The most important point, as it seems to me, in the pamphlet is that on the morphological characters of plants, and I find I could not answer this without going into much detail.

The answer would be, as it seems to me, that important morphological characters, such as the position of the ovules and the relative position of the stamens to the ovarium (hypogynous, perigynous, etc.) are sometimes variable in the same species, as I incidentally mention when treating of the ray-florets in the Compositae and Umbelliferae; and I do not see how Nageli could maintain that differences in such characters prove an inherent tendency towards perfection. I see that I have forgotten to say that you have my fullest consent to append any discussion which you may think fit to the new edition. As for myself I cannot believe in spontaneous generation, and though I expect that at some future time the principle of life will be rendered intelligible, at present it seems to me beyond the confines of science.

LETTER 194. TO T.H. HUXLEY. Down, December 22nd [1866?].

I suppose that you have received Hackel's book (194/1. "Generelle Morphologie," 1866.) some time ago, as I have done. Whenever you have had time to read through some of it, enough to judge by, I shall be very curious to hear your judgment. I have been able to read a page or two here and there, and have been interested and instructed by parts. But my vague impression is that too much space is given to methodical details, and I can find hardly any facts or detailed new views. The number of new words, to a man like myself, weak in his Greek, is something dreadful. He seems to have a passion for defining, I daresay very well, and for coining new words. From my very vague notions on the book, and from its immense size, I should fear a translation was out of the question. I see he often quotes both of us with praise. I am sure I should like the book much, if I could read it straight off instead of groaning and swearing at each sentence. I have not yet had time to read your Physiology (194/2. "Lessons in Elementary Physiology," 1866.) book, except one chapter; but I have just re-read your book on "Man's Place, etc.," and I think I admire it more this second time even than the first. I doubt whether you will ever have time, but if ever you have, do read the chapter on hybridism in the new edition of the "Origin" (194/3. Fourth Edition (1866).), for I am very anxious to make you think less seriously on that difficulty. I have improved the chapter a good deal, I think, and have come to more definite views. Asa Gray and Fritz Muller (the latter especially) think that the new facts on illegitimate offspring of dimorphic plants, throw much indirect light on the subject. Now that I have worked up domestic animals, I am convinced of the truth of the Pallasian (194/4. See Letter 80.) view of loss of sterility under domestication, and this seems to me to explain much. But I had no intention, when I began this note, of running on at such length on hybridism; but you have been Objector-General on this head.

LETTER 195. TO T. RIVERS.

(195/1. For another letter of Mr. Darwin's to him see "Life and Letters," III., page 57.)

Down, December 23rd [1866?].

I do not know whether you will forgive a stranger addressing you. My name may possibly be known to you. I am now writing a book on the variation of animals and plants under domestication; and there is one little piece of information which it is more likely that you could give me than any man in the world, if you can spare half an hour from your professional labours, and are inclined to be so kind. I am collecting all accounts of what some call "sports," that is, of what I shall call "bud-variations," i.e. a moss-rose suddenly appearing on a Provence rose—a nectarine on a peach, etc. Now, what I want to know, and which is not likely to be recorded in print, is whether very slight differences, too slight to be worth propagating, thus appear suddenly by buds. As every one knows, in raising seedlings you may have every gradation from individuals identical with the parent, to slight varieties, to strongly marked varieties. Now, does this occur with buds or do only rather strongly marked varieties thus appear at rare intervals of time by buds? (195/2. Mr. Rivers could not give a decided answer, but he did not remember to have seen slight bud-variations. The question is discussed in "Variation under Domestication," Edition II., Volume I., page 443.) I should be most grateful for information. I may add that if you have observed in your enormous experience any remarkable "bud-variations," and could spare time to inform me, and allow me to quote them on your authority, it would be the greatest favour. I feel sure that these "bud-variations" are most interesting to any one endeavouring to make out what little can be made out on the obscure subject of variation.

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

I thank you much for your letter and the parcel of shoots. The case of the yellow plum is a treasure, and is now safely recorded on your authority in its proper place, in contrast with A. Knight's case of the yellow magnum bonum sporting into red. (196/1. See "Variation under Domestication," Edition II., Volume I., page 399.) I could see no difference in the shoots, except that those of the yellow were thicker, and I presume that this is merely accidental: as you do not mention it, I further presume that there are no further differences in leaves or flowers of the two plums. I am very glad to hear about the yellow ash, and that you yourself have seen the jessamine case. I must confess that I hardly fully believed in it; but now I do, and very surprising it is.

In an old French book, published in Amsterdam in 1786 (I think), there is an account, apparently authentic and attested by the writer as an eye-witness, of hyacinth bulbs of two colours being cut in two and grafted, and they sent up single stalks with differently coloured flowers on the two sides, and some flowers parti-coloured. I once thought of offering 5 pounds reward in the "Cottage Gardener" for such a plant; but perhaps it would seem too foolish. No instructions are given when to perform the operation; I have tried two or three times, and utterly failed. I find that I have a grand list of "bud-variations," and to-morrow shall work up such cases as I have about rose-sports, which seem very numerous, and which I see you state to occur comparatively frequently.

When a person is very good-natured he gets much pestered—a discovery which I daresay you have made, or anyhow will soon make; for I do want very much to know whether you have sown seed of any moss-roses, and whether the seedlings were moss-roses. (196/2. Moss-roses can be raised from seed ("Variation under Domestication," Edition II., Volume I., page 405.) Has a common rose produced by SEED a moss-rose?

If any light comes to you about very slight changes in the buds, pray have the kindness to illuminate me. I have cases of seven or eight varieties of the peach which have produced by "bud-variation" nectarines, and yet only one single case (in France) of a peach producing another closely similar peach (but later in ripening). How strange it is that a great change in the peach should occur not rarely and slighter changes apparently very rarely! How strange that no case seems recorded of new apples or pears or apricots by "bud-variation"! How ignorant we are! But with the many good observers now living our children's children will be less ignorant, and that is a comfort.

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

Very many thanks for your letter, which has told me exactly what I wanted to know. I shall give up all thoughts of trying to get the book (197/1. Hackel's "Generelle Morphologie," 1866. See "Life and Letters," III., pages 67, 68.) translated, for I am well convinced that it would be hopeless without too great an outlay. I much regret this, as I should think the work would be useful, and I am sure it would be to me, as I shall never be able to wade through more than here and there a page of the original. To all people I cannot but think that the number of new terms would be a great evil. I must write to him. I suppose you know his address, but in case you do not, it is "to care of Signor Nicolaus Krohn, Madeira." I have sent the MS. of my big book (197/2. "The Variation of Animals and Plants under Domestication," 1868.), and horridly, disgustingly big it will be, to the printers, but I do not suppose it will be published, owing to Murray's idea on seasons, till next November. I am thinking of a chapter on Man, as there has lately been so much said on Natural Selection in relation to man. I have not seen the Duke's (or Dukelet's? how can you speak so of a living real Duke?) book, but must get it from Mudie, as you say he attacks us. (197/3. "The Reign of Law" (1867), by the late Duke of Argyll. See "Life and Letters," III., page 65.)

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

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

I received some weeks ago your great work (198/1. "Generelle Morphologie," 1866.); I have read several parts, but I am too poor a German scholar and the book is too large for me to read it all. I cannot tell you how much I regret this, for I am sure that nearly the whole would interest me greatly, and I have already found several parts very useful, such as the discussion on cells and on the different forms of reproduction. I feel sure, after considering the subject deliberately and after consulting with Huxley, that it would be hopeless to endeavour to get a publisher to print an English translation; the work is too profound and too long for our English countrymen. The number of new terms would also, I am sure, tell much against its sale; and, indeed, I wish for my own sake that you had printed a glossary of all the new terms which you use. I fully expect that your book will be highly successful in Germany, and the manner in which you often refer to me in your text, and your dedication and the title, I shall always look at as one of the greatest honours conferred on me during my life. (198/2. As regards the dedication and title this seems a strong expression. The title is "Generelle Morphologie der Organismen. Allgemeine Grundzuge der organischen Formen-Wissenschaft mechanisch begrundet durch die von Charles Darwin reformirte Descendenz-Theorie." The dedication of the second volume is "Den Begrundern der Descendenz-Theorie, den denkenden Naturforschern, Charles Darwin, Wolfgang Goethe, Jean Lamarck widmet diese Grundzuge der Allgemeinen Entwickelungsgeschichte in vorzuglicher Verehrung, der Verfasser.")

