This lecture covers the key concepts of embryonic induction, focusing on the experiments by Spemann and Mangold. Topics include the role of the organizer in instructing neighboring cells, the formation of primary and secondary neural plates, and the regulation of patterns in Xenopus embryos before and after gastrulation. The fate map of amphibian blastula, the coordination of germ layer induction with patterning, and the role of Activin as a morphogen are also discussed.