THE DIGESTIVE JUICES 



91 



Bile Mucin. There has been considerable diversity of opinion as 

 to whether bile mucin is really mucin. The most recent work in 

 Hammarsten's laboratory shows that differences occur in different 

 animals. Thus in the ox there is very little true mucin, but a great 

 amount of nucleo-protein ; in human bile, on the other hand, there is 

 very little if any nucleo-protein ; the mucinoid material present there 

 is really mucin. (On the general characters of MUCIN and NUCLEO- 

 PROTEINS see pp. 45 to 47.) 



The Bile Salts. The bile contains the sodium salts of complex 

 amino-acids called the bile acids. The acids most frequently found 

 are glycocholic and taurocholic acids. The former is more abundant 

 in the bile of man and herbivora ; .the latter in carnivora like the 

 dog. The most important difference between the two acids is that 

 taurocholic acid contains sulphur, and glycocholic acid does not. 



Glycocholic acid (C 2G H 43 NO G ) is by the action of dilute acids and 

 alkalis, and also in the intestine, hydrolysed and split into glycine or 

 amino-acetic acid and cholalic acid. 



C 2G H 43 NO G + H 2 0=CH 2 .NH 2 .COOH + C 24 H 40 O 5 



[glycocholic acid] [glycine] [cholalic acid] 



The glycocholate of soda has the formula C 2G H 42 NaNO G . 

 Taurocholic acid (C 2G H 45 N0 7 S) similarly splits into taurine or 

 ammo-ethyl-sulphonic acid and cholalic acid, 



C 26 H 45 N0 7 S + H 2 0=C 2 H 4 .NH 2 .HS0 3 + C 24 H 40 O 5 



[taurocholic acid] [taurine] [cholalic acid] 



The taurocholate of soda has the formula C 2 6H 44 NaNO 7 S. 

 Glycocholic and taurocholic acids have lately been prepared 

 synthetically from cholalic acid and glycine and taurine respectively. 

 The colour reaction called Pettenkofer's reaction, described in the 



