Wrote Letter 50 of 1686-05-14 (AB 92) to Members of the Royal Society

May 14, 1686
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Leeuwenhoek's summary

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

Ontledingen en Ontdekkingen, van de Galnooten, dat deselvige geen vrugt van den Eyken-Boom en konnen genaamt werden, door dien dat hare wasdom alleen veroorzaakt werd, om dat zeker soort van kleine wormkens (die van Vliegen voortkomen, en weder in vliegen veranderen) de Eyke-bladeren doorknagen; uit welke doorknaginge, dan de Galnooten wassen: en soo groeyen ook de Distel-Nooten op de Distels. Van het begin van de planten in de Castanje en Okkernoot, en hoe deselve door strengen haar eerste voedsel of grootwerdinge genieten, gelijk de Dieren in de Baar-moeders doen enz.

Dissections and discoveries of the gall nuts, that of the same cannot be called the fruit of the oak tree, through which only its growth is caused, in order that a certain type of small worms (that come forth from flies, and in turn change into flies) chew through the oak leaves; from which chewing through, the gall nut grows: and so grows also the thistle nut on thistles. Of the beginning of plants in the chestnut and walnut, and how the same enjoy their first nourishment or growth, as do animals in the womb, etc.

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 ten quarto pages, written by a copyist and signed by Leeuwenhoek, is preserved at the Royal Society (MS. 1912. L 2. 3.).


The original drawings are lost. The scans here came from Opera Omnia, the 1722 fourth edition of Arcana Naturae Microscopiorum.

In the text, Leeuwenhoek noted "I have thought fit to have drawings made of the gall-nuts as they grow on the leaves, and shown here in fig. 1." He did not say anything more about who drew the figures, but all of them with the exception perhaps of Fig. 3 and Fig. 4 seem beyond Leeuwenhoek's skills.

He spoke of collecting his gall nuts and thistle nuts from the nearby Haagse Bos. It was a five-mile trip via the regular Delft-Den Haag ferry service.

However, the gallnuts that illustrated this letter, twice the size of the local specimens, were imported from Aleppo.

The mezzotint portrait of Leeuwenhoek by Johannes Verkolje, dated 1686, had the gallnuts (detail on right; click to enlarge) in Fig. 1 on the worktable in front of Leeuwenhoek. Note also that Leeuwenhoek is holding a wide magnifying glass with three lenses.