I sincerely hope that you have had a prosperous expedition, and have met with many new and interesting animals. If you have spare time I should much like to hear what you have been doing and observing. As for myself, I have sent the MS. of my book on domestic animals, etc., to the printers. It turns out to be much too large; it will not be published, I suppose, until next November. I find that we have discussed several of the same subjects, and I think we agree on most points fairly well. I have lately heard several times from Fritz Muller, but he seems now chiefly to be working on plants. I often think of your visit to this house, which I enjoyed extremely, and it will ever be to me a real pleasure to remember our acquaintance. From what I heard in London I think you made many friends there. Shall you return through England? If so, and you can spare the time, we shall all be delighted to see you here again.

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

How rich and valuable a letter you have most kindly sent me! The case of Baronne Prevost (199/1. See "Variation under Domestication," Edition II., Volume I., page 406. Mr. Rivers had a new French rose with a delicate smooth stem, pale glaucous leaves and striped flesh-coloured flowers; on branches thus characterised there appeared "the famous old rose called 'Baronne Prevost,'" with its stout thorny stem and uniform rich-coloured double flowers.), with its different shoots, foliage, spines, and flowers, will be grand to quote. I am extremely glad to hear about the seedling moss-roses. That case of a seedling like a Scotch rose, unless you are sure that no Scotch rose grew near (and it is unlikely that you can remember), must, one would think, have been a cross.

I have little compunction for being so troublesome—not more than a grand Inquisitor has in torturing a heretic—for am I not doing a real good public service in screwing crumbs of knowledge out of your wealth of information?

P.S. Since the above was written I have read your paper in the "Gardeners' Chronicle": it is admirable, and will, I know, be a treasure to me. I did not at all know how strictly the character of so many flowers is inherited.

On my honour, when I began this note I had no thought of troubling you with a question; but you mention one point so interesting, and which I have had occasion to notice, that I must supplicate for a few more facts to quote on your authority. You say that you have one or two seedling peaches (199/2. "On raising Peaches, Nectarines, and other Fruits from Seed." By Thomas Rivers, Sawbridgeworth.—"Gard. Chron." 1866, page 731.) approaching very nearly to thick-fleshed almonds (I know about A. Knight and the Italian hybrid cases). Now, did any almond grow near your mother peach? But especially I want to know whether you remember what shape the stone was, whether flattened like that of an almond; this, botanically, seems the most important distinction. I earnestly wish to quote this. Was the flesh at all sweet?

Forgive if you can.

Have you kept these seedling peaches? if you would give me next summer a fruit, I want to have it engraved.

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

You are so kind as to offer to lend me Maillet's (200/1. For De Maillet see Mr. Huxley's review on "The Origin of Species" in the "Westminster Review," 1860, reprinted in "Lay Sermons," 1870, page 314. De Maillet's evolutionary views were published after his death in 1748 under the name of Telliamed (De Maillet spelt backwards).) work, which I have often heard of, but never seen. I should like to have a look at it, and would return it to you in a short time. I am bound to read it, as my former friend and present bitter enemy Owen generally ranks me and Maillet as a pair of equal fools.

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

You have done me a very great service in sending me the pages of the "Farmer." I do not know whether you wish it returned; but I will keep it unless I hear that you want it. Old I. Anderson-Henry passes a magnificent but rather absurd eulogium on me; but the point of such extreme value in my eyes is Mr. Traill's (201/1. Mr. Traill's results are given at page 420 of "Animals and Plants," Edition II., Volume I. In the "Life and Letters of G.J. Romanes," 1896, an interesting correspondence is published with Mr. Darwin on this subject. The plan of the experiments suggested to Romanes was to raise seedlings from graft-hybrids: if the seminal offspring of plants hybridised by grafting should show the hybrid character, it would be striking evidence in favour of pangenesis. The experiment, however, did not succeed.) statement that he made a mottled mongrel by cutting eyes through and joining two kinds of potatoes. (201/2. For an account of similar experiments now in progress, see a "Note on some Grafting Experiments" by R. Biffen in the "Annals of Botany," Volume XVI., page 174, 1902.) I have written to him for full information, and then I will set to work on a similar trial. It would prove, I think, to demonstration that propagation by buds and by the sexual elements are essentially the same process, as pangenesis in the most solemn manner declares to be the case.

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

We come up on Saturday, the 15th, for a week. I want much to see you for a short time to talk about my youngest boy and the School of Mines. I know it is rather unreasonable, but you must let me come a little after 10 o'clock on Sunday morning, the 16th. If in any way inconvenient, send me a line to "6, Queen Anne Street W.,"; but if I do not hear, I will (stomacho volente) call, but I will not stay very long and spoil your whole morning as a holiday. Will you turn two or three times in your mind this question: what I called "pangenesis" means that each cell throws off an atom of its contents or a gemmule, and that these aggregated form the true ovule or bud, etc.? Now I want to know whether I could not invent a better word. "Cyttarogenesis" (202/1. From kuttaros, a bee's-cell: cytogenesis would be a natural form of the word from kutos.)—i.e. cell-genesis—is more true and expressive, but long. "Atomogenesis" sounds rather better, I think, but an "atom" is an object which cannot be divided; and the term might refer to the origin of atoms of inorganic matter. I believe I like "pangenesis" best, though so indefinite; and though my wife says it sounds wicked, like pantheism; but I am so familiar now with this word, that I cannot judge. I supplicate you to help me.

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

I ordered the journal (203/1. "Quarterly Journal of Science," October, 1867, page 472. A review of the Duke of Argyll's "Reign of Law.") a long time ago, but by some oversight received it only yesterday, and read it. You will think my praise not worth having, from being so indiscriminate; but if I am to speak the truth, I must say I admire every word. You have just touched on the points which I particularly wished to see noticed. I am glad you had the courage to take up Angraecum (203/2. Angraecum sesquipedale, a Madagascan orchid, with a whiplike nectary, 11 to 12 inches in length, which, according to Darwin ("Fertilisation of Orchids," Edition II., page 163), is adapted to the visits of a moth with a proboscis of corresponding length. He points out that there is no difficulty in believing in the existence of such a moth as F. Muller has described ("Nature," 1873, page 223)—a Brazilian sphinx-moth with a trunk of 10 to 11 inches in length. Moreover, Forbes has given evidence to show that such an insect does exist in Madagascar ("Nature," VIII., 1873, page 121). The case of Angraecum was put forward by the Duke of Argyll as being necessarily due to the personal contrivance of the Deity. Mr. Wallace (page 476) shows that both proboscis and nectary might be increased in length by means of Natural Selection. It may be added that Hermann Muller has shown good grounds for believing that mutual specialisation of this kind is beneficial both to insect and plant.) after the Duke's attack; for I believe the principle in this case may be widely applied. I like the figure, but I wish the artist had drawn a better sphinx. With respect to beauty, your remarks on hideous objects and on flowers not being made beautiful except when of practical use to them, strike me as very good. On this one point of beauty I can hardly think that the Duke was quite candid. I have used in the concluding paragraph of my present book precisely the same argument as you have, even bringing in the bull-dog (203/3. "Variation of Animals and Plants," Edition I., Volume II., page 431: "Did He cause the frame and mental qualities of the dog to vary in order that a breed might be formed of indomitable ferocity, with jaws fitted to pin down the bull for man's brutal sport?"), with respect to variations not having been specially ordained. Your metaphor of the river (203/4. See Wallace, op. cit., pages 477-8. He imagines an observer examining a great river-system, and finding everywhere adaptations which reveal the design of the Creator. "He would see special adaptation to the wants of man in broad, quiet, navigable rivers, through fertile alluvial plains that would support a large population, while the rocky streams and mountain torrents were confined to those sterile regions suitable only for a small population of shepherds and herdsmen.') is new to me, and admirable; but your other metaphor, in which you compare classification and complex machines, does not seem to me quite appropriate, though I cannot point out what seems deficient. The point which seems to me strong is that all naturalists admit that there is a natural classification, and it is this which descent explains. I wish you had insisted a little more against the "North British" (203/5. At page 485 Mr. Wallace deals with Fleeming Jenkin's review in the "North British Review," 1867. The review strives to show that there are strict limits to variation, since the most rigorous and long-continued selection does not indefinitely increase such a quality as the fleetness of a racehorse. On this Mr. Wallace remarks that "this argument fails to meet the real question," which is, not whether indefinite change is possible, "but whether such differences as do occur in nature could have been produced by the accumulation of variations by selection.") on the reviewer assuming that each variation which appears is a strongly marked one; though by implication you have made this very plain. Nothing in your whole article has struck me more than your view with respect to the limit of fleetness in the racehorse and other such cases: I shall try and quote you on this head in the proof of my concluding chapter. I quite missed this explanation, though in the case of wheat I hit upon something analogous. I am glad you praise the Duke's book, for I was much struck with it. The part about flight seemed to me at first very good; but as the wing is articulated by a ball-and-socket joint, I suspect the Duke would find it very difficult to give any reason against the belief that the wing strikes the air more or less obliquely. I have been very glad to see your article and the drawing of the butterfly in "Science Gossip." By the way, I cannot but think that you push protection too far in some cases, as with the stripes on the tiger. I have also this morning read an excellent abstract in the "Gardeners' Chronicle" of your paper on nests. (203/6. An abstract of a paper on "Birds' Nests and Plumage," read before the British Association: see "Gard. Chron." 1867, page 1047.) I was not by any means fully converted by your letter, but I think now I am so; and I hope it will be published somewhere in extenso. It strikes me as a capital generalisation, and appears to me even more original than it did at first...

