Christiaan Huygens wrote to Nehemiah Grew about seeing the sperm in human semen
Huygens noted in this letter to Grew that the sperm he saw had been discovered by Johannes Ham, not Leeuwenhoek.
Letter 2125 in Huygens's Oeuvres Completes, volume 8, p. 76.
Birch's History, vol. III, p. 415
A third letter in Latin was read from Mons. Huygens to Dr. Grew, dated at the Hague, 6th June 1678 N.S. in answer to the Dr's letter, and expressing Mons Huygens's desire to be informed of the inventions and proceedings of the Society, as he had formerly been by Mr. Oldenburg, and promising in return to communicate to them whatever he should think worthu of their notice. He added, that he had of late employed some thoughts about improving microscopes; being prompted thereto by the discovery of those animalcules in semine animale made by one Hammius, a student at Leyden, which animalcules, he, Mons. Huygens, had often seen.
It was ordered, that care should be taken to answer this letter, and to continue this correspondence with Mons. Huygens.
