' book, and was interested by it. I really believe the facts of the order described by Chambers, in S. America, which I have described in my Geolog. volume. This leads me to ask you (as I cannot doubt that you will have much geological weight in N. America) to look to a discussion at page 135 in that volume on the importance of subsidence to the formation of deposits, which are to last to a distant age. This view strikes me as of some importance.

When I meet a very good-natured man I have that degree of badness of disposition in me that I always endeavour to take advantage of him; therefore I am going to mention some desiderata, which if you can supply I shall be very grateful, but if not no answer will be required.

Thank you for your "Conspectus Crust.," but I am sorry to say I am not worthy of it, though I have always thought the Crustacea a beautiful subject. (561/5. "Conspectus Crustaceorum in orbis terrarum circumnavigatione, C. Wilkes duce, collectorum." Cambridge (U.S.A.), 1847.)

LETTER 562. TO C. LYELL. [Down, March 9th, 1850.]

I am uncommonly much obliged to you for your address, which I had not expected to see so soon, and which I have read with great interest. (562/1. Anniversary Address of the President, "Quart. Journ. Geol. Soc." Volume VI., page 32, 1850.) I do not know whether you spent much time over it, but it strikes me as extra well arranged and written—done in the most artistic manner, to use an expression which I particularly hate. Though I am necessarily pretty well familiar with your ideas from your conversation and books, yet the whole had an original freshness to me. I am glad that you broke through the routine of the President's addresses, but I should be sorry if others did. Your criticisms on Murchison were to me, and I think would be to many, particularly acceptable. (562/2. In a paper "On the Geological Structure of the Alps, etc." ("Quart. Journ. Geol. Soc." Volume V., page 157, 1849) Murchison expressed his belief that the apparent inversion of certain Tertiary strata along the flanks of the Alps afforded "a clear demonstration of a sudden operation or catastrophe." It is this view of paroxysmal energy that Lyell criticises in the address.) Capital, that metaphor of the clock. (562/3. "In a word, the movement of the inorganic world is obvious and palpable, and might be likened to the minute-hand of a clock, the progress of which can be seen and heard, whereas the fluctuations of the living creation are nearly invisible, and resemble the motion of the hour-hand of a timepiece" (loc. cit., page xlvi).) I shall next February be much interested by seeing your hour-hand of the organic world going.

Many thanks for your kindness in taking the trouble to tell me of the anniversary dinner. What a compliment that was which Lord Mahon paid me! I never had so great a one. He must be as charming a man as his wife is a woman, though I was formerly blind to his merit. Bunsen's speech must have been very interesting and very useful, if any orthodox clergyman were present. Your metaphor of the pebbles of pre-existing languages reminds me that I heard Sir J. Herschel at the Cape say how he wished some one would treat language as you had Geology, and study the existing causes of change, and apply the deduction to old languages.

We are all pretty flourishing here, though I have been retrograding a little, and I think I stand excitement and fatigue hardly better than in old days, and this keeps me from coming to London. My cirripedial task is an eternal one; I make no perceptible progress. I am sure that they belong to the hour-hand, and I groan under my task.

LETTER 563. C. LYELL TO CHARLES DARWIN. April 23rd, 1855.

I have seen a good deal of French geologists and palaeontologists lately, and there are many whom I should like to put on the R.S. Foreign List, such as D'Archiac, Prevost, and others. But the man who has made the greatest sacrifices and produced the greatest results, who has, in fact, added a new period to the calendar, is Barrande.

The importance of his discoveries as they stand before the public fully justify your choice of him; but what is unpublished, and which I have seen, is, if possible, still more surprising. Thirty genera of gasteropods (150 species) and 150 species of lamellibranchiate bivalves in the Silurian! All obtained by quarries opened solely by him for fossils. A man of very moderate fortune spending nearly all his capital on geology, and with success.

E. Forbes' polarity doctrines are nearly overturned by the unpublished discoveries of Barrande. (563/1. See note, Letter 41, Volume I.)

I have called Barrande's new period Cambrian (see "Manual," 5th edition), and you will see why. I could not name it Protozoic, but had Barrande called it Bohemian, I must have adopted that name. All the French will rejoice if you confer an honour on Barrande. Dana is well worthy of being a foreign member.

Should you succeed in making Barrande F.R.S., send me word.

LETTER 564. TO J.D. HOOKER. June 5th [1857].

(564/1. The following, which bears on the subject of medals, forms part of the long letter printed in the "Life and Letters," II., page 100.)

I do not quite agree with your estimate of Richardson's merits. Do, I beg you (whenever you quietly see), talk with Lyell on Prestwich: if he agrees with Hopkins, I am silenced; but as yet I must look at the correlation of the Tertiaries as one of the highest and most frightfully difficult tasks a man could set himself, and excellent work, as I believe, P. has done. (564/2. Prof. Prestwich had published numerous papers dealing with Tertiary Geology before 1857. The contributions referred to are probably those "On the Correlation of the Lower Tertiaries of England with those of France and Belgium," "Quart. Journ. Geol. Soc." Volume X., 1854, page 454; and "On the Correlation of the Middle Eocene Tertiaries of England, France, and Belgium," ibid., XII., 1856, page 390.) I confess I do not value Hopkins' opinion on such a point. I confess I have never thought, as you show ought to be done, on the future. I quite agree, under all circumstances, with the propriety of Lindley. How strange no new geologists are coming forward! Are there not lots of good young chemists and astronomers or physicists? Fitton is the only old geologist left who has done good work, except Sedgwick. Have you thought of him? He would be a brilliant companion for Lindley. Only it would never do to give Lyell a Copley and Sedgwick a Royal in the same year. It seems wrong that there should be three Natural Science medals in the same year. Lindley, Sedgwick, and Bunsen sounds well, and Lyell next year for the Copley. (564/3. In 1857 a Royal medal was awarded to John Lindley; Lyell received the Copley in 1858, and Bunsen in 1860.) You will see that I am speculating as a mere idle amateur.

LETTER 565. TO S.P. WOODWARD. Down, May 27th [1856].

I am very much obliged to you for having taken the trouble to answer my query so fully. I can now be at rest, for from what you say and from what little I remember Forbes said, my point is unanswerable. The case of Terebratula is to the point as far as it goes, and is negative. I have already attempted to get a solution through geographical distribution by Dr. Hooker's means, and he finds that the same genera which have very variable species in Europe have other very variable species elsewhere. This seems the general rule, but with some few exceptions. I see from the several reasons which you assign, that there is no hope of comparing the same genus at two different periods, and seeing whether the tendency to vary is greater at one period in such genus than at another period. The variability of certain genera or groups of species strikes me as a very odd fact. (565/1. The late Dr. Neumayr has dealt, to some extent, with this subject in "Die Stamme des Thierreichs," Volume I., Wien, 1889.)

