1) Previous formation 2) Theory 3) Theory of preformation 
• (n.) An old theory of the preexistence of germs. Cf. Embo/tement.
Pre`for·ma'tion noun (Biol.) An old theory of the preëxistence of germs. Confer Emboîtement . 
Type: Term Pronunciation: prē′fōr-mā′shŭn See: preformation theory
[n] - 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 noun 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
previous formation. · (formerly) the theory that the individual, with all its parts, preexists in the germ cell and grows from microscopic to normal proportions during embryogenesis (opposed to epigenesis).