The correspondence of Charles Darwin, volume 18: 1870

Edited by Frederick Burkhardt, James A. Secord, Sheila Ann Dean, Samantha Evans, Shelley Innes, Alison M. Pearn, Paul White. (Cambridge University Press 2010)

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Introduction

The year 1870 is aptly summarised by the brief entry Darwin made in his journal: ‘The whole of the year at work on the Descent of Man & Selection in relation to Sex’ . Always precise in his accounting, Darwin reckoned that he had started writing on 4 February 1868, only five days after the publication of his previous book, Variation in animals and plants under domestication. In fact, Descent was the culmination of over three decades of observations and reflections on human ancestry, including the origin of language, mind, morals, and religious temperament. Research on sexual selection and emotional expression had predominated in recent years, and the information gathered on each of these topics was far more extensive than Darwin had anticipated. As a result, Descent, like Variation, would require two large volumes, and by June Darwin gave up the idea of including the material on emotion; it would eventually appear as a separate book in 1872 (Expression of the emotions in man and animals). The year was otherwise coloured by controversies, including vigorous objections to the application of natural selection to humans from Alfred Russel Wallace and St George Jackson Mivart, and heated debates sparked by Darwin’s proposed election to the French Academy of Sciences and his nomination for an honorary degree at Oxford. As usual, Darwin tried to avoid involving himself in such controversies, saving his energies for his scientific work and his family. As he was completing corrections to the final proofs of Descent in December, he wrote to his friend Charles Lyell, ‘thank all the powers above & below, I shall be a man again & not a horrid grinding machine’  (letter to Charles Lyell, 25 December [1870]).

Darwin began receiving proofs of some of the illustrations for Descent as early as January, including woodcuts of the heads of chameleons and the tail feathers of snipe, much to his delight: ‘The sight of the proofs has pleased me more than anything which has happened to me for some weeks’  (letter to Albert Gu?nther, 13 January [1870]). Darwin was still working hard on parts of the text, in particular his chapters on the moral sense and the comparative mental powers of humans and animals. He turned, as he had before, to his daughter Henrietta for commentary, sending her parts of the manuscript while she was on holiday in France and Italy: ‘After reading once right through, the more time you can give up for deep criticism or corrections of style, the more grateful I shall be’  (letter to H. E. Darwin, [8 February 1870]). She had previously read proof-sheets of Variation and Orchids, the latter when she was just eighteen years of age. CD clearly expected her to make a considerable contribution, instructing her to write any long corrections on separate slips of paper pinned to the relevant page of manuscript. He worried that parts of the book were ‘too like a Sermon: who wd ever have thought that I shd. turn parson?’ (letter to H. E. Darwin, [8 February 1870]). Henrietta disagreed: ‘Certainly to have you turned Parson will be a change I expect I shall want it enlarging not contracting cos I think you think an apology is wanting for writing abt any thing so unimportant as the mind of man!’ (letter from H. E. Darwin, [after 8 February 1870]). Darwin was also encouraged to expand his discussion of mind and morals by the religious writer and philanthropist Frances Power Cobbe. At Cobbe’s suggestion, Darwin read some of Immanuel Kant’s Metaphysics of ethics, and he remarked on the contrast between the ‘great philosopher looking exclusively into his own mind’, and himself, ‘a degraded wretch looking from the outside thro’ apes & savages at the moral sense of mankind’ (letter to F. P. Cobbe, 23 March [1870?]). Cobbe accused Darwin of smiling in his beard with such remarks, and urged, ‘are you never going to unite your lines of thought & let us see how metaphysics & physics form one great philosophy?’ (letter from F. P. Cobbe, 28 March [1870?]).

