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HOOKER, Sir JOSEPH DALTON (1817–1911), botanist and traveller, younger son of Sir William Jackson Hooker [q. v.] and his wife Maria, eldest daughter of Dawson Turner, F.R.S. [q. v.], was born at Halesworth, Suffolk, on 30 June 1817. At Glasgow he received in the high school the old-fashioned Scottish liberal education which enabled him afterwards to write Latin with facility. In the university, where his father was regius professor of botany, Lord Kelvin [q. v. Suppl. II] and Lord Sandford [q. v.] were fellow-students and remained lifelong friends; he studied moral philosophy, which he thought in after life had been of little service to him. Devoting himself mainly to medicine, he graduated M.D. in 1839.

Hooker imbibed from his father a passion for botanical research, and from his youth was inspired with a keen desire to indulge it by foreign travel. This was first gratified when 8ir James Clark Ross [q. v.], a friend of his father, offered to take him. if ho qualified in time, nominally as assistant surgeon, but actually as naturalist, on his own ship, the Erebus, on the Antarctic expedition. Thus Hooker, like Darwin and Huxley, 'began his scientific career on board one of Her Majesty's ships.' The filiation of Hooker's life-work to that of Darwin had an accidental origin. Charles Lyell of Kinnordy, father of Sir Charles Lyell [q. v.], had lent Hooker the proof-sheets of Darwin's 'Journal.' He was hurrying on with his studies and slept with them under his pillow to read at daybreak. They impressed him 'despairingly with the variety of acquirements, mental and physical, required in a naturalist who should follow in Darwin's footsteps.' He was casually introduced to Darwin in Trafalgar Square, and Lyell sent him a published copy of the 'Journal' on the eve of his departure. The Erebus sailed from Chatham on 29 Sept. 1839. Besides magnetic survey the collection of 'various objects of natural history' was 'enjoined to the officers.' There were three breaks in the voyage during southern winters, in Tasmania, New Zealand, and the Falklands, and these afforded Hooker ample opportunity for collecting.

On the return of the expedition in 1843 Hooker at once commenced the publication of the botanical results. They fill six quarto volumes {1844r-60), with 2214 pages and 528 plates ; two are devoted to the flora of the Antarctic Islands ('Flora Antarctica,' 1844-7), two to that of New Zealand (1852-4), and two of Tasmania (1855-60). The treasury made a grant of 1000l. to be expended on the plates. But beyond an honorarium of 350l. from each of the two colonies he received no remuneration.

Darwin had through the elder Lyell read the letters sent home by Hooker, and began a lifelong correspondence by warmly congratulating him on his return in December 1843. The intercourse of the two for the next fifteen years is a memorable page in scientific history. The permanence of species was substantially the belief with which Darwin, Hooker, and Huxley started on their expeditions. Fossil remains in South America convinced Darwin that the present inhabitants of a given area though similar were not identical with their predecessors in the pant; there had been an evolution in time. The animals and plants (worked out by Hooker in 1845-6) of the Galapagos, though related, differed in each island ; the inevitable conclusion was that there had been an evolution in space. Species were clearly not permanent ; and an explanation was needed. Hooker found that identical species occurred in islands 'separated by 3000 miles of ocean' ; was it to be concludecl, as Agassiz thought, that species had multiple origins ?

On 14 Jan. 1844 Darwin wrote to Hooker, 'I think I have found out the simple way by which species become exquisitely adapted to various ends.' This was natural selection ; Hooker was the first to whom the theory was confided, and he read at the same time the first sketch of the 'Origin' (printed in 1909 by Mr. Francis Darwin). The confidence proved afterwards of no small importance. During the next fourteen years in which Darwin was occupied in elaborating his theory, he was almost in continuous correspondence with Hooker with regard to its details. 'The intimacy,' which began in 1843, 'ripened [on Hooker's side] into feelings as near to those of reverence for [Darwin's] life, work and character as is reasonable and proper' (L. L. ii. 20). Darwin for his part could write to him in 1862 : 'For years I have looked to you as the man whose opinion I have valued more on any scientific subject than anyone else in the world ' (M. L. ii. 284). Writing to Lyell in 1866, Danvin said : 'his [Hooker's] mind is so acute and critical that I always expect to hear a torrent of objections to anything proposed ; but he is so candid that he often comes round in a year or two' (M. L. ii. 138).

