BILE ACIDS AND PIGMENTS. 563 



Kunkel, 1 from similar experiments on dogs, concluded that a definite 

 part of the sulphur taken in the diet is excreted in the bile, but the 

 increase in biliary sulphur occurs two or three days after the ingestion, 

 and not upon the same day, as is the case with the sulphur of the urine. 

 Of the sulphur of the food, from 8 to 30 per cent, is excreted in taurine. 



In man on an ordinary diet, about 33 grins, of urea with 15 grms. of 

 nitrogen are daily formed, while only about 10 grms. of bile acids with 

 about 0'3 grms. of nitrogen are excreted. The increased ingestion of 

 proteids leads to a proportionate increased excretion of urea, and any 

 increase in the bile acids is necessarily so small that it may readily 

 be overlooked. Similarly, any increased decomposition of the proteids 

 of the tissues leads to a proportionately increased excretion of the 

 nitrogen in the form of urea, and any increase in the bile acids which 

 may occur must be very trifling. 



Whether the bile acids which are absorbed from the intestine can 

 be again excreted by the liver cells, has been investigated by injecting 

 into the blood of animals a bile salt differing from that which is normally 

 present. In dogs the taurocholate of soda is the normal salt of the 

 bile. After injecting glycocholate of soda, Prevost and Binet, 2 and 

 Weiss a found it in the dog's bile. Socoloff, 4 on the other hand, failed 

 to detect it after it had been injected. Huppert 5 observed that the 

 injection of glycocholic acid increases the amount of bile acids in the 

 bile. The experiments of Eosenberg 6 show that the administration of 

 bile salts causes an increased secretion of bile with a marked increase 

 in the solids. They appear to be the only substances which produce 

 this result, and since the bile salts are the most abundant solids of bile, 

 it seems fairly certain that they are absorbed, and re-excreted from the 

 blood by the liver. 



Bile pigments. The pigments must be produced in the liver cells, 

 since the secretion from the bile passages is entirely destitute of colour- 

 ing matter. 7 They are formed from the haematin moiety of the haemo- 

 globin molecule. The injection of free haemoglobin into the blood, 8 or 

 the setting free of haemoglobin by solution of the red corpuscles, 9 rapidly 

 leads to a great increase of the bilirubin of the bile. Minkowski and 

 Naunyn, by experiments upon birds, 10 have confirmed these observations. 

 They further found that if the liver is excluded from the circulation 

 the formation of bilirubin does not take place. They thus showed that 

 bilirubin is actually produced in the liver cells. The iron-containing 

 part of the haematin molecule appears to be split off and retained in 

 these cells, giving rise to the accumulation of iron in the liver, which 

 follows the disintegration of red corpuscles. 11 



Not only do the liver cells manufacture bilirubin, but when this or 

 any other bile pigment is present in the blood they take it up and eliminate 



1 Arch.f. d. ges. PhysioL, Bonn, Bd. xiv. S. 344. 



2 Compt. rend. Acad. d. sc., Paris, 1888, tome cvi. p. 1690. 



3 Bull. Soc. imp. d. nat. de Moscou, 1884. 



4 Arch.f. d. ges. PhysioL, Bonn, 1875, Bd. xi. S. 166. 



5 Arch. d. Heilk., Leipzig, 1869, Bd. v. 



6 Arch.f. d. ges. PhysioL, Bonn, 1890, Bd. xlvi. S. 334. 



7 Birch and Spong, Journ. PhysioL, Cambridge and London, vol. viii. p. 378 ; Mayo 

 Robson, Proc. Roy. Soc. London, 1890, vol. xlvii. p. 499. 



8 Stiidelmann, Arch.f. exper. Path. u. PharmakoL, Leipzig, 1890, Bd. xvii. S. 93. 



9 Afanassiew, Ztschr. f. klin. Mcd., Berlin, Bd. vi. Heft 4. 



10 Arch.f. exper. Path. u. PharmakoL, Leipzig, 1886, Bd. xxi. S. 1, 



11 Hunter, Lancet, London, 1892, p. 1262. 



