164 Journal of the Asiatic Society of Bengal. [N.S., XVIII, 
-_ ength : thus in one experiment I —— urine say on “i = follow- 
ng nitrogen ee 0-00001 0140 gm 
In of the seven other experiments referred to, ceed of excising 
the packs T tie a into it a wide-mouthed cannula with a short piece of 
rubber tubing attached. So oes as this heart cannula and rubber tubing 
abe “© 30 fluid” o nde streng - 000046 gm. and ‘‘ 46 flui 
a nitrogen at ag 2 0: 73 gm. = eee urine of a nitrogen 
strength of 0-000073 gm.) but on ome: “the en ee = a cannula 
rubber tubing, at the — 46 fluid + was 
being perfused, to from 2 to 4 se above the cael of ‘he ro at once 
obtained urine of a arbi nd strength of 0:000106 gm. and, when indigo- 
carmine was added to the v. fluid, of the color of Sack blue ink ! These 
results show clearly that when the outflow is rringerraeee and the pressure 
in the post-caval, renal ven = eshwork and renal ee. vein ae 
fore increased above scmatat e 46 fu id sees its pre 
actually penetrating ink an abciae, so to speak, the aiorial full 
in the intertubular plexus, with the result that the urine increases in 
nitrogen strength and, when dye is present, becomes dark ave We 
shall see cat oe: (Part III) that increase of pressure ict the i tortabulae 
plexus by itsel} causes nitrogen-weakening of the urine (if the 30 fluid had 
been in the renal afferent vein when the heart cannula tubing was raised, 
the urine would have become 
pore itis sam sone — “ the nitrogen-stronger (and dye-containing) 
nal affere in fluid i the intertubular plexus which produc 
the Ponder vast paeiet: 
all of these experiments, the urine ot hae pm a greater percentage 
of nitogen Reel = arterial fluid when the latter was at 24-26 cms. 
pre experiment I lowered she pdioen bottle to 18 cms, and 
socaiae urine eri a nitrogen strength of 0-000253 gm., the arterial fluid 
being 0-000093 gm. and the 46 fluid 0 0000193 gm. Decrease of pressure 
therefore of nitrogen in the urine. ese fact 
effectually dispose of the notion that ei ‘* urine ’’ of these pine wetha is 
a mere gious and not a true secretio 
In a second Experimental Series ie experiments only differed from 
and ds 



the preniiiies} in that the 30 46 fluids were perfused simultaneously, 
each a —_— one renal afferent vein, and the results erm se 
experi ts) were identical, the sam bee of urine jeer from the t 
kidneys eiag in all cases equal in strength. 
Experiments performed to determine if Potassium ferrocya- 
ide and Potassium iodide behave like the Nitrogen (and 
Indigo-carmine) is the preceding experiments, 
EXPERIMENT 1. The aortic perfusion fluid eee of 0°6% saline 
abt 40 c.c. recesarines urine being added to each 2000 c.c., per- 
at 26 cms. pressure, ide — eee the same as those 
pra in the last Series. . were a Faeroe . 
0°00625% The e oxperians was set going at 8-45, and I put Ist 
a pair tubes from 8°50-9°5 
These samples, when mixed with equa 
IL=1°4 e.c. —s volumes of the stock ferric be 
IR=1-3c.¢ solution, were pure yellow in color. 

