As opposed to "strict" preformationism, it is the notion that "each embryo or organism is gradually produced from an undifferentiated mass by a series of steps and stages during which new parts are added" (Magner 2002, pp.  154).
Contraria ao preformacionismo "estrito", esta teoría baséase na noción de que "cada embrión ou organismo prodúcese gradualmente a partir dunha masa indiferenciada por medio dunha serie de pasos e estadios durante os cales se van engadindo novas partes" (Magner 2002, pp.  154).