1922.] Renal Portal’’ System. 103 
ing increased rate of flow of the arterial fluid through the 
glomeruli would soon stop the penetration), it is evident that 
if, us I maintain, the high osmotic pressure of the renal affer- 
ent vein fluid dilates the capillaries of the intertubular plexus, 
then, on account of the resistance of the intertubular plexus 
becoming reduced, the pressure in the glomerular capillaries 
creased osmotic pressure of the renal afferent vein fluid causes di- 
latation of the intertubular plexus capillaries and so increases 
the volume and rate of flow of the fluid in it—with a resulting 
increase of urine of the same composition as that obtained with 
renal afferent vein fluids of lower osmotic preasure : that 
produces the opposite effect by constriction of the intertubu- 
lar plexus capillaries ; that the intertubular plexus is physiologi- 
cally and structurally separate from the renal venous mesh- 
work, and that the tubules secrete the whole of the urine, the 
glomeruli taking no direct part. 
Conclusions and Brief Review. 
I have, in the preceding abstract, stated five a priori 
reasons, all of considerable weight, for regarding the “ renal 
portal’’ system (renal venous meshwork) as devoid of any 
function. If these reasons be accepted as valid, it is practical- 
ly certain that the renal venous meshwork (which after all is 
only a broken-up portion of a purely extraneous structure—an 
adjacent vein returning blood from the hind limb and pelvic 
region) can have no physiological connection with, much less 
form part of, the intertubular plexus of the Amphibian or other 
‘“portal’’ type of kidney. This conclusion is also in accord- 
ance with such well-known facts and considerations as that 
(a) the kidney is in the whole Vertebrate series constructed on 


to raise its osmotic pressure. If it be argued that the high osmotic pres- 
sure of the renal afferent vein fluid dilates the glomerular capillaries in the 
way as I suppose that it dilates the capillaries of the intertubular 
plexus, the reply is that such dilation will reduce the fluid pressure in the 
glomerulus and should therefore, on the hypothesis, diminish the glome- 
rular filtrate: it certainly cannot increase it. 
