Maruta Cotula, fide Engelmann, is a scattered and rather scarce plant in Germany. Here, from Boston to St. Louis, it covers the roadsides, and is one of our most social plants. But this plant is doubtless a native of a hotter country than North Germany.

St. John's-wort (Hypericum perforatum) is an intrusive weed in all hilly pastures, etc., and may fairly be called a social plant. In Germany it is not so found, fide Engelmann.

Verbascum Thapsus is diffused over all the country, is vastly more common here than in Germany, fide Engelmann.

I suppose Erodium cicutarium was brought to America with cattle from Spain: it seems to be widely spread over South America out of the Tropics. In Atlantic U.S. it is very scarce and local. But it fills California and the interior of Oregon quite back to the west slope of the Rocky Mountains. Fremont mentions it as the first spring food for his cattle when he reached the western side of the Rocky Mountains. And hardly anybody will believe me when I declare it an introduced plant. I daresay it is equally abundant in Spain. I doubt if it is more so.

Engelmann and I have been noting the species truly indigenous here which, becoming ruderal or campestral, are increasing in the number of individuals instead of diminishing as the country becomes more settled and forests removed. The list of our wild plants which have become true weeds is larger than I had supposed, and these have probably all of them increased their geographical range—at least, have multiplied in numbers in the Northern States since settlements.

Some time ago I sent a copy of the first part of my little essay on the statistics (330/1. "Statistics of the Flora of the Northern U.S." ("Silliman's Journal," XXII. and XXIII.)) of our Northern States plants to Trubner & Co., 12, Paternoster Row, to be thence posted to you. It may have been delayed or failed, so I post another from here.

This is only a beginning. Range of species in latitude must next be tabulated—disjoined species catalogued (i.e. those occurring in remote and entirely separated areas—e.g. Phryma, Monotropa uniflora, etc.)—then some of the curious questions you have suggested—the degree of consanguinity between the related species of our country and other countries, and the comparative range of species in large and small genera, etc., etc. Now, is it worth while to go on at this length of detail? There is no knowing how much space it may cover. Yet, after all, facts in all their fullness is what is wanted, and those not gathered to support (or even to test) any foregone conclusions. It will be prosy, but it may be useful.

Then I have no time properly to revise MSS. and correct oversights. To my vexation, in my short list of our alpine species I have left out, in some unaccountable manner, two of the most characteristic—viz., Cassiope hypnoides and Loiseleuria procumbens. Please add them on page 28.

There is much to be said about our introduced plants. But now, and for some time to come, I must be thinking of quite different matters. I mean to continue this essay in the January number—for which my MSS. must be ready about the 1st of November.

I have not yet attempted to count them up; but of course I am prepared to believe that fully three-fourths of our species common to Europe will [be] found to range northward to the Arctic regions. I merely meant that I had in mind a number that do not; I think the number will not be very small; and I thought you were under the impression that very few absolutely did not so extend northwards. The most striking case I know is that of Convallaria majalis, in the mountains [of] Virginia and North Carolina, and not northward. I believe I mentioned this to you before.

LETTER 331. TO ASA GRAY. Down, October 12th [1856].

I received yesterday your most kind letter of the 23rd and your "Statistics," and two days previously another copy. I thank you cordially for them. Botanists write, of course, for botanists; but, as far as the opinion of an "outsider" goes, I think your paper admirable. I have read carefully a good many papers and works on geographical distribution, and I know of only one essay (viz. Hooker's "New Zealand") that makes any approach to the clearness with which your paper makes a non-botanist appreciate the character of the flora of a country. It is wonderfully condensed (what labour it must have required!). You ask whether such details are worth giving: in my opinion, there is literally not one word too much.

I thank you sincerely for the information about "social" and "varying plants," and likewise for giving me some idea about the proportion (i.e. 1/4th) of European plants which you think do not range to the extreme North. This proportion is very much greater than I had anticipated, from what I picked up in conversation, etc.

To return to your "Statistics." I daresay you will give how many genera (and orders) your 260 introduced plants belong to. I see they include 113 genera non-indigenous. As you have probably a list of the introduced plants, would it be asking too great a favour to send me, per Hooker or otherwise, just the total number of genera and orders to which the introduced plants belong. I am much interested in this, and have found De Candolle's remarks on this subject very instructive.

Nothing has surprised me more than the greater generic and specific affinity with East Asia than with West America. Can you tell me (and I will promise to inflict no other question) whether climate explains this greater affinity? or is it one of the many utterly inexplicable problems in botanical geography? Is East Asia nearly as well known as West America? so that does the state of knowledge allow a pretty fair comparison? I presume it would be impossible, but I think it would make in one point your tables of generic ranges more clear (admirably clear as they seem to me) if you could show, even roughly, what proportion of the genera in common to Europe (i.e. nearly half) are very general or mundane rangers. As your results now stand, at the first glance the affinity seems so very strong to Europe, owing, as I presume, to nearly half of the genera including very many genera common to the world or large portions of it. Europe is thus unfairly exalted. Is this not so? If we had the number of genera strictly, or nearly strictly European, one could compare better with Asia and Southern America, etc. But I dare say this is a Utopian wish, owing to difficulty of saying what genera to call mundane; nor have I my ideas at all clear on the subject, and I have expressed them even less clearly than I have them.

I am so very glad that you intend to work out the north range of the 321 European species; for it seems to me the by far most important element in their distribution.

And I am equally glad that you intend to work out range of species in regard to size of genera—i.e. number of species in genus. I have been attempting to do this in a very few cases, but it is folly for any one but a botanist to attempt it. I must think that De Candolle has fallen into error in attempting to do this for orders instead of for genera—for reasons with which I will not trouble you.

LETTER 332. TO J.D. HOOKER.

(332/1. The "verdict" referred to in the following letter was Sir J.D. Hooker's opinion on Darwin's MS. on geographical distribution. The first paragraph has been already published in "Life and Letters," II., page 86.)

Down, November 4th [1856].

I thank you more cordially than you will think probable for your note. Your verdict has been a great relief. On my honour I had no idea whether or not you would say it was (and I knew you would say it very kindly) so bad, that you would have begged me to have burnt the whole. To my own mind my MS. relieved me of some few difficulties, and the difficulties seemed to me pretty fairly stated; but I had become so bewildered with conflicting facts—evidence, reasoning and opinions—that I felt to myself that I had lost all judgment. Your general verdict is incomparably more favourable than I had anticipated.

Very many thanks for your invitation. I had made up my mind, on my poor wife's account, not to come up to next Phil. Club; but I am so much tempted by your invitation, and my poor dear wife is so good-natured about it, that I think I shall not resist—i.e., if she does not get worse. I would come to dinner at about same time as before, if that would suit you, and I do not hear to the contrary; and would go away by the early train—i.e., about 9 o'clock. I find my present work tries me a good deal, and sets my heart palpitating, so I must be careful. But I should so much like to see Henslow, and likewise meet Lindley if the fates will permit. You will see whether there will be time for any criticism in detail on my MS. before dinner: not that I am in the least hurry, for it will be months before I come again to Geographical Distribution; only I am afraid of your forgetting any remarks.

I do not know whether my very trifling observations on means of distribution are worth your reading, but it amuses me to tell them.

The seeds which the eagle had in [its] stomach for eighteen hours looked so fresh that I would have bet five to one that they would all have grown; but some kinds were ALL killed, and two oats, one canary-seed, one clover, and one beet alone came up! Now I should have not cared swearing that the beet would not have been killed, and I should have fully expected that the clover would have been. These seeds, however, were kept for three days in moist pellets, damp with gastric juice, after being ejected, which would have helped to have injured them.

Lately I have been looking, during a few walks, at excrement of small birds. I have found six kinds of seeds, which is more than I expected. Lastly, I have had a partridge with twenty-two grains of dry earth on one foot, and to my surprise a pebble as big as a tare seed; and I now understand how this is possible, for the bird scratches itself, [and the] little plumous feathers make a sort of very tenacious plaister. Think of the millions of migratory quails (332/2. See "Origin," Edition I., page 363, where the millions of migrating quails occur again.), and it would be strange if some plants have not been transported across good arms of the sea.

Talking of this, I have just read your curious Raoul Island paper. (332/3. "Linn. Soc. Journal." I., 1857.) This looks more like a case of continuous land, or perhaps of several intervening, now lost, islands than any (according to my heterodox notions) I have yet seen. The concordance of the vegetation seems so complete with New Zealand, and with that land alone.

I have read Salter's paper and can hardly stomach it. I wonder whether the lighters were ever used to carry grain and hay to ships. (332/4. Salter, "Linn. Soc. Journal," I., 1857, page 140, "On the Vitality of Seeds after prolonged Immersion in the Sea." It appears that in 1843 the mud was scraped from the bottom of the channels in Poole Harbour, and carried to shore in barges. On this mud a vegetation differing from that of the surrounding shore sprang up.)