I have finished Volume I. of my book ["Variation of Animals and Plants"], and I hope the whole will be out by the end of November. If you have the patience to read it through, which is very doubtful, you will find, I think, a large accumulation of facts which will be of service to you in future papers; and they could not be put to better use, for you certainly are a master in the noble art of reasoning.

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

I know you have no time for speculative correspondence; and I did not in the least expect an answer to my last. But I am very glad to have had it, for in my eclectic work the opinions of the few good men are of great value to me.

I knew, of course, of the Cuvierian view of classification (204/1. Cuvier proved that "animals cannot be arranged in a single series, but that there are several distinct plans of organisation to be observed among them, no one of which, in its highest and most complicated modification, leads to any of the others" (Huxley's "Darwiniana," page 215).); but I think that most naturalists look for something further, and search for "the natural system,"—"for the plan on which the Creator has worked," etc., etc. It is this further element which I believe to be simply genealogical.

But I should be very glad to have your answer (either when we meet or by note) to the following case, taken by itself, and not allowing yourself to look any further than to the point in question. Grant all races of man descended from one race—grant that all the structure of each race of man were perfectly known—grant that a perfect table of the descent of each race was perfectly known—grant all this, and then do you not think that most would prefer as the best classification, a genealogical one, even if it did occasionally put one race not quite so near to another, as it would have stood, if collocated by structure alone? Generally, we may safely presume, that the resemblance of races and their pedigrees would go together.

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

It might be asked why is development so all-potent in classification, as I fully admit it is? I believe it is because it depends on, and best betrays, genealogical descent; but this is too large a point to enter on.

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

I send by this post the article in the Victorian Institute with respect to frogs' spawn. If you remember in your boyhood having ever tried to take a small portion out of the water, you will remember that it is most difficult. I believe all the birds in the world might alight every day on the spawn of batrachians, and never transport a single ovum. With respect to the young of molluscs, undoubtedly if the bird to which they were attached alighted on the sea, they would be instantly killed; but a land-bird would, I should think, never alight except under dire necessity from fatigue. This, however, has been observed near Heligoland (205/1. Instances are recorded by Gatke in his "Heligoland as an Ornithological Observatory" (translated by Rudolph Rosenstock, Edinburgh, 1895) of land-birds, such as thrushes, buntings, finches, etc., resting for a short time on the surface of the water. The author describes observations made by himself about two miles west of Heligoland (page 129).); and land-birds, after resting for a time on the tranquil sea, have been seen to rise and continue their flight. I cannot give you the reference about Heligoland without much searching. This alighting on the sea may aid you in your unexpected difficulty of the too-easy diffusion of land-molluscs by the agency of birds. I much enjoyed my morning's talk with you.

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

I thank you for your letter, which has quite delighted me. I sincerely congratulate you on your success in making a graft-hybrid (206/1. Prof. Hildebrand's paper is in the "Bot. Zeitung," 1868: the substance is given in "Variation of Animals and Plants," Edition II., Volume I., page 420.), for I believe it to be a most important observation. I trust that you will publish full details on this subject and on the direct action of pollen (206/2. See Prof. Hildebrand, "Bot. Zeitung," 1868, and "Variation of Animals and Plants," Edition II., Volume I., page 430. A yellow-grained maize was fertilised with pollen from a brown-grained one; the result was that ears were produced bearing both yellow and dark-coloured grains.): I hope that you will be so kind as to send me a copy of your paper. If I had succeeded in making a graft-hybrid of the potato, I had intended to raise seedlings from the graft-hybrid and from the two parent-forms (excluding insects) and carefully compare the offspring. This, however, would be difficult on account of the sterility and variability of the potato. When in the course of a few months you receive my second volume (206/3. This sentence may be paraphrased—"When you receive my book and read the second volume."), you will see why I think these two subjects so important. They have led me to form a hypothesis on the various forms of reproduction, development, inheritance, etc., which hypothesis, I believe, will ultimately be accepted, though how it will be now received I am very doubtful.

Once again I congratulate you on your success.

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

Many thanks about names of plants, synonyms, and male flowers—all that I wanted.

I have been glad to see Watson's letter, and am sorry he is a renegade about Natural Selection. It is, as you say, characteristic, with the final fling at you.

His difficulty about the difference between the two genera of St. Helena Umbellifers is exactly the same as what Nageli has urged in an able pamphlet (207/1. "Ueber Entstehung und Begriff der naturhist. Art." "Sitz. der K. Bayer. Akad. Der Wiss. zu Munchen," 1865. Some of Nageli's points are discussed in the "Origin," Edition V., page 151.), and who in consequence maintains that there is some unknown innate tendency to progression in all organisms. I said in a letter to him that of course I could not in the least explain such cases; but that they did not seem to me of overwhelming force, as long as we are quite ignorant of the meaning of such structures, whether they are of any service to the plants, or inevitable consequences of modifications in other parts.

I cannot understand what Watson means by the "counter-balance in nature" to divergent variation. There is the counterbalance of crossing, of which my present work daily leads me to see more and more the efficiency; but I suppose he means something very different. Further, I believe variation to be divergent solely because diversified forms can best subsist. But you will think me a bore.

I enclose half a letter from F. Muller (which please return) for the chance of your liking to see it; though I have doubted much about sending it, as you are so overworked. I imagine the Solanum-like flower is curious.

I heard yesterday to my joy that Dr. Hildebrand has been experimenting on the direct action of pollen on the mother-plant with success. He has also succeeded in making a true graft-hybrid between two varieties of potatoes, in which I failed. I look at this as splendid for pangenesis, as being strong evidence that bud-reproduction and seminal reproduction do not essentially differ.

My book is horribly delayed, owing to the accursed index-maker. (207/2. Darwin thoroughly appreciated the good work put into the index of "The Variation of Animals and Plants.") I have almost forgotten it!

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

Most sincere thanks for your kind congratulations. I never received a note from you in my life without pleasure; but whether this will be so after you have read pangenesis (208/1. In Volume II. of "Animals and Plants, 1868.), I am very doubtful. Oh Lord, what a blowing up I may receive! I write now partly to say that you must not think of looking at my book till the summer, when I hope you will read pangenesis, for I care for your opinion on such a subject more than for that of any other man in Europe. You are so terribly sharp-sighted and so confoundedly honest! But to the day of my death I will always maintain that you have been too sharp-sighted on hybridism; and the chapter on the subject in my book I should like you to read: not that, as I fear, it will produce any good effect, and be hanged to you.

I rejoice that your children are all pretty well. Give Mrs. Huxley the enclosed (208/2. Queries on Expression.), and ask her to look out when one of her children is struggling and just going to burst out crying. A dear young lady near here plagued a very young child for my sake, till it cried, and saw the eyebrows for a second or two beautifully oblique, just before the torrent of tears began.

The sympathy of all our friends about George's success (it is the young Herald) (208/3. His son George was Second Wrangler in 1868; as a boy he was an enthusiast in heraldry.) has been a wonderful pleasure to us. George has not slaved himself, which makes his success the more satisfactory. Farewell, my dear Huxley, and do not kill yourself with work.

(209/1. The following group of letters deals with the problem of the causes of the sterility of hybrids. Mr. Darwin's final view is given in the "Origin," sixth edition (page 384, edition 1900). He acknowledges that it would be advantageous to two incipient species, if by physiological isolation due to mutual sterility, they could be kept from blending: but he continues, "After mature reflection it seems to me that this could not have been effected through Natural Selection." And finally he concludes (page 386):—

"But it would be superfluous to discuss this question in detail; for with plants we have conclusive evidence that the sterility of crossed species must be due to some principle quite independent of Natural Selection. Both Gartner and Kolreuter have proved that in genera including numerous species, a series can be formed from species which when crossed yield fewer and fewer seeds, to species which never produce a single seed, but yet are affected by the pollen of certain other species, for the germen swells. It is here manifestly impossible to select the more sterile individuals, which have already ceased to yield seeds; so that this acme of sterility, when the germen alone is affected, cannot have been gained through selection; and from the laws governing the various grades of sterility being so uniform throughout the animal and vegetable kingdoms, we may infer that the cause, whatever it may be, is the same or nearly the same in all cases."

