Geanies, Ross-shire, N.B.: October 21. 1889.

My dear Poulton,—Many thanks for your interesting letter. From it I quite understand your views about the relation between reproduction and repair; are they those of Weismann or altogether your own? And have they, as yet, been published anywhere? If not, I suppose it is undesirable to allude to them in public? The theory is ingenious, but seems to sail rather near Pangenesis (as do many of the latter amendments of germ-plasm by W.); and I should have thought that the limbs of salamanders, &c., are too late products, both phylogenetically and ontogenetically, to fall within its terms.

I also see better what you mean about Sphex. But Darwin's letter in 'Mental Evolution in Animals' seems to me to meet (or rather to anticipate) the 'difficulty.' Of course, he did not suppose that the insects' knowledge of 'success' goes further than finding out and observing the best place to sting in order to produce the maximum effect. The analogy of Cymphs is apposite; but is it the fact that there is any species whose localisation is really comparable with that of Sphex? Contrasting Weismann's account with Fabre's, I should say not.

As for neuter insects (which you mentioned at Newcastle), Darwin allows that they constitute one of the most difficult cases to bring under natural selection, seeing that this has here to act at the end of a long lever of the wrong kind, so to speak. Read Perrier's preface to French translation of 'Mental Evolution in Animals,' and observe how good his suggestion is, on the supposition that Lamarckian principles have any applicability at all.

Lastly, at Newcastle you said something that seemed to imply a doubt upon such facts as Lord Morton's mare. Do you really doubt such facts? I cannot suppose it.

There are plenty of white stoats hereabouts, I believe, though I have never actually seen them, because I do not stay late enough in the year. I have told my keeper to try to catch some without injuring them, and, if he succeeds, to send them straight to the Zoo. The experiment would be a very interesting one. But the keeper says that even here the whiteness depends as to its intensity upon the amount of snow in different seasons. He is most positive about this; he says it depends upon snow, and not on cold. However, I do not quote him as an authority in science, although he certainly is an intelligent and observing man.

Regarding the Royal Institution, an after Easter course by you would be doubly interesting, because before Easter I have to give one on the 'Post-Darwinian Period,' which will be mainly concerned with Weismann. Your lectures might then serve as a counter-irritant, therefore I will do anything I can to bring them about, only, not being on the managing body, I can help merely by backing any application you may make. And, of course, there ought to be no difficulty about it. Only let me know if you should want backing.

Would it not be worth while to get also some mountain hares for observation at the Zoo? These, I think, I could get.

Yours very truly,

Geo. J. Romanes.

Geanies, Ross-shire, N.B.: October 15.

Would you mind sending me the part of your MS. dealing with Sphex? I do not know that I quite caught your objection to my difficulty, and want to allude to it in lectures which I am now preparing for my Edinburgh class.

Also, did I correctly understand you to say that you refused to acknowledge any fundamental identity between processes of reproduction and those of repair? For this identity is to my mind the most important of all objections to W.'s theory.

G. J. Romanes.

18 Cornwall Terrace, Regent's Park, N.W.: December 3, 1889.

My dear Poulton,—I returned here a day or two ago, and now send you my copy of Perrier's remarks about the neuters of hymenopterous insects. But he said a good deal more in subsequent and private correspondence. His preface, however, will serve to show you the general tone of argument.

With regard to Panmixia, it occurs to me that very likely you have not seen all that I wrote upon it, as the three papers were scattered over several months in 'Nature.' The following are the references: Vol. ix. pp. 361, 440; vol. x. p. 164.

You will see that I took up a decided stand upon the principle of Panmixia not being able altogether to supersede that of disuse. This was for the reasons stated in my last letter; and I still see no further reason for changing the opinion that was then formed under the influence of Darwin's judgment.

With reference to the difference that you alluded to—and which, as far as I can see, is the only difference between Weismann's presentation of the principle and my own—I enclose an extract from the lecture which I have just been giving in Edinburgh. From this extract I think you will see that the one point of difference does not redound to the credit of Weismann's logic. After reading the extract in conjunction with the papers in 'Nature,' perhaps you will let me know whether you now understand my view any better, or still believe that the cessation of selection alone can reduce the average of a useless organ below fifty per cent, of its original size—so long, that is, as the force of heredity continues unimpaired.

G. J. Romanes.

To Professor Thiselton-Dyer.

December 20, 1888.

Dear Dyer,—Would you mind sending me on a postcard the name of the genus of plants the constituent species of which you alluded to in the train as being mutually fertile, and also separated from one another topographically? I want to get as many of such cases as I possibly can, so, if any others occur to you, please mention them likewise.

