69 



LESSON vm 



BILE 



1. Ox bile is given round. Observe its colour, taste, smell, and reaction 

 to litmus paper. 



2. Acidulate a little bile with 20-per-cent. acetic acid. A stringy precipitate 

 r^f a mucinoid substance is obtained. Filter this off and boil the filtrate ; 



J proteid coagulable by heat is present. 



3. Add a few drops of bile to (a) acid-albumin prepared as described in 

 Lesson III., and (6) solution of proteoses to which half its volume of 

 0"2-per-cent. hydrochloric acid has been added. A precipitate occurs in each 

 ease. BUe salts precipitate the unpeptonised proteid which leaves the stomach. 



4. Pettenliofer's Test for Bile Salts. — To a thin film of bile in a capsule 

 add a drop of solution of cane sugar and a drop of concentrated sulphuric 

 acid. A purple colour is produced. This occurs more quickly on the 

 application of heat. The test may also be performed as follows : — Shake up 

 some bile and cane sugar solution in a test-tube until a froth is formed. 

 Pour concentrated sulphuric acid gently down the side of the tube ; it produces 

 a pintle colour in the froth. 



5. Chneliii's Test for Bile Pigments. — On to a little faming nitric acid 

 (i.e. nitric acid containing nitrous acid in solution) in a test-tube pour gently 

 a little bile. Notice the succession of colours — green, blue, red, and yeUow 

 — at the junction of the two liquids. This test may also be performed in a 

 capsule. Place a drop of fuming nitric acid in the middle of a thin film of 

 bile ; it becomes surrounded by rings of the above-mentioned colours. 



6. Examine crystals of cholesterin microscopically. 



7. To a few cholesterin crystals add a drop of iodine solution and a drop 

 of concentrated sulphiudc acid. A play of colours (red, green, blue) is 

 produced. Other tests for cholesterin are described on p. 74. 



Bile is the secretion of the liver which is poured into the duo- 

 denum ; it has been collected in living animals by means of a biliary 

 fistula ; the same operation has occasionally been performed in hvunan 

 beings. After death the gaU bladder pelds a good supply of bile 

 which is more concentrated than that obtained from a fistula. 



Bile is being continuously poured into the intestine, but there is 

 an increased discharge immediately on the arrival of food in the duo- 

 denum ; there is a second increase in secretion a fev? hours later. 



Though the chief blood supply of the hver is by a vein (the portal 

 vein), the amount of blood in the hver varies with its needs, being 

 increased during the periods of digestion. This is due to the fact 



