The Royal Society read part of Letter 50 of 1686-05-14 about gall nuts

June 18, 1687

Birch, History, vol IV, p. 541, 8 June 1687 (O.S.) in London:

Part of a letter of Mr. LEEWENHOECK was read concerning the growth of gallnuts, which he found to be excrescencies of oak-leaves occasioned by the laying the eggs of a sort of flies on those leave, which coming to hatch gnaw the ribs or vessels of the leaves, out of the gleeting moisture whereof he conceived these galls to be produced; and that within them there is commonly found a dead fly or worm ingendered therein.