Wrote Letter L-026 of 1675-08-14 to Henry Oldenburg about blood, taste of saps, sugar, and salt, and the mechanics of taste and digestion

August 14, 1675
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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 12 folio pages, written and signed by Leeuwenhoek, is preserved at the Royal Society (MS. 1842. Early Letters L1.15). Oldenburg's English translation is Early Letters L1.12.

An excerpt was published in Philosophical Transactions, vol. 10, no. 117, dated 26 September 1675. See Publication history below.

Leeuwenhoek wrote this letter to Henry Oldenburg about:

Further blood corpuscles during an illness

arum leaves

the sap in plants and its taste

A theory concerning the taste of sugar, salt and manna, based on the structure of the minute particles they contain

manna (from the bark of 'Fraxinus ornus') and its laxative effects

an account of digestion in humans and the effects of poison on the stomach

Many of these observations, he noted, were done at Oldenburg's request.

One of only two letters published in volume 10 of Philosophical Transactions, this one replied to Oldenburg's lost letter L-025 of 12 April 1675, which was itself a reply to Leeuwenhoek's letter L-024 of 26 March 1675

In this August letter, Leeuwenhoek reported his observations of the texture of blood and the parallel role of sap in plants. He also discussed the structure of sugar and salt and the difference in how they taste.