Despite Cobbe’s plea, most of Darwin’s scientific attention in 1870 was devoted to the ‘physical’ side of human descent. On 7 March 1870, Darwin made a note on the shape of human ears: ‘W. has seen the tips in women & men. When he was making his figure of Puck he went to Z garden and made drawings of ears of monkeys & shortly afterwards he saw a man with tip & instantly recognized their signification’  (DAR 80: B120). The reference here is to the sculptor Thomas Woolner, and to his statue of Puck, the mischievous fairy in Shakespeare’s A midsummer night’s dream. Darwin obtained a sketch of a human ear from Woolner showing the unusual feature of a pointed tip projecting inward from the folded margin. Darwin, who had posed for the sculptor in 1868, an experience he described as ‘purgatory’ made lighter by Woolner’s ‘wonderfully pleasant’ manner, named the feature after the famous artist. ‘The “Woolnerian tip” is worth anything to me’, he wrote in thanks for the drawing (Correspondence vol. 16, letter to J. D. Hooker, 26 November [1868]; this volume, letter to Thomas Woolner, 10 March [1870]). Darwin included Woolner’s sketch in Descent, and discussed the ‘tip’ as a rudimentary organ, describing its frequency and variability in humans (Descent 1: 22-3).

A more troubling anatomical feature for Darwin was the platysma myoides, a band of muscle in the neck extending from the collar bone to the lower part of the cheek. Darwin had read various accounts of the contraction of this muscle in persons experiencing fear or terror. He studied the photographic album by the French physiologist Guillaume Benjamin Amand Duchenne, whose research involved the mechanical production of expressions by applying electrodes directly to the face and neck. Duchenne had dubbed the platysma the ‘muscle of fright’, and one of his photographs, later used by Darwin in Expression, showed a man whose platysma was severely contracted, his face exhibiting extreme horror. Darwin lent Duchenne’s album to the asylum director James Crichton-Browne, who had become one of Darwin’s most avid observers of facial expression. Browne sent a lengthy account of the movements of the platysma muscle in his asylum patients, but it did not confirm Duchenne’s findings (letter from James Crichton-Browne, 15 March 1870). Indeed, Darwin noted the same longitudinal furrows radiating on the side of the neck of his son Francis when he was playing the flute. Exasperated, Darwin turned to the physician and eye-specialist William Ogle, requesting him to observe the muscle in patients who were having trouble breathing. ‘This muscle’, he complained, ‘is the bane of existence!’ (letter to William Ogle, 9 November 1870).

Darwin’s research on emotions continued to draw on observations from a variety of domains, from the colonial frontier to the household, from the photographer’s studio to the zoological garden. He received more replies to his questionnaire on expression, including four lengthy letters from the explorer William Winwood Reade, who had led an expedition to Africa in search of the source of the Niger river. Reade was sceptical of Darwin’s view that standards of beauty were variable across different cultures and claimed that Africans admired the racial characteristics of Europeans. The nose, he remarked, was ‘the only doubtful point . . . girls have been heard to say “I dont want to marry him he’s got no nose”. Reade noted the strong preference of native peoples for black skin, but attributed this to their belief that all demons and spirits were white (letter from W. W. Reade, 9 November 1870).

Keen for more evidence of the continuity of expressions across species, Darwin asked the zoo-keeper at Regent’s Park to study the squirrel monkey’s screams: ‘does it wrinkle up the skin round the eyes like a Baby always does? . . Could you make it scream without hurting it much?’ (letter to A. D. Bartlett, 5 January [1870]). Darwin made a similar request of a London photographer: ‘I have been trying to get a [photograph] of a young baby screaming or crying badly; but I fear he will not succeed’ (letter to James Crichton-Browne, 8 June [1870]). Darwin’s queries were part of an investigation into the physiology of weeping that had begun with observations on his own children as early as 1839. Darwin now recruited family members with infants, including his niece Lucy Wedgwood, who sent a sketch of a baby’s brows (letter from L. C. Wedgwood, [5 May 1870]). He also wrote to a leading Dutch ophthalmologist, Frans Cornelis Donders. In order to fulfil Darwin’s request, Donders undertook painstaking experiments on the operation of the eye muscles in weeping. He wrote to Darwin when his work was interrupted by the death of his daughter in childbirth: ‘We are living with a sorrow which it seems can never end, and . . . I have found it hard to return to the laboratory and to attend to our occupations. . . . I have examined the circulation of the eye with some care, and all I am lacking is the inclination to finish my note on this subject’  (letter from F. C. Donders, 17 May 1870).

