IN THE FIRST HALF of the nineteenth century, the most famous—or infamous—exponent of evolution was not the anonymous author of Vestiges of the Natural History of Creation, but the French naturalist Jean-Baptiste Lamarck, who died in obscurity in 1829. It has been stated that Lamarck’s “volitional” explanation of organic development has been caricatured. However, his observations on the inheritance of acquired characteristics—that is, characteristics acquired as a consequence of the use or disuse of organs and parts—left an indelible stamp on the minds of naturalists, including Wallace. Lamarck’s view of how the wading bird got its long legs, for example, reads like one of Aesop’s fables: “[W]ishing to avoid immersing its body in the liquid, it acquired the habit of stretching and elongating its legs. The result of this … is that individuals will find themselves elevated as on stilts, on long naked legs.”1 Such “unphilosophical” statements left open to ridicule his more important theory of evolution, put forth at the turn of the century in his book Philosophie zoologique, in which he argued in favor of a “natural” process of organic change, the descendants of common parents deviating “indefinitely from [the] original type,” in an inevitable progression from one form to another, up the ladder of complexity—the same idea espoused by the author of Vestiges forty years later.
Lamarck’s speculations were one of the themes of Sir Charles Lyell’s Principles of Geology, an influential three-volume study published in the early 1830s. Lyell, who had been born in 1797 into a family of Scottish gentry and studied at Oxford, was a barrister who chose to pursue his interests in geology rather than practice law. On scientific grounds, he rejected the tradition of using Scripture to support geologic theories. Without denying the truth of the Bible itself, he did not accept a literal interpretation of the story of Genesis.2 Sometime in 1845 or 1846, Alfred read Principles, a book that would play a crucial role in the articulation of his own theory of evolution—as it would in Darwin’s. But Lyell, despite his antiscriptural stance, was not an evolutionist. In fact, his book attacked the idea of evolution, especially the view advocated by Lamarck. Lyell perceived as dangerous Lamarck’s denial of the part played by divine intervention in the creation of species and, worse, his suggestion that humans were derived from lower forms. “Henceforth his speculations know no bounds,” Lyell remarks in Principles:
He gives the rein to conjecture, and fancies that the outward form, internal structure, instinctive faculties, nay, that reason itself, may have been gradually developed from some of the simplest states of existence,—that all animals, that man himself, and the irrational beings, may have had one common origin … ; in fine, he renounces the belief in the high genealogy of his species, and looks forward, as if in compensation, to the future perfectibility of man in his physical, intellectual and moral attributes.3
Only verae causae—true causes—belonged in a scientific work, Lyell stated, and evolution was not a vera causa because it was not supported by factual evidence. Facts, he believed, supported the creationist theory. Species were fixed entities, derived from a single pair of individuals. Variations occurred “within certain limits,” but “transmutation” never happened. Species lived out a natural life span, died, and were replaced by other species. He felt that embryology did not support the idea of gradual transmutation of one species into another; rather, it disclosed “the unity of plan” that runs through the animal kingdom, especially vertebrate animals. Lyell’s concept of the species problem differed little from William Swainson’s.4
At the time, Wallace made no comments about Lyell’s ideas on species. But even as early as 1846, he would have rejected them in spite of Lyell’s great powers of persuasion and his “philosophical,” or inductive, method of reasoning; in 1846 Wallace was a disciple of Vestiges, and once he was converted to an idea he never let go. Wallace found Lyell’s arguments about geologic processes persuasive, however, and his use of induction—the building of fact upon fact to support a hypothesis—appealed to Wallace’s logical mind.
