Etymology: L, re + capitulum, small head
the notion, formulated by German naturalist Ernst Heinrich Haeckel (1834-1919), that an organism during the course of embryonic development passes through stages that resemble the structural form of species from which it evolved. It is summarized by the statement "ontogeny recapitulates phylogeny." The concept is now regarded as an oversimplification. Also called biogenetic law, Haeckel's law.