Suddenly his studies were interrupted by tragic news from the United States. On December 29, 1792, when Hosack had been in Edinburgh for about three months, his son, Alexander, died in New York. American infants perished regularly from diphtheria, smallpox, cholera, pneumonia, and a host of other diseases; perhaps one of these had killed Alexander. Hosack’s father paid for a coffin in January. Hosack remained in happy ignorance for many weeks as the news made its way to Scotland. When he learned of the death, he may well have felt a measure of guilt about his decision to leave Kitty and Alexander. From that moment forward, his devotion to medicine would be tinged with the melancholy wisdom of personal loss. His son had survived only six months.
* The active ingredient of Peruvian bark, quinine, would not be isolated until around 1820. The name malaria comes from mala aria or bad air, a reference to the association of fetid marshes and swamps with the disease. Researchers would not confirm mosquitoes as the vector for malaria until the late nineteenth century.
† The remains of more than four hundred people were reburied, and their resting places now form part of the African Burial Ground National Monument, dedicated in 2007 and administered by the National Park Service.
‡ The farmhouse that the Dyckmans built in the 1780s can still be visited today at Broadway and 204th Street, in the Inwood neighborhood of Manhattan.
Chapter 2
“AN ENDLESS SOURCE OF INNOCENT DELIGHT”
MOST OF SCOTLAND LIES TO THE NORTH OF EDINBURGH, draping in green-velvet layers over soft mountains and pausing briefly on the shores of glassy lochs. Travelers on the moss-walled country lanes could find themselves in a rainstorm one moment and in a shimmering, backlit valley the next. In the spring of 1793, Hosack set out by stagecoach on a journey through this landscape. He was bound for Elgin, the town his father had left behind at midcentury to sail for America and the French and Indian War. Hosack reached the northern coast after more than a week of travel. As the sea appeared, the landscape flattened out and gave way to an enormous expanse of sky. Here swallows skimmed the earth at dusk and curly-horned sheep grazed in silhouette against the blue-green curtain of the sea.
Elgin was a handsome town lined with medieval arcades. A five-minute walk from the central marketplace took Hosack to the vaulting ruins of Elgin’s thirteenth-century cathedral. At the end of the fourteenth century, an adulterous nobleman named Alexander Stewart (also known as the Wolf of Badenoch) led a marauding band of Highlands men to Elgin to avenge Stewart’s excommunication by its bishop. They burned the town together with its cathedral. When Hosack arrived four hundred years later, the empty windows of the ruined towers still traced high arcs against the sky.
Hosack loved the north. At Elgin, he made the acquaintance of two of his uncles, and through them, he met the Brodie family, who lived just outside Elgin in a sand-colored castle. Visitors like Hosack who rode up the long, straight carriage drive to Brodie Castle saw a cluster of towers, chimneys, and battlements rising before them, the whole surrounded by well-tended lawns and forest trees. When Hosack arrived in the spring of 1793, the laird of the clan was James, 21st Brodie of Brodie. James welcomed his young American guest with moving warmth, insisting that he stay in the castle with the family. Hosack found himself dining not only with a laird but also with a duke and a duchess, for James’s niece had married the Duke of Gordon, and the couple were in residence during Hosack’s visit.
He lingered at Brodie Castle for a week. James was an ardent botanist and horticulturist who loved to ramble in search of new plants. He adored the Scottish countryside so much, in fact, that after being elected to Parliament in the year following Hosack’s visit, he declared he was “really unhappy” in London and decided to return to Scotland. The grounds of James’s castle contained formal French gardens, a pond, and a ninth-century slab carved with Pictish symbols. Lindens and beech trees spread their boughs over broad walkways. Nearby, Hosack could stroll along the banks of the Muckle Burn, a pretty stream crisscrossed by arched stone bridges, or he could follow the River Findhorn as it wound through the meadows toward the North Sea. These idyllic days reinforced Hosack’s desire to learn all he possibly could about plants, as his resolve to study medical botany became pleasantly jumbled with the glamour of a botany-mad nobleman and the picturesque seaside setting. He tore himself away from the Brodies and Elgin to travel south again, and in May 1793 he left Scotland for the botanical capital of the Western world.
