Darwin's Ghosts

by Rebecca Stott

  As soon as the new jars of aquatic creatures arrived in Paris, Réaumur repeated the experiments following Trembley’s detailed instructions—cutting and waiting and watching through the microscope. The creature—Réaumur named it a polyp, meaning “many armed”—regenerated itself again and again. Exhilarated by the philosophical questions the experiment raised, questions already being discussed heatedly in salons and coffeehouses across Paris, Réaumur repeated the demonstration over the three following days both to the “entire academy” and “to the court and the city” in Paris. The microscopic polyp had become a circus animal.

  Back in The Hague, Trembley and his young protégés spent the spring of 1741 developing more experiments for their pond polyps. They learned to produce a polyp with seven heads, provoked a polyp to “swallow” other polyps, grafted the halves of two different polyps together, and turned one inside out. Trembley had scores of experiments planned. He wanted to learn everything knowable and measurable about his “little machine.”

  In April 1741, Bonnet, already struggling with strained eyes, began a new series of aphid experiments in order to answer Trembley’s question about how many generations of aphids might be produced without coupling. This time he watched through night and day for three months as nine generations of aphids emerged. When he had asked Trembley to solve the aphid enigma, his friend had made a valiant effort and then, defeated, had asked “Who knows?” in his letter of reply. “If this excellent friend had been able to foresee all the evil that his ‘who knows’ did to my eyes,” Bonnet wrote, “I am very sure that his tender friendship for me would not have permitted him to express it. It was, however, on this simple ‘who knows’ that I undertook a new study which was much more laborious than the preceding one. I was young and full of ardour: it seemed that these two words reduced to nothing all my previous work.”

  By the end of the summer, the polyp had usurped the place of the aphid as the philosophical object of the season in Paris. In August, Réaumur wrote to Trembley to report that in Paris, “never did an insect cause so much uproar as do the polyps.” The reports of the Academy of Sciences for 1741 described the discovery in sensational theatrical language: “The story of the Phoenix who is born from the ashes as fabulous as it might be, offers nothing more marvellous.… From each portion of the same animal cut in 2, 3, 4, 10, 20, 30, 40 parts, and, so to speak, chopped up, just as many complete animals are reborn, similar to the first. Each of these is ready to undergo the same division … without it being known yet at what point this astonishing multiplication will cease.” The popular French entomologist Gilles Bazin described the upset in his novel Letters from Eugène to Clarice on the Subject of the Animals Called Polypes (Lettres d’Eugène à Clarice): “A miserable insect has just shown itself to the world and has changed what up to now we have believed to be the immutable order of nature. The philosophers have been frightened; a poet told us that death itself has grown pale.”

  But Réaumur also wrote to tell Trembley that he was encountering skepticism everywhere among the natural philosophers of Europe. Everyone who had not seen the polyp regenerating with his or her own eyes remained an incrédule, he reported—an unbeliever.

  More of a philosopher than his uncle, Charles Bonnet was quickly alarmed by the potential metaphysical meanings of the polyp experiments. What did it all mean? If this simple creature could be cut up into infinite parts and regenerate itself from these parts, then where was its soul? Was Descartes then right after all to argue that the universe and all living organisms were like clocks governed by natural laws? Like many Christian natural philosophers in the seventeenth and eighteenth centuries, Bonnet was always looking for opportunities to refute this apparently reductionist and potentially godless way of seeing the world. Every time he admired a complex organism or looked at the patterns on the wing feathers of a bird under the microscope, it was for him further evidence of the miracle and benevolence of God’s design. But the design was looking increasingly incomprehensible. Under the microscope, nature was looking more and more various, bizarre, and wayward. Its codes were becoming indecipherable.