Mr. Wallace, on the other hand, still adheres to his view: see his "Darwinism," 1889, page 174, and for a more recent statement see page 292, note 1, Letter 211, and page 299.

The discussion of 1868 began with a letter from Mr. Wallace, written towards the end of February, giving his opinion on the "Variation of Animals and Plants;" the discussion on the sterility of hybrids is at page 185, Volume II., of the first edition.)

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

The only parts I have yet met with where I somewhat differ from your views, are in the chapter on the causes of variability, in which I think several of your arguments are unsound: but this is too long a subject to go into now. Also, I do not see your objection to sterility between allied species having been aided by Natural Selection. It appears to me that, given a differentiation of a species into two forms, each of which was adapted to a special sphere of existence, every slight degree of sterility would be a positive advantage, not to the individuals who were sterile, but to each form. If you work it out, and suppose the two incipient species a...b to be divided into two groups, one of which contains those which are fertile when the two are crossed, the other being slightly sterile, you will find that the latter will certainly supplant the former in the struggle for existence; remembering that you have shown that in such a cross the offspring would be more vigorous than the pure breed, and therefore would certainly soon supplant them, and as these would not be so well adapted to any special sphere of existence as the pure species a and b, they would certainly in their turn give way to a and b.

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

I shall be very glad to hear, at some future day, your criticisms on the "causes of variability." Indeed, I feel sure that I am right about sterility and Natural Selection. Two of my grown-up children who are acute reasoners have two or three times at intervals tried to prove me wrong; and when your letter came they had another try, but ended by coming back to my side. I do not quite understand your case, and we think that a word or two is misplaced. I wish some time you would consider the case under the following point of view. If sterility is caused or accumulated through Natural Selection, then, as every degree exists up to absolute barrenness, Natural Selection must have the power of increasing it. Now take two species A and B, and assume that they are (by any means) half-sterile, i.e., produce half the full number of offspring. Now try and make (by Natural Selection) A and B absolutely sterile when crossed, and you will find how difficult it is. I grant, indeed it is certain, that the degree of the sterility of the individuals of A and B will vary; but any such extra-sterile individuals of, we will say A, if they should hereafter breed with other individuals of A, will bequeath no advantage to their progeny, by which these families will tend to increase in number over other families of A, which are not more sterile when crossed with B. But I do not know that I have made this any clearer than in the chapter in my book. It is a most difficult bit of reasoning, which I have gone over and over again on paper with diagrams. (210/1. This letter appeared in "Life and Letters," III., page 80.)

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

I beg to enclose what appears to me a demonstration on your own principles, that Natural Selection could produce sterility of hybrids. If it does not convince you, I shall be glad if you will point out where the fallacy lies. I have taken the two cases of a slight sterility overcoming perfect fertility, and of a perfect sterility overcoming a partial fertility,—the beginning and end of the process. You admit that variations in fertility and sterility occur, and I think you will also admit that if I demonstrate that a considerable amount of sterility would be advantageous to a variety, that is sufficient proof that the slightest variation in that direction would be useful also, and would go on accumulating.

1. Let there be a species which has varied into two forms, each adapted to existing conditions (211/1. "Existing conditions," means of course new conditions which have now come into existence. And the "two" being both better adapted than the parent form, means that they are better adapted each to a special environment in the same area—as one to damp, another to dry places; one to woods, another to open grounds, etc., etc., as Darwin had already explained. A.R.W. (1899).) better than the parent form, which they supplant.

2. If these two forms, which are supposed to co-exist in the same district, do not intercross, Natural Selection will accumulate favourable variations, till they become sufficiently well adapted to their conditions of life and form two allied species.

3. But if these two forms freely intercross with each other and produce hybrids which are also quite fertile inter se, then the formation of the two distinct races or species will be retarded or perhaps entirely prevented; for the offspring of the crossed unions will be more vigorous owing to the cross, although less adapted to their conditions of life than either of the pure breeds. (211/2. After "pure breeds," add "because less specialised." A.R.W. (1899).)

4. Now let a partial sterility of some individuals of these two forms arise when they intercross; and as this would probably be due to some special conditions of life, we may fairly suppose it to arise in some definite portion of the area occupied by the two forms.

5. The result is that in this area hybrids will not increase so rapidly as before; and as by the terms of the problem the two pure forms are better suited to the conditions of life than the hybrids, they will tend to supplant the latter altogether whenever the struggle for existence becomes severe.

6. We may fairly suppose, also, that as soon as any sterility appears under natural conditions, it will be accompanied by some disinclination to cross-unions; and this will further diminish the production of hybrids.

7. In the other part of the area, however, where hybridism occurs unchecked, hybrids of various degrees will soon far outnumber the parent or pure form.

8. The first result, then, of a partial sterility of crosses appearing in one part of the area occupied by the two forms, will be, that the GREAT MAJORITY of the individuals will there consist of the pure forms only, while in the rest of the area these will be in a minority,—which is the same as saying, that the new sterile or physiological variety of the two forms will be better suited to the conditions of existence than the remaining portion which has not varied physiologically.

9. But when the struggle for existence becomes severe, that variety which is best adapted to the conditions of existence always supplants that which is imperfectly adapted; therefore by Natural Selection the sterile varieties of the two forms will become established as the only ones.

10. Now let a fresh series of variations in the amount of sterility and in the disinclination to crossed unions occur,—also in certain parts of the area: exactly the same result must recur, and the progeny of this new physiological variety again in time occupy the whole area.

11. There is yet another consideration that supports this view. It seems probable that the variations in amount of sterility would to some extent concur with and perhaps depend upon the structural variations; so that just in proportion as the two forms diverged and became better adapted to the conditions of existence, their sterility would increase. If this were the case, then Natural Selection would act with double strength, and those varieties which were better adapted to survive both structurally and physiologically, would certainly do so. (211/3. The preceding eleven paragraphs are substantially but not verbally identical with the statement of the argument in Mr. Wallace's "Darwinism," 1889. Pages 179, 180, note 1.)

12. Let us now consider the more difficult case of two allied species A, B, in the same area, half the individuals of each (As, Bs) being absolutely sterile, the other half (Af, Bf) being partially fertile: will As, Bs ultimately exterminate Af, Bf?

13. To avoid complication, it must be granted, that between As and Bs no cross-unions take place, while between Af and Bf cross-unions are as frequent as direct unions, though much less fertile. We must also leave out of consideration crosses between As and Af, Bs and Bf, with their various approaches to sterility, as I believe they will not affect the final result, although they will greatly complicate the problem.

14. In the first generation there will result: 1st, The pure progeny of As and Bs; 2nd, The pure progeny of Af and of Bf; and 3rd, The hybrid progeny of Af, Bf.

15. Supposing that, in ordinary years, the increased constitutional vigour of the hybrids exactly counterbalances their imperfect adaptations to conditions, there will be in the second generation, besides these three classes, hybrids of the second degree between the first hybrids and Af and Bf respectively. In succeeding generations there will be hybrids of all degrees, varying between the first hybrids and the almost pure types of Af and Bf.

16. Now, if at first the number of individuals of As, Bs, Af and Bf were equal, and year after year the total number continues stationary, I think it can be proved that, while half will be the pure progeny of As and Bs, the other half will become more and more hybridised, until the whole will be hybrids of various degrees.

17. Now, this hybrid and somewhat intermediate race cannot be so well adapted to the conditions of life as the two pure species, which have been formed by the minute adaptation to conditions through Natural Selection; therefore, in a severe struggle for existence, the hybrids must succumb, especially as, by hypothesis, their fertility would not be so great as that of the two pure species.

18. If we were to take into consideration the unions of As with Af and Bs with Bf, the results would become very complicated, but it must still lead to there being a number of pure forms entirely derived from As and Bs, and of hybrid forms mainly derived from Af and Bf; and the result of the struggle of these two sets of individuals cannot be doubtful.

19. If these arguments are sound, it follows that sterility may be accumulated and increased, and finally made complete by Natural Selection, whether the sterile varieties originate together in a definite portion of the area occupied by the two species, or occur scattered over the whole area. (211/4. The first part of this discussion should be considered alone, as it is both more simple and more important. I now believe that the utility, and therefore the cause of sterility between species, is during the process of differentiation. When species are fully formed, the occasional occurrence of hybrids is of comparatively small importance, and can never be a danger to the existence of the species. A.R.W. (1899).)

P.S.—In answer to the objection as to the unequal sterility of reciprocal crosses ("Variation, etc." Volume II., page 186) I reply that, as far as it went, the sterility of one cross would be advantageous even if the other cross was fertile: and just as characters now co-ordinated may have been separately accumulated by Natural Selection, so the reciprocal crosses may have become sterile one at a time.