LONDON.
Hosack took lodgings in the city with another young man who had studied with Benjamin Rush in Philadelphia. Then, probably on the recommendation of his Edinburgh professors, he set out for a neighborhood called Brompton, on the leafy western outskirts of town. He was looking for a man named William Curtis, whose entire existence had been devoted to acquiring exactly what Hosack now coveted: intellectual dominion over the kingdom of flora.
Curtis was forty-seven years old, a short and thickset man with a round face that turned red when he tramped through the fields at his customary breakneck pace. In spite of his sunny disposition, Curtis could sometimes seem aloof, but this was only because he felt shy conversing with men he thought knew more than he about science. He needn’t have worried—he was the greatest practical botanist in the whole of Britain.
From earliest boyhood, Curtis had loved roaming through the pretty Hampshire countryside where he had been born. To him the natural world was “an endless source of innocent delight,” and he had been miserable when his father sent him away to study medicine. He could still recall thirty years later how badly he had longed to bolt back outdoors, away from “the putrid air of the dissecting room” and “the noxious fumes of the laboratory.” After this awful experience, he decided to become a gardener and botanist so he could spend the rest of his life surrounded by trees, birdsong, and the scent of flowers.
For six years, Curtis worked as the Demonstrator of Plants at the Chelsea Physic Garden, a medicinal garden on the Thames run by the Society of Apothecaries. His job was to use the garden’s collections to teach aspiring apothecaries and doctors. Curtis’s clinical experience mingled perfectly with his excellent horticultural instincts. Whereas many previous British botanists had thought of plants as so many opportunities to beautify the kingdom’s gardens and bring delicacies to its tables, Curtis also saw an opportunity to improve British medicine. He was determined to learn about the possible virtues—the eighteenth-century term for the healing powers of a plant—that might lie hidden in the heaps of new species constantly arriving from around the globe. But he was equally interested in discovering the unknown medicines growing wild along England’s country lanes. He dreamed of creating his own garden filled with native and foreign plants of all possible species in order to conduct systematic research of a kind unprecedented in Britain. Finally, Curtis waved farewell to his steady salary and in 1789 founded a botanical garden of his own in Brompton.
William Curtis
By the summer of 1793, when Hosack came looking for Curtis, the Brompton Botanic Garden was brimming with life and color. At the southern edge of Curtis’s garden, Hosack first encountered a porter’s lodge and a gate marked Botanic Garden, open to subscribers. He entered and found himself on a wide gravel path. All around him was a tidy patchwork of flowers, grasses, shrubs, and trees, but Hosack’s feeble grasp of botany turned Curtis’s orderly kingdom into an inscrutable mess. To his left was a cluster of rugged-looking plants and beyond them were dozens more unfamiliar species. Nearby lay a parcel of what appeared to be grass. At the far end of the garden was a small greenhouse filled with specimens from all over the world. But it was in the very first plot to Hosack’s right that he found the plants he had come for: dozens of medicinal specimens, their labels inscribed with the Latin names familiar from his Edinburgh medical textbooks.
Hosack summoned up his considerable powers of persuasion and introduced himself to Curtis. The latter was no longer offering private instruction, burdened as he was by the work of tending his g
arden, publishing on botany, and exchanging plants with naturalists around the globe. He must have found this young American’s enthusiasm irresistible, however, because he agreed to take him on as a private student. So began a summer Hosack would remember with pleasure for the rest of his life. He signed up as a Brompton subscriber and received a copy of the garden regulations, which included a ban on dogs and also on “inconsiderate or designing” visitors who made “bouquets of the flowers.” His new teacher had rather formal manners, yet at the same time he was pleasant and helpful.
