Dictionary of Human Evolution and Biology

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Preformation Doctrine

Outdated idea, predating microscopic studies, that organisms exist in a small, preformed state in the germ, and growth (in the absence of development or differentiation) consists of the unfolding of a pre-existing form sometimes called a homunculus. Associated with Italian physiologist Marcello Malpighi (1628-94) and others, replaced historically by blending inheritance and later by Mendelian inheritance. There were two forms of preformation: ovism and animalculism. Aka preformation theory, preformationism.

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