Wrote Letter L-484 of 1711-12-29 to Anthonie Heinsius to refute an article in Philosophical Transactions; he calculates the quantity of blood propelled by each heartbeat and estimates how often the total blood volume circulates through the body

Leeuwenhoek's self-publications are the source for the summaries of his 165 letters self-published and thus self-numbered letters. This letter was not among them.

Of the letters from April 4, 1702 (AB 237) through June 10, 1712 (AB 294), those letters with scientific observations, including this one, were all addressed to members of the Royal Society and almost all of them were excerpted in Philosophical Transactions.