

GASTRIC DIGESTION. I 2/ 



(c) Few drops of glycerol extract of pepsinogen -j- 5 c.c. of 0.5 

 per cent sodium carbonate. 



(d) Two or three c.c. of pepsin solution + 2-3 c.c. of i per cent 

 sodium carbonate. 



(<?) Few drops of glycerol extract of pepsinogen -f- 5 c.c. of i 

 per cent sodium carbonate. 



Add a small piece of fibrin to the contents of each tube, keep 

 the five tubes at 40 C. for one-half hour and observe any changes 

 which may have occurred. To (a) add an equal volume of 0.4 

 per cent hydrochloric acid, neutralize (c), (d) and (e) with hy- 

 drochloric acid and add an equal volume of 0.4 per cent hydro- 

 chloric acid. Place these tubes at 40 C. again and note any fur- 

 ther changes which may occur. What contrast do we find in the 

 results from the three last tubes? Why is this so? 



5. Comparative Digestive Power of Pepsin with Different 

 Acids. Prepare a series of tubes each containing one of the follow- 

 ing acids : 0.5 per cent acetic, lactic, oxalic, salicylic, tannic and buty- 

 ric, and 0.2 per cent hydrochloric, sulphuric, nitric, arsenious, and 

 combined hydrochloric. To each acid add a few drops of the gly- 

 cerol extract of pig's stomach and a small piece of fibrin. Shake 

 well, place at 40 C. and note the progress of digestion. In which 

 tubes does the most rapid digestion occur? 



6. Influence of Metallic Salts, etc. Prepare a series of tubes 

 and into each tube introduce 4 c.c. of pepsin-hydrochloric acid so- 

 lution and J^ c.c. of one of the chemicals listed in Experiment 18 

 under Salivary Digestion, page 59. Introduce a small piece of 

 fibrin into each of the tubes and keep them at 40 C. for one-half 

 hour. Note the variations in the progress of digestion. Where 

 has the least rapid digestion occurred? 



7. Sahli's Desmoid Reaction. This is a method for testing gas- 

 tric function without using the stomach tube. The underlying 

 principle of the test is the fact that raw catgut may be digested 

 in gastric juice but is entirely indigestible in pancreatic juice. The 

 test is made as follows : A methylene blue pill is introduced into 

 a small rubber bag and the mouth of the bag subsequently tied with 

 catgut. 1 The small bag is then ingested immediately after the 



1 About 0.05 gram of methylene blue is mixed with sufficient ext. glycyrrhiza 

 to form a pill about 3-4 mm. in diameter. The pill is then placed in the center 

 of a square piece of thin rubber dam and a little bag-like receptacle constructed 

 by a twisting movement. The neck of the bag is then closed by wrapping three 

 turns of catgut about it. The most satisfactory catgut to use is number oo raw 

 catgut which has previously been soaked in water until soft. When ready for 

 use the bag should sink instantly when placed in water and be water-tight. 



