Theoria generationis.

Wolff observed in great detail the early processes of embryonic differentiation. He disposed of the “preformation” theory, substituting his view that the organs are formed from leaf-like (blastodermic) layers. He thus laid the foundation of the “germ-layer” theory of Baer and Pander. His book includes descriptions of the “Wolffian bodies” and “ducts”. Reprinted 1966.