by coagulum before blood had been poured out in such quantity as to effectually prevent the actions of the heart; at a future period the coagulum gives way, and the subsequent effusion is limited only by the pericardial cavity being completely filled. In wounds, hemorrhage is the symptom which most alarms the bystanders, and which demands immediate attention; but, to operate successfully, the surgeon must divest himself of all fear, and learn to look boldly on the open and bleeding mouths of arteries. Effusion of blood ceases spontaneously, even from considerable vessels, on faintness supervening, and thus many lives are saved; but as soon as reaction commences it generally recurs, and may prove fatal, unless proper measures be resorted to. When an artery is divided, its extremity retracts within the sheath, it also contracts, and coagulation occurs; thus the orifice is obstructed, and a temporary barrier formed to further hemorrhage. The tube, however, is permanently closed by effusion of lymph from its orifice, and consolidation of the surrounding parts. The circumstances which follow division of an artery are these:—The immediate effect is retraction of its ends within the investing sheath, and a simultaneous contraction of the coats, so as to diminish the calibre. From the superior orifice there is necessarily a profuse flow of blood, which is discharged through the sheath that formerly enclosed that part of the vessel which has retracted. After considerable effusion of blood, the flow becomes slower and less profuse; particles of blood adhere to those filaments which previously connected the artery to the sheath, but which were lacerated by the sudden retraction of the divided extremity; these particles coagulate, and lessen the canal through which the blood is discharged, whilst they present an irregular surface, on which the blood continues to be deposited and to coagulate; and thus the aperture in the sheath is ultimately closed. This external coagulum is found to commence at the extremity of the artery, where it is of a cylindrical form, and shuts up the mouth of the vessel; it then extends along the canal in the sheath, frequently assuming a conical form; and, if a free discharge has been allowed for the blood, it will terminate at the cut margin of the sheath, otherwise it will be found continuous with the coagulum blocking up the external wound. Also, when hemorrhage has been resisted by the shutting of the external wound, blood is infiltrated into the cellular tissue around the bleeding point, and there coagulates; but this circumstance can be productive of little or no pressure on the parietes of the vessel, so as to assist those other natural means which obstruct it. The flow of blood through the divided vessel being prevented, the circulating fluid necessarily passes through the nearest collateral branches, leaving the blood in the extremity of the larger trunk in a state of