I shall have no points, as far as I can remember, to suggest for your reconsideration, but only some on which I shall have to beg for a little further information. However, I feel inclined very much to dispute your doctrine of islands being generally ancient in comparison, I presume, with continents. I imagine you think that islands are generally remnants of old continents, a doctrine which I feel strongly disposed to doubt. I believe them generally rising points; you, it seems, think them sinking points.

LETTER 566. TO T.H. HUXLEY. Down, April 14th [1860].

Many thanks for your kind and pleasant letter. I have been much interested by "Deep-sea Soundings,", and will return it by this post, or as soon as I have copied a few sentences. (566/1. Specimens of the mud dredged by H.M.S. "Cyclops" were sent to Huxley for examination, who gave a brief account of them in Appendix A of Capt. Dayman's Report, 1858, under the title "Deep-sea Soundings in the North Atlantic.") I think you said that some one was investigating the soundings. I earnestly hope that you will ask the some one to carefully observe whether any considerable number of the calcareous organisms are more or less friable, or corroded, or scaling; so that one might form some crude notion whether the deposition is so rapid that the foraminifera are preserved from decay and thus are forming strata at this profound depth. This is a subject which seems to me to have been much neglected in examining soundings.

Bronn has sent me two copies of his Morphologische Studien uber die Gestaltungsgesetze." (H.G. Bronn, "Morphologische Studien uber die Gestaltungsgesetze der Naturkorper uberhaupt und der organischen insbesondere": Leipzig, 1858.) It looks elementary. If you will write you shall have the copy; if not I will give it to the Linnean Library.

I quite agree with the letter from Lyell that your extinguished theologians lying about the cradle of each new science, etc., etc., is splendid. (566/2. "Darwiniana, Collected Essays," Volume II., page 52.)

LETTER 567. TO T.H. HUXLEY. May 10th [1862 or later].

I have been in London, which has prevented my writing sooner. I am very sorry to hear that you have been ill: if influenza, I can believe in any degree of prostration of strength; if from over-work, for God's sake do not be rash and foolish. You ask for criticisms; I have none to give, only impressions. I fully agree with your "skimming-of-pot theory," and very well you have put it. With respect [to] contemporaneity I nearly agree with you, and if you will look to the d—d book, 3rd edition, page 349 you will find nearly similar remarks. (567/1. "When the marine forms are spoken of as having changed simultaneously throughout the world, it must not be supposed that this expression relates to the same year, or to the same century, or even that it has a very strict geological sense; for if all the marine animals now living in Europe, and all those that lived in Europe during the Pleistocene period (a very remote period as measured by years, including the whole Glacial epoch), were compared with those now existing in South America or in Australia, the most skilful naturalist would hardly be able to say whether the present or the Pleistocene inhabitants of Europe resembled most closely those of the Southern hemisphere." "Origin," Edition VI., page 298. The passage in Edition III., page 350, is substantially the same.) But at page 22 of your Address, in my opinion you put your ideas too far. (567/2. Anniversary Address to the Geological Society of London ("Quart. Journ. Geol. Soc." Volume XVIII., page xl, 1862). As an illustration of the misleading use of the term "contemporaneous" as employed by geologists, Huxley gives the following illustration: "Now suppose that, a million or two of years hence, when Britain has made another dip beneath the sea and has come up again, some geologist applies this doctrine [i.e., the doctrine of the Contemporaneity of the European and of the North American Silurians: proof of contemporaneity is considered to be established by the occurrence of 60 per cent. of species in common], in comparing the strata laid bare by the upheaval of the bottom, say, of St. George's Channel with what may then remain of the Suffolk Crag. Reasoning in the same way, he will at once decide the Suffolk Crag and the St. George's Channel beds to be contemporaneous; although we happen to know that a vast period...of time...separates the two" (loc. cit., page xlv). This address is republished in the "Collected Essays," Volume VIII.; the above passage is at page 284.) I cannot think that future geologists would rank the Suffolk and St. George's strata as contemporaneous, but as successive sub-stages; they rank N. America and British stages as contemporaneous, notwithstanding a percentage of different species (which they, I presume, would account for by geographical difference) owing to the parallel succession of the forms in both countries. For terrestrial productions I grant that great errors may creep in (567/3. Darwin supposes that terrestrial productions have probably not changed to the same extent as marine organisms. "If the Megatherium, Mylodon...had been brought to Europe from La Plata, without any information in regard to their geological position, no one would have suspected that they had co-existed with sea shells all still living" ("Origin," Edition VI., page 298).); but I should require strong evidence before believing that, in countries at all well-known, so-called Silurian, Devonian, and Carboniferous strata could be contemporaneous. You seem to me on the third point, viz., on non-advancement of organisation, to have made a very strong case. I have not knowledge or presumption enough to criticise what you say. I have said what I could at page 363 of "Origin." It seems to me that the whole case may be looked at from several points of view. I can add only one miserable little special case of advancement in cirripedes. The suspicion crosses me that if you endeavoured your best you would say more on the other side. Do you know well Bronn in his last Entwickelung (or some such word) on this subject? it seemed to me very well done. (567/4. Probably "Untersuchungen uber die Entwickelungsgesetze der organischen Welt wahrend der Bildungszeit unserer Erdoberflache," Stuttgart, 1858. Translated by W.S. Dallas in the "Ann. and Mag. Nat. Hist." Volume IV., page 81.) I hope before you publish again you will read him again, to consider the case as if you were a judge in a court of appeal; it is a very important subject. I can say nothing against your side, but I have an "inner consciousness" (a highly philosophical style of arguing!) that something could be said against you; for I cannot help hoping that you are not quite as right as you seem to be. Finally, I cannot tell why, but when I finished your Address I felt convinced that many would infer that you were dead against change of species, but I clearly saw that you were not. I am not very well, so good-night, and excuse this horrid letter.

LETTER 568. TO J.D. HOOKER. Down, June 30th [1866].

I have heard from Sulivan (who, poor fellow, gives a very bad account of his own health) about the fossils (568/1. In a letter to Huxley (June 4th, 1866) Darwin wrote: "Admiral Sulivan several years ago discovered an astonishingly rich accumulation of fossil bones not far from the Straits [of Magellan]...During many years it has seemed to me extremely desirable that these should be collected; and here is an excellent opportunity.")... The place is Gallegos, on the S. coast of Patagonia. Sulivan says that in the course of two or three days all the boats in the ship could be filled twice over; but to get good specimens out of the hardish rock two or three weeks would be requisite. It would be a grand haul for Palaeontology. I have been thinking over your lecture. (568/2. A lecture on "Insular Floras" given at the British Association meeting at Nottingham, August 27th, 1866, published in the "Gard. Chron." 1867.) Will it not be possible to give enlarged drawings of some leading forms of trees? You will, of course, have a large map, and George tells me that he saw at Sir H. James', at Southampton, a map of the world on a new principle, as seen from within, so that almost 4/5ths of the globe was shown at once on a large scale. Would it not be worth while to borrow one of these from Sir H. James as a curiosity to hang up?

