Wrote Letter L-162 of 1685-08-10 to Anthonie Heinsius about cochineal

August 10, 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.

This letter is known only by reference in another letter. In this letter, Francis Aston writes to Leeuwenhoek to inform him that his recent letter about the reproduction of trees is received but has not been read to the Society.

We know of this letter to Heinsius and the following letter of September 10, both about cochineal, because Leeuwenhoek quoted from both in Letter L-194 of 28 November 1687 to Members of the Royal Society.

Honoured Sir, etc.: I have made several observations, already ere this, with regard to CochinealGa naar voetnoot1) (which many persons judge to be little animals), and since (receiving) Your Honour's letter I have resumed my examinations, and in all cases found it to be the fruit of a tree, which carries, or produces, within itself more than 100 very tiny oval seeds, each of which seeds is again enclosed in a membrane; but we cannot succeed in observing this unless we have first of all placed the Cochineal in water for some hours. And when they have then been stripped of their skin, we shall be able not only to discover the seeds - which are very soft -, but we shall see that many of them have vesicles around them (which are their first enclosing membrane, and quite twice as large as the seed itself); which vesicles are filled with a fine, fluid red water, while the seed is of a dark red colour. And if we split open such a seed, we cannot conclude but that it consists internally of extremely small globules, which have a red colour.

The remaining part of the cochineal that encloses these small seeds consists of tiny membranes that also have a red colour; except that a little substance in the seeds is without any colour, which (substance) seems to me as if it were oil; and if we wish to imagine the structure of this cochineal as it is internally, I cannot find a better comparison than with a dried black currant, with its seeds and membranes such as the currant contains (leaving aside the (respective) sizes of the currant and the seed); and when I examined the membranes or seeds of which a cochineal consists, as thin as it was possible to me, these tiny, thin parts had, so to speak, no colour whatever....