[175] Ibid. This is repeated from the article in the Annales.

[176] Ibid. “See my Recherches sur les Corps vivans” (Appendix, p. 141).

[177] Discours d’Ouverture du Cours des Animaux sans Vertèbres, prononcé dans le Muséum d’Histoire naturelle en mai 1806. (No imprint. 8o, pp. 108.) Only the most important passages are here translated.

[178] “We know that all the forms of organs compared to the uses of these same organs are always perfectly adapted. But there is a common error in this connection, since it is thought that the forms of organs have caused their functions (en ont amené l’emploi), whereas it is easy to demonstrate by observation that it is the uses (usages) which have given origin to the forms of organs.”

CHAPTER XVII
THE “PHILOSOPHIE ZOOLOGIQUE”

Lamarck’s mature views on the theory of descent comprise a portion of his celebrated Philosophie zoologique. We will let him tell the story of creation by natural causes so far as possible in his own words.

In the avertissement, or preface, he says that his experience has led him to realize that a body of precepts and of principles relating to the study of animals and even applicable to other parts of the natural sciences would now be useful, our knowledge of zoölogical facts having, for about thirty years, made considerable progress.

After referring to the differences in structure and faculties characterizing animals of different groups, he proceeds to outline his theory, and begins by asking:

“How, indeed, can I consider the singular modification in the structure of animals, as we glance over the series from the most perfect to the least perfect, without asking how we can account for a fact so positive and so remarkable—a fact attested to me by so many proofs? Should I not think that nature has successively produced the different living beings by proceeding from the most simple to the most compound; because in ascending the animal scale from the most imperfect up to the most perfect, the organization perfects itself and becomes gradually complicated in a most remarkable way?”