Letter, from Antoni van Leeuwenhoek to Henry Oldenburg, dated at Delft Signed autograph Observations of marrowfats, peas, runners; structure of venous blood from a pregnant woman; explains the transparency in objects; an account of the circulation in leaves and compares it to veins in humans; explains his drawing of a louse's leg Figure of a louse's leg, the vein of an oak leaf and an ink impression of oak leaves Transcribed and translated in 'Alle de brieven van Antoni van Leeuwenhoek', edited, illustrated and annotated by Committee of Dutch Scientists, part 1, p 277 For summary see 'The correspondence of Henry Oldenburg', ed and trans by A Rupert Hall & Marie Boas Hall, vol 11, p 232 B&W photograph of four pages and two drawings, Box 2, IM/005316 26 March 1675