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.