The appearance of the vessel after the application of a ligature above the tumour has been already shown. The obliteration of the sac proceeds, in some cases, very rapidly; it assumes a harder feel, decreases, and disappears; being connected with the vessel by means of a dense impervious chord, to which condition that portion of the artery has been reduced. The anastomosing vessels enlarge more and more, carry blood freely from above to below the ligature, and thence to below the tumour; some even passing to the latter situation directly from above the ligature. Along with the muscular and other branches, the neurilemmal vessels also become enlarged, and compress the nervous filaments; and to this are to be attributed the annoying pains which sometimes occur in a limb after the operation for aneurism. The enlargement of the arteries of the neurilemma can be distinctly shown by dissection. Immediately after the operation, the circulation in the limb cannot be so vigorous as before; its temperature is consequently diminished, and it possesses less power of resisting the influence of stimuli. The limb ought to be kept only moderately warm; for if too much heat be applied, there is a risk of gangrene. The temperature afterwards rises, and soon gets above the natural standard; the blood, from obstruction in the internal parts, being chiefly determined to the surface. After the collateral circulation has been completely established, the limb regains its natural temperature. Secondary hemorrhage is occasionally a consequence of this operation; nor is it to be wondered at, should one ligature only be used, seeing that this is often clumsily applied; the cellular tissue being lacerated, and the vessel detached from its connections by the use of blunt instruments, directors, and silver knives. When many ligatures are employed and foreign substances placed in the wound, the patient can scarcely be expected to escape profuse bleeding. If, however, the operation by single ligature be properly performed, and the coats of the artery be sound at the deligated point, the occurrence of secondary hemorrhage must be rare. It generally supervenes when the ligature is about to separate: at first there is a thin bloody discharge, afterwards the quantity of blood is more copious; it is evacuated at first in a gentle and continued stream, but afterwards _per saltum_, and in profusion. The discharge not unfrequently stops for a short time, but, on the circulation being excited, it again returns; and the patient soon dies, unless active measures be practicable, and immediately resorted to. Compression can be of no use; nor can astringents, nor venesection, which I have actually seen practised in such cases. The application of a ligature betwixt the heart and the open point of the vessel affords the only chance of saving the patient; the surgeon must interfere, and do what is in his power—he cannot look on and see the patient bleed to death.