Remember you are to come here before Nottingham. I have almost finished the last number of H. Spencer, and am astonished at its prodigality of original thought. But the reflection constantly recurred to me that each suggestion, to be of real value to science, would require years of work. It is also very unsatisfactory, the impossibility of conjecturing where direct action of external circumstances begins and ends—as he candidly owns in discussing the production of woody tissue in the trunks of trees on the one hand, and on the other in spines and the shells of nuts. I shall like to hear what you think of this number when we meet.

LETTER 569. TO A. GAUDRY. Down, November 17th, 1868.

On my return home after a short absence I found your note of Nov. 9th, and your magnificent work on the fossil animals of Attica. (569/1. The "Geologie de l'Attique," 2 volumes 4to, 1862-7, is the only work of Gaudry's of this date in Mr. Darwin's library.) I assure you that I feel very grateful for your generosity, and for the honour which you have thus conferred on me. I know well, from what I have already read of extracts, that I shall find your work a perfect mine of wealth. One long passage which Sir C. Lyell quotes from you in the 10th and last edition of the "Principles of Geology" is one of the most striking which I have ever read on the affiliation of species. (569/2. The quotation in Lyell's "Principles," Edition X., Volume II., page 484, is from M. Gaudry's "Animaux Fossiles de Pikermi," 1866, page 34:—

"In how different a light does the question of the nature of species now present itself to us from that in which it appeared only twenty years ago, before we had studied the fossil remains of Greece and the allied forms of other countries. How clearly do these fossil relics point to the idea that species, genera, families, and orders now so distinct have had common ancestors. The more we advance and fill up the gaps, the more we feel persuaded that the remaining voids exist rather in our knowledge than in nature. A few blows of the pickaxe at the foot of the Pyrenees, of the Himalaya, of Mount Pentelicus in Greece, a few diggings in the sandpits of Eppelsheim, or in the Mauvaises Terres of Nebraska, have revealed to us the closest connecting links between forms which seemed before so widely separated. How much closer will these links be drawn when Palaeontology shall have escaped from its cradle!")

LETTER 570. A. SEDGWICK TO CHARLES DARWIN.

(570/1. In May, 1870, Darwin "went to the Bull Hotel, Cambridge, to see the boys, and for a little rest and enjoyment." (570/2. See "Life and Letters," III., 125.) The following letter was received after his return to Down.)

Trinity College, Cambridge, May 30th, 1870.

My dear Darwin,

Your very kind letter surprised me. Not that I was surprised at the pleasant and very welcome feeling with which it was written. But I could not make out what I had done to deserve the praise of "extraordinary kindness to yourself and family." I would most willingly have done my best to promote the objects of your visit, but you gave me no opportunity of doing so. I was truly grieved to find that my joy at seeing you again was almost too robust for your state of nerves, and that my society, after a little while, became oppressive to you. But I do trust that your Cambridge visit has done you no constitutional harm; nay, rather that it has done you some good. I only speak honest truth when I say that I was overflowing with joy when I saw you, and saw you in the midst of a dear family party, and solaced at every turn by the loving care of a dear wife and daughters. How different from my position—that of a very old man, living in cheerless solitude! May god help and cheer you all with the comfort of hopeful hearts—you and your wife, and your sons and daughters!

You were talking about my style of writing,—I send you my last specimen, and it will probably continue to be my last. It is the continuation of a former pamphlet of which I have not one spare copy. I do not ask you to read it. It is addressed to the old people in my native Dale of Dent, on the outskirts of Westmorland. While standing at the door of the old vicarage, I can see down the valley the Lake mountains—Hill Bell at the head of Windermere, about twenty miles off. On Thursday next (D.V.) I am to start for Dent, which I have not visited for full two years. Two years ago I could walk three or four miles with comfort. Now, alas! I can only hobble about on my stick.

I remain your true-hearted old friend A. Sedgwick.

LETTER 571. TO C. LYELL. Down, September 3rd [1874].

Many thanks for your very kind and interesting letter. I was glad to hear at Southampton from Miss Heathcote a good account of your health and strength.

With respect to the great subject to which you refer in your P.S., I always try to banish it from my mind as insoluble; but if I were circumstanced as you are, no doubt it would recur in the dead of the night with painful force. Many persons seem to make themselves quite easy about immortality (571/1. See "Life and Letters," I., page 312.) and the existence of a personal God, by intuition; and I suppose that I must differ from such persons, for I do not feel any innate conviction on any such points.

We returned home about ten days ago from Southampton, and I enjoyed my holiday, which did me much good. But already I am much fatigued by microscope and experimental work with insect-eating plants.

When at Southampton I was greatly interested by looking at the odd gravel deposits near at hand, and speculating about their formation. You once told me something about them, but I forget what; and I think that Prestwich has written on the superficial deposits on the south coasts, and I must find out his paper and read it. (571/2. Prof. Prestwich contributed several papers to the Geological Society on the Superficial Deposits of the South of England.)

From what I have seen of Mr. Judd's papers I have thought that he would rank amongst the few leading British geologists.

LETTER 572. TO J.D. HOOKER.

(572/1. The following letter was written before Mr. Darwin knew that Sir Charles Lyell was to be buried in Westminster Abbey, a memorial which thoroughly satisfied him. See "Life and Letters," III., 197.)

Down, February 23rd, 1875.

I have just heard from Miss Buckley of Lyell's death. I have long felt opposed to the present rage for testimonials; but when I think how Lyell revolutionised Geology, and aided in the progress of so many other branches of science, I wish that something could be done in his honour. On the other hand it seems to me that a poor testimonial would be worse than none; and testimonials seem to succeed only when a man has been known and loved by many persons, as in the case of Falconer and Forbes. Now, I doubt whether of late years any large number of scientific men did feel much attachment towards Lyell; but on this head I am very ill fitted to judge. I should like to hear some time what you think, and if anything is proposed I should particularly wish to join in it. We have both lost as good and as true a friend as ever lived.

LETTER 573. TO J.D. HOOKER.

(573/1. This letter shows the difficulty which the inscription for Sir Charles Lyell's memorial gave his friends. The existing inscription is, "Charles Lyell...Author of 'The Principles of Geology'...Throughout a long and laborious life he sought the means of deciphering the fragmentary records of the Earth's history in the patient investigation of the present order of Nature, enlarging the boundaries of knowledge, and leaving on Scientific thought an enduring influence..."