Darwin and Hooker were both ultimately inspired by Lyell. Darwin's problem was how species originate ; Hooker's how they are distributed over the surface of the earth. If they worked on parallel lines, they mutually re-acted on one another, and Darwin saw clearly that the distribution problem was an essential feature in any evolutionary theory. Writing to Hooker in 1845, he said, 'I know I shall live to see you the first authority in Europe on that grand subject, that almost keystone of the laws of creation, geographical distribution' (L. L. i. 336).

In his 'Flora Antarctica' Hooker rejected emphatically the theory of 'multiple origins,' the supposition that the same species may have originated in more than one area. Darwin thought their occurrence in widely separated islands was explained by physical means of transport, and the present trend of opinion is on his side. Hooker told him that following Edward Forbes [q. v.] he was driven to 'the necessity of assuming the destruction of considerable areas of land to account for it' (L. L. ii. 20). This was the view adopted in the 'New Zealand Flora' in 1854.

In 1845 Hooker was a candidate, with the support of Humboldt and Robert Brown [q. v.], for the chair of botany at Edinburgh, but was unsuccessful. Immediately afterwards he was appointed botanist to the Geological Survey. His work in a new field was brilliant ; in papers published in 1845 he threw light on the structure of Stigmaria and Lepidostrobus, and in 1852 explained Trigonocarpon. He did no further work in fossil botany after 1855.

Hooker wrote to Darwin in 1854, 'from my earliest childhood I nourished and cherished the desire to make a creditable journey in a new country' (M. L. i. 70). This was gratified in 1847 (in which year he was elected F.R.S.), when Lord Carlisle, then chief commissioner of woods and forests, obtained for him a grant of 400Z. wherewith to explore for two years the central and eastern Himalaya. The earl of Auckland wished this to be followed by a visit to Labuan, for which he received a commission in the navy. But this part of the scheme fell through with Lord Auckland's death in 1849. The admiralty sent him out to Egypt in H.M.S. Sidon with Lord Dalhousie, who attached him to his suite. Part of 1848 and 1849 was spent in exploring Sikkim, where he was the guest of Brian Hodgson [q. v.]. In the latter year he was joined by Dr. Campbell, the government agent, and owing to some intrigue in the Sikkim court they were both temporarily imprisoned. He was able to explore part of Eastern Nepal, in which no traveller has since succeeded in following him. He surveyed single-handed the passes into Tibet, and the Lhasa expedition in 1903 sent him a telegram from Khambajong congratulating him on the usefulness of his survey. His observations on the geology and meteorology of Sikkim are still fundamental, and he explained the terracing of mountain valleys by the formation of glacial lakes. He succeeded in introducing into cultivation through Kew the splendid rhododendrons of Sikkim, which were worthily illustrated from his drawings in a work edited by his father (1849-51) and published during his absence. Hooker spent 1850 in travelling with Thomas Thomson (1817-1878) [q. v.] in Eastern Bengal and the Khasia Hills. They returned to England together in 1851. The result of the expedition was a collection of plants representing 6000 to 7000 species. The treasury gave him a grant of 400l. per annum for three years to name these and distribute the duplicates (sixty herbaria were recipients), and to write the 'Himalayan Journals' (1854; 2nd edit. 1855), which have become a classic. In 1855 he published 'Illustrations of Sikkim-Himalayan Plants,' including Hodgsonia, the gigantic cucurbit dedicated to his friend Hodgson.

In 1855 Hooker was appointed assistant director at Kew, and with Thomson published his first volume of a 'Flora Indica,' which, planned on too large a scale, did not proceed further. It was prefaced by an introductory essay on the geographical relations of the flora which has never been superseded. The authors regard species as 'definite creations' (p. 20). But both Darwin and Hooker were always in agreement that species for purposes of classification must be accepted as facts, whatever view be taken as to their origin. Huxley, however, thought Hooker in the following year 'capable de tout in the way of advocating evolution' (L. L. ii. 196).