By reading pages 401 and 404 of my paper, you will see why such cases are of quite as much importance to me as the converse, viz. where closely allied species inhabiting continuous areas are more or less mutually sterile (see p. 392).

If you have hitherto failed to apply these converse tests to my theory, I cannot conceive by what other principle you have sought to test it. Pray read the passages referred to, which present the shortest summary of what I regard as the very backbone of my evidence.

If your large knowledge of geographical distribution should enable you to supply me with specific cases of the general principle mentioned by Darwin in the quotation given on page 392 ('Origin of Species,' 6th ed., pp. 134-5), I should much like to try experiments on the sterility which I should expect to find between these interlocking species.

It seems comical to ask a scientific opponent for assistance, but the fact of being able to do so proves the superiority of science to politics.

December 25, 1888.

It is very good of you to write such a long and suggestive letter.

As a result of attentively reading your letter, it appears to me that you think I suppose sterility in a high degree to be much more usual among allied species than I do suppose it. I well know the large amount of natural as well as artificial hybridisation that goes on. But, on the other hand, there are so many species which either will not cross at all, or produce sterile hybrids, that, taking a general view of all species together, mutual sterility does become by far the most generally distributed single peculiarity—i.e. is the one peculiarity which, more than any other that can be named, is common to numberless species.

Thus much for mutual sterility that is absolute, either in first crosses or in their hybrid progeny. But now, the most important thing for me is mutual sterility that is not absolute (though, on my theory, perhaps on its way to becoming so) but relative, i.e. there being a lower degree of fertility between A × B or B × A, than there is between A × A or B × B.

Hitherto very few experiments have been made on these comparative degrees of fertility, yet it is by such alone, it seems to me, that physiological selections can be tested. Thus, e.g., my point about the 'interlocking' species (p. 392) is that in such cases I should expect a higher degree of fertility in A × A and B × B than crosswise. Indeed, my fear is that when I shall have proved by experiment that such is the general rule in such cases, naturalists will turn round and say: 'Well, of course, on merely a priori grounds you might have known that such must have been the case; for otherwise the two interlocking species could never have existed as separate species, they would have hybridised freely along the whole frontier line and eventually blended over the whole area.' And still more may this be said in the case of allied species, not merely interlocking, but intermixed through common areas. Therefore, as a believing F.R.S. said to me the other day, 'Your letters in "Nature" will at least have the effect of blunting the edge of such possible criticism in the future.' Of course you will laugh at the robustness of my faith in thus forecasting the line of future opposition, but I would like to ask you this much: Supposing, for the sake of argument, that twenty years hence I publish one hundred instances of allied species which grow intermixed in common areas, proving by experiment that in all the cases there is some comparative degree of sterility between them (if only due to pre-potency of their own pollen), would you regard this as making in favour of physiological selection? Or are you already prepared to admit that such must be the case, since otherwise the species A and B could not exist without fusion into one? If you say that you are prepared to admit this, it seems to me that you have already accepted the theory of physiological selection on a priori grounds.

Again, if I should publish one hundred other instances of allied species topographically isolated from one another, all of which were proved by experiment to present no degree at all of mutual infertility (so that A × A and B × B are not more fertile than crosswise), would you allow that, taken in conjunction with the previous set of experiments, these finally prove the theory of physiological selection to be true? If not, I do not see how it is possible to verify the theory at all: it is only by means of these two complementary lines of research that, as it seems to me, the theory can be experimentally tested.

In the former case—i.e. where allied species intermix in common areas—sometimes they intercross freely (e.g. Primula vulgaris and veris, Geum urbanum and rivale, Rumex, Epilobium, &c.), while in other instances they don't (e.g. Ranunculus repens and bulbosus, Lepidium Smithii and campestre, Scrophularia nodosa and aquatica, &c.). Now, as regards the latter, I suppose you would not question that the 'physiological isolation' has to do with preventing the species from fusing? But, if so, by parity of reasoning, should we not expect to meet with some degree of the same thing in the other cases, which, although not here sufficiently pronounced to block off frequent hybridisation, is nevertheless sufficient to prevent the species from blending over their common area?

And here, I may say, I should not at all object to the charge of misunderstanding Darwin on any merely trivial point such as the one you mention. But in this instance it so happens that it is rather you who have misunderstood me. I know that 'a hybrid is not an intermediate form in his sense,' and this is just what constitutes my difficulty against his paragraphs quoted on p. 392 of my paper. For what I say is, these intermediate forms ought to be hybrids, unless physiological selection, (i.e. mutual sterility) has been at work. 'In his sense' I cannot conceive how such 'intermediate forms' can exist in the circumstances described, seeing that they are not hybrids, and yet that (in the absence of any hypothesis of physiological isolation for which I am contending) there is no reason given why the two interlocking species should not freely intercross.

