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Show 900 OX THE " RENAL-PORTAL" SYSTEM. [Nov. 27, Physiol, vol. xxxiv. p. 399); but it seems to me certain that the blood must How anteriorly in the main portion of the post-renal and in the anterior abdominal. My reasons are these : In the first place, if the blood-flow in the post-renal is posterior, then this vein should open into the femoral in a very different manner from what it does, since, as Mr. Beddard figures it, the streams of blood in the post-renal and femoral would in such a case be in direct opposition with no adjacent sinuses into which the blood could be forced in consequence of the resulting pressure (cf. the superior and inferior abdominals of the Crayfish among other instances). Secondly, the inclination of the venae renales adve-hentes is, the same as in Rana, on both sides of the body of Pygopus-the inference being that the blood-fiow is in the same direction as in Rana. Thirdly, if the blood-fiow is posterior in the post-renals of Pygopus, then the venae renales advehentes must be regarded as factors of the post-renal, and the only source from which these factors could derive their blood is the arterial supply of the kidney, whence the obvious question : where does the post-caval obtain its blood from ?-the arterial blood of the kidney being wholly or largely abstracted by the factors of the post-renals. Fourthly, the supposition that the blood-flow is posterior in the post-renals is negatived by the small size of the anterior abdominal vein, into which the blood would, in such a case, have to be poured. But extraneous considerations prove that little weight is to be attached to the supposition that because the post-renals and lateral abdominals terminate anteriorly by venules in the muscle-substance, therefore the blood-flow is from the venules to the main trunk. Lewis in the paper before referred to (footnote on p. 889) shows that the contrary is the case in the sinusoidal system of the myocardium-the lumen of the vein being broken up by intrusion of the muscle-tissue in the same manner as the delta system of a river is formed by terrestrial impediments and the stream of fluid being in the same direction in both cases. Further, in the preceding paper on the anatomy of Centrophorus, I have myself described, in the caudal supraneural. an undoubted case of this splitting-up of a vein in the parietal muscle-tissue to form a sinusoidal system which is apparently purely mechanical in origin. ] Literature. 1 . Beddakd, A. P.-" Some Effects of the Ligature of the Renal Arteries in the Frog.'' Jour. Physiol, vol. xxviii., 1902. 2. H y r t l .- " Ueber die Injection der Wirbelthierniere, &c." Wiener Akad. Sitzungsb. vol. xlvii (1), 1863. 3. J ohnson in Todd's Cyclopaedia of Anatomy and Physiology. Article " Kidney." 4. J o u r d a in , M. S.- " Reclierches sur la Yeine Porte Renale." Annales des Sciences Naturelles, 4th series, vol. xii., 1859. 5. N u s sb aum , M_.-" Ueber die Secretion der Niere." Pfliiger's Archiv, vols. xvi. & xvii., 1878 ; Anat. Anzeig. vol. i., 1880( |