Lyell’s signal contribution to the science of geology was his attack on catastrophism, a theory advanced by the renowned French paleontologist and anatomist Georges Cuvier. Catastrophists (in Lyell’s interpretation) believed that the past history of the earth had been more violent than its present. Massive forces had uplifted the great mountain chains almost instantaneously; valleys had been created by sudden and devastating ruptures in the earth’s crust; volcanic eruptions had spewed out lava, rock, and ash in volumes inconceivable now; periods of worldwide deluge had alternated with periods of quiescence. Whole floras and faunas had been wiped off the face of the earth during such catastrophic events and replaced with new creations, which, in turn, had been annihilated and replaced. Lyell dismissed the assertions of the catastrophists as fantasies, mere speculation with no basis in fact. He held that most geologic change was gradual and that where it appeared to be abrupt, the gaps in the story would be filled in as more evidence was gathered through the work of geologists. There was continuity between the geologic past and the present, and he noted many points of analogy between them. The present-day consequences of volcanoes and earthquakes, of floods and drought, were keys to the secrets of a past that catastrophists asserted was unknowable. Mountains and valleys formed over millions of years, Lyell said, uplifted and whittled down little by little through the action of wind, sand, sun, water, and other natural agencies, a process whose hallmarks were visible to any keen observer. Moreover, he showed that throughout the Tertiary period (which he subdivided into four successive epochs: the Eocene, Miocene, Older Pliocene, and Newer Pliocene), the assemblage of species had changed gradually—older species becoming extinct one by one as they were replaced by newer species. This uniformitarian doctrine, first formulated by the Scottish geologist James Hutton in 1785, emphasized the notion of deep time—time on an immense scale, almost beyond comprehension. And over such a vast amount of time, tremendous change was possible.5 Lyell’s uniformitarianism left a deep impression on Wallace—as deep as Thomas Malthus’s idea of the struggle for existence and Robert Chambers’s theory of organic evolution.
In September 1847, Wallace toured the extensive collections of specimens housed at the Muséum Nationale d’Histoire Naturelle of the Jardin des Plantes in Paris. His sister Fanny, who had returned from the United States, had offered to commemorate her reunion with her family by taking Alfred and John to Paris for a week. Fanny was fluent in French and acted as interpreter. A visit to the insect room of the British Museum on the journey home impressed him even more. The sheer number of beetles and butterflies assembled from remote regions of the globe overwhelmed him. He left feeling intoxicated by the allure of exotic places—especially the tropics, where species abounded in profusion.
In a letter to Henry Bates shortly after returning, Alfred reiterated his desire to travel abroad, a follow-up to a discussion the two men had had earlier in the summer about collecting somewhere in the tropics. “I begin to feel rather dissatisfied with a mere local collection,” Alfred wrote that autumn. “Little is to be learnt by it. I should like to take some one family to study thoroughly, principally with a view to the theory of the origin of species. By that means I am strongly of [the] opinion that some definite results might be arrived at.” Mindful of the vast number of entomological specimens at the British Museum, Alfred proposed that he and Henry go to some “unharvested” region of the Amazon to comb the banks of the world’s mightiest river for botanical and zoological specimens, financing their way by selling duplicates of their collections in London and gathering as many facts as possible to solve that mystery of mysteries, the origin of species, the great riddle that occupied the thoughts of the finest philosophical naturalists of the era.6
It was a daring plan, conceivable only by one with the arrogance and inexperience of youth. Swainson had warned the aspiring naturalist against such a proposition: “We recommend no one to make pecuniary speculations in subjects of natural history, under the idea that the prices to be obtained will repay them for the cost or trouble of their original acquisition.”7 Neither Bates nor Wallace had official sponsorship, and their middle-class status and inexperience would not persuade wealthy patrons to offer private support for an expedition with an uncertain outcome. Previous explorers had been independently wealthy or had been hired as naturalists by the Royal Navy. Alexander von Humboldt, a German aristocrat, had financed his five-year expedition to South America and spent his private fortune on his travels, subsequent publications, and scientific writings; Darwin’s voyage around the world was underwritten by his father; Darwin’s friends Thomas Huxley and Joseph Hooker doubled as medical officers and naturalists onboard naval ships. With no credentials except enthusiasm, Bates and Wallace could never hope to find work as traveling naturalists aboard an ocean-bound vessel.
