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Home , Alfred Newton, Alfred Russel Wallace, Charles Lyell, Charles Lyell (botanist), Ernst Dieffenbach, Flora Tasmaniae

On the Road to the Origin with Darwin, Hooker, and Gray

DUNCAN M. PORTER

Department of Virginia Polytechnic Institute and State University Blacksburg, Virginia 24061

INTRODUCTION

I began this paper intending to write a short essay with the title "Plant Geography in The Origin of ." However, I find that it has evolved into something quite different. Since the summer of 1989, when the original title was chosen, I have read some unpublished letters at the Royal Botanic Gardens, , and the Gray of that led me to substitute the present title. Much of the present paper now consists of excerpts from letters between (1809-1882), (1810-1888), and (1817-1911). They are relevant to my subject because Darwin depended upon Gray and Hooker, botanists respectively at Harvard and Kew, for much of the information on in the Origin. I intend to pursue that theme in a later publication. I do not apologize for these long excerpts, as I think that the story is best told in the words of the protagonists. Also, they show that Darwin was not operating in a vacuum. Letters of Asa Gray was published in 1893 (J. Gray 1893), and Life and Letters of Sir Joseph Dalton Hooker in 1918 (L. Huxley 1918). In spite of the large numbers of letters contained in these four volumes, many of the letters that I quote from have never been published. Apparently, they were not deemed of sufficient interest to the general audience that was presumed to comprise the readers of such collections. Before they are explored, however, we must see where Gray and Hooker fit in the path leading to the publica- tion of (C. Darwin 1859). (1825-1895) also enters our story, but more for what he is alleged to have done rather than for any early influence on Darwin. In spite of his son Leonard's statement that "Huxley was one of the few privileged to learn Darwin's argument before it was given to the world" (L. Huxley 1900:178),

Journal of the , vol. 26, no. 1 (Spring 1993), pp. 1-38. 1993 Kluwer Academic Publishers. Printed in the Netherlands. 2 DUNCAN M. PORTER

T. H. Huxley knew of Darwin's interest in the origin of species, but he did not know about as an explanation until publication of the Origin (Di Gregorio 1984). Table 1 outlines a paper trail that culminates in the publication of the Origin. There are some observations on phytogeography in Darwin's notebooks kept on the 1831-1836 voyage of H.M.S. Beagle (Porter 1987). Likewise, in his postvoyage transmutation notebooks of 1836-1844 (C. Darwin 1987), Darwin records queries and comments on plant distribution, mainly engendered by his copious reading. In spite of this, there is not much discussion of evidence from plant geography to bolster Darwin's evolutionary arguments in his 1842 sketch and 1844 essay (de Beer 1958). We now know that the latter was offered to for his comments in 1845, but that Hooker did not read Darwin's essay until 1847 (Burkhardt and Smith 1988:11). As we shall see, Hooker was aware of Darwin's evolutionary hypothesis by 1844, but Darwin did not confide in Gray until 1857. The only one of our other players documented to have read the 1844 essay was Huxley, but he did not do so until about 1887 (E Darwin 1887, 1:375).

Table 1. The path leading to the publication of On the Origin of Species

Beagle Notebooks (1831-1836) Transmutation Notebooks (1836-1844) Sketch of 1842 Essay of 1844 Natural Selection (1856-1858) Darwin-Wallace "joint paper" (1858) On the Origin of Species (1859)

Following Hooker's 1847 comments on the essay, Darwin's use of botanical evidence for his evolutionary ideas increased enor- mously, as can be seen in their copious correspondence (Burkhardt and Smith 1987, 1988, 1989, 1990, 1991). Indeed, by 1856-1858, when Darwin was working on his massive manuscript Natural Selection (C. Darwin 1975), Hooker had read and commented on several parts - most extensively on the last chapter, "Geographical Distribution." When Darwin received the fateful letter from in June 1858 that revealed Wallace's ideas about the mech- anism of evolutionary change, after more than twenty years of gathering data he finally was writing out his own ideas for publi- On the Road to the Origin with Darwin, Hooker, and Gray 3 cation. Hooker and Sir (1797-1875), Darwin's geological mentor, advised that the manuscript accompanying Wallace's letter be published immediately, along with proof that Darwin had formulated these ideas first. Thus was born the Darwin-Wallace "joint paper," presented to the Linnean Society of on , 1858, and published on August 30, 1858 (Darwin and Wallace 1858a). Part of the proffered proof that Darwin had priority in the matter was an abstract of an 1857 letter from Darwin to Gray, discussed below. The Origin, of course, was written as a result of Wallace's letter, Darwin first having tried and failed to produce thirty-page paper on his ideas for the Linnean Society. Darwin looked upon the Origin as an abstract of his "big book," Natural Selection.

EARLY STEPS TOWARD TRANSMUTATION

We now know that Hooker was not the only one with whom Darwin shared his evolutionary thoughts, nor was he the first (Table 2). Indeed, the first person who can be documented as knowing that Darwin was collecting information on the origin and variation of species was the Charles Lyell, at the time his closest confidant. On September 15, 1838, Darwin wrote:

I have lately been sadly tempted to be idle, that is as far as pure is concerned, by the delightful number of new views, which have been coming in, thickly & steadily, on the classification & affinities & instincts of - bearing on the question of species - note book, after note book has been filled, with facts, which begin to group themselves clearly under sublaws. (Burkhardt and Smith 1986:107)

On June 15, 1838, he had written to his second cousin (1805-1880), who had introduced Darwin to the joys of when they were students at , that

I am delighted to hear, you are such a good man, as not to have forgotten my questions about the crossing of animals. It is my prime hobby & I really think some day, I shall be able to do something on that most intricate subject species & varieties. (Burkhardt and Smith 1986:92)

However, this is a much less clear statement of his intentions than that to Lyell. A less ambiguous statement was sent to Fox in January 1841: 4 DUNCAN M. PORTER

Table 2. Darwin's associates and correspondents

Name Variation a Transmutationb

Charles Lyell 1838 1844? 1839 William Darwin Fox 1841 1856 George Robert Waterhouse 1843 1843? 1844 Joseph Dalton Hooker 1844 1844 Leonard Homer 1844 or 1845 Charles James Fox Bunbury 1845 1845 1847 Asa Gray 1855 1857 Hewett Cottrell Watson 1855? 1855? 1855 Charles Augustus Murray 1855 George Henry Kendrick Thwaites 1856 Syms Covington 1856 Thomas Henry Huxley 1856 John Lubbock 1856 1856 Laurence Edmondston 1856 Samuel Pickworth Woodward 1856 1856 1856 Frances Mackintosh Wedgwood 1856? Thomas Campbell Eyton 1856 1856 1856 1856 Hensleigh Wedgwood 1857 Alfred Russel Wallace 1857 1857 Jean Louis Armand de Quatrefages de Br6au 1858? Erasmus Alvey Darwin 1858 a Those who knew that Darwin was collecting information "on the origin and variation of species," and the documented dates that he introduced the subject to them. b Associates with whom Darwin shared his doubts on "species immutability," and the documented dates he first opened the subject. The dates have been determined primarily by information from Burkhardt and Smith (1986, 1987, 1988, 1989, 1990, 1991). On the Road to the Origin with Darwin, Hooker, and Gray 5

If you attend at all to Nat. His - I send you this P.S. as a memento, that I continue to collect all kinds of facts, about "Varieties & Species" for my some-day work to be so entitled

- the smallest contributions, thankfully accepted. (Burkhardt and Smith 1986:279)

In November 1839 Darwin wrote to his old Cambridge mentor John Stevens Henslow (1796-1861), Professor of , that

I keep on steadily collecting every sort of fact, which may throw light on the origin & variation of species (Burkhardt and Smith 1986:238)

This implies, but does not prove, that Henslow was aware of Darwin's interest in the subject before he received this letter. The others whom we now know to have been aware of Darwin's interest were the zoologist George Robert Waterhouse (1810-1888), who described the and some of the from the Beagle voyage, in 1843; Leonard Jenyns (1800-1893), author of the Beagle fishes and Henslow's brother- in-law, apparently in 1843; Joseph Dalton Hooker, botanist son of the director of the Royal Botanic Gardens, Kew, eventually to become Henslow's son-in-law, in 1844; Ernst Dieffenbach (1811-1855), a naturalist who in 1844 translated Darwin's Journal of Researches (C. Darwin 1839b) into German, in 1847; and Asa Gray, Fisher Professor of at Harvard University, not until 1855. From 1847 through 1854, Darwin's research and writing were almost entirely directed toward a systematic study of living and (1851a, 1851b, 1854, 1854-58). During these years, little time was available for him to pursue his species studies (hence the hiatus between Dieffenbach and Gray); however, when he returned to them in 1854 ("Sept. 9th. began sorting notes for Species Theory" [Burkhardt and Smith 1989:537]), he wrote not only to Gray, but also to several others for information on variation in various groups of organisms. Darwin's letters to Edgar Leopold Layard (1824-1900) and Charles Augustus Murray (1806-1895) that state his long interest in the variation and origin of species are extant. Layard, who served in the civil services of Ceylon and the Cape of Good Hope, studied their birds and mollusks; Murray, Minister Plenipotentiary to the Court of Persia, was approached for bird or skins. Darwin's letters to Edward Blyth (1810-1873), a zoologist who was Curator of the Asiatic Society of in Calcutta, and Hewett Cottrell Watson (1804-1881), an 6 DUNCAN M. PORTER

