Siewert Centen wrote Letter L-420 in late February or early March 1704 continuing to argue that his further observations contradict Leeuwenhoek's claim that cochineal comes from an insect

March 1, 1704

This letter is known only by reference in another letter.

In this response to L., Centen reports on his own further observations, which contradict Leeuwenhoek’s conclusion that cochineal comes from an animal.

This is the last known letter between Leeuwenhoek and Centen. Their correspondence began with Centen’s Letter L-417 of 7 February 1704 and continued with Leeuwenhoek’s reply, Letter L-419 of later that month.


Letter L-422 of 21 March 1704 to the Royal Society

I sent almost the whole of the aforesaid account, with the figures, to the Amsterdam merchant, in order that he might be able to see what my discoveries were. In return he wrote to me a long letter about it, in which he says that he has also taken as many as 200 particles from a large cochineal grain and after all his observations he was not able to detect any animalcule in the egg, and finally concluded that what I took to be blood vessels of a cochineal animalcule are such parts as we find in cherries, grapes, etc., and what I took to be the shell or membrane of the eggs are the envelopes of seeds.