But Wallace’s plan was not as impulsive or ill-considered as it seemed. Since moving back to Neath in 1845, he had been reading extensively in natural history. He was indulging his passion for his “favorite subject—the variations, arrangements, distribution, etc., of species.”8 The Mechanics’ Institute library contained the best books available for any eager student, including Vestiges of the Natural History of Creation and Principles of Geology. Wallace had by then tackled Humboldt’s forbidding three-thousand-page chronicle, Personal Narrative of a Journey to the Equinoctial Regions of the New Continent, which was de rigueur for anyone contemplating travel as a naturalist. He also had read Darwin’s Voyage of the Beagle at least twice. Wallace later said that more than any other published accounts, Darwin’s Voyage and Humboldt’s Personal Narrative had fired his imagination and filled him with a zeal to travel to some unexplored region of the earth for the purpose of making a contribution to natural science.9
Humboldt left for Spanish South America in 1799 and was given permission to explore the Amazonian and Andean regions of present-day Venezuela, Colombia, Ecuador, and Peru. One of his scientific missions was to demonstrate a connection between the Orinoco and Amazon Rivers, a problem that had puzzled geographers. But he and his traveling companion, Aimé Bonpland, never reached the sources of the Orinoco, which were in Brazil, an area off limits to private travelers at that time. Over a period of five years, however, he collected an immense amount of data. He was the first to create topographic maps of floral habitats. One of his most famous illustrations was a foreshortened and bisected view of Chimborazo, an Ecuadorian volcano, half of which was a realistic representation of the forested flanks and snow-capped peak, the other half a chart listing every plant collected on the volcano, with its precise location noted. Humboldt also invented an entirely new genre of travel literature by including objective descriptions of geology and natural history, details of his daily experiences, depictions of the customs and institutions of the indigenous peoples, and subjective impressions, judgments, and emotional reactions—all of which he combined into a seamless narrative with polymathic skill, aesthetic sensitivity, and literary craftsmanship. Humboldt’s methodology, based on the precise and accurate recording of his observations and measurements, and the high quality of his written account set the standard for all future scientific travelers.10
Darwin also traveled for five years (1831–1836), most of which he spent sailing around the South American continent. As the Beagle sailed along the coast, Darwin, the ship’s resident naturalist, made numerous excursions into the interior, collecting rocks and specimens of the local flora and fauna and examining fossils. In September 1835, the Beagle reached the Galápagos Islands, which would become famous as the epiphany of his travels. “It never occurred to me,” Darwin later wrote, “that the productions of islands only a few miles apart, and placed under the same physical conditions, would be dissimilar.”11 He was also struck by the resemblance of the fauna of the islands to species on the nearby continent. Such “singular relationships” were among the observations that made an evolutionist of him, though there is no explicit statement of this in his travel book. By the time he returned to England in October 1836, Darwin had matured to such a striking degree both emotionally and intellectually that his father, who put little credence in phrenology, remarked to Darwin’s sisters that “the shape of his head is quite altered!”12
Wallace told Bates that he admired Darwin’s writing style, which was “so free from all labour, affectation, or egotism, and yet so full of interest and original thought.” As another point in Darwin’s favor, he noted that Darwin was “an ardent admirer and most able supporter of Mr Lyell’s views”—referring to Lyell’s uniformitarian ideas about geologic processes, not his thoughts on evolution.13 (Darwin’s ideas on evolution were still a secret.) However, Wallace clearly had more in mind than expressing admiration for Darwin’s Voyage. He longed to produce a similar book, full of equal interest and original thought, about his own exploits in uncharted territories.
