Letter, from Antoni van Leeuwenhoek to the Royal Society, dated at Delft Signed letter Observing the structure of a cotton seed; comparing cotton seeds with insects' eggs; observing the structure of the embryo of a cottonplant; concerning stones of dates, the structure of clove and nutmeg and the seeds of fruits; concerning the origins of chyle; concerning salt in sweat; experiment to show that sweat on the skin came after drinking wine; denies the existence of sweat pores; further observations of the optic nerve and eye lens; observations of the bile of a roach; concerning the structure of the skin of the eel, bream and perch; observations of human skin; examination of vinegar, lemon juice, sal ammoniac (ammonium chloride); experiments showing the effects of sal ammoniac on vinegar and blood; experiments with sal volatile oleosum; concerning mulberry trees killed by cold weather Original figures now no longer exist English translation see EL/L1/78 Transcribed and translated in 'Alle de brieven van Antoni van Leeuwenhoek', edited, illustrated and annotated by Committee of Dutch Scientists, vol 5, p 277 English extract printed in 'Philosophical Transactions', vol 17, no 205, p 949 LBO/11(1)/45 for English transcription and engravings from 'Philosophical Transactions' 12 October 1685