THE CHEMISTRY OF THE ANIMAL BODY. 987 



It is likewise a usual constituent of the human bile in combination with 

 cholic acid, the salt present being known as sodium taurocholate. Taurin 

 is of proteid origin as is shown by its nitrogen and sulphur content. Little 

 is known regarding its fate in the body, except as it indicated through the 

 behavior of its sulphur atom (see p. 951). 



The. Biliary Salts. Taurin and glycocoll are found in the bile of cattle in 

 combination with cholic acid (C^H^Oj). In human bile, according to Lassar- 

 Cohn, 1 there is more fellie acid (C^HggOJ present than cholic, and there is 

 likewise present some choleic add, (C^H^Og). These acids are of similar chemi- 

 cal structure, though what the structure is, is unknown. Still other acids 

 occur in the bile of pigs, geese, etc. Taurin and glycocoll form compounds 

 with these acids, the sodium salts of which usually make up the major part of 

 the solids of the bile. It has been shown that glycocoll and taurin are found 

 in various parts of the body. Cholic, fellie, etc. acids are only found as products 

 of hepatic activity. In a dog with a biliary fistula the solids of the bile increase 

 on feeding much meat, but the hourly record of the solids compared with 

 the nitrogen in the urine shows that the great production of biliary salts con- 

 tinues after the nitrogen in the urine has begun to decrease. 2 The experiments 

 of Feder 3 have shown that the greater part of the nitrogen in proteid eaten by 

 a dog leaves the body within the first fourteen hours, whereas the excretion of 

 the non-nitrogenous moiety is more evenly distributed over twenty-four hours. 

 It may be fairly concluded that cholic and fellie acids are produced from the 

 non-nitrogenous portion, or from sugar or fat. 4 Furthermore Tappeiner 5 has 

 shown that cholic acid on oxidation yields fatty acids. A synthesis may there- 

 fore be effected in the liver between the non-nitrogenous cholic acid formed in 

 the liver from fat or materials convertible into fat, and glycocoll and tauriu 

 formed from proteids, whether the latter be produced in the liver or brought to 

 it from the tissues by the blood. That the liver is the place for the synthesis 

 is shown by the fact that the biliary salts do not collect in the body after extir- 

 pation of the liver. 



In the intestine either the acid of the gastric juice or bacteria may split up 

 the biliary salt through hydrolysis : 



C^NO, + H 2 = C 2 H 5 N0 2 + C 24 H<A. 



Glycocholic acid. Glycocoll. Cholic acid. 



Taurin and glycocoll may be absorbed, while cholic acid is precipitated if in 

 an acid medium, but may be dissolved and absorbed in an alkaline intestine. 

 Hence cholic acid, fellie acid, etc., may often be found in the feces. Meco- 

 nium, that is, the fecal matter of the fetus, contains quantities of the biliary 

 salts, but unaltered, since putrefaction is absent in, the fetus. Kuhne has de- 

 scribed dyslysin as a putrefactive product of cholic acid, but its existence is 

 denied by Hoppe-Seyler and Voit. In icterus (jaundice), a condition in 



1 Zeitschriftfilrphysiologische Chemie, 1894, Bd. 19, p. 570. 



2 Voit : Zeitschriftfiir Biologie, 1894, Bd. 30, p. 545. 3 Ibid., 1881, Bd. 17, p. 531. 

 4 Voit, Op. cit., p. 556. 5 Zeitschriftfiir Biologic, 1876, Bd. 12, p. 60. 



