366 DIGESTION. 



ing the chemistry of this fluid ; deferring a full account of its 

 composition until we come to treat of it as an excretion. 



The bile varies in color and consistence in different ani- 

 mals. It usually has a greenish, yellowish, or brownish hue. 

 In the human subject, it has a dark golden-brown color, 

 and is somewhat viscid in consistence, chiefly from ad- 

 mixture with the mucus of the gall-bladder. The specific 

 gravity of human bile has been found to be about 1,018.' Its 

 reaction is faintly alkaline. 



Physiological chemists have long since recognized in the 

 bi]e peculiar principles, which are found in no other part of 

 the organism ; but the exact nature of these constituents was 

 first described by Strecker, in 1848. The principle described 

 by Eerzelius under the name of biliary matter, subsequently 

 separated by Thenard into two principles, called by him bil- 

 iary resin and picromel, and afterward treated of by Tiede- 

 mann and Gmelin, who obtained two substances, which they 

 called taurine and cholic acid, was analyzed by Strecker, who 

 obtained from the bile of the ox two acids, cholic and cho- 

 leic acid, which he found existed in this fluid in combina- 

 tion with soda. 2 The results of these researches by Strecker 

 into the chemistry of the bile, the most extended and accu- 

 rate which had ever been made, are now generally accepted 

 by physiologists. The cholic acid of Strecker, which may 

 be decomposed into a new acid and a principle called glycine, 

 and the choleic acid from which may be formed a new acid 

 and taurine, are called by Lehmann, respectively, glycocholic 

 and taurocholic acid. 3 In the bile of the ox, these are found 

 combined with soda, and the peculiar proximate principles 

 of this fluid are now recognized as the glycocholate of soda, a 



1 DALTON, Human Physiology, Philadelphia, 1864, p. 175. 



2 STRECKER, Untersuchung der Ochsgalle. Annalen der Chimie rind PJiarma- 

 cie, Heidelberg, 1848, Bd. Ixv. S. 1 et scq. ; and Bd. Ixvii., S. 1 el seq. ; Beobach- 

 lungen uber die Galle verschiedener Thiere, Idem, 1849, Bd. Ixx., S. 149 et seq, 

 An analysis of the above is given in the Journal de Pharmacie ft de Chimie, 

 Paris, 1848, tome xiii., p. 215 ; 1849, tome xv., p. 153 ; and tome xvi., p. 450. 



3 LEHMANN, Physiological Chemistry, Philadelphia, 1855, vol. ii.,p. 201 et seq. 



