DIGESTION 



muscle-fibers, which when in action completely close the orifice and prevent 

 the discharge of bile. It may therefore be regarded as a true sphincter 

 muscle, the structure and function of which were first pointed out by Oddi 

 Small racemose glands are embedded in the mucous membrane of the main 



Physical Properties. The bile obtained directly from the liver through 

 a cannula inserted into the hepatic duct is always thin and watery while 

 that obtained from the gall-bladder is more or less viscid from admixture 

 with mucin, the degree of the viscidity depending on the length of time it 

 remains in this reservoir. The specific gravity of human bile varies within 

 normal limits from i.oio to 1.020. The reaction is invariably alkaline in 

 the human subject when first discharged from the liver, but may become 

 neutral in the gall-bladder. The alkalinity depends on the presence of 

 sodium carbonate and sodium phosphate. When fresh, it is inodorous; but 

 it readily undergoes putrefactive changes, and soon becomes offensive ' Its 

 taste is decidedly bitter. When shaken with water, it becomes frothy a 

 condition which lasts for some time and which is due to the presence of mucin. 

 In ox bile the mucin is replaced by a nucleo-protein. 



The color of bile obtained from the hepatic duct is variable, usually a 

 shade between a greenish-yellow and a brownish-red. In different animals 

 the color varies. In the herbivorous animals it is usually green; in the car- 

 nivorous animals it is orange or brown. In man it is green or a golden 

 yellow. The colors are due to the presence of pigments. Microscopic 

 examination fails to show the presence of structural elements. 



Chemic Composition. Human bile obtained from an accidental biliary 

 fistula was shown by Jacobson to contain the following ingredients, viz.: 



COMPOSITION OF HUMAN BILE 



Water 911.** 



Sodium glycocholate p.^4 



Sodium taurocholate a trace 



Cholesterin 0.54 



Free fat O . IO 



Sodium palmitate and stearate i .36 



Lecithin ; o .04 



Organic matter, and pigments bifirubin and biliverdin 2 .26 



Sodium chlorid 5.45 



Potassium chlorid 0.28 



Sodium phosphate i .33 



Calcium phosphate 0.37 



Sodium carbonate 0.93 



In this analysis the solid ingredients constitute 22.6 parts per 1000, of which 

 two-thirds are organic and one-third inorganic. The amount of solid varies 

 according to the animal from which the bile is obtained. 



Sodium Glycocholate and Taurocholate. Of the various ingredients 

 of the bile none are more important than these two salts, usually known as 

 the bile salts. The sodium glycocholate is found most abundantly in the 

 bile of herbivora, the sodium taurocholate in the bile of the carnivora. These 

 salts are compounds of sodium and glycocholic and taurocholic acids. 

 When separated from the sodium, the acids will crystallize in the form of 

 fine acicular needles. Under the influence of hydrolizing agents, such as 

 dilute acids and alkalies, both acids will undergo cleavage into their re- 



