SUMMARY. — Goethe's scientific works, like his poetry, represent a synthesis between classicism and romanticism. Here we study this ambivalence in the case of morphology. Two complementary concepts dominate this science with Goethe : type, or common plan, and metamorphosis, variation from this common pattern. These two notions apply to the whole organism as well as to each of its repeated parts, so they correspond to special and serial homologies. Although Goethe defined these concepts in a somewhat imprecise way, indirectly he had a deep influence on nineteenth-century morphology.RÉSUMÉ. — Les travaux scientifiques de Goethe, comme son œuvre poétique, représentent une synthèse entre le classicisme et le romantisme. Nous étudierons ici cett...