 Revisions of the third point constitute the most significant change in these five points after 1809, although the connection of these changes to Lamarck’s original theory of transformism remains unclear. Both in the diagram supplied as an Appendix to Part I of the Philosophie Zoologique (1809) and in the Introductory Discourse to the later Histoire naturelle des animaux sans vertèbres (1815), Lamarck presented a branching image of group development. Likely responding to criticisms by his younger colleague Georges Cuvier that were directed at the concept of linear relationships of groups (see below), Lamarck admitted a more complex branching pattern of group relations, with some showing independent lineages and even different points of origin. This issue was not, however, developed in any theoretical elaboration by Lamarck himself, and has not had significant impact on the historical understanding of Lamarckianism. Some of these elements in Lamarck’s later theory did, however, have some impact on British readings (Sloan 1997).