Regarding sexual selection I certainly am very much in earnest about its parallel to p.s.[62] If you intend the meaning of n.s. so as to embrace s.s. it will at the same time embrace also p.s. For s.s., like p.s., has nothing to do with life-preserving characters; yet, also like p.s., it has to do with the differentiation of specific forms. (There is no distinction to be drawn between 'the species of a cock' and 'the plumage of a cock': plumage is the most favourite part of a bird with ornithologists on which to found specific diagnoses.) Therefore, if p.s. is true at all—which, of course, is another question—even my celebrated powers of 'dialectical subtlety' are completely unable to perceive any difference between p.s. and s.s. in respect of their relation to n.s.

Lastly, as regards Nägeli, no doubt he is an out-and-out Lamarckian, but I did not see that this should make any difference touching his opinion on a matter of fact not more connected with Lism. than Dism. I will look up 'Nature' for 1870.

With best Christmas wishes and many thanks for botanical hints.

December 26, 1888.

It has occurred to me that if you know Churchill's address, I might save time by writing to him before seeing him when he comes in spring.

It has also occurred to me that I might perhaps put the argument on pp. 801-4 better before you thus:

If phys. sel. is true, it would follow that as between allied species, mutual sterility ought to occur in all degrees (from zero to absolute), and that there ought to be a correlation between these degrees of sterility and degrees of non-separation, topographically.

Now, you cannot possibly doubt that the first expectation is realised in nature; as between allied species sterility does occur in all degrees, from there being no such sterility at all in very many cases, to there being absolute sterility in other cases. Therefore, in stating this fact as a fact, I am not playing at 'heads I win and tails you lose,' nor 'begging the whole question at the outset.' Any 'question' really arises only with regard to the second expectation—viz. whether there is a general correlation between degrees of mutual fertility and degrees of topographical isolation.

Now, this question I have not begged, but, on the contrary, stated as the question by an experimental answer to which my theory must stand or fall.

Thus, the cases which you mention obviously go to support the theory, inasmuch as they conform to the expectation above mentioned. What I want to do is to find as many genera as possible like binchona and begonia, where the constituent species are separated geographically or topographically, and (? in consequence) easily hybridise with one another.

Therefore, as a mere matter of method, I cannot see that I have begged any question: for the only question is not about the facts which I state, but about my suggested explanation of them. And this question can only be answered by ascertaining whether there is in nature any such general correlation between isolation and capability of hybridising (also, of course, between the absence of isolation and the absence of such capability) as my theory would require.

Yours very sincerely,

G. J. Romanes.

18 Cornwall Terrace, Regent's Park, N.W.: December 27, 1888.

I am most glad that in your last letter you deal with what I consider the real 'question'—viz. not whether degrees of sterility obtain among a large proportional number of species, but whether there is any such correlation between them and absence of isolation of other kinds as my theory would expect. And, in dealing with this question you hit upon precisely the two greatest difficulties which I have myself concluded lie against the theory. The first is about areas now discontinuous having been once continuous, and our being so often unable to say whether or not such has been the case. But this difficulty is one that lies against verification of the theory, not against the theory itself. It was in view of this difficulty that I mentioned oceanic islands as furnishing the best flora for trying experiments upon; but since I published the paper, I have not been able to hear of any botanists visiting islands. Should you ever hear of any you might let me know.

The second difficulty is one that lies against the theory itself, and has always seemed to me most formidable. But as nobody else has ever mentioned it, I have not hitherto done so, as I want to work it out quietly. I allude to your remark about the extraordinary differences that obtain among different genera with regard to the capability of intercrossing exhibited by their constituent species. This, I confess, has from the first appeared a tremendous objection to my theory. On the other hand, I have taken comfort from the consideration that besides being a tremendous objection, it is also a tremendous mystery. For, as it must admit of some explanation, and as this explanation must almost certainly have to do with the sexual system, it becomes not improbable that when found the explanation may square with p.s. That the difference in question is functional and not structural (or physiological as distinguished from morphological) seems to be proved by the fact that in some cases it obtains as between the most closely allied genera, being, e.g., most strongly pronounced of all between Geranium and Pelargonium. Even quite apart from my own theory, it seems to me that this is a subject of the highest importance to investigate.

