a tiny fully formed individual that (according to the discredited theory of preformation) is supposed to be present in the sperm cell
Hippocrates and Aristotle proposed the idea of what they called pangenes, which they thought were tiny pieces of body parts. They thought that pangenes came together to make up the homunculus, a tiny pre-formed human that people thought grew into a
baby. In the 1600s, the development of the microscope brought the discovery of eggs and sperm. Antonie
van Leeuwenhoek, using a primitive microscope, thought he saw the homunculus curled up in a sperm cell. His followers believed that the homunculus was in the sperm, the
father “planted his seed,” and the
mother just incubated and nourished the homunculus so it grew into a
baby. On the other hand, Regnier de Graaf and his followers thought that they saw the homunculus in the egg, and the presence of semen just somehow stimulated its growth. In the 1800s, a very novel, “radical” idea arose: both
parents contribute to the new
baby, but people (even
Darwin, as he proposed his theory) still believed that these contributions were in the form of pangenes.