English botanist expert on the geographical distribution of the British flora, have not been found; however, their letters to Darwin indicate that they were apprised of his interest as well. Recent publication of Darwin's complete correspondence (Burkhardt and Smith 1985, 1986, 1987, 1988, 1989, 1990, 1991) once and for all dispels the myth that no one knew what Darwin was up to prior to publication of the Origin. After Darwin wrote to Gray of his interest in the origin of species, and before his and Wallace's "joint paper" was published in 1858, he also expressed this interest in the subject to the following: Syms Covington (1816?-1861), Darwin's servant on the Beagle and until 1839 when he emigrated to Australia, in 1856; Thomas Henry Huxley, Lecturer on Natural History in the and Naturalist to the Geological Survey, in 1856; John Lubbock (1834-1913), carcinologist and Darwin's neighbor, in 1856; and Thomas Vernon Wollaston (1822-1878), entomologist and con- chologist, in 1856. On April 30, 1856, Sir Charles Lyell wrote to Sir Charles Bunbury (see below): "When Huxley, Hooker, and Wollaston were at Darwin's last week they (all four of them) ran a tilt against species - further, I believe, than they are prepared to go" (T. Huxley 1887:550). Surely, transmutation was discussed at this meeting. However, in his recollections of the event some thirty years later, Huxley stated that he remembered nothing more than meeting Wollaston, with whom he says he may have argued because of the latter's conservative view of species. John Lubbock was also at this dinner with Darwin, Hooker, Huxley, and Wollaston (Darwin-Wallace Celebration 1908). Lubbock later wrote: "It is, however, only fair to remember that in Naturalists generally the new theory burst with startling abruptness like a 'bolt from the blue.' Lyell, Hooker, Huxley and I, on the contrary, had been in constant communication with Darwin, and had had time to consider and weigh the argument" (in ibid., p. 59). On April 6, 1859, Darwin wrote to Wallace in the that Huxley, while now believing in transmutation, perhaps was not yet converted to natural selection; on the other hand, "My neighbor & excellent naturalist J. Lubbock is enthusiastic convert" (Burkhardt and Smith 1991:279), indicating recent conversion. Wollaston never claimed to have knowledge of Darwin's views on the subject prior to the publication of the Origin. Variation was the topic of their overall conversation, and transmutation must have been a topic of discussion, but no one, least of all Darwin, admitted to a belief in transmutation. Others to whom Darwin is documented in his Correspondence On the Road to the Origin with Darwin, Hooker, and Gray 7 as having expressed an interest in the origin of species are Laurence Edmondston (1795-1879), Scottish physician and naturalist, in 1856; Samuel Pickworth Woodward (1821-1865), Assistant in the Department of Geology and of the British Museum, in 1856; John Edward Gray (1800-1875), Keeper of at the British Museum, in 1856; Frances Mackintosh Wedgwood (1800-1889), married to Hensleigh Wedgwood, Darwin's brother- in-law, in 1856(?); Thomas Campbell Eyton (1809-1880), naturalist and friend of Darwin while they were students at Cambridge, in 1856; Philip Henry Gosse (1810-1888), naturalist and writer, in 1856; James Dwight Dana (1813-1895), Professor of Geology at , in 1856; Hensleigh Wedgwood (1803-1891), philologist, Emma Darwin's brother, in 1857; Alfred Russel Wallace (1823-1913), natural history collector in the East Indies, in 1857; George Bentham (1800-1884), botanist who worked at Kew, in 1857; Jean Louis Armand de Quatrefages de Br6au (1810-1892), Professor of Natural History, Mus6um d', Paris, in 1858(?); and Erasmus Alvey Darwin (1804-1881), Charles's brother, trained as a physician, in 1858. Some, particularly family members, probably were aware of Darwin's interests before these documented dates. Obviously, there was a burst of correspondence seeking information on variation upon Darwin's completion of his studies. The first to be made aware of Darwin's belief in the transmu- tation of species was Joseph Hooker, in the often-quoted passage from a letter written January 11, 1844: "At last gleams of light have come, & I am almost convinced (quite contrary to opinion I started with) that species are not (it is like confessing a murder) immutable" (Burkhardt and Smith 1987:2). Darwin and Hooker had known each other well for only two months, but they had taken an immediate liking to one another. Darwin turned now to Hooker, more than anyone previously, as a sounding board for his ideas. The others to whom Darwin confessed his belief in species muta- bility were Leonard Jenyns in 1844 and Charles Lyell, apparently also in 1844; Leonard Homer (1785-1864), President of the Geological Society and Lyell's father-in-law, in 1844 or 1845; Charles James Fox Bunbury (1809-1886), a botanist married to Lyell's sister-in-law, in 1845; Richard Owen (1804-1892), Hunterian Professor at the Royal College of Surgeons, who described the fossil mammals of the Beagle voyage, in 1845; George Henry Kendrick Thwaites (1811-1882), Superintendent of the Botanic Gardens, Peradeniya, Ceylon, in 1856; Samuel Pickworth Woodward, William Darwin Fox, and James Dwight Dana, in 1856; and Asa Gray in 1857. All appeared receptive at 8 DUNCAN M. PORTER the time, save Owen, who fifteen years later also opposed these ideas in print. Darwin wrote to Hooker on September 10, 1845: "I was, however, pleased to hear from Owen (who is vehemently opposed to any mutability in species) that he thought it was a very fair subject & that there was a mass of facts to be brought to on the question, not hitherto collected" (Burkhardt and Smith 1987:153). It was probably Owen's vehement opposition, however, that convinced Darwin to gather more information in favor of trans- mutation before he was willing to share his ideas in a wider context. Except for Owen, Woodward, and Gray, there were not only intellectual ties among those whom Darwin approached, but family ties as well. The only ones with whom Darwin discussed the mech- anism of transmutation (natural selection) were Hooker, Lye11, and Gray. David L. Hull (1985) makes the point that those with whom Darwin discussed these subjects were chosen for the constructive criticism they could provide him.

GRAY, THE HOOKERS, AND DARWIN

In 1835, Asa Gray was working as an assistant to John Torrey (1796-1873), botanist and Professor of at New York City's College of Physicians and Surgeons. Gray began a corre- spondence that was to last for thirty years by writing to Torrey's friend (1785-1865), Regius Professor of Botany at Glasgow University, concerning North American sedges. Hooker had many North American specimens in his herbarium, gathered by his field collectors, and was publishing his Flora Boreali-Americana (1829-40). Gray sent manuscript and sought advice; Hooker was impressed with Torrey's prot6g6 and encour- aged his research. By 1838, Gray had been hired by the fledgling University of Michigan to be its first professor. His first duty was to make a trip to Europe in order to purchase books and scientific equip- ment for the university - this was the official reason for the trip, but it would also give Gray a superb opportunity to visit British and European herbaria in order to gather data for his and Torrey's Flora of (Torrey and Gray 1838-43). He took advantage of the opportunity by first traveling to Glasgow to see Sir William Hooker, who had been knighted in 1836. Gray arrived in December 1838 and spent three weeks working on North American plants in Sir William's herbarium. He also made the acquaintance of Sir William's son Joseph, who was working to qualify as a surgeon. Joseph Hooker anticipated becoming assistant surgeon and botanist On the Road to the Origin with Darwin, Hooker, and Gray 9 on a voyage to search for the Southern Magnetic Pole with Captain . Following visits to Kinross, Edinburgh, and Durham, Gray arrived in London on January 16, 1839, to examine North American plant collections in the herbarium of the British Museum. There he met the formidable Robert Brown (1773-1858), Keeper of the Banksian Herbarium and Secretary of the Linnean Society. More importantly, he there found Sir William and Joseph Hooker, who had come to London on a two-week trip of their own. The three botanists together visited the Royal Gardens at Kew. During these two weeks, Gray and Joseph Hooker spent a great deal of time together, cementing a friendship that would prove just as strong as the later one of Hooker and Darwin. Another botanist whom Gray met was George Bentham, the nephew and heir of the utilitarian philosopher and economist . As with Sir William Hooker, Gray maintained a regular correspondence with Bentham. He began this correspondence by addressing Bentham as "My dear friend." On January 22, 1839, Gray entered the following in his diary:

This morning we [Gray and the Hookers] breakfasted with Richard Taylor [ 1781-1858; editor of Annals of Natural History] in the City; and went afterwards to the College of Surgeons, by appointment [Sir William] Hooker had made, to see Professor Owen, and the fine museum of the college under his charge ('s originally); a magnificent collection it is, in the finest possible order; and the arrangement and plan of the rooms is far, very far better and prettier than any I have seen. I shall make some memoranda about it. We there met Mr. Darwin, the natu- ralist who accompanied Captain King in the Beagle) I was glad to form the acquaintance of such a profound scientific scholar as Professor Owen [!] - the best comparative anatomist living, still young, and one of the most mild, gentle, childlike men I ever saw. He gave us a great deal of most interesting informa- tion, and showed us personally throughout the whole museum. (J. Gray 1893, 1:117)

In later life, apparently neither Gray nor Joseph Hooker remem- bered this encounter with Darwin, Hooker referring to a later one in 1839 in Trafalgar Square (F. Darwin 1887, 1:380), and Gray to a meeting in 1851 discussed below.