While Darwin was still revising his manuscript of Descent, the public debate over human evolution grew more heated. Alfred Russel Wallace had expressed reservations about the application of natural selection to the development of the higher intellectual faculties of humans the previous year (see Correspondence vol. 17, letter to A. R. Wallace, 14 April 1869). His views were presented more fully in a collection of essays published in April 1870 (Wallace 1870a). Wallace wrote to Darwin in January warning him of the impending publication. Darwin joked about Wallace’s own intellectual descent: ‘I groan over Man – you write like a metamorphosed (in retrograde direction) naturalist’ (letter to A. R.Wallace, 26 January [1870]). Despite their increasing theoretical differences, both men worked as they had in the past to sustain goodwill and mutual respect. Wallace’s new book, titled Contributions to the theory of natural selection, was dedicated to Darwin. When he received the book, Darwin was full of praise for Wallace’s ‘modesty and candour’. ‘I hope it is a satisfaction to you to reflect, – & very few things in my life have been more satisfactory to me – that we have never felt any jealousy towards each other, though in one sense rivals’ (letter to A. R. Wallace, 20 April [1870]). Darwin alluded here to the famous events of 1858,When Wallace had communicated his own version of the theory of descent by natural selection in a letter to Darwin, prompting much anxiety on Darwin’s part over his priority of discovery.

While Darwin and Wallace remained on amicable terms, other supporters of Darwinian theory were concerned about the consequences of Wallace’s book. Henry Walter Bates urged Darwin to respond to it directly in the form of a review: ‘I have been having some conversation with the Editor of the “Academy” about Mr Wallace’s last book & the appearance of backsliding from the Darwinian theory which it contains. . . . The views of friend Wallace are so plausible & suit so well wide-spread prejudices that you no doubt think with me they ought to be controverted. But who is to criticise them? No one but yourself’ (letter from H. W. Bates, 20 May 1870). Darwin very rarely used the periodical press to reply to critics, preferring to address what he considered to be important objections in the revised editions of his own publications. To Bates, he pleaded lack of time and weak health: ‘my chief reason is that I really have not a grain of spare strength. . . . You wd. not readily believe how often & urgently I am pressed to write articles . . . & it is an immense relief to me to be able to say that I never write reviews’ (letter to H. W. Bates, [22 May 1870]).

Another set of objections to the extension of natural selection to human evolution came from the zoologist St George Jackson Mivart. A protégé of Thomas Henry Huxley, Mivart had established a reputation as a leading comparative anatomist through his work on primates. In July 1869, Mivart published the first of a series of articles, titled ‘Difficulties of the theory of natural selection’, in the Roman Catholic journal the Month. He argued that a number of physical structures and homologies could not have arisen through the operation of natural selection alone, and that these were better accounted for by an underlying design. Darwin commented on Mivart’s essay in a letter to William Henry Flower: ‘I am glad you noticed the curiously false argument in the Month. . . . I cd have answered, I think satisfactorily, many of the objections advanced in this article; but my whole time wd be wasted if I once began to answer objectors’ (letter to W. H. Flower, 25 March [1870]). In his letters to Mivart, Darwin remained cordial and supportive, praising his earlier anatomical papers and urging him to resume his research: ‘I hope that you will continue your wonderfully laborious & valuable labours on the Primates’ (letter to St G. J. Mivart, 23 April [1870]). He also tried to recruit Mivart’s expertise, and inquired after a point of human and ape anatomy, hoping to cite Mivart as an authority in Descent. Mivart’s reply, however, underscored their fundamental differences on human ancestry: ‘assuming that zoological classification should be Anatomical– Man forms only a family of the higher division of the Primates. But if we introduce into the consideration his intellectual, moral & religious nature I am convinced he differs more from an Anthropoid Ape than such an Ape differs from a lump of granite’ (letter from St G. J. Mivart, 22 April 1870). Mivart hinted that his criticism of descent theory was not directed at Darwin himself, but at more aggressive champions of Darwinism: ‘For my part I shall never feel anything but gratitude & sincere esteem for the author of “natural selection” but I heartily execrate some who make use of that theory simply as a weapon of offence against higher interests and as a means of impeding Man’s advance towards his “end” whatever may have been his “origin” (letter from St G. J. Mivart, 25 April 1870). In his critical essays (later revised as Genesis of species (Mivart 1871)), Mivart tried to carve out a position between the new evolutionary biology that was being promoted by Huxley and others as an instrument of social reform, and another constituency to which he was equally loyal, the Roman Catholic Church. The relationship between Mivart and Darwin would grow more strained in the next few years and eventually reach breaking point.