The decisive factor that set Alfred’s sights on an expedition to South America was William Henry Edwards’s book A Voyage up the River Amazon: Including a Residence at Pará.14 Edwards, who had been born in 1822, was a respected American amateur naturalist who had written an account of his travels in Brazil in 1846 in the kind of purple prose that would sweep any headstrong young man off his feet—and Wallace’s feet were well off the ground after he read about the wonders in store for a prospective traveling naturalist. Edwards portrayed Brazil as the naturalist’s promised land, an Eden teeming with wildlife and exotic natives. Pacas and agoutis, motmots and chatterers, goatsuckers and manakins, and other birds and animals with strange names—all easily plucked like fruit from the bountiful branches of Brazilian trees—imbued that country with a magical aura that the two young men found irresistible. The region, populated by “Negroes of every shade of color” and beautiful Indian girls fluttering by like “visions,” offered ample rewards for traveling anthropologists and ethnologists. The markets were cornucopias of exotic foods, the climate was one of the healthiest on earth, and the inhabitants were eager to assist the foreigner in every endeavor.15
Besides Edwards’s earnest account, there were good reasons for selecting Brazil as a destination for scientific investigation. First, few places on earth boasted the biodiversity of the Amazon River basin, which included much of Brazil and parts of Peru, Ecuador, New Grenada (Colombia), Venezuela, and British Guiana (Guyana). Edwards’s book testified to the richness of the fauna accessible to the amateur. Second, only a handful of explorer-naturalists had penetrated into the heart of the Amazon. Two Germans, Johannes Baptist von Spix and Carl Friedrich von Martius, spent eleven months (July 1819–June 1820) ascending the Amazon River, beginning at Pará; and the Englishman Charles Waterton made four journeys between 1804 and 1824 to Guiana, an English colony on the northeastern border of Brazil. But their investigations were far from exhaustive.16 Robert Schomburgk, a German-born English explorer, also limited his explorations to Guiana, while Darwin focused on the Spanish colonial states to the south and west of Brazil. Humboldt attempted to enter Brazil, but he was barred by the Portuguese colonial government because of his radical political views; his admiration for the French Revolution and his defense of abolitionism were well known to Portuguese authorities. After Dom Pedro I had declared independence from Portugal in 1822 and named himself emperor of Brazil, no foreigner could travel in Brazil. Civil unrest prevailed there for the next twenty years, until a constitutional monarchy was established in 1844. An opportunity thus existed for some enterprising young naturalist to do what Humboldt had been unable to do: explore scientifically the watershed between two of South America’s greatest rivers, the Orinoco, which originated somewhere in Brazil, and the Amazon, whose important tributary, the Rio Negro, arose in Spanish territory.17 The vast, biologically unexplored Amazon therefore excited great interest in the London scientific community and was the perfect place for two neophytes to make a name for themselves.
The third reason for traveling to Brazil was the relative inexpensiveness of a journey to South America. The cost of living in Pará was low and financial risk minimal as long as a steady stream of specimens could be shipped back to London. And, fourth, a network of foreign residents provided a solid infrastructure, a safety net for the collector unused to living in a remote land far from the comforts of home. Britain, now at the height of its imperialism, maintained a meddlesome presence in South America, even if territorial conquest was low on its agenda. Always looking for recipients of its exports, by threatening to use its military might Britain ensured that Latin America’s doors never closed to its merchants (or other British citizens).18
There were considerable disadvantages, however. Humboldt and Bonpland had traveled on a swollen, raging, alligator-infested river in a small boat with a bottom so worn that it threatened to fall apart. In Argentina, Darwin had found himself in the midst of a revolution. Accounts by other travelers spoke of the stealth and malice of the Indians, who killed with silent darts dipped in curare. Above all other dangers loomed the threat to one’s health. Plagued by mosquitoes, frequently soaked to the skin, emaciated as a result of inadequate food, and exhausted by their efforts, Humboldt and Bonpland became severely ill—Bonpland to the point of death—on their return journey through Colombia to the Caribbean coast. “The dangers do not come from wild Indians or snakes or crocodiles or jaguars,” Humboldt wrote, “but, as they naïvely say, from ‘el sudar y las moscas’ (sweating and mosquitoes).”19 More explorers died from tropical diseases than from shipwrecks or the poisoned darts of murderous indigenes. The prevailing opinion throughout the nineteenth century was that there was “something in the tropical climate inimical to Europeans.” No distinction was made between the tropical climate and those diseases endemic to the tropics. Equatorial regions were associated with various forms of lethal “malarial fevers.”20
If Bates hesitated, he was quickly persuaded by Wallace’s passionate and eloquent arguments in favor of the vagabond life of an explorer-naturalist in the “torrid zone,” as Humboldt called the equatorial rain forests of South America. No longer willing to maintain a foundering architectural business, Alfred had run out of ideas for a useful occupation, while Henry detested his latest job as a clerk in a brewery. Both men had little to lose and much to gain. Their hearts were now set on a journey to the Amazon.
