96 Journal of the Asiatic Society of Bengal. [N.S., XVIII, 
vein blood in excretable nitrogenous matter is to weigh, in 
individual frogs, the masses of tissue which produce P and B 
respectively, viz. the weights of (1) the legs, medio-dorsal 
trunk muscles and skin, and the posterior part of the vertebral 
column; and (2) the rest of the body. These two weights— 
(1) and (2}—were approximately determined in eight normal 
P+B 3 
2P+B™ 46 

female Rana tigrina, with the average result that 
through the renal afferent vein or veins was made osmotically 
equal in strength to the 46 fluid by the addition of a little 
times (90) as great as that of the arterial fluid (30), though 
the urine was produced in greater quantity when the nitrogen 
all these experiments, with the “ pressure head” in the arterial 
perfusion bottle at 24 cms., the urine contained a greater 
percentage of nitrogen than the arterial] fluid (proof that the 
** urine 2 was nota mere filtrate). In one experiment I lowered 
the aortic bottle to 18 cms. and obtained urine of a nitrogen 
strength of 0-000253 gm. per | c.c., the arterial fluid having a 
nitrogen strength of 0-000093 gm. and the 46 fluid in the renal 
afferent veins of 0-000193 gm. The nitrogen strength of the 
urine is thus (other things equal) purely a function of the fluid 

ing experiments at length x an 
yasiftl, sities. nmgth as examples of the methods adopted 
2 Ascertained by Gulick’s method (Jour. Biol. Chemistry, Vol. 18, 
1914, p, 541). Details of the method are also given in Plimmer’s ‘‘Practi- 
cal Organic and Bio Chemistry”, 1915 p. 557. The late Dr. E. G. Hill 
of Allaha : brought this method to my notice and assisted me in 
practical details. 
' In Appendix B I have supplied some details of these and peigetek 
