Charles Darwin

by Janet Browne

  Then he concentrated on bones, boiling up rabbit carcasses in an outhouse and measuring the skeletons, convinced that domestic rabbits ought to be bulkier in physique than the wild form. At long last, he found a use for the rabbits he had trapped on the island of Porto Santo, next to Madeira, and brought back alive from the Beagle voyage. In 1837 he had sent these to the London Zoo for display. Darwin got in touch with Bartlett again, asking him to kill two of them (“plenty more,” said Bartlett) and forward him the bodies. These, he imagined, were feral descendants of imported domestic breeds and ought to have reverted back to the wild type. Bone after bone, he built up his case. Generally speaking, these comparative measurements of rabbit bones required hours of patient work with graduated calipers and a microscope. In exasperation, he laid them out in rows on the Down House billiard table—his favourite table—to make sure that he really could see a chain of variations.

  And he returned to pigeons, finally producing a written account of the years of loving attention he had bestowed on them. The actual birds had been dispersed long ago. Even the old pigeon house had been moved away from the stable-yard and abandoned to ivy and the occasional child who might wish to play inside—although Darwin and Emma apparently had at first intended to climb the wooden ladder themselves and watch sunsets from its new vantage point on top of the wall by the kitchen garden.17 The most tangible relic of Darwin’s time as a pigeon-fancier was his set of dismembered skeletons and the dried skins of representative specimens. His pets had become data ready to be turned into ammunition.

  Every domestic pigeon, he claimed in Variation, was derived from a single ancestral species, the wild rock dove, or Columba livia. Many pigeon-fanciers, on the contrary, thought that some eight or nine wild species may be involved. “The amount of variation has been extraordinarily great,” Darwin agreed. “Formerly, when I went into my aviaries and watched such birds as pouters, carriers, barbs, fantails, and short-faced tumblers, etc., I could not persuade myself that all had descended from the same wild stock, and that man had consequently in one sense created these remarkable modifications.”18 But his breeding experiments convinced him it was so. Something of this ancestry could be seen in the way the characteristic black bars reappeared on the wings. Each highly developed breed carried within it the residue of its heritage. He said to Hooker it was rather like invisible handwriting that was revealed only at a later stage.

  With no birds left at Down House, Darwin necessarily experimented at one remove. He was assisted in this by William Tegetmeier, the naturalist who had previously helped him with similar work on domestic birds during the 1850s. Tegetmeier owned a diverse collection of prize-winning poultry and willingly supplied Darwin with information from his back yard in Wood Green, a suburb of London near Tottenham, carrying out matings between different breeds of chickens or pigeons, confirming results, inquiring among his poultry-owning friends about the validity of results, reading parts of Darwin’s manuscript, arranging artists to produce illustrations for Variation, and sometimes writing short articles about the Darwinian questions passing through his hands for publication under his own name elsewhere. At every possible point, Darwin consulted him about the implications these breeding experiments held for his theories.

  While it remains mysterious quite what Tegetmeier received from the relationship, apart from the claim to be working with an eminent figure like Darwin, Darwin certainly appreciated Tegetmeier’s help—he recognised that his statements would be an empty shell without Tegetmeier’s practical contribution. In letter after letter he oozed persuasive charm. “I am delighted to hear that you have the Fowls,” he wrote in February 1863.

  As soon as you have chickens you could kill off the old Birds. I shd. think the 3 ample.—It would be better to cross some cocks & Hens of the half-breds from the two nests; so as not to cross full brother & sister. I have not much hope that they will be partly or wholly sterile, yet after what happened to me, I shd. never have been easy without a trial.—I suggested Turbits [pigeons], because statements have been published that they are sometimes sterile with other breeds, & I mentioned Carriers, merely as a very distinct breed. I thought Barbs & Fantails bad solely because I had made several crosses & found the 1/2 breds perfectly fertile,—even brother & sister together. Did I send you (I cannot remember) a M.S. list of crosses; if so for Heaven sake return it.—I get slowly on with my work; but am never idle.—I much wish I could have seen you at Linn. Soc; but I was that day very unwell.—Pray do not forget to ask Poultry & Pigeon men (especially latter) whether they have ever matched two birds (for instance two almonds, Tumblers) & could not get them to breed, but afterwards found that both birds would breed when otherwise matched.—19

  I hope the world goes pretty well with you.

  Occasionally, charm gave way to impatience. “Have you quite thrown me overboard as too troublesome?” Darwin inquired a couple of years later. “I have not heard from you for an age.—I wrote some two months ago asking you to send as soon as you could any extracts & facts, which you told me you had collected, about number of sexes—Also any account of even one or two breeds of the fowl.—as colour of plumage of hen & chickens of Pile Game or Golden Hamburgh.—Will you not aid me so far?”

