Embryology in the Enlightenment

In 1677, Johan Ham and Anton van Leeuwenhoek were the first to see human sperm under a microscope. They mistakenly believed that each sperm carried a tiny human, a 'homunculus', and that the woman contributed nothing. Almost a century later, Lazzaro Spallanzani showed (by carrying out artificial insemination in dogs) that both egg and sperm are needed to create a new life. In 1759, Caspar Wolff proposed that the different parts of a growing baby develop from different layers of cells, which we now know to be correct.

In the seventeenth century, scientists believed that every sperm contained a tiny human. Anne Cooke