At age 52, his 25th letter in Philosophical Transactions

April 20, 1685

At age 52, his 25th letter, Letter 43 of 5 January 1685 (AB 82) to the members of the Royal Society, was published in Philosophical Transactions, volume 15, number 170 (April 1685): An Extract of a Letter from Mr. Anthony Leewenhoeck F. of the R. S. to a S. of the R. Society, Dated from Delf, January 5th. 1685.

Because some letters were split into two articles and other articles contained two letters, this article in Philosophical Transactions is the 26th article that Leeuwenhoek had published there.