In the months after it was written, this letter was read in London in two parts at two meetings, the first on June 30/July 7 (O.S./N.S. Birch's History, vol. IV p. 492, 494):
Part of a letter of Mr. Leeuwenhoeck was read, containing his microscopical observations upon the seeds of several Indian plants, shewing how the leaves and the part designed for the root and stem are wrapped up within the said seeds.
Two weeks later, they heard the last part of the letter.
An account of the manner of the propagation of shrimps, in whose eggs the embryo is perfectly formed before exclusion, after the same manner as some sorts of seeds, which contain the whole plants, being part of a letter of Mr. Leeuwenhoeck, was read.
At the end of this letter, Leeuwenhoek concluded:
After the aforementioned observations I do not doubt but that Your Honours will now feel satisfied on this matter, namely, that there exist several Seeds that have nothing else inside them but the beginning of a young plant.
In both March and May preceding this letter, Leeuwenhoek received letters from Edmond Halley, newly elected clerk of the Royal Society and the editor of Philosophical Transactions.
In the second of those cordial letters, dated May 15, Halley wrote that Leeuwenhoek would be receiving a gift from the Royal Society delivered in person by Mr. Colson, about whom nothing else is known. He also had a request:
Several Gentlemen of the Society, who are your admirers, have heard that yr Picture is of late curiously graved have ordered me to desire of you some few prints to adorn their studies, and one for the Societies meeting room, where you will be sure to be in good company, which you shall think fit to send.
In both the opening paragraph and a short postscript, Leeuwenhoek mentioned Colson, his gift, and the portraits that Halley requested.
I have duly received Your Honours' very agreeable letter of 15/25 May, which served only to accompany the token of honour sent me by Your Honours through Mr. Colson.
In that same Missive Your Honours say, among other things: that this token of honour is merely a sign of respect and gratitude for my constant labours. For this generous and undeserved gift of such a beautiful book I am and remain very greatly obliged.
It was, in fact, Willugby's History of Fishes. Leeuwenhoek doesn't mention it by name or later ever indicate that he had read it. However, he wrote this letter only a couple of weeks after the Royal Society decided to send it to him. He was more impressed with how the Royal Society treated the portrait that he sent to them.
I send you herewith some more of my modest observations and arguments, which, I presume to hope, will please Your Honours: Together with a few illustrations; and if ever I should have thought that such a great honour would fall to my lot to have my portrait hung, in the room where the Friends meet, side by side with other ones, I should not have failed to send it; and I must say once again that I feel very greatly obliged to have received from Your Honours so many marks of honour, and I only wish that I had the capabilities to deserve these.
Leeuwenhoek used the word contrefeitsel, which Alle de Brieven / Collected Letters translates as "pictures" but at the time referred specificially to portraits. If Leeuwenhoek sent twelve, they were not oils. Leeuwenhoek must have referred to the mezzotint (right), a newly developed technique that Johannes Verkolje used to make a reverse image of his oil painting and that could be printed in large quantities from the engraved plate. The verse underneath was composed by Constantijn Huygens, who died the following year.
The mezzotint is dated 1686 and Halley had heard of it by May, so it was probably finished in early 1686. Leeuwenhoek would have sat for the original portrait some time in late 1685. Note the gall nuts on the oak leaves in the lower right, specimens discussed in Letter 50 of May 14, 1686.
Halley had also asked, referring to Mr. Colson:
... the Gentleman that has undertaken to deliver it you, is a very knowing & curious person, & ye Society would esteem it an obligation, if you should think fit to let him view in your most incomparable microscope some of those many curiosities, wherewith from time to time you entertain us, so much to our satisfaction.
It was just a year earlier that Halley had dispatched Thomas Molyneaux from Leiden to Delft on a similar mission to look through Leeuwenhoek's lenses, and that had not gone well. Leeuwenhoek does not say whether Mr. Colson was similarly treated.
