Paper, 'An essay upon the action of a secretion obtained from the medicinal leech on the coagulation of the blood' by John B [Berry] Haycraft Haycraft writes: 'The following is an offshoot from a more extended investigation upon the coagulation of the blood not yet ready for publication. The blood flowing from a leech-bite is not readily stopped, often flowing for upwards of an hour after the animal has been removed. The blood with in the body of the creature remains fluid for an indefinite time; and when ejected it is found to have lost its coagulability. These are facts known to every surgeon, but they have received no explanation.' Annotations in pencil and ink. Subject: Physiology / Haematology Received 28 March 1884. Read 3 April 1884. Communicated by Thomas Lauder Brunton. A version of this paper was published in volume 36 of the Proceedings of the Royal Society as 'On the action of a secretion obtained from the medicinal leech on the coagulation of the blood'. 1884