Adios, my dear Hooker. I thank you most honestly for your assistance—assistance, by the way, now spread over some dozen years.

P.S.—Wednesday. I see from my wife's expression that she does not really much like my going, and therefore I must give up, of course, this pleasure.

If you should have anything to discuss about my MS., I see that I could get to you by about 12, and then could return by the 2.19 o'clock train, and be home by 5.30 o'clock, and thus I should get two hours' talk. But it would be a considerable exertion for me, and I would not undertake it for mere pleasure's sake, but would very gladly for my book's sake.

LETTER 333. J.D. HOOKER TO CHARLES DARWIN. November 9th, 1856.

I have finished the reading of your MS., and have been very much delighted and instructed. Your case is a most strong one, and gives me a much higher idea of change than I had previously entertained; and though, as you know, never very stubborn about unalterability of specific type, I never felt so shaky about species before.

The first half you will be able to put more clearly when you polish up. I have in several cases made pencil alterations in details as to words, etc., to enable myself to follow better,—some of it is rather stiff reading. I have a page or two of notes for discussion, many of which were answered, as I got further on with the MS., more or less fully. Your doctrine of the cooling of the Tropics is a startling one, when carried to the length of supporting plants of cold temperate regions; and I must confess that, much as I should like it, I can hardly stomach keeping the tropical genera alive in so very cool a greenhouse [pencil note by C.D., "Not so very cool, but northern ones could range further south if not opposed"]. Still I must confess that all your arguments pro may be much stronger put than you have. I am more reconciled to iceberg transport than I was, the more especially as I will give you any length of time to keep vitality in ice, and more than that, will let you transport roots that way also.

(333/1. The above letter was pinned to the following note by Mr. Darwin.)

In answer to this show from similarity of American, and European and Alpine-Arctic plants, that they have travelled enormously without any change.

As sub-arctic, temperate and tropical are all slowly marching toward the equator, the tropical will be first checked and distressed, similarly (333/2. Almost illegible.) the temperate will invade...; after the temperate can [not] advance or do not wish to advance further the arctics will be checked and will invade. The temperates will have been far longer in Tropics than sub-arctics. The sub-arctics will first have to cross temperate [zone] and then Tropics. They would penetrate among strangers, just like the many naturalised plants brought by man, from some unknown advantage. But more, for nearly all have chance of doing so.

(333/3. The point of view is more clearly given in the following letters.)

LETTER 334. TO J.D. HOOKER. Down, November 15th [1856].

I shall not consider all your notes on my MS. for some weeks, till I have done with crossing; but I have not been able to stop myself meditating on your powerful objection to the mundane cold period (334/1. See Letter 49.), viz. that MANY-fold more of the warm-temperate species ought to have crossed the Tropics than of the sub-arctic forms. I really think that to those who deny the modification of species this would absolutely disprove my theory. But according to the notions which I am testing—viz. that species do become changed, and that time is a most important element (which I think I shall be able to show very clearly in this case)—in such change, I think, the result would be as follows. Some of the warm-temperate forms would penetrate the Tropics long before the sub-arctic, and some might get across the equator long before the sub-arctic forms could do so (i.e. always supposing that the cold came on slowly), and therefore these must have been exposed to new associates and new conditions much longer than the sub-arctic. Hence I should infer that we ought to have in the warm-temperate S. hemisphere more representative or modified forms, and fewer identical species than in comparing the colder regions of the N. and S. I have expressed this very obscurely, but you will understand, I think, what I mean. It is a parallel case (but with a greater difference) to the species of the mountains of S. Europe compared with the arctic plants, the S. European alpine species having been isolated for a longer period than on the arctic islands. Whether there are many tolerably close species in the warm-temperate lands of the S. and N. I know not; as in La Plata, Cape of Good Hope, and S. Australia compared to the North, I know not. I presume it would be very difficult to test this, but perhaps you will keep it a little before your mind, for your argument strikes me as by far the most serious difficulty which has occurred to me. All your criticisms and approvals are in simple truth invaluable to me. I fancy I am right in speaking in this note of the species in common to N. and S. as being rather sub-arctic than arctic.

This letter does not require any answer. I have written it to ease myself, and to get you just to bear your argument, under the modification point of view, in mind. I have had this morning a most cruel stab in the side on my notion of the distribution of mammals in relation to soundings.

LETTER 335. J.D. HOOKER TO CHARLES DARWIN. Kew, Sunday [November 1856].

I write only to say that I entirely appreciate your answer to my objection on the score of the comparative rareness of Northern warm-temperate forms in the Southern hemisphere. You certainly have wriggled out of it by getting them more time to change, but as you must admit that the distance traversed is not so great as the arctics have to travel, and the extremes of modifying cause not so great as the arctics undergo, the result should be considerably modified thereby. Thus: the sub-arctics have (1) to travel twice as far, (2) taking twice the time, (3) undergoing many more disturbing influences.

All this you have to meet by giving the North temperate forms simply more time. I think this will hardly hold water.

LETTER 336. TO J.D. HOOKER. Down, November 18th [1856].

Many thanks for your note received this morning; and now for another "wriggle." According to my notions, the sub-arctic species would advance in a body, advancing so as to keep climate nearly the same; and as long as they did this I do not believe there would be any tendency to change, but only when the few got amongst foreign associates. When the tropical species retreated as far as they could to the equator they would halt, and then the confusion would spread back in the line of march from the far north, and the strongest would struggle forward, etc., etc. (But I am getting quite poetical in my wriggles). In short, I THINK the warm-temperates would be exposed very much longer to those causes which I believe are alone efficient in producing change than the sub-arctic; but I must think more over this, and have a good wriggle. I cannot quite agree with your proposition that because the sub-arctic have to travel twice as far they would be more liable to change. Look at the two journeys which the arctics have had from N. to S. and S. to N., with no change, as may be inferred, if my doctrine is correct, from similarity of arctic species in America and Europe and in the Alps. But I will not weary you; but I really and truly think your last objection is not so strong as it looks at first. You never make an objection without doing me much good. Hurrah! a seed has just germinated after 21 1/2 hours in owl's stomach. This, according to ornithologists' calculation, would carry it God knows how many miles; but I think an owl really might go in storm in this time 400 or 500 miles. Adios.

Owls and hawks have often been seen in mid-Atlantic.

(336/1. An interesting letter, dated November 23rd, 1856, occurs in the "Life and Letters," II., page 86, which forms part of this discussion. On page 87 the following passage occurs: "I shall have to discuss and think more about your difficulty of the temperate and sub-arctic forms in the S. hemisphere than I have yet done. But I am inclined to think that I am right (if my general principles are right), that there would be little tendency to the formation of a new species during the period of migration, whether shorter or longer, though considerable variability may have supervened.)

LETTER 337. TO J.D. HOOKER. Down, December 10th [1856].

It is a most tiresome drawback to my satisfaction in writing that, though I leave out a good deal and try to condense, every chapter runs to such an inordinate length. My present chapter on the causes of fertility and sterility and on natural crossing has actually run out to 100 pages MS., and yet I do not think I have put in anything superfluous...

I have for the last fifteen months been tormented and haunted by land-mollusca, which occur on every oceanic island; and I thought that the double creationists or continental extensionists had here a complete victory. The few eggs which I have tried both sink and are killed. No one doubts that salt water would be eminently destructive to them; and I was really in despair, when I thought I would try them when torpid; and this day I have taken a lot out of the sea-water, after exactly seven days' immersion. (337/1. This method of dispersal is not given in the "Origin"; it seems, therefore, probable that further experiments upset the conclusion drawn in 1856. This would account for the satisfaction expressed in the following year at the discovery of another method, on which Darwin wrote to Sir J.D. Hooker: "The distribution of fresh-water molluscs has been a horrid incubus to me, but I think I know my way now. When first hatched they are very active, and I have had thirty or forty crawl on a dead duck's foot; and they cannot be jerked off, and will live fifteen or even twenty-four hours out of water" ("Life and Letters," II., page 93). The published account of these experiments is in the "Origin," Edition I., page 385.) Some sink and some swim; and in both cases I have had (as yet) one come to life again, which has quite astonished and delighted me. I feel as if a thousand-pound weight was taken off my back. Adios, my dear, kind friend.

I must tell you another of my profound experiments! [Frank] said to me: "Why should not a bird be killed (by hawk, lightning, apoplexy, hail, etc.) with seed in its crop, and it would swim?" No sooner said than done: a pigeon has floated for thirty days in salt water with seeds in its crop, and they have grown splendidly; and to my great surprise even tares (Leguminosae, so generally killed by sea-water), which the bird had naturally eaten, have grown well. You will say gulls and dog-fish, etc., would eat up the carcase, and so they would 999 times out of a thousand, but one might escape: I have seen dead land-birds in sea-drift.