As regards sexual selection I allow, of course, that the 'law of battle' is a form of natural selection. But where the matter is merely a pleasing of æsthetic taste, and the resulting structures therefore only ornamental, I can see nothing 'advantageous' in the sense of life-preserving. On the contrary, in most cases such structures entail considerable expenditure of physiological energy in their production. On this account Darwin says that nat. sel. must impose a check on sexual selection running beyond a certain point of injuriousness ('D. of M.,' p. 227). Now, physiological selection is never thus injurious; and although it is a 'form of isolation,' the isolation is neither so extreme nor of such long continuance as the ones you compare it with. Moreover, the environment (therefore all other or external conditions of life) remain the same, which is not the case under the other forms of isolation. Provided that the physiological change is not in itself injurious, I do not see why physiologically isolated forms should be less fit than those from which they have been separated, though I can very well see why this should be the case with such geographically isolated forms as you mention, for there the schooling is different. Lastly, physiological selection, if not in itself injurious, does not require that its children should be 'protected against the struggle for existence.' On the contrary, as I say in my paper, it is calculated to give this struggle a better chance than ever to develope adaptive character in the sexually isolated forms, because the swamping effects of intercrossing are diminished.

But I really did not intend to afflict you with another jaw of this kind. I am, however, very glad that we now understand each other better than we did. At all events on my side I think I now know exactly the points which I have to make good if Nature is so constituted as to admit of my theory. One thing only I have forgotten to say, viz. that nothing can be argued against the theory from the fact of hybridisation occurring in cases where, according to the theory, it ought not to occur. This argument only becomes valid where it is found that the resulting hybrids are fertile. In relation to the theory, a sterile hybrid is all the same as a failure to cross.

Yours very sincerely,

G. J. Romanes.

P.S.—I forgot to ask you if there would be any facilities in spring at Kew for repeating Adam's graft of purple on yellow laburnum. I want to try this experiment in budding on a large scale because of its importance on Weismannism, should the result of any of the grafts go to corroborate Adam's account of the way in which he produced the hybrid. If you agree to the experiments being tried at Kew, perhaps you might let me know whether there are any purple laburnums already in the gardens, or whether I should get the material over from France. But in that case you might also let me know to whom in France or elsewhere I had best apply. However, do not bother to answer any other parts of this tremendous letter, these we can discuss in conversation hereafter. A postcard to answer this postscript, however, is desirable, as then it might be possible to get matters in train for next budding season.

G. J. R.

I should much like to meet Churchill. Will you remember to tell me when he comes?

To F. Darwin, Esq.

18 Cornwall Terrace, Regent's Park, N.W.: January 20, 1889.

Dear Darwin,—Many thanks for your long letter. I thought you might have had some notes or memories of conversations, to show in a general way what the 'line' would have been.[63] If so, of course I should not have said that my sayings were inspired, but should myself have known that I was not going astray.

The line I am going to take is:

1st. Even assuming, for sake of argument, that heightened colour is correlated with increased vigour, Wallace everywhere fails to distinguish between brilliancy and ornament; yet it is the disposition of colours in patterns, &c., that is the chief thing to be explained.

2nd. In many cases (e.g. peacock's tail) the pattern is only revealed when unfolded during courtship. Besides natural selection could not be such a fool as to develope large (physiologically expressive) and weighty (impeding flight) structures like this—stags' antlers, &c., merely as correlates of vigour.

3rd. There is not much in Wallace's merely negative difficulty about our not knowing what goes on in the mind of a hen, when we set against that difficulty the positive fact that we can see what does go on in the mind of a cock—display, antics, song, &c.

4th. To say that 'each bird finds a mate under any circumstances' is merely to beg the whole question.

5th. There remains Wallace's jealousy of natural selection. He will not have any other 'factor,' and therefore says natural selection must eat up sexual selection like the lean kine have the fat kine. But natural selection alone does not explain all the phenomena of sexual colouring, courtship, &c., and sexual selection is exactly the theory that does. Wallace's jealousy, therefore, is foolish and inimical to natural selection theory itself, by forcing it into explanations which are plainly false.

My own belief is, that what Lankester calls the 'pure Darwinians' are doing the same thing in another direction. By endeavouring, with Wallace and Weismann, to make natural selection all in all as the sole cause of adaptive structure, and expressly discarding the Darwinian recognition of use and disuse. I think they are doing harm to natural selection theory itself. Moreover, because I do not see any sufficient reason as yet to budge from the real Darwinian standpoint (Weismann has added nothing to the facts which were known to Charles Darwin), the post-Darwinians accuse me of moving away from Darwinian principles. But it is they who are moving, and, because they see a change in our relative positions, affirm that it is I. In point of fact, my position has never varied in the least, and my confession of faith would still follow, in every detail, that given on p. 421 of 'Origin,' 6th ed., which, it seems to me, might also be regarded as prophetic no less than retrospective.