Filled with all sorts of romantic notions about the American tropics, Bates and Wallace began to make arrangements for an expedition to Amazonia. Bates’s father offered to lend the pair a small sum of money, which was added to their personal savings.21 In preparation for his eventual departure for Brazil, Alfred and his brother John closed their architectural business. Wallace tells us nothing about what his family thought of his extraordinary decision to set out for the tropics. Since he always seemed to maintain good relations with his mother and siblings, they must have given his plan at least tacit approval. But his decision caused problems. John, who did not have enough surveying or other work to support the family, rented a small house and a few acres of pastureland near town. Mary Anne and Fanny remained with him to do the housework, while he went daily by small pony cart into town to sell milk from the cows he kept. But he made too little money to pay the rent, and in the spring of 1849 he decided to give it all up and sail for California during the mad rush for gold. Fortunately, Fanny married Thomas Sims that year and moved to London with her mother. Herbert, who was employed at the Neath Iron Works, stayed behind in Wales.22
Wallace and Bates agreed to meet in London in March 1848. Their primary object was to study the extensive collections of animals at the British Museum, the breadth of whose holdings symbolized England’s ambitious imperialist agenda.23 The treasure trove was analyzed by many of the most illustrious anatomists and taxonomists of the time, such as the paleontologist Richard Owen and the ornithologist John Gould. Here the two young naturalists familiarized themselves with the fauna of South America, noting the depth and breadth of the existing collection, which gave them an idea of the gaps that needed to be filled.
Many years later, in his essay “Museums for the People,” Wallace would have some harsh things to say about the British Museum. Like most public museums of the mid-nineteenth century, it was as “unsuited for the amusement and instruction of the public” as it was for the purposes of “the scientific student.” Many museums had begun as private collections, which only later were opened to the public. When these collections outgrew their space, Wallace complained, “a temple or palace” was designed to suit its patron’s idiosyncratic taste, with little consideration given to lighting or the logical arrangement of objects. Any specimen was displayed, no matter how imperfect or badly prepared. Quantity, not quality, seemed to be the rule. As new specimens poured in from every region of the world, the task of naming, classifying, and cataloging them outstripped the abilities of curators. Disparate groups of animals, poorly labeled and with no attention paid to geographic distribution, might be exhibited together in narrow side galleries. Access to unexhibited specimens was not always easy, and even when accessible they were often in disarray and carelessly stored.24 Despite all these difficulties, the British Museum was essential to Wallace and Bates’s success in 1848, since its curators were interested in anything novel the two men could send back.
The British Museum was not the only institution interested in a naturalist’s collections. The Royal Botanic Gardens at Kew hired its own legion of botanists to fill its conservatory with as many exotic plants as possible. In the mid-nineteenth century, the massive geometric glass conservatories like Kew were architectural and technical marvels, attracting visitors from all over Europe.25 Wallace and Bates made the necessary pilgrimage to Kew, examining live plants in the humid hothouses and dried specimens preserved in herbaria beyond common view, plying the staff with questions, and feeling their way through the arcane world of academic botany. Although Kew did not hire them to make collections, Wallace and Bates agreed to send back unique botanical samples if the price was right.