LETTER 338. ASA GRAY TO CHARLES DARWIN.

(338/1. In reply to Darwin's letter given in "Life and Letters," II., page 88.)

Cambridge, Mass., February 16th, 1857.

I meant to have replied to your interesting letter of January 1st long before this time, and also that of November 24th, which I doubt if I have ever acknowledged. But after getting my school-book, Lessons in Botany, off my hands—it taking up time far beyond what its size would seem to warrant—I had to fall hard at work upon a collection of small size from Japan—mostly N. Japan, which I am only just done with. As I expected, the number of species common to N. America is considerably increased in this collection, as also the number of closely representative species in the two, and a pretty considerable number of European species too. I have packed off my MSS. (though I hardly know what will become of it), or I would refer you to some illustrations. The greater part of the identical species (of Japan and N. America) are of those extending to or belonging to N.W. coast of America, but there are several peculiar to Japan and E. U. States: e.g. our Viburnum lantanoides is one of Thunberg's species. De Candolle's remarkable case of Phryma, which he so dwells upon, turns out, as Dr. Hooker said it would, to be only one out of a great many cases of the same sort. (Hooker brought Monotropa uniflora, you know, from the Himalayas; and now, by the way, I have it from almost as far south, i.e., from St. Fee, New Granada)...

Well, I never meant to draw any conclusions at all, and am very sorry that the only one I was beguiled into should "rile" (338/2. "One of your conclusions makes me groan, viz., that the line of connection of the strictly alpine plants is through Greenland. I should extremely like to see your reasons published in detail, for it 'riles' me (this is a proper expression, is it not?) dreadfully" (Darwin to Gray, January 1st, 1857, "Life and Letters," II., page 89).) you, as you say it does,—that on page 73 of my second article: for if it troubles you it is not likely to be sound. Of course I had no idea of laying any great stress upon the fact (at first view so unexpected to me) that one-third of our alpine species common to Europe do not reach the Arctic circle; but the remark which I put down was an off-hand inference from what you geologists seem to have settled—viz., that the northern regions must have been a deal cooler than they are now—the northern limit of vegetation therefore much lower than now—about the epoch when it would seem probable that the existing species of our plants were created. At any rate, during the Glacial period there could have been no phaenogamous plants on our continent anywhere near the polar regions; and it seems a good rule to look in the first place for the cause or reason of what now is, in that which immediately preceded. I don't see that Greenland could help us much, but if there was any interchange of species between N. America and N. Europe in those times, was not the communication more likely to be in lower latitudes than over the pole?

If, however, you say—as you may have very good reasons for saying—that the existing species got their present diffusion before the Glacial epoch, I should have no answer. I suppose you must needs assume very great antiquity for species of plants in order to account for their present dispersion, so long as we cling—as one cannot but do—to the idea of the single birthplace of species.

I am curious to see whether, as you suggest, there would be found a harmony or close similarity between the geographical range in this country of the species common to Europe and those strictly representative or strictly congeneric with European species. If I get a little time I will look up the facts: though, as Dr. Hooker rightly tells me, I have no business to be running after side game of any sort, while there is so much I have to do—much more than I shall ever do probably—to finish undertakings I have long ago begun.

...As to your P.S. If you have time to send me a longer list of your protean genera, I will say if they seem to be protean here. Of those you mention:—

Salix, I really know nothing about.

Rubus, the N. American species, with one exception, are very clearly marked indeed.

Mentha, we have only one wild species; that has two pretty well-marked forms, which have been taken for species; one smooth, the other hairy.

Saxifraga, gives no trouble here.

Myosotis, only one or two species here, and those very well marked.

Hieracium, few species, but pretty well marked.

Rosa, putting down a set of nominal species, leaves us four; two of them polymorphous, but easy to distinguish...

LETTER 339. TO J.D. HOOKER. Down, [1857?]

One must judge by one's own light, however imperfect, and as I have found no other book (339/1. A. De Candolle's "Geographie Botanique," 1855.) so useful to me, I am bound to feel grateful: no doubt it is in main part owing to the concentrated light of the noble art of compilation. (339/2. See Letter 49.) I was aware that he was not the first who had insisted on range of Monocots. (Was not R. Brown [with] Flinders?) (339/3. M. Flinders' "Voyage to Terra Australis in 1801-3, in H.M.S. 'Investigator'"; with "Botanical Appendix," by Robert Brown, London, 1814.), and I fancy I only used expression "strongly insisted on,"—but it is quite unimportant.

If you and I had time to waste, I should like to go over his [De Candolle's] book and point out the several subjects in which I fancy he is original. His remarks on the relations of naturalised plants will be very useful to me; on the ranges of large families seemed to me good, though I believe he has made a great blunder in taking families instead of smaller groups, as I have been delighted to find in A. Gray's last paper. But it is no use going on.

I do so wish I could understand clearly why you do not at all believe in accidental means of dispersion of plants. The strongest argument which I can remember at this instant is A. de C., that very widely ranging plants are found as commonly on islands as over continents. It is really provoking to me that the immense contrast in proportion of plants in New Zealand and Australia seems to me a strong argument for non-continuous land; and this does not seem to weigh in the least with you. I wish I could put myself in your frame of mind. In Madeira I find in Wollaston's books a parallel case with your New Zealand case—viz., the striking absence of whole genera and orders now common in Europe, and (as I have just been hunting out) common in Europe in Miocene periods. Of course I can offer no explanation why this or that group is absent; but if the means of introduction have been accidental, then one might expect odd proportions and absences. When we meet, do try and make me see more clearly than I do, your reasons.

LETTER 340. TO J.D. HOOKER. Down, November 14th [1858].

I am heartily glad to hear that my Lyellian notes have been of the slightest use to you. (340/1. The Copley Medal was given to Sir Charles Lyell in 1858. Mr. Darwin supplied Sir J.D. Hooker, who was on the Council of the Royal Society, with notes for the reasons for the award. See Letter 69.) I do not think the view is exaggerated...

Your letter and lists have MOST DEEPLY interested me. First for less important point, about hermaphrodite trees. (340/2. See "Life and Letters," II., page 89. In the "Origin," Edition I., page 100, the author quotes Dr. Hooker to the effect that "the rule does not hold in Australia," i.e., that trees are not more generally unisexual than other plants. In the 6th edition, page 79, Darwin adds, "but if most of the Australian trees are dichogamous, the same result would follow as if they bore flowers with separated sexes.") It is enough to knock me down, yet I can hardly think that British N. America and New Zealand should all have been theoretically right by chance. Have you at Kew any Eucalyptus or Australian Mimosa which sets its seeds? if so, would it be very troublesome to observe when pollen is mature, and whether pollen-tubes enter stigma readily immediately that pollen is mature or some little time afterwards? though if pollen is not mature for some little time after flower opens, the stigma might be ready first, though according to C.C. Sprengel this is a rarer case. I wrote to Muller for chance of his being able and willing to observe this.

Your fact of greater number of European plants (N.B.—But do you mean greater percentage?) in Australia than in S. America is astounding and very unpleasant to me; for from N.W. America (where nearly the same flora exists as in Canada?) to T. del Fuego, there is far more continuous high land than from Europe to Tasmania. There must have, I should think, existed some curious barrier on American High-Road: dryness of Peru, excessive damp of Panama, or some other confounded cause, which either prevented immigration or has since destroyed them. You say I may ask questions, and so I have on enclosed paper; but it will of course be a very different thing whether you will think them worth labour of answering.

May I keep the lists now returned? otherwise I will have them copied.

You said that you would give me a few cases of Australian forms and identical species going north by Malay Archipelago mountains to Philippines and Japan; but if these are given in your "Introduction" this will suffice for me. (340/3. See Hooker's "Introductory Essay," page l.)

Your lists seem to me wonderfully interesting.

According to my theoretical notions, I am not satisfied with what you say about local plants in S.W. corner of Australia (340/4. Sir Joseph replied in an undated letter: "Thanks for your hint. I shall be very cautious how I mention any connection between the varied flora and poor soil of S.W. Australia...It is not by the way only that the species are so numerous, but that these and the genera are so confoundedly well marked. You have, in short, an incredible number of VERY LOCAL, WELL MARKED genera and species crowded into that corner of Australia." See "Introductory Essay to the Flora of Tasmania," 1859, page li.), and the seeds not readily germinating: do be cautious on this; consider lapse of time. It does not suit my stomach at all. It is like Wollaston's confined land-snails in Porto Santo, and confined to same spots since a Tertiary period, being due to their slow crawling powers; and yet we know that other shell-snails have stocked a whole country within a very few years with the same breeding powers, and same crawling powers, when the conditions have been favourable to the life of the introduced species. Hypothetically I should rather look at the case as owing to—but as my notions are not very simple or clear, and only hypothetical, they are not worth inflicting on you.