1. Philip Parker King (1793-1856) was captain of H.M.S. Beagle on its 1826-30 voyage; the captain on Darwin's 1831-36 voyage was Robert FitzRoy (1805-1865). 10 DUNCAN M. PORTER

Upon Gray's return to the in November 1839 he began his extensive correspondence with Bentham, and he con- tinued his letters to Sir William. In September, Joseph Hooker had left on H.M.S. Erebus to collect extensively in the Southern Hemisphere; he would return four years later, in September 1843. Sir William left Glasgow in April 1841 to become the first Director of the Royal Botanic Gardens, Kew. In 1842, Gray became Fisher Professor of Natural History at Harvard, and Darwin moved from London to Down. Although Darwin and Hooker did not exchange letters during this time, they remained aware of one another. On December 6, 1842, Joseph wrote to his mother: "Clouds and fogs, rain and snow justified all Darwin's accurate descriptions of a dreary Fuegian summer. Indeed all Darwin's remarks are so true and so graphic wherever we go that Mr. Lyell's kind present is not only indispensable but a delightful companion and guide" (L. Huxley 1918, 1:136). Darwin's Journal andRemarks (1839a) was published in August 1839 (Freeman 1977), just before Hooker sailed on his own voyage. However, he had earlier been provided with copies of proof sheets of the book by the botanist Charles Lyell, St. (1769-1849), Darwin having sent them to Charles, Jr. Late in life, Hooker wrote to , his father's biographer:

At this time I was hurrying on my studies, so as to take my degree before volunteering to accompany Sir James Ross in the Expedition, which had just been determined on by the Admiralty; and so pressed for time was I, that I used to sleep with the sheets of the "Journal" under my pillow, that I might read them between waking and rising. They impressed me profoundly, I might say disparagingly, with the variety of acquirements, mental and physical, required in a naturalist who should follow in Darwin's footsteps, whilst they stimulated me to enthusiasm in the desire to travel and observe. (F. Darwin 1887, 1:381)

On his part, Darwin wrote to Sir William on March 12, 1843, asking to be remembered to Joseph when he next wrote and urging Sir William to push Joseph to publish his journal and an . Darwin promised that his plant collections from the Beagle voyage would be made available for Joseph by Henslow, to whom the specimens were sent. Darwin wrote his first letter to Joseph Hooker, concerning the identification of his Beagle plant collections, in November 1843. Hooker responded the same month, and so began another voluminous correspondence. On the Road to the Origin with Darwin, Hooker, and Gray 11

Joseph Hooker soon (January 16, 1844) wrote his first letter to Gray, who answered on March 1. Thus began their long, intimate correspondence, full of botany and gossip. Gray's letters to and from Bentham and Sir William remained almost entirely botan- ical, with little indication of personal intimacy. Hooker began his first letter to Gray:

I have never had the pleasure of addressing you either by word of mouth, or by letter, for now exactly 5 years; you must not however think that the silence has arisen on my part from forgetfulness of our former friendship, which has ["ever" deleted] been much cherished in my mind ever since it was first formed. (Archives, Gray Herbarium Library)

Gray answered:

I was very much gratified at receiving your kind letter of January 16; and I was quite startled at the lapse of time, I assure you, when you reminded me that five years had elapsed since we were running about the streets of London together. Since that time you have seen the world, indeed, or some very out-of-the-way parts of it; and you now stand in a perfectly unrivaled position as a botanist, as to advantages, etc., with the finest collections and libraries of the world within your reach; and if you do not accom- plish something worth the while, you ought not to bear the name of Hooker. (J. Gray 1893, 1:317)

Although they resumed their friendship through the post, Gray and Hooker exchanged only a few letters over the next several years. In November 1847, Hooker once again set sail from , this time to botanize in , , , and . He returned to England in March 1851, apparently not having exchanged letters with Gray since 1846. Joseph Hooker's Himalayan Journals (1854) were dedicated to his good friend Charles Darwin. On February 20, 1854, Darwin wrote to Henslow: "Have you seen Hooker's book yet: it is most beautifully got up & illustrated, & I feel greatly honoured & very much gratified at the wonderful compliment of its dedication to me" (Burkhardt and Smith 1989:176). Meanwhile, in June 1850, Gray made his second trip to Britain and Europe to visit botanists and herbaria. This led to the second meeting of Gray, Hooker, and Darwin. Gray had married Miss Jane Loring of in 1848, and she accompanied him to England. In her biography of her husband, Mrs. Gray wrote that 12 DUNCAN M. PORTER

sometime between late March and mid-April 1851, following a trip to and Cambridge,

On returning to Kew, Dr. Gray found Dr. Joseph Hooker, just back from his journey to the and Thibet. Dr. Thompson 2 was also there, just home from India, where he had been imprisoned with Lady Sale and others, twenty of them in one small room, during the trouble in Afghanistan. And one day came an invitation to lunch from the Hookers', "to meet Mr. Darwin, who is coming to meet Dr. Hooker; is distinguished as a naturalist." "Mr. Darwin was a lively, agreeable person" [Mrs. Gray's journal]. (J. Gray 1893, 1:380; brackets in original)

Following the Grays' return to Harvard in August 1851, the name "Darwin" begins to appear with some frequency in the letters between Gray and Hooker. The frequency of the letters between them also rapidly quickens. One of the results of Hooker's voyage on the Erebus was a flora of (J. Hooker 1853-55). In September 1853, Hooker wrote to Col. William Munro (1818-1880), an expert on grasses, that he was "travailing through an Essay on 'Species, their distribution and variation,' for the New Zealand Flora Introduction" (L. Huxley 1918, 1:469). On September 21, Hooker wrote to Gray regarding this essay:

The New Zealand Flora is ( I have just written for the preface) the most difficult in the world, hosts of obscure Nat. Ords. [Natural Orders: i.e., botanical families] genera & species, dirty dioecious green black brown fleshy flowers; & Nat. Ords. of single or few rare genera & that are not to be found out ["by" deleted] without both flower & fruit. Upwards of 90 Nat. Ords. to be known to make out every 8 plants!, & nothing natural about any of them. My work I am sure abounds in error, I have just written such a longwinded Essay to precede it upon variation distribution & origin of species. Not that I have anything new to propose or any dogma or theory to support, but I think it high time for Systematists to take some decided stand upon such grounds; if every noodle that knows a cabbage from a Cabbage Palm is to set up as a describer of new species from every comer of [the] globe because he finds a difference in his specimens then [this] is an end of Systematic Botany. I think the time is come

2. Thomas Thomson (1817-1878) was Director of the Calcutta Botanic Garden and botanical collaborator with Hooker on the flora of India. On the Road to the Origin with Darwin, Hooker, and Gray 13

when no man's word should be taken for a species except it be known that he has consulted large Herbaria & books. (Archives, Gray Herbarium Library)

This excerpt gives the reader a good idea of the tenor of their correspondence and also introduces the origin of species to it. This was perhaps a bold move on Hooker's part, for in an 1846 review Gray had "left no doubt that he considered the idea of the instead of special creation most objec- tionable both theologically and philosophically" (Dupree 1959:145-146). On September 25, 1853, Darwin wrote to Hooker: "I read your paper with great interest. It seems all very clear; & will form an admirable introduction to the N.Z. Flora, or to any Flora in the world .... The whole will be very useful to me, whenever I under- take my volume [i.e., Natural Selection]" (Burkhardt and Smith 1989:155). Darwin was particularly interested in Hooker's infor- mation on variation and geographical distribution of plant species. The "Introductory Essay" to the Flora Novae-Zelandiae was pub- lished on December 6, 1853 (Turrill 1953). In it, Hooker discussed the history of botanical in New Zealand; the limits, ranges, and variation of species in the flora; and the flora's com- position and relationships. In his discussion of species, Hooker states four theoretical principles that reveal his own feelings at the time on their origins, variation, and distribution:

1. That all the individuals of a species (as I attempt to confine the term) have proceeded from one parent (or pair), and that they retain their distinctive (specific) characters. 2. That species vary more than is generally admitted to be the case. 3. That they are also much more widely distributed than is usually supposed. 4. That their distribution has been effected by natural causes; but that these are not necessarily the same as those to which they are now exposed. (J. Hooker 1853-55, /:viii)

