154 Journal of the Asiatic Society of Bengal. [N.S., XVIII, 
Finally, apart from it being an attempt to explain the 
encapsulation of the glomerulus, the neo-I.udwig theory is 
supposed to be superior to all rival theories in its simplicity. 
This simplicity is supposed to lie in the statement that if we 
assume glomerular filtration of the non-colloid portion of the 
blood and tubular absorption of Locke’s fluid, a key is thereby 
provided for the interpretation of all the data of kidney activi- 
ty. But, quite apart from the question as to whether this is 
blood only receives rather than to the numerous other kinds 
of glands in which, as in the kidney, the blood chiefly relinqgaish- 
es. I contend moreover that a theory which assumes that the 
kidney is an organ which devotes about 99% of its substance 
to returning to the blood £¢ ths of what the 1% has abstract- 
ed from it is anything but simple. Cushny however argues 
(p. 53) that although for the daily excretion of 35 grams of 
urea the neo-Ludwig theory requires 70 litres of glomerular 
filtrate to be separated from the blood colloids and 68 of these 
to be re-absorbed through the tubule epithelium, yet the 
Bowman-Heidenham (Tubule cum Rete) theory likewise re- 
quires 70 litres of plasma to exude into the lymph spaces round 
vessels, and therefore ‘‘ the two rival theories... ... both require 
about the same amount of fluid to come into contact with the 
e pithelium”’ and therefore ‘‘ the difficulty is almost equally great 
in accepting either theory.”’ ; 
But this is not a valid comparison between the require 
wall of the tubule, whereas, on the Tubule cum Rete theory, 
the 68 litres would only be supposed to be separated in the 
a ey ee ———— 
tubules, either of these structures may have supplied the water: the 
sr me for glomerular secretion or filtration is therefore worthless. 
the bloo which traverses its blood vessels. It is quite evident that, des- 
P 7 Cushny’s comparisons between the two, there can be no real likeness 
whatever between the functions of the villus epithelium and that of the 
kidney tubule. 

