544 AN AMERICAN TEXT- HOOK OF 1'HYSloLOGY. 



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

 in various parts of the body. Cholic, fellic, 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 beguu to decrease. 1 The experiments 

 of Feder 2 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 fellic acids are produced from the 

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

 6ho\\^i that cholic acid on oxidation yields fatty acids. A synthesis may there- 

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

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

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

 it from tlu 1 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. 



The biliary salts in part may be absorbed by the intestine, and a part of 

 these absorbed salts may be again excreted through the bile, forming a circu- 

 lation of the bile salts. In the intestine either the acid of the gastric juice 

 or bacteria may split up the biliary salt through hydrolysis: 



C 26 H, 3 M\+ H 2 - C 2 H 6 N0 2 + C.^H^O,. 



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, fellic acid, etc., may often be found in the feces in small 

 amount-. .Meconium, that is. the fecal matter of the fetus, contains quantities 

 of the biliary salts, but unaltered, since putrefaction is absent in the fetus. 

 Kiihne has described dyslysin as a putrefactive product of cholic acid, but its 

 existence is denied by Hoppe-Seyler and Yoit. In icterus (jaundice), a con- 

 dition in which the biliary salts return to the blood from the liver, they are 

 burned in the body, sometimes so completely that none appear in the urine. 

 They have the power of dissolving haemoglobin from the blood-corpuscles, and 

 in consequence the urine may be highly colored, perhaps from bilirubin. 5 



The biliary salts have the power of dissolving the more insoluble fatty 

 acids and soaps produced from the action of steapsin on fats. 1 ' 



Pettenkofer, experimenting once on the conversion of sugar into fat. warmed together 

 cane-sugar, bile, and concentrated sulphuric acid. He obtained no fat, but a strong violet 

 coloration. This is " Pettenkofer's test" for biliary acids (cholic acid, fellic acid, etc.). 

 This coloration is likewise given by proteid, oleic acid, and other bodies. The test of'Neu- 



1 Yoit : Zeitschrift fur Biologie, 1894, Bd. 30, S. 545. 2 Ibid., 1881, Bd. 15, S. 531. 



5 Yoit, Op. ril., S. 556. 4 Zeitschrift fur Biologie, 1876, Bd. 12, S. 60. 



5 Hoppe-Seyler: Physiohgische Chemie, 1877, S. 476. 



6 Moore and Rockwood : Journal of Physiology, 1897, vol. xxi. p. 58. 