Down, June 21st [1876].

I am sorry for you about the inscription, which has almost burst me. We think there are too many plurals in yours, and when read aloud it hisses like a goose. I think the omission of some words makes it much stronger. "World" (573/2. The suggested sentence runs: "he gave to the world the results of his labour, etc.") is much stronger and truer than "public." As Lyell wrote various other books and memoirs, I have some little doubt about the "Principles of Geology." People here do not like your "enduring value": it sounds almost an anticlimax. They do not much like my "last (or endure) as long as science lasts." If one reads a sentence often enough, it always becomes odious.

God help you.

LETTER 574. TO OSWALD HEER. Down, March 8th [1875].

I thank you for your very kind and deeply interesting letter of March 1st, received yesterday, and for the present of your work, which no doubt I shall soon receive from Dr. Hooker. (574/1. "Flora Fossilis Arctica," Volume III., 1874, sent by Prof. Heer through Sir Joseph Hooker.) The sudden appearance of so many Dicotyledons in the Upper Chalk appears to me a most perplexing phenomenon to all who believe in any form of evolution, especially to those who believe in extremely gradual evolution, to which view I know that you are strongly opposed. (574/2. The volume referred to contains a paper on the Cretaceous Flora of the Arctic Zone (Spitzbergen and Greenland), in which several dicotyledonous plants are described. In a letter written by Heer to Darwin the author speaks of a species of poplar which he describes as the oldest Dicotyledon so far recorded.) The presence of even one true Angiosperm in the Lower Chalk makes me inclined to conjecture that plants of this great division must have been largely developed in some isolated area, whence owing to geographical changes, they at last succeeded in escaping, and spread quickly over the world. (574/3. No satisfactory evidence has so far been brought forward of the occurrence of fossil Angiosperms in pre-Cretaceous rocks. The origin of the Monocotyledons and Dicotyledons remains one of the most difficult and attractive problems of Palaeobotany.) (574/4. See Letters 395, 398.) But I fully admit that this case is a great difficulty in the views which I hold. Many as have been the wonderful discoveries in Geology during the last half-century, I think none have exceeded in interest your results with respect to the plants which formerly existed in the Arctic regions. How I wish that similar collections could be made in the Southern hemisphere, for instance in Kerguelen's Land.

The death of Sir C. Lyell is a great loss to science, but I do not think to himself, for it was scarcely possible that he could have retained his mental powers, and he would have suffered dreadfully from their loss. The last time I saw him he was speaking with the most lively interest about his last visit to you, and I was grieved to hear from him a very poor account of your health. I have been working for some time on a special subject, namely insectivorous plants. I do not know whether the subject will interest you, but when my book is published I will have the pleasure of sending you a copy.

I am very much obliged for your photograph, and enclose one of myself.

LETTER 574*. TO S.B.J. SKERTCHLY. March 2nd, 1878.

It is the greatest possible satisfaction to a man nearly at the close of his career to believe that he has aided or stimulated an able and energetic fellow-worker in the noble cause of science. Therefore your letter has deeply gratified me. I am writing this away from home, as my health failed, and I was forced to rest; and this will account for the delay in answering your letter. No doubt on my return home I shall find the memoir which you have kindly sent me. I shall read it with much interest, as I have heard something of your work from Prof. Geikie, and have read his admirable "Ice Age." (574/5. "The Great Ice Age and its Relation to the Antiquity of Man": London, 1874. By James Geikie.) I have noticed the criticisms on your work, but such opposition must be expected by every one who draws fine grand conclusions, and such assuredly are yours as abstracted in your letter. (574/6. Mr. S.B.J. Skertchly recorded "the discovery of palaeolithic flint implements, mammalian bones, and fresh-water shells in brick-earths below the Boulder-clay of East Anglia," in a letter published in the "Geol. Mag." Volume III., page 476, 1876. (See also "The Fenland, Past and Present." S.H. Miller and S.B.J. Skertchly, London, 1878.) The conclusions of Mr. Skertchly as to the pre-Glacial age of the flint implements were not accepted by some authorities. (See correspondence in "Nature," Volume XV., 1877, pages 141, 142.) We are indebted to Mr. Marr for calling our attention to Mr. Skertchly's discovery.) What magnificent progress Geology has made within my lifetime!

I shall have very great pleasure in sending you any of my books with my autograph, but I really do not know which to send. It will cost you only the trouble of a postcard to tell me which you would like, and it shall soon be sent. Forgive this untidy note, as it is rather an effort to write.

With all good wishes for your continued success in science and for your happiness...



CHAPTER 2.X.—BOTANY, 1843-1871.

2.X.I. Miscellaneous.—2.X.II. Melastomaceae.—2.X.III. Correspondence with John Scott.

2.X.I. MISCELLANEOUS, 1843-1862.

(PLATE: SIR JOSEPH HOOKER, 1897. From a Photograph by W.J. Hawker Wimborne. Walker & Cockerell, ph. sc.)

LETTER 575. TO WILLIAM JACKSON HOOKER. Down, March 12th [1843].

...When you next write to your son, will you please remember me kindly to him and give him my best thanks for his note? I had the pleasure yesterday of reading a letter from him to Mr. Lyell of Kinnordy, full of the most interesting details and descriptions, and written (if I may be permitted to make such a criticism) in a particularly agreeable style. It leads me anxiously to hope, even more than I did before, that he will publish some separate natural history journal, and not allow (if it can be avoided) his materials to be merged in another work. I am very glad to hear you talk of inducing your son to publish an Antarctic Flora. I have long felt much curiosity for some discussion on the general character of the flora of Tierra del Fuego, that part of the globe farthest removed in latitude from us. How interesting will be a strict comparison between the plants of these regions and of Scotland and Shetland. I am sure I may speak on the part of Prof. Henslow that all my collection (which gives a fair representation of the Alpine flora of Tierra del Fuego and of Southern Patagonia) will be joyfully laid at his disposal.

LETTER 576. TO JOHN LINDLEY. Down, Saturday [April 8th, 1843].

