DIGESTION. 79 



mometer and keep the temperature at 100 F. or 42 C. 

 The body temperature is about J$&^ C. j>7 6 - 



II. THE ACTION OF GASTRIC JUICE ON PROTEIDS. 



Materials. Egg-albumin. Artificial gastric juice. Water. 

 Apparatus. Evaporating dish. Glass stirring rod. Test-tubes 

 and rack. Warm water-bath and thermometer. 



Caution. Label all of your test-tubes. 

 Experiment : 



1. (Preliminary) Heat some water in an evaporating 



dish. Into this drop a little well-shaken egg- 

 albumin and stir constantly. 



2. Add a small piece of the coagulated albumin, 



not minced, to 10 c.c. of gastric juice. Keep 

 it cool and still. 



3. Add a small piece of the egg-albumin, minced, to 



10 c.c. of gastric juice. Place it in the water- 

 bath but keep it still. 



4. Add the same amount of minced egg-albumin 



to 10 c.c. of gastric juice. Keep at 42 C., but 



" shake often to imitate the action of the stomach. 



Compare the three results at the end of two 



hours. What three conditions aid jdigestion 

 - 



III. ARE BOTH ACID AND PEPSIN NECESSARY TO 



DIGESTION ? 



Materials. Coagulated egg-albumin. Water. Dilute hydrochloric / 

 acid. Pepsin. 



Apparatus. Test-tubes. Warm water-bath. 



Place a small piece of coagulated egg-albumin in each 

 of four test-tubes. 



