1922.] ** Renal Portal’’ System. 153 
theory. The fact that Ene diuresis the urine comes to 
ygen consumption) shows no signs of increase 
ove the normal during diuresis due to injection of Ringer’s 
fluid, though the output of urine is greatly increased therefore 
the energy expended in secreting this extra output of urine 
must be due, not to the activity of the kidney (tubule) cells but 
o an external source of energy, viz. the blood pressure in the 
glomerulus, of more value as evidence for glomerular filtration, 
since, as Cushny himself admits, the energy of the kidney is 
devoted to the concentration of the urine constituents and not 
to their mere passage into the lumen of the urinary tubules,' the 
ee process being ci even when the tubule epithelium is 
as shown by the experiments with chromic and picric acids 
D. 51). All the facts in short point to the process rer large- 
ly one of filtration under the conditions named, but it is fil- 
tration through the tubules, not the glomeruli, since no fil- 
tration occurred when the chromic and picric acids were per- 
fused via the aorta. 





‘ The energy spent on excreting water must be very rare since 
iid the CO, output of a a fasting oy was found increased by giving it 
much water, nor was the Oy, intake child influenced by an attert of 
diabetes Pape gy during which she ak eight litres of water a day 
(24, p. 262). 
P The rfusion experiments of Miss Cullis (6-) on frogs are some- 
times referred to as affording definite evidence o cidtipesbnes of water by 
the glomeruli. Thus she states, ‘‘ There is no doubt that under all ordi- 
, , h 