I take the liberty, at the suggestion of Dr. Royle, of forwarding to you a few seeds, which have been found under very singular circumstances. They have been sent to me by Mr. W. Kemp, of Galashiels, a (partially educated) man, of whose acuteness and accuracy of observation, from several communications on geological subjects, I have a VERY HIGH opinion. He found them in a layer under twenty-five feet thickness of white sand, which seems to have been deposited on the margins of an anciently existing lake. These seeds are not known to the provincial botanists of the district. He states that some of them germinated in eight days after being planted, and are now alive. Knowing the interest you took in some raspberry seeds, mentioned, I remember, in one of your works, I hope you will not think me troublesome in asking you to have these seeds carefully planted, and in begging you so far to oblige me as to take the trouble to inform me of the result. Dr. Daubeny has started for Spain, otherwise I would have sent him some. Mr. Kemp is anxious to publish an account of his discovery himself, so perhaps you will be so kind as to communicate the result to me, and not to any periodical. The chance, though appearing so impossible, of recovering a plant lost to any country if not to the world, appears to me so very interesting, that I hope you will think it worth while to have these seeds planted, and not returned to me.

LETTER 577. TO C. LYELL. [September, 1843.]

An interesting fact has lately, as it were, passed through my hands. A Mr. Kemp (almost a working man), who has written on "parallel roads," and has corresponded with me (577/1. In a letter to Henslow, Darwin wrote: "If he [Mr. Kemp] had not shown himself a most careful and ingenious observer, I should have thought nothing of the case."), sent me in the spring some seeds, with an account of the spot where they were found, namely, in a layer at the bottom of a deep sand pit, near Melrose, above the level of the river, and which sand pit he thinks must have been accumulated in a lake, when the whole features of the valleys were different, ages ago; since which whole barriers of rock, it appears, must have been worn down. These seeds germinated freely, and I sent some to the Horticultural Society, and Lindley writes to me that they turn out to be a common Rumex and a species of Atriplex, which neither he nor Henslow (as I have since heard) have ever seen, and certainly not a British plant! Does this not look like a vivification of a fossil seed? It is not surprising, I think, that seeds should last ten or twenty thousand [years], as they have lasted two or three [thousand years] in the Druidical mounds, and have germinated.

When not building, I have been working at my volume on the volcanic islands which we visited; it is almost ready for press...I hope you will read my volume, for, if you don't, I cannot think of anyone else who will! We have at last got our house and place tolerably comfortable, and I am well satisfied with our anchorage for life. What an autumn we have had: completely Chilian; here we have had not a drop of rain or a cloudy day for a month. I am positively tired of the fine weather, and long for the sight of mud almost as much as I did when in Peru.

(577/2. The vitality of seeds was a subject in which Darwin continued to take an interest. In July, 1855 ("Life and Letters," II., page 65), he wrote to Hooker: "A man told me the other day of, as I thought, a splendid instance—and splendid it was, for according to his evidence the seed came up alive out of the lower part of the London Clay! I disgusted him by telling him that palms ought to have come up."

In the "Gardeners' Chronicle," 1855, page 758, appeared a notice (half a column in length) by Darwin on the "Vitality of Seeds." The facts related refer to the "Sand-walk" at Down; the wood was planted in 1846 on a piece of pasture land laid down as grass in 1840. In 1855, on the soil being dug in several places, Charlock (Brassica sinapistrum) sprang up freely. The subject continued to interest him, and we find a note dated July 2nd, 1874, in which Darwin recorded that forty-six plants of Charlock sprang up in that year over a space (14 x 7 feet) which had been dug to a considerable depth. In the course of the article in the "Gardeners' Chronicle," Darwin remarks: "The power in seeds of retaining their vitality when buried in damp soil may well be an element in preserving the species, and therefore seeds may be specially endowed with this capacity; whereas the power of retaining vitality in a dry artificial condition must be an indirect, and in one sense accidental, quality in seeds of little or no use to the species."

The point of view expressed in the letter to Lyell above given is of interest in connection with the research of Horace Brown and F. Escombe (577/3. "Proc. Roy. Soc." Volume LXII., page 160.) on the remarkable power possessed by dry seeds of resistance to the temperature of liquid air. The point of the experiment is that life continues at a temperature "below that at which ordinary chemical reactions take place." A still more striking demonstration of the fact has been made by Thiselton-Dyer and Dewar who employed liquid hydrogen as a refrigerant. (577/4. Read before the British Association (Dover), 1899, and published in the "Comptes rendus," 1899, and in the "Proc. R. Soc." LXV., page 361, 1899.) The connection between these facts and the dormancy of buried seeds is only indirect; but inasmuch as the experiment proves the possibility of life surviving a period in which no ordinary chemical change occurs, it is clear that they help one to believe in greatly prolonged dormancy in conditions which tend to check metabolism. For a discussion of the bearing of their results on the life-problem, and for the literature of the subject, reference should be made to the paper by Brown and Escombe. See also C. de Candolle "On Latent Life in Seeds," "Brit. Assoc. Report," 1896, page 1023 and F. Escombe, "Science Progress," Volume I., N.S., page 585, 1897.)

LETTER 578. TO J.S. HENSLOW. Down, Saturday [November 5th, 1843].

I sent that weariful Atriplex to Babington, as I said I would, and he tells me that he has reared a facsimile by sowing the seeds of A. angustifolia in rich soil. He says he knows the A. hastata, and that it is very different. Until your last note I had not heard that Mr. Kemp's seeds had produced two Polygonums. He informs me he saw each plant bring up the husk of the individual seed which he planted. I believe myself in his accuracy, but I have written to advise him not to publish, for as he collected only two kinds of seeds—and from them two Polygomuns, two species or varieties of Atriplex and a Rumex have come up, any one would say (as you suggested) that more probably all the seeds were in the soil, than that seeds, which must have been buried for tens of thousands of years, should retain their vitality. If the Atriplex had turned out new, the evidence would indeed have been good. I regret this result of poor Mr. Kemp's seeds, especially as I believed, from his statements and the appearance of the seeds, that they did germinate, and I further have no doubt that their antiquity must be immense. I am sorry also for the trouble you have had. I heard the other day through a circuitous course how you are astonishing all the clodhoppers in your whole part of the county: and [what is] far more wonderful, as it was remarked to me, that you had not, in doing this, aroused the envy of all the good surrounding sleeping parsons. What good you must do to the present and all succeeding generations. (578/1. For an account of Professor Henslow's management of his parish of Hitcham see "Memoir of the Rev. John Stevens Henslow, M.A." by the Rev. Leonard Jenyns: 8vo, London, 1862.)

LETTER 579. TO J.D. HOOKER. Down, November 14th [1855].

You well know how credulous I am, and therefore you will not be surprised at my believing the Raspberry story (579/1. This probably refers to Lindley's story of the germination of raspberry seeds taken from a barrow 1600 years old.): a very similar case is on record in Germany—viz., seeds from a barrow; I have hardly zeal to translate it for the "Gardeners' Chronicle." (579/2. "Vitality of Seeds," "Gardeners' Chronicle," November 17th, 1855, page 758.) I do not go the whole hog—viz., that sixty and two thousand years are all the same, for I should imagine that some slight chemical change was always going on in a seed. Is this not so? The discussions have stirred me up to send my very small case of the charlock; but as it required some space to give all details, perhaps Lindley will not insert; and if he does, you, you worse than an unbelieving dog, will not, I know, believe. The reason I do not care to try Mr. Bentham's plan is that I think it would be very troublesome, and it would not, if I did not find seed, convince me myself that none were in the earth, for I have found in my salting experiments that the earth clings to the seeds, and the seeds are very difficult to find. Whether washing would do I know not; a gold-washer would succeed, I daresay.

