LESSON VIII 



THE DIGESTIVE JUICES (continued] 



Pancreatic Digestion 



1. A 1-per-cent. solution of sodium carbonate, to which a little glycerin 

 extract of pancreas l has been added, forms a good artificial pancreatic fluid. 



2. Half fill three test-tubes with this solution. 



A. To this add half its bulk of diluted egg-white (1 in 10). 



B. To this add a piece of fibrin. 



C. Boil this ; cool ; then add fibrin. 



3. Put all into the water-bath at 40 C. After half an hour, test A and B 

 for alkali -albumin by neutralisation, for proteoses by nitric acid, and for 

 proteoses and peptone by the biuret reaction. 



4. Note in B that the fibrin does not swell up and dissolve, as in gastric 

 digestion, but that it is eaten away from the edges to the interior. 



5. In C no digestion occurs, as the ferments have been destroyed by 

 boiling. 



6. Take a solution of starch, equal quantities in three test-tubes. 



D. To this add a few drops of glycerin extract of pancreas (without 



the sodium carbonate). 



E. To this add a few drops of bile. 



F. To this add both bile and pancreatic extract. 



7. Put these into the water bath, and test small portions of each every 

 half-minute by the iodine reaction. It disappears first in F ; then in D ; 

 while E undergoes no change. Test D and F for maltose by Fehling's 

 solution. 



8. Shake up a few drops of olive oil with artificial pancreatic juice 

 (extract of pancreas and sodium carbonate). A milky fluid (emulsion) is 

 formed, from which the oil does not readily separate on standing. 



9. The foregoing experiments illustrate the action that pancreatic juice 

 has on all three classes of organic food. 



i. On Proteins. Fibrin, albumin, &c. are converted into proteoses and 

 peptone by the ferment trypsin in an alkaline medium. 



ii. On Carbohydrates. Starch is converted into sugar (maltose) by the 

 ferment amylopsin, especially in presence of bile. 



iii. On Fats. These are emulsified. In the body they are also split into 

 fatty acid and glycerin by the ferment steapsin ; but this cannot be shown 

 with the artificial juice, as steapsin is not soluble in glycerin. 



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 



1 Benger's liquor pancreaticus diluted with two or three times its volume of 

 1-per-cent. sodium carbonate may be used instead. 