I had vowed not to mention my everlasting Abstract (340/5. The "Origin of Species" was abbreviated from the MS. of an unpublished book.) to you again, for I am sure I have bothered you far more than enough about it; but as you allude to its previous publication I may say that I have chapters on Instinct and Hybridism to abstract, which may take a fortnight each; and my materials for Palaeontology, Geographical Distribution and Affinities being less worked up, I daresay each of these will take me three weeks, so that I shall not have done at soonest till April, and then my Abstract will in bulk make a small volume. I never give more than one or two instances, and I pass over briefly all difficulties, and yet I cannot make my Abstract shorter, to be satisfactory, than I am now doing, and yet it will expand to small volume.

LETTER 341. TO J.D. HOOKER. Down [November?] 27th [1858].

What you say about the Cape flora's direct relation to Australia is a great trouble to me. Does not Abyssinia highland, (341/1. In a letter to Darwin, December 21st (?), 1858, Sir J.D. Hooker wrote: "Highlands of Abyssinia will not help you to connect the Cape and Australian temperate floras: they want all the types common to both, and, worse than that, India notably wants them. Proteaceae, Thymeleae, Haemodoraceae, Acacia, Rutaceae, of closely allied genera (and in some cases species), are jammed up in S.W. Australia, and C.B.S. [Cape of Good Hope]: add to this the Epacrideae (which are mere (paragraph symbol) of Ericaceae) and the absence or rarity of Rasaceae, etc., etc., and you have an amount [of] similarity in the floras and dissimilarity to that of Abyssinia and India in the same features that does demand an explanation in any theoretical history of Southern vegetation."), and the mountains on W. coast in some degree connect the extra-tropical floras of Cape and Australia? To my mind the enormous importance of the Glacial period rises daily stronger and stronger. I am very glad to hear about S.E. and S.W. Australia: I suspected after my letter was gone that the case must be as it is. You know of course that nearly the same rule holds with birds and mammals. Several years ago I reviewed in the "Annals of Natural History," (341/2. "Annals and Mag. of Nat. Hist." Volume XIX., 1847, pages 53-56, an unsigned review of "A Natural History of the Mammalia," by G.R. Waterhouse, Volume I. The passage referred to is at page 55: "The fact of South Australia possessing only few peculiar species, it having been apparently colonised from the eastern and western coasts, is very interesting; for we believe that Mr. Robert Brown has shown that nearly the same remark is applicable to the plants; and Mr. Gould finds that most of the birds from these opposite shores, though closely allied, are distinct. Considering these facts, together with the presence in South Australia of upraised modern Tertiary deposits and of extinct volcanoes, it seems probable that the eastern and western shores once formed two islands, separated from each other by a shallow sea, with their inhabitants generically, though not specifically, related, exactly as are those of New Guinea and Northern Australia, and that within a geologically recent period a series of upheavals converted the intermediate sea into those desert plains which are now known to stretch from the southern coast far northward, and which then became colonised from the regions to the east and west." On this point see Hooker's "Introductory Essay to the Flora of Tasmania," page ci, where Jukes' views are discussed. For an interesting account of the bearings of the submergence of parts of Australia, see Thiselton-Dyer, "R. Geogr. Soc. Jour." XXII., No. 6.) Waterhouse's "Mammalia," and speculated that these two corners, now separated by gulf and low land, must have existed as two large islands; but it is odd that productions have not become more mingled; but it accords with, I think, a very general rule in the spreading of organic beings. I agree with what you say about Lyell; he learns more by word of mouth than by reading.

Henslow has just gone, and has left me in a fit of enthusiastic admiration of his character. He is a really noble and good man.

LETTER 342. TO G. BENTHAM. Down, December 1st [1858?].

I thank you for so kindly taking the trouble of writing to me, on naturalised plants. I did not know of, or had forgotten, the clover case. How I wish I knew what plants the clover took the place of; but that would require more accurate knowledge of any one piece of ground than I suppose any one has. In the case of trees being so long-lived, I should think it would be extremely difficult to distinguish between true and new spreading of a species, and a rotation of crop. With respect to your idea of plants travelling west, I was much struck by a remark of yours in the penultimate "Linnean Journal" on the spreading of plants from America near Behring Straits. Do you not consider so many more seeds and plants being taken from Europe to America, than in a reverse direction, would go some way to account for comparative fewness of naturalised American plants here? Though I think one might wildly speculate on European weeds having become well fitted for cultivated land, during thousands of years of culture, whereas cultivated land would be a new home for native American weeds, and they would not consequently be able to beat their European rivals when put in contest with them on cultivated land. Here is a bit of wild theory! (342/1. See Asa Gray, "Scientific Papers," 1889, Volume II., page 235, on "The Pertinacity and Predominance of Weeds," where the view here given is adopted. In a letter to Asa Gray (November 6th, 1862), published in the "Life and Letters," II., page 390, Darwin wrote: "Does it not hurt your Yankee pride that we thrash you so confoundedly? I am sure Mrs. Gray will stick up for your own weeds. Ask her whether they are not more honest downright good sort of weeds.")

But I did not sit down intending to scribble thus; but to beg a favour of you. I gave Hooker a list of species of Silene, on which Gartner has experimentised in crossing: now I want EXTREMELY to be permitted to say that such and such are believed by Mr. Bentham to be true species, and such and such to be only varieties. Unfortunately and stupidly, Gartner does not append author's name to the species.

Thank you heartily for what you say about my book; but you will be greatly disappointed; it will be grievously too hypothetical. It will very likely be of no other service than collocating some facts; though I myself think I see my way approximately on the origin of species. But, alas, how frequent, how almost universal it is in an author to persuade himself of the truth of his own dogmas. My only hope is that I certainly see very many difficulties of gigantic stature.

If you can remember any cases of one introduced species beating out or prevailing over another, I should be most thankful to hear it. I believe the common corn-poppy has been seen indigenous in Sicily. I should like to know whether you suppose that seedlings of this wild plant would stand a contest with our own poppy; I should almost expect that our poppies were in some degree acclimatised and accustomed to our cornfields. If this could be shown to be so in this and other cases, I think we could understand why many not-trained American plants would not succeed in our agrarian habitats.

LETTER 343. TO J.D. HOOKER.

(343/1. Mr. Darwin used the knowledge of the spread of introduced plants in North America and Australia to throw light on the cosmic migration of plants. Sir J.D. Hooker apparently objected that it was not fair to argue from agrarian to other plants; he also took a view differing slightly from that of Darwin as to climatal and other natural conditions favouring introduced plants in Australia.)

Down, January 28th, 1859.

Thanks about glaciers. It is a pleasure and profit to me to write to you, and as in your last you have touched on naturalised plants of Australia, I suppose you would not dislike to hear what I can say in answer. At least I know you would not wish me to defer to your authority, as long as not convinced.

I quite agree to what you say about our agrarian plants being accustomed to cultivated land, and so no fair test. Buckman has, I think, published this notion with respect to North America. With respect to roadside plants, I cannot feel so sure that these ought to be excluded, as animals make roads in many wild countries. (343/2. In the account of naturalised plants in Australia in Sir J.D. Hooker's "Introductory Essay to the Flora of Tasmania," 1859, page cvi, many of the plants are marked "Britain—waste places," "Europe—cornfields," etc. In the same list the species which have also invaded North America—a large number—are given. On the margin of Darwin's copy is scribbled in pencil: "Very good, showing how many of the same species are naturalised in Australia and United States, with very different climates; opposed to your conclusion." Sir Joseph supposed that one chief cause of the intrusion of English plants in Australia, and not vice versa, was the great importation of European seed to Australia and the scanty return of Australian seed.)

I have now looked and found passage in F. Muller's (343/3. Ferdinand Muller.) letter to me, in which he says: "In the WILDERNESSES of Australia some European perennials are "advancing in sure progress," "not to be arrested," etc. He gives as instances (so I suppose there are other cases) eleven species, viz., 3. Rumex, Poterium sanguisorba, Potentilla anserina, Medicago sativa, Taraxacum officinale, Marrubium vulgare, Plantago lanceolata, P. major, Lolium perenne. All these are seeding freely. Now I remember, years and years ago, your discussing with me how curiously easily plants get naturalised on uninhabited islands, if ships even touch there. I remember we discussed packages being opened with old hay or straw, etc. Now think of hides and wool (and wool exported largely over Europe), and plants introduced, and samples of corn; and I must think that if Australia had been the old country, and Europe had been the Botany Bay, very few, very much fewer, Australian plants would have run wild in Europe than have now in Australia.

