Wrote Letter 45 of 1685-03-30 (AB 84) to Members of the Royal Society

March 30, 1685
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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 twenty-five quarto pages, written and signed by Leeuwenhoek, is preserved at the Royal Society (MS. 1904. L 1. 75).


The original figures are lost. The scans on the sidebars came from the 1708 third edition of Arcana Naturae Microscopiorum.

Fig. 1 of the dog's uterus was so large that it, along with the much smaller fig. 2 of the dog's fallopian tube, was printed on an unnumbered page by themselves. The inset engraving with figs. 3 and 4 of sperm was printed upside down. The other engraving, also of sperm, figs. 5 and 6, was printed correctly.

Leeuwenhoek described his approach to the figures illustrating his observations:

I furthermore opened the sheath of the uterus, and when it was open, had it drawn by a draughtsman, as also the womb with the supposed egg-nests which others sometimes call the testicles, instructing the draughtsman (teijkenaar) to shorten the length of the sheath and the womb, so that they should take up less space on the paper, but that he should keep the thickness of the womb as it was, and also that he should draw the supposed egg-nests with the glandular particles and vesicles to the actual size as they appeared to him.

I am well aware that this figure will be criticized by those who make it their business to instruct others in anatomy, because the manipulation was performed by unskilled hands; but it must be understood that I am no expert anatomist, having never in my life seen a womb being removed from an animal, except when doing it myself or watching a butcher at work.