Letter, from Antoni van Leeuwenhoek to the Royal Society, dated at Delft Signed autograph In response to Martin Lister's objections against Leeuwenhoek's theory on generation, he compares sperm to an apple pip from which a tree grows, ie that sperm have to reproduce Read to the Royal Society on 28 June 1699 English translation see EL/L3/9 Transcribed in JBO/10/134 Transcribed and translated in 'Alle de brieven van Antoni van Leeuwenhoek', edited, illustrated and annotated by Committee of Dutch Scientists, vol 12, p 311 23 June 1699