If I did not say all this in my paper in physiological selection, it is only because I never conceived the possibility of my being accused of trying to undermine natural selection; and, therefore, I only stated as briefly as possible what my relations were to it. Yet it seems to me that this statement was clear enough if Wallace had not come down with his preposterous 'Romanes versus Darwin.' At all events, it is not in my power—or, I believe, in that of anybody else—to express more strongly than I now have in 'Nature,' in answer to Dyer, what I do hold about natural selection in its relation to physiological selection, sexual selection, and other subordinate principles. Of course, if there were a debate on these lines at the B.A., I should get my part of it published somewhere. As far as I can honestly see, my 'position' is absolutely identical with that in last editions of 'Origin' and 'Descent,' with, perhaps, a 'tendency' to lay more stress on levelling influence of Panmixia.

Re physiological selection. I have sent Correvon, of Geneva, £50 to help in founding a garden in the Alps, which will have the proud distinction of being the highest garden in the world. He is a splendid man for his knowledge of Alpine flora, and besides, is strongly bitten with a desire to test physiological selection. Of course I shall do the hybridising experiments myself, but he will collect the material from the different mountains—i.e. nearly allied species, topographically separated, and therefore, I hope, mutually fertile. The converse experiments of nearly allied species on common areas may be tried in England.

I am making arrangements for repeating on an extensive scale experiments on budding purple laburnum on yellow, to see if it is possible to reproduce 'Adam's eye' hybrid. If so, it would now be of more importance than ever in relation to Weismann. By the way, he is sorely put to it in the case of plants which reproduce themselves not only by cuttings, but even by leaves. Here he is bound to confess that his germ-plasma occupies all the cellular tissue of the entire plant. But if so, how in the world does his germ-plasma differ from gemmules?

There! I did not intend to write you anything of a letter when I began, but have gone on and on till it is well for you that the second sheet is coming to an end.

Yours ever,

G. J. Romanes.

P.S.—Any contributions to Correvon's garden (however small) would be thankfully received by him. Possibly his garden may be of some use to English botanists; if so, you might send the hat round, and collect any coppers that fall.

To Professor Thiselton-Dyer.

18 Cornwall Terrace, Regent's Park, N.W.: January 7, 1889.

My dear Dyer,—Knowing what a busy man you are, I never expected you to answer my last letter, and therefore it has come as an agreeable surprise. For no doubt you will believe me when I say that I value much more communications which are opposed to physiological selection than those in its favour; the former show me better what has to be done in the way of verification, as well as the general views which may be taken on the subject by other minds. And most of all is this the case when anyone like yourself gives me the benefit of opinions which are formed by a trained experience in botany, seeing that here I am myself such a sorry ignoramus. And I willingly confess that your strongly expressed opinion has seriously shaken my hopes for physiological selection, notwithstanding that some German botanists think otherwise. Nevertheless, I still think that it is worth while to devote some years to experimental testing, and then, if the results are against me—well, I shall be sorry to have spent so much time over a wild flower chase, and to have kicked up so much scientific dust in the process; but I will not be ashamed to acknowledge that Nature has said No.

And now for your last letter. Read in the light of subsequent experience, I have no doubt that I ought to have expressed myself with more care while writing my paper. But, to tell the honest truth, it never once occurred to me that I of all men could be suspected of trying to undermine the theories of Darwin. I was entirely filled with the one idea of presenting what seemed to me 'a supplementary hypothesis,' which, while 'in no way opposed to natural selection,' would 'release the latter from the only difficulties' which to my mind it had ever presented. Therefore I took it for granted that everybody would go with me in recognising natural selection as the 'boss' round which every 'other theory' must revolve, without my having to say so on every page. So, of course, by 'other theory' I did not mean that physiological selection was in my opinion the only theory of the origin of species. Everywhere throughout the paper, from the title-page to the conclusion, I represented it as an 'additional suggestion,' a 'supplementary hypothesis,' &c., &c. Sexual selection is in my view (as it is also in Darwin's, Wallace's, and doubtless that of all evolutionists) one of the 'other theories that have been propounded on the origin of species.' So is Lamarck's theory, which was considered by Darwin as more or less 'supplementary' to natural selection; and this is all that I meant—or, I should say, could possibly be understood to mean in view of the title-page, &c.—by speaking of physiological selection as another theory of the origin of species. It certainly is not the same thing as natural selection or either of the 'other theories' just mentioned; but no less certainly it is not exclusive of any of the three. Unquestionably it is as you say, and as I myself said, an independent theory—i.e. not identical with, but additional to, that of natural selection. But this is a widely different thing from saying that it is in itself an exhaustive theory, which must therefore swallow up all or any 'others.' In short, I abide by the closing statement of my introductory paragraph—viz. that the theory is an 'attempt at suggesting another factor in the formation of species, which, although quite independent of natural selection, is in no way opposed to natural selection, and may therefore be regarded as a factor supplementary to natural selection.' Statements to the same effect are indeed scattered through the entire paper; but, of course, could I have foreseen the interpretations which afterwards arose, I should have reiterated such statements ad nauseam.

