 Von Baer's laws (embryology)

Von Baer's laws of embryology (or laws of development) are four rules proposed by Karl Ernst von Baer to explain the observed pattern of embryonic development in different species.Von Baer formulated the laws in the book "Über Entwickelungsgeschichte der Thiere" (""On the Developmental History of Animals""), published in 1828, while working at the University of Königsberg.