Adriaan Swalmius wrote Letter L-555 to Leeuwenhoek sometime in August 1717 to ask whether Leeuwenhoek had studied a chicken’s egg shell and the membrane within it

August 1, 1717
Collected Letters volume: 

This letter is lost. It is known only by reference in Leeuwenhoek's reply.

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 the baptism of Adriaan, the grandson of the brother of Leeuwenhoek’s second wife Cornelia Swalmius. Leeuwenhoek bequeathed to him an oil portrait of his Uyttenbrouck relatives.

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

See Letter L-556 [XL] of 19 August 1717, the only one in which Leeuwenhoek discussed the shells of chickens’ eggs.


Letter L-556 of 19 August 1717 to Swalmius 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.