172 LABORATORY GUIDE JN PHYSIOLOGY. 



ture occasionally for several days. The glycerin 



extracts the pepsin ferment. 

 (rtT) Strain the glycerin extract through fine linen; 



preserve in a glass stoppered bottle for future use. 



It will keep indefinitely. 

 (*) For use add to 1 volume of the extract 30 to 50 



volumes of 0.2% HC1. Label: Artif. gast. juice (2). 

 j. Experiments and Observations. 



(1) To a bit of starch paste of the consistency of jelly 

 add artificial gastric juice (1); place in the incubator; 

 in ten minutes or one day note results. Results? 



(2) To a few drops of olive oil or to a bit of pure 

 tallow add several cubic centimeters of gastric juice 

 and keep at incubator temperature for a day. What 

 effect has gastric digestion upon fat or oil ? 



(3) To a bit of pig fat add gastric juice and keep at 

 incubator temperature for several hours. What 

 effect has gastric digestion on adipose tissue ? 



(4) To a bit of fibrin in a test tube add gastric juice. 

 The warmth of the hand will be sufficient. If the 

 preparation of artificial gastric juice has been suc- 

 cessful, the fibrin will dissolve in one or two min- 

 utes. One may be certain that digestion is pro- 

 gressing rapidly, though complete solution of the 

 fibrin does not necessarily indicate complete diges- 

 tion of it; for complete digestion of a proteid im- 

 plies that the food stuff in question is both dissolved 

 and diffusible. The fibrin is dissolved, it may or 

 may not be diffusible. But this will be determined 

 later. 



(5) To determine the active factors of gastric digestion, 

 (a) To a few shreds of fibrin in a test tube add a 



few cubic centimeters of 0.2% HC1. Carefully note 

 results. Will dilute HC1 dissolve fibrin? Is it 



