1772 - 1844

Etienne Geoffroy Saint-Hilaire (April 15, 1772 - June 19, 1844) was a French naturalist who established the principle of "unity of composition". He was a colleague of Jean-Baptiste Lamarck and expanded and defended Lamarck's evolutionary theories. Geoffroy's scientific views had a transcendental flavor (unlike Lamarck's materialistic views). He believed in the underlying unity of organismal structure and the possibility of the transmutation of species. He amassed evidence for his claims through research in comparative anatomy, paleontology, and embryology.

Geoffroy was a synthesizer and contended, in accordance with his theory of unity of structure, that all animals are formed of the same basic structures in differing proportion, numbers or position. He further believed that organs of differing animals had the same general connections, i.e., homologous parts, however they differ in form and size, must remain associated in the same invariable order. With Johann Wolfgang von Goethe he held that there is in nature a law of compensation or balancing of growth, so that if one organ takes on an excess of development, it is at the expense of some other part; and he maintained that, since nature takes no sudden leaps, even organs which are superfluous in any given species, if they have played an important part in other species of the same family, are retained as rudiments.

Geoffroy’s lobster

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