Darwin and the Barnacle

by Rebecca Stott

  Only weeks later, walking the hot, rocky beach of St Jago, a volcanic outcrop in the middle of the Atlantic, 450 miles from the coast of Africa, he found a small octopus marooned in a rock pool; but before he was able to reach it with his net, it darted into a crevice in the rock, leaving the water in the pool discoloured by a dark chestnut-brown ink. Darwin had learned patience hunting in the rock pools of Scotland. He could wait. He could be very still. Grandmother’s Footsteps. He watched the octopus emerge from its crevice as the water cleared again. But now he could hardly see it. Chameleon-like, it had changed its colour, disguising itself before his very eyes to match the colour of the rock-pool floor: French Grey with minute spots of yellow, disappearing and appearing by turns. Fascinated, rooted to the spot, he could not even reach for his net. Clouds of colour, Hyacinth Red and Chestnut Brown, continuously passed across its body. But were they like clouds or blushes? Darwin wondered, struggling with analogies. Putting these creatures into words taxed his vocabulary and his imagination.

  But who was hunting whom? As Darwin watched, the octopus remained ‘for a time motionless, it would then advance an inch or two, like a cat after a mouse, sometimes changing its colour’. Then it would dart away, ‘leaving a dusky train of ink to hide the hole into which it crawled’.11 Frustrated and amused, Darwin turned away, turning his back on his prey, wading further into the pools to look for other marine animals; but he was constantly distracted by the sound of grating behind him. The octopus he had abandoned was squirting water in his direction, aiming directly at him from its rock pool. Following the line of spray stealthily, keeping his head down, Darwin surprised his octopus playmate with his net and slipped it into his collecting jar. This animal had to be observed more closely. Back in the cabin that night, the ship at sea and Darwin sick again, the chameleon octopus glowed angrily in the dark, the only light in the pitch-black cabin. It did not live long. Darwin was too sick to either release it or label it. ‘Here I have spent three days in painful indolence, whilst animals are staring me in the face, without labels or epitaphs,’ he complained on 12 February 1832.12

  Grant’s zoophytes and swimming eggs still haunted him here right from the start of the voyage. Becalmed off Tenerife, he had seen the sea lit up by zoophytes much too small to see. This was an opportunity not to be missed, an opportunity to study the body structures of these luminous borderline creatures. The plankton net he had made modelled on Coldstream’s diagram of an oyster dredger from the Firth of Forth worked well: ‘I proved today the utility of a contrivance which will afford me many hours of amusement & work – it is a bag four feet deep, made of bunting, & attached to [a] semicircular bow this by lines is kept upright, & dragged behind the vessel – this evening it brought up a mass of small animals, & tomorrow I look forward to a greater harvest.’13

  Many of the books he had consulted with Robert Grant and John Coldstream were in the ship’s cabin – expensive, leather-bound books on marine invertebrates by Lamouroux, Cuvier, Lamarck, Thompson and Fleming, most purchased from Treuttel, Wurtz and Richter, a specialist bookshop at 30 Soho Square, London.14 Sometimes he would write guiltily home to his sisters to ask them to buy new books from Treuttel’s and post them out to him: ‘When you read this I am afraid that you will think that I am like the Midshipman in Persuasion who never wrote home, excepting when he wanted to beg: it is chiefly for more books; those most valuable of all valuable things …’15 But there were many species he found that were still unmapped, even in the newest zoology books they sent.

  The first day he used his plankton net, it brought in a jellyfish and Portuguese man-of-war, Physalia physalis. The man-of-war looks like a jellyfish, but its jelly-like pale-purple translucent float has a comb of pleats along the top like a Mohican haircut. This sea punk uses its raised crest like a sail to catch the wind. Beneath the surface of the water, its trailing tentacles, some tens of metres long, look like chains of coiled purple jewels. But this is no man-of-war; it is a veritable army, a colony of highly poisonous polyps, dependent upon one another for survival. Under the float one community of polyps breeds and dies, while the deadly tentacles of others catch and paralyse small fish. Another group of polyps seizes this food and spreads over it to digest it – one body, one colony of bodies, hunting, breeding, being born, digesting, dying. Where does life begin and end here? Where does an individual begin and end?

