preformationist

/ˌpriːfɔːrˈmeɪʃənɪst/
noun
  1. A person who believes that all living things develop from tiny, fully formed versions of themselves that exist from the beginning (a historical biological theory).
    • The preformationist argued that the miniature adult was already present in the egg.
    • In the 18th century, a preformationist would reject the idea of gradual development.
    • Modern biologists no longer agree with the preformationist view of embryonic growth.
adjective
  1. Relating to the belief that organisms develop from preexisting miniature forms.
    • She studied preformationist ideas in her history of science class.
    • Preformationist thinking influenced early debates about reproduction.
    • The preformationist theory was popular before the discovery of epigenesis.
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