LETTER 580. TO W.J. HOOKER.

Testimonial from Charles Darwin, Esq., M.A., F.R.S. and G.S., late Naturalist to Captain Fitz-Roy's Voyage.

Down House, Farnborough, August 25th, 1845.

I have heard with much interest that your son, Dr. Hooker, is a candidate for the Botanical Chair at Edinburgh. From my former attendance at that University, I am aware how important a post it is for the advancement of science, and I am therefore the more anxious for your son's success, from my firm belief that no one will fulfil its duties with greater zeal or ability. Since his return from the famous Antarctic expedition, I have had, as you are aware, much communication with him, with respect to the collections brought home by myself, and on other scientific subjects; and I cannot express too strongly my admiration at the accuracy of his varied knowledge, and at his powers of generalisation. From Dr. Hooker's disposition, no one, in my opinion, is more fitted to communicate to beginners a strong taste for those pursuits to which he is himself so ardently devoted. For the sake of the advancement of Botany in all its branches, your son has my warmest wishes for his success.

LETTER 581. TO J.D. HOOKER. Down, Thursday [June 11th, 1847].

Many thanks for your kindness about the lodgings—it will be of great use to me. (581/1. The British Association met at Oxford in 1847.) Please let me know the address if Mr. Jacobson succeeds, for I think I shall go on the 22nd and write previously to my lodgings. I have since had a tempting invitation from Daubeny to meet Henslow, etc., but upon the whole, I believe, lodgings will answer best, for then I shall have a secure solitary retreat to rest in.

I am extremely glad I sent the Laburnum (581/2. This refers to the celebrated form known as Cytisus Adami, of which a full account is given in "Variation of Animals and Plants," Volume I., Edition II., page 413. It has been supposed to be a seminal hybrid or graft-hybrid between C. laburnum and C. purpureus. It is remarkable for bearing "on the same tree tufts of dingy red, bright yellow, and purple flowers, borne on branches having widely different leaves and manner of growth." In a paper by Camuzet in the "Annales de la Societe d'Horticulture de Paris, XIII., 1833, page 196, the author tries to show that Cytisus Adami is a seminal hybrid between C. alpinus and C. laburnum. Fuchs ("Sitz. k. Akad. Wien," Bd. 107) and Beijerinck ("K. Akad. Amsterdam," 1900) have spoken on Cytisus Adami, but throw no light on the origin of the hybrid. See letters to Jenner Weir in the present volume.): the raceme grew in centre of tree, and had a most minute tuft of leaves, which presented no unusual appearance: there is now on one raceme a terminal bilateral [i.e., half yellow, half purple] flower, and on other raceme a single terminal pure yellow and one adjoining bilateral flower. If you would like them I will send them; otherwise I would keep them to see whether the bilateral flowers will seed, for Herbert (581/3. Dean Herbert.) says the yellow ones will. Herbert is wrong in thinking there are no somewhat analogous facts: I can tell you some, when we meet. I know not whether botanists consider each petal and stamen an individual; if so, there seems to me no especial difficulty in the case, but if a flower-bud is a unit, are not their flowers very strange?

I have seen Dillwyn in the "Gardeners' Chronicle," and was disgusted at it, for I thought my bilateral flowers would have been a novelty for you.

(581/4. In a letter to Hooker, dated June 2nd, 1847, Darwin makes a bold suggestion as to floral symmetry:—)

I send you a tuft of the quasi-hybrid Laburnum, with two kinds of flowers on same stalk, and with what strikes [me] as very curious (though I know it has been observed before), namely, a flower bilaterally different: one other, I observe, has half its calyx purple. Is this not very curious, and opposed to the morphological idea that a flower is a condensed continuous spire of leaves? Does it not look as if flowers were normally bilateral; just in the same way as we now know that the radiating star-fish, etc., are bilateral? The case reminds me of those insects with exactly half having secondary male characters and the other half female.

(581/5. It is interesting to note his change of view in later years. In an undated letter written to Mr. Spencer, probably in 1873, he says: "With respect to asymmetry in the flowers themselves, I remain contented, from all that I have seen, with adaptation to visits of insects. There is, however, another factor which it is likely enough may have come into play—viz., the protection of the anthers and pollen from the injurious effects of rain. I think so because several flowers inhabiting rainy countries, as A. Kerner has lately shown, bend their heads down in rainy weather.")

LETTER 582. TO J.D. HOOKER. June [1855].

(582/1. This is an early example of Darwin's interest in the movements of plants. Sleeping plants, as is well-known, may acquire a rhythmic movement differing from their natural period, but the precise experiment here described has not, as far as known, been carried out. See Pfeffer, "Periodische Bewegungen," 1875, page 32.)

I thank you much for Hedysarum: I do hope it is not very precious, for, as I told you, it is for probably a most foolish purpose. I read somewhere that no plant closes its leaves so promptly in darkness, and I want to cover it up daily for half an hour, and see if I can TEACH IT to close by itself, or more easily than at first in darkness. I am rather puzzled about its transmission, from not knowing how tender it is...

LETTER 583. TO J.D. HOOKER. Down, July 19th, 1856.