  In his own small way, Darwin was creating a private Garden of Eden, bringing back together the birds and beasts of the domestic world, either on paper or in the flesh, in order to discover their origins. “I am a complete millionaire in odd and curious little facts,” he told Hooker, “and I have been really astounded at my own industry.”20

  III

  Signs of Darwin’s activity were everywhere. Trays of seedlings stood about in sheds and outhouses. He dotted the kitchen garden with upturned flower pots, each protecting some hidden investigation. He covered Emma’s azaleas with unsightly netting just when they came into flower. It was important to use “net” for these, he said, the same material as on ladies’ hats, because a bell jar or cloche would create too much moisture. He raided Emma’s embroidery basket for coloured wools and silks to use as plant markers, and he shut Hooker’s exotic flowering orchids away in the study, saying they were for research rather than ornamenting the drawing room. From time to time he invaded Lettington’s and Brooks’s rows of runner beans to drape the plants with gauze, the purpose of which was unknown to everyone except the master. Darwin must have tested his gardeners’ patience during these experimenting years, for he was liable to step out from behind a bush when they least expected it, curtailing opportunities for leaning on a fork and taking stock of the surroundings. Daily, he issued instructions to his family and staff. “Cover that little Ervum in Sand-walk, on which I have never seen Bee visit,” he reminded himself, forgetting that the boys usually ran wild down there and could trample on a delicate experimental project.

  The family learned to live with his enthusiasms. Some of the children’s earliest memories were of helping Darwin with botanical experiments, and it was probably through these, and an increasing number of distinguished scientists visiting the house, that the youngest ones came to realise their father was famous. Leonard came home from his first term at Clapham School intent on reading the Origin of Species—the other schoolboys had presumably talked about it. “I remember my father entering the drawing room at Down, apparently seeking for someone, when I, then a schoolboy, was sitting on the sofa with the Origin of Species in my hands. He looked over my shoulder and said: ‘I bet you half a crown that you do not get to the end of that book.’ ” Leonard did indeed give up soon after. Darwin “won his bet but never got his money.”21

  At much the same time, George Darwin asked the school’s headmaster, Charles Pritchard, to “read with him” parts of Darwin’s Orchids and repeat some of the experiments at school. Pritchard was an enthusiastic botanist and noted astronomer, and he had a large conservatory at Clapham Grammar School built to his specifications that included a fernery. When Emma went to call at school (“on the buttering principle,” she said, with maternal foresight), s
he was given a guided tour of the hothouses, “which are very superior & full of curious & beautiful things especially the fernery.”22 Pritchard was probably pleased to encourage the sons of such an eminent author. “We succeeded in fertilising and ripening the seeds of Oncidium papillo [one of the hothouse species], but we did not succeed in our attempts to induce the seeds to germinate as his father challenged us to do.”23 To have Darwin’s sons at the school, and some direct scientific contact with Darwin himself, however slight, was—if discreetly handled—an excellent advertisement for Pritchard’s commitment to scientific education.

  Darwin included Henrietta and Bessy in some of his research. He and Henrietta studied the advertisements in the Gardeners’ Chronicle and Cottage Gardener and ordered a Wardian case (glasshouse) to stand in the bay window in the dining room, a complicated piece of Victorian engineering that was kept warm by placing dishes of boiling water under the frame.24 They intended keeping sensitive plants like the mimosa in it, for amusement on rainy days when they could not easily walk outside. “There is a mysterious box come for you, marked Glass but with a kind of gridiron lid as if it had something alive inside,” Erasmus wrote warily from London. The giant glass case was an expensive failure, however. Neither Darwin, nor the girls, nor Parslow could keep it hot enough. The begonias and “very curious Oxalis” with moving leaves that Hooker supplied soon died.

  All the time, absorbing new questions kept sidling in. He discussed the composition of manure with neighbours like Innes or Norman as if nothing could be of greater interest to him. He inquired into the parentage of cabbages as if they were wayward sons. He thought cordially about potatoes, remembering the wild Solanum he once gathered in the rain on Chiloè Island, and got his gardeners to plant eighteen eating varieties at Down so that the family could compare the shape and taste of the tubers on the table. He worried about infertility in the weeping beech. The effects of the environment on plants gave him much to think about. “I hardly know why I am a little sorry, but my present work is leading me to believe rather more in the direct action of physical conditions,” he remarked to Hooker. “Perhaps I shall change again when I get all my facts under one point of view, and a pretty hard job this will be.”

  In another aside, he lavishly praised the Down House gooseberries, poking fun at Hooker’s liking for these old-fashioned fruits. His children shared the repartee, saying they must curb their own appetites to ensure a good supply for their father’s friend. Francis Darwin said his earliest memories of Hooker involved this strange taste for gooseberries. “I clearly remember him eating gooseberries with us as children, in the kitchen garden at Down. The love of gooseberries was a bond between us which had no existence in the case of our uncles, who either ate no gooseberries or preferred to do so in solitude.”25 Darwin cultivated fifty-four varieties of gooseberry at Down House, a mere fraction of the hundreds available to European nurserymen, but still sufficient to occupy a substantial area in his fruit garden. Nearly all the varieties listed in the Gooseberry Register of 1862 that he discussed in Variation have long since disappeared.

  When Hooker came to Downe bearing gifts of bananas from the Royal Botanic Gardens, they were christened Kew gooseberries. “Do you not think you ought to be sent with Mr. Gower to the Police Court?” queried Darwin, eyeing one large bunch from the government’s greenhouses. “If Etty lets the Gooseberry season go bye without inviting me I will kill her,” Hooker quipped in return.

