Illustration of the concept of the homunculus, after a drawing by Nicolaas Hartsoeker in 1694. In the late 17th century, the ovists believed that the egg of a given organism contained a tiny version of that organism. This view persisted until the discovery of spermatozoa by van Leeuwenhoek in 1677. Thereafter, the concept of the homunculus became favoured, where a tiny but complete being existed within spermatozoa (or animalcules as they were then known). The animalculist view was first proposed by Nicolaas Hartsoeker (1656-1725). Debate between the ovists and animalculists continued throughout the 18th century.