I adore Early Modern Science! Through no fault of their own — since genes hadn’t been discovered but everyone in Europe knew about horrible parasitic body worms — some biologists thought of sex and propagation in very different ways than we do now. For instance, _preformationists_ thought that there were very small people inside either the sperm (as shown here in this drawing from 1695 by Nicholas Hartsoeker) or the egg — it just took a sort of chemistry from the other partner to make the homunculus unfold. Lazzari Spallanzani thought that women’s ova contained the infintesimally small humans, and that semen were just the catalyst needed to get regeneration in gear. In fact, he thought that sperm were wormy parasite-things (because worms wriggle like sperm, after all), and the seminal fluid provided the critical chemical ingredients. In the 1760s, Spallanzani put his ideas to the test by dressing male frogs in teeny pants. (See second photo.) Taffeta turns out to have been the preferred fabric. He let the male frogs go to town with female frogs, collecting the sperm in the pants along the way. The scientific method sort of won the day here, because Spallanzani was forced to admit that without sperm, frog babies couldn’t exist. But he still thought that the long tails of the sperm were wormy/distinct from the sperm heads. And he was still an “ovist,” thinking that the eggs of females contained miniature creatures, ideas in line with other preformationists.
Source(s): Atlas obscura, “Scientists once dressed frogs in tiny pants to study reproduction,”Robert Lamb, Sept 18, 2017. Homunculus from Almamy stock photo. Buzz Hoot Roar original drawing by Bethann Garramin Merkle, www.comnatural.com .
