Theodorus Craanen

Other name: 
Cranen, Kranen, Cranius, Craen
friend and colleague
Death or Burial date: 
February 27, 1688

Craanen, a German mathematician and physician and supporter of the notorious Descartes, taught for many years at Leiden University. Noting in the letter of 1 November 1677 (AB 35) that Craanen had visited him many times, Leeuwenhoek related that Craanen's nephew Johan Ham (later burgemeester of Arnhem) brought him semen from a gonorrhea patient in which Ham had seen what we now call sperm cells. Leeuwenhoek would examine sperm cells for the following four decades.

Did Craanen help Leeuwenhoek develop his ideas based on Descartes' writing? Does Craanen refer to "globules" in his writing?

In 1677, Leeuwenhoek wrote:

the distinguished Professor CRANEN had many times honoured me with a visit, he besought me, in a letter, to demonstrate some of my observations to his kinsman Mr. HAM. On the second occasion when this Mr. HAM visited me, ...

Related images: