Darwin and the Barnacle
Page 27
Darwin found himself sharing many of Gosse’s ideas and passions. His Preface to A Naturalist’s Sojourn was brave and assertive for a man entering the word of zoology. He had begun this first major book with a clarion call, challenging zoologists to abandon the study of dead and dried things and instead commit themselves to the study of live creatures. He was even now, people said, working on finding a chemical formula to produce artificial seawater so that naturalists could study live sea creatures in glass tanks instead of just dissecting them. This was a different zoology – a humane one, admittedly, but a world away from the philosophical problems of anatomical structure and shape-shifting that so taxed Darwin. Gosse was interested only in the here and the now of the creatures he studied, not in how they had come to be.16
Joseph Hooker and his wife Frances came to stay at Down in April, the week in which the family would pass the first anniversary of Annie’s death. It would be a distraction for them all, for the children loved their father’s friend, and it gave Darwin an opportunity to cross-question Hooker on the problems of classification now facing him. Frances watched Joseph playing with the Darwin children, down on the floor throwing pillows, playing at bears, imagining herself at the centre of such a family, a family that they could not begin until Joseph had secured himself a position, she told Emma. On the anniversary of Annie’s death, Emma, grieving and melancholy, suggested that they all walk to the top field to fly George’s new kite, but in high winds the new kite tangled in the tall trees, tearing its coloured silk into ribbons. Emma was resourceful as always, the Hookers marvelled: while she comforted George, Parslow climbed the tree to rescue the tattered kite. She would mend it, she reassured George. All would be well: the kite would fly again.17
Hooker had now completed much of the classification of the New Zealand plants and had begun to think about writing an introductory essay that would deal with the philosophical problems facing the botanist. Darwin was impatient to know how Hooker would conclude, how he would represent these insurmountable problems but he reminded Hooker that he must say nothing of the species theory in this introduction – not yet.18 He was sworn to secrecy. Darwin was excited, Hooker exasperated. How could he keep natural selection out of the introduction when it explained so many of the variations in New Zealand flora? There were other obstacles to publication, too, for a philosophical botanist such as himself: no one could even begin to speculate on the species theory, he complained, until the competing naming methods settled into a common system that would at least mean that zoologists and comparative anatomists were speaking the same language, not this current tower of Babel dominated by ignorant noodles who couldn’t tell a cabbage from a cabbage palm.19
During Hooker’s visit the two men spent long hours discussing the implications of Hooker’s difficulties with classifying the flora from New Zealand, after breakfast in the study, or later in the day, strolling round the Sand Walk, Etty or George in tow. Pumping, Darwin called it; he was pumping Hooker, drawing upon his knowledge, forcing him to confront certain theoretical problems.20 As their shared questions settled into shape, Darwin formulated a list of seven points for discussion and wrote them out as a memorandum for Hooker to take away with him: ‘Questions for Hooker’, he titled it. They were thinking through the same set of questions about the variability and distribution of species, with Hooker representing the Vegetable Kingdom and Darwin representing the Animal Kingdom. It was a rare event. The questions formulated by Darwin at Down, annotated and answered where possible by Hooker, passed backwards and forwards between them for months. These were exciting times: anything was possible. This secret sharer, mountain climber, rhododendron hunter, border crosser, man of courage – would he stand by the species theory when it came under attack?
