XL. Gastric digestion, continued. 



Experiments and Observations, continued. 



(14) The steps of gastric digestion. 



Boil an egg 5 to 10 min.; cool quickly; separate out the 

 white; press it through a fine sieve; put into a beaker 

 with 100 c. c. artif. gastric juice, and place the beaker 

 in a water bath at 40C. At intervals of 2 minutes for 

 the first 10 minutes; then at intervals of 5 minutes for 

 the next 20 minutes; then at intervals of 10 minutes 

 forthe second half hour and after that at intervals of one 

 hour, subject the liquid to tests for egg albumin; for 

 acid albumin; for albumose; for peptone. In what order 

 and after what length of time do the several products 

 appear? Is the one that is first to appear also first to 

 disappear ? 



(15) The artificial digestion of various proteids. 



(a) To a small mass of jellied gelatin add 10 to 15 

 volumes of artif. gast. juice, and note effect. 



(^) Subject bread to the xanthoproteic test. The 

 presence of proteid material is demonstrated. Put 

 a small piece of dry bread into a beaker with gastric 

 juice, and note effect. 



(<:) Note the course of casein digestion, 



(</) Triturate in a mortar well cooked lean meat; di- 

 gest with gastric juice. 



(e) Try the xanthoproteic test upon cooked beans or 

 peas; proteid is present. Triturate in a mortar; di- 

 gest. 



(/) In each case, demonstrate the ultimate appear- 

 ance of peptone. 



180 