By a fortunate coincidence, William Edwards, the author of A Voyage up the River Amazon, was in London at the same time and agreed to meet the two men one evening. No less effusive in person than in his prose and, at twenty-five, not much older than they were, Edwards encouraged Wallace and Bates to go to Brazil and gave them letters of introduction to some of his American acquaintances in Pará, home to the largest American and English expatriate population in northern Brazil.26 On Edwards’s advice, they accelerated their plans to leave England in order to reach Pará by late May, the beginning of the dry season.
There remained the issue of financial support. Convinced by Edwards’s report of the plethora of wildlife, they consulted Edward Doubleday, keeper (curator) of the butterfly collections at the British Museum. Doubleday agreed that if certain conditions were met, two independent traveling naturalists could make sufficient money to underwrite their explorations—particularly since the whole of northern Brazil was very little known and their specimens were thus likely to be novel and attractive. A series of insects had to be as complete as possible, encompassing all known orders. As important as insects were land shells (for example, snails and other terrestrial mollusks), birds, and mammals. The rarer the species, the greater the revenue, with new species commanding the highest prices.27
Their experience limited to gathering plants and insects for their own private collections, Bates and Wallace had a lot to learn about the preparation, storage, and transport of large quantities of natural history specimens. For instructions on how to ship specimens to England, they were referred to the curator of the India Museum in London, Thomas Horsfield, one of the most famous naturalists of the day, who showed them the boxes in which he had shipped his butterflies from Java. Three feet long, two feet wide, and two feet deep, these boxes could hold a large number of cork-lined boards, fitted into vertical grooves about two inches apart, on which the insects were pinned. A large number of specimens could thus be safely packed into a small area, and any that came loose would fall to the bottom of the case and remain unharmed. As the two found not long after arriving in Brazil, such sturdy cases, though ideal for shipping pinned specimens, were far too cumbersome for the roving naturalist, who had to travel as lightly as possible. In the end, they made smaller storage boxes, substituting local soft woods or slices of the midribs of the ubiquitous palms for cork, which was not available.28
Knowing almost nothing about capturing and skinning birds and mammals, Wallace and Bates also needed a crash course in taxidermy. But with so little time left before their planned departure, they realized that most of their education would have to take place in the field. Other explorer-naturalists had been better prepared. While studying medicine in Edinburgh, Darwin had learned the art of taxidermy from a former slave who earned his living stuffing birds, having traveled to Guiana with Charles Waterton in the 1820s. An expert marksman with the zeal and leisure time for hunting and bird shooting, Darwin spent his free summers backpacking, collecting, and chasing wild game.29 Wallace, who seems to have had little experience with a gun, would have to practice shooting before journeying to the tropical forests, whose denizens would be obscured by dense foliage and deep shade. No doubt a large number of specimens would elude him as he progressed along the learning curve.
There were other drawbacks to collecting in a foreign country, however. Preservation posed the greatest challenge: a badly preserved organism bearing little resemblance to its living counterpart was useless. Hard tissues such as shells, bones, beaks, and some skins formed a disproportionate part of what was shipped back to England and the Continent. Soft internal structures, equally important to the taxonomist, would be destroyed if improperly stored. Whole animals placed in “spirits” (alcohol) often became distorted, though the more delicate organs were protected. If a glass jar was not airtight, the alcohol evaporated, destroying the specimen—and a ruined specimen meant lost revenue. An independent naturalist, living hand-to-mouth in hostile conditions, counted every item as a contribution toward his survival and elected to amass the more profitable objects. The philosophical naturalist, though, had to strike a balance between economic necessity and the advancement of scientific knowledge. To make his mark in the world, he needed to obtain specimens of value to the scientist at the university or natural history museum and to procure plants and animals for the shelves of the dilettante, both tasks demanding expertise in taxonomy and classification. In order to identify and classify a specimen properly, it had to be examined with an eye as critical and knowledgeable as that of an expert jeweler examining a diamond.30 The audacity of Wallace and Bates’s expedition lay not in its conception, but in its execution.
