High Quality Content by WIKIPEDIA articles! In the history of biology, preformationism (or preformism) is either the specific contention that all organisms were created at the same time, and that succeeding generations grow from homunculi, animalcules, or other fully formed but miniature versions of themselves that have existed since the beginning of creation, or, later and more generally, the notion (opposed to epigenesis) that the form of living things in some sense preexists their development.