  Darwin, excited, tried to tease out the pale purple tentacles caught up in the dredging net: ‘getting some slime on my finger from the filaments it gave considerable pain, & by accident putting my finger into my mouth I experienced the sensation that biting the root of the Arum produces.’16 Perhaps only the obsessively curious Darwin could have made such a comparison. Had he experimented with the arum root too in the gardens at Shrewbury as a small boy? Knowing it to be poisonous, had he dug up the potato-like root and bitten into it, just to be sure? Just to feel the painful sting on his tongue. Just to know.

  6 Darwin’s Colour Chart

  The colours of the sea creatures, like the gorgeous purples and pinks of the man-of-war, amazed him. They seemed to get more vivid and gaudy as the ship sailed further south.17 By February and March he was struggling for words to describe the colours of the marine creatures he was cataloguing daily. One of his zoological friends had insisted that he take the geologist Abraham Gottlob Werner’s colour charts with him, usefully edited into a book by the Edinburgh miniaturist Patrick Syme.18 The colour charts enabled scientists to match the colour of a cuttlefish tentacle or piece of granite or butterfly wing to a named colour that could be consulted by other naturalists. To indicate that he was using Werner’s colour chart names, Darwin capitalized them in his descriptions: Lake Red. Ink Black. China Blue. Saffron Yellow. Peach Blossom and Aurora Red. Pistachio Green. Oil Green. Wood Brown – colours to taste, smell and touch; colours in poetry, colours spanning the vegetable mineral, and animal kingdoms:

  Shimmed Milk White White of human eyeballs Back of the petals of Blue Hepatica Common Opal

  Wine Yellow Body of the Silk Moth White Currants Saxon Topaz

  Flesh Red Human Skin Larks Spur Heavy Spar Limestone

  It was overwhelming. These tropical seas yielded sensual pleasures beyond his imaginings – beyond even the treasures of Prestonpans. Sitting amongst the rock pools on the western rocky shore of Quail Island in the Atlantic, eating ripe tamarinds and biscuits towards the end of January, Darwin remembered the sands of Leith:

  Often whilst at Edinburgh, have I gazed at the pools of water left by the tide; & from the minute corals of our own shore pictured to myself those of larger growth: little did I think how exquisite their beauty is & still less did I expect my hopes of seeing them would ever be realised. – And in what a manner has it come to pass, never in the wildest castles in the air did I imagine so good a plan; it was beyond the bounds of the little reason that such day-dreams require. – After having selected a series of geolog, specimens & collected numerous animals from the sea, – I sat myself down to a luncheon of ripe tamarinds & biscuit; the day was hot, but not much more than the summers of England.19

  Would people believe his accounts of these bizarre and gaudy creatures? he wondered. They would sound so fantastic. He wrote to Henslow later that year: ‘After this I had better be silent – for you will think me a Baron Münchausen amongst Naturalists.’20

  In 1785 a jewel thief from Hanover named Rudolf Erich Raspe published a satirical book in England, The Adventures of Baron Münchausen, which claimed to be based on the life and travels of a notorious Baron Münchausen, who had a reputation for embellishing his war stories. The book included, for instance, the Baron’s ‘Extraordinary flight on the back of an eagle, over France to Gibraltar, South and North America, the Polar Regions, and back to England, within six-and-thirty hours’ and told of the time the baron tethered his horse to a ‘small twig’ in a snowstorm, and discovered when the snow melted that the twig was actually a church steeple. Were Darwin’s theories castles in the air like the
Baron’s? His imagination didn’t torment him as Coldstream’s had – his only problem was how to prove such castles in the air, how to bring them into the realm of plausibility. That’s what all the scratching and recording and collecting of evidence was for.

