Anatomes publicae

Johan von Hoorn (1662-1724) was the Swedish-born son of a Dutch businessman. Hoorn studied medicine in Leiden from 1681 to 1690, where he may well have heard of Leeuwenhoek. After further study in Paris, he returned to Stockholm where he advanced the practice of obstetrics, especially the training of midwives.

In 1709 he published Anatomes publicae anno 1705 Stockholmiae habitae lectio tertia sive omnipotentis mirabilia circa generationem humanam, a collection of lectures on the anatomy of human reproduction. On pp. 127-130, he inserted a Latin extract of the second part of Leeuwenhoek's very long Letter 28 of April 25, 1679 to Nehemiah Grew about sperm in a variety of mammals and fish. The letter in all its other published versions had one image, a dog's testicles, which Hoorn did not include.