Siewert Centen wrote Letter L-417 of 7 February 1704 to Leeuwenhoek about cochineal's origin in a plant, not an insect
This letter is known only by reference in another letter.
After reading L.’s observations about how cochineal comes from an insect, Amsterdam merchant Siewert Centen writes a seven-paragraph letter explaining why cochineal must come from a plant, not an insect.
According to the Remarks and footnotes to Letter 248 L-422 of 21 March 1704, Collected Letters, vol. 14, the copy of this letter in the University Library, Leiden, gives Siewert Centen as the name of the merchant that Leeuwenhoek omitted here, as was his custom. Centen probably read Leeuwenhoek's letter about cochineal, Letter L-194 of 28 November 1687 to the Royal Society in Dutch in Vervolg der Brieven, published in 1687 by Cornelis Boutesteyn in Leiden. If he read Latin, he could have read it in Continuatio epistolarum, published in 1689, also by Boutesteyn in Leiden. It was not published in Philosophical Transactions.
The present letter initiates a brief exchange of letters, followed by Leeuwenhoek’s reply, Letter L-419 of later in February, and Centen’s response to that, Letter L-420 of late February or early March 1704.
The Mennonite Centen married Johanna Bruyn in 1695, and they had three children in the years before he wrote to Leeuwenhoek.
Letter L-422 of 21 March 1704 to the Royal Society
Mr...., merchant in Amsterdam, writes to me a very kind letter, dated the 7th of February last, in which he says that he has also found in my researches what I state about the cochineal, and requests me to read his remarks, which he sets down in seven paragraphs, all of which I will not repeat, because it would take me too long; I will therefore only mention a few of his remarks.
The said gentleman says that it appears impossible, and altogether incredible, that they should be little animals with wings, head, and legs, not only if one considers the great number brought from America in every fleet; for it will be found that two of the largest grains, eight of the medium-sized sort, and 20 small ones hardly weigh one ase, and therefore in a pound-weight there will be 102,400, large and small. Thus, when in a fleet there arrive 200,000 pounds, what an enormous number must that be. Secondly, what a large number of people (able to do this) would be required to divest those little animals, in the period in which they live, of their heads, legs, wing-cases, and wings, and to dissect them, so that the said gentleman believes that it is a fruit or growth of some plant.