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

(212/1. Mr. Darwin had already written a short note to Mr. Wallace expressing a general dissent from his view.)

I do not feel that I shall grapple with the sterility argument till my return home; I have tried once or twice, and it has made my stomach feel as if it had been placed in a vice. Your paper has driven three of my children half mad—one sat up till 12 o'clock over it. My second son, the mathematician, thinks that you have omitted one almost inevitable deduction which apparently would modify the result. He has written out what he thinks, but I have not tried fully to understand him. I suppose that you do not care enough about the subject to like to see what he has written.

LETTER 212A. A.R. WALLACE TO CHARLES DARWIN. Hurstpierpoint, March, 24th [1868].

I return your son's notes with my notes on them. Without going into any details, is not this a strong general argument?

1. A species varies occasionally in two directions, but owing to their free intercrossing the varieties never increase.

2. A change of conditions occurs which threatens the existence of the species; but the two varieties are adapted to the changing conditions, and if accumulated will form two new species adapted to the new conditions.

3. Free crossing, however, renders this impossible, and so the species is in danger of extinction.

4. If sterility would be induced, then the pure races would increase more rapidly, and replace the old species.

5. It is admitted that partial sterility between varieties does occasionally occur. It is admitted [that] the degree of this sterility varies; is it not probable that Natural Selection can accumulate these variations, and thus save the species? If Natural Selection can NOT do this, how do species ever arise, except when a variety is isolated?

Closely allied species in distinct countries being sterile is no difficulty; for either they diverged from a common ancestor in contact, and Natural Selection increased the sterility, or they were isolated, and have varied since: in which case they have been for ages influenced by distinct conditions which may well produce sterility.

If the difficulty of grafting was as great as the difficulty of crossing, and as regular, I admit it would be a most serious objection. But it is not. I believe many distinct species can be grafted, while others less distinct cannot. The regularity with which natural species are sterile together, even when very much alike, I think is an argument in favour of the sterility having been generally produced by Natural Selection for the good of the species.

The other difficulty, of unequal sterility of reciprocal crosses, seems none to me; for it is a step to more complete sterility, and as such would be increased by selection.

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

I have been considering the terrible problem. Let me first say that no man could have more earnestly wished for the success of Natural Selection in regard to sterility than I did; and when I considered a general statement (as in your last note) I always felt sure it could be worked out, but always failed in detail. The cause being, as I believe, that Natural Selection cannot effect what is not good for the individual, including in this term a social community. It would take a volume to discuss all the points, and nothing is so humiliating to me as to agree with a man like you (or Hooker) on the premises and disagree about the result.

I agree with my son's argument and not with the rejoinder. The cause of our difference, I think, is that I look at the number of offspring as an important element (all circumstances remaining the same) in keeping up the average number of individuals within any area. I do not believe that the amount of food by any means is the sole determining cause of number. Lessened fertility is equivalent to a new source of destruction. I believe if in one district a species produced from any cause fewer young, the deficiency would be supplied from surrounding districts. This applies to your Paragraph 5. (213/1. See Letter 211.) If the species produced fewer young from any cause in every district, it would become extinct unless its fertility were augmented through Natural Selection (see H. Spencer).

I demur to probability and almost to possibility of Paragraph 1., as you start with two forms within the same area, which are not mutually sterile, and which yet have supplanted the parent-form.

(Paragraph 6.) I know of no ghost of a fact supporting belief that disinclination to cross accompanies sterility. It cannot hold with plants, or the lower fixed aquatic animals. I saw clearly what an immense aid this would be, but gave it up. Disinclination to cross seems to have been independently acquired, probably by Natural Selection; and I do not see why it would not have sufficed to have prevented incipient species from blending to have simply increased sexual disinclination to cross.

(Paragraph 11.) I demur to a certain extent to amount of sterility and structural dissimilarity necessarily going together, except indirectly and by no means strictly. Look at vars. of pigeons, fowls, and cabbages.

I overlooked the advantage of the half-sterility of reciprocal crosses; yet, perhaps from novelty, I do not feel inclined to admit probability of Natural Selection having done its work so queerly.

I will not discuss the second case of utter sterility, but your assumptions in Paragraph 13 seem to me much too complicated. I cannot believe so universal an attribute as utter sterility between remote species was acquired in so complex a manner. I do not agree with your rejoinder on grafting: I fully admit that it is not so closely restricted as crossing, but this does not seem to me to weaken the case as one of analogy. The incapacity of grafting is likewise an invariable attribute of plants sufficiently remote from each other, and sometimes of plants pretty closely allied.

The difficulty of increasing the sterility through Natural Selection of two already sterile species seems to me best brought home by considering an actual case. The cowslip and primrose are moderately sterile, yet occasionally produce hybrids. Now these hybrids, two or three or a dozen in a whole parish, occupy ground which might have been occupied by either pure species, and no doubt the latter suffer to this small extent. But can you conceive that any individual plants of the primrose and cowslip which happened to be mutually rather more sterile (i.e. which, when crossed, yielded a few less seed) than usual, would profit to such a degree as to increase in number to the ultimate exclusion of the present primrose and cowslip? I cannot.

My son, I am sorry to say, cannot see the full force of your rejoinder in regard to second head of continually augmented sterility. You speak in this rejoinder, and in Paragraph 5, of all the individuals becoming in some slight degree sterile in certain districts: if you were to admit that by continued exposure to these same conditions the sterility would inevitably increase, there would be no need of Natural Selection. But I suspect that the sterility is not caused so much by any particular conditions as by long habituation to conditions of any kind. To speak according to pangenesis, the gemmules of hybrids are not injured, for hybrids propagate freely by buds; but their reproductive organs are somehow affected, so that they cannot accumulate the proper gemmules, in nearly the same manner as the reproductive organs of a pure species become affected when exposed to unnatural conditions.

This is a very ill-expressed and ill-written letter. Do not answer it, unless the spirit urges you. Life is too short for so long a discussion. We shall, I greatly fear, never agree.

LETTER 214. A.R. WALLACE TO CHARLES DARWIN. Hurstpierpoint, [April?] 8th, 1868.

I am sorry you should have given yourself the trouble to answer my ideas on sterility. If you are not convinced, I have little doubt but that I am wrong; and, in fact, I was only half convinced by my own arguments, and I now think there is about an even chance that Natural Selection may or may not be able to accumulate sterility. If my first proposition is modified to the existence of a species and a variety in the same area, it will do just as well for my argument. Such certainly do exist. They are fertile together, and yet each maintains itself tolerably distinct. How can this be, if there is no disinclination to crossing?

My belief certainly is that number of offspring is not so important an element in keeping up population of a species as supply of food and other favourable conditions; because the numbers of a species constantly vary greatly in different parts of its own area, whereas the average number of offspring is not a very variable element.

However, I will say no more, but leave the problem as insoluble, only fearing that it will become a formidable weapon in the hands of the enemies of Natural Selection.

LETTER 215. TO J.D. HOOKER.

(215/1. The following extract from a letter to Sir Joseph Hooker (dated April 3rd, 1868) refers to his Presidential Address for the approaching meeting of the British Association at Norwich.

Some account of Sir Joseph's success is given in the "Life and Letters," III., page 100, also in Huxley's "Life," Volume I., page 297, where Huxley writes to Darwin:—

"We had a capital meeting at Norwich, and dear old Hooker came out in great force, as he always does in emergencies. The only fault was the terrible 'Darwinismus' which spread over the section and crept out when you least expected it, even in Fergusson's lecture on 'Buddhist Temples.' You will have the rare happiness to see your ideas triumphant during your lifetime.

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

Down, April 3rd [1868].

I have been thinking over your Presidential Address; I declare I made myself quite uncomfortable by fancying I had to do it, and feeling myself utterly dumbfounded.

But I do not believe that you will find it so difficult. When you come to Down I shall be very curious to hear what your ideas are on the subject.

Could you make anything out of a history of the great steps in the progress of Botany, as representing the whole of Natural History? Heaven protect you! I suppose there are men to whom such a job would not be so awful as it appears to me...If you had time, you ought to read an article by W. Bagehot in the April number of the "Fortnightly" (215/2. "Physic and Politics," "Fortnightly Review," Volume III., page 452, 1868.), applying Natural Selection to early or prehistoric politics, and, indeed, to late politics,—this you know is your view.

LETTER 216. A.R. WALLACE TO CHARLES DARWIN. 9, St. Mark's Crescent, N.W., August 16th [1868].

