900 ox THE " RENAL-PORTAL " SYSTEM. [Nov. 27, 



Physiol, vol. xxxiv. p. 399) ; but it seems to me certain that the 

 blood must flow 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 veiy 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 venfe renales adve- 

 lientes is, the same as in Rana, on both sides of the body of 

 Pygojius — the infei'ence being that the blood-flow is in the same 

 direction as in Rana. Thirdly, if the blood-flow is posterior in 

 the post-renals of Pygo2nijS, then the vente renales advehentes 

 must be regarded as factors of the post-renal, and the only source 

 fi-om 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 fi-om ? — the arterial blood of the 

 kidney being wholly or largel}' 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 sujjposition that because 

 the post-renals and lateral abdominals terminate anteiiorly by 

 venules in the muscle-substance, therefoi'e 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 

 siniisoidal 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 CentrojjJiorus, I have myself described, in the caudal supra- 

 neural, an undoubted case of this splitting-up of a vein in the 

 parietal muscle*tissue to form a sinusoidal system which is appa- 

 rently purely mechanical in origin.] 



Literatibre, 



1. Beddard, A. P. — " Some Effects of the Ligature of the Renal 



Arteries in the Frog." Jour. Physiol, vol. xxviii., 1902. 



2. Hyrtl. — " Ueber die Injection cler Wirbelthierniere, &c." 



Wiener Akad. Sitzungsb. vol. xlvii (1), 1863. 



3. Johnson in Todd's Cyclopa?dia of Anatomy and Physiology. 



Article " Kidney." 



4. Jourdain, M. S. — " Recherches sur la Veine Porte Renale." 



Annales des Sciences ISI"aturelles, 4th series, vol. xii., 1859. 



5. NussBAUM, M. — " Ueber die Secretion der Niere." Pfldger's 



Archiv, vols. xvi. & xvii., 1878 ; Anat. Anzeig. vol. i., 1886= 



