See p. theory.

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pre·for·ma·tion .prē-fȯr-'mā-shən n a now discredited theory in biology that every germ cell contains the organism of its kind fully formed and complete in all its parts and that development involves merely an increase in size from microscopic proportions to those of the adult compare EPIGENESIS
pre·for·ma·tion·ist -shə-nəst n or adj

Medical dictionary. 2011.

Look at other dictionaries:

  • préformation — [ prefɔrmasjɔ̃ ] n. f. • 1710; de pré et formation ♦ Hist. Sc. L une des deux théories biologiques en lutte aux XVIIe et XVIIIe s., selon laquelle l organisme vivant est complètement constitué dans le germe. « La préformation entraînait… …   Encyclopédie Universelle

  • Preformation — Pre for*ma tion, n. (Biol.) An old theory of the pre[ e]xistence of germs. Cf. {Embo[^i]tement}. [1913 Webster] …   The Collaborative International Dictionary of English

  • preformation — [prē΄fôr mā′shən] n. 1. previous formation 2. Biol. a former theory that every germ cell contains every part of the future organism in miniature, development being merely growth in size …   English World dictionary

  • Préformation — Théorie de la préformation Homunculus de Hartsoeker La théorie de la préformation a été formulée pour expliquer le développement embryonnaire par le déploiement de structures préexistantes dans l œuf. Cette théorie s est historiquement opposée à… …   Wikipédia en Français

  • préformation — (pré for ma sion) s. f. Action de préformer. •   La préformation et l évolution des corps organisés sont une des lois les plus générales de la nature, BONNET Contempl. nat. XII, 42 …   Dictionnaire de la Langue Française d'Émile Littré

  • preformation — noun a theory (popular in the 18th century and now discredited) that an individual develops by simple enlargement of a tiny fully formed organism (a homunculus) that exists in the germ cell • Syn: ↑theory of preformation • Derivationally related… …   Useful english dictionary

  • preformation — noun Date: 1732 1. previous formation 2. the now discredited theory that every germ cell contains the organism of its kind fully formed and that development involves merely an increase in size compare epigenesis 1, homunculus 2 • preformationist… …   New Collegiate Dictionary

  • preformation — n. [L. prae, before; forma, shape] The archaic theory that the egg (or sperm or zygote) contains a preformed adult in minature, and only nourishment is required during development …   Dictionary of invertebrate zoology

  • preformation — preformationary, adj. /pree fawr may sheuhn/, n. 1. previous formation. 2. Biol. (formerly) the theory that the individual, with all its parts, preexists in the germ cell and grows from microscopic to normal proportions during embryogenesis… …   Universalium

  • preformation — noun a) Prior formation b) Any early theory that organisms are fully developed when created and just increase in size …   Wiktionary

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