Letter, from Antoni van Leeuwenhoek to Hans Sloane, dated at Delft Signed autograph Observations of black flies on fruit trees; observations of aphids; comparing the parthenogenetic procreation of aphids with spermatozoa; on the development of the pupae of moths 5 red-chalk figures attached Read to the Royal Society on 27 November 1700 English translation see EL/L3/24 Transcribed in LBO/13/18 Transcribed and translated in 'Alle de brieven van Antoni van Leeuwenhoek', edited, illustrated and annotated by Committee of Dutch Scientists, vol 13, p 199 English translation printed in 'Philosophical Transactions', vol 22, no 266, p 659 26 October 1700