144 Journal of the Asiatic Society of Bengal. |N.S., XVIII, 
eliminate water (and the salts) in equal or greater quantities in 
the absence of these structures. If it be argued that the water 
is required to “ flush” the tubules (5 or 6 cms. in length, 13) 
either by setting up a “ pressure head ”’ (11) or by acting as a 
pump, the needlessness of the glomeruli to effect this object is 
evident when we call to mind the facts that the semi-solid non- 
motile semen can travel down 50 cms. of a testis tubule, the 
narrow passage of the rete testis and some 600 cms. of coiled 
epididymis duct without any such aid. and that bile traverses 
channels fully as narrow as and much longer than those of the 
renal tubules in order to reach the gall bladder. 
Finally, there is the possibility of alternative explanations 
of the raison d’étre of the encapsulated glomerulus, and if there 
be any evidence in support of these, then, in view of the objec- 
tions to the current explanations and indeed their final dis- 
proof, there is good reason for accepting any one or more of 
them as working hypotheses. 1 propose to offer three explana- 
tions, cach non-contradictory of and to some extent supplemen - 
tary to the others, for which I think there is much to be said. 
The first explanation is based on the fact that most or all thin- 
illari ymph and since the glomerular capil- 
laries are known to be ‘extremely thin’? and the blood 
suppose that they exude lymph or would if they could, despite 
the absence of a ‘“‘chemical’’ factor. Now if the glomeruli 
merely lay between the tubules, adjacent to but not in contact 
with them, this lymph would freely escape from the glomeruli 
into the intertubular spaces in such quantity as to lead to an 
enormous excessive production of urine and so to defeat the main 
purpose of the glomeruli, which, as we have seen, is to limit the 
output of water and salt while ensuring the due elimination of 
nitrogenous matter. To obviate this escape of lymph, the 
glomeruli become encapsulated, or, in other words. completely 
surrounded by a thin non-permeable ! portion of the tubule wall 
which effectually returns the exuded lymph to the glomerular 
capillaries (or rather prevents its exudation) and so maintains - 
the distended condition of the tubular capillaries which is so es- 
sential to secretion. The inner capsule wall, according to this 
view, is then for the purpose of preventing that very exudation 
a peculiar form of which many physiologists assume to oceur-* 
Sei ioane ane —_—— 


1 If it be urged that it is difficult to imagine one part of the tubule 
wall being impermeable while the remainder is remarkable for its 
permeability, the anal gous case of the physoclist gas bladder may be 
quite impermeable to the cont B, smal the ‘* oval 
freely permits the oxygen to pass through into the blood. 2 
ave not yet had a portunity of meeting with a detailed 
description of the exact way in which the encapsuluted 
supposed to ‘‘ filter.”” To me it is difficult to imagine that filtration only 
