The motto makes Harvey sound more modern than he was. He didn’t mean that the egg was the female’s contribution to the new life she helped create, the counterpart of the male’s semen. The heart of his claim was that humans and all other mammals begin their lives as fragile clumps of tissue, as tiny, naked eggs that grow within the mother’s body. (Harvey and his contemporaries jumbled together different senses of the word “egg” in a way that confused them and still confuses modern readers. When we talk about a woman’s eggs today, we have in mind the sex cells that unite with sperm cells to form embryos. Harvey did not know about sex cells. For him, “egg” meant “tiny embryo.” In addition to that conceptual and linguistic muddle, Harvey had made a significant anatomical mistake: he discounted the role of the ovaries and believed that eggs originated in the uterus.)
Just what the woman’s contribution to pregnancy was, Harvey admitted, he had not managed to learn. And his analogies—conception was like infection or magnetism or thought—did “but replace one mystery by another.” As frank as ever, he spelled out his failure in plain language. “There is no sensible [i.e., detectable] thing to be found in the uterus, after coition,” he wrote in exasperation, “and yet there is a necessity that something should be there.” He bristled for a moment—no one else had come close to finding an answer “even in his dreams”—but then he conceded that he had not, either. He had no choice “but to confess myself at a standstill.”
But in several ways Harvey had moved the case decisively along. So widely admired was he by this time, for starters, that he had shifted the debate. By focusing so intently on the egg—even though his notion of the egg was hazy—he had in effect directed the next generation of scientists to find those eggs at all costs.
Next, Harvey had ended the reign of his hero, Aristotle. Whatever would eventually turn out to be true, the semen-and-menstrual-blood theory was false. In the detectives’ case room, the picture of Aristotle now bore a large X.
Harvey’s last lesson was the most important. The way to take on this mystery was to stop talking and start experimenting.
EIGHT
SHARKS’ TEETH AND COWS’ EGGS
ON JULY 15, 1669, JUST A DECADE AFTER HARVEY’S DEATH, AN unlikely package arrived at the headquarters of the Royal Society, in London. Inside a small glass jar was a tangled snarl of skinny, floppy tubes floating in a clear liquid, like a miniature pasta dish gone awry. A proud note resolved the mystery of the jar’s contents. The Royal Society had before it, according to one Regnier de Graaf, “the testicle of a dormouse, unraveled by my method.”
This dormouse preparation sounds like a spoof of an unlikely venture, as if someone had gathered shavings from a unicorn’s horn. In truth it resolved a basic question in anatomy, and it showed how skilled de Graaf was in sorting out such riddles. A young, self-assured Dutchman—he was only twenty-eight when he sent his gift to the Royal Society—de Graaf was a physician with a special interest in anatomy and the mysteries of reproduction. Born when Harvey was already an old man, de Graaf and a handful of rivals would claim the next era in the sex and reproduction story for themselves.
Harvey had guessed right about the crucial importance of eggs, but he had not proved his case. That giant task still lay ahead. Still unresolved, too, were a host of fundamental questions concerning sexual anatomy. Taking on those mysteries would be the mission of de Graaf and his frenemies. They would grab the baton from Harvey and race ahead, happily opening up new territory at one moment, knocking off old riddles at the next, and mocking their foolish peers in between times.
A handsome, square-jawed, outgoing man, de Graaf subverted the cliché of the shy and awkward scholar. Despite a starry record in his university days, he never held an academic post, presumably because of the prejudice he faced as a Catholic in Protestant Holland. Instead, he practiced medicine in Delft. His practice thrived, but he truly came alive only when he had sent off his last patient of the day. Then he turned to his own research.
Until de Graaf took up the dormouse, no one had truly understood the structure of testicles. Were they some sort of solid, bean-like gland? The answer, de Graaf demonstrated, was that the testicles were made up of countless, tangled tubules. Take those tubules from a dog, say, and try to disentangle them, and the result was a hideous mess.
