Wrote Letter 49 of 1686-04-02 (AB 90) to Members of the Royal Society

April 2, 1686
Standard reference information
Cole's number: 
AB/CL number: 
AB/CL volume: 
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 maaksel van het Been; van de Basten van Boomen; van de Huyd, ende van de Schobbens; van de uytwasemende vochtigheden uyt ons Lighaam, ende van een afschilferend Deeltje van de Huyd.

Analyses and discoveries, of the structure of bone; of the bark of trees; of the skin, and of scales; of the moisture evaporating from our body, and of a little peeling piece of skin.

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 sixteen quarto pages, written and signed by Leeuwenhoek, is preserved at the Royal Society (MS. 1910. L 2. 1.).


The original drawings are lost. The scans on the left sidebar came from the 1686 first edition of Cinnaber Naturalis. The four figures are displayed here as two pairs of figures to preserve the scale. Leeuwenhoek wrote:

I have also drawn, as far as I was able, a small piece of bone from an ox's shank, just as it was before a microscope, as shown here in fig. 1, ABCD; which piece, to my naked eye, is as large as the spot shown in fig. 2.

Similarly, for the piece of peeling skin that he took from his nose, Leeuwenhoek wrote:

And in order to indicate the shape of such a peeling particle I have thought fit to make a drawing of the same, so as to demonstrate the way these cone-shaped parts have accumulated in such a tiny spot; the more so since I have never before been able to observe them, either on my body, when my uppermost skin peeled off, nor in people whose illness consists of a peeling skin.

Fig. 3 is the peeling particle of the uppermost skin, the size in which it appeared to my naked eye. Fig. 4, ABCD, is the same, as I saw it through the microscope.

Alle de Brieven / Collected Letters noted (vol. 6, p. 43):

In the manuscript - but not in either A, B or C - two rectangles have been drawn at the bottom of the letter; one of these contains the words: ‘A cotton seed cut into 24 round slices’, and the other: ‘9 seeds of the cotton tree, from which the membranes have been removed, and the leaves separated’.