1922 .] ‘ Renal Portal” System. 111 
and comparison with the arteries of six normal control R. tem” 
poraria of the same size and sex. If hypertrophy of the rena! 
arteries of the experimental toads has occurred, it is evident 
that it is so small as to be devoid of any significance if regarded 
a compensation for the elimination of the venous supply. 
This will be the more easily realized when we remember that 
the venous supply (as ave determined in the frog Rana 
tigrina (see Appendix A, Part I) to the kidneys is about three 
times the volume of the arterial supply, from which it may be 
deduced that if this venqus blood is of use to the kidneys in 
producing secretion it would need a very considerable amount 
of hypertrophy of the arteries to compensate for its loss. 
The Cause of the Death of the Majority of the Experimental 
Toads and the Regeneration of the Renal Afferent Veins 
in the Toad J 
Ligature of both renal afferent veins in the living toad 
(or frog) necessarily involves considerable perturbations in the 
blood supply of the body. In the first place, since the anterior 
abdominal vein has to convey to the heart all the blood re- 
turned from opi legs and oa ts region : (1) the liver receives 
nearly 3 times |! as much blood as is normally the case—a quan- 
tity which, though vastly in excess of the normal, is yet less than 
the entire quantity of blood normally transmitted to the heart 
by both renal afferent veins and the anterior abdominal, owing 
to the relatively increased resistances offered to the flow of the in- 
creased volume of blood by the distended walls of the anterior 
abdominal vein and of the capillaries of the liver. Again, the 
rate of outflow of blood from the legs eae therefore decreased , 

h 
veins of the hind legs will, with the anterior abdomina 1, become 
greatly Sinise with blood (forming reservoirs), and therefore 
e is so much the less for the heart to receive and therefore 
to pump Soran result being a considerable deficit of blood 
in the whole of the arterial system and therefore a paucity of 
supply to the body in general; (3) the hind legs will receive 
even less fresh blood than other organs owing to the increased 
resistance ue by their already partially-blocked venous 
system ; and (4) the arterial supply to the kidneys will be 
dim inished, as to all other organs, but the kidneys will suffer 
more than other organs because not only are they posteriorly 
more than other organs on a 5 Aree blood #1 sup pply 


This esti ~~ is iecindod on the relative areas in transverse section 
ies from the external diameters) of the renal afferent veins com - 
pared with the iiseriee abdominal (see j ieee D). 
