388 



Dr. C. A. MacMunn. 



II. A few Observations on Vertebrate Bile Pigments. 



In spite of the labours of physiological chemists some erroneous ideas 

 still prevail as to the colouring-matters of the bile and their spectra. 

 For instance, one sometimes sees bilirubin described as a green 

 pigment ! And in a recently published medical book the author makes 

 the strange statement that human bile owes its colour to biliverdin ! 

 Again, the statement is frequently met with that the bile colouring- 

 matters have no absorption spectra. So far is this from being the 

 case, that the spectroscope is capable of detecting the smallest 

 quantity of the biliary pigments in pathological liquids ; and I have 

 repeatedly been able to detect bilirubin and biliverdin in pus, urine, 

 and other liquids, by its help. 



In former papers* I endeavoured to show how the urinary colour- 

 ing-matters can be prepared artificially from those of the bile and 

 from hsematin; and I demonstrated the presence of a colouring- 

 matter indistinguishable from urobilin in mammalian bile. But, like 

 others, I failed to prepare either bilirubin or biliverdin from haemo- 

 globin or its decomposition products, although the presence of heemo- 

 chromogen could be detected in human and sheep bile. I have since 

 been helped in the matter by an experiment which took place under 

 pathological conditions, and which proves beyond doubt that the 

 transformation may yet be accomplished out of the body. 



I have also to call attention to the fact that in sheep and ox bile the 

 principal colouring-matter is not biliverdin ; for although I have 

 already shown that the body giving the peculiar series of bands is 

 probably, in fact undoubtedly, a partly heematin derivative, I had not 

 studied fully its spectrum nor the best method of procuring it for spec- 

 troscopic study. I have also made a few observations on stercobilin 

 and on urobilin, prepared by sodium amalgam from bilirubin, which 

 show that the conclusion is rather premature that the pigment known 

 as febrile urobilin is identical with either, as I had already inferred. 



Spectra of Bilirubin, Biliverdin, Bilifuscin, Bilihumin, and Bili- 

 prasin. — Bilirubin possesses a peculiar absorptive power for the violet 

 end of the spectrum, and in concentrated solution it absorbs all this 

 end up to D. Dr. Quinlanf proposes that this property should be 

 made use of for the detection of bilirubin in urine. The very abrupt 

 character of the edge of the shading is quite peculiar. It re- 

 sembles in this respect solutions of tetronerythrin and concentrated 

 solutions of lutein, especially of egg-yolk. The red coloration pro- 



* " Proc. Roy. Soc," 1880, vol. 31, pp. 26, 206. 



f " The Application of Spectrum Analysis to the Estimation of Bile in the Renal 

 Secretion of Patients suffering from Jaundice," " Proc. Roy. Irish Acad.," 2nd ser., 

 vol.111 (Science). See also "Die Quantitative Spectralanalyse in ihrer Anwendung 

 auf Physiologie, Physik, Chemie und Technologic" By Carl Vierordt. 1876. 



