In 1807 De Candolle was made Professor of Botany in the Faculty of Medicine at the university of Montpellier. In 1810, a chair of Botany being constituted in the Faculty of Sciences of the same place, he was appointed to it. During his residence at Montpellier he devoted much time to the botanic garden; and published a catalogue of the plants contained in it, with descriptions of many new species. Circumstances however occurred which led him to quit Montpellier, and in 1816 he returned to his native city, which was restored to its independence on the re-establishment of the Bourbons on the throne of France. A chair of natural history was established especially for him at Geneva. In the same year he visited England to examine the collections of plants in the British Museum, the Linnman and other societies, for the purpose of aiding him in the publication of his great work on the vegetable kingdom.
In 1818 appeared the first volume of this work, intended to com prehend a description of all known plants. He had in a measure enunciated the principles on which this work would be based by the publication of his ' Th6orie Elementaire,' in 1813. In this work he not only carried out the principles of a natural arrangement of plants, which had been previously developed by Juseieu and Adaneon, but by a more extended study of the priociples of morphology he was enabled to clear up many of the difficulties which existed in the grouping of plants in previous classifications. Whatever may be the claims of previous writers in this department of botanical inquiry, to De Candolle must be conceded the merit of giving definite expressions for the various causes which act upon the structure of plants, and pointing out the relation between abnormal forms in individual plants and normal forms in particular groups.
The natural system of the vegetable kingdom however was only commenced ; a 'second volume appeared in 1821, but the author was obliged to abandon the design, as a work of too great magnitude. He therefore in 1824 commenced the publication of a l'rodromus of the larger work. But even this proved a work too extensive for com pletion during his lifetime. This work embraced descriptions of all the known species of plants. Commencing with the phanerogamone plants, each order in the natural system was exhausted as far as the materiale of the author would allow. All the orders belonging to the polypetalous division of Exogens were completed, as well as the orders of the monopetalous division as far as the Compositor. To this last
difficult order De Candolle had paid much attention, and his desire to give it In as perfect a form as possible led him to devote so much time to it as materially to injure his health. The work wee left Incomplete at Ills death, but partly from the materials which he had collected it was continued by his son, assisted by other eminent botanist'. The importance of this publication to the working botanist can hardly be overrated, as it supplies him with the means of recog nising a Treat number of species that had before been either undencribed or inaccessible to the student from the places in which they were published. Another point which enhances the value of this work is the care which the author bestowed in drawing up the descriptions of plants, which could not have been done so well by any one who possessed a less extensive herbarium and library than himself.
But although the labour bestowed on this great work, and the judgment with which It was executed, have given It the most pro minent position amoogst ble works, it can only be regarded as the result of an accurate knowledge of the structure and function of plants. On this subject be lectured for many years, and although frequently producing monographs on various department's of botany, which Indicated his knowledge of vegetable anatomy and phyelolou, it was not till 1827 that he published his lOrganographie V6g6tode.' In this work he proceeded on the principle of tracing each organ through all its several modification' of structure In the different plants in which It occurs, and of reducing every part to its organic' elements. It is thus not a mere detail of particular structure'', but • development of the great doctrine of metamorphosis, which lied been exphdned in his previous work on the principles of classification. This work was followed in 1832 by one on the physiology of plants. This was a comprehensive digest of all that had been done up to the period at which it was written. It was however published nt.a time when the chemist and physiologist were both turning their attention to the functions of the vegetable, as affording the means of better understanding the nature of the functions of the animal, and coose quently many of the views of the author have had to give way before more extended investigation.