Now that the Ibla and Scalpellum stories were out, Darwin waited with bated breath to hear whether they would be believed by the subscribers to the Ray Society. In addition he had sent out almost all his twenty complimentary copies to the most important international zoologists working on marine matters, and awaited their verdict. Letters began to arrive slowly, but the approval was strong and unwavering. He was being believed, despite the hesitating and provisional nature of his conclusions about the complemental males. Johannes Peter Müller wrote from Berlin, then James Dana from America. Their congratulations gave him the heart to go on, he replied. Then Professor Richard Owen wrote in July with approval that was essential if the books and their theories were to be well received in London circles. Darwin was gratified and grateful for the endorsement, though he was happy to confess that he could see weaknesses in his accounts of the living stalked barnacles: he had not given over enough time to the anatomical part, he feared, because he had been anxious about time. He was none the less delighted by Owen’s letter: ‘Pray believe me in a great state of triumph, pride vanity, conceit &c &c &c, Yours sincerely, Charles Darwin.’21
Whilst he had thought that ‘the only part worth looking at [was] on the sexes of Ibla and Scalpellum,’22 he was being commended for having discovered the homologies of the shell and the external part of cirripedes as well, discoveries that had been long awaited by comparative anatomists. In the late 1830s the French comparative anatomist, Henri Milne Edwards, had worked out that an archetypal crustacean has twenty-one segments or body parts. When Vaughan Thompson discovered the metamorphosis of the barnacle from free-swimming larva to fixed adult at about the same time, the way was clear for a careful observer to map the barnacle anatomy against the twenty-one segments of Milne-Edward’s archetypal crustacean. This was one of the tasks Darwin had undertaken from the start, but was only part-way through by the publication of the 1851 volumes, for although he had been able to find seventeen of the crustacean segments represented in barnacle bodies, four were missing. This meant that he had a method by which to compare body parts – it gave him a basic plan against which or over which he could plot his ‘deviants’, like Mr Arthrobalanus, in order to see how and where they had diverged from the crustacean body plan. Then, of course, he could speculate about what evolutionary advantage this deviation might have given them. Mutation of body parts meant that the living creature could accommodate new functions: what might once have been a pair of limbs for walking might elsewhere have transformed into cirri for feeding for instance. Other organs, such as the missing abdominal segments, might simply have atrophied over millions of years of non-use. Nature had simply rearranged the body parts of an archetypal crustacean over thousands of years to fit it for new conditions.
Sleepless and racked by toothache in June, Darwin read Dr Henry Holland’s new book Chapters on Mental Physiology. Holland, too, was taking risks and being tentative about them – these were notes, he insisted in his introduction, not a complete treatise and the ‘topics treated of are such in their nature as perpetually to bring us to the very confines of metaphysical speculation’. He wanted to explore the influence of the mind over the body, particularly the bearings of mental action upon ‘morbid disease’ either ‘directly or indirectly – as cause or as effect’.23 Unlike many of his peers, Holland was also a border crosser, like Darwin, convinced that there were no absolute lines to be drawn between mind and body, nor between certain mental states such as sleep and wakefulness: ‘Take … a person seeking rest on an easy bed, or under the influence of pain or disordered digestion. Obviously to himself, as those around him, there is an incessant alteration of state, testified by various bodily movements, by partial consciousness of external objects, by dreams broken and renewed – a strange interlacing of the two conditions, which thus divide our existence.’24
However, whilst Holland was clearly excited by new biological ideas and medical practices, and accepted the flux of nature and of mental states, even showing his understanding of the debates about the mutability of species, he concluded that there simply was not enough evidence so far to prove any of these ideas as anything more than speculations.25 Two days later Darwin experienced his first deep and unfluctuating sleep in months: his Lon
don dentist, Mr Waite, put him under chloroform so that he could extract five teeth.26 It cost Darwin a guinea, he wrote to Fox, but it was worth it for ‘this wonderful Substance’.
Above all, he was – tired tired of the sleepless nights, of the Water Cure regime, of the barnacles more than anything, though they had still not finished tormenting him, he wrote to Fox in October: ‘I am at work on the second vol of the Cirripedia, of which creatures I am wonderfully tired: I hate a Barnacle as no man ever did before, not even a Sailor in a slow-sailing ship.’27
His ship – his barnacle-encrusted volumes – was excruciatingly slow-sailing. This time he was determined not to be further slowed down by a tardy illustrator. He had employed another Sowerby for the illustrations for the third volume, George Brettingham Sowerby Jr, the nephew of James Sowerby, who had been so frustratingly slow. George was less of an artist but more efficient. Darwin had even invited him to Down House for a two-week visit so that they could work together on the drawings for the third volume. These were Herculean labours, and yet the most difficult of all the barnacle territories still lay ahead. Turbulent seas: something had to yield. A few months before, on 22 August, he had decided to give up the Water Cure regime, which he had only been continuing in a rather intermittent way since Annie’s death the previous spring. It did not seem to be bringing the results that it had done the previous year, and as winter was not so far off, it seemed a good time to give up the cold torture.28 His health, mysteriously, improved quite dramatically throughout the last months of the year, giving him renewed vigour to face the last deviant barnacles.
