Geoffroy Saint-Hilaire, ÉTIENNE, French zoologist and biologist, was born at Étaples (Seine-et-Oise), 15th April 1772. He was at first destined for the clerical profession, but shortly after beginning his studies at Paris he came into contact with Brisson, who awakened in him a taste for the natural sciences. He subsequently became a pupil of Hainy, Fourcroy, and Daubenton. In June 1793 he was nominated professor of Vertebrate Zoology in the newly-instituted Museum of Natural History at Paris. That same year he commenced the foundation of the celebrated zoological collection at the Jardin des Plantes. The year 1795 is marked by his introduction to his subsequent friend and scientific opponent, Georges Cuvier. In 1798 Geoffroy formed one of the scientific commission that accompanied Bonaparte to Egypt, and he remained in that country until the surrender of Alexandria in 1801. He succeeded in bringing to France valuable collections of natural history specimens; his labours in connection with this expedition led to his election, in 1807, into the Academy of Sciences. In 1808 he was sent by Napoleon to Portugal, to obtain from the collections in that kingdom all the specimens which were wanting in those of France. On his return he was appointed (1809) to the professorship of Zoology in the Faculty of Sciences at Paris. All his important works were published between this date and his death, which took place on 19th June 1844. Throughout almost all his writings we find him endeavouring to establish one great proposition—viz. the unity of plan in organic structure (see EVOLUTION, Vol. IV. p. 481). This was the point on which he and Cuvier mainly differed, Cuvier being a firm believer in the invariability of species, and grouping the Linnean genera under the four divisions of vertebrates, molluscs, articulates, and radiates. Geoffroy also raised teratology or the study of monstrosities and anatomical malformations to the rank of a science, principally in his Philosophie Anatomique (2 vols. 1818–20). In addition to this he wrote Sur l'Unité de Composition Organique (1828); L'Histoire Naturelle des Mammifères (1820–42) with F. Cuvier; Philosophie Zoologique (1830); Études Progressives d'un Naturaliste (1835); besides numerous papers, mostly on comparative anatomy, scattered through magazines. See Life (1847) by his son Isidore, which contains a bibliography of his works; also the Appendix to vol. i. of De Quatrefages's Rambles of a Naturalist (1863).
His son ISIDORE, biologist and naturalist, was born in Paris, 16th December 1805. Educated in natural history by his father, he became assistant-naturalist at the zoological museum in 1824. He too made a special study of teratology, publishing in 1832–37 Histoire des Anomalies de l'Organisation chez l'Homme et les Animaux. As zoological superintendent he was led to study the domestication of foreign animals in France; and the results of his investigations appeared in Domestication et Naturalisation des Animaux Utiles (1854); in the same year he founded the Acclimatisation Society of Paris. In 1838 he proceeded to Bordeaux to organise a faculty of sciences. On the retirement of his father three years later, Isidore was appointed to the vacant chair, which in 1850 he resigned for that of Zoology at the Faculty of Sciences. In 1852 he published the first volume of a great work entitled Histoire Générale des Règnes Organiques, in which he intended to develop the doctrines of his father, but he died at Paris, 10th November 1861, before completing the third volume. He was a strong advocate of the use of horse-flesh as human food, and championed his views in Lettres sur les Substances Alimentaires, et particulièrement sur la Viande de Cheval (1856).