From eggs to fossils: epigenesis and transformation of species in Pander's biology.

Christian Heinrich Pander (1794-1865), a Russian scientist of German culture, is known for his epoch-making work in embryology, as well as for his important contributions to palaeontology. Indeed he viewed embryonic development and the history of the earth as two aspects of one and the same essential phenomenon, namely, a perpetual metamorphosis affecting the living world on different scales. He viewed embryology as a gradual, epigenetic transformation (as opposed to preformation) with an intermediary stage, the formation of simple germ-layers. As early as 1821, he argued more generally that species themselves transform under the influence of certain environmental factors. Pander thus embodies the very close link that existed between the triumph of epigenesis and the expansion of transformist theories in the early 19th century.