John Lubbock was a welcome presence during these labours, working alongside Darwin in his study for a few hours every few days.29 The eighteeen-year-old had been working on crustacea most of the year with his new microscope, and now Darwin had given him the task of dissecting and drawing water fleas, a transparent crustacean called Daphnia, which swarmed in Down Pond. In November John began a new natural history notebook recording: ‘Took my work up to Mr Darwin and after coming home copied out neat a good deal of what I could say about it.’30 The water fleas, like Darwin’s Ibla and Scalpellum, had inventive reproductive patterns: they were almost exclusively female, reproducing by asexual methods; but occasionally, when conditions were poor owing to a lack of food, low oxygen supply, a high population density, or low temperatures, they would produce males and reproduce sexually. John Lubbock was using a camera obscura up at High Elms so that he could draw infusoria from nature, and his drawings were becoming remarkably accurate, Darwin noted with pleasure, all the more aware of the limits of his own drawing skills. John would be ready to publish some of his discoveries on Darwin’s crustacean collection soon, particularly his discovery of new species of Labidocera and Calanidae.31 Darwin was ambitious for his young friend and was keen to help his career as a naturalist. When James Dana wrote to tell him that he had completed his three-year crustacean research, Darwin wrote to congratulate Dana but also to commend his young friend: ‘I have a neighbour, who is very anxious to see this work; he is the son (very young) of Sir J. Lubbock, the great astronomer & Banker, who has taken up the smaller Crustacea with great zeal, & will soon publish a paper on a subgenus of Portia.’32 He would now write to the editors of the Annals of the Magazine of Natural History on John’s behalf.
Darwin had still to return to the problem of how and why barnacles had evolved burrowing powers – why had these groups, found in very different places around the world, developed the ability to make their homes in the bodies of sharks or in the cavities of rocks, rather than secreting their own houses around them like other sessile barnacles? How did they fit into the barnacle world? It was now time for Mr Arthrobalanus, Verruca and Alcippe, to step back on to the microscope stage and time, too, to renew correspondence with the Newcastle naturalist, Albany Hancock. The two of them had continued to correspond now for some three years about the burrowing powers of barnacles. Darwin had even written to Hancock a long and frustrated list of problems on Boxing Day of 1849, and here he was again with a similar set of questions covering several pages written on Christmas Day of 1852.33 This was the last sheer cliff face before the summit, and Hancock would be his fellow climber. He had set out all those years ago, he explained in his Christmas letter to Hancock, convinced, like Hancock, that Verruca had mechanical burrowing powers; it did its own digging somehow. But having found three other burrowing barnacles around the world, he had come to believe that burrowing barnacles made their dugouts through chemical action. He was the first to admit that this theory was still hypothetical. Now he must find evidence. The last entry in his journal for 1852 reads: ‘Began Verruca’.
Hancock was delighted to be a co-sailor on this last voyage of discovery, now that Darwin was going to attend to his creature, the barnacle he had discovered in 1849, the burrower Alcippe lampas, and particularly now that he had read and admired the second of the barnacle volumes. He wrote to express his admiration for the book and Darwin replied: ‘I am quite delighted at what you say about my little friends, the complemental males; I greatly feared that no one wd believe in them; & now I know that Owen, Dana & yourself are believers, I am most heartily content.’34
Other believers would be press-ganged on to the burrowing-barnacle ship, for he needed more burrowing specimens. Favours would have to be called in. Charles Spence Bate, the dentist who lived by the sea in Plymouth, was recruited to collect Verruca specimens from both calcareous and non-calcareous rocks so that Darwin could determine how they burrowed. Bate spent cold mornings at low tide down on the Devonshire beach scraping Verruca off different kinds of rocks, preserving them according to Darwin’s meticulous instructions and labelling them, all before he started a day’s work pulling teeth.