I ought to have written before to thank you for the copies of your papers on Primula and on "Cross-unions of Dimorphic Plants, etc." The latter is particularly interesting and the conclusion most important; but I think it makes the difficulty of how these forms, with their varying degrees of sterility, originated, greater than ever. If "natural selection" could not accumulate varying degrees of sterility for the plant's benefit, then how did sterility ever come to be associated with one cross of a trimorphic plant rather than another? The difficulty seems to be increased by the consideration that the advantage of a cross with a distinct individual is gained just as well by illegitimate as by legitimate unions. By what means, then, did illegitimate unions ever become sterile? It would seem a far simpler way for each plant's pollen to have acquired a prepotency on another individual's stigma over that of the same individual, without the extraordinary complication of three differences of structure and eighteen different unions with varying degrees of sterility!

However, the fact remains an excellent answer to the statement that sterility of hybrids proves the absolute distinctness of the parents.

I have been reading with great pleasure Mr. Bentham's last admirable address (216/1. "Proc. Linn. Soc." 1867-8, page lvii.), in which he so well replies to the gross misstatements of the "Athenaeum;" and also says award in favour of pangenesis. I think we may now congratulate you on having made a valuable convert, whose opinions on the subject, coming so late and being evidently so well considered, will have much weight.

I am going to Norwich on Tuesday to hear Dr. Hooker, who I hope will boldly promulgate "Darwinism" in his address. (216/2. Sir Joseph Hooker's Presidential Address at the British Association Meeting.) Shall we have the pleasure of seeing you there?

I am engaged in negociations about my book.

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

(216/3. We are permitted by Mr. Wallace to append the following note as to his more recent views on the question of Natural Selection and sterility:—

"When writing my "Darwinism," and coming again to the consideration of this problem of the effect of Natural Selection in accumulating variations in the amount of sterility between varieties or incipient species twenty years later, I became more convinced, than I was when discussing with Darwin, of the substantial accuracy of my argument. Recently a correspondent who is both a naturalist and a mathematician has pointed out to me a slight error in my calculation at page 183 (which does not, however, materially affect the result), disproving the 'physiological selection' of the late Dr. Romanes, but he can see no fallacy in my argument as to the power of Natural Selection to increase sterility between incipient species, nor, so far as I am aware, has any one shown such fallacy to exist.

"On the other points on which I differed from Mr. Darwin in the foregoing discussion—the effect of high fertility on population of a species, etc.—I still hold the views I then expressed, but it would be out of place to attempt to justify them here."

A.R.W. (1899).)

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

With respect to the points in your note, I may sometimes have expressed myself with ambiguity. At the end of Chapter XXIII., where I say that marked races are not often (you omit "often") produced by changed conditions (217/1. "Hence, although it must be admitted that new conditions of life do sometimes definitely affect organic beings, it may be doubted whether well-marked races have often been produced by the direct action of changed conditions without the aid of selection either by man or nature." ("Animals and Plants," Volume II., page 292, 1868.)), I intended to refer to the direct action of such conditions in causing variation, and not as leading to the preservation or destruction of certain forms. There is as wide a difference in these two respects as between voluntary selection by man and the causes which induce variability. I have somewhere in my book referred to the close connection between Natural Selection and the action of external conditions in the sense which you specify in your note. And in this sense all Natural Selection may be said to depend on changed conditions. In the "Origin" I think I have underrated (and from the cause which you mention) the effects of the direct action of external conditions in producing varieties; but I hope in Chapter XXIII. I have struck as fair a balance as our knowledge permits.

It is wonderful to me that you have patience to read my slips, and I cannot but regret, as they are so imperfect; they must, I think, give you a wrong impression, and had I sternly refused, you would perhaps have thought better of my book. Every single slip is greatly altered, and I hope improved.

With respect to the human ovule, I cannot find dimensions given, though I have often seen the statement. My impression is that it would be just or barely visible if placed on a clear piece of glass. Huxley could answer your question at once.

I have not been well of late, and have made slow progress, but I think my book will be finished by the middle of November.

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

I am in the second volume of your book, and I have been astonished at the immense number of interesting facts you have brought together. I read the chapter on pangenesis first, for I could not wait. I can hardly tell you how much I admire it. It is a positive comfort to me to have any feasible explanation of a difficulty that has always been haunting me, and I shall never be able to give it up till a better one supplies its place,—and that I think hardly possible. You have now fairly beaten Spencer on his own ground, for he really offered no solution of the difficulties of the problem. The incomprehensible minuteness and vast numbers of the physiological germs or atoms (which themselves must be compounded of numbers of Spencer's physiological units) is the only difficulty; but that is only on a par with the difficulties in all conceptions of matter, space, motion, force, etc.

As I understood Spencer, his physiological units were identical throughout each species, but slightly different in each different species; but no attempt was made to show how the identical form of the parent or ancestors came to be built up of such units.

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

You cannot well imagine how much I have been pleased by what you say about pangenesis. None of my friends will speak out, except to a certain extent Sir H. Holland, who found it very tough reading, but admits that some view "closely akin to it" will have to be admitted. Hooker, as far as I understand him, which I hardly do at present, seems to think that the hypothesis is little more than saying that organisms have such and such potentialities. What you say exactly and fully expresses my feelings—viz., that it is a relief to have some feasible explanation of the various facts, which can be given up as soon as any better hypothesis is found. It has certainly been an immense relief to my mind; for I have been stumbling over the subject for years, dimly seeing that some relation existed between the various classes of facts. I now hear from H. Spencer that his views quoted in my footnote refer to something quite distinct, as you seem to have perceived. (219/1. This letter is published in "Life and Letters," III., page 79.)

LETTER 220. A.R. WALLACE TO CHARLES DARWIN. Hurstpierpoint, March 1st, 1868.

...Sir C. Lyell spoke to me as if he has greatly admired pangenesis. I am very glad H. Spencer at once acknowledges that his view was something quite distinct from yours. Although, as you know, I am a great admirer of his, I feel how completely his view failed to go to the root of the matter, as yours does. His explained nothing, though he was evidently struggling hard to find an explanation. Yours, as far as I can see, explains everything in growth and reproduction—though, of course, the mystery of life and consciousness remains as great as ever.

Parts of the chapter on pangenesis I found hard reading, and have not quite mastered yet, and there are also throughout the discussions in Volume II. many bits of hard reading, on minute points which we, who have not worked experimentally at cultivation and crossing, as you have done, can hardly see the importance of, or their bearing on the general question.

If I am asked, I may perhaps write an article on the book for some periodical, and, if so, shall do what I can to make "Pangenesis" appreciated...

(220/1. In "Nature," May 25th, 1871, page 69, appeared a letter on pangenesis from Mr. A.C. Ranyard, dealing with the difficulty that the "sexual elements produced upon the scion" have not been shown to be affected by the stock. Mr. Darwin, in an annotated copy of this letter, disputes the accuracy of the statement, but adds: "THE BEST OBJECTION YET RAISED." He seems not to have used Mr. Ranyard's remarks in the 2nd edition of the "Variation of Animals and Plants," 1875.)

LETTER 221. TO J.D. HOOKER. Down, May 21st [1868].

I know that you have been overworking yourself, and that makes you think that you are doing nothing in science. If this is the case (which I do not believe), your intellect has all run to letter-writing, for I never in all my life received a pleasanter one than your last. It greatly amused us all. How dreadfully severe you are on the Duke (221/1. The late Duke of Argyll, whose "Reign of Law" Sir J.D. Hooker had been reading.): I really think too severe, but then I am no fair judge, for a Duke, in my eyes, is no common mortal, and not to be judged by common rules! I pity you from the bottom of my soul about the address (221/2. Sir Joseph was President of the British Association at Norwich in 1868: see "Life and Letters," III., page 100. The reference to "Insular Floras" is to Sir Joseph's lecture at the Nottingham meeting of the British Association in 1866: see "Life and Letters," III., page 47.): it makes my flesh creep; but when I pitied you to Huxley, he would not join at all, and would only say that you did and delivered your Insular Flora lecture so admirably in every way that he would not bestow any pity on you. He felt certain that you would keep your head high up. Nevertheless, I wish to God it was all over for your sake. I think, from several long talks, that Huxley will give an excellent and original lecture on Geograph. Distrib. of birds. I have been working very hard—too hard of late—on Sexual Selection, which turns out a gigantic subject; and almost every day new subjects turn up requiring investigation and leading to endless letters and searches through books. I am bothered, also, with heaps of foolish letters on all sorts of subjects, but I am much interested in my subject, and sometimes see gleams of light. All my other letters have prevented me indulging myself in writing to you; but I suddenly found the locust grass (221/3. No doubt the plants raised from seeds taken from locust dung sent by Mr. Weale from South Africa. The case is mentioned in the fifth edition of the "Origin," published in 1869, page 439.) yesterday in flower, and had to despatch it at once. I suppose some of your assistants will be able to make the genus out without great trouble. I have done little in experiment of late, but I find that mignonette is absolutely sterile with pollen from the same plant. Any one who saw stamen after stamen bending upwards and shedding pollen over the stigmas of the same flower would declare that the structure was an admirable contrivance for self-fertilisation. How utterly mysterious it is that there should be some difference in ovules and contents of pollen-grains (for the tubes penetrate own stigma) causing fertilisation when these are taken from any two distinct plants, and invariably leading to impotence when taken from the same plant! By Jove, even Pan. (221/4. Pangenesis.) won't explain this. It is a comfort to me to think that you will be surely haunted on your death-bed for not honouring the great god Pan. I am quite delighted at what you say about my book, and about Bentham; when writing it, I was much interested in some parts, but latterly I thought quite as poorly of it as even the "Athenaeum." It ought to be read abroad for the sake of the booksellers, for five editions have come or are coming out abroad! I am ashamed to say that I have read only the organic part of Lyell, and I admire all that I have read as much as you. It is a comfort to know that possibly when one is seventy years old one's brain may be good for work. It drives me mad, and I know it does you too, that one has no time for reading anything beyond what must be read: my room is encumbered with unread books. I agree about Wallace's wonderful cleverness, but he is not cautious enough in my opinion. I find I must (and I always distrust myself when I differ from him) separate rather widely from him all about birds' nests and protection; he is riding that hobby to death. I never read anything so miserable as Andrew Murray's criticism on Wallace in the last number of his Journal. (221/5. See "Journal of Travel and Natural History," Volume I., No. 3, page 137, London, 1868, for Andrew Murray's "Reply to Mr. Wallace's Theory of Birds' Nests," which appeared in the same volume, page 73. The "Journal" came to an end after the publication of one volume for 1867-8.) I believe this Journal will die, and I shall not cry: what a contrast with the old "Natural History Review."