Darwin’s name and theory served a number of polemical and political ends. In France, Darwin was proposed for a corresponding membership of the elite Academy of Sciences, prompting an extended debate. The nomination was made by Henri Milne-Edwards and Armand de Quatrefages, both leading zoologists in Paris. Quatrefages had just completed a book, Charles Darwin et ses précurseurs français (Quatrefages 1870), that gave a detailed account, as well as criticism, of Darwin’s theory. On receiving the book, Darwin remarked, ‘many of your strictures are severe enough, but all are given with perfect courtesy & fairness. I can truly say I would rather be criticised by you in this manner than praised by many others’  (letter to Armand de Quatrefages, 28 May [1870]). Quatrefages had corresponded with Darwin regularly since 1859, and viewed his relationship with Darwin as embodying the virtues of scientific community, placing truth above individual or factional differences. ‘Yes, I dare to say it,’ he wrote, ‘we are both pursuing truth and that alone must establish links between us which are stronger than the causes of discord’  (letter from Armand de Quatrefages, 30 March 1870). In proposing Darwin for election, Quatrefages hoped to bring the same non-partisan spirit into the French Academy, ‘rest assured that I shall be a zealous and convinced advocate. . . . Our very dissensions will give more weight to my words’. In fact, the election served as an occasion for attacks not only on Darwin’s theory, but on his scientific methods and his status as a naturalist. ‘It is being said at the Academy’, Quatrefages complained, ‘. . . that you had done no more than collect natural history specimens and that you had called on assistants to describe them’  (letter from Armand de Quatrefages, 18 July 1870). The assertion had been made by Emile Blanchard, who added that Darwin’s pigeon studies were unscientific, and that his various theories, from coral island formation to transformism, were either unoriginal or false. Another detractor, Léonce Elie de Beaumont, referred to Darwin’s work as ‘la science mousseuse’ (a science of froth or bubbles). Quatrefages himself seemed uncertain about some of these charges, and he seemed unaware that Darwin had published any of his geological research from the Beagle voyage.

Darwin lost the election by a narrow margin. The defeat was seized upon as a matter of national pride by the Belgian zoologist Edouard van Beneden when the Belgian Academy elected Darwin an associate member later that year. ‘In this matter the Belgians have taught the members of the Institut de France a lesson,’ he wrote. ‘May all the learned bodies of the world protest, like the Academy of Belgium, against the debate they dared instigate on the question of your scientific merits. Your name summarises the whole scientific movement of recent years and your immortal work is above all attacks’  (letter from Edouard van Beneden, 17 December 1870). A more parochial controversy occurred in Oxford, when Darwin was chosen to receive an honorary degree. Among the other candidates had been Thomas Huxley, who wrote to Darwin about the heated debate that had taken place in the ruling body of the University, and the role played by a leading Anglican conservative, Edward Bouverie Pusey: ‘There seems to have been a tremendous shindy in the Hebdomadal board about certain persons who were proposed; and I am told that Pusey came to London to ascertain from a trustworthy friend who were the blackest heretics out of the list proposed – and that he was glad to assent to your being doctored, when he got back – in order to keep out seven devils worse than that first!’ (letter from T. H. Huxley, 22 June 1870). In the event, Darwin did not receive the degree because it could only be awarded in person, and he declined to attend the ceremony on grounds of weak health: ‘I could have travelled to Oxford,’ he confessed, ‘but could no more have withstood the excitement of a commemoration than I could a ball at Buckingham Palace’ (letter to B. J. Sulivan, 30 June [1870]).

