Letter, from Antoni van Leeuwenhoek to Francis Aston, dated at Delft Signed autograph Observations of skin inside Leeuwenhoek's mouth and about his eczema, which he believed sudorifics could cure; observations of a child with a skin disease which causes the skin to become scaly (ichthyosis); observations of the intestines where Leeuwenhoek identifies blood vessels and lymph vessels; the effects of vinegar; experiment to demonstrate the adsorption of food nutrients in the intestines; an account of the intestinal wall and peristalsis 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 167 28 December 1683