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
