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Show 336 Ml!. P. B. BEDDARD ON THE [Feb. 16, Renal Arteries. -The anterior (right) kidney commences at a point about opposite to the middle of the posterior testis. That it is the light kidney seems to be shown by the fact that the renal arteries supplying it arise from the right side of the aorta.. It ends about an inch before the termination of the posterior kidney, and is therefore much longer than it. The first renal artery arises from the aorta between the first and second of the testicular arteries ; after this follow seven arteries, which do not arise at regular intervals from each other nor opposite to the corresponding branches to the left kidney. The arteries of the left kidney are at any rate eight in number, so that there must be at least a fairly accurate correspondence in the blood-supply of the twTo kidneys, though I a m unwilling to state that it is absolutely accurate. Testicular and Supra-renal Branches.-The anterior testis is supplied by only a single artery, which is slender and arises from the aorta opposite to about the middle of the testis. It divides at once, on reaching the neighbourhood of the testis, into two branches, one of which runs forwards and the other backwards ; the former is the testicular artery, the latter becomes a longitudinal and very slender vessel which runs along the supra-renal body and vas deferens and is joined by other arterioles arising from the aorta. It gives off, however, first of all a branch to the fat-body which has been already referred to. Whether it also gives off small branches to the testis I do not know. This longitudinal artery receives four branches from the aorta, and then joins the main artery to the fat-body, which latter arises from, the aorta just behind the origin of the first rectal artery (cf p. 335). On the opposite side it is continued on by a branch arising from this same artery. It is reinforced by a twig arising from the aorta near to the inferior mesenteric and by a small twig beyond this. This longitudinal artery has nothing to do with the blood-supply of the posterior testis, but passes underneath the arteries which run to the latter from the aorta. The blood-supply of the posterior testis is much like that of the anterior generative gland, but with some differences. As with the former gonad, three arterioles arise from the aorta in the region of the posterior testis and join a longitudinal vessel ending anteriorly; this longitudinal vessel receives a branch from the aorta just in front of the second rectal artery, and itself ends in the fat-body artery which conies off from the aorta just behind this rectal artery. The longitudinal vessel is, however, continued by branches of both the two divisions of the fat-body artery as well as from a twig arising from the longitudinal artery in front of the testis. There is, indeed, a kind of rete mirabile among these various small twigs. At the commencement of the kidneys both of the longitudinal arteries accompanying the vasa deferentia end in the longitudinal trunks of the kidneys. From this point, or rather from these points, onwards the vasa deferentia are supplied by branches of the kidney-vessels. Corresponding to the branch which arises from |