Ontogeny
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Ontogeny is the origination and development of an organism, usually from the time of fertilization of the egg to adult. The term can also be used to refer to the study of the entirety of an organism's
Parts of a human embryo
Process of zygote to gastrula in development
Germ layers and what tissues they become in humans
Ernst Haeckel, Anthropogenie.
Recapitulation theory
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The theory of recapitulation, also called the biogenetic law or embryological parallelism— usually summarized as "ontogeny recapitulates phylogeny"— is a historical hypothesis that the development of
Ontogeny
…developmental (i.e., ontogenetic) processes can influence subsequent evolutionary (e.g., phylogenetic) processes (see evolutionary developmental biology and recapitulation theory), individual organisms develop (ontogeny), while species evolve (phylogeny). Ontogeny, embryology and developmental biology are closely related studies…
George Romanes's 1892 copy of Ernst Haeckel's controversial embryo drawings
Drawing by Wilhelm His of chick brain compared to folded rubber tube, 1874. Ag (Anlage) = Optic lobes, matching bulges in rubber tube.
Darwin's finches by Gould