  7 Botofogo Bay

  The heat was so extreme as the ship sailed towards Rio de Janeiro in February 1832 that Darwin slept naked on the mahogany dissecting table at night. Even then he complained that he felt as if he were being stewed in warmed melted butter.21

  Back in Leith the winter weather was not so balmy. John Coldstream, the doctor who still walked Leith sands in the early morning with his glass jars and nets, was also preparing for the cholera epidemic that was moving north, driven by the as-yet-unknown water-borne cholera bacillus. The disease had already killed 6,000 people in London. Most people who died did so in less than twenty-four hours, from dehydration caused by chronic diarrhoea. Coldstream and the other Leith medical men could do nothing but wait, order the medications from London and prepare a hospital for the sick. On Sunday, 22 January 1832, Coldstream wrote in his journal: ‘The cholera is now within four miles of us and we are hourly expecting it at Leith.’22 But, although cases were multiplying fast in the seaside village of Musselburgh, four miles away, the disease didn’t arrive in Leith until the end of February. Coldstream knew that this was the beginning of chaos. On 29 February he wrote:

  How various is the lot of men! Tonight all is quiet around roe. I have no patients very seriously ill; all our family are well and happy; the town is peaceful and still, while only four miles off, pestilence prevails; men die by twenties and thirties a-day – all classes are panic-struck, and the medical men are labouring in their vocation by night and by day. How soon the aspect of things may be changed here, God only knows.23

  Darwin’s sister Susan wrote to him anxiously about cholera in Shrewsbury; there were already twenty cases in Darwin’s home town by August 1832.24 But it was the rapidly expanding industrial cities where cholera had taken its most secure hold, cities in which overcrowding and unsanitary conditions provided an ideal environment for the survival and propagation of the cholera bacterium but not for the survival of the urban poor. Britain’s population had doubled in thirty years. The cholera pamphlets, many written by doctors for the middle classes, warned about the dangers and pestilence of the slums. Some even argued that the centres of the disease, so often the poorest areas of the town, such as the port areas of Leith, should be sealed off and policed. The middle classes flocked to seaside resorts in the hope that the sea air would dispel the supposedly airborne germs, not understanding that it was the water they drank that poisoned them. By September of that year, Coldstream, working night and day in Leith hospital since January, was suffering from chronic exhaustion. When his doctor ordered a seaside convalescence, he took lodgings in Torquay with two of his sisters and a cousin and devoted himself to a winter of marine zoology.

  Cholera was sweeping across Ireland, too, as Darwin sailed ever closer to the shores of South America in 1832. In Cork an ex-army surgeon, William Vaughan Thompson, who had been promoted to the position of Inspector General of Cork Hospital, had just published a book called Cholera Unmasked. However, back in Britain it wasn’t this doctor’s work on cholera that people were talking about, but his work on barnacles, crustacea, and phosphorescent sea creatures, a book published in 1830 as Zoological Researches and Illustrations; Or a Natural History of Nondescript or Imperfectly Known Animals. This series of memoirs, based on painstaking microscopal observations, made him the talk of the zoological societies in London. Linnaeus and Cuvier had defined barnacles as molluscs through a lack of understanding of their metamorphosis and of their internal anatomy. Thompson had watched these metamorphoses through long hours at his powerful new microscope and proved that, like insects, they metamorphosed in extraordinary ways. He had seen free-swimming barnacles shape-shift into adult barnacles that glued themselves to rocks.

  The philosophical implications of Thompson’s discoveries were unlimited. If barnacles and crabs had been seriously misunderstood by Linnaeus, Cuvier and even Lamarck, he implied, every marine invertebrate had to be rethought. Dramatic body changes like these were supposed to be common only amongst insects. What kind of mirroring was this? Land and sea: patterns above and below the water. Thompson was a zoology detective working like Grant with patience, a powerful microscope and a watch glass. He might have called his zoology book Barnacles Unmasked, but, unlike Grant, he wasn’t interested in the philosophical implications of his discoveries. He was satisfied to have discovered these underwater metamorphoses and to argue for reclassification. Barnacles were simply in the wrong boxes and needed to be moved to the right boxes, restored to their proper God-given family. Others, however, would use his amassed facts and observations for philosophical ends.