In 1858 an event happened which Darwin's friends had long anticipated. On 15 June Darwin received from Dr. Alfred Russel Wallace, who was then in the Celebes Islands, an essay which substantially embodied his own theory. The position became tragic, for on 29 June Darwin was prostrate with illness ; scarlet fever was raging in his family and an infant son had died of it the day before. Lyell and Hooker acted for him ; an extract from an abstract of the theory shown by Darwin to Hooker and read by the latter in 1844 was communicated with Wallace's essay to a meeting of the Linnean Society on 1 July 1858. Darwin's 'Origin' itself appeared in Nov. 1859. Four months earlier Hooker published his 'Introductory Essay on the Flora of Tasmania,' by far the most noteworthy of his speculative writings. In this he frankly adopts, in view of the Darwin-Wallace theory, the hypothesis 'that species are derivative and mutable.' The essay is in other respects remarkable for the first sketch of a rational theory of the geographical distribution of plants, besides giving a masterly analysis of the Australian flora.

In the autumn of 1860 John Washington [q. v.], hydrographer of the navy, invited Hooker to take part in a scientific expedition to Syria. The cedar grove on Lebanon was examined and found to be on an old moraine 4000 feet below the summit, which is no longer covered with perpetual snow. The climate must formerly, therefore, have been colder. Under such conditions he speculated as to the possibility of the Lebanon, Algerian, and Deodar cedars having been parts of continuous forest at a lower level.

In the same year Hooker began with his friend George Bentham [q. v.] the 'Genera Plantanim,' a vast undertaking, the first part of which was issued in 1862, the concluding in 1883. It is written in Latin ; it aims at establishing a standard of uniformity in classification ; it is based throughout on first-hand study of material ; and it is a mine of information for the study of distribution. Reichenbach found in Hooker's work that 'touch of genius which resolves difficult questions of affinity where laborious research has often yielded an uncertain sound.'

In 1862 he contributed to the Linnean Society his classical memoir 'Outlines of the Distribution of Arctic Plants,' in which he worked out in detail 'the continuous current of vegetation which extends from Scandinavia to Tasmania, the greatest continuity of land of the terrestrial sphere.'

In 1865 Hooker's father died. At the time Hooker was himself prostrated with rheumatic fever. He succeeded his father in the directorship at Kew, and for the next twenty years administrative duties of the most varied kind limited seriously the time available for scientific work. At the British Association at Nottingham in 1866 he delivered a lecture on 'Insular Floras.' He described the problem as the bete noire of botanists. He frankly abandoned 'sinking imaginary continents,' and found a rational explanation in trans-oeanic migration. In 1867 was completed a ' Handbook of the New Zealand Flora' for the colonial government, and he edited the fourth volume of the 'Illustrations of the Genus Carex' left unfinished on the death of liis friend Francis Boott [q. v.].

Hooker in 1868 presided over the British Association at Norwich. After the lapse of ten years he found 'natural selection an accepted doctrine with almost every philosophical naturalist.' He discussed Danvin's later theory of pangenesis which, at the time received with little favour, is now thought, as Hooker considered possible, 'to contain the rationale of all the phenomena of reproduction and inheritance.' In 1869 he attended at the instance of the government the International Botanical Congress at St. Petersburg.

In 1870 he produced his 'Student's Flora of the British Islands' (3rd edit. 1884). He had pointed out in 1853 that he knew of no 'Flora' 'which attempts to give a general view of the variation and distribution of the species described in it.' He now showed how this should be done.

An expedition to Morocco occupied April to June of 1871 in company with John Ball (1818-1889) [q. v.] and George Maw OS geologist. The main object was to explore the Great Atlas. The highest point reached was the Tagherot Pass (11,843 feet), the first time by any European ; descent into the Sous Valley was forbidden. An important result was the discovery that the Arctic-Alpine flora did not reach the Atlas. The interesting fact was observed that the practice of sacrificing animals as a propitiatory rite survived amongst the Berbers, and the travellers were themselves on one occasion the object of it. Hooker was unable to write more than a portion of the published 'Journal,' which was completed by Ball in 1878.

