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JUSSIEU

toine, at the request of the botanist Vaillant, and after Vaillant's death in 1722 was appointed the latter's successor as professor and assistant demonstrator at the Jardin du Roi. He devoted all his energies to the royal garden, which his brother Antoine left almost en- tirely to him. He also made botanical excursions in the country surrounding Paris, and was able in 1725 to issue a revised and enlarged edition of Tournefort's work, "Histoire des plantes des environs de Paris"; this publication gained his admission into the Acad- emy of Sciences. Many persons studied botany under his guidance, as the chemist Lavoisier. Owing to de Jussieu's imusual modesty and unselfishness he pub- lished very little, notwithstanding the wide range of his learning. He wrote an important paper on zoo- phytes, sea-organisms whose classification as plants or animals was then a matter of dispute. To study them he went three times to the coast of Normandy, proved in the " M^moires" of 1742 that they belonged to the animal kingdom (before Peyssonel), and sought to classify them at this early date into genera. He also separated the whale from the fish and placed it among the mammals. The few botanical papers which he published (1739—42) treat of three water-plants.

In 1758 Louis XV made de Jussieu superintendent of the royal garden at Trianon near Paris, in which all plants cultivated in France were to be reared. His greatest achievement is the system according to which he arranged and catalogued the plants in the garden at Trianon; it is called " the older Jus.sieu natural system of plants of 1759", or the Trianon system. Jussieu himself never published anything about his system, nor did he offer any explanation of his arrangement, or give it a theoretical foundation. The genera are not arranged systematically in groups according to a single characteristic, but after consideration of all the characteristics, which, however, are not regarded as of equal value. De Jussieu proposed three main groups, to which he gave no name; these contained altogether fourteen classes, with sixty-five orders or families. Be- ginning with the cryptogams, the system proceeds from the monocotyledon to the dicotyledon, and closes with the coniferae. Before this Linnaeus had pointed out that only the natural system should be the aim of botanical classification, and published, outside of his artificial system, fragments of a natural system as early as 1738. Compared to the present development of the natural system, both Linnajus and de Jussieu offer scarcely more than a weak attempt at a natural classification of plants, but their attempt is the first upon which the further development rests.

De Jussieu was a thoughtful observer of nature, who behind things saw the laws and the Mind which gave the laws. Notwithstanding the great range of his knowledge he was exceedingly modest and unsel- fish. He was always animated by an intense love of truth, and his influence in the Academy and over French scholars was very great. He was besides deeply religious, preserving his religious principles and acting upon them to the end of his life. An old biog- raphy says of him : " No one has proved better than he how religious feeling can be combined with many sci- ences and true knowledge." He was a member of nu- merous academies and learned societies, e. g. the acade- mies of Berlin, St. Petersburg, Upsala, London, and Bologna. In 1737 Linna>us named after him the genus Jussieua, which belongs to the family of the Onogracese, and at the present day includes some thirty-six tropical species, chiefly South American.

(3) JosKPii DE Jussieu, explorer and traveller, brother of the two mentioned atiove, b. at liVons, 3 September, 1704; d. at Paris, U April, 1779. Highly educated in many directions and able to act as physi- cian, botanist, engineer, and mathenialieian, he be- came a iiicinIxT of the scientific expedition sent by the Acadeni>' to Peruiin 1735 to measure an arc of the me- ridian. After the task of the expedition was completed

he remained in South America, supporting himself chiefly by the practice of medicine. His extended and arduous explorations in Peru took place mainly in the years 1747-50. The botanical results of these jour- neys were large, but the greater part of his manu- scripts and collections was lost, and he finally re- turned to Paris in 1771, broken in health and with a clouded mind. He sent the seed of the heliotropium peruvianum to his brother Bernard, so that the intro- duction of tills ornamental plant into Europe is due to him. He also undertook an investigation as to the area over which the cinchona tree flourishes and as to the first use of its bark by the Jesuits in South America. (4) Antoine-Laurent de Jussieu (botanical ab- breviation, Juss.), nephew of the above-mentioned three brothers, b. at Lyons, 12 April, 1748; d. at Paris, 17 September, 1836. In 1765 he went to his uncle Bernard at Paris, where he first studied medicine. However, after he was appointed in 1770 professor and demonstrator at the Jardin du Roi in place of Lemon- nier, he applied himself entirely to botany. In 1804 he was made professor of botany in the medical faculty at Paris, where he lectured until 1826. His memoir on the classification of the family of Ranunculaceae (1773) led to his election to the Academy of Sciences. He adopted his uncle Bernard's ideas concerning the natural system, expanded them, gave them a theoreti- cal basis, and applied them practically to the different families. All our knowledge concerning the natural system of his uncle we owe to him; consequently it is not possible to make a clear distinction between the work of the two men. As early as 1774, during the lifetime of the uncle, appeared the treatise "Exposi- tion d'un nouvel Ordre des Plantes, adopte dans les demonstrations du Jardin royal", in the "M6m. de I'Acad. des Sciences" (1774), 175-97. His chief work, the result of many years study on the same subject, was entitled "Genera plantarum secundum ordines naturales disposita, juxta methodum in horto Regio Parisiensi exaratum anno 1774" (Paris, 1789). His work has remained the basis of all advance in the nat- ural system of plant classification. It greatly influ- enced investigators in France, especially Cuvier and de Candolle. At a later date it also affected the German and English investigators, who had been at first sus- picious of it as a product of the French Revolution (from 1789) and were extreme adherents of the Lin- niean system. Even more vigorously than his uncle Bernard he upholds the theory of subordination or un- equal value of the characteristics of plants, according to which certain characteristic signs have a more gen- eral and comprehensive importance than others. The characteristics are " weighed, not simply mechanically counted" (pesis et non comptes). Once ascertained, these essential characteristics are to be used like the chief fossils in geology, in order to assign plants to a definite group. It is true that in the application this principle frequently leads to false results. Antoine- Laurent gave to the three main groups of the original classification of his uncle the names of Acotyledon, Monocotyledon, and Dicotyledon, and divided them into fifteen classes, containing in all one hundred fami- lies. A most important fact is that he sought out and clearly defined the characteristics of families, largely indeed in later treatises. In the period, beginning in 1789, of the French Revolution, it may be said in brief that with other scholars he reorganized the Natural History Museum at Paris in 1790, and in 1808 was appointed by Napoleon counsellor of the university. During the years 1789-1802 he puljlishcd no botani- cal works. It was not until the "Annales" and "Memoires" of the Natural History Museum were fouiuled that there began for him a new era of intense activity in investigation. He wrote for these publica- tions, 1802-20, a very large numli(>r of memoirs and notes on individual species or genera, and especially monographs on numerous families. He was led