Sorry you cannot come to the B.A., or to dine, but certainly do not wonder.

Yours very sincerely,

G. J. Romanes.

Lastly, about species not being able to exist as species without the physiological isolation of physiological selection (p. 403), the statement of course only applies to nearly allied species occupying common areas (see p. 404). If this statement is wrong, no one has yet shown me wherein it is so. I fancy you do not quite appreciate that by 'sterility' I always mean (unless otherwise expressly stated) sterility in some degree, and this not only with regard to the fertile hybrids. It is by no means enough to point to natural and fertile hybrids as cases opposed to physiological selection unless it has been shown by experiment through a generation or two that these hybrids are fully fertile—i.e. as fertile as their parent species. Now, experiments of this kind have rarely been carried through. If you assume that the result of carrying them through would be destructive of physiological selection by proving that fertile hybrids are, as a rule, fully fertile, and also (which is very important) that in any cases where experiment may show them to be so, further experiment would fail to show that isolation has not been effected in any other way (as by pre-potency, differences of insect fertilisation, &c.)—in short, if you assume that fertility is as complete between the two associated species as it is within each species, how is it conceivable that they should continue to be distinct? In this connection it is well to consult Gulick's paper already referred to (especially p. 259, paragraph 1st) on the theoretical side, and Jordan's papers and books on the practical side. I have repeated the latter's observations on poppies, and find that where any considerable number of individuals are concerned, natural selection is not nearly so great a power in this respect. (Even in cases where it happens that in-breeding is necessarily confined to single hermaphrodite individuals for numberless generations, the handicapping is not fatal: witness flowers which habitually fertilise themselves before opening—especially some species of orchids, which never seem to do otherwise, notwithstanding the elaborate provisions for cross-fertilisation in other species.) Now, I believe most of all in what I have called 'collective variation' of the reproductive system in the way of physiological selection, whereby, owing to some common influence acting on a large number of individuals similarly and simultaneously, they all become sexually co-adapted inter se while physiologically isolated from the rest. This essential feature of the theory seems to me entirely to remove the difficulty about in-breeding, as well as that which Wallace urged about the chances against a suitable meeting of 'physiological complements.'

As for my having attributed too much to the swamping effects of intercrossing (Panmixia), this, I am convinced, is the one and only particular wherein I have at all departed from the judgments of Darwin; though, curiously enough, it is the particular on which my critics have laid least stress when accusing me of Darwinian heresy. But it is too big a question to treat in correspondence. Gulick's recently published paper at the Linnean Society seems to me a most important one in this connection, and I have a large body of other evidence.

To F. Darwin, Esq.[64]

18 Cornwall Terrace, Regent's Park, N.W., January 8, 1889.

Dear Darwin,—Hate you, indeed! Why, I cannot imagine any better service than that of stopping a fellow from making a fool of himself, and I most cordially thank you for having done so in this case. The business was so completely out of my line, that I did not know what was required. It seemed to me that if I got any evidence of bending towards the sparks, the only question I wanted to answer would be answered, and, therefore, that it did not matter a straw about temperature, moisture, and the rest. Moreover, the results did not seem to me to be of any importance, as they were just what might have been expected, and, therefore, I doubted whether it was worth while publishing a paper about them. Had they gone, the other way, and proved that the plants would not bend to flashing light, I should have thought it much more interesting. Lastly, the research was so expensive, costing £1 per day at the only place where I could get the requisite apparatus, and there they shut up at night.

