The “Discours d’ouverture” contains Lamarck’s first published statement of the theory of the inheritance of acquired characteristics. See No. 316.

Lamarck was one of the greatest of the comparative anatomists. This work is considered the greatest exposition of his argument that evolution occurred by the inheritance of characteristics acquired by animals as a result of the use or disuse of organs in response to external stimuli. English translation by H. Elliot, 1914. Digital facsimile of the 1809 edition from Google Books at this link.

An elaborate expansion of Lamarck’s one-volume work with the same title published in Paris, 1801 (No.215.5). As a systematist Lamarck made important contributions to biology. He separated spiders and crustaceans from insects, made advances in the classification of worms and echinoderms, and introduced the classification of animals into vertebrates and invertebrates. The introduction to this work includes Lamarck’s summary of his four laws of evolution. Digital facsimile from the Biodiversity Heritage Library, Internet Archive, at this link.