90 Journal of the Asiatic Society of Bengal. |N.S., XVII, 
the flow (volume of fluid passed in a unit of time) of fluid in 
each renal afferent vein is about 1/3, and, to avoid all pos- 
at not more than 1/4, of the flow through the aorta; and (2) 
that the flow through each renal afferent vein is about three 
times the flow through the renal arteries supplying each 
kidney, i.e. the venous supply of the kidney of the Indian 
frog is about three times as great as the arterial supply. To 
reproduce these relative flows in perfusion experiments in the 
Indian frog (average specimens of which are about ten times 
the weight of an average specimen of Rana temporaria) I 
selected a cannula for the aorta with a flow of about 70 c.c. 
per minute at 24 cms. pressure, and two cannulae for the two 
renal afferent veins, each with a flow of about 10-12 c.c. per 
minute at 24 cms. pressure. Using these cannulae | raised 
the aortic perfusion bottle to 24 cms. pressure, and adjusted 
the heights of the two renal afferent vein perfusion bottles 
(usually between 4 cms. and 7 cms.) so as to give equal flows, 
each approximately one quarter of the flow from the aortic 
bottle. Apart from the calibres of the cannula nozzles, I 
found that, to obtain correct relative flows, the heights of the 
renal afferent vein perfusion bottles had also to be adjusted 
in connection with the osmotic pressure of the renal afferent 
vein fluid relative to that of the arterial fluid (see Appendix C), 
and with the size of the frog’s body '—the greater the osmotic | 
pressure of the renal afferent vein fluid relative to that of the 
arterial fluid and the larger the frog, the more “ head” of fluid 
required in the renal afferent vein bottles. 
by the facts that most of the results obtained from perfusion 
experiments have been confirmed by those obtained from 
experiments on the living animal, and that the urine secreted 
by the kidneys in these experiments always differed in total 
nitrogen and chloride strengths from the perfusing fluid, i.e. 
the urine was not a mere filtrate. The investigations of 
Vernon (41), which prove that the mammalian kidney can 

' Ican only explain this by supposing (the aortic bottle pressure 
(which are essentially pressure reducers) and the renal 
inca on — ied the leg capillaries—the result being that the flow 
if e renal afferent vein = . to that 
through the intertubular leitine becomes excessive relative to 
