Human sperm were first discovered by a student of Antonij van Leeuwenhoek in 1677 in the city of Delft. The name of the student is not known for certain: he is variously written up as Ludwig Hamm, van Hamm or von Hammen. According to some writers he is a Dutchman, to others a German. One day he brought to the acknowledged master of microscopy, Leeuwenhoek, a bottle containing semen and pointed out that small animals could be seen moving about in the ejaculate. Van Leeuwenhoek went on to study the seminal emissions from a wide range of sick and healthy men; in the semen of them all the odd creatures could be detected. He described his findings to the Royal Society in London
I have seen so excessively great a quantity of living animalcules that I am much astonished by it. I can say without exaggeration that in a bit of matter no longer than a grain of sand more than fifty thousand animalcules were present, whose shape I can compare with nought better than with our river eel. These animalcules move about with uncommon vigour and in some places clustered so thickly together that they formed a single dark mass. After a short time they separated. In fine, these animals astonished my eye more than aught I had seen before.

Of course at the end of the seventeenth century there was still a mystery as to what sperm actually were. Some thought them to be parasites in the seminal fluid – and saliva and urine and other bodily secretions were quickly examined in the search for more sperm. Others thought them coagulating agents.

A student of Leeowenhoek (below, with his microscope) is credited with the first discovery of sperm. Right up to the end of 17th c., male spermatozoa was surrounded by mystery. Right, as it was understood by Uartsoeher (1655 1725).