Only a week into the new year, Darwin’s spell of good health broke into bouts of flatulence and vomiting, perhaps exacerbated by the rich Christmas food. Now the grotesque and highly magnified body parts of Verruca, Alcippe, Arthrobalanus and Proteolepas coloured and streaked and twitched their way across Darwin’s dreams. When he closed his eyes, he could see them all in their puzzling nakedness, working to make a cavity for themselves. These were barnacles with the strangest anatomies of all – Alcippe was ‘one of the most difficult creatures’, he told Hancock, who had discovered it in 1849, and he simply did not know how to classify it. It was peculiar in almost every body part and, strangest of all, it had no rectum or anus, so that it had to ‘always eject … its excrement from its mouth’.35 When he wrote to Fox with news of the birth of Hooker’s first child, he couldn’t resist telling him about the vomiting, anus-less Alcippe: ‘I have this morning been dissecting a most abnormal cirripede, which after a good meal has to vomit forth the residuum, for there is no other exit! ‘I heard yesterday from Dr Hooker, who married Henslow’s eldest daughter, of the birth of a son under Chloroform, at Hitcham.’36
Embedded in the flesh of this vomiting female monster, with her vestige of a rudimentary and atrophied penis, were clusters of males so strange that he didn’t even recognize them as barnacles at first. Even now that he had seen the miraculous diversity that barnacles were capable of, he was still fooled by these, and had thrown the males away in the first dissections, thinking they were parasites of the Bryozoa; but looking again, he wrote to Hancock, he could see that these were more minute complemental males, like the Ibla males, living in the flesh of a large female, engorged with sperm:
The male is as transparent as glass… In the lower part we have an eye, & great testis & vesicula seminalis: in the capitulum we have nothing but a tremendously long penis coiled up & which can be exserted. There is no mouth no stomach no cirri, no proper thorax! The whole animal is reduced to an envelope (homologically consisting of 3 first segments of head) containing the testes, vesicula, & penis. In male Ibla, we have hardly any cirri or thorax; in some male Scalpellums no mouth; here both negatives are united… I believe the males occur on every female: in one case I found 12 males & two pupae on point of metamorphosis
permanently attached by cement to one female!37
When he had discovered the Ibla males, he had assumed them to be unique, but now he had found several examples of the emergence of separate sexes, all in different corners of the barnacle world. It was a rare adaptation but a singularly important one, for it helped to show further evidence for his developing ideas about sexual selection. When reproduction was essential for the survival of the species, having the longest penis in the animal kingdom was sometimes not enough. Supplementary males were an insurance strategy for less risky reproduction, by providing the species with a range of diverse reproductive methods.
January had been unusually warm but as February began, the barometer fell alarmingly and soon the country was beset by gales and snowstorms. Snow fell almost every day. George, now seven, took his ice-slide down to the frozen village pond to join his friends every morning and came back with his face flushed and hands blue. Emma had nursed William, Etty and George through an attack of mumps in early February, and by the beginning of March four-year-old Francis and five-year-old Lizzie had the tell-tale swollen faces and sore throats. William’s infection had delayed his return to school and he gratefully holed up in the warmth of the schoolroom with the copy of the Life of Napoleon Bonaparte, which his father loaned him. Emma helped him pack the book next to his ice-skates when the day came to return to school.38 There were icicles along the eaves and some of the late winter-ripening pears blushed pink and russet under thick white coats.
Darwin was delighted to have abandoned his daily douche back in August, for it would have been almost impossible to pump the water in this weather, let alone to tolerate icy water on naked flesh. The newspapers were full of accounts of accidents caused by exposure: three soldiers on Dartmoor had wandered into a snowdrift; the prisoners and guards of Dartmoor Prison had been virtually cut off from the rest of the world and were half-starved; railway tracks were blocked, and numerous ships had foundered in heavy gales.39 The weather conditions had produced other meteorological spectacles and dramas: sightings of the aurora borealis across England and Scotland and a mysterious fireball that had nearly destroyed Lincoln Cathedral on 23 February, hitting the tower and exploding in gale-force conditions and heavy snow. Three days later a hurricane hit the west coast and swept across the country, wrecking ships in the ports and out at sea, pulling off masts, rudders, anchors and sails. Hundreds of boats were driven ashore in thick snow.40