Johann Wilhelm von Pfalz-Neuburg, Elector Palatine

visitor and correspondent
Birth or Baptism date: 
April 19, 1658
Death or Burial date: 
June 18, 1716

German noble interested in the arts and science. On 28 June 1695, he visited Leeuwenhoek along with his second wife Anna Maria Ludovica De' Medici and his mother Elisabeth Amelie Magdalena Von Hessen-Darmstadt. They were also accompanied by two court physicians who stayed behind to see more.

The following month, Leeuwenhoek wrote to von Pfalz-Neuburg:

The pleasure which Your Serene Electoral Highness as well as your illustrious companions kindly took in the contemplation of some natural discoveries at the time when I enjoyed the honour of showing them to Your Serene Electoral Highness at my house, as well as the fact that I subsequently showed some of my further observations to Your Serene Electoral Highness's two court physicians and surgeons make me take the liberty to send Your Serene Electoral Highness the following truths about generation, newly discovered by me, hoping that they will not be unwelcome to Your Serene Electoral Highness.

Leeuwenhoek's letter to Pfalz-Neuburg of 1695 September 18 (Letter 157 [95]) was about eggs and sperm in mussels and other shell fish and in lice. Small animals from the water (plankton) serve as food for larger ones. Swan mussels move by means of their feet. Their embryos are incubated in their gills. Leeuwenhoek compared them to  comparison to oysters. Contrary to those who expouse spontaneous generation, Leeuwenhoek discussed his view that organisms do not originate from mud or exhalations.

In Letter 96 of 1695-11-03 (AB 160), Leeuwenhoek continued his discussion of swan mussels. He explained his observation of a number of species of little animals (protozoa) from water taken out of the swan mussels and how the little animals feed and propagate. He included extracts from old letters to Oldenburg and Brouncker.

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