  Increasingly aware that Trembley’s polyp was being taken up by materialists (there is only matter—there is no supernatural controlling force) and atheists (there is no God), Charles Bonnet, now three months into his aphid vigil and a little high-strung, wrote to his professor Gabriel Cramer in Geneva in June: “All that I ardently wish is that my poor insects will not be degraded too much, and I have reason to fear it terribly. I beg you, Sir, strive not to let [the insects] become simple machines. I will be inconsolable.… Good-bye then to all industry, all skills, all kinds of intelligence. And if you cannot get them out of this difficulty who can?” Professor Cramer reminded him that, though the polyps did seem “to deal a heavy blow to the System of soul in animals,” it was simply too early to draw conclusions. “Let me breathe a little,” he replied. “You are overwhelming us with marvels.”

  In the summer of 1741, Bonnet, his sight increasingly blurred, began to look for other regenerating animals. Unable to find polyps in the ponds around Geneva, he began to experiment on aquatic worms. Extraordinarily, he discovered that they, too, reproduced themselves when cut in half. Réaumur, who was delighted by Bonnet’s findings, urged him to look further. How far does this pattern extend in nature? What about sea nettles and starfish? he asked. If you cut them, will they regenerate? Within months Bonnet produced a worm with a tail where its head should be. It was too much for the young naturalist, who was still only twenty-one. He needed clear theological explanations.

  The professors at Geneva were also confounded. In November 1741, Bonnet wrote to Réaumur himself asking him why God had given such miraculous regenerative powers to insects and not to his greatest work, Man. “For what end?” he asked. Réaumur did not know how to answer. He proposed a bland explanation: perhaps God had given animals that were designed as mass food for other animals the ability to reproduce the part that had not been eaten. Bonnet was not satisfied.

  Abraham Trembley was not concerned with metaphysics; he wanted only to make the polyp regeneration visible to as many people as possible. If European philosophers were not prepared to believe the word of a low-born Genevan tutor living in Holland or to accept the endorsements of the members of the Academy of Sciences, he told the Bentinck boys, more people must see the experiments with their own eyes. The polyps must speak for themselves. Trembley began sending out packets of live polyps in glass jars by mail to addresses across Europe—universities, academies, salons—with meticulous instructions on how to undertake the experiments. Two years later he had 140 jars in his study, complaining in July 1743: “I am entirely taken up with dispatching polyps to one place or another.”

  Using the postal system, Trembley began to create witnesses in every city in Europe. It was a brilliant strategy at a time when all natural philosophers, influenced by the writings of Francis Bacon, stressed empirical observation and experimentation above speculation. Despite the disruptions to the postal networks caused by the War of the Austrian Succession,* the polyp experiments were performed and repeated like circus shows in public in Rome, Siena, and Germany; in Sweden in 1746, Abraham Beeck wrote, “Apart from electricity, naturalists did not deal with anything this year other than the polyp.” Each one of those witnesses was part of a network of speculation and talk and correspondence across many different languages; each of those networks was part of a larger one. Everywhere the polyps converted the incrédules. Ambassadors carried news of them from court to court. Everywhere the philosophical talk spread.

  British naturalists, however, remained resolutely skeptical; they quickly turned the polyp into a joke. Although the famous French naturalist Georges-Louis Leclerc de Buffon wrote to the president of the Royal Society in Britain, Martin Folkes, about the polyp experiments as early as 1741, and William Bentinck’s brother Charles and Jan Frederick Gronovius had published excited reports in the journal Philosophical Transactions of the Royal Societ
y, Folkes doubted Trembley’s credentials and wrote to William Bentinck, Trembley’s employer, for verification. Trembley was, after all, only a tutor, working with two young boys as his witnesses. Intrigued, Folkes also wrote to the famous French salonnière Madame Geoffrin for her assessment of the polyp talk in Paris. She gave him a long report by letter describing the experiments she had seen at Professor Réaumur’s house that summer; philosophical opinion was divided among the Parisian savants, she told him, but she could certainly confirm that the polyp was preoccupying the finest minds in Paris.