Though Darwin was mostly occupied with the revision of Descent and research on expression, his attention was frequently diverted by correspondents to topics of long-standing interest. The Italian botanist Federico Delpino sent a description of a pollination mechanism in Lotus siliquosus (now L. maritimus), a sample of which had been collected by one of Darwin’s sons: ‘This . . . apparatus, which I have called “papilionaceous pump apparatus” is rather marvellous. It is similar to the instrument with which one makes pasta at the vermicelli-makers.’  Bees settling onto the carina of the flowers caused the pistil and filaments to press upon the pollen-mass, which was then ejected through a small hole in the carina and attached to the insects (letter from Federico Delpino, 20 May 1870). Darwin encouraged the German naturalist Hermann Müller to continue his work on the adaptation of insect structures, in particular the mouth-parts of bees, to the forms of flowers: ‘As far as I know, no one has carefully observed the structure of insects in relation to flowers, although so many have now attended to the converse relation’ (letter to Hermann Müller, 14 March 1870). Darwin received a string of letters from his cousin Francis Galton, reporting on his efforts to alter the colour of rabbits by transfusing the blood of one variety into another and observing the colour of the offspring. The experiments, designed to test Darwin’s hypothesis of pangenesis, sometimes involved unusual procedures: ‘I hope to succeed in making the ears of two young rabbits grow together & to mix their circulations by breaking adjacent veins into one’ (letter from Francis Galton, 25 June 1870). Occasionally Galton reported success: ‘Good rabbit news.! One of the latest litters has a white forefoot’  (letter from Francis Galton, 12 May 1870). But in general the results were discouraging. Darwin’s pangenesis theory also prompted speculation among some of his correspondents about the influence that males could have, both upon later generations of offspring not sired by them, and upon the females with whom they had mated. Some thought that male ‘gemmules’ (the material of hereditary transmission in Darwin’s theory) might be transmitted to the female by the circulation of blood between the mother and foetus during pregnancy. As a case in point, John Jenner Weir described the offspring of a mare that had once mated with a quagga as resembling a donkey; he also added: ‘It may be fanciful on my part but I cannot but think that my theory accounts for what has been so often noticed that persons long married grow like each other’ (letter from J. J. Weir, 17 March 1870). With Joseph Dalton Hooker, Darwin discussed the recent experiments of Henry Charlton Bastian, which Bastian claimed showed evidence of the spontaneous generation of life from inorganic matter: ‘Spontaneous generation seems almost as great a puzzle as preordination; I cannot persuade myself that such a multiplicity of organisms can have been produced, like crystals, in Bastian’s solutions of the same kind’ (letter to J. D. Hooker, 12 July [1870]). Bastian’s results were criticised in a presidential address to the British Association for the Advancement of Science by Thomas Huxley, who had identified bits of the moss Sphagnum in Bastian’s supposedly empty and sealed test tubes. Huxley’s address also discussed recent experiments by Louis Pasteur and John Tyndall that provided evidence for the existence of germs.