The case seems to me much stronger between La Plata and Spain.

Nevertheless, I will put in my one sentence on this head, illustrating the greater migration during Glacial period from north to south than reversely, very humbly and cautiously. (343/4. "Origin of Species," Edition I., page 379. Darwin refers to the facts given by Hooker and De Candolle showing a stronger migratory flow from north to south than in the opposite direction. Darwin accounts for this by the northern plants having been long subject to severe competition in their northern homes, and having acquired a greater "dominating power" than the southern forms. "Just in the same manner as we see at the present day that very many European productions cover the ground in La Plata, and in a lesser degree in Australia, and have to a certain extent beaten the natives; whereas extremely few southern forms have become naturalised in any part of Europe, though hides, wool, and other objects likely to carry seeds have been largely imported during the last two or three centuries from La Plata, and during the last thirty or forty years from Australia.')

I am very glad to hear you are making good progress with your Australian Introduction. I am, thank God, more than half through my chapter on geographical distribution, and have done the abstract of the Glacial part...

LETTER 344. TO J.D. HOOKER. Down, March 30th, 1859.

Many thanks for your agreeable note. Please keep the geographical MS. till you hear from me, for I may have to beg you to send it to Murray; as through Lyell's intervention I hope he will publish, but he requires first to see MS. (344/1. "The Origin of Species"; see a letter to Lyell in "Life and Letters," II., page 151.)

I demur to what you say that we change climate of the world to account for "migration of bugs, flies, etc." WE do nothing of the sort; for WE rest on scored rocks, old moraines, arctic shells, and mammifers. I have no theory whatever about cause of cold, no more than I have for cause of elevation and subsidence; and I can see no reason why I should not use cold, or elevation, or subsidence to explain any other phenomena, such as distribution. I think if I had space and time I could make a pretty good case against any great continental changes since the Glacial epoch, and this has mainly led me to give up the Lyellian doctrine as insufficient to explain all mutations of climate.

I was amused at the British Museum evidence. (344/2. This refers to the letter to Murchison (Letter 65), published with the evidence of the 1858 enquiry by the Trustees of the British Museum.) I am made to give my opinion so authoritatively on botanical matters!...

As for our belief in the origin of species making any difference in descriptive work, I am sure it is incorrect, for I did all my barnacle work under this point of view. Only I often groaned that I was not allowed simply to decide whether a difference was sufficient to deserve a name.

I am glad to hear about Huxley—a wonderful man.

LETTER 345. TO J.D. HOOKER. Wells Terrace, Ilkley, Otley, Yorkshire, Thursday [before December 9th, 1859].

I have read your discussion (345/1. See "Introductory Essay," page c. Darwin did not receive this work until December 23rd, so that the reference is to proof-sheets.), as usual, with great interest. The points are awfully intricate, almost at present beyond the confines of knowledge. The view which I should have looked at as perhaps most probable (though it hardly differs from yours) is that the whole world during the Secondary ages was inhabited by marsupials, araucarias (Mem.—Fossil wood so common of this nature in South America (345/2. See Letter 6, Note.)), Banksia, etc.; and that these were supplanted and exterminated in the greater area of the north, but were left alive in the south. Whence these very ancient forms originally proceeded seems a hopeless enquiry.

Your remarks on the passage of the northern forms southward, and of the southern forms of no kinds passing northward, seem to me grand. Admirable, also, are your remarks on the struggle of vegetation: I find that I have rather misunderstood you, for I feared I differed from you, which I see is hardly the case at all. I cannot help suspecting that you put rather too much weight to climate in the case of Australia. La Plata seems to present such analogous facts, though I suppose the naturalisation of European plants has there taken place on a still larger scale than in Australia...

You will get four copies of my book—one for self, and three for the foreign botanists—in about ten days, or sooner; i.e., as soon as the sheets can be bound in cloth. I hope this will not be too late for your parcels.

When you read my volume, use your pencil and score, so that some time I may have a talk with you on any criticisms.

LETTER 346. TO HUGH FALCONER. Down, December 17th, [1859].

Whilst I think of it, let me tell you that years ago I remember seeing in the Museum of the Geological Society a tooth of hippopotamus from Madagascar: this, on geographical and all other grounds, ought to be looked to. Pray make a note of this fact. (346/1. At a meeting of the Geological Society, May 1st, 1833, a letter was read from Mr. Telfair to Sir Alex. Johnstone, accompanying a specimen of recent conglomerate rock, from the island of Madagascar, containing fragments of a tusk, and part of a molar tooth of a hippopotamus ("Proc. Geol. Soc." 1833, page 479). There is a reference to these remains of hippopotamus in a paper by Mr. R.B. Newton in the "Geol. Mag." Volume X., 1893; and in Dr. Forsyth Major's memoir on Megaladapis Madagascariensis ("Phil. Trans. R. Soc." Volume 185, page 30, 1894).

Since this letter was written, several bones belonging to two or possibly three species of hippopotamus have been found in Madagascar. See Forsyth Major, "On the General Results of a Zoological Expedition to Madagascar in 1894-96" ("Proc. Zool. Soc." 1896, page 971.))

We have returned a week ago from Ilkley, and it has done me some decided good. In London I saw Lyell (the poor man who has "rushed into the bosom of two heresies"—by the way, I saw his celts, and how intensely interesting), and he told me that you were very antagonistic to my views on species. I well knew this would be the case. I must freely confess, the difficulties and objections are terrific; but I cannot believe that a false theory would explain, as it seems to me it does explain, so many classes of facts. Do you ever see Wollaston? He and you would agree nicely about my book (346/2. "Origin of Species," 1859.)—ill luck to both of you. If you have anything at all pleasant for me to hear, do write; and if all that you can say is very unpleasant, it will do you good to expectorate. And it is well known that you are very fond of writing letters. Farewell, my good old friend and enemy.

Do make a note about the hippopotamus. If you are such a gentleman as to write, pray tell me how Torquay agrees with your health.

(PLATE: DR. ASA GRAY, 1867.)

LETTER 347. TO ASA GRAY. Down, December 24th [1859].

I have been for ten weeks at Water-cure, and on my return a fortnight ago through London I found a copy of your Memoir, and heartily do I thank you for it. (347/1. "Diagnostic Characters of New Species of Phaenogamous Plants collected in Japan by Charles Wright...with Observations upon the Relations of the Japanese Flora to that of North America and of other parts of the Northern Temperate Zone" ("Mem. American Acad. Arts and Sci." Volume VI., page 377, 1857).) I have not read it, and shall not be able very soon, for I am much overworked, and my stomach has got nearly as bad as ever.

With respect to the discussion on climate, I beg you to believe that I never put myself for a moment in competition with Dana; but when one has thought on a subject, one cannot avoid forming some opinion. What I wrote to Hooker I forget, after reading only a few sheets of your Memoir, which I saw would be full of interest to me. Hooker asked me to write to you, but, as I told him, I would not presume to express an opinion to you without careful deliberation. What he wrote I know not: I had previously several years ago seen (by whom I forget) some speculation on warmer period in the U. States subsequent to Glacial period; and I had consulted Lyell, who seemed much to doubt, and Lyell's judgment is really admirably cautious. The arguments advanced in your paper and in your letter seem to me hardly sufficient; not that I should be at all sorry to admit this subsequent and intercalated warmer period—the more changes the merrier, I think. On the other hand, I do not believe that introduction of the Old World forms into New World subsequent to the Glacial period will do for the modified or representative forms in the two Worlds. There has been too much change in comparison with the little change of isolated alpine forms; but you will see this in my book. (347/2. "Origin of Species" (1859), Chapter XI., pages 365 et seq.) I may just make a few remarks why at first sight I do not attach much weight to the argument in your letter about the warmer climate. Firstly, about the level of the land having been lower subsequently to Glacial period, as evidenced by the whole, etc., I doubt whether meteorological knowledge is sufficient for this deduction: turning to the S. hemisphere, it might be argued that a greater extent of water made the temperature lower; and when much of the northern land was lower, it would have been covered by the sea and intermigration between Old and New Worlds would have been checked. Secondly, I doubt whether any inference on nature of climate can be deduced from extinct species of mammals. If the musk-ox and deer of great size of your Barren-Grounds had been known only by fossil bones, who would have ventured to surmise the excessively cold climate they lived under? With respect to food of large animals, if you care about the subject will you turn to my discussion on this subject partly in respect to the Elephas primigenius in my "Journal of Researches" (Murray's Home and Colonial Library), Chapter V., page 85. (347/3. "The firm conviction of the necessity of a vegetation possessing a character of tropical luxuriance to support such large animals, and the impossibility of reconciling this with the proximity of perpetual congelation, was one chief cause of the several theories of sudden revolutions of climate...I am far from supposing that the climate has not changed since the period when these animals lived, which now lie buried in the ice. At present I only wish to show that as far as quantity of food alone is concerned, the ancient rhinoceroses might have roamed over the steppes of Central Siberia even in their present condition, as well as the living rhinoceroses and elephants over the karoos of Southern Africa" ("Journal of Researches," page 89, 1888).) In this country we infer from remains of Elephas primigenius that the climate at the period of its embedment was very severe, as seems countenanced by its woolly covering, by the nature of the deposits with angular fragments, the nature of the co-embedded shells, and co-existence of the musk-ox. I had formerly gathered from Lyell that the relative position of the Megatherium and Mylodon with respect to the Glacial deposits, had not been well made out; but perhaps it has been so recently. Such are my reasons for not as yet admitting the warmer period subsequent to Glacial epoch; but I daresay I may be quite wrong, and shall not be at all sorry to be proved so.