  Finally, in March 1743, at Folkes’s invitation, Trembley dispatched a container of polyps to England. It arrived the following day. Folkes invited twenty fellows of the Royal Society to his home to witness the experiments. The polyps regenerated within hours. On March 17, he repeated the experiments at a meeting of the Royal Society, where in the course of a week more than 150 people saw them. It took Folkes some time to apologize to Trembley, but when he did so, he did it gracefully: “We are no less sensible of your great candour, and the Readiness you have shown not only to transmit to us faithful abstracts of your own experiments,” he wrote, “but also to send us the Insects themselves, whereby we have been enabled to examine by our selves, and see with our own Eyes the Truth of the astonishing Facts, you had before made us acquainted with.”

  One of the witnesses in Folkes’s house in March 1743 was the journalist, poet, and naturalist Henry Baker, son-in-law of Daniel Defoe and author of The Microscope Made Easy. Fascinated by what he had seen, he persuaded Folkes to give him three of the polyps and to lend him Trembley’s letters. All through April he cut and multiplied the polyps in his London house until he had hundreds; he watched them under his microscopes; he sent out corked jars full of live specimens to everyone he could think of in Oxford and Cambridge. Friends brought him English polyps from the ponds of Hackney and Essex. As the spring came and the air warmed, the polyps, both Dutch and British, multiplied even faster as they fed on small worms that Baker had his servants dig out of the black mud of the Thames. Determined to publicize the discovery and frustrated that nothing was yet in print, Baker published a two-hundred-page account of his repetitions of Trembley’s experiments with woodcut illustrations as An Attempt Towards a Natural History of the Polype in November 1743 before Trembley had published his own memoir. The polyp’s regenerating skills were extraordinary, he wrote, but no one should waste any time on philosophical speculation. Any such hypothesizing, he told his readers, would be “a kind of Madness,” a “Cobweb of the Brain.”

  British naturalists were now enthralled, the editor of the French journal Library of Britain (Bibliothèque Britannique) reported in the autumn of 1743: “The marvelous properties of the new Polyp … have become the object of such a curiosity and research of some of the members of the Royal Society, that Mr. Cromwell Mortimer, Secretary of this illustrious assembly, has but given in the no. 467 of the Transactions pieces which only relate to it.” But although the polyp story had appeared in print in reports of the various scientific societies and in letters, in Baker’s book, and finally in Abraham Trembley’s long-awaited memoir, published in Leiden in 1744 and immediately pirated by a Parisian publisher, it largely traveled by word of mouth. In salons from Paris to Leiden to Oslo to Rome and Siena, the polyp, silently miraculous, was the subject of long, animated conversations. It had become a sensation.

  Literary satirists immediately plunged in. Henry Fielding published a satirical pamphlet on the self-generating powers of money called “Chrusippus, Gold-foot or Guinea” in 1743; in 1751 the Scottish poet Tobias George Smollett, contemptuous of any philosophical subject that had no economic use, vented his spleen in Peregrine Pickle at the “muck-worm philosophers” who counted angels on a pinhead; in 1752 Vincent Miller published Man-Plant, or a Scheme for Increasing and Improving the British Breed. Within months of the Royal Society experiments of 1743, Charles Hanbury Williams satirized the philosophical pretensions of the aristocracy in a narrative poem called “Isabella, or the Morning.” “Pray, Mr. Stanhope, what’s the news in town?” the duchess asks her visitor.

  “Madam, I know of none; but I’m just come

  From seeing a curiosity at home:

  ’Twas sent to Martin Folkes, as being rare,

  And he and Desaguliers brought it there:

  It’s call’d a Polypus.”—“What’s that?”—“A creature,

  The wonderful’st of all the works of nature:

  Hither it came from Holland, where ’twas caught

  (I should not say it came, for it was brought);

  To-morrow we’re to have it at Crane-court,

  And ’tis a reptile of so strange a sort,

  That if ’tis cut in two, it is not dead;

  Its head shoots out a tail, its tail a head;

  Take out its middle, and observe its ends,

  Here a head rises, there a tail descends;

  Or cut off any part that you desire,

  That part extends, and makes itself entire:

  But what it feeds on still remains a doubt,

  Or how it generates, is not found out:

  But at our Board, to-morrow, ’twill appear,

  And then ’twill be consider’d and made clear,

  For all the learned body will be there.”

