Wrote Letter 30 of 1680-04-05 (AB 57) to Robert Hooke

April 5, 1680
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Leeuwenhoek's summary

From both printings of Levende Dierkens and translated into Latin for all of the editions, some re-titled, of Anatomia Seu Interiora Rerum.

Ontledingen en ontdekkingen, Van de Testicul van een Rot, ende Dierkens in deselve; Van de Mossel en Oester; Van Levende Dierkens in het sap dat uit een Wyngaard-rank droop.

Dissections and discoveries, of the testicle of a rat, and little animals in the same; of the mussel and oyster; of living little animals in the sap that dripped from a vineyard shoot.

Text of 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.

The original manuscript on three quarto pages, written and signed by Leeuwenhoek, is preserved at the Royal Society (MS. 1881. L 1. 52).


The figures of a rat's testicle in a jar of water and a little animal that came from it were the only two figures illustrating this letter. The originals were in ink and are preserved in the Royal Society's archives. In the text, these figures appeared together on a separate unnumbered plate in both the Dutch and the Latin editions. The scans on the left sidebar are from the 1686 first edition of Levende Dierkens.

Leeuwenhoek wrote in the letter that he drew Figure 1 "as far as it was feasible to me" (so veel het mij doenlijk was). He had someone else draw the far more complex Fig. 2 for him: "I caused it to be drawn" (ick heb laten afteijckenen).