Some of the wider implications of evolutionary theory for medicine and society were explored in a campaign that Darwin initiated to gather information about the potentially harmful effects of cousin marriage. Darwin wanted to test the prevalent assumption that marriages to first cousins were injurious to offspring. He wrote initially probably to Henry Hussey Vivian, an MP and fellow of the Geological Society: ‘I have every cause to believe that the time will soon come, when this subject will be . . . highly important for the welfare of mankind’ (letter to [H. H. Vivian?], [April or May 1870?]). Vivian contacted the home secretary, Henry Austin Bruce, about the possibility of inserting a question in the 1871 census about cousin marriage. Darwin believed that if such statistics could be obtained, they could be correlated with figures regarding the frequency of deafness, blindness, and other conditions in the offspring of consanguineous marriages. He enlisted the support of William Farr, a specialist in medical statistics who worked in the registrar-general’s office, in drafting a memorandum. He asked his neighbour, the naturalist John Lubbock, who was now MP for Maidstone, to present the proposal to the House of Commons. Lubbock read Darwin’s letter before the Commons on 26 July, ‘As you are aware, I have made experiments on the subject during several years; & it is my clear conviction that there is now ample evidence of the existence of a great physiological law, rendering an enquiry with reference to mankind of much importance’ (letter to John Lubbock, 17 July 1870). The motion to amend the Census was defeated by a vote of ninety-two to forty-five.

As was usual in periods of reasonably good health, Darwin seldom took breaks from his scientific work except to receive friends and visit family. He confided to his cousin William Darwin Fox, ‘I never pass 6 hours without a fit of extreme discomfort, & so I shall go on to the last of my uncomfortable days’ (letter to W. D. Fox, 18 February [1870]). But he had resumed horse-riding and, subject to the usual qualifications, Darwin’s health was generally good. He did consult Henry Bence Jones, his physician since 1865, regarding ‘pins & needles’. Jones replied, ‘some stopped molecular action I suppose which is somehow related to your indigestion. Altho’ the manner is very dark to me and to every one else I suspect’ (letter from H. B. Jones, 2 August 1870). Darwin had visits from a number of scientific friends and colleagues at Down, including Alexander Agassiz and his family, Anton Dohrn, Albert Günther, Joseph Hooker, Rudolf Albert von Kölliker, Alfred Newton, Robert Swinhoe, and Vladimir and Sofia Kovalevsky. In November, he received a permanent guest in the form of a Scottish deerhound puppy, the pride and joy of George Cupples, who had written to Darwin regularly over the course of the year to apprise him of the dog’s progress and fine breeding: ‘the father is descended from Sir Walter Scott’s celebrated “Maida”’ (letter from George Cupples, 17 September 1870). Darwin reassured Cupples after the dog arrived, ‘Bran is thriving & growing at a wonderful rate – coat sleek, & not too fat. Plays much with Polly & enjoys English life’  (postcard to George Cupples, 27 November [1870]). In addition to receiving many visitors, Darwin was also away from Down more than usual, staying on three occasions in London with his brother Erasmus, a week in Surrey and at Ightam Mote, in Kent, and nearly a fortnight with his son William in Southampton, and making a four-day visit to Cambridge. While in Cambridge, he toured the Woodwardian Museum with his former professor of geology, Adam Sedgwick. ‘He utterly prostrated me,’ Darwin wrote to Hooker, ‘. . . & I have not recovered the exhaustion yet. Is it not humiliating to be thus killed by a man of 86’  (letter to J. D. Hooker, 25 May [1870]). On learning of this, Sedgwick replied: ‘I was truly grieved to find that my joy at seeing you again was almost too robust for your state of nerves. . . . I only speak honest truth when I say that I was overflowing with joy when I saw you; & saw you in the midst of a dear family party & solaced at every turn by the loving care of a dear Wife & Daughters. How different from my position – that of a very old man, living in cheerless solitude!’ (letter from Adam Sedgwick, 30 May 1870).