  Thompson, like Darwin who ordered a copy of this ground-breaking book for the Beagle library before it sailed, was enthralled by the poetry of marine life forms. He was no dry systematist. He had sailed the world as a ship’s doctor and, apart from the extraordinary descriptions of the metamorphosis of barnacles, his book was full of engaging accounts of phosphorescent tropical seas such as those Darwin had seen off the coast of Tenerife:

  Returning from a fishing party late in a still evening across the bay of Gibraltar, in a direction from the Pomones river to the old Mole, in company with Dr Drummond (now Professor of Anatomy to the Belfast institution) and a party of naval officers, the several boats, though separated a considerable distance, could be distinctly traced though the gloom by the snowy whiteness of their course, while that in which we were, seemed to be passing through a sea of melted silver; such at least was the appearance of the water, displaced by the movement of the boat and the motion of the oars, the hand, a stick, or the end of a rope, immersed in the water, instantly became luminous and all their parts visible, and when withdrawn, brought up numerous luminous points less than the smallest pin’s-head, and of the softest and most destructible tenderness.25

  Darwin, too, continued to see swarms of phosphorescent zoophytes, no bigger than a pin’s head, lighting up the surface of the sea like glow-worms, wherever they sailed. On route to Buenos Aires in October 1832:

  The night was pitch dark with a fresh breeze. – The sea from its extreme luminousness presented a wonderful & most beautiful appearance; every part of the water, which by day is seen with foam, glowed with a pale light. The vessel drove before her bows two billows of liquid phosphorus, and in her wake she was followed by a milky train. – As far as the eye reached, the crest of every wave was bright; & from the reflected light, the sky just above the horizon was so utterly dark as the rest of the heavens. – it was impossible to behold this plain of matter, as it were melting and consuming by heat, without being reminded of Milton’s description of the regions of Chaos and Anarchy.26

  Under the microscope these phosphorescent ‘lower’ creatures were beautiful and strange, he wrote: ‘Many of these creatures so low in the scale of nature are most exquisite in their forms & rich colours. – It creates a feeling of wonder that so much beauty should be apparently created for such little purposed.’27

  So much beauty for so little purpose. Unlike John Vaughan Thompson, Darwin did not try to frame his discoveries in terms of a revelation of God’s benevolent purpose. Thompson really believed that the zoophytes’ purpose, the reason they had been put on the earth, was to light up the ocean at night so that sailors would be able to avoid shipwreck. ‘The object of the Creator is not always obvious,’ he concluded.28 Though Darwin was not a deist like his father and grandfather, he had learned from them the habit of separating his religious belief from his scientific enquiry. It wasn’t that he didn’t feel a divine presence in nature in – the vast beauty of a tropical forest or under a starlit sky – but that framing all the questions that dogged him in terms of the purpose of a divine creator just was not a habit of mind. When he found Thompson searching for these explanations above all other pos
sible explanations, it surprised him. What was interesting to him now was precisely the apparent lack of purpose of the zoophytes’ nocturnal lights. Was it a signal to attract the opposite zoophyte sex? It couldn’t be, because most zoophytes were hermaphrodite. The beauty, Darwin was sure, was simply a by-product of nature’s processes: the phosphorescence, he believed, was caused by decomposing bodies of millions of dead zoophytes amongst the live ones, a process by which the ocean purified itself – like breathing out toxins. It was purpose enough; and poetry enough.

  Elsewhere, other swarms of infusoria or confervae, filaments of microscopic plants, made the surface of the sea look red or muddy brown. Off the coast of Chile, Mr Sulivan brought Darwin a watch glass filled with seawater stained a pale red. He had already taken a look at the water under his own microscope and had seen, he said, ‘moving points’. They took turns looking through the lens of Darwin’s stronger microscope. Darwin saw thousands of oval shapes, contracted with a hairy ring around their middle, hairs that the organisms were using to propel themselves through the water. The instant they stopped moving their bodies burst. Simply exploded, ejecting coarse brown granular matter into the water.29 South of Bahia, in September 1832, the whole surface of the sea was discoloured with bands of mud-coloured water, sometimes miles long. Under the microscope these confervae looked like chopped bits of hay. With a stronger lens Darwin could see that each part was made up of bundles of between twenty and sixty cylinders, and sacks filled with granular matter.