noun
preformation theory
Historical biological theory that organisms develop from miniature versions of themselves. Contrasts with 後成説 (epigenesis).
See also: 後成説
前成説は、生物の発生に関する古い考え方の一つです。
Preformation theory is one of the old ideas about the development of organisms.
Epigenesis, the opposing theory that organisms develop from undifferentiated material, not preformed miniatures.
From 前 (pre-) + 成 (formation) + 説 (theory). A calque of the Western scientific term 'preformation'.