Only Darwin could appreciate how far Hooker had come around to accepting his evolutionary ideas. Gray was soon sent a copy of the Essay, and on February 23, 1854, he wrote to Sir William: "I am charmed with Dr. Hooker's Introductory Essay to F1. N. Zealand. I have abstracted a large part of it for Silliman's Journal [American Journal of and Arts] - so much indeed that I fear it cannot find room before the 14 DUNCAN M. PORTER

May no. of that Journal" (Royal Botanic Gardens, Kew, N. American Letters/1851-58/LXIV, p. 220v). Indeed, the "Notice of Dr. Hooker's Flora of New Zealand" was so lengthy that it continued in two numbers of the American Journal of Science (A. Gray 1854). It seems likely that the Essay was sent by Hooker to Gray as soon as it appeared. However, a letter of December 7, 1853, from Hooker to Gray does not mention it. The first letter I have found that discusses the Essay is one written on January 26, 1854, from Hooker to Gray. It addresses comments made by Gray on the Essay, in a letter that apparently is no longer extant. Hooker wrote:

I was extremely pleased by your letter last night, and quite as much with the mere fact of my treating of the subject having been thought worthy [of] our attention, as with the many too flattering things you say of it. Such Essays attract so little atten- tion in this country, that one feels, at least I did, that I was writing for the dead more than for the living, though amongst other men Agassiz had a prominent seat in judgement before me. (L. Huxley 1918, 1:473)

The Swiss-born Jean Louis Rodolphe Agassiz (1807-1873), who in 1847 was appointed Professor of Natural History at Harvard University, was a leading advocate of the multiple creations of species. Agassiz was also Gray's premier scientific rival at Harvard; he was soon to become the most outspoken anti-Darwinian in the United States (Dupree 1959; Lurie 1960). Hooker continued:

After all I regard the whole Essay more a rrsum6 of general impressions than a specimen of close reasoning, for of the latter, in truth, the subject does not admit. There is not a single argument that will not cut both ways, and may not be turned pro and con species, specific centres, &c., &c. Your turning my arguments against myself on the point, that two originally created distinct species so similar as to be almost undistin- guishable, may exist in two widely sundered localities, is an awful staggerer, and I have always felt it to be the most imprac- ticable objection of any to the possibility of determining what is and what is not species. (473)

These are the kinds of comments that Hooker and Darwin had been exchanging for the past decade. Hooker stated to Gray:

I combat this theory more upon principle than upon facts; - once On the Road to the Origin with Darwin, Hooker, and Gray 15

admit it and the flood gates are opened to species-mongers, and it is cast in your teeth every moment, as an argument for making every slight difference, if only accompanied with geo- graphical segregation, of specific value. (473-474)

Hooker's strong belief in the single origin of species was firmly based on his many years of personal observations on the varia- tion and distribution of species in the field. He continued:

Nevertheless I am quite aware that such species must exist; I do not deny, nor would I blink [avoid or flinch from], the evidence in favour of it, nor that it is the gravest of all objec- tions to the pronouncement upon species in our present state of knowledge. I therefore admit its application to practice only in exceptional cases. The long and short of it is, that if you admit two centres you may as well admit all Agassiz, you cannot draw the line, and Geographical distribution is hence a vain study, the connection of life with the revolutions of our globe and with all the physics of is naught, and nothing can come of its pursuit but the temporary gratification of taste and ingenuity. (474)

Gray answered Hooker in a letter of February 21, 1854. Except for a few lines published by A. Hunter Dupree (1959:234-235), it is hitherto unpublished. Gray began:

I take it as a great compliment that so busy a man as you are should find time, and be disposed, to write me such long and interesting letters as yours of Jany. 2nd [actually January 25]. The whole subject is one of the highest interest, the very highest, but yet one, as you justly observe, "not admitting of close reasoning" - or rather, upon which our reasoning on the data can bring us only to more or less probable conclusions. It is there- fore very easy to criti[ci]ze the conclusions of others on these points, the moment they lay down general propositions, and that is all I can pretend to do. I have not the right to form them, which you have. But I am gratified to find, more and more, that my general notions, formed in the closet, are so well con- firmed by one who has "seen the world" like yourself. (Royal Botanic Gardens, Kew Correspondence/Asa Gray/1839-1873, p. 103)

That is, Gray was a "closet botanist," one who studies plant 16 DUNCAN M. PORTER specimens collected by others and who has little field experience with them. He continued:

Not blind to the difficulties of the position, we maintain the orthodox faith, in the midst of "right-hand defections and left hand falling away." In respect to the points in which I seem to have contradicted myself, or you, probably my hurried letter, which I did not look over, may not have clearly expressed what I was driving at. There is no point upon which we seem to differ that I hold with any tenacity or prejudice, ["such that" deleted] except as they seem to be mostly fair inferences from your own premises; - so that I am a good subject for you to ply with facts and arguments. - For example, you seem to think that representative species, i.e. closely resembling species belonging to separated areas, are not to be admitted otherwise than as an exception to the general rule, - an exception that is much in your way. Now, it seems to me, that if species were originally given each to a circumscribed and [illegible word deleted] local area (which you maintain, even in the strictest form); - if species were created with almost infinitely various degrees of resemblance among each other (which is just what scientific Systematic Botany rests upon), and if it be true that congeneric forms are often found in two widely separated areas of similar climate (as in the U.S. & , Arctic & Antarctic regions &c. &c.), then the occurrence of two closely resembling, ["species" deleted] yet originally distinct species in widely separated places of similar climate is just what I should apriori expect. Is it not just what you should maintain so long as you deny the double origin of species? - requiring, however, always that specific marks should be shown, as evidence that the two are different. But who shall lay down a rule as to how much two plants shall differ in order to be admitted as specifically different? That must be determined by observation and experience alone; - which show, that while some species are extremely polymorphous, others, that we doubt not are distinct, differ constantly in one or two particulars which experience proves to be of no moment at all in analogous cases. (If it be said that it is not likely the Creator should originate two species with so trifling a difference between them, I would suggest that the marks we define a species by do not consti- tute the species; they are only the convenient "outward and visible sign of an inward grace." (103-103v)

A staunch Congregationalist, Gray occasionally used such religious On the Road to the Origin with Darwin, Hooker, and Gray 17 rhetoric in his correspondence. He was to become the chief avowedly Christian spokesman for Darwin in America. Following a short discussion of crowberry distribution, his letter to Hooker continued:

When we find two such representative forms geographically connected by intermediate stations - the differences, such as they are, still holding good - then whether they are still to be regarded as distinct in origin, but each spread till their limits meet, or as varieties of one species of which perhaps the original type has disappeared, is a question to be decided either way, with more or less probability, according to our best judgement on the case, but we cannot pretend to decide it with anything like certainty. But if, with the mingling or approximation of the areas we find a shading off of the differences, then it is far most likely that they all belong to one species, and practically we should so consider them. - even if say the Antarctic specimens constantly differed from the Arctic - for the universal law that the offspring strongly tends to resemble the parent in all respects will sufficiently account for the uniformity of the Antarctic state; while, on the other hand, the perpetuation of that form ["while" deleted] so long as subjected to only the same external condi- tions and isolated from its fellows, is no proof that this form is itself a species. (Though if it constantly held its own while growing commingled with the related forms, I should infer the contrary). And this leads me to two points that I must have boggled in my former letter: for as they stand in my mind, I see no real contradiction between them, viz. the general and fundamental law of genetic resemblance, and the exceptional, inexplicable (we should call it impossible antecedent to the fact) origin of races, which, once originated, equally follow the law of genetic resemblance, or show the strongest tendency to reproduce the parental features or peculiarities, - though this be partly over- borne by the tendency to revert to the original type, - but more generally obliterated by intermixture of stock .... The arrange- ments of nature go to prevent the perpetuation of varieties & races. Interfere with Nature, by domestication & segregation, and they spring up as fast as you please. (103v-104).