In 1850 Kew had passed from the generous control of the woods and forests to the less sympathetic of the office of works. In 1872 Hooker had what have been euphemistically described as 'protracted differences' with Acton Smee Ayrton [q. v. Suppl. I], the first commissioner. The scientific world saw clearly that the underlying question was the degradation of Kew to a mere pleasure garden. The differences were not settled without debates in both houses of parliament. Public opinion declared itself on Hooker's side. Gladstone transferred AjTton in August 1873 to another office, and the electorate dismissed him in 1874 from political life.

In 1873 the Royal Society elected Hooker president, with Huxley as joint secretary. Hooker's policy was to bring the society more into touch with the social life of the community. The ladies' soiree was instituted. On the other hand the privilege of election without selection was taken away from peers and restricted to privy councillors. In 1876 the Challenger returned from the voyage round the world 'originated' by the Royal Society and 'crowned with complete success.' In 1872 Hooker had drawn up for Henry Nottidge Moseley [q. v.] suggestions as to what could be done in the way of botanical collecting. Hooker was chairman of the committee of publication of the Reports (1876-95); fifty volumes were produced, the work of seventy-five authors, at an expenditure from public funds of some 50,000l. In 1878 Hooker laid down his office in a valedictory address. He was able to make one announcement which gave him peculiar pleasure. The Royal Society has little endowment, and the fees 'occasionally prevented men of great merit from having their names brought forward as candidates.' To allow of their reduction Hooker almost single-handed raised amongst his personal friends a sum of 10,000l.

This was in other ways a period of intense activity. In 1874 Hooker presided over the department of zoology and botany of the British Association at Belfast. He chose as the subject of his address 'The carnivorous habits of some of our brother organisms — plants.' In such cases he showed that vegetable protoplasm is capable of availing itself of food such as that by which the protoplasm of animals is nourished. In 1877, at the close of the session of the Royal Society, Hooker obtained an extended leave of absence to accept an invitation from Dr. Hayden, geologist in charge of the United States Geological and Geographical Survey of the Territories, 'to visit under his conduct the rocky mountains of Colorado and Utah, with the object of contributing to the records of the survey a report on the botany of those states.' Professor Asa Gray and Sir Richard Strachey [q. v. Suppl. II] were also members of the party. Hooker's report was pubHshed by the American government in 1881. His general conclusion was that the miocene flora had been exterminated in western North America by glaciation, but had been able to persist on the eastern side and in eastern Asia. In 1879 he returned to Antarctic botany, and rediscussed the flora of Kerguelen's Land as the result of the transit of Venus expedition in 1874. Its Fuegian affinities were confirmed though 4000 miles distant. He was more disposed to admit trans-oceanic migration, though still inclined to a former land-connection. In 1881 Hooker made geographical distribution the subject of his address as president of the geographical section at the jubilee meeting of the British Association at York.

With the completion of the 'Genera Plantarum' in 1883 Hooker was able to make a determined attack on his ' Flora of British India,' commenced with the collaboration of other botanists in 1855. This was completed in seven volumes in 1897 ; the number of species actually described approaching 17.000. The last four volumes were almost wholly from his own hand ; the Orchidece alone occupied him for two years.

His health began to fail, and under medical advice he retired from the directorship of Kew in 1885 to a house which he had built for himself at Sunningdale. While relieved of official cares he was able to continue his scientific work at Kew with renewed strength.

Shortly before his death Darwin had expressed a wish to aid ' in some way the scientific work carried on at Kew.' This took the shape of the 'Index Kewensis,' a catalogue of all published names of plants with bibliographical references and their native countries. The preparation entrusted to Mr. Daydon Jackson in 1882 occupied him for ten years ; the printing took from 1892 to 1895, during which time Hooker imposed on himself the laborious task of revising the whole.

In 1896 Hooker edited the 'Journal' of Sir Joseph Banks during Cook's first voyage from a transcript in the British Museum made by his aunts, Dawson Turner's daughters, the original having disappeared ; this transcript is now transferred to the Mitchell Library at Sydney. He then undertook (1898-1900) the completion of Trimen's 'Handbook of the Flora of Ceylon.' In the 'Imperial Gazetteer of India' (1907) he gave his final conclusions on the Indian flora, published in advance in 1904. His last literary effort was 'a sketch of the life and labours' of his father (Ann. of Bot. 1902).

