1922.] “ Renal Portal”’ System. 179 
renal afferent vein fluid outside certain limits have considerable effect 
both on the rate = flow of fluid through the intertubular plexus and on 
the output of urin 
The opening and geet - the renal afferent veins in the preceding 
periments cannot bes to have any definite e, if any, effe ct on n the 
Bt 
e ete 
the nitrogen stren gths : Losi samples were estimated, the samples were 
of equal strength in three comparisons (Experiments I, 3, 5) and in the re- 
maining fo comparison s (Experiments 2, 3, 4, 7) the ‘‘ shut vein’’ and 
oe one vein’ urines were alternately > stronger 
Finally, it is of some ini ance t sagictedy carefully the chloride (as 
NaCl) strengths of the samples of « aheit ein’ open vein”’ urin 
respectively in the prec seine: experiments 0 on ‘oleate of their theoretical 
significance. In making these comparisons however it is necessary, in orde 
n vein ne sa 
Experiments 7-10, in which, owing to aon ‘sie renal afferent veins being 
cut behind the cannulae, no such difference of Somer occurred in the 
aorta when ni venous supply to the © kidaoys wa t off. 
Comparing so craparci strengths of Ex Sictiroete 2 and 3, in which 
the veins were a t open, with those of Experiments 4 5, in which 
the veins we a gon shut (85 in both of these last experi nts is Omit- 
ted because Shees.a is no O, to balance it), we see that in iapecicnetts 2 and 
3. 
the average sr ee of ‘‘ open vein”’ urine was 0-004261 gm, 
sampl 
(three 
and », ** shut vein’ re »» 0°005077 gm. 
(thr ree » samples) 
and in Experiments 4 and 5 
the ea pita of ‘‘ shut vein” urine was 0-004981 gm. 
(two samples) 
rr >» ‘‘ open vein’ 7 >, 0°005491 gm, 
( two sample es) 
We thus see that it solely depends on whether the experiment is 
started with veins open or sht “A Be: to whether or not the ‘‘ shut vein 
2 and ei 
mc than the ‘open vein” urine not only because of the change 
from the one condition to the other but because of the increase of flvid 
Seale in the aorta due to the shutting of the veins;! . Experi- 
ments 4 and 5, on the other hand, the ‘* shut vein” urine is already 
relatively strong in chloride owing to the se fluid ———. in the aorta 
and when the veins are opened, the only access of strength which the 
urine undergoes is due to the change of cence dion: hence the in- 

! Possibly this factor accounted for the results of Bainbridge, 
Collins and es s (4). 
