preformation (redirected from preformationist)

pre·for·ma·tion  (prfôr-mshn)

n.

1. The act of shaping or forming in advance; prior formation.

2. A theory popular in the 18th century that all parts of an organism exist completely formed in the germ cell and develop only by increasing in size.

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preformation [ˌpriːfɔːˈmeɪʃən]

n

1. the act of forming in advance; previous formation

2. (Life Sciences & Allied Applications / Biology) Biology the theory, now discredited, that an individual develops by simple enlargement of a fully differentiated egg cell Compare epigenesis [1]

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preformation

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

Thesaurus

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 of preformation 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"