LETTER 222. TO J.D. HOOKER. Freshwater, Isle of Wight, July 28th [1868].

I am glad to hear that you are going (222/1. In his Presidential Address at Norwich.) to touch on the statement that the belief in Natural Selection is passing away. I do not suppose that even the "Athenaeum" would pretend that the belief in the common descent of species is passing away, and this is the more important point. This now almost universal belief in the evolution (somehow) of species, I think may be fairly attributed in large part to the "Origin." It would be well for you to look at the short Introduction of Owen's "Anat. of Invertebrates," and see how fully he admits the descent of species.

Of the "Origin," four English editions, one or two American, two French, two German, one Dutch, one Italian, and several (as I was told) Russian editions. The translations of my book on "Variation under Domestication" are the results of the "Origin;" and of these two English, one American, one German, one French, one Italian, and one Russian have appeared, or will soon appear. Ernst Hackel wrote to me a week or two ago, that new discussions and reviews of the "Origin" are continually still coming out in Germany, where the interest on the subject certainly does not diminish. I have seen some of these discussions, and they are good ones. I apprehend that the interest on the subject has not died out in North America, from observing in Professor and Mrs. Agassiz's Book on Brazil how exceedingly anxious he is to destroy me. In regard to this country, every one can judge for himself, but you would not say interest was dying out if you were to look at the last number of the "Anthropological Review," in which I am incessantly sneered at. I think Lyell's "Principles" will produce a considerable effect. I hope I have given you the sort of information which you want. My head is rather unsteady, which makes my handwriting worse than usual.

If you argue about the non-acceptance of Natural Selection, it seems to me a very striking fact that the Newtonian theory of gravitation, which seems to every one now so certain and plain, was rejected by a man so extraordinarily able as Leibnitz. The truth will not penetrate a preoccupied mind.

Wallace (222/2. Wallace, "Westminster Review," July, 1867. The article begins: "There is no more convincing proof of the truth of a comprehensive theory, than its power of absorbing and finding a place for new facts, and its capability of interpreting phenomena, which had been previously looked upon as unaccountable anomalies..." Mr. Wallace illustrates his statement that "a false theory will never stand this test," by Edward Forbes' "polarity" speculations (see page 84 of the present volume) and Macleay's "Circular" and "Quinarian System" published in his "Horae Entomologicae," 1821, and developed by Swainson in the natural history volumes of "Lardner's Cabinet Cyclopaedia." Mr. Wallace says that a "considerable number of well-known naturalists either spoke approvingly of it, or advocated similar principles, and for a good many years it was decidedly in the ascendant...yet it quite died out in a few short years, its very existence is now a matter of history, and so rapid was its fall that...Swainson, perhaps, lived to be the last man who believed in it. Such is the course of a false theory. That of a true one is very different, as may be well seen by the progress of opinion on the subject of Natural Selection."

Here, (page 3) follows a passage on the overwhelming importance of Natural Selection, underlined with apparent approval in Mr. Darwin's copy of the review.), in the "Westminster Review," in an article on Protection has a good passage, contrasting the success of Natural Selection and its growth with the comprehension of new classes of facts (222/3. This rather obscure phrase may be rendered: "its power of growth by the absorption of new facts."), with false theories, such as the Quinarian Theory, and that of Polarity, by poor Forbes, both of which were promulgated with high advantages and the first temporarily accepted.

LETTER 223. TO G.H. LEWES.

(223/1. The following is printed from a draft letter inscribed by Mr. Darwin "Against organs having been formed by direct action of medium in distinct organisms. Chiefly luminous and electric organs and thorns." The draft is carelessly written, and all but illegible.)

August 7th, 1868.

If you mean that in distinct animals, parts or organs, such for instance as the luminous organs of insects or the electric organs of fishes, are wholly the result of the external and internal conditions to which the organs have been subjected, in so direct and inevitable a manner that they could be developed whether of use or not to their possessor, I cannot admit [your view]. I could almost as soon admit that the whole structure of, for instance, a woodpecker, had thus originated; and that there should be so close a relation between structure and external circumstances which cannot directly affect the structure seems to me to [be] inadmissible. Such organs as those above specified seem to me much too complex and generally too well co-ordinated with the whole organisation, for the admission that they result from conditions independently of Natural Selection. The impression which I have taken, studying nature, is strong, that in all cases, if we could collect all the forms which have ever lived, we should have a close gradation from some most simple beginning. If similar conditions sufficed, without the aid of Natural Selection, to give similar parts or organs, independently of blood relationship, I doubt much whether we should have that striking harmony between the affinities, embryological development, geographical distribution, and geological succession of all allied organisms. We should be much more puzzled than we now are how to class, in a natural method, many forms. It is puzzling enough to distinguish between resemblance due to descent and to adaptation; but (fortunately for naturalists), owing to the strong power of inheritance, and to excessively complex causes and laws of variability, when the same end or object has been gained, somewhat different parts have generally been modified, and modified in a different manner, so that the resemblances due to descent and adaptation can commonly be distinguished. I should just like to add, that we may understand each other, how I suppose the luminous organs of insects, for instance, to have been developed; but I depend on conjectures, for so few luminous insects exist that we have no means of judging, by the preservation to the present day of slightly modified forms, of the probable gradations through which the organs have passed. Moreover, we do not know of what use these organs are. We see that the tissues of many animals, [as] certain centipedes in England, are liable, under unknown conditions of food, temperature, etc., to become occasionally luminous; just like the [illegible]: such luminosity having been advantageous to certain insects, the tissues, I suppose, become specialised for this purpose in an intensified degree; in certain insects in one part, in other insects in other parts of the body. Hence I believe that if all extinct insect-forms could be collected, we should have gradations from the Elateridae, with their highly and constantly luminous thoraxes, and from the Lampyridae, with their highly luminous abdomens, to some ancient insects occasionally luminous like the centipede.

I do not know, but suppose that the microscopical structure of the luminous organs in the most different insects is nearly the same; and I should attribute to inheritance from a common progenitor, the similarity of the tissues, which under similar conditions, allowed them to vary in the same manner, and thus, through Natural Selection for the same general purpose, to arrive at the same result. Mutatis mutandis, I should apply the same doctrine to the electric organs of fishes; but here I have to make, in my own mind, the violent assumption that some ancient fish was slightly electrical without having any special organs for the purpose. It has been stated on evidence, not trustworthy, that certain reptiles are electrical. It is, moreover, possible that the so-called electric organs, whilst in a condition not highly developed, may have subserved some distinct function: at least, I think, Matteucci could detect no pure electricity in certain fishes provided with the proper organs. In one of your letters you alluded to nails, claws, hoofs, etc. From their perfect coadaptation with the whole rest of the organisation, I cannot admit that they would have been formed by the direct action of the conditions of life. H. Spencer's view that they were first developed from indurated skin, the result of pressure on the extremities, seems to me probable.