But try the same experiment with a dormouse,* and “you will behold a delightful and surprising sight.” Put the tubules in a pan of water, and they separated and unraveled by themselves. “I often demonstrated this to the physicians and surgeons of this city,” de Graaf boasted. His audiences gossiped so excitedly about what he had showed them, he went on, that “I became afraid lest, because of the laziness of the engraver, another should snatch from me the glory of this magnificent discovery” before he’d had a chance to publish it himself.
De Graaf set out his anatomical discoveries in two volumes, one on males and one on females. Both were clear and down-to-earth, especially in contrast with Harvey’s sometimes obscure prose. “Whatever is procreated of the semen properly so called originates and is perfected either in the same place or in different places,” Harvey wrote, in one typically dense passage. De Graaf was not as arcane. The male genitals consist of “the part that enters the vagina, and the one which remains outside hanging down like a bag.”*
FIGURE 8.1. De Graaf’s “magnificent discovery”: the structure of a dormouse testicle revealed.
That plainspoken tone was characteristic. “The pleasure of copulation is indescribable,” de Graaf remarked, and taking his own advice, he moved on at once to other matters. He was similarly brisk when considering time-honored but “absurd” doctrines, like Hippocrates’s claim that sperm from the right testicle produced males and, from the left, females. De Graaf told of “a citizen of Delft who possessed only a right testicle and yet was presented with various daughters by a most honorable wife.”
He had just as little time for Aristotle’s claim that the testicles served only as counterweights to keep the sperm ducts untangled. De Graaf had seen illnesses and injuries to the testicles that rendered men sterile; those men still had counterweights, but they could not father children. And what of birds and other animals whose testicles were inside their abdomen? In that position, they “could not possibly act as weights,” and yet the animals reproduced perfectly well.
Combative and sarcastic, de Graaf flailed energetically at his enemies. “I am certainly surprised that men of outstanding ability can still be mistaken in such an obvious matter,” or, more bluntly, “Your book came out of your arse, not your head.” At times he snarled in exasperation. “Certain people want to know how semen, which has its origin from such very red blood, grows milky white.” Who had time for such questions? “This should no more cause surprise than the fact that milk is white, although it draws its origin from green plants.”
Even worse than critics were poachers who ventured too near de Graaf’s own discoveries. He had sent his dormouse to the Royal Society in the first place because he had heard the “astonishing” news that English scientists claimed they had found the structure of the testicles before he had. They had done no such thing. Their accounts of their supposed discoveries had to be “twisted like a waxen nose” before anyone could find any sense at all in what they had said. Compare their vague words with the magnificent contents of this bell jar!
THE REASON FOR THE RANCOR WAS COMPETITION. THE SEX MYSTERY was in the air, and someone was going to make his name. De Graaf had many rivals; two of the most accomplished were slightly older contemporaries he had come to know at Leiden University in Holland. Both were destined to make major contributions to science, to abandon science at the peak of their careers so that they could devote themselves fully to God, and to die young.
Nicolaus Steno was Danish, a physician by training but a man of such varied and shifting interests that he pleaded with God for steadfastness. “I pray thee, O God, take this plague from me and free my soul of all distraction, to work on one thing a
lone,” he wrote in his journal. God paid no heed. Medicine’s main rival for Steno’s attention was geology. He was the first to explain why fossilized seashells turn up on mountaintops, and he showed that the Earth is ancient (though he never said outright that the customary Bible-derived age of a mere six thousand years could not be correct). He pursued medicine and geology almost simultaneously, dashing between investigations. His skill in dissection was so formidable that one dazzled spectator, who had watched him tease apart the eye of a horse, exclaimed, “He would count the bones of a flea—if fleas have bones.”
In 1666 Steno’s various interests converged. A fishing boat off the Italian coast hauled in a great white shark. Steno, who was twenty-eight at the time, was working at the Medici palace in Florence, where the grand duke supported a kind of informal scientific academy. So fascinating a trophy surely had to be investigated in Florence. There Steno dissected the head of the 2,600-pound monster.