As the two men strolled along the gravel paths, Curtis explained how he had organized his three and a half acres of garden. It was only recently that most European botanists had adopted a unified system for naming and classifying plants. For hundreds of years, people had identified new plants using unwieldy and incommensurate systems. Then, in the middle of the eighteenth century, Carl Linnaeus, a Swedish botanist who had initially trained as a physician, swept away the old botanical order with a series of pathbreaking books: Systema Naturae in 1735, Philosophia Botanica in 1751, and Species Plantarum in 1753. Most plants, Linnaeus argued in Systema Naturae, could be divided into groups according to the varying numbers of their stamens and pistils—their sexual organs. This new sexual system was a simple, powerful scheme that botanists could henceforth use for each plant they newly identified. But Linnaeus also realized that the thousands of plants already known to botanists would now need reclassifying according to the sexual system. In the preface to Philosophia Botanica, he confessed to being “frightened” by the scale of his own project, but he overcame both his anxieties and a severe attack of gout to produce Species Plantarum. In this mammoth work, he advocated a simple two-word Latin combination for each plant (first its genus, then its species) and proposed new names for around six thousand known plants. He also laid out a system for naming future discoveries and urged it on his fellow botanists, whom he undiplomatically accused of favoring “pompous expressions and flowers of rhetoric.”
Some fellow botanists were offended by Linnaeus’s tyrannical tone. In France, especially, Linnaean botany did not take hold easily. French botanists preferred the “natural system,” an approach articulated by Bernard de Jussieu (and later his nephew Antoine-Laurent de Jussieu) that grouped plants together on the basis not only of their sexual organs but also their flowers and fruits. In Britain, too, some botanists were reluctant to adopt the Linnaean system—but not William Curtis, who loved the clarity of Linnaean nomenclature and the ease with which new plants could be classified by the numbers of their stamens and pistils. Curtis was so enthusiastic that he published his own easy-to-follow illustrated guide to the sexual system in 1777, and he taught Linnaean botany to all his students, including Hosack.
Curtis also launched two ambitious publishing projects that brought Linnaean botany to laypeople across Britain and made him famous. The first was a lavishly illustrated compendium of all the plants in the London region entitled Flora Londinensis, which Curtis financed through subscriptions. Beginning in the late 1770s, his subscribers periodically found among their letters and parcels a bundle of hand-colored engravings about the size of a large tea tray. Curtis could not draw very well himself, but he had a reputation for being able to spot even the tiniest inaccuracy in other people’s plant drawings. He found his finicky standards completely exceeded by a gifted young artist named James Sowerby, one of several he hired to execute illustrations for the Flora. Curtis accompanied each plate with the plant’s Linnaean and common names and its usual habitat—near sandy beaches, deep in the woods, and so on. He also included chatty descriptions of each species. For example, writing of an herbaceous plant (Arum maculatum) whose roots were used to treat asthma, Curtis noted that it was sometimes called “Lords and Ladies” because its flowering parts resemble copulating genitalia and thus “attract the notice of children in the spring.” In true Enlightenment fashion, Curtis exhorted his readers to put down their botany books and go outside to make their own observations. “To know the Fungi well, we must watch them daily and yearly; in short, we must live with them.”
The volumes of the Flora Londinensis were groundbreaking and beautiful, but they were also terribly expensive to publish. Curtis could never seem to sign up quite enough subscribers to underwrite the project. A friend described the project as the “poor dear Fl. Londinensis—your glory, your best friend your everything.” But then Curtis hit upon a much more lucrative way to initiate laypeople into the delights of Linnaean botany. In 1787 he began publishing a one-shilling monthly called the Botanical Magazine, filled with pictures of the exotic ornamentals British gardeners were increasingly eager to cultivate at home. The craze for Curtis’s new magazine brought him two thousand subscribers a month.* By the summer of 1793, when Hosack arrived at the Brompton Botanic Garden, Curtis was the undisputed master of the Linnaean system in Britain.
Hosack was thrilled to be studying with the famous naturalist whose publications had escorted botany out of the botanical garden and onto the grounds of Britain’s country estates. But to Hosack the most exciting aspect of Linnaean botany was not that troops of ladies and gentlemen could now rattle off Latin binomials as they picked their way through the woods. It was that Linnaeus had flung open a door to the discovery of new medicines.
