The really difficult part of the operation now begins: to isolate the vessel from the spine behind, the inferior cava on the right side, and the plexus of nerves in the cellular tissue all round. The cleaning of the vessel must be done in great measure by the finger-nail, and much dexterity will be required to pass the ligature without unnecessarily raising the vessel from its bed, especially as the vessel itself may very possibly be diseased, and the aneurism of the iliac trunk for which the operation is required will displace and confuse the parts, and may have set up adhesive inflammation. _Results._--Operation has been performed at least ten times. By the first method by Sir Astley Cooper and Mr. James; by the second by Drs. Murray and Monteiro, M'Guire, Heron Watson, and Stokes, and Mr. South, and Czerny of Heidelberg. All the cases proved fatal; Dr. Monteiro's survived for ten days, and eventually perished from hæmorrhage; the rest all died at shorter intervals. LIGATURE OF COMMON ILIAC.--_Anatomical Note._--This short thick trunk varies slightly in its relations on the two sides of the body. As the aorta bifurcates on the left side of the body of the fourth lumbar vertebra, the common iliac of the right side would have a longer course to pursue than that on the left, if both ended at corresponding points. However, this is not always the case, as has been pointed out by Mr. Adams of Dublin, as the right common iliac often bifurcates sooner than the left does. With this slight difference, the position of the two vessels is precisely similar, each extending along the brim of the pelvis from the bifurcation of the aorta towards the sacro-iliac synchondrosis for about two inches. Sometimes the division takes place a little higher, even at the junction of the last lumbar vertebra and the sacrum. This variation depends chiefly on the length of the artery, which, as Quain has shown, varies from one inch and a half to more than three inches. The anterior surface of both arteries is covered by the peritoneum, and each is crossed by the ureter just as it bifurcates into its branches. The artery of the right side is in close contact behind with its corresponding vein, which at its upper part projects to the outside, and below to the inner side. The artery of the left side is less involved with its vein, which lies below it, and to the inside. The right is in contact with a coil of ileum, the left with the colon. The inferior mesenteric artery crosses the left one, while to the outside of both, and behind them, lie the sympathetic and obdurator nerves. There are no named branches from the common iliac.