Of course, I will withdraw this paper, and, if you think the thing is worth working out in all the details you suggest, will do so. In that case, it would be worth while to ascertain whether there would be any electrical apparatus at Cambridge which I could get the use of at a lower rate of profit to the owners. A good-sized induction coil is really all that is required, and they probably have this in the Cavendish. But there is not one available in any of the London workshops, and so I had to go to Appes, in the Strand. It is suggested that the debate in Section D at the British Association this year should be opened by me on the question of utility as universal. Before I agree, I should like to know what you think about the 'Nature' controversy which I have recently had with Dyer, and out of which the present suggestion has emanated. Perhaps we might arrange to meet somewhere soon to have a talk over the expediency of such a debate at all, and the lines on which, if held, it should run. Of course, physiological selection would be carefully kept out. My object would be to show the prime importance of natural selection as a theory which everywhere accounts for adaptations.

Yours very sincerely,

G. J. Romanes.

May 27, 1889.

Herewith I return, with many thanks, a pamphlet by Kerner, numbered 738.

In my experiments with electric spark illumination on plants, I notice that the seedlings, although so wonderfully heliotropic, never form chlorophyll, even if exposed to a continuous stream of sparks for 30 hours on end, while they will bend through 90° in seven hours to single sparks following one another at one per second. This proves that there is no connection at all between heliotropism and formation of chlorophyll, or vice versa—a point which I cannot find to have been hitherto stated. Do you happen to know if it has been? If you do not happen to remember anything bearing on this subject, do not trouble to search or to answer.

Wallace's book[65] strikes me as very able in many parts, though singularly feeble in others—especially the last chapter. He has done but scant justice to Gulick's paper. Had he read it with any care, he might have seen that it fully anticipates his criticism on mine. But I think he deserves great credit for nowhere chuckling. From the first he has been consistent in holding natural selection the sole factor of organic evolution—leaving no room for sexual selection, inheritance of acquired characters, &c., &c. And now that he had lived to see an important body of evolutionists adopting this view, there must have been a strong temptation to 'I always told you so.' Yet there is nowhere any note of this, or even so much as an allusion to his previous utterances on the subject.

To E. B. Poulton, Esq.

Geanies, Ross-shire: November 2, 1889.

My dear Poulton,—Continuing our antipodal correspondence, and taking the points in your last letter seriatim, I quite saw that your theory of repair was 'the logical outcome of Weismann's' (being, in fact, a direct application of his views on phylogeny to the case of repair); but I did not know whether the outcome had been traced by him or by yourself. Now, I understand, I may allude to it as yours. Again, what I meant about regeneration of entire limbs, &c., was that, to meet such cases, your diagram would require modification in the way that you now suggest. Has it occurred to you as an argument in favour of this suggestion (i.e. that the 'potentiality' of somatic germ-plasm may in such cases be arrested in its process of ontogenetic diffusion), that Darwin has shown, or at least alleged, that all such cases may be traced to special adaptation to special needs, dangers, &c.—so that the arrest may have been brought about in these cases by natural selection?

If you deem the 'chief difference' between Darwin's and Weismann's theory of heredity to be 'that the one implies material particles and the other only physical and chemical constitution,' then, it seems to me, Weismann's theory will become identical with Herbert Spencer's—seeing that this is virtually the only respect in which Spencer's differs from Darwin's. But I think there is another and a much more important respect in which W.'s theory differs from both these predecessors. However, to proceed to the next point, I agree with you, that the sole object of the Sphex stinging the larvæ is now to cause them to 'keep,' and that natural selection must have worked upon this for perfecting the instinct. But the point is, what was the origin of the selective stinging? If merely chance congenital variations, would unity to billions express the chances against their ever arising? Get some mathematician to calculate—giving as data superficial area of caterpillar on the one hand and that of nine ganglia on the other. Even neglecting the consideration that the variation must occur many times to give unaided natural selection a chance to fix it as an instinct, the chances against its occurring only once would be represented by the following series, where x is the superficial area of the caterpillar minus that of eight ganglia, and unity is superficial area of one ganglia:

¹/_x × ¹/_x × ¹/_x × ¹/_x × ¹/_x × ¹/_x × ¹/_x × ¹/_x × ¹/_x

If, as I suppose, x may here be taken as = 100,000, the chances against the variation occurring once would be written in figures expressing unity to one thousand million billion trillions. Of course I do not rely on calculations of this kind for giving anything like accurate results (mathematics in biology always seems to me like a scalpel in a carpenter's shop), but it makes no difference how far one cuts down such figures as these. Therefore, if Lamarck won't satisfy such facts, neither do I think that Darwin minus Lamarck can do so. We must wait for the next man.

I will send you 'Perrier' on my return to town next month.

Lord Morton's experience is so universally that of all breeders of live stock, that I never knew anybody ever doubted it. But, if they do, there is no reason why they should not satisfy themselves on the point. For my part I do not feel that the fact requires any corroboration as regards mammals, though I have some experiments going on with birds. Lastly, the apparently analogous cases in plants are still worse for Weismann's theory, and they stand on the best authorities.