Hosack knew from his Edinburgh teachers that physicians and apothecaries had for centuries relied on clumsy and inaccurate rules to try to divine the medicinal properties of specific plants. People kept holding out hope, for example, that plants of a particular color or smell or shape would have similar virtues and could thus treat similar illnesses. Linnaeus pointed out in Philosophia Botanica that these assumptions had proved “false and delusive.” He had therefore come up with a new framework, which he captured in a few simple new rules that mapped neatly onto his equally neat plant classification system. Plants of the same order, he predicted, would likely turn out to have at least some overlapping medical properties with one another. Plants of the same class would share most of the same virtues with one another. And plants of the same genus would tend to overlap entirely in their virtues. By way of example, Linnaeus noted that the various known species of Convolvulus, a genus in the bindweed family that included morning glories, all appeared to have purgative effects on the body.
This was a bold new approach to medical botany, but Linnaeus acknowledged that there was one hurdle. Anyone who was interested in discovering the virtues of an unfamiliar species of plant would need to know what properties were associated with other plants in the same class, order, or genus. Curtis, leafing through his volumes of Linnaeus, was inclined to agree. He also thought that asking medical students to memorize these properties from mere written descriptions of plants was at best inefficient and at worst fatal. It was only in a botanical garden like Brompton, Curtis thought, that medical students could learn enough about medicinal plants and their internal structures to go forth and find new ones. To help students like Hosack understand the exciting promise of Linnaean medical botany, Curtis labeled each of his medicinal plants not only with its Latin and common names but also with the page number from the Edinburgh New Dispensatory where that particular plant’s virtues were discussed. This would help the students commit to memory the link between the medicinal uses of the plant and the way it looked when it was actually growing. Then they would be prepared to compare that knowledge to the new plants they would encounter—maybe even discover—in the future.
All that summer at Curtis’s side, Hosack memorized plant names, studied their medical properties, and worked on his classification skills. For the medicinal beds, Curtis had chosen dozens of native plants commonly used by British physicians as well as many other plants from across Europe and around the world. Hosack already knew from his own studies that different medicinal plants had different effects on the body. Some plants, for example, functioned mainly to ease pain—such as Solomon’s seal (Convallaria multiflora), with its ladders of bell-like white flowers dangling along the stem
, shiny leaves, and roots that could be mashed into a poultice to reduce inflammation. Other plants could be used to help purge a sick body of offending fluids, a critical function in the humoral understanding of the body. Which of these plants a doctor decided to prescribe would depend on his patient’s particular imbalance or ailment. When faced with a constipated patient, for example, he might choose blue succory (Cichorium intybus). Sometimes known as chicory, it had leaves, stalks, and roots that yielded a juice capable of inducing mild diarrhea. Pot marigold (Calendula officinalis) likewise acted to relieve constipation, but as the Edinburgh New Dispensatory noted, it was also “celebrated in uterine obstructions”—meaning that it flushed out miscarriages.
Curtis was also growing plants used by doctors to keep unruly excretions inside the body. For example, the leaves of common agrimony (Agrimonia eupatoria), a spindly plant with fragrant yellow flowers, possessed antidiarrheal properties helpful to patients afflicted with wasting diseases such as scurvy, which involved a “lax state of the solids.” Most of Curtis’s medicinal plants could be used in treating more than one illness, but some had long been linked with a single disease. He was raising a pretty perennial called great blue lobelia (Lobelia siphilitica), whose smelly, vomit-inducing roots Native Americans used to treat venereal disease. He had also planted the widely useful vervain (Verbena officinalis) in his medicinal beds, but he laughed off the idea that vervain could cure scrofula (an infection of the lymph nodes) when tied with a white satin ribbon around the patient’s neck. This was nonsense, he said, “even making the greatest allowance for the powers of the imagination.” Curtis could scoff at old medical myths, but the painful truth was that no one truly knew yet just what made a particular plant effective against a given illness. And no one—not even Linnaeus—had yet come up with a reliable way to discover and isolate new plant-based medicines.
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