Letter, from Antoni van Leeuwenhoek to the Royal Society, dated at Delft Signed autograph Examination of the eggs of silkworms; examination of caterpillar's eggs; observations of human's squinting and a theory for its cause; as a note, Leeuwenhoek adds that he has observed roots of barley grain Original figures no longer exist; engraved figures for publication are attached Transcribed and translated in 'Alle de brieven van Antoni van Leeuwenhoek', edited, illustrated and annotated by Committee of Dutch Scientists, vol 6, p 311 11 July 1687