He focused primarily on the great beast’s teeth. They bore a striking resemblance to well-known, reputedly magical stones called “tongue stones.” Folk wisdom had it that the stones fell from the sky on moonless nights (which explained why no one had ever seen it happen). Steno had no time for old myths. He held a shark tooth and a tongue stone next to one another and showed that they resembled one another as closely “as one egg resembles another.” Tongue stones, Steno explained, were fossilized shark teeth.
More important, Steno explained how it could be that a farmer plowing a field miles from the ocean might unearth signs of life from an ancient sea. The earth was restless, Steno wrote. Wait long enough, and seas might rise up and mountains tumble down.
Steno wrote up his findings for the grand duke and included them as a sort of afterword to a longer work on the anatomy of muscles. Almost as an afterthought, he added still another few pages. This section, too, veered away from what had come before, though Steno did discuss sharks once more. This time he focused on reproductive anatomy, based on his dissections of a different species of shark, the dogfish, and also of stingrays.
Sharks give birth to live young, and rays lay eggs. Even so, Steno found himself struck by the similarity of their reproductive tracts. Then he recalled the appearance of the corresponding structures in women. “Having seen that the testicles of viviparous [live-bearing] animals contain eggs, and having noticed that their uterus opened into the abdomen like an oviduct,” Steno wrote, “I have no doubt that the testicles of women are analogous to the ovaries.” This was a brilliant and daring leap, but, as Steno noted, it relied entirely on analogy. Humans and other animals had structures that looked alike, and therefore they were alike.
FIGURE 8.2. Steno’s drawing of a shark’s jaw, and a tooth seen from the front and back.
Steno had “no doubt” that women have eggs, but neither he nor anyone else had ever seen them. Nor had he made any attempt to solve the mystery of how the eggs made their way from ovary to uterus. But he had made a claim, in print, before anyone else. Steno had planted a flag.
Jan Swammerdam was another brilliant anatomist, a friend of Steno’s almost exactly the same age, and perhaps even more pious and more tormented by guilt. A Dutchman like de Graaf, Swammerdam had a full measure of his countryman’s ambition and competitiveness but none of his rowdiness.
Swammerdam had a newly minted medical degree, like de Graaf and Steno, but he never practiced. Instead, he pursued his own anatomical investigations with the obsessiveness that marked all his endeavors, while relying on his father’s grudging financial support. In his marathons at the dissecting table, Swammerdam neglected his prayers. Recalling his misdeeds, he burst into tears. “For it was as if a warring host were there within my spirit, the one party compelling me to cling to God, the other, with infinite arguments, to go on in my [pursuit of] curiosities.”
In 1667, at the same time that Steno was pondering shark teeth and human ovaries, an anatomy professor from Swammerdam’s university days recruited him to help with a dissection. The two men set to work dissecting a female corpse, paying special attention to the uterus and Fallopian tubes. Like Steno, they made a point of noting the strong resemblance between the ovaries in humans and in egg-laying animals. Like de Graaf (although a few years before him), they observed and dissected small protuberances within the ovaries that they decided were the long-sought eggs (or perhaps structures that contained the eggs).
Swammerdam, whose drawing skills matched his formidable anatomical gifts, prepared illustrations. He went further, using a technique he had mastered for preserving organs in alcohol and injecting their vessels with red or yellow wax, which produced lines like the roads on a map. One lovingly preserved uterus made its way to the Royal Society, where it occupied a place of honor.
Almost inevitably, the friendship that had once bound de Graaf, Steno, and Swammerdam turned to rancor and jealousy as they squabbled over priority. They scrambled to get something into print and flung insults and accusations back and forth. In the long view of posterity, the stakes seem lower. All three men had grasped the same great truth—women have eggs—at virtually the same time. But it was Regnier de Graaf who not only saw the truth but devised an experiment to show it.
NINE
THE EGG, AT LAST
PROUD AS HE WAS OF THE DISCOVERIES HE HAD REPORTED IN HIS book on male anatomy, De Graaf knew that it would be the companion volume, on females, that would make his name. A New Treatise Concerning the Generative Organs of Women appeared in 1672, four years after his volume on men. De Graaf dedicated the new work to Cosimo III, the Grand Duke of Tuscany. Such wooing of the wealthy and powerful was customary. But de Graaf also meant to claim his place in a daunting lineup.
