1922.] ‘« Renal Portal’”’ System. 125 
“normal” kidney as 5 : 6; in the second experiment as 4: 
and the third experiment as 45:6. These results saeeticken are 
similar to the chloride strength results and doubtless the same 
explanation applies to both—indigo-carmine dye apparently. 
acts like chloride, increase of fluid pressure increasing its 
percentage in the urine. 
Some Theoretical Considerations. 
In Parts I, II, HI I have proved conclusively both that 
the so-called “ renal portal ”’ system is devoid of function and that 
it is distinct and separate from the intertubular plexus. It 
previous paper (44) a raison d’étre for the ‘‘ renal portal 
system. This, stated briefly, is to e found in the confingd 
active and like all other capillarizations, penetrates the tissue 
of the organ “a be supplied for functional purposes, but in the 
case of the “‘ renal portal ” system the blood tissue is passive and 
itself bencinas: fenaetcated by the adjacent organ apparently for 
mechanical reasons only). The successive antero-posterior 
dévelopients of the kidney (pro-, meso-and meta-nephroi) 
relatively far apart anteriorly and near the median line 
posteriorly, and the kidneys thus apparently select the site of 
the veins because et | is most easy in this position— 
there is more s In the Mammals and Birds, on the other 
hand, with ‘iieeeta hind limbs, the limb veins need direct and 
easy access to the -caval, and the kidneys in such active 
e post 
animals become greatly enlarged relative to the rest of the 
body, ! and for both these reasons the development of << renal 
portal * system is impossible. 
We conclude then that the vascular supply of the kidney 
is identical throughout the Vertebrate series and that it is the 
arterial supply alone which is utilized for urine secretion. This 

. : Wt. of Body. 
} 
I have determined the ratio Wt. of both Kidney 
e — of all classes of Vertebrates. The prin’ fo will be published 
ae a _ 2 large numbers 
