Letter, from Antoni van Leeuwenhoek to the Royal Society, dated at Delft Signed autograph Examination of the brain of a turkey, sheep, ox, and sparrow; measuring blood vessels in the human eye using grains of sand; discussion of moxa, Chinese remedy for gout; observations of lepers in Harlem and examinations of their skin; examination of the skin of eels Original figures now no longer exist Transcribed and translated in 'Alle de brieven van Antoni van Leeuwenhoek', edited, illustrated and annotated by Committee of Dutch Scientists, vol 4, p 253 English extract printed in 'Philosophical Transactions', vol 15, no 168, p 883 25 July 1684