Wrote Letter L-164 of 1685-09-21 to Anthonie Heinsius about cochineal

September 21, 1685
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Text of an excerpt from the letter in the original Dutch and in English translation from Alle de Brieven. The Collected Letters at the DBNL - De Digitale Bibliotheek voor de Nederlandse Letteren. It was never printed and the manuscript is lost.

We know of this letter to Heinsius and the previous letter of 10 August, both about cochineal, because Leeuwenhoek quoted from both in Letter 60 of November 28, 1687 (AB 105) to Members of the Royal Society.

As regards the Cochineal, I could not possibly conclude, from any of my previous observations, that it consisted of little animals; for there is nothing to be seen in the same that resembles a little animal; and I felt quite certain that, even if it consisted of animalcules, these would be devoured by the mite. But when, after receiving your latest letter, I once again examined two distinct species of cochineal, I was able sufficiently to assure myself, in one of the two, that each tiny grain is a part of a little animal; and that not only the head, and the foremost part, together with the wings, were removed, and the rest retained; but, what is more, that all the legs, and the shell - or that part to which the legs were attached - had been cast off, so that nothing was left except the inside of the abdomen. And I imagined that the whitish substance which we may observe in the fissures of each grain, is a material that serves to guard the cochineal against being eaten up; otherwise the same could not possibly be protected against the mite.

These fissures of each grain of cochineal, I imagine, have been segments of the worm before it changed into a flying creature; and this latter (detail) I have noticed many times since a few days ago, in my investigations in which I am engaged at present; and if the year's season, in relation to the reproduction of insects, were not so far advanced, I have no doubt but I should be able to discover flying creatures that correspond (if not in colour, then in size and structure) to the little animals whose body is called cochineal......