  Darwin also interested himself in the social relations of plants. He became inquisitive about weeds—always high on a gardener’s agenda. Considered in an abstract way, in the light of his theory, weeds were highly successful organisms. They were vigorous, invasive, competitive species, the very picture of health and adaptability. One sorry incident in the Sand-walk at Down House illuminated this much more than any theoretical reasoning could have done. The area had been planted by Darwin and Emma in 1843 or so, soon after their arrival in Downe, with a variety of native trees such as hazel, alder, lime, hornbeam, birch, and dogwood, to add to the well-established oaks and beeches that were already there, with a line of hollies down the exposed side next to the valley. Emma liked the natural look under the trees, with wood anemones and bluebells in their turn, set among clumps of wild ivy. She employed a young boy every now and then to pull up the dog’s mercury, an invasive, poisonous weed capable of advancing up to three feet a season. One year a new boy misunderstood the orders.

  As my father and mother reached the Sandwalk they found bare earth, a great heap of wild ivy torn up by its roots and the abhorred Dog’s mercury flourishing alone. My father could not help laughing at her dismay … and he used to say that it was the only time she was ever cross with him.26

  Darwin asked Asa Gray about the invasive properties of British weeds in the United States of America. Cocksfoot, a meadow grass, was at that time spreading fast through North American orchards, the epitome of an entrepreneurial, colonising species, and regarded by Darwin as representative of a more general, highly vigorous national spirit. British weeds were like British colonisers, he thought. “Does it not hurt your Yankee pride that we thrash you so confoundedly? I am sure Mrs. Gray will stick up for your own weeds. Ask her whether they are not more honest downright good sort of weeds.”27 He advised Julius von Haast to attend specially to invasive European species in New Zealand.

  Ceaselessly he returned to the intriguing problem of the sex lives of plants. Particularly, as he worked, he focused on what he and Huxley called “sterility,” the mechanisms that incipient species develop to prevent themselves blending back into the populations from which they emerge. This bore on the practical difficulties of keeping species apart. Unfortunately, most varieties could breed perfectly well with another variety of the same species, and it was hard to imagine how a population could ever keep itself sufficiently separate to turn into a new species without invoking some form of geographical or functional isolation. Huxley always mentioned the problem when he talked publicly about the Origin of Species. “To get the degree of sterility you expect in recently formed varieties seems to me hopeless,” Darwin expostulated to Huxley in December 1862. Nevertheless, that was precisely what Darwin was after.

  In particular, he brooded over the reproduction of Linum grandiflorum, the old-fashioned garden flax, a staple of Victorian flower beds, that has either a long or a short style inside its pink or scarlet flowers, a dimorphism which mirrored the pin- and thrum-headed primulas he had studied a year or two before. Darwin wondered if these anatomical differences would hold the clue to his problems. It did seem likely that long and short were mutually adapted to ensure cross-fertilisation. According to his theories, long-styled flowers would find it difficult to mate with other long-styled flowers, or short with short. Offspring might be reduced in vigour—a kind of incipient sterility.

  Much of this experimental work was tricky to perform. Although the flax species is considered a hardy annual in Britain, the plants required a heated bed. As he followed the fertilisation processes under his microscope, however, he was persuaded that he was witnessing a functional differentiation between otherwise identical flowers. The “reduced fertility” and “diminished vigour of the progeny” threw light on the nature of crossing and hybrids in general. He sent a paper on the subject to the Linnean Society early in 1863 and discussed it in Variation.

  He then set out to understand the three-way fertilisation patterns of the purple loosestrife, Lythrum salicaria. These complex plants made flax look like child’s play. “I am almost stark raving mad over Lythrum,” he cried to Gray.

  I cannot publish this year on Lythrum salicaria: I must make 126 additional crosses!! All that I expected is true, but I have plain indications of much higher complexity. There are 3 pistils of different structure & functional power & 3 kinds of pollen of different structure & functional power, & I strongly suspect altogether five kinds of pollen, all different in this one species!28

  Baffled, he asked his oldest son William to do
the mathematical calculations. William dutifully regarded this as no more tiresome than adding up columns of banking figures. Eagerly Darwin asked for more. Over the summer months of 1862, William recorded in a notebook dozens of investigations on his father’s behalf. He spent several weeks studying Lysimachia vulgaris (creeping jenny), comparing it with Lythrum for the relative length of stamens and pistil. He drew differently shaped pollen grains from Lythrum with the aid of a camera lucida and sent the measurements to his father. “Tuesday,” he said in early August, “I examined 102 plants this morning.” Many of these notes were intelligible only to Darwin and himself. “25 flowers examined from 5 different plants, of these 25, 113 had 5th stamen longest, 2 had 4 × 5, almost 5 had the pistil in contact or nearly so with 5th stamen, 10 had no points in them,” he reported to his father.29 In 1863 he worked his way through a long list sent by Darwin, headed “List of plants apparently adapted to prevent self-fertilisation.”