THE FUNCTIONS OF THE DIGESTIVE ORGANS. 515 



this last acid are different from the first cholic acid, and it has a higher 

 melting-point. A hijoglycocholic acid 1 has been isolated from the bile of 

 pigs. 



Taurocholic acid 2 is found in the bile of man, carnivora, oxen, and a few 

 other herbivora, and yields, on being boiled with acids or alkalies, taurine 

 and cholic acid. It has the empirical formula C^HisNSOy. In the bile 

 of the goose the so-called cheno-taurocholic acid is found. 3 



In the bile of the shark, Scymnus borealis, Olof Hammarsten, 4 to 

 whom our thanks are due for most careful investigations concerning 

 the bile of different species of animals, found in place of the usual 

 bile-acids, two ethereal-sulphuric acids which he called scy mud-sulphuric 

 acids. They yield on hydrolysis, besides sulphuric acid, a non-nitrogen- 

 ous acid, scymnol, which gives the characteristic color reactions of cholic 

 acid. 



As we have said, only one constituent of the bile-acids is understood 

 in each case as regards its composition, and this is either glycocoll or 

 taurine. These two substances originate, as we have already discussed 

 in detail, from the proteins, and, in fact, glycocoll is recognized as one of 

 the direct cleavage-products of albumin, while it is perfectly evident that 

 taurine is formed from cystine. 



The constitution of cholic acid is not yet clearly established. Mylius 5 

 has succeeded in obtaining from it a monobasic hydroxy-acid with one 

 secondary and two primary alcoholic groups. By oxidation of cholic 

 acid, the so-called dehydrocholic acid C24H 34 05 is formed; while by more 

 energetic oxidation bilianic acid C 2 4H 34 08 is obtained, perhaps more 

 correctly a mixture of bilianic and isobilianic acids. By the oxidation of 

 bilianic acid, the so-called cilianic acid, C2oH 2 8O 8 , is formed. On reduc- 

 tion, cholic acid yields desoxycholic acid, C 2 4H 4 oO4. According to our 

 present knowledge, we can give to cholic acid the following formula: 



fCH(OH) 

 C 20 H 31 {(CH 2 OH) 2 



ICOOH 



Severin Jolin: Z. physiol. Chem. 12, 512 (1888); 13, 205 (1889). 



Concerning the preparation of pure taurocholic acid, see 0. Hammarsten, Z. physiol. 

 Ch in. 43, 127 (1904), and Stefan Tengstrom: ibid. 41, 210 (1904). 



Heintz and Wislicenus: Poggendorffs Annal. 108, 547 (1859). 



Z. physiol. Chem. 24, 323 (1898). 



Cf. Strecker: Annal. 65, 1 and 130 (1848); 67, 1 (1848); 70, 149 (1849). F. Mylius: 

 Ber. 19, 369 and 2000 (1886); Z. physiol. Chem. 12, 262 (1888). P. T. Cleve: Compt. 

 rend. 91, 1073 (1880). Olof Hammarsten: Ber. 14, 71 (1881). Lassar-Cohn: ibid. 32, 

 683 (1899). Z. physiol. Chem. 17, 607 (1893). Fritz Pregl: Pfluger's Arch. 71, 303 

 (1898); 72, 266 (1898) ; Sitzber. kaiserl. Akad. Wissensch. in Wien, Math, naturw. Klasse, 

 111, Abt. II b. October, 1902, and Z. physiol. Chem. 45, 166 (1905). G. Bulnheim: 

 Z. physiol. Chem. 25, 296 (1898). 



