Translation of a letter, from Antoni van Leeuwenhoek to the Royal Society Original letter dated 2 April 1686 Leeuwenhoek answers queries raised from letter dated 12 October 1685 (EL/L1/77) about the structure of cotton seed, the sweat glands of the skin and the slime of fish; examines the eggs of frogs; concerning the structure of bone; observations of the growth of tree bark, and compares this to skin; observes the growth of human skin Original figures now no longer exist Translation of EL/L2/1 1686