410 PATHOLOGICAL PIGMENTATION 



much urobilin is present in the urine, the tissues do not become 

 pigmented by them. Bile-pigment is probably not absorbed as 

 such from the intestine in sufficient quantity to cause icterus. 

 Such bile -pigment as enters the blood from the liver is excreted 

 through the kidneys chiefly, but also in the sweat. Ordinarily, 

 other secretions (milk, tears, saliva, sputum) are not colored in 

 jaundice, but if the secretions are mixed with inflammatory 

 exudations, they may then be colored (e. g., pneumonic sputum). 

 When the bile-pigment is resorbed from the skin, it is at least 

 in part transformed into urobilin, which appears in the urine in 

 increased amounts during the period of recovery from jaundice. 

 Part of the bile-pigment is probably eliminated by the liver 

 after the cause of obstruction has been removed from the bile- 

 passages. 



Digestive Disturbances in Obstructive Icterus. In case the 

 icterus depends upon the occlusion of the main bile-passages by stones, 

 tumors, etc., the situation is complicated by the effects of the absence 

 of this natural secretion in the intestinal canal. Carbohydrate and pro- 

 teid digestion seem to be but little affected, especially the former, but 

 the proportion of the ingested fat that appears in the feces increases from 

 the normal 7-11 per cent, to 60-80 per cent. The products of bacterial 

 decomposition of the undigested fat may lead to injury of the intestinal 

 wall and disturbance of its function. Failure of absorption of fat also 

 favors intestinal putrefaction by enveloping the proteid substances so 

 that they are not readily digested and absorbed. The relation of bile to 

 intestinal putrefaction is still not exactly determined. Frequently, but 

 by no means always, there is an increased intestinal putrefaction which 

 may result in diarrhea and the appearance of excessive quantities of 

 indican and phenol in the urine. The idea once held that the bile 

 salts acted as intestinal antiseptics has not been established by experi- 

 mental investigations ; however, it is possible that through their func- 

 tion as natural cathartics, by stimulation of peristalsis, they prevent 

 stagnation and putrefaction of proteids. 