I shall assuredly read your essay with care, for I have seen as yet only a fragment, and very likely some parts, which I could not formerly clearly understand, will be clear enough.

LETTER 348. TO J.D. HOOKER. Down, [December] 26th, [1859].

I have just read with intense interest as far as page xxvi (348/1. For Darwin's impression of the "Introductory Essay to the Tasmanian Flora" as a whole, see "Life and Letters," II., page 257.), i.e. to where you treat of the Australian Flora itself; and the latter part I remember thinking most of in the proof-sheets. Either you have altered a good deal, or I did not see all or was purblind, for I have been much more interested with all the first part than I was before,—not that I did not like it at first. All seems to me very clearly written, and I have been baulked at only one sentence. I think, on the whole, I like the geological, or rather palaeontological, discussion best: it seems to me excellent, and admirably cautious. I agree with all that you say as far as my want of special knowledge allows me to judge.

I have no criticisms of any importance, but I should have liked more facts in one or two places, which I shall not ask about. I rather demur to the fairness of your comparison of rising and sinking areas (348/2. Hooker, op. cit., page xv, paragraph 24. Hooker's view was that sinking islands "contain comparatively fewer species and fewer peculiar generic types than those which are rising." In Darwin's copy of the Essay is written on the margin of page xvi: "I doubt whole case."), as in the Indian Ocean you compare volcanic land with exclusively coral islands, and these latter are very small in area and have very peculiar soil, and during their formation are likely to have been utterly submerged, perhaps many times, and restocked with existing plants. In the Pacific, ignorance of Marianne and Caroline and other chief islands almost prevent comparison (348/3. Gambier Island would be an interesting case. [Note in original.]); and is it right to include American islands like Juan Fernandez and Galapagos? In such lofty and probably ancient islands as Sandwich and Tahiti it cannot make much difference in the flora whether they have sunk or risen a few thousand feet of late ages.

I wish you could work in your notion of certain parts of the Tropics having kept hot, whilst other parts were cooled; I tried this scheme in my mind, and it seemed to fail. On the whole, I like very much all that I have read of your Introduction, and I cannot doubt that it will have great weight in converting other botanists from the doctrine of immutable creation. What a lot of matter there is in one of your pages!

There are many points I wish much to discuss with you.

How I wish you could work out the Pacific floras: I remember ages ago reading some of your MS. In Paris there must be, I should think, materials from French voyages. But of all places in the world I should like to see a good flora of the Sandwich Islands. (348/4. See Hillebrand, "Flora of the Hawaiian Islands," 1888.) I would subscribe 50 pounds to any collector to go there and work at the islands. Would it not pay for a collector to go there, especially if aided by any subscription? It would be a fair occasion to ask for aid from the Government grant of the Royal Society. I think it is the most isolated group in the world, and the islands themselves well isolated from each other.

LETTER 349. TO ASA GRAY. Down, January 7th [1860].

I have just finished your Japan memoir (349/1. "Diagnostic Characters of New Species of Phaenogamous Plants collected in Japan by Charles Wright. With observations upon the Relations of the Japanese Flora to that of North America, etc.: 1857-59."—"Memoirs of Amer. Acad." VI.), and I must thank you for the extreme interest with which I have read it. It seems to me a most curious case of distribution; and how very well you argue, and put the case from analogy on the high probability of single centres of creation. That great man Agassiz, when he comes to reason, seems to me as great in taking a wrong view as he is great in observing and classifying. One of the points which has struck me as most remarkable and inexplicable in your memoir is the number of monotypic (or nearly so) genera amongst the representative forms of Japan and N. America. And how very singular the preponderance of identical and representative species in Eastern, compared with Western, America. I have no good map showing how wide the moderately low country is on the west side of the Rocky Mountains; nor, of course, do I know whether the whole of the low western territory has been botanised; but it has occurred to me, looking at such maps as I have, that the eastern area must be larger than the western, which would account to a certain small extent for preponderance on eastern side of the representative species. Is there any truth in this suspicion? Your memoir sets me marvelling and reflecting. I confess I am not able quite to understand your Geology at pages 447, 448; but you would probably not care to hear my difficulties, and therefore I will not trouble you with them.

I was so grieved to get a letter from Dana at Florence, giving me a very poor (though improved) account of his health.

LETTER 350. TO T.H. HUXLEY. 15, Marine Parade, Eastbourne, November 1st [1860].

Your note has been wonderfully interesting. Your term, "pithecoid man," is a whole paper and theory in itself. How I hope the skull of the new Macrauchenia has come. It is grand. I return Hooker's letter, with very many thanks. The glacial action on Lebanon is particularly interesting, considering its position between Europe and Himalaya. I get more and more convinced that my doctrine of mundane Glacial period is correct (350/1. In the 1st edition of the "Origin," page 373, Darwin argues in favour of a Glacial period practically simultaneous over the globe. In the 5th edition, 1869, page 451, he adopted Mr. Croll's views on the alternation of cold periods in the northern and southern hemispheres. An interesting modification of the mundane Glacial period theory is given in Belt's "The Naturalist in Nicaragua," 1874, page 265. Mr. Belt's views are discussed in Wallace's "Geogr. Distribution," 1876, Volume I., page 151.), and that it is the most important of all late phenomena with respect to distribution of plants and animals. I hope your Review (350/2. The history of the foundation of the "Natural History Review" is given in Huxley's "Life and Letters," Volume I., page 209. See Letter 107.) progresses favourably. I am exhausted and not well, so write briefly; for we have had nine days of as much misery as man can endure. My poor daughter has suffered pitiably, and night and day required three persons to support her. The crisis of extreme danger is over, and she is rallying surprisingly, but the doctors are yet doubtful of ultimate issue. But the suffering was so pitiable I almost got to wish to see her die. She is easy now. When she will be fit to travel home I know not. I most sincerely hope that Mrs. Huxley keeps up pretty well. The work which most men have to do is a blessing to them in such cases as yours. God bless you.

Sir H. Holland came here to see her, and was wonderfully kind.

LETTER 351. TO C. LYELL. Down, November 20th [1860].

I quite agree in admiration of Forbes' Essay (351/1. "Memoir of the Geolog. Survey of the United Kingdom," Volume I., 1846.), yet, on my life, I think it has done, in some respects, as much mischief as good. Those who believe in vast continental extensions will never investigate means of distribution. Good heavens, look at Heer's map of Atlantis! I thought his division and lines of travel of the British plants very wild, and with hardly any foundation. I quite agree with what you say of almost certainty of Glacial epoch having destroyed the Spanish saxifrages, etc., in Ireland. (351/2. See Letter 20.) I remember well discussing this with Hooker; and I suggested that a slightly different or more equable and humid climate might have allowed (with perhaps some extension of land) the plants in question to have grown along the entire western shores between Spain and Ireland, and that subsequently they became extinct, except at the present points under an oceanic climate. The point of Devonshire now has a touch of the same character.

I demur in this particular case to Forbes' transportal by ice. The subject has rather gone out of my mind, and it is not worth looking to my MS. discussion on migration during the Glacial period; but I remember that the distribution of mammalia, and the very regular relation of the Alpine plants to points due north (alluded to in "Origin"), seemed to indicate continuous land at close of Glacial period.

LETTER 352. TO J.D. HOOKER. Down, March 18th [1861].

