preformation(redirected from preformationists)
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Related to preformationists: Preformation theory
1. The act of shaping or forming in advance; prior formation.
2. A theory popular in the 1700s that all parts of an organism exist completely formed in the germ cell and develop only by increasing in size.
1. the act of forming in advance; previous formation
2. (Biology) biology the theory, now discredited, that an individual develops by simple enlargement of a fully differentiated egg cell. Compare epigenesis1
pre•for•ma•tion(ˌpri fɔrˈmeɪ ʃən)
1. previous formation.
2. a former biological theory that the individual preexists fully formed in the germ cell and grows from microscopic to normal proportions during the embryo phase.
the theory that germ cells contain every part of the future organism in miniature form, future development being only a matter of increase in size. Cf. epigenesis.See also: Biology
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|Noun||1.||preformation - 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|
theory - a well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena; "theories can incorporate facts and laws and tested hypotheses"; "true in fact and theory"