The biogenetic law is also known as the recapitulation theory, or the law of recapitulation. The biogenetic law is epitomized in Ernst Haeckel's (1834-1919) phrase "ontogeny recapitulates phylogeny." However, the biogentic law is based on the law of corresponding stages established by Karl Ernst von Baer (1792-1876), one of the founders of modern embryology.

In the course of his comparative studies of embryological development, von Baer discovered the mammalian ovum and the notochord, a transient embryonic structure in vertebrate embryos that eventually develops into the backbone. Von Baer also formulated a powerful descriptive generalization, which he referred to as the law of corresponding stages. This so-called law essentially states that during development the embryo of a higher animal passes through stages that resemble stages in the development of lower animals. As formulated by von Baer, the original law of corresponding stages was associated with four descriptive...