162 A Manual of Veterinary Physiology. 



The actual production of bile pigments takes place in the 

 liver, but the means by which the latter organ is furnished 

 with free hemoglobin for the purpose is still obscure. 



The Bile Salts are two in number, glycocholate and tauro- 

 cholate of soda. They are formed by the union of cholalic 

 acid with glycin or taurin, and exist in combination with 

 soda. These salts are found to exist in varying proportions 

 in different animals — thus, while glycocholate of soda is 

 largely found in herbivora, taurocholate is the principal 

 constituent of dog's bile, and in pig's bile hyoglycocholic 

 and hyotaurocholic acids are found. Both salts are soluble 

 in water, have a decided alkaline reaction, rotate the plane 

 of polarized light to the right, and may be obtained in the 

 crystalline form of acicular needles highly deliquescent. 



Glycocholic acid is the chief bile acid in herbivora ; it is 

 produced by the union of glycin with cholalic acid. Glyco- 

 cholic acid is diminished b}~ an animal diet, and increased 

 by a vegetable one. 



Taurocholic acid is produced from taurin and cholalic 

 acid, and exists principally in carnivora, though small 

 quantities may be found in the ox. This acid differs from 

 the first characteristically by containing sulphur, by which 

 it shows its proteid origin. 



In the intestine the constituents of the bile are absorbed : 

 both acids are decomposed or split up by ferments into 

 cholalic acid and glycin or taurin, the two latter being re- 

 absorbed. 



Glycin or glycocoll originates from proteids, and if ad- 

 ministered it reappears externally as urea. It cannot be 

 traced in the free state in the body, but occurs with 

 benzoic acid, from which combination is formed hippuric 

 acid ( Bunge). 



In rettenkofer's test for bile acids the reaction obtained 

 is due to cholalic acid. The test is performed as follows : 

 A drop of the fluid is placed on a white earthenware sur- 

 face, and to it is added a drop of a strong solution of cane- 

 sugar, and a similar quantity of strong sulphuric acid; a 

 beautiful purple-red colour forms, which ina\ be assisted 



