232 



Dr. C. A. MacMunn. Researches into the [Dec. 16, 



not, by any method, see the second band of lutein in violet. More- 

 over, caustic soda and ammonia which intensify the band of lutein, 

 caused this band to disappear ; and when zinc chloride in very small 

 quantity was added after the caustic soda a precipitate fell, but when 

 this was separated from the fluid, I thought I could perceive a faint 

 band from wave-length 516 to 488. If the white of egg is compared 

 with this, as I find that it contains some of the lutein of the yelk, we 

 see two bands distinctly, and that nearer the red is decidedly darkened 

 by both caustic soda and by ammonia ; moreover the first lutein band 

 of the yelk in alcohol read from wave-length 496 to 478. (Lutein 

 itself, even if present, may also be formed in the liver, as I have found 

 it in gall-stones (vide antea), and a pigment giving its spectrum 

 appears to be formed by the long-continued action of caustic soda on 

 the alcoholic extract of the pigments of sheep bile, sp. 4. Thus, the 

 first action was to give sp. 12, Chart IY, but after half-an-hour sp. 13 

 appeared, the other bands having faded away.) 



I therefore conclude that the absorption-band of serum is due to a 

 body which is produced by the oxidation of the bile pigments, and 

 which is on its way to be excreted by the kidneys.* 



Summary and Conclusions. 



(1.) That normal human urine contains a body as such, which is 

 apparently identical with choletelin and with the body produced by 

 the action of peroxide of hydrogen on acid haematin. 



(2.) That normal human urine contains the chromogen of febrile 

 urobilin, which can be prepared artificially by reduction of choletelin, 

 and of the body produced by oxidation from haematoin. 



(3.) That human, ox, sheep, and pig bile contain a kind of urobilin r 

 which differs in some respects from that excreted in urine, and that 

 they also contain haematin. 



(4.) That it is highly probable that all the constituents of bile- 

 colouring matter are produced from haeniatin by reduction. 



(5.) That the haematin present in bile is probably due to the action 

 of the bile acids on haemoglobin. 



(6.) That all the colouring matters of bile, including haematin,. 

 urobilin of biliary origin, bilirubin, &c, are oxidised into choletelin, 

 and that there is evidence to show that blood-serum contains this body, 

 which is on its way to be excreted by the kidneys. 



(7.) That the absorption- bands seen in the bile of various animals 

 are due to the presence of haematin and urobilin of biliary origin. 



(8.) That a pigment excreted in the urine in certain pathological 

 conditions is derived from haematin by reduction, as it can be obtained 

 by reducing acid haematin with zinc and sulphuric acid, and also by 



* Neubauer and Yogel (" Guide to Analysis of Urine," American edition, 1879, 

 p. 64) think this band is due to urobilin. 