The two men were put in touch with Samuel Stevens, an enthusiastic collector of British coleoptera and lepidoptera and brother of J. C. Stevens, a well-known natural history auctioneer. Samuel Stevens was the natural history equivalent of an impresario, acting as agent for many wayfaring naturalists, advertising their work at the leading scientific societies, disposing of their collections, providing a steady supply of cash, and sending his clients in the field the latest information on matters of general scientific interest. He was honest, reliable, and endowed with both common sense and practical knowledge, qualities indispensable to Wallace and Bates. He requested a commission of 20 percent plus 5 percent for insurance and freight. Each insect would bring in 4 pence, leaving 3 pence for the collector—a pittance, but the going rate at the time.31 There was no question that quantity as well as quality was the key to making a profit; this meant not hundreds but thousands of specimens.
Stevens was doubtless instrumental in educating Wallace and Bates in the methods of collecting and preserving specimens, though Swainson had included several chapters on preservation techniques in A Treatise on the Geography and Classification of Animals. Stevens later wrote a treatise on the subject. As a natural history agent, he was the perfect educator, with one eye on science and the other on the bank. His advice was pragmatic. Echoing Humboldt, he advised his readers that every specimen, “dry or in spirit,” should have a number attached to it corresponding to a number in the collector’s notebook. The notebook should also contain information regarding the locale and the season in which the specimen was found, as well as its habits, habitat, and local name. The importance of a field notebook could not be overemphasized. The notebooks of Humboldt and Darwin were invaluable for their later work and the work of their fellow scientists. Meticulous records were essential for anyone hoping to make lasting contributions to science, whether in the physical sciences or natural history.32
The basic equipment of the collector included knives, scissors, scalpels, pliers, a large assortment of pins of various sizes, needles, a hammer, a small hatchet, cotton, paper, a folding net, a hoop net, a water net, forceps, a digger, glass phials, large and small packing cases, and a great number of pillboxes, all of which could be purchased from Stevens’s shop on Bloomsbury Street near the British Museum. Stevens also recommended having a good supply of arsenic soap, which was used as a pesticide to protect killed specimens against scavenging insects and putrefaction. Since the soap had to be made up in the field, he provided the recipe. Before 1750, salt and alum had been used to preserve bird and mammal skins, but after a few years skins thus “preserved” fell apart. In the 1750s, a Frenchman named Jean-Baptiste Becoeur invented arsenic soap, a milestone in the history of preservation and an advance responsible for the existence of vast modern bird and mammal collections.33 Although a small quantity may be absorbed through the skin, arsenic soap is not particularly toxic, which was fortunate for nineteenth-century naturalists since every specimen had to be washed thoroughly by hand.
In the field, freshly killed mammals and birds had to be treated within a few hours of death. Once putrefaction set in, the feathers of birds fell off. Before skinning an animal, its dimensions and the color of its eyes and soft parts had to be noted because, once dead, its colors faded quickly and shrinkage after skinning and preservation prevented accurate measurements of body size. Smaller mammals could be preserved in gin, or a “proof spirit” half diluted with water, after a slit was made in the underside. Larger mammals were skinned by making an incision in a straight line from the anus to the throat, with the skin then carefully detached with a knife. The skull and skeleton were left intact, but the eyes, brain, and tongue were scooped out and disposed of, as were the muscle tissue and internal organs. All adherent fat was scraped away; if any remained, the skin was strewn with powdered tan, made from willow or oak bark, or another potent astringent that dissolved fat without penetrating other tissues, before the application of the arsenic soap. The ears, lips, and feet of the larger mammals were doused with turpentine to accelerate drying and destroy potentially destructive insects. When completely dry, the skin was rolled up, hair innermost, beginning with the head. To prevent damage from abrasion, dried grass or moss was inserted during the rolling process. The skin had to be unrolled periodically and checked for moisture. If possible, it was further exposed to the sun and sprinkled once again with turpentine. If insects were detected, strong tobacco or, better, aromatic spices were added.34
Birds were treated in a similar fashion, but the incisions had to be as small as possible and in the least visible parts. Any blood was immediately wiped away to prevent staining of the plumage. A blunter instrument, like a wooden style, which was similar to a surgical probe, was preferable to a knife in separating the skin and feathers from the skeleton. The only bone left in place was the os coccyx (tailbone); without it, the tail feathers were likely to drop out. In the smaller birds, a fragment of the skull was cut away to extract the brain and eyes; in the larger birds, the brain and eyes were removed from the skull through multiple incisions in the back of the neck, the skin of which was then stitched back together. Stevens recommended that, if at all possible, a second specimen of the same species with its internal organs intact be preserved in spirits for the benefit of the taxonomist. His advice covered all faunal groups—insects, arachnids, crustaceans, sponges, starfish, land shells, freshwater and marine shells, reptiles, and fish—and was indispensable for Wallace and Bates.
