Bonnet’s theory of generation offered the best synthesis of 18th century ideas of development and remained a leading authority until von Baer. Bonnet believed in the preformation of the embryo. He used many of Haller’s arguments to support his own opinions. J. Needham (No.533) calls him an organicistic preformationist, for his objection to epigenesis lay in the fact that it apparently did not allow for the integration of the organism as a whole.