Ovists, including Marcello Malpighi and Jan Swammerdam, argued that a miniature human was housed within each female egg (then recently described by William Harvey); spermists such as Antoni van Leeuwenhoek and Nicolas Hartsoeker argued that each sperm contained little people, or homunculi.
Pinto-Correia avoids a chronological account of the development of preformation, rather structuring the book around each of the challenges to preformation in general, illustrating how ovists and spermists responded differently.
But this overlooks the fact that some of Europe's leading anti-feminists, such as Carl Linnaeus, were ovists
The ovists and the spermists, she insists, were on to something important.
Swammerdam was a committed ovist who deduced from his work on silkworms and other insects that humans existed fully formed, albeit in miniature, inside maternal ova.
Another preformationist, an eminent French ovist, found the notion of Descartes's divinely ordered world so exhilarating that he reported experiencing bouts of cardiac arrhythmia just reading about it.
Despite glaring evidence to the contrary (none of the eggs produced during these unions ever developed), Spallanzani remained a confident ovist, declaring that "the fetus exists in this species before the male performs the office of fecundation.
21) By the end of the seventeenth century there were two competing groups in this category of thinkers: the ovists, who argued that the whole embryo existed preformed in the ovary, and the animalculists, who claimed the same for the sperm.
23 Gasking describes how the early preformationists were all ovists (48), but beginning with Leeuwenhoek in 1683 animalculists became increasingly popular (56).