Explanation

Anton van Leeuwenhoek, co-discovered sperm in 1678, at which time he believed sperm to be parasitic animals living within the semen, coining the name spermatozoa meaning sperm animals. He assumed sperm had nothing to do with reproducing the organism in which they were found. Later, van Leeuwenhoek was under the belief that each sperm contained a preformed embryo. In 1685, van Leeuwenhoek wrote, sperm are seeds (both sperm and semen mean seed) and that the female only provides the nutrient soil in which the seeds are planted. However, van Leeuwenhoek tried for many years and never found performed embryos within the spermatozoa. Nicolas Hartsoeker, the other co-discoverer of sperm, drew a picture of what he hoped to find: a preformed human (homunculus) within each human sperm. Today, there is no question about the role of sperm in the reproductive process.