I have been recalling my thoughts on the question whether the Glacial period affected the whole world contemporaneously, or only one longitudinal belt after another. To my sorrow my old reasons for rejecting the latter alternative seem to me sufficient, and I should very much like to know what you think. Let us suppose that the cold affected the two Americas either before or after the Old World. Let it advance first either from north or south till the Tropics became slightly cooled, and a few temperate forms reached the Silla of Caracas and the mountains of Brazil. You would say, I suppose, that nearly all the tropical productions would be killed; and that subsequently, after the cold had moderated, tropical plants immigrated from the other non-chilled parts of the world. But this is impossible unless you bridge over the tropical parts of the Atlantic—a doctrine which you know I cannot admit, though in some respects wishing I could. Oswald Heer would make nothing of such a bridge. When the Glacial period affected the Old World, would it not be rather rash to suppose that the meridian of India, the Malay Archipelago, and Australia were refrigerated, and Africa not refrigerated? But let us grant that this was so; let us bridge over the Red Sea (though rather opposed to the former almost certain communication between the Red Sea and the Mediterranean); let us grant that Arabia and Persia were damp and fit for the passage of tropical plants: nevertheless, just look at the globe and fancy the cold slowly coming on, and the plants under the tropics travelling towards the equator, and it seems to me highly improbable that they could escape from India to the still hot regions of Africa, for they would have to go westward with a little northing round the northern shores of the Indian Ocean. So if Africa were refrigerated first, there would be considerable difficulty in the tropical productions of Africa escaping into the still hot regions of India. Here again you would have to bridge over the Indian Ocean within so very recent a period, and not in the line of the Laccadive Archipelago. If you suppose the cold to travel from the southern pole northwards, it will not help us, unless we suppose that the countries immediately north of the northern tropic were at the same time warmer, so as to allow free passage from India to Africa, which seems to me too complex and unsupported an hypothesis to admit. Therefore I cannot see that the supposition of different longitudinal belts of the world being cooled at different periods helps us much. The supposition of the whole world being cooled contemporaneously (but perhaps not quite equally, South America being less cooled than the Old World) seems to me the simplest hypothesis, and does not add to the great difficulty of all the tropical productions not having been exterminated. I still think that a few species of each still existing tropical genus must have survived in the hottest or most favourable spots, either dry or damp. The tropical productions, though much distressed by the fall of temperature, would still be under the same conditions of the length of the day, etc., and would be still exposed to nearly the same enemies, as insects and other animals; whereas the invading temperate productions, though finding a favouring temperature, would have some of their conditions of life new, and would be exposed to many new enemies. But I fully admit the difficulty to be very great. I cannot see the full force of your difficulty of no known cause of a mundane change of temperature. We know no cause of continental elevations and depressions, yet we admit them. Can you believe, looking to Europe alone, that the intense cold, which must have prevailed when such gigantic glaciers extended on the plains of N. Italy, was due merely to changed positions of land within so recent a period? I cannot. It would be far too long a story, but it could, I think, be clearly shown that all our continents existed approximately in their present positions long before the Glacial period; which seems opposed to such gigantic geographical changes necessary to cause such a vast fall of temperature. The Glacial period endured in Europe and North America whilst the level of the land oscillated in height fully 3,000 feet, and this does not look as if changed level was the cause of the Glacial period. But I have written an unreasonably long discussion. Do not answer me at length, but send me a few words some time on the subject.

I have had this copied, that it might not bore you too much to read it.

A few words more. When equatorial productions were dreadfully distressed by fall of temperature, and probably by changed humidity, and changed proportional numbers of other plants and enemies (though they might favour some of the species), I must admit that they all would be exterminated if productions exactly fitted, not only for the climate, but for all the conditions of the equatorial regions during the Glacial period existed and could everywhere have immigrated. But the productions of the temperate regions would have probably found, under the equator, in their new homes and soils, considerably different conditions of humidity and periodicity, and they would have encountered a new set of enemies (a most important consideration); for there seems good reason to believe that animals were not able to migrate nearly to the extent to which plants did during the Glacial period. Hence I can persuade myself that the temperate productions would not entirely replace and exterminate the productions of the cooled tropics, but would become partially mingled with them.

I am far from satisfied with what I have scribbled. I conclude that there must have been a mundane Glacial period, and that the difficulties are much the same whether we suppose it contemporaneous over the world, or that longitudinal belts were affected one after the other. For Heaven's sake forgive me!

LETTER 353. TO H.W. BATES. March 26th [1861].

I have been particularly struck by your remarks on the Glacial period. (353/1. In his "Contributions to the Insect Fauna of the Amazon Valley," "Trans. Entom. Soc." Volume V., page 335 (read November 24th, 1860), Mr. Bates discusses the migration of species from the equatorial regions after the Glacial period. He arrives at a result which, he points out, "is highly interesting as bearing upon the question of how far extinction is likely to have occurred in equatorial regions during the time of the Glacial epoch."..."The result is plain, that there has always (at least throughout immense geological epochs) been an equatorial fauna rich in endemic species, and that extinction cannot have prevailed to any extent within a period of time so comparatively modern as the Glacial epoch in geology." This conclusion does not support the view expressed in the "Origin of Species" (Edition I., chapter XI., page 378) that the refrigeration of the earth extended to the equatorial regions. (Bates, loc. cit., pages 352, 353.)) You seem to me to have put the case with admirable clearness and with crushing force. I am quite staggered with the blow, and do not know what to think. Of late several facts have turned up leading me to believe more firmly that the Glacial period did affect the equatorial regions; but I can make no answer to your argument, and am completely in a cleft stick. By an odd chance I have only a few days ago been discussing this subject, in relation to plants, with Dr. Hooker, who believes to a certain extent, but strongly urged the little apparent extinction in the equatorial regions. I stated in a letter some days ago to him that the tropics of S. America seem to have suffered less than the Old World. There are many perplexing points; temperate plants seem to have migrated far more than animals. Possibly species may have been formed more rapidly within tropics than one would have expected. I freely confess that you have confounded me; but I cannot yet give up my belief that the Glacial period did to certain extent affect the tropics.

LETTER 354. TO J.D. HOOKER. Down, February 25th [1862].

I have almost finished your Arctic paper, and I must tell you how I admire it. (354/1. "Outlines of the Distribution of Arctic Plants" [Read June 21st, 1860], "Linn. Soc. Trans." XXIII., 1862, page 251. The author's remarks on Mr. Darwin's theories of Geographical Distribution are given at page 255: they are written in a characteristically generous spirit.) The subject, treated as you have treated it, is really magnificent. Good Heaven, what labour it must have cost you! And what a grand prospect there is for the future. I need not say how much pleased I am at your notice of my work; for you know that I regard your opinion more than that of all others. Such papers are the real engine to compel people to reflect on modification of species; any one with an enquiring mind could hardly fail to wish to consider the whole subject after reading your paper. By Jove! you will be driven, nolens volens, to a cooled globe. Think of your own case of Abyssinia and Fernando Po, and South Africa, and of your Lebanon case (354/2. See "Origin," Edition VI., page 337.); grant that there are highlands to favour migration, but surely the lowlands must have been somewhat cooled. What a splendid new and original evidence and case is that of Greenland: I cannot see how, even by granting bridges of continuous land, one can understand the existing flora. I should think from the state of Scotland and America, and from isothermals, that during the coldest part of Glacial period, Greenland must have been quite depopulated. Like a dog to his vomit, I cannot help going back and leaning to accidental means of transport by ice and currents. How curious also is the case of Iceland. What a splendid paper you have made of the subject. When we meet I must ask you how much you attribute richness of flora of Lapland to mere climate; it seems to me very marvellous that this point should have been a sort of focus of radiation; if, however, it is unnaturally rich, i.e. contains more species than it ought to do for its latitude, in comparison with the other Arctic regions, would it not thus falsely seem a focus of radiation? But I shall hereafter have to go over and over again your paper; at present I am quite muddy on the subject. How very odd, on any view, the relation of Greenland to the mountains of E. N. America; this looks as if there had been wholesale extinction in E. N. America. But I must not run on. By the way, I find Link in 1820 speculated on relation of Alpine and Arctic plants being due to former colder climate, which he attributed to higher mountains cutting off the warm southern winds.

LETTER 355. J.D. HOOKER TO CHARLES DARWIN. Kew, November 2nd, 1862.

Did I tell you how deeply pleased I was with Gray's notice of my Arctic essay? (355/1. "American Journal of Science and Arts," XXXIV., and in Gray's "Scientific Papers," Volume I., page 122.) It was awfully good of him, for I am sure he must have seen several blunders. He tells me that Dr. Dawson (355/2. A letter (No. 144) by Sir J.D. Hooker, dated November 7th, 1862, on this subject occurs in the Evolutionary section.) is down on me, and I have a very nice lecture on Arctic and Alpine plants from Dr. D., with a critique on the Arctic essay—which he did not see till afterwards. He has found some mares' nests in my essay, and one very venial blunder in the tables—he seems to HATE Darwinism—he accuses me of overlooking the geological facts, and dwells much on my overlooking subsidence of temperate America during Glacial period—and my asserting a subsidence of Arctic America, which never entered into my head. I wish, however, if it would not make your head ache too much, you would just look over my first three pages, and tell me if I have outraged any geological fact or made any oversights. I expounded the whole thing twice to Lyell before I printed it, with map and tables, intending to get (and I thought I had) his imprimatur for all I did and said; but when here three nights ago, I found he was as ignorant of my having written an Arctic essay as could be! And so I suppose he either did not take it in, or thought it of little consequence. Hector approved of it in toto. I need hardly say that I set out on biological grounds, and hold myself as independent of theories of subsidence as you do of the opinions of physicists on heat of globe! I have written a long [letter] to Dawson.