Galileo had dedicated one of his great works, The Starry Messenger, to Cosimo II, also a Grand Duke of Tuscany and the grandfather of Cosimo III. The Starry Messenger contained the first report on a new invention, the telescope, and announced a startling picture of the heavens. Unlike Galileo, de Graaf wrote in his dedication to the grand duke, he had not gazed on distant stars. But he, also, had done great things. He had “made bold to strip off Nature’s robe”—it is hard not to picture Mother Nature crouched over and trying to cover her naked body with her hands—and thereby revealed “the whole workshop of human manufacture and its tools.”
The new book was as ambitious as its dedication implied. First, de Graaf took an axe to conventional wisdom. He scoffed at the one-sex, two-semen model: “The notion of some people that the vagina corresponds with the penis of males, differing only in being inside rather than out, we say is ridiculous. The vagina bears no similarity at all to the penis.”
Nor were the fluids produced by the two sexes comparable. De Graaf noted, with his customary briskness, that “certain females… with lascivious thoughts, frisky fingers, or instruments devised contrary to decent morals, wickedly stir themselves up to such a pitch that they eject copious quantities of this kind of matter.” (“In libidinous women,” he added, “the mere sight of a handsome man” was enough.) But this fluid was not semen, de Graaf insisted, and he moved on.
He began with a no-frills summary of sexual ABCs. First came a remarkable tribute to God the designer. “The woman’s vagina is so cleverly constructed that it will accommodate itself to each and every penis; it will go out to meet a short one, retire before a long one, dilate for a fat one, and constrict for a thin one. Nature has taken account of every variety of penis, and so there is no need solicitously to seek a scabbard the same size as your knife. Through the beneficence of the Creator you can find one anywhere.”
He debunked folk beliefs. Menstrual blood did not turn crops sterile or do any other harm; “menstrual blood is of its nature a benign fluid.” The size of the nose had nothing to do with the size of the penis. Modern anatomists like Columbus and Falloppius, who both “claimed the glory” of having discovered the clitoris, had done no such thing. The clitoris was old news, de Graaf declared, though it had been mislaid for two thousand years. Hippocrates and other
ancient writers had known all about it, as had women since the dawn of time.
De Graaf proceeded to consider the organs directly involved in conception and pregnancy. His discussion of the uterus almost exactly anticipated that of the twentieth-century anatomist Frank Gonzalez-Crussi, who lamented that humankind’s first home has “a most unfortunate topography: a bag of urine in front, a repository of excrement behind.” De Graaf’s take was more philosophical. The uterus was “set between the bladder and the rectum as though between two pillows,” he noted. “Some have thought that the purpose was that men, who are born of fragile and perishable material between dung and urine and are destined to be resolved into earth and cinders, should, when they remembered their vile and abject condition, fold the wings of their pride.”
The uterus itself contained mysteries that would further dampen the pride of any would-be investigator. How did this organ, shaped “like a pear which has been slightly squashed,” perform its nurturing role? How did it know when the time had come to deliver the baby within it? “Writers of the sharpest wits… cannot understand it,” de Graaf conceded. “Thus, that which comprehended these writers does not allow them to comprehend it.”
All this brought de Graaf to his most important point and moved him a crucial step ahead of the formidable William Harvey. What Harvey believed—that mammals had eggs—de Graaf had seen. He had looked at all sorts of animals, egg layers and live-bearers, and all of them “have ovaries full of eggs, and the eggs of the [mammals] are fertilized and reach the uterus in the same way as in birds.” (And de Graaf’s eggs, it is worth noting, were eggs in the proper, biological, sex-cell sense of the word.)
De Graaf made sure no one could miss his point: what was true of other female animals was true of women, as well. “Since all this can be observed in cows, ewes, and other animals which I have dissected in large numbers, everyone will admit that in women, who also have eggs in their ‘testicles’ and the tubes annexed to their uterus, as the brute beasts do, generation takes place in the same way.”
The Seeds of Life Page 9