336 Proceedings of Royal Society of Edinburgh. [sess. 
and thereby reduced to a body resembling the artificial hydro- 
bilirubin which, absorbed from the intestine, traverses the liver, 
and so, by the lungs, reaches the arterial stream for the kidney. 
Against this theory may be urged the following considerations : — 
1. In animals with a biliary fistula the urine has urobilin. 
2. In Copeman and Winston’s case * of human biliary fistula, 
where the faeces were “ clay-coloured,” the urine contained uro- 
bilin, on SGme days in excessive quantity. 
3. A body constantly present is made to depend upon a fluctuat- 
ing quantity like “ nascent hydrogen.” 
4. Why, if bilirubin, formed in the liver is at once excreted from 
if in the bile, should hydrobilirubin pass through the liver un- 
changed, or pass through it at all into the blood for the right 
auricle ? 
5. In fevers, whereas the amount of bile is diminished, urobilin 
is increased. 
The fate of the bile-pigments will still further determine the site 
of the source of urobilin. The bile-pigments, acted upon in the 
intestine by some de-oxidising agent either contained in pancreatic 
juice f or acting in its presence, forms stercobilin, the brown faecal 
pigment thus eliminated ; for (1) before the pancreas secretes we 
have meconium (thick foetal bile-pigment unaltered) ; and (2) 
although bile be secreted, if the pancreas is diseased or its duct 
occluded, stercobilin is absent from the faeces ; (3) in vigorous 
catharsis, when bile-pigment is hurried through the intestine, it 
may be yellow (bilirubin) and not brown (stercobilin). 
[Recently it has been suggested, from the spectroscopic affinities 
between stercobilin and pathological urobilin, that the presence of 
the latter in urine may be due to an abnormal absorption of the 
former from the bowel.] 
Unquestionably haemoglobin via haematin (normally) is the 
parent of both the bile-pigment and the urinary pigment, and it is 
most probable both are the offspring of haematin of the same 
generation. 
Thus, though the biliary origin of urobilin must be given up, 
there is much to point to its hepatic origin ; that the liver is the 
* Jour, of Phys., x. p 21. 
t T. J. Walker, Mcd.-Chir. Trans., Lond., vol. lxxii., 1890. 
