1922. * Renal Portal’’ System. Y5 
y 
veil is restricted to the renal venous meshwork and does not 
“supply” the tubules and that the presence of in ligo-carmine 
dye in the rena] afferent vein fluid has no effect on the urine, 
yet it is necessary, both in order to emphasize the physio- 
logical apaitness of the “renal portal” system from kidney 
activity, and to bring forward new facts, to describe the results 
of further experiments. 
It is well known that venous blood has a higher osmotic 
p:essure than arterial blood, and it is evident that the reason 
for this in the cases of the renal afferent vein blood and renal 
artery blood is that, during its circulation between the iliac 
_ arteries and the renal afterent veins, the former has added to 
it the nitrogenous waste matter from the tissues of the legs. | 
If we divide the tissues of the body of a frog into (1) those 
which eliminate their waste pope-pagrn matter directly into 
the blood which enters or may enter the two renal afferent 
veins (tissues of legs, thigh region ney posterior portion of the 
back), and (2) those (the tissues of the rest of the’ body) which 
to the latter class of tissues by. B= 3t on then be evident, 
leaving out of consideration the amounts of nitrogenous matter 
abstracted by the kidnevs from the blood in the renal arteries, 
and, we will suppose, from the blood in the renal afferent 
veins, in each cvcle of the circulation, that 
the nitrogen strength of renal artery bloo 
—_——, is represented by 
the nitrogen gaps of renal afferent vein blood 


the formula >ie. the renal afferent vein blood is 
ap; B 
stronger in nitrogen than the renal artery blood by P. Now 
if we assume that P and B are proport tional in value to the 
as roughly correct), all that we have to do in order to ascertain 
the relative strengths of renal artery blood and renal afferent 

vein of one rebel that peptic appeare to the eye to ained a dense 
blue-black, but if i ed in alcohol n be seen that the dye has 
in reali ardly affected at all the colour of the mass of dney 
tissue, only e sinusoids being This effect may in part 
5 
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=r 
= 
3 
Ro 
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ey 
oe 
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parts of the nee cre On the other hand ; 
rrorahos a eat ser is ligatured and the two renal afferent veins 
much m lood than usual, the kidneys become markedly 
darker i in colou 
1 If saline — erfused through the limbs, the saline returning via the 
eae afferent (or antes abdominal) veins will be found to contain an 
reased percentage of nitrogen. 