So Gray, the closet botanist, and Hooker, the field botanist, were struggling with the origin and perpetuation of races, varieties, and species of plants. Both still professed that species were divinely created, but their views were evolving. 18 DUNCAN M. PORTER

On March 24, 1854, Hooker responded:

Very many thanks for your capital long letter, which begins by agreeing with me that, "the subject does not admit of close reasoning"; and goes on with as pretty a specimen of admirable close, clear, and accurate reasoning as I ever wish to peruse. I only wish you had taken up the subject instead of me, for you throw out your grapnals with a judgement and precision that put my loose ratiocination (is that the word?) to shame. (L. Huxley 1918, 1:476)

Unknown to Gray, Hooker was so impressed with the former's ratiocinations, that he forwarded the letter to Darwin, who responded:

I am particularly obliged to you for sending me Asa Gray's letter; how very pleasantly he writes .... I was pleased & surprised to see A Gray's remarks on crossing, obliterating varieties, on which, as you know, I have been collecting facts for these dozen years. (Burkhardt and Smith 1989:186, 187)

One would think that Darwin, recognizing Gray's keen interest in a subject on which he had spent so much thought since the mid-1830s, would have immediately written Gray and begun asking him for information on variation and geographical distribution, as he had done with Hooker a decade before. However, he did not do so, presumably because during most of 1854 he was immersed in writing and reading proof for his barnacle studies, not returning to his "Species Theory" until September (see above). Meanwhile, Hooker and Gray kept up their regular correspondence. Hooker wrote on November 1, 1854: "I have been staying three days with Darwin, who asks how it is that no American has ever written a popular or scientific work on the general characters of American vegetation as compared with European; is it so?" (Archives, Gray Herbarium Library). During this month, Darwin "was re-examining the geographical distribution of plants on a worldwide scale" (Burkhardt and Smith 1989:239). On the 21st, Gray responded: "The work Darwin suggests would be most interesting & useful. I wish there were some fit person on this side of the water to undertake it" (Royal Botanic Gardens, Kew Correspondence/Asa Gray/1839-1873, p. l15v). On the 30th of November, Hooker was awarded the of the Royal Society for his botanical researches on the Antarctic and Indian expeditions. In presenting the Royal Medal, William On the Road to the Origin with Darwin, Hooker, and Gray 19

Parsons, Lord Rosse, President of the Royal Society, stated that it was awarded in part for Hooker's work on "one of the most difficult questions of natural science, which is now acquiring that prominence to which it is so well entitled, - I mean the question of the origin and distribution of species" (Parsons 1855:261). Study of the origin of species had become mainline science; Darwin was not working in a vacuum. He was back working on the species question and already had solicited information from Edward Blyth and Hewett C. Watson.

DARWIN RETURNS TO THE SPECIES QUESTION

By April 13, 1855, Darwin wrote to Hooker that he had made a list of the naturalized plants in Gray's Manual of the Botany of the Northern United States (A. Gray 1848). He was "thinking of writing with many apologies to A. Gray to ask him a few questions on alpine plants &c." (Burkhardt and Smith 1989:306). Charles Darwin's first letter to Asa Gray was penned on April 25, 1855. It began:

I hope that you will remember that I had the pleasure of being introduced to you at Kew [in 1851, not 1839]. I want to beg a great favour of you, for which I well know I can offer no apology. But the favour will not, I think, cause you much trouble & will greatly oblige me. As I am no Botanist, it will seem so absurd to you my asking botanical questions, that I may premise that I have for several years been collecting facts on "Variation," & when I find that any general remarks seems to hold good amongst animals, I try to test it in Plants. (Burkhardt and Smith 1989:322)

Darwin enclosed a list of alpine species compiled from Gray's book and asked him to indicate habitats and ranges of those plants on the list. He ended his letter:

I venture to ask for one more piece of information, viz. whether you have anywhere published a list of the phanerogamic species common to Europe, as has been done with the shells & Birds, so that a non-Botanist may judge a little on the relationship of the two floras. Such a list would be of extreme interest for me in several points of view & I should think for others. I suppose there would not be more than a few hundred out of the 2004 species in your Manual. Should you think it very presumptuous in me to suggest to you to publish (if not already done) such a 20 DUNCAN M. PORTER

list in some journal? - I would do it for myself, but I sh a. assuredly fall into many blunders. I can assure you, that I perceive bow presumptuous it is in me, not a Botanist, to make even the most trifling suggestion to such a Botanist as yourself; but from what I saw & have heard of you from our dear & kind friend Hooker, I hope & think that you will forgive me, & believe me, with much respect, IDear Sirl Your's very faithfully I Charles Darwin. (323)

This was the stimulus for G-ray's papers on "Statistics of the Flora of the Northern United States" (A. Gray 1856, 1857), which Darwin put to good use in Natural Selection and the Origin. Following a chatty letter from Hooker that praised his work, Gray responded on May 22, 1855:

Your letter of the 28th inst. [April 28] does please me not a little. It reached me only yesterday, and at a crowded time, and it is as much as I can do to get off the present package by tomorrow's steamer from Boston. It contains - open for you to look over, if you like, a reply to a letter lately received from your good friend Darwin, sending back a list he sent me for the blanks to be filled up - about the distribution of the few alpine plants we have in Northern U.S. proper. (Royal Botanic Gardens, Kew Correspondence/Asa Gray/1839-1873, p. 117)

It was more efficient (and probably cheaper) to send more than one letter in the same envelope, and it became common in what was now a three-sided correspondence. Gray began his first letter to Darwin:

I remember with much pleasure the opportunity I enjoyed of making your acquaintance at Hooker's three years ago; and besides that should always be most glad if I could in any small degree furnish materials for your interesting investigations. And these related to matters in which I take much interest, but can do no more than to furnish some few data when asked for, that others, who happily have leisure for such inquiries, may work up. (Burkhardt and Smith 1989:334)

It can be seen from this letter and his second to Darwin (quoted in part below) that Gray, who was at the time inundated with work at Harvard, was able to send data but not to spend time in theo- rizing. Indeed, during his long career, Gray published a great deal, but most of his work was descriptive rather than theoretical. On the Road to the Origin with Darwin, Hooker, and Gray 21

Hooker wrote to Gray on the 4th of June: "I read your letter to Darwin which I think will please him much" (Archives, Gray Herbarium Library). Indeed, Darwin wrote Hooker on the 5th: "What a remarkably nice & kind letter Dr. A. Gray has sent me in answer to my troublesome queries" (Burkhardt and Smith 1989:342); and on the 10th, "How pleasantly Gray takes my request, & I think I shall have done a good turn if I make him write a paper on Geograph. Distrib. of plants of U. States" (Burkhardt and Smith 1989:350). In Gray, Darwin had found another botanist almost as helpful as Hooker. An added advantage was Gray's knowledge of the plants of North America and Japan, floras poorly known by Hooker. In his second letter to Gray, on June 8, Darwin wrote:

I thank you cordially for your remarkably kind letter of the 22d ulto. [ultimo, of last month] & for the extremely pleasant & obliging manner in which you have taken my rather troublesome questions .... You ask me to state definitely some of the points on which I much wish for information; but I really hardly can, for they are so vague, & I rather wish to see what results will come out from comparisons, than have as yet defined objects .... There is one point, on which I am most anxious for infor- mation; & I mention it with the greatest hesitation, & only in the full belief that you will believe me that I have not the folly & presumption to hope for a second that you will give it, without you can with very little trouble. The point can at present interest no one but myself, which makes the case wholly different from geographical Distribution. The only way in which, I think, you possibly could do it with little trouble, w d. be to bear in mind, whilst correcting your Proof-Sheets of the Manual, my question, & put a cross or mark to the species, & whenever sending a parcel to Hooker to let me have such old sheets. But this w d. give you the trouble of remembering my question, & I can hardly hope or expect that you will do it. - But I will just mention what I want, it is, to have marked the "close species" in a Flora, so as to compare in different Floras whether the same genera have "close species", & for other purposes too vague to enumerate. - I have attempted by Hooker's help to ascertain in a similar way whether the different species of same genera in distant quarters of the Globe are variable or present vari- eties. The definition I should give of a "close species" was one that you thought specifically distinct, but which you could conceive that some other good Botanist might think only a race 22 DUNCAN M. PORTER

or variety; - or again a species that you had trouble, though having opportunities of knowing it well, in discriminating from some other species. Supposing that you were inclined to be so very kind as to do this, & could (which I do not expect) spare the time, as I have said, a mere cross to each such species in any useless proof-sheets, would give me the information desired, which I may add, I know must be vague. (Burkhardt and Smith 1989:346, 347, 348-349)

Besides Gray and Hooker, Henslow and Watson also were queried about "close species" in a flora. Interestingly, Henslow and Watson were asked independently by Darwin to mark the "close species" in The London Catalogue of British Plants (Watson and Syme 1853). Presumably, Henslow was used as a check to make sure that Watson was not a "species-splitter." Their tallies were quite close. In his search for evidence of transmutation, Darwin speculated that large genera should have more closely related species ("close species") and varieties than small genera - that is, they should show more variation. The data he received from Gray and Watson on the plants of the Northern United States and Britain confirmed his conjecture. This information was used in both Natural Selection and the Origin. Gray's second letter to Darwin was dated June 30, 1855. He began with another denial that he was a theoretician:

Your long letter of the 8th inst. is full of interest to me, and I shall follow out your hints as far as I can. I rejoice in furnishing facts to others to work up in their bearing on general ques- tions, and feel it the more my duty to do so in as much as, from preoccupation of mind & time & want of experience, I am unable to contribute direct original investigations of the sort to the advancement of science. Your request at the close of your letter, which you have such needless hesitation in making, is just the sort of one which is easy for me to reply to, as it lies directly in my way. It would probably pass out of my mind, however, at the time you propose,