  “Lord, I must see it, or I’m undone,”

  The Duchess cry’d, “pray can’t you get me one?

  I never heard of such a thing before,

  I long to cut it and make fifty more;

  I’d have a cage made up in taste for mine,

  And, Dicky—you shall give me a design.”

  But what did it all mean? How would Dicky have explained the philosophical implications to the duchess if she had asked? Trembley himself, influenced by his mentor Réaumur’s warnings against rash philosophizing, held back on offering meanings or philosophical interpretation. His memoir contains no philosophical conjecture, no theory, just detailed facts and descriptions of the hundreds of experiments he had made.

  Bonnet, on the other hand, continued to find himself entangled in this philosophical “Cobweb of the Brain.” All through the 1750s, as his eyesight weakened, he wrestled with the perplexing questions the polyp presented. Finally, late in that decade, he came to a position that seemed to reconcile all the polyp- and aphid-generated metaphysics that kept him awake at night and disturbed his religious beliefs. The polyp appeared to be the point of passage between the animal and vegetable kingdoms, which suggested either that the borders were permeable or that they did not exist at all. You could cut the polyp a hundred times and it would regenerate from the smallest part. An aphid could reproduce without sex. The answer was simple: God had originally created a multitude of germs on a graduated scale, each with the power of self-development. Over enormous lengths of time, the germs modified and improved. If there was progress, he argued, it took place within the species. Species boundaries were inviolable and designed by God. They were fixed. “Nature is assuredly admirable in the conservation of individuals,” he wrote, “but she is especially so in the conservation of species.… No changes, no alteration, perfect identity. Species maintain themselves vigorously over the elements, over time, over death, and the term of their duration is unknown.” The regeneration of the polyp proved not that there was no God but that species were indestructible, immortal. Man was immortal.

  Trembley was shocked and surprised by his nephew’s speculative claims about his polyps; close observation of nature and not philosophical speculation had been the object of his work. But it was too late. Now that the polyps’ regenerating abilities had been witnessed by hundreds across Europe, their meanings were out of his hands. He wrote to his employer William Bentinck in January 1750 complaining that naturalists everywhere were being too quick to jump to metaphysical conclusions, including the great Comte de Buffon in his newly published first volume of Natural History (Histoire naturelle, générale et particulière): “Mr. de Buffon claims to explain near
ly everything about generation, but I admit that I can only consider his system as a dangerous hypothesis. He tries to prove too much with the facts on which it is built. He seems to let himself be carried away by the imagination. If his work is very popular, I am afraid that he will do harm to Natural History by bringing back the taste for hypotheses.”

  Now that so many men and women had seen the polyp regenerate, the European imagination could not be so easily reined in. In Paris and London, Berlin and Rome, microscope and microscope guidebook sales increased dramatically; across the world, intellectuals installed experimental apparatus in their studies; naturalists turned away from their botanical or beetle collections and instead scoured ponds and rock pools searching for more incomprehensible tentacled and budding creatures or peered down the eyeglasses of ever more powerful microscopes to watch the looping, oozing, and spawning of corals or infusoria. Ponds, seabeds, and rock pools, naturalists declared, were terra incognita teeming with minute, incomprehensible, inconceivable bodies that would expand the range of nature’s laws beyond anything previously believed possible. For those inclined, like Charles Bonnet, to ponder, the polyp profoundly challenged contemporary beliefs in intelligent design: If man had dominion, if he was valued by God above all other creatures, why had he not been granted powers of regeneration like the polyp? If nature was really arranged on a scale with man at its pinnacle, why had such a simple creature been granted such complexity? And if nature’s workings included laws as bizarre as animal regeneration, what other laws might yet be discovered?