 Lamarck’s theory of species transformism emerged gradually in his annual Muséum lectures on the “animals without vertebrae” that commenced in 1794. As the new occupant of the Chair dedicated to this vast array of forms, Lamarck undertook in 1794 a massive reorganization of the Muséum collections of these animals. To accomplish this, he adapted for their taxonomic organization the method of arrangement of the plant groups he had developed in his earlier work on French botany (1778), created during his formative years when he worked in the Jardin as a botanist. In this early botanical work he had ordered groups serially from most complex to most simple. Lamarck then adopted a similar method for his initial arrangement of the invertebrate groups of animals.