I thank you warmly for the very kind manner with which you have taken my request. It will, in truth, be a most important service to me; for it is absolutely necessary that I should discuss single and double creations, as a very crucial point on the general origin of species, and I must confess, with the aid of all sorts of visionary hypotheses, a very hostile one. I am delighted that you will take up possibility of crossing, no botanist has done so, which I have long regretted, and I am glad to see that it was one of A. De Candolle's desiderata. By the way, he is curiously contradictory on subject. I am far from expecting that no cases of apparent impossibility will be found; but certainly I expect that ultimately they will disappear; for instance, Campanulaceae seems a strong case, but now it is pretty clear that they must be liable to crossing. Sweet-peas (583/1. In Lathyrus odoratus the absence of the proper insect has been supposed to prevent crossing. See "Variation under Domestication," Edition II., Volume II., page 68; but the explanation there given for Pisum may probably apply to Lathyrus.), bee-orchis, and perhaps hollyhocks are, at present, my greatest difficulties; and I find I cannot experimentise by castrating sweet-peas, without doing fatal injury. Formerly I felt most interest on this point as one chief means of eliminating varieties; but I feel interest now in other ways. One general fact [that] makes me believe in my doctrine (583/2. The doctrine which has been epitomised as "Nature abhors perpetual self-fertilisation," and is generally known as Knight's Law or the Knight-Darwin Law, is discussed by Francis Darwin in "Nature," 1898. References are there given to the chief passages in the "Origin of Species," etc., bearing on the question. See Letter 19, Volume I.), is that NO terrestrial animal in which semen is liquid is hermaphrodite except with mutual copulation; in terrestrial plants in which the semen is dry there are many hermaphrodites. Indeed, I do wish I lived at Kew, or at least so that I could see you oftener. To return again to subject of crossing: I have been inclined to speculate so far, as to think (my!?) notion (I say MY notion, but I think others have put forward nearly or quite similar ideas) perhaps explains the frequent separation of the sexes in trees, which I think I have heard remarked (and in looking over the mono- and dioecious Linnean classes in Persoon seems true) are very apt to have sexes separated; for [in] a tree having a vast number of flowers on the same individual, or at least the same stock, each flower, if only hermaphrodite on the common plan, would generally get its own pollen or only pollen from another flower on same stock,—whereas if the sexes were separate there would be a better chance of occasional pollen from another distinct stock. I have thought of testing this in your New Zealand Flora, but I have no standard of comparison, and I found myself bothered by bushes. I should propound that some unknown causes had favoured development of trees and bushes in New Zealand, and consequent on this there had been a development of separation of sexes to prevent too much intermarriage. I do not, of course, suppose the prevention of too much intermarriage the only good of separation of sexes. But such wild notions are not worth troubling you with the reading of.

LETTER 584. TO J.D. HOOKER. Moor Park [May 2nd, 1857].

The most striking case, which I have stumbled on, on apparent, but false relation of structure of plants to climate, seems to be Meyer and Doege's remark that there is not one single, even moderately-sized, family at the Cape of Good Hope which has not one or several species with heath-like foliage; and when we consider this together with the number of true heaths, any one would have been justified, had it not been for our own British heaths (584/1. It is well known that plants with xerophytic characteristics are not confined to dry climates; it is only necessary to mention halophytes, alpine plants and certain epiphytes. The heaths of Northern Europe are placed among the xerophytes by Warming ("Lehrbuch der okologischen Pflanzengeographie," page 234, Berlin, 1896).), in saying that heath-like foliage must stand in direct relation to a dry and moderately warm climate. Does this not strike you as a good case of false relation? I am so pleased with this place and the people here, that I am greatly tempted to bring Etty here, for she has not, on the whole, derived any benefit from Hastings. With thanks for your never failing assistance to me...

I remember that you were surprised at number of seeds germinating in pond mud. I tried a fourth pond, and took about as much mud (rather more than in former case) as would fill a very large breakfast cup, and before I had left home 118 plants had come up; how many more will be up on my return I know not. This bears on chance of birds by their muddy feet transporting fresh-water plants.

This would not be a bad dodge for a collector in country when plants were not in seed, to collect and dry mud from ponds.

LETTER 585. TO ASA GRAY. Down [1857].

I am very glad to hear that you think of discussing the relative ranges of the identical and allied U. States and European species, when you have time. Now this leads me to make a very audacious remark in opposition to what I imagine Hooker has been writing (585/1. See Letter 338, Volume I.), and to your own scientific conscience. I presume he has been urging you to finish your great "Flora" before you do anything else. Now I would say it is your duty to generalise as far as you safely can from your as yet completed work. Undoubtedly careful discrimination of species is the foundation of all good work; but I must look at such papers as yours in Silliman as the fruit. As careful observation is far harder work than generalisation, and still harder than speculation, do you not think it very possible that it may be overvalued? It ought never to be forgotten that the observer can generalise his own observations incomparably better than any one else. How many astronomers have laboured their whole lives on observations, and have not drawn a single conclusion; I think it is Herschel who has remarked how much better it would be if they had paused in their devoted work and seen what they could have deduced from their work. So do pray look at this side of the question, and let us have another paper or two like the last admirable ones. There, am I not an audacious dog!

You ask about my doctrine which led me to expect that trees would tend to have separate sexes. I am inclined to believe that no organic being exists which perpetually self-fertilises itself. This will appear very wild, but I can venture to say that if you were to read my observations on this subject you would agree it is not so wild as it will at first appear to you, from flowers said to be always fertilised in bud, etc. It is a long subject, which I have attended to for eighteen years. Now, it occurred to me that in a large tree with hermaphrodite flowers, we will say it would be ten to one that it would be fertilised by the pollen of its own flower, and a thousand or ten thousand to one that if crossed it would be crossed only with pollen from another flower of same tree, which would be opposed to my doctrine. Therefore, on the great principle of "Nature not lying," I fully expected that trees would be apt to be dioecious or monoecious (which, as pollen has to be carried from flower to flower every time, would favour a cross from another individual of the same species), and so it seems to be in Britain and New Zealand. Nor can the fact be explained by certain families having this structure and chancing to be trees, for the rule seems to hold both in genera and families, as well as in species.

I give you full permission to laugh your fill at this wild speculation; and I do not pretend but what it may be chance which, in this case, has led me apparently right. But I repeat that I feel sure that my doctrine has more probability than at first it appears to have. If you had not asked, I should not have written at such length, though I cannot give any of my reasons.

The Leguminosae are my greatest opposers: yet if I were to trust to observations on insects made during many years, I should fully expect crosses to take place in them; but I cannot find that our garden varieties ever cross each other. I do NOT ask you to take any trouble about it, but if you should by chance come across any intelligent nurseryman, I wish you would enquire whether they take any pains in raising the varieties of papilionaceous plants apart to prevent crossing. (I have seen a statement of naturally formed crossed Phaseoli near N. York.) The worst is that nurserymen are apt to attribute all varieties to crossing.

Finally I incline to believe that every living being requires an occasional cross with a distinct individual; and as trees from the mere multitude of flowers offer an obstacle to this, I suspect this obstacle is counteracted by tendency to have sexes separated. But I have forgotten to say that my maximum difficulty is trees having papilionaceous flowers: some of them, I know, have their keel-petals expanded when ready for fertilisation; but Bentham does not believe that this is general: nevertheless, on principle of nature not lying, I suspect that this will turn out so, or that they are eminently sought by bees dusted with pollen. Again I do NOT ask you to take trouble, but if strolling under your Robinias when in full flower, just look at stamens and pistils whether protruded and whether bees visit them. I must just mention a fact mentioned to me the other day by Sir W. Macarthur, a clever Australian gardener: viz., how odd it was that his Erythrinas in N.S. Wales would not set a seed, without he imitated the movements of the petals which bees cause. Well, as long as you live, you will never, after this fearfully long note, ask me why I believe this or that.