Hooker's position in the history of botanical science will rest in the main on his work in geographical distribution. His reputation has amply fulfilled Darwin's early prophecy. It is difficult to say whether it is more remarkable for his contributions to its theory or to its data. De Candolle's classical work, 'Geographic Botanique raisonnee,' published in 1855, raised problems which he left unanswered ; Hooker solved them. As Asa Gray has justly said : ' De Candolle's great work closed one epoch in the history of the subject, and Hooker's name is the first that appears in the ensuing one.' As a systematist, his works exhibit a keen appreciation of affinity and a consistent aim at a uniform standard of generic and specific definition. As with his predecessor Robert Brown [q. v.], this was accompanied by great morphological insight. It was exhibited in his early palæontological work and in numerous studies of remarkable plants throughout life. His explanation of the origin of the pitcher in Nepenthes is substantially accepted. In 1863 he produced his great paper on the South African Welwitschia, which Darwin thought 'a vegetable ornithorhynchus' and Asa Gray 'the most wonderful discovery, in a botanical point of view,' of the century. In his last years he found recreation in studying the copious material which the exploration of Eastern Asia supplied in the genus Impatiens (balsams). They were the subject of thirteen papers, the last only appearing shortly after his death. Beginning with 135 species in 1862, he finally was able to recognise some 500.

The eminence of his work received general recognition. He received honorary degrees from Oxford, Cambridge, Dublin, Edinburgh and Glasgow. He was created C.B. in 1869; K.C.S.I. in 1877; G.C.S.I. in 1897; in 1907 the Order of Merit was personally presented to him at Sunningdale on behalf of King Edward VII on his ninetieth birthday, and he had the Prussian pour le mérite. From the Royal Society he received a royal medal in 1854, the Copley in 1887, and the Darwin in 1892; from the Society of Arts the Albert medal in 1883; from the Geographical their Founder's medal in 1884, and from the Manchester Philosophical its medal in 1898; from the Linnean in 1888, one specially struck on the completion of the 'Flora of British India' in 1898, and that struck on the occasion of the Darwin celebration in 1908; in 1907 he was the sole recipient from the Royal Swedish Academy of the medal to commemorate the bicentenary of the birth of Linnaeus. He was one of the eight associés étrangers of the French Académie des Sciences, and member of other scientific societies throughout the world.

Hooker was five feet eleven inches in height and spare and wiry in figure. There are portraits by George Richmond (1855) in the possession of his son C. P. Hooker, by the Hon. John Collier at the Royal Society, and by Sir Hubert von Herkomer at the Linnean, and a bronze medallion modelled from life by Frank Bowcher for the same society. He possessed great powers of physical endurance, and could work continuously with a small amount of sleep. In temperament he was nervous and high-strung; he disliked public speaking, though when put to it he could speak with a natural dignity and some eloquence. He completely outlived some heart trouble in middle life (doubtless of rheumatic origin). His mental powers retained unabated vigour and activity until the end. The summer of 1911 enfeebled him. What seemed a temporary illness compelled him at last to remain in bed. He passed away unexpectedly in his sleep at midnight at his house at Sunningdale on 10 Dec. 1911.

Tho dean and chapter of Westminster offered with public approval the honour of burial in the Abbey, where it would have been fitting that his ashes should be placed near Darwin. But at his own expressed wish he was interred at Kew, the scene of his labours.

Hooker was twice married: (1) in 1851 to Frances Harriet (d. 1874), eldest daughter of John Stevens Henslow [q. v.], by whom he left four sons and two surviving daughters; (2) in 1876 to Hyacinth, only daughter of William Samuel Symonds [q. v.], and widow of Sir William Jardine, seventh baronet [q. v.], by whom he left two sons.

[Personal knowledge; Gardeners' Chronicle, 16 Dec. 1911 to 30 Jan. 1912; Kew Bulletin, 1912, pp. 1-34 (with bibliography); Life and Letters of Charles Darwin, 3 vols. 1887 (cited as L.L.), and More Letters of Charles Darwin, 2 vols. 1903 (M.L.).]

W. T. T-D.