406 PATHOLOGICAL PIGMENTATION 



chiefly in gall-stones (q. v.). A pigment similar to urobilin may be 

 present in normal bile. The total amount of pigments present in bile 

 is probably not far from one gram per liter ; rather under than above 

 this amount. 



Etiology of Icterus. Although hematoidin, which is 

 isomeric if not indentical with bilirubin, may be formed outside 

 of the liver when red corpuscles are broken up in hemorrhagic 

 extravasations, and possibly also when they are broken up 

 within the vessels by hemolytic agents, yet it is generally con- 

 sidered that a true general icterus does not occur without the liver 

 being implicated. This view rests on evidence of various sorts. 

 First, the classical experiments of Minkowski and Naunyn, 1 

 which demonstrated that in geese the production of hemolysis 

 by means of arseniuretted hydrogen leads to icterus, but if the 

 livers of the geese have been previously removed, no icterus fol- 

 lows the poisoning. Second, the repeated demonstration that 

 in icterus produced by septic conditions, poisoning, etc., which 

 was formerly looked upon as a " hematogenous " icterus, the 

 urine contains bile salts as well as pigment, indicating an absorp- 

 tion of bile from the liver. Third, the finding of histological 

 evidence that in so-called hematogenous icterus there occur 

 occlusions or lesions of some sort in the bile capillaries, which 

 can account for the reabsorption of the bile into the general cir- 

 culation. 2 Joannovics 3 gives, as a result of a comparative 

 study of icterus from bile obstruction and icterus from hemol- 

 ysis, the following chief differences : Icterus due to hemolysis 

 appears sooner than icterus from bile-duct occlusion, and reaches 

 a much higher degree ; the obstruction in hemolytic icterus is 

 intra-acinous ; in stasis it is chiefly inter-acinous ; in hemolytic 

 icterus there is a large splenic tumor due to accumulation of 

 degenerated red cells in the spleen, where they become disin- 

 tegrated preliminary to the formation of bile-pigment. If the 

 spleen is removed, hemolytic agents do not cause icterus, because 

 the corpuscles are not then prepared for pigment formation. 



Therefore, it is believed that the pigments that produce the 

 general discoloration of icterus are, at least for the most part, 

 manufactured by the liver, whatever the cause of the reabsorp- 

 tion of the bile from the liver into the blood may be. That 



1 Arch. f. exp. Pathol. u. Pharm., 1886 (21), 1. 



2 See Eppinger, Ziegler's Beitr., 1903 (33), 123; Gerhardt, Munch, med. 

 Woch., 1905 (52), 889. Lang (Zeit. exp. Path. u. Ther., July, 1906, Bd. 3) 

 has demonstrated the presence of fibrinogen in the bile in phosphorus- poison- 

 ing, which perhaps accounts for the " bile thrombi " observed by Eppinger in 

 toxic icterus. 



3 Zeit. f. Heilk., Path. Abt., 1904 (25), 25. 