- so I will attend to it at once, to fill up the intervals of time left me while attending to one or two pupils. - So I take some unbound sheets of a copy of the Manual, and mark off the "close species", by connecting them with a bracket (Those thus connected some of them I should in revision unite under one - many more D r. Hooker would unite route suite, and for the rest it would not be extraordinary if, in any case, the discovery of On the Road to the Origin with Darwin, Hooker, and Gray 23

intermediate forms compelled their union. (Burkhardt and Smith 1989:362)

Hooker was well known as a lumper of species, not a splitter. Toward the end of his letter, Gray added:

I should like to write an essay on species, some day; but before I should have time to do it, in my plodding way, I hope you, or Hooker will do it, and much better far. I am most glad to be in conference with Hooker & yourself, on these matters, and I think we may, or rather you may, in a few years settle the question as to whether Agassiz's - or Hooker's views are correct; they are certainly widely different. (363)

Agassiz believed in multiple creations of a species - that is, that it could be created more than once in different places. Hooker believed that a species was created only once. Gray in fact had at least begun an essay on species in his letter to Hooker of February 21, 1854, which Hooker shared with Darwin, and which led to Darwin's first writing Gray. Darwin responded on July 21, 1855: "Your discussion on con- necting & separating forms seems to me so philosophical, that I much hope that someday you will be as good as your word & write an "Essay on Species" (Burkhardt and Smith 1989:384). Gray never published such an essay, but he did discuss his own species concept when reviewing the Origin (A, Gray 1860). While the correspondence with Gray was taking place, Darwin and Hooker were discussing species creation with less restraint than they did with Gray. Hooker wrote between June 5 and June 10, 1855:

After all it is very easy to talk of the creation of a species in the Lyellian view of creation3 but the idea is no more tangible than that of the Trinity & to be really firmly & implicitly believed is neither more nor less than a superstition - a believing in what the human mind cannot grasp. It is much easier to believe with you in transmutation, until you work back to the vital spark - avis creatrix [creative force] or whatever you may call it; which is a fact as inscrutable as a full blown species. (Burkhardt and Smith 1989:345)

3. Sir Charles Lyell believed that new species were created to replace those becoming extinct because of changes in their environments. 24 DUNCAN M. PORTER

Darwin answered on June 10:

What you say about no one realising creation strikes me as very true; but I think & hope that there is nearly as much difference between trying to find out whether species of a genus have had a common ancestor & concerning oneself with the first origin of life, as between making out the laws of chemical attraction & the first origin of matter. (350)

So Darwin recognized that the origin of species and the origin of life are two separate questions, a discrimination that many critics of today still fail to realize. Hooker was very much in sympathy with Darwin's views, more so than has hitherto been recognized. Following a discussion of Australian legumes and Indian composites, he responded on July 8:

These facts 4 shake species to their foundation - but according to my view of species, as contrasted with other systematists, there are sore few of them. In fact if there were a possibility of bringing your & my opinions to book, it might prove that we were not so far divided. The more I study the more vague my conception of a species grows, & I have given up caring whether they are all pups of one generic type or not - that the main forms remain so long distinct, that we may through their characters, trace their distribution, is certainly all we can expect to prove in our day; & the laws of that distribution more than we shall establish in our lifetime (Burkhardt and Smith 1989:372)

Meanwhile, Hooker and Gray, and Gray and Darwin, continued to correspond, although there were many more letters between the former. Most of the correspondence had to do with distributional matters. On October 15, 1856, Hooker wrote to Gray: "Darwin was here yesterday much pleased with your Essay & is writing to you on the subject of its continuation" (Archives, Gray Herbarium Library). The "Essay" was the first instalment of "Statistics of the Flora of the Northern United States" (A. Gray 1856). Hooker added on February 20, 1857:"1000 thanks for your excellent letter, & for the continuation of the "Distrib. of N.U.S. plants" [A. Gray 1857:62-84] which Darwin is delighted with" (Archives, Gray Herbarium Library). Besides this, Hooker kept dropping hints to Gray about transmutation. For example, on July 16, 1856, in a discussion of

4. On the aforementioned legumes and composites. On the Road to the Origin with Darwin, Hooker, and Gray 25 the Arctic flora, he wrote: "On the other hand may the said species not ["all" deleted] have originated in a polar Lat. under the one created form. & migrating South have diverged into others. I do incline to this latter doctrine - to account for [illegible word deleted] some cases, & to account for others I assume that the species are not distinct at all anywhere" (Archives, Gray Herbarium Library). So Gray was not unprepared for the letter that Darwin was to write to him a year later. At the instigation of Lyell and with the qualified concurrence of Hooker, in May 1856 Darwin began work on what he initially termed his "Species Sketch," which metamorphosed into Natural Selection. A draft of chapter 7, "Laws of Variation: Varieties & Species Compared," was probably completed by July 5, and then chapter 8, "Difficulties on the Theory of Natural Selection in Relation to Passages from Form to Form," was begun (C. Darwin 1975). It was while writing the latter chapter that Darwin once again wrote a monumental letter to Gray. There is no mention of Gray in the chapter, so the impetus for writing at this time probably came from a letter from Gray, not from the subject matter of the chapter. However, is touched upon in the chapter, and Gray's letter to Darwin of July 7, 1857, discusses the subject, so that may prove the reason why Darwin wrote at this time. In addition, Gray wrote: "If I had ever thought over the matter, and investigated it as you have, very likely I should think quite differently. But it is just such sort of people as I that you have to satisfy and convince, and I am a very good subject for you to operate on, as I have no prejudice nor prepossessions in favor of any theory at all" (Burkhardt and Smith 1990:423). This invitation to Darwin to explain more fully his ideas on extinction, mentioned briefly in his letter of June 18 to Gray, gave him the perfect opportunity to add Gray to Hooker and Lyell as another confidant. Darwin's first letter to Gray to discuss evolution was dated July 20, 1857, and responded to Gray's letter of July 7. It began:

What you say about extinction, in regard to small genera & local disjunction, being hypothetical seems very just. Something direct, however, could be advanced on this head from fossil shells; but hypothetical such notions must remain. It is not a little egotistical, but I sh. d like to tell you, (& I do not think I have) how I view my work. Nineteen years (!) ago it occurred to me that whilst otherwise employed on Nat. Hist., I might perhaps do good if I noted any sort of facts bearing on the question of the origin of species; & this I have since been doing. Either species have been independently created, or they have descended 26 DUNCAN M. PORTER

from other species, like varieties from one species. I think it can be shown to be probable that man gets his most distinct varieties by preserving such as arise best worth keeping, & destroying the others, - but I sh d. fill a quire if I were to go on. To be brief I assume that species arise like our domestic varieties with much extinction; & then test this hypothesis by comparison with as many general & pretty well established propositions as I can find made out, - in geograph, distribu- tion, geological history - affinities &c &c &c.. And it seems to me, that supposing that such hypothesis were to explain such general propositions, we ought, in accordance with common way of following all , to admit it, till some better hypo- be found out. For to my mind to say that species were created so & so is no scientific explanation only a reverent way of saying it is so & so. But it is nonsensical trying to show how I try to proceed in compass of a note. But as an honest man I must tell you that I have come to the heterodox conclu- sion that there are no such things as independently created species - that species are only strongly defined varieties. I know that this will make you despise me. - I do not much under- rate the many huge difficulties on this view, but yet it seems to me to explain too much, otherwise inexplicable, to be false. Just to allude to one point in your last note, viz about species of the same genus generally having a common or continuous area; if they are actually lineal descendants of one species, this of course would be the case; & the sadly too many exceptions (for me) have to be explained by climatal and geo- logical changes. A fortiori on this view (but on exactly same grounds) all the individuals of the same species sh. d have a continuous distribution. On this latter branch of the subject I have put a chapter together, & Hooker kindly read it over: I thought the exceptions & difficulties were so great that on the whole the balance weighed against my notions, but I was much pleased to find that it seemed to have considerable weight with Hooker, who said he had never been so much staggered about the permanence of species. (Burkhardt and Smith 1990:431-432)

The "chapter" that Hooker read over was chapter 11, "Geographical Distribution," of Natural Selection, which was completed in July 1856 and a copy sent to Hooker in October. A further, longer letter was sent to Gray on September 5, which gave an outline of Darwin's 1844 essay. It is an extract of the latter that was included as part of the Darwin-Wallace "joint paper" discussed below, not On the Road to the Origin with Darwin, Hooker, and Gray 27 the former letter of July 20. Darwin's outline and Hooker's letters were a boon to Gray, who was grateful for the theoretical frame- work they supplied him in his struggle against the idealistic species concept of Agassiz, who preached that "a species is a thought of the Creator" (Dupree 1959:248). Now both Hooker and Gray knew what Darwin was up to. On August 27, 1857, Hooker wrote to Gray:

With regard to versus Physics, I suppose you think me hopelessly heterodox; I hate the class of subjects, but I must acknowledge to be of those who cannot see that it is either honorable to the Deity to have made species by separate ["creations" deleted] impulses, or dishonorable to have made them by transmutation5 - in neither case do we approach the mystery of creation. Nor in like manner can I conceive it at all derogatory to the most exalted conception of the Deity to suppose vitality to be another manifestation of Physics, & correlatable [?] with ["referable to manifestations of" added] Heat, Mag- netism, Motion, Sound, &c. which are all different manifesta- tions of ["one another" deleted] one & the same force - You seem to think this materialism, I do not, any more than it is to ["connect" deleted] correlate the fate of a stone with the motions of the planets, which was once Blasphemy or next door to it. (Archives, Gray Herbarium Library)

Theology is now entered into their discussion, which is not surprising given that both Hooker and Gray were regular church- goers. With Darwin, who once planned on becoming a country vicar but who had long since left religion behind, there was no such discourse. Gray answered this letter on October 12, after having received the September 5 letter of Darwin:

Now I am much interested in Darwin's endevors and write him so. That vein has got to be worked: and we are much interested to have it done by a true naturalist & an honest & unprejudiced one. A better man to do it than D cannot be found. When we see how races are evolved,6 and how various are the degrees of resemblance between what we call species of the same genus, - & how impossible it is to do more than guess what are species & what are varieties, we cannot avoid asking

5. This is the first time that the term appears in their correspondence. 6. The first time this term appears in the correspondence. 28 DUNCAN M. PORTER

whether there is not some law of development of species. - It is a true scientific question; and whether it is rendered the more probable hypothesis, I shall feel no hesitation in adopting it as such - certainly, with [i.e., which] you shall not, and do not think derogatory to the Deity to originate the diversity of plants and animals in this way. Very presumptuous it would be for any man to say that. And so of the relations of Vitality to physics. We are getting new light as to the relations, but I do not believe you are going to homologize them then. When you do I will accept it like anything else proved. More likely, it may be shown how vitality directs the expenditure or transformation of physical force - i.e. makes physical force transform matter in peculiar ways. (Royal Botanic Gardens, Kew Correspondence/Asa Gray~1839-1873, p. 155v)

There is much similar discussion in the many letters that passed between Gray and Hooker at this time.

CONCLUSION

Then, on June 18, 1858, while he was still working on the manuscript for Natural Selection, Darwin received a fateful letter from the naturalist Alfred Russel Wallace. Wallace had been collecting zoological specimens in the East Indies since 1854, having done the same in in 1848-1852. Like Darwin, he had experience with biotas in different areas of the tropics, and also like Darwin he began to wonder about their origins and relation- ships. Wallace first wrote to Darwin from Celebes in October 1856. In his answer of May 1, 1857, Darwin indicated that they had much in common:

By your letter & even still more by your paper in Annals, a year or more ago [Wallace 1855], I can plainly see that we have thought much alike & to a certain extent have come to similar conclusions .... This summer will make the 20th year (!) since I opened my first note-book, on the question how & in what way do species & varieties differ from each other. - I am now preparing my work for publication, but I find the subject so very large, that though I have written many chapters, 7 I do not suppose I shall go to press for two years. (Burkhardt and Smith 1990:387)

7. Seven plus, by this date. On the Road to the Origin with Darwin, Hooker, and Gray 29

Thus, it is not surprising that Wallace would write to Darwin regarding the origin of species. What was surprising was that in March 1858 Wallace sent a letter that contained the manuscript "On the Tendency of Varieties to Depart Indefinitely from the Original Type." Upon its receipt, Darwin wrote to Lyell, on June 18, the now well-known lines: "I never saw a more striking coincidence. If Wallace had my M.S. sketch written out in 1842 he could not have made a better short abstract! Even his terms now stand as Heads of my Chapters" (Burkhardt and Smith 1991:107). Following consultation with LyeU and Hooker, Wallace's paper was read at a meeting of the Linnean Society of London on the first of July. It was presented along with extracts from Darwin's 1844 essay and an abstract of his September 5, 1857, letter to Gray. The latter obviously were included in order to assure Darwin's priority for the ideas discussed. Neither Darwin nor Wallace was in attendance. Wallace was still in the , to remain there until 1862. Darwin was in Down, grieving over the death of his infant son Charles Waring Darwin on June 28 from scarlet fever, and worrying about the other children. The Darwin-Wallace so-called joint paper was published in the Journal of the Proceedings of the Linnean Society of London on August 20, 1858 (Darwin and Wallace 1858a). It was entitled "On the Tendency of Species to Form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection," by Charles Darwin and Alfred Wallace, communicated by Sir Charles Lyell and J. D. Hooker. It consisted of three parts: "Extract from an Unpublished Work on Species, by C. Darwin, Esq. Consisting of a Portion of a Chapter Entitled, 'On the Variation of Organic Beings in a State of Nature; on the Natural Means of Selection; on the Comparison of Domestic Races and True Species'"; "Abstract of a Letter from C. Darwin, Esq., to Prof. Asa Gray, Boston, U.S., dated DOwn, September 5th, 1857," by Darwin; and "On the Tendency of Varieties to Depart Indefinitely from the Original Type," by Wallace. In spite of its providing the first acceptable scientific explana- tion for the evolution of species, the Linnean Society presentation appears not to have made much of a mark. This is perhaps under- standable, as Robert Brown, President of the Society from 1849 to 1853 and a member of the Linnean Society Council, had died on June 10. The meeting was held for the purpose of electing a successor to Brown on the Council and of reading papers postponed from the previous meeting, as well as eulogizing Brown. Following the usual announcements of gifts to thelibrary and herbarium of 30 DUNCAN M. PORTER the Society, George Bentham was elected to its Council, and was then nominated and elected to replace Brown as its vice-presi- dent. Then came the lengthy eulogy of Robert Brown. Only after this, late in the evening, were the papers read, beginning with Darwin and Wallace, followed by five postponed from the meeting of June 17. A sixth paper, "Notes on British Botany" by Bentham, was withdrawn: Bentham had intended to expostulate on the fixity of species, but on hearing the arguments of Darwin and Wallace, "These views were so antagonistic to those which Bentham had drawn up, that he withdrew his paper unread" (Jackson 1906:179). Given the length of the meeting and the number of presentations, it is no wonder that there was little or no discussion of natural selec- tion. J. W. T. Moody's summation of the evening is undoubtedly right on the mark: "The fellows were not so much stunned by new ideas as they were overwhelmed by the amount of information loaded upon them at the meeting. Much of the Darwin-Wallace concept of natural selection went over their heads. This in large measure was the result of insufficient time to concentrate atten- tion and discussion upon the Darwin-Wallace papers. Some of the silence was no doubt boredom, a constant danger of long meetings" (1971:476). There was more published reaction to the "joint paper" than is currently realized. It was cited nine times before the publica- tion of the Origin in November 1859. Richard Owen referred to it in his presidential address to the British Association for the Advancement of Science in September 1858 (Owen 1859). The ornithologist Rev. (1822-1906) discussed its ideas in a paper on the birds of northern Africa presented in March 1859 (Tristram 1859). Tristram was the first besides Darwin or Wallace to use natural selection as a working hypothesis (Cohen 1985). In a postscript appended to the fourth volume of his Cybele Brittanica, published in April 1859, H. C. Watson wrote that, had Darwin's views "on the mode in which varieties may supplant their ancestral species" been published earlier, he would have modified his discussion on the "inequality and the permanence of species" (Watson 1859:524, 525). Asa Gray referred to the "joint paper" in a footnote to a discussion of the geographical distribution of plants in an essay on the flora of Japan published in April 1859 (A. Gray 1859). Joseph Hooker mentioned it in the "Introductory Essay" to the , dated November 4, 1859, but published on February 6, 1860 (Turrill 1953). In addition, in his presidential address to the Geology Section of the British Association for the Advancement of Science in September 1859, Lyell announced that Darwin was On the Road to the Origin with Darwin, Hooker, and Gray 31 soon to publish a work that would throw "a flood of light" on the origin of species (Lyell 1860). All the foregoing were favorable in their comments on Darwin and Wallace's hypothesis. All but Tristram had prior knowledge of Darwin's interest in variation or transmutation. Owen and Tristram, however, soon changed their minds. Contrary arguments were soon provided by Rev. (1821-1897), Professor of Geology at Trinity College, Dublin, in his presidential address to the Geological Society of Dublin on February 9, 1859: "This speculation of Messrs. Darwin and Wallace would not be worthy of notice, were it not for the weight of authority of the names under whose auspices it has been brought forward [i.e., Lyell and Hooker]. If it means what it says, it is a truism; if it means anything more, it is contrary to fact" (Haughton 1859:225). Following a quick reprinting of the joint paper in the Zoologist (Darwin and Wallace 1858b), two further papers appeared in this journal questioning Darwin and Wallace's claims. Both the entomologist Thomas Boyd (1829-1913) and Rev. Arthur Hussey (1794-1862) were more critical of Wallace's views than of Darwin's (Boyd 1859; Hussey 1859). Finally, on November 10, 1859, two weeks before the publication of the Origin, Andrew Murray (1812-1878), Scottish lawyer and botanist, gave his presidential address to the Botanical Society of Edinburgh. Much of it consisted of a critical review of Gray's paper on the flora of Japan (A. Gray 1859) cited above. Murray admitted that "the theory has excited much attention" (1860:148). However, he dismissed the argument of the "joint paper" and that of the Origin, which he had read in page proof sent him by "a friend." These negative reactions came from those who had no prior knowledge of Darwin's ideas. Presumably, the others who were aware of Darwin's work were awaiting its further elucidation in the Origin. On September 23, 1858, Hooker wrote to Gray:

I shall be glad of your opinion of Darwin & Wallaces paper, I must own that my faith is shaken to the foundation, & that the sum of all the evidence I have encountered since I studied the subject is in favor of the origin of species by ["transmutation" deleted] variation. I feel (& I should like to know your feelings) that had I been originally taught the transmutation doctrine, as a dogma (like ["as/" deleted] as I was taught the creation doctrine) - I should have stuck to it to this hour & been convinced of it - if only from the evidence accumulated since my teaching. The worst of it is, that I cannot believe progres- sion - & so am no nearer the mystery of the origin of created 32 DUNCAN M. PORTER

things - which is however quite a different question. (Archives, Gray Herbarium Library)

Gray responded on October 11:

I know of Darwin & of Wallace's views only from Darwin's letters, and only in a general way. 81 purposely keep from forming any opinion until I get the main facts & arguments well before me. But I see a very strong case can be made. I see that I can go some way with D. But whether the whole way is doubtful. For some time before I knew Darwin's views, I wondered that somebody did not revise our notions of species by beginning with those we are supposed to know most of, viz - domesti- cated species, and shown that the strong tendency to form races was by no means at all peculiar to them, but the exemplifica- tion of a common law. I have no prejudice against the coming view, I believe. - I believe we have lots of derived species, but still suppose it most likely that there are plenty of aboriginal ones - that nobody will be successful in the attempt to trace all congeneric plants to one common specific type, still less all coordinate species to one origin. Nous verrons. (Royal Botanic Gardens, Kew Correspondence, Asa Gray/1839-1873, pp. 194-194v)

So both Gray and Hooker still retained reservations as to how much of the evolutionary process natural selection could explain. Hooker was never able to accept the action of natural selec- tion in the origin of life, but he found that it explained the origin of species. He confessed to Gray on October 21, 1858:

I am very busy with the Introductory Essay to Flora of Tasmania, a kind of composition I find most hard - I have to make large concessions to Darwin's Doctrines of "Natural Selection" and have altogether modified my opinion much on the subject of hybrids, - varieties - returning to parent form - & many other cardinal points. I have many difficulties, 1. To bring the ["matter" deleted] subject into my essay gracefully. & not as if lugged in apropos of nothing - 2. To state clearly the extent & direc- tion of my modified views; 3. To deal to good purpose with the 9000 Australian species which I have catalogued with habitats, & draw out something to the purpose anent the ratio-

8. Darwin had outlined his views in a letter of August 11. On the Road to the Origin with Darwin, Hooker, and Gray 33

nale of the Australian Flora. 9 4th. To harmonize the facts drawn out with the old Creation doctrine & the new Natural Selection doctrine. Most thankful I am that I now can use Darwin's doctrines - hitherto they have been secrets I was bound in honor to know, to keep, to discuss with him in private & to combat if I could, in private - but never to allude to in public, & I had always in my writings to discuss the subjects of creation variation &c &c as if I had never heard of Natural Selection - which I have all along known & feel to be not only useful in itself as explaining many facts in variation, but as the most fatal argument against "Special Creation" & for "Derivation" [changed from "Derivative" and "species" deleted] being the rule for all species. (Archives, Gray Herbarium Library)

Thus did Hooker embrace natural selection. Indeed, he addressed these issues in his "Introductory Essay" to the Flora Tasmaniae (J. Hooker 1855-60). Gray, on the other hand, was not willing to go as far as Hooker in accepting the principle of natural selection - either in further correspondence with him or Darwin, after reading the "Introductory Essay" to the Flora Tasmaniae, or after the Origin was published. Although Gray became Darwin's chief defender in the New World, he continued to argue that natural selection was a plausible hypo- thesis, which explained most of the facts regarding the derivation of species but which was still unproven. These arguments appeared in a series of essays published in the 1860s and 1870s and were gathered together to form Darwiniana (A. Gray 1876) - an eloquent defense of Darwin, if not of natural selection. Hooker, in spite of his long knowledge of Darwin's ideas and his firm belief in natural selection, did not become the English spokesman for evolution, as might have been predicted. This role was taken up by T. H. Huxley, who was perhaps by temperament better suited to become "Darwin's ." Hooker never enjoyed public speaking. His only experience at regularly lecturing was in 1845, when he substituted for a term for the ailing (1786--1845), Regius Professor of Botany at Edinburgh University. He approached the lectures with trepidation, but soon found himself doing at least an acceptable job (L. Huxley 1918, 1:194-201). The one speech Hooker delighted in having given, however, was at the British Association Meeting in Oxford on June 30, 1860. In answer to Rev. (1805-1873),

9. The relationships within the Australian flora and between it and other floras. 34 DUNCAN M. PORTER

Bishop of Oxford, who ridiculed Darwin, his ideas, and his supporters, especially Huxley, Hooker shone. He wrote to Gray five days later:

We have had an awful fight at the Brit. Assn. about it [natural selection] - into which I was driven wholly against my avowed intentions - but the Bishop of Oxford, crammed by Owen, thought to pooh-pooh all Naturalists by a stunning display of Oratory, & Huxley & I gave ["them" deleted] him the most tremendous thrashing he ever got in his life - in the presence of nearly 1000 people. I Spoke only once, the last of all, showed that he could never have read Darwins book & expressed[?] igno- rance of the elements [?] of Science. - I shut him up completely, he had not a word to reply, & the discussion was hence closed amid rounds of applause for my side. (Archives, Gray Herbarium Library)

This confrontation is usually remembered for Huxley's answering the bishop's query "whether Huxley was related by his grand- father's or grandmother's side to an " (Sir Charles Lyell, quoted in E Darwin 1887, 2:115), with:

I asserted, and I repeat, that a man has no reason to be ashamed of having an ape for his grandfather. If there were an ancestor whom I should feel shame in recalling, it would be a man, a man of restless and versatile intellect, who, not content with an equi- vocal success in his own sphere of activity, plunges into scien- tific questions with which he has no real acquaintance, only to obscure them by an aimless rhetoric, and distract the attention of his hearers from the real point at issue by eloquent digres- sions, and skilled appeals to religious prejudice. (John Richard Green, quoted in E Darwin 1887, 2:115)

Huxley's words ultimately have gained him the most publicity, but Hooker's were more persuasive at the time. A contemporary report on this meeting in the Athenaeum (1860) briefly mentions Huxley's remarks but gives those of Hooker in detail. On the other hand, Huxley was the perfect spokesman for Darwin, making his living lecturing at the Royal School of Mines, at the , and to various groups in Britain and the United States. His lectures and scientific and popular writings brought the ideas of evolution to many who would not or could not read the Origin. Years later, Huxley was to write: On the Road to the Origin with Darwin, Hooker, and Gray 35

My reflection, when I first made myself master of the central idea of the "Origin" was, "How extremely stupid not to have thought of that!" I suppose that Columbus' companions said much the same when he made the egg stand on end. The facts of variability, of the , of to conditions, were notorious enough; but none of us had suspected that the road to the heart of the species problem lay through them, until Darwin and Wallace dispelled the darkness, and the beacon-fire of the "Origin" guided the benighted. (in F. Darwin 1887, 1:551)

As we have seen, Hooker, Gray, and Lyell were privy to these ideas before their publication in 1858 and 1859, but Huxley was not. It was Huxley's good fortune to have his reputation enhanced by extolling Darwin, and it is his name that is now most inti- mately linked with Darwin's in the minds and writings of most and historians. Scientifically, however, Darwin profited much more from his friendships with Hooker and Gray than he did from that with Huxley. Of his many correspondents at this time, they were the ones upon whom Darwin relied most heavily for data and discussions on evolution.

Acknowledgments

I wish to thank Richard K. Bambach, Frederick H. Burkhardt, Sarah H. Porter, Richard Burian, Norman Gilinsky, and Peter F. Stevens for their helpful comments on earlier drafts of this paper. Research in England was made possible by grants from the American Philosophical Society and Virginia Polytechnic Institute and State University. Unpublished letters from the archives of the Gray Herbarium, Harvard University, and the Royal Botanic Gardens, Kew, are here published with permission; access to them was provided by Hollis Beddell and Judith Warnement, and Sylvia Fitzgerald and Leonora Thompson, respectively. Published letters from The Correspondence of Charles Darwin are here used with the permission of the Syndics of Cambridge University Press. An earlier version of this paper was presented at the conference "Landmarks in Natural History" at the Annual General Meeting of the Society for the History of Natural History, , London, in April 1990.

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