A BRIEF-HISTORY OF PREMOLECULAR INDUCTION STUDIES

Induction was recognized by the embryological anatomists of the early nineteenth century, and it was seen to involve interactions between th e component embryonic parts and between the embryo and its environment . In the 1920s, Spemann's laboratory redefined and reinvigorated the c oncept of induction, making it the center of embryology. This concept of induction incorporated both morphogenesis and differentiation. In t he 1930s, studies of embryonic induction merged with those of gradient s to form a world-wide research program that sought to find the molecu lar agents of these phenomena. Work in induction then continued on its own paths, but also stimulated the new field of developmental genetic s.