The final hurdle that the two would-be explorers had to overcome was the acquisition of passports, which were dispensed by the Foreign Office only through an official recommendation. That recommendation came from Sir William Hooker, the curator of the Royal Botanic Gardens at Kew (and father of Darwin’s friend Joseph Hooker). Hooker was impressed with the enthusiasm and competence of the two young men, whom he had met during their visits to the conservatory and who had promised to do everything in their power to obtain interesting specimens for the museum and to communicate any information they thought worthwhile.35 Hooker wrote each man two recommendations—one for the Foreign Office and the other for the Brazilian authorities. The letter to the Brazilian authorities was meant to confirm their identities and facilitate their progress into the interior of the country.36
Wallace left London to spend a few days with the Bates family in Leicester, where he had a brief opportunity to practice shooting and skinning birds while he made last-minute preparations for his departure. From Leicester, he and Bates proceeded to Liverpool, stopping first at the greenhouses of Chatsworth, the quality of whose tropical collections rivaled that of Kew. Chatsworth also possessed the finest orchidarium in the world—the main attraction for Wallace, who had become enchanted with orchids ever since reading an article years earlier by John Lindley. Lindley, who described one species as “too delicate and beautiful for a flower of the earth,” gave orchids such a weird and mysterious charm that on the basis of these descriptions alone Wallace longed to go to the tropics, where some of the most exotic specimens flourished.37 On the evening of April 24, Wallace and Bates arrived at Liverpool harbor after a cold and miserable ride atop the stagecoach from Chatsworth. The next day, they called on a man who had collected butterflies in the Brazilian town of Pernambuco, near Pará, and who regaled them at dinner with stories of the country, the people, and the beauties of nature, as reflected in his impressive collections. The following morning, April 26, they were ready to board their ship, the merchant vessel Mischief, and sail for Brazil.38
A daguerreotype of Wallace, taken a few months before he sailed and published in his autobiography, depicts a rather severe-looking young man, seated with hands folded, dressed formally in a black suit and black ascot, his full head of hair parted on the right and swept sideways over the left ear. His clean-shaven face is not unhandsome; his intelligent eyes, with their penetrating gaze, are partly obscured by round, wire-rimmed glasses. Behind this faintly studious mien, however, was a steely strength. By the time of his departure, Wallace was well suited to the rigors of travel in one of the wildest unexplored regions on earth. With no firm commitments to anyone except his mother and sister, adapted to living in the most primitive accommodations of his own society, grounded in the sophisticated science of surveying and mapping, possessed of a foundation of knowledge astonishingly wide for a young man of his era who lacked a formal education, experienced as a botanist and beetle collector, imbued with the deistic and humanistic philosophies of Thomas Paine and Robert Owen, and inspired by the bold adventures and original discoveries of his idols Humboldt and Darwin, at the age of twenty-five Alfred Russel Wallace was ready to make his mark in the world. He had become accustomed to the life of a wanderer, and now he was embarking on a mission that was the stuff of many young men’s dreams. Here was the quintessential Victorian explorer—eccentric, independent, intrepid, brilliant, and already harboring the seeds of iconoclasm.