LETTER 586. TO ASA GRAY. June 18th [1857].

It has been extremely kind of you telling me about the trees: now with your facts, and those from Britain, N. Zealand, and Tasmania I shall have fair materials for judging. I am writing this away from home, but I think your fraction of 95/132 is as large as in other cases, and is at least a striking coincidence.

I thank you much for your remarks about my crossing notions, to which, I may add, I was led by exactly the same idea as yours, viz., that crossing must be one means of eliminating variation, and then I wished to make out how far in animals and vegetables this was possible. Papilionaceous flowers are almost dead floorers to me, and I cannot experimentise, as castration alone often produces sterility. I am surprised at what you say about Compositae and Gramineae. From what I have seen of latter they seemed to me (and I have watched wheat, owing to what L. de Longchamps has said on their fertilisation in bud) favourable for crossing; and from Cassini's observations and Kolreuter's on the adhesive pollen, and C.C. Sprengel's, I had concluded that the Compositae were eminently likely (I am aware of the pistil brushing out pollen) to be crossed. (586/1. This is an instance of the curious ignorance of the essential principles of floral mechanism which was to be found even among learned and accomplished botanists such as Gray, before the publication of the "Fertilisation of Orchids." Even in 1863 we find Darwin explaining the meaning of dichogamy in a letter to Gray.) If in some months' time you can find time to tell me whether you have made any observations on the early fertilisation of plants in these two orders, I should be very glad to hear, as it would save me from great blunder. In several published remarks on this subject in various genera it has seemed to me that the early fertilisation has been inferred from the early shedding of the pollen, which I think is clearly a false inference. Another cause, I should think, of the belief of fertilisation in the bud, is the not-rare, abnormal, early maturity of the pistil as described by Gartner. I have hitherto failed in meeting with detailed accounts of regular and normal impregnation in the bud. Podostemon and Subularia under water (and Leguminosae) seem and are strongest cases against me, as far as I as yet know. I am so sorry that you are so overwhelmed with work; it makes your VERY GREAT kindness to me the more striking.

It is really pretty to see how effectual insects are. A short time ago I found a female holly sixty measured yards from any other holly, and I cut off some twigs and took by chance twenty stigmas, cut off their tops, and put them under the microscope: there was pollen on every one, and in profusion on most! weather cloudy and stormy and unfavourable, wind in wrong direction to have brought any.

LETTER 587. TO J.D. HOOKER. Down, January 12th [1858].

I want to ask a question which will take you only few words to answer. It bears on my former belief (and Asa Gray strongly expressed opinion) that Papilionaceous flowers were fatal to my notion of there being no eternal hermaphrodites. First let me say how evidence goes. You will remember my facts going to show that kidney-beans require visits of bees to be fertilised. This has been positively stated to be the case with Lathyrus grandiflorus, and has been very partially verified by me. Sir W. Macarthur tells me that Erythrina will hardly seed in Australia without the petals are moved as if by bee. I have just met the statement that, with common bean, when the humble-bees bite holes at the base of the flower, and therefore cease visiting the mouth of the corolla, "hardly a bean will set." But now comes a much more curious statement, that [in] 1842-43, "since bees were established at Wellington (New Zealand), clover seeds all over the settlement, WHICH IT DID NOT BEFORE." (587/1. See Letter 362, Volume I.) The writer evidently has no idea what the connection can be. Now I cannot help at once connecting this statement (and all the foregoing statements in some degree support each other, as all have been advanced without any sort of theory) with the remarkable absence of Papilionaceous plants in N. Zealand. I see in your list Clianthus, Carmichaelia (four species), a new genus, a shrub, and Edwardsia (is latter Papilionaceous?). Now what I want to know is whether any of these have flowers as small as clover; for if they have large flowers they may be visited by humble-bees, which I think I remember do exist in New Zealand; and which humble-bees would not visit the smaller clover. Even the very minute little yellow clover in England has every flower visited and revisited by hive-bees, as I know by experience. Would it not be a curious case of correlation if it could be shown to be probable that herbaceous and small Leguminosae do not exist because when [their] seeds [are] washed ashore (!!!) no small bees exist there. Though this latter fact must be ascertained. I may not prove anything, but does it not seem odd that so many quite independent facts, or rather statements, should point all in one direction, viz., that bees are necessary to the fertilisation of Papilionaceous flowers?

LETTER 588. TO JOHN LUBBOCK (Lord Avebury). Sunday [1859].

Do you remember calling my attention to certain flowers in the truss of Pelargoniums not being true, or not having the dark shade on the two upper petals? I believe it was Lady Lubbock's observation. I find, as I expected, it is always the central or sub-central flower; but what is far more curious, the nectary, which is blended with the peduncle of the flowers, gradually lessens and quite disappears (588/1. This fact is mentioned in Maxwell Masters' "Vegetable Teratology" (Ray Society's Publications), 1869, page 221.), as the dark shade on the two upper petals disappears. Compare the stalk in the two enclosed parcels, in each of which there is a perfect flower.

Now, if your gardener will not be outrageous, do look over your geraniums and send me a few trusses, if you can find any, having the flowers without the marks, sending me some perfect flowers on same truss. The case seems to me rather a pretty one of correlation of growth; for the calyx also becomes slightly modified in the flowers without marks.

LETTER 589. TO MAXWELL MASTERS. Down, April 7th [1860].

I hope that you will excuse the liberty which I take in writing to you and begging a favour. I have been very much interested by the abstract (too brief) of your lecture at the Royal Institution. Many of the facts alluded to are full of interest for me. But on one point I should be infinitely obliged if you could procure me any information: namely, with respect to sweet-peas. I am a great believer in the natural crossing of individuals of the same species. But I have been assured by Mr. Cattell (589/1. The nurseryman he generally dealt with.), of Westerham, that the several varieties of sweet-pea can be raised close together for a number of years without intercrossing. But on the other hand he stated that they go over the beds, and pull up any false plant, which they very naturally attribute to wrong seeds getting mixed in the lot. After many failures, I succeeded in artificially crossing two varieties, and the offspring out of the same pod, instead of being intermediate, was very nearly like the two pure parents; yet in one, there was a trace of the cross, and these crossed peas in the next generation showed still more plainly their mongrel origin. Now, what I want to know is, whether there is much variation in sweet-peas which might be owing to natural crosses. What I should expect would be that they would keep true for many years, but that occasionally, perhaps at long intervals, there would be a considerable amount of crossing of the varieties grown close together. Can you give, or obtain from your father, any information on this head, and allow me to quote your authority? It would really be a very great favour and kindness.