I enclose a letter received by same post that brought yours. It is from a former keeper of mine who is now more in the moorlands. Other applications are out, so I hope some of them will be successful. Very little doubt it will prove to be temperature. I found a dead stoat here to-day; it had not turned white at all, but then the season is very mild.

The Secretary of the R.I. is Sir F. Bramwell, Bart., F.R.S. You had better write to him. Also to his son-in-law, Victor Horsley, who is more of a biologist. Tell Bramwell, if you like, that I think he ought to jump at you.

Yours very truly,

G. J. Romanes.

Geanies, Ross-shire, N.B.: November 6, 1889.

My dear Poulton,—Many thanks for your paper, which is the clearest exposition I have yet seen of Weismann's views. But how about your allusion to experiments in grafting? As regards plants, there is a good deal of evidence as to the possibility of a graft-hybrid. As regards animals, fifteen years ago I spent an immensity of time in experimenting, and could not then find that there was any literature on the subject. Nobody who had grafted animal tissues had done so with any reference to the heredity question, nor do I know of any publications on the subject since then.

Yours very truly,

G. J. Romanes.

Geanies, Ross-shire, N.B.: November 11, 1889.

My dear Poulton,—Although I spent more time and trouble than I like to acknowledge (even to myself) in trying to prove Pangenesis between '73 and '80, I never obtained any positive results, and did not care to publish negative. Therefore there are no papers of mine on the subject, although I may fairly believe that no other human being has tried so many experiments upon it. No doubt you will think that I ought to regard this fact as so much negative evidence in favour of the new theory; and, up to a certain point, I do, only the issue between Pangenesis and Germ-plasm is not really or nearly so well defined as Weismann represents, where the matter of experiments is concerned; e.g. it is not the case that any crucial test is furnished by the non-transmissibility of mutilations; Darwin did not set much store by them, though Eimer and others have done so since. In fact all the Germans on both sides, and all the Englishmen on Weismann's side, seem to me unjust to Darwin in this respect.

Regarding the cessation of selection, the motive that prompted my question to you was not the paltry one of claiming priority in the enunciation of an exceedingly obvious idea. My motive was to assure myself that this idea is exactly the same as Weismann's Panmixia; for, although I could see no difference, I thought perhaps he and you did (from absence of allusion to my paper, while priority is acknowledged as regards a later one); and, if this were so, I wanted to know where the difference lay. And the reason I wanted to know this was because when my paper was published, and Darwin accepted the idea with enthusiasm, I put it to him in conversation whether this idea might not supersede Lamarckian principles altogether. (By carefully reading between the lines of the paper itself, you will see how much this question was occupying my mind at the time, though I did not dare to challenge Lamarck's principles in toto without much more full inquiry.) Then it was that Darwin dissuaded me from going on to this point, on the ground that there was abundant evidence of Lamarck's principles apart from use and disuse of structures—e.g. instincts—and also on the ground of his theory of Pangenesis. Therefore I abandoned the matter, and still retain what may thus be now a prejudice against exactly the same line of thought as Darwin talked me out of in 1873. Weismann, of course, has greatly elaborated this line of thought; but what may be called the scientific axis of it (viz. possible non-inheritance of acquired characters) is identical, and all the more metaphysical part of it about the immortality, immutability, &c., of a hypothetical germ-plasm is the weakest part in my estimation.

Now, the point I am working up to is this. If there be no difference between Panmixia and Cessation of Selection, from what I have briefly sketched about it, it follows that, had Darwin lived till now, he would almost certainly have been opposed to Weismann. This is not a thing I should like to say in public, but one that I should like to feel practically assured about in my own mind.

Regarding the numerical calculations, I have not got a copy of the 'Nature' paper here, but, so far as I remember (and I think I am right), the idea was that 'Economy of Growth' would go on assisting Cessation of Selection till the degenerating organ became 'rudimentary.' In other words, reversal of selection would co-operate with cessation of it.

This, as I understand it, is now exactly Weismann's view; only he thinks that thus the rudimentary organ would finally become extinguished. Here, however, it seems to me evident he must be wrong. The reasons are obvious, as I am going to show this week to my Edinburgh class. Six lectures are to be devoted entirely to Weismann, and when they are published (as they will be this time next year), I think it will be seen that Weismannism is not such very plain sailing as Weismann himself seems to think. Vines has anticipated some of my points in his paper in 'Nature'; but I hope this may have the effect of letting me see what answers can be given before I shall have to publish.

Yours very truly,

G. J. Romanes.