In regard to thorns and spines I suppose that stunted and [illegible] hardened processes were primarily left by the abortion of various appendages, but I must believe that their extreme sharpness and hardness is the result of fluctuating variability and "the survival of the fittest." The precise form, curvature and colour of the thorns I freely admit to be the result of the laws of growth of each particular plant, or of their conditions, internal and external. It would be an astounding fact if any varying plant suddenly produced, without the aid of reversion or selection, perfect thorns. That Natural Selection would tend to produce the most formidable thorns will be admitted by every one who has observed the distribution in South America and Africa (vide Livingstone) of thorn-bearing plants, for they always appear where the bushes grow isolated and are exposed to the attacks of mammals. Even in England it has been noticed that all spine-bearing and sting-bearing plants are palatable to quadrupeds, when the thorns are crushed. With respect to the Malayan climbing Palm, what I meant to express is that the admirable hooks were perhaps not first developed for climbing; but having been developed for protection were subsequently used, and perhaps further modified for climbing.

LETTER 224. TO J.D. HOOKER. Down, September 8th [1868].

About the "Pall Mall." (224/1. "Pall Mall Gazette," August 22nd, 1868. In an article headed "Dr. Hooker on Religion and Science," and referring to the British Association address, the writer objects to any supposed opposition between religion and science. "Religion," he says, "is your opinion upon one set of subjects, science your opinion upon another set of subjects." But he forgets that on one side we have opinions assumed to be revealed truths; and this is a condition which either results in the further opinion that those who bring forward irreconcilable facts are more or less wicked, or in a change of front on the religious side, by which theological opinion "shifts its ground to meet the requirements of every new fact that science establishes, and every old error that science exposes" (Dr. Hooker as quoted by the "Pall Mall"). If theologians had been in the habit of recognising that, in the words of the "Pall Mall" writer, "Science is a general name for human knowledge in its most definite and general shape, whatever may be the object of that knowledge," probably Sir Joseph Hooker's remarks would never have been made.) I do not agree that the article was at all right; it struck me as monstrous (and answered on the spot by the "Morning Advertiser") that religion did not attack science. When, however, I say not at all right, I am not sure whether it would not be wisest for scientific men quite to ignore the whole subject of religion. Goldwin Smith, who has been lunching here, coming with the Nortons (son of Professor Norton and friend of Asa Gray), who have taken for four months Keston Rectory, was strongly of opinion it was a mistake. Several persons have spoken strongly to me as very much admiring your address. For chance of you caring to see yourself in a French dress, I send a journal; also with a weak article by Agassiz on Geographical Distribution. Berkeley has sent me his address (224/2. The Rev. M.J. Berkeley was President of Section D at Norwich in 1868.), so I have had a fair excuse for writing to him. I differ from you: I could hardly bear to shake hands with the "Sugar of Lead" (224/3. "You know Mrs. Carlyle said that Owen's sweetness reminded her of sugar of lead." (Huxley to Tyndall, May 13th, 1887: Huxley's "Life," II., page 167.), which I never heard before: it is capital. I am so very glad you will come here with Asa Gray, as if I am bad he will not be dull. We shall ask the Nortons to come to dinner. On Saturday, Wallace (and probably Mrs. W.), J. Jenner Weir (a very good man), and Blyth, and I fear not Bates, are coming to stay the Sunday. The thought makes me rather nervous; but I shall enjoy it immensely if it does not kill me. How I wish it was possible for you to be here!

LETTER 225. TO M.J. BERKELEY. Down, September 7th, 1868.

I am very much obliged to you for having sent me your address (225/1. Address to Section D of the British Association. ("Brit. Assoc. Report," Norwich meeting, 1868, page 83.))...for I thus gain a fair excuse for troubling you with this note to thank you for your most kind and extremely honourable notice of my works.

When I tell you that ever since I was an undergraduate at Cambridge I have felt towards you the most unfeigned respect, from all that I continually heard from poor dear Henslow and others of your great knowledge and original researches, you will believe me when I say that I have rarely in my life been more gratified than by reading your address; though I feel that you speak much too strongly of what I have done. Your notice of pangenesis (225/3. "It would be unpardonable to finish these somewhat desultory remarks without adverting to one of the most interesting subjects of the day,—the Darwinian doctrine of pangenesis...Like everything which comes from the pen of a writer whom I have no hesitation, so far as my judgment goes, in considering as by far the greatest observer of our age, whatever may be thought of his theories when carried out to their extreme results, the subject demands a careful and impartial consideration." (Berkeley, page 86.)) has particularly pleased me, for it has been generally neglected or disliked by my friends; yet I fully expect that it will some day be more successful. I believe I quite agree with you in the manner in which the cast-off atoms or so-called gemmules probably act (225/4. "Assuming the general truth of the theory that molecules endowed with certain attributes are cast off by the component cells of such infinitesimal minuteness as to be capable of circulating with the fluids, and in the end to be present in the unimpregnated embryo-cell and spermatozoid...it seems to me far more probable that they should be capable under favourable circumstances of exercising an influence analogous to that which is exercised by the contents of the pollen-tube or spermatozoid on the embryo-sac or ovum, than that these particles should be themselves developed into cells" (Berkeley, page 87).): I have never supposed that they were developed into free cells, but that they penetrated other nascent cells and modified their subsequent development. This process I have actually compared with ordinary fertilisation. The cells thus modified, I suppose cast off in their turn modified gemmules, which again combine with other nascent cells, and so on. But I must not trouble you any further.

LETTER 226. TO AUGUST WEISMANN. Down, October 22nd, 1868.

I am very much obliged for your kind letter, and I have waited for a week before answering it in hopes of receiving the "kleine Schrift" (226/1. The "kleine Schrift" is "Ueber die Berechtigung der Darwin'schen Theorie," Leipzig, 1868. The "Anhang" is "Ueber den Einfluss der Wanderung und raumlichen Isolirung auf die Artbilding.") to which you allude; but I fear it is lost, which I am much surprised at, as I have seldom failed to receive anything sent by the post.

As I do not know the title, and cannot order a copy, I should be very much obliged if you can spare another.

I am delighted that you, with whose name I am familiar, should approve of my work. I entirely agree with what you say about each species varying according to its own peculiar laws; but at the same time it must, I think, be admitted that the variations of most species have in the lapse of ages been extremely diversified, for I do not see how it can be otherwise explained that so many forms have acquired analogous structures for the same general object, independently of descent. I am very glad to hear that you have been arguing against Nageli's law of perfectibility, which seems to me superfluous. Others hold similar views, but none of them define what this "perfection" is which cannot be gradually attained through Natural Selection. I thought M. Wagner's first pamphlet (226/2. Wagner's first essay, "Die Darwin'sche Theorie und das Migrationsgesetz," 1868, is a separately published pamphlet of 62 pages. In the preface the author states that it is a fuller version of a paper read before the Royal Academy of Science at Munich in March 1868. We are not able to say which of Wagner's writings is referred to as the second pamphlet; his second well-known essay, "Ueber den Einfluss der Geogr. Isolirung," etc., is of later date, viz., 1870.) (for I have not yet had time to read the second) very good and interesting; but I think that he greatly overrates the necessity for emigration and isolation. I doubt whether he has reflected on what must occur when his forms colonise a new country, unless they vary during the very first generation; nor does he attach, I think, sufficient weight to the cases of what I have called unconscious selection by man: in these cases races are modified by the preservation of the best and the destruction of the worst, without any isolation.

I sympathise with you most sincerely on the state of your eyesight: it is indeed the most fearful evil which can happen to any one who, like yourself, is earnestly attached to the pursuit of natural knowledge.

LETTER 227. TO F. MULLER. Down, March 18th [1869].

Since I wrote a few days ago and sent off three copies of your book, I have read the English translation (227/1. "Facts and Arguments for Darwin." See "Life and Letters," III., page 37.), and cannot deny myself the pleasure of once again expressing to you my warm admiration. I might, but will not, repeat my thanks for the very honourable manner in which you often mention my name; but I can truly say that I look at the publication of your essay as one of the greatest honours ever conferred on me. Nothing can be more profound and striking than your observations on development and classification. I am very glad that you have added your justification in regard to the metamorphoses of insects; for your conclusion now seems in the highest degree probable. (227/2. See "Facts and Arguments for Darwin," page 119 (note), where F. Muller gives his reasons for the belief that the "complete metamorphosis" of insects was not a character of the form from which insects have sprung: his argument largely depends on considerations drawn from the study of the neuroptera.) I have re-read many parts, especially that on cirripedes, with the liveliest interest. I had almost forgotten your discussion on the retrograde development of the Rhizocephala. What an admirable illustration it affords of my whole doctrine! A man must indeed be a bigot in favour of separate acts of creation if he is not staggered after reading your essay; but I fear that it is too deep for English readers, except for a select few.