Geoffroy Saint-Hilaire. I. Etienne. a French zoologist, born in Etampes, April 15, 1772, died in Paris, June 19, 1844. He was educated for an ecclesiastical life, but evinced a taste for natural philosophy, and had gained some proficiency as a mineralogist when the revolution broke out. Hauy having been incarcerated as a recusant priest, his pupil managed to procure his liberation, and at the peril of his life be rescued 12 other priests from prison, on the very eve of the massacre of September, 1792. A few months later he was appointed to a subordinate office in the jardin des plantes, and in 1793, on the reorganization of this establishment under the name of museum of natural history, he was made professor of zoology. Through his exertions, the old specimens were put in order, new ones were procured, and the zoological collections became the richest in the world. In 1795 he welcomed to Paris George Cuvier, then entirely unknown to fame. In concert they pursued researches in comparative anatomy, and at that time each of them had but a faint conception of the opposite systems upon which they were to separate 35 years later.

In 1798 Geoffroy was one of the scientific commission that accompanied Bonaparte to Egypt; remaining there until the surrender of Alexandria in 1801, he was one of the founders and most active members of the Egyptian institute, thoroughly explored the country, gathered valuable collections of natural specimens, and carried them to France. The papers in which he described these specimens attracted general attention, and resulted in his election to the academy of sciences in 1807. In 1809 he was appointed professor of zoology in the faculty of science at Paris, which post he filled for years simultaneously with that at the museum. From 1812 to 1815 his scientific occupations were partly interrupted by sickness and political activity, He was a member of the chamber of deputies during the hundred days; but on the second restoration he returned to his wonted pursuits. He applied himself to demonstrating the principle of which Buffon and Goethe had had but a glimpse, the unity of organic composition among the various kinds of animals; and he founded what he called the theory of analogues." The unity of composition, according to his idea, is the law of identity in the materials composing the organs of animals of different families, and which, although infinitely varying in shape, bulk, and use, are still the same in all, and discover a single plan; while the theory of analogues is the method through which the unity of composition is demonstrated.

As to the unequal sizes among the various creatures, and monstrosities in individuals, they are explained by the principle of arrest of development. These principles, at once bold and original, were in direct contradiction to those which Cuvier had adopted as the basis of his comparative anatomy; and this opposition, which had been silently going on for years, at last broke out openly, July, 1830, in the sittings of the academy of sciences. The contest between the two illustrious champions caused a deep sensation throughout the scientific world of Europe. Notwithstanding the superiority of Cuvier as an orator and scientific expounder, the victory was left undecided, and many among the learned sided with Geoffroy, whom Goethe hailed as an apostle of the true synthetic doctrine. Whatever may have been his faults, he is incontrovertibly, after Cuvier, one of the most important contributors to the advancement of the science and philosophy of natural history. His views contain much of the transcendental element of the German physio-philosophers, and, if carried to their legitimate conclusions, lead to doctrines directly opposed to the prevalent philosophy of final causes. (See Philosophical Anatomy.) Among his numerous works and papers, which embrace nearly all branches of zoology, we refer specially to the following: Philosophie anatomique (2 vols. 8vo, 1818-'22), which contains the exposition of his doctrine; Prin-cipes de la philosophie zoologique (8vo, 1830), which gives a synopsis of his discussions with Cuvier; Etudes progressives d'un naturaliste (4to, 1835); Notions synthetiqucs de philosophie naturelle(8vo, 1838); Fragments oiographiques (8vo, 1838); Histoire naturelledes mammiferes, in conjunction with Frederic Cuvier (fol., 1820-42). He also contributed to several great publications, and especially to the description of Egypt by the scientific commission of which he was a member.

It was not till 1840 that he gave up active life on account of blindness; a few months later he had a stroke of paralysis; but he withstood his last sufferings with admirable equanimity. His eulogy was delivered by M. Flourens in 1852 at the academy of sciences. An excellent biography had been previously published by his son under the title Vie, travaux et doctrine scientifique d'Etienne Geoffroy Saint-Hilaire (Paris, 1847).

II. Isidore, a French zoologist, son of the preceding, born in Paris, Dec. 16, 1805, died there, Nov. 10, 1861. Under the direction of his father he devoted himself to natural philosophy, became assistant naturalist at the museum when only 19 years old, and in 1830 delivered zoological lectures in that institution as his father's substitute. Three years later he was elected to the academy of sciences. He was then publishing a great work in which he enlarged upon a branch of the natural system outlined by his father; this was his Histoire generale et particuliere des anomalies de Vorganisation chez Vhomrne et les animaux, ou traite de teratologic (3 vols. 8vo, with an atlas, 1832-,6). On its completion he was appointed assistant lecturer to his father at the faculty of sciences, afterward filled some important offices in the university, and in 1850 resigned the post of general inspector to resume the chair of zoology, He devoted his leisure to his Histoire naturelle generale des regnes organiqncs, of which but two volumes were published (1854, 1859). He also paid much attention to the domestication of foreign animals in France, as appears from his treatise Domestication et naturalisation des animaux utiles (1854), and advocated the use of horse flesh as food in his Lettrcs sur les substances alimentaircs, etparticulierement sur la viande de cheral (1856).