The Aorta gives off numerous large branches to the intestines, the coeliac axis and superior mesenteric being as large as the carotid. These vessels form arches before finally supplying the bowel, but embolism of even a small branch may lead to gangrene of the bowel. Aneurism of the abdominal aorta occurs most frequently where the coeliac and other large vessels are given off. Several anastomoses exist between the visceral branches of the aorta and those of the posterior abdominal parietes in connection writh organs which have a large uncovered posterior surface, such as the liver, kidneys, part of the duodenum, pancreas, ascending and descending colon. The vessels anastomosing with these arc the lower intercostal, lumbar, ilio-lumbar, circumflex iliac, epigastric, and phrenic, and the blood supplied by this anastomosis has been sufficient to nourish the affected organs after embolism of the coeliac axis and mesenteric vessels (Chiene).