Darwin continued to take great pride in his children, and to worry about any potential waywardness on their part. He reflected on the responsibilities of finding a course in life for one’s sons to Hooker: ‘God knows it is puzzle enough in every case whatever; & what our Boy Horace is to do, I know no more than the man in the moon’ (letter to J. D. Hooker, 25 May [1870]). Horace had entered Trinity College, Cambridge, in the autumn of 1870. Darwin was concerned that his poor health in previous years had left him behind, and arranged for him to have private instruction in mathematics. He wrote to Horace’s tutor at Trinity to request that he be excused from attending college lectures for the time being (letter to [E.W. Blore], [October 1870 or later]). Leonard continued to have great success in the army. He gained a commission in the Royal Engineers, obtaining the second highest marks among the candidates. Francis completed his studies at Cambridge, taking third place in first-class honours in the natural sciences tripos in December. He had fallen into debt, however, and had kept the matter secret for some months. Darwin was very stern in his advice: ‘I have never known a man who was too idle to attend to his affairs & accounts, who did not get into difficulties; & he who habitually is in money difficulties, very rarely keeps scrupulously honourable. . . . My father, who was the wisest man I ever knew, thought it the duty of every man, young & old, to keep an account of his money; & I very unwillingly obeyed him; for I was not always so bothersome an old fellow as I daresay I appear to you’ (letter to Francis Darwin, 18 October [1870]). The affection and concern of the father for his children were reciprocated. George, who was now a fellow at Trinity College, Cambridge, wrote to Henrietta of his concern that his father, despite suffering a bad fall the previous year, continued to ride the same horse that had thrown him (letter from G. H. Darwin to H. E. Darwin, [21 – 2 February 1870] (DAR 251: 2243)). With some difficulty, he had found a mare so tame that she was ridden by a blind man and used at a school for timid riders. ‘She has a canter like an armchair’, he informed his father (letter from G. H. Darwin, [3 February 1870 or earlier]). George devoted considerable effort to securing the loan of the animal for his father, but the horse did not suit Darwin, and he evidently continued to ride the dangerous Tommy.

Darwin’s European correspondence was disrupted for part of the year owing to the outbreak of war. France had declared war on Prussia on 19 July 1870, and French troops had crossed the border into Prussia at the end of that month. But despite suffering heavy casualties, the Prussian armies won several decisive victories in August. Darwin followed the progress of the war in the press, and to his German correspondents he declared his allegiance to the Prussian cause. ‘I cannot express too strongly how I rejoice at the wonderful success of Germany,’ he wrote to Julius Victor Carus, ‘& I have not hitherto met a single person who has not entirely participated in this feeling’  (letter to J. V. Carus, 18 August 1870). Carus described how he had to abandon his work to care for the wounded, and how he found some ‘philosophic comfort’ in viewing the war as a ‘necessary consequence of natural conditions’, ‘a most dreadful “struggle for existence”’ (letter from J. V. Carus, 2 October 1870). Carus, who had already arranged to translate Descent into German, assured Darwin that the war would not interfere with the success of his book in Germany: ‘People are anxious to find a safe refuge in science’.

As completion of the book drew near, Darwin began to prepare for its reception, and for the disapproval that would greet his conclusions about the ‘origin of man’. ‘I can most truly say’, he wrote to his cousin William Darwin Fox, ‘that I have written nothing without deliberate consideration & acquiring all the knowledge which I possibly could. – I will send it, as I know well that you are a charitable man & do not without good evidence believe in bad motives in others’  (letter to W. D. Fox, 15 November [1870]). Fox reassured him, however, that descent from a monkey was no longer so hard to contemplate, for he had recently learned from the antics of the orang-utans at the Zoological Gardens in Regent’s Park that beasts shared the same vices as humans: ‘the Lady Monkey from the Andamans – drinks & smokes like a Christian; & evidently the Gentleman wd thrash, if not kill the Lady, if he had an opportunity’  (letter from W. D. Fox, 18 [November 1870]).

This volume contains a supplement of more than one hundred letters that have been discovered since the volumes they should have appeared in were published, or that have been redated to before 1870. It also contains some letters with wide date spans that were probably written before 1870. The supplement includes letters to William Kemp between 1840 and 1843, concerning Kemp’s geological discoveries in Scotland; letters to the Arctic explorer John Richardson thanking him for barnacle specimens; a letter to Charles Kingsley written shortly after the publication of Origin; and letters to Henry Fawcett thanking him for his favourable review of Origin, and reflecting on the methodological and theoretical difficulties of Darwin’s early research on species.