Lambert van Velthuysen wrote Letter L-079 to Leeuwenhoek about arteries and nerves
In this letter, Utrecht doctor and magistrate Lambert van Velthuysen writes to L. about the arteries and nerves that van Velthuysen mistakenly thought Leeuwenhoek had discovered in blood.
This letter is lost. It is known by reference in Leeuwenhoek's reply, Letter L-083 of 11 May 1679, his first to Van Verthuysen, which refers to "The very courteous and pleasant letter of Your Honour of the 12th of April," so Van Velthuysen must have initiated the correspondence.
This letter is Van Velthuysen’s first to L. His next letter to L. is Letter L-089 of 17 June 1679. His return of L.’s “handwritten letters” indicates earlier correspondence, now lost. See Letter L-083 of 11 May 1679 to Van Velthuysen, n. 8 and n. 9, Collected Letters, vol. 20, for more on L.’s practice of enclosing notes and copies and asking for their return.
Letter 45 L-083 of 11 May 1679 to Lambert van Velthuysen:
The very courteous and pleasant [letter] of Your Honour of the 12th of April, as well as my handwritten letters, have actually reached me in due course. The arteries, nerves etc., which by other people are called fibres, have never been seen by me in blood, but in male semen, so that it has been wrongly understood or read by Your Honour.