Adriaan Swalmius wrote to Leeuwenhoek about egg shells

August 1, 1717

This letter is lost. It is known only by reference in Leeuwenhoek's Letter 345 [XL] of 19 August 1717, which begins:

From the very kind letter of Your Honour, I have seen that Your Honour, when eating a chicken’s egg, has been thinking about the structure of the hard rind and the little membrane that lies within against the hard rind, etc. In addition, whether maybe I had carried out some investigations with regard to this. Upon this I shall say to Your Honour, that I have not only thought about this but have also attempted, as far as was feasible for me, to put the innate characteristics of the said parts before my eyes. The notes that I have made of this are the following.

Adriaan Swalmius (1689-1747) was a lawyer and notary in Delft as well as in 1741 city attorney (pensionaris) of Schiedam and administrator of the W.I.C. (West Indies Company) office in de Maze (Rotterdam). Leeuwenhoek and his second wife Cornelia Swalmius were the witnesses at Adriaan’s baptism and Leeuwenhoek bequeathed to him an oil portrait of his Uyttenbrouck relatives.

This letter was the only letter that Leeuwenhoek addressed to Swalmius.