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Show 334 MR. F. E. BEDDARD OX THE [ Feb. 16. abundance of small ones. From the posterior end of the liver to the mesenteric artery there are 14 gastric arteries, followed by one which, at any rate, chiefly supplies the spleen. There are thus altogether 13 belonging to this series. The first of them is distinctly larger than any of the preceding hepato-oesophageal vessels. These 11 vessels are really arranged in pairs, one of each pair supplying one side, the other the other side of the stomach. The arteries appear to be in reality all of them paired ; but the arrangement is lost here and there, owing to the dwindling or total disappearance (?) of one or other of the two arteries making up the pair. Were these invariably present the total of the large-sized gastric arteries would have had to be increased by four. The actual facts of arrangement are these :-The series commences with a pair followed by a single artery, to which, however, corresponds on the opposite side of the aorta a very minute branch. Then follows a pair, the peculiarity of which is that the two vessels arise one in front of each other from the same (right) side of the aorta. The next two are a pair, I believe ; but the two arteries arise rather further away from each other than in the case of the previous pair. After this comes a single artery with no fellow that I could see. The next pair also arise some little way apart from each other, but on the same level. Following this is a pair of which the left-hand branch is very minute. The next pair is remarkable for the fact that both trunks arise from a common origin, but shortly after diverge ; the last two trunks may be considered to form a pair, but they arise some little way apart, as is the case with the earlier pair of gastric arteries. The posteriorly arising vessel of this pair supplies, as has already been mentioned, the spleen. Arteries of Intestine.-The 1st, and at the same time the largest, of the arteries supplying the intestine (the shortest, indeed, of all the arteries arising from the aorta) is the superior mesenteric. This artery arises exactly opposite the origin of the 7th of the posterior series of intercostals. It passes first of all under * the 9th intercostal portal, and then gives off a forwardly - running branch which very soon divides into two trunks; of these the posterior is the artery of the fat-body, while the anterior runs as far forward as the spleen and pancreas. The main trunk of the mesenteric then passes over the 10th intercostal portal, and gives off a forwardly-running branch, which passes under the main portal trunk and then gives off three branches to the intestine. The main trunk of the superior mesenteric continues its course along the intestine, giving off branches at more or less regular intervals. Ultimately it becomes continuous with the posterior mesenteric. This artery arises from the aorta between the 34th and 35th of the posterior intercostals midway between the two testes. It runs to the intestine without branching; arrived at the intestine it divides into two main branches, one of which is continuous anteriorly with the superior mesenteric. The * I. e., as seen when the snake is dissected. |