1922.] “ Renal Portal’ System. 129 
two dsaras were apparently the only pressures emplo 
these authors, and it is evident that in order to onablidh: their 
conclusion tcieatie: the possibility of perfusing with a pressure 
of intermediate intensity which might have resulted in urine 
secretion without the glomeruli becoming injected should not have 
been excluded. In other words, it is to me certain that the 
not evident to Bainbridge, Menzies and Collins because they did 
not recognize the separateness of the intertubular plexus from 
the renal venous meshw: 
he proof that this interpretation of the results of Bain- 
bridge, Menzies and Collins is the correct one is to be found in 
the results of five of my own experiments on dye injection 
already briefly referred to in Part I . In these experi- 
ments the dye was injected via one renal afferent vein at a 
pressure of not more than 3 or 4 ems. above normal, the arterial 
circulation being in full force, and I obtained distinctly blue 
urine, xamining sections of these kidneys, dye was always 
absent from the glomerular capillaries and capsules though 
present in some of the intertubular capillaries, in the renal ven- 
ous meshwork and in tubule lumina. These results prove con- 
clusively that the tubules secreted the dye, and are much more 
reliable than the experiments of Bainbri sage eae and Collins, 
to when iter orig six ot thes experiments similar to ore of 
Bainbridge, Menzies and Collins and found, as these authors 
say, that almost invariably, when urine was Ae  y a few 

It is also probable that when the narrow sinusoids or rather — 
of < intertubular plexus are empty ae probably contracted, it 
uch more for open ll th oh thea | it does to cause vaihen 
fluid to penetrate into them when y ope 
Hyrtl’s description (26) of the mech openings of the intertubular plexus 
capillaries into — large channels of the renal venous meshwork must be 
borne in min 
