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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


(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
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.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"
References in periodicals archive ?
74) Preformationists held that the embryo was already an adult in miniature form, and merely depended on its parents and on its environment to provide the essential nutriment to allow it to develop.
72) Preformationists believed that fetal development consisted solely of the "growth or unfolding of pre-existing structures.
Smart's God appears to work in a more flexible, exuberant way than the God of the preformationists, but this too is a question worth exploring further.
These views helped the preformationists hold on to their ideas for almost two more centuries.