1922. | ** Renal Portal”? System. 137 
the intertubular plexus diminishes the nitrogen strength and in- 
creases the chloride strength of theurine. Similar results were 
obtained in three other similar experiments. 
In the first rabbit experiment,'! with D.C. through both 
kidneys, the left kidney secretvd 5-0 c.c. urine in 30 minutes of 
0:00054 gm. nitrogen strength, and the right kidney 2°6 c.c, 
urine of 6-000373 gm. nitrogen strength. The R.C. through the 
right kidney produced in 28 minutes 31°8 c.c. urine, while in the 
same time 1).C. through the left kidney produced 4°75 c.c. urine, 
i.e. R.C. produced 6°6 times as much urine in the same time. 
The R.C, urine (two samples) was 0.000453 gm. and 0:000546 gm. 
nitrogen strength while the D.C. left kidney simultaneously 
secreted urine 0-000693 gm. nitrogen strength. In the second 
experiment R.C. produced 5:6 times as much urine as D.C. and 
similar results were obtained in the two other similar ex peri- 
ments. 
The significance of these results in connection with the 
intertubular capillaries. Now in these reverse current experi- 
ments, the fluid pressure in the glomeruli, when the current is 
reversed, is less than that during arterial perfusion because the 
fluid has first to overcome the resistance offered by the inter- 
intertubular capillaries during the reverse current contain a 
vastly greater volume of fluid than they do during the arterial 
perfusion and they should therefore be more activel absorp- 
tive, and on this account also a less proportion of urine should 
be secreted during the reverse current. But we have seen 


! Both kidneys had had all nerve connections severed so that this 
factor, as regards quantity of wine, was absent. All the renal nerves in 
the frog experi ts, on the other hand, were left intact. 
nother objection which may urged against these experiments 
on the rabbit is that ‘* failure of absorption from overflooding is espscial- 
ly liable to oceur in the rabbit in which absorption is peculiarly ineffec 
tive at the best” (17, p 59). Even allowing for this factor, the excretion 
of the vein-perfused kidney in these experiments should still have been 
ins of more owing to the decreased pressure in the glomeruli, but 
tes an experiment on the rabbit in which, during sulphate 


ed at the rate of 5 c.c. per minute, ven a is rate, according to 
Cushny, the tubules absorbed 40%of the water passing through the kid- 
neys, i.e. t idneys excreted 0°26% of sulphate while the serum only 
contained 0°15%, so that in my experiments absorption should certainly 
have occurred on the neo-Ludwig view. 