By the way, did you see the "Athenaeum" notice of L. Bonaparte's Basque and Finnish language?—is it not possible that the Basques are Finns left behind after the Glacial period, like the Arctic plants? I have often thought this theory would explain the Mexican and Chinese national affinities. I am plodding away at Welwitschia by night and Genera Plantarum by day. We had a very jolly dinner at the Club on Thursday. We are all well.

LETTER 356. TO J.D. HOOKER. Down, November 4th [1862].

I have read the pages (356/1. The paper on Arctic plants in Volume XXIII. of the Linnean Society's "Transactions," 1860-62.) attentively (with even very much more admiration than the first time) and cannot imagine what makes Dr. D. accuse you of asserting a subsidence of Arctic America. (356/2. The late Sir J.W. Dawson wrote a review (signed J.W.D) of Hooker's Arctic paper which appeared in the "Canadian Naturalist," 1862, Volume VII., page 334. The chief part of the article is made up of quotations from Asa Gray's article referred to below. The remainder is a summary of geological arguments against Hooker's views. We do not find the accusation referred to above, which seems to have appeared in a lecture.) No doubt there was a subsidence of N. America during the Glacial period, and over a large part, but to maintain that the subsidence extended over nearly the whole breadth of the continent, or lasted during the whole Glacial period, I do not believe he can support. I suspect much of the evidence of subsidence during the Glacial period there will prove false, as it largely rests on ice-action, which is becoming, as you know, to be viewed as more and more subaerial. If Dawson has published criticisms I should like to see them. I have heard he is rabid against me, and no doubt partly in consequence, against anything you write in my favour (and never was anything published more favourable than the Arctic paper). Lyell had difficulty in preventing Dawson reviewing the "Origin" (356/3. Dawson reviewed the "Origin" in the "Canadian Naturalist," 1860.) on hearsay, without having looked at it. No spirit of fairness can be expected from so biassed a judge.

All I can say is that your few first pages have impressed me far more this reading than the first time. Can the Scandinavian portion of the flora be so potent (356/4. Dr. Hooker wrote: "Regarded as a whole the Arctic flora is decidedly Scandinavian; for Arctic Scandinavia, or Lapland, though a very small tract of land, contains by far the richest Arctic flora, amounting to three-fourths of the whole"; he pointed out "that the Scandinavian flora is present in every latitude of the globe, and is the only one that is so" (quoted by Gray, loc. cit. infra).) from having been preserved in that corner, warmed by the Gulf Stream, and from now alone representing the entire circumpolar flora, during the warmer pre-Glacial period? From the first I have not been able to resist the impression (shared by Asa Gray, whose Review (356/5. Asa Gray's "Scientific Papers," Volume I., page 122.) on you pleased me much) that during the Glacial period there must have been almost entire extinction in Greenland; for depth of sea does not favour former southerly extension of land there. (356/6. In the driving southward of the vegetation by the Glacial epoch the Greenland flora would be "driven into the sea, that is, exterminated." (Hooker quoted by Gray, loc. cit. page 124.) I must suspect that plants have been largely introduced by sea currents, which bring so much wood from N. Europe. But here we shall split as wide as the poles asunder. All the world could not persuade me, if it tried, that yours is not a grand essay. I do not quite understand whether it is this essay that Dawson has been "down on." What a curious notion about Glacial climate, and Basques and Finns! Are the Basques mountaineers—I hope so. I am sorry I have not seen the "Athenaeum," but I now take in the "Parthenon." By the way, I have just read with much interest Max Muller (356/7. Probably his "Lectures on the Science of Language," 1861-64.); the last part, about first origin of language, seems the least satisfactory part.

Pray thank Oliver heartily for his heap of references on poisons. (356/8. Doubtless in connection with Darwin's work on Drosera: he was working at this subject during his stay at Bournemouth in the autumn of 1862.) How the devil does he find them out?

I must not indulge [myself] with Cypripedium. Asa Gray has made out pretty clearly that, at least in some cases, the act of fertilisation is effected by small insects being forced to crawl in and out of the flower in a particular direction; and perhaps I am quite wrong that it is ever effected by the proboscis.

I retract so far that if you have the rare C. hirsutissimum, I should very much like to examine a cut single flower; for I saw one at a flower show, and as far as I could see, it seemed widely different from other forms.

P.S.—Answer this, if by chance you can. I remember distinctly having read in some book of travels, I am nearly sure in Australia, an account of the natives, during famines, trying and cooking in all sorts of ways various vegetable productions, and sometimes being injured by them. Can you remember any such account? I want to find it. I thought it was in Sir G. Grey, but it is not. Could it have been in Eyre's book?

LETTER 357. J.D. HOOKER TO CHARLES DARWIN. [November 1862].

...I have speculated on the probability of there having been a post-Glacial Arctic-Norwego-Greenland in connection, which would account for the strong fact, that temperate Greenland is as Arctic as Arctic Greenland is—a fact, to me, of astounding force. I do confess, that a northern migration would thus fill Greenland as it is filled, in so far as the whole flora (temperate and Arctic) would be Arctic,—but then the same plants should have gone to the other Polar islands, and above all, so many Scandinavian Arctic plants should not be absent in Greenland, still less should whole Natural Orders be absent, and above all the Arctic Leguminosae. It is difficult (as I have told Dawson) to conceive of the force with which arguments drawn from the absence of certain familiar ubiquitous plants strike the botanists. I would not throw over altogether ice-transport and water-transport, but I cannot realise their giving rise to such anomalies, in the distribution, as Greenland presents. So, too, I have always felt the force of your objection, that Greenland should have been depopulated in the Glacial period, but then reflected that vegetation now ascends I forget how high (about 1,000 feet) in Disco, in 70 deg, and that even in a Glacial ocean there may always have been lurking-places for the few hundred plants Greenland now possesses. Supposing Greenland were repeopled from Scandinavia over ocean way, why should Carices be the chief things brought? Why should there have been no Leguminosae brought, no plants but high Arctic?—why no Caltha palustris, which gilds the marshes of Norway and paints the housetops of Iceland? In short, to my eyes, the trans-oceanic migration would no more make such an assemblage than special creations would account for representative species—and no "ingenious wriggling" ever satisfied me that it would. There, then!

I dined with Henry Christy last night, who was just returned from celt hunting with Lartet, amongst the Basques,—they are Pyreneans. Lubbock was there, and told me that my precious speculation was one of Von Baer's, and that the Finns are supposed to have made the Kjokken moddings. I read Max Muller a year ago—and quite agree, first part is excellent; last, on origin of language, fatuous and feeble as a scientific argument.

LETTER 358. TO J.D. HOOKER. Down, November 12th [1862].

I return by this post Dawson's lecture, which seems to me interesting, but with nothing new. I think he must be rather conceited, with his "If Dr. Hooker had known this and that, he would have said so and so." It seems to me absurd in Dawson assuming that North America was under sea during the whole Glacial period. Certainly Greenland is a most curious and difficult problem. But as for the Leguminosae, the case, my dear fellow, is as plain as a pike-staff, as the seeds are so very quickly killed by the sea-water. Seriously, it would be a curious experiment to try vitality in salt water of the plants which ought to be in Greenland. I forget, however, that it would be impossible, I suppose, to get hardly any except the Caltha, and if ever I stumble on that plant in seed I will try it.

I wish to Heaven some one would examine the rocks near sea-level at the south point of Greenland, and see if they are well scored; that would tell something. But then subsidence might have brought down higher rocks to present sea-level. I am much more willing to admit your Norwego-Greenland connecting land than most other cases, from the nature of the rocks in Spitzbergen and Bear Island. You have broached and thrown a lot of light on a splendid problem, which some day will be solved. It rejoices me to think that, when a boy, I was shown an erratic boulder in Shrewsbury, and was told by a clever old gentleman that till the world's end no one would ever guess how it came there.

It makes me laugh to think of Dr. Dawson's indignation at your sentence about "obliquity of vision." (358/1. See Letter 144.) By Jove, he will try and pitch into you some day. Good night for the present.