When the ligature is placed immediately below a collateral branch of considerable size, a bloody coagulum is not formed, though adhesion may occur; but if the excited action should extend to the collateral branch, and its canal become thereby obliterated, a coagulum is speedily deposited. In consequence of the enlargement of the anastomosing branches, and the increasing circulation in them, pulsation generally returns in the tumour, to a slight degree, some days after the operation. This, however, is by no means a sign that the operation has been ineffectual; for the renewed pulsation almost always disappears in the course of a very short time. In one instance only have I found it assume a more permanent and troublesome aspect; in that case, it recurred about ten months after the performance of the operation, but speedily disappeared under the careful use of a compress and bandage. On account of the aneurismal diathesis, it occasionally happens, that after the cure of one aneurism, another appears in a different situation; in two instances, I operated on both thighs, at a considerable interval, successively and successfully, for popliteal aneurism, in the same patients.[17] When the tumour is so situated as not to admit of the application of a ligature between it and the heart, it has been proposed to place the ligature on the distal side of the aneurism, upon the supposition that coagulation will occur within the sac in this case as after the common operation.[18] The practice has been made trial of, but its expediency appears very doubtful; neither has the success attendant upon it been such as is generally supposed: the _post mortem_ examinations have been very unsatisfactory in some of the cases. The application, indeed, of a ligature in that situation can seldom be of any advantage, the artery being already obliterated, in aneurisms of some standing, a long way beneath the tumour; and it is, perhaps, from this circumstance that, in such operations, great difficulty has been experienced in securing the vessel, and that it has been thought necessary even to pass a needle under a thick mass, somewhat in the situation of the artery. It would appear, in some instances, that the artery when pervious had even remained untouched, not being even exposed by the burrowing process employed by some of the operators; and that if any vessel was tied, it was not the trunk in which the disease existed. It would appear that a very correct diagnosis had not been formed in some of the cases. [Illustration]