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Trext-FicuRE 1. Comparison of sections a artery and vein geet 
; ted frog kidney 
A (x 330) Camera lucida drawing of a eiabs of a section across a 
—— injected with indigo-carmine via the renal ates Ink-like 
e was being excreted. e was present in various meg in all the 
giomeit. but none in the capsules (in which positi ave never 
observed it; though if it occurred I should attribute it to inflow from 
the tubule lumina, 
could be detected in the ema ss tubule cells. ; as present 
in the large intertubular spaces (venous sinusoids). 
B 0 era Tete drawing of a similar piece « cs a section 
across a kidney similarly injected with indigo-earmine but v the renal 
fferent vein. The urine was practically colorless. Dye bia: entir sd 
b 
an. 
sytem (as assumed ‘in current literature) the dye injections of both kidneys 
in the region of the tubules would have been si milar in appearanve, the 
only difference being one of quantity. 
: (x 5) Diagram (constructed sees serial horizontal sections = the 
kidney injected with carmine via the enal afferent vein) of the renal 
venous meshwork of the frog’s kidney (Robe tigrina). The presence o 
the large interlobular channels connecting — gene affe rent vein ase the 
i at 
