DIGESTION AND ABSORPTION ]71 



(10) The Influence of Division upon the Time Required to Digest 

 Proteids. Boil an egg five to ten minutes; cool quickly; separate hard, 

 coagulated white from yolk and envelopes. 



(a) Cut out one-centimetre cube and put it into a beaker with 

 40 c.c. artificial gastric juice. 



(b) Put into a second beaker of 40 c.c. gastric juice a centimetre 

 cube which has been divided into eight half-centimetre cubes. 



(c) Prepare another beaker in which are sixteen quarter-centimetre 

 cubes in 10 c.c. of artificial gastric juice. 



(d) Into another beaker with 10 c.c. of artificial gastric juice put 

 one-quarter of a cubic centimetre of the egg albumin which has 

 been finely divided by pressing through a fine sieve. 



Note time required in each case to completely digest the albumin. 

 Has this any hygienic bearing? 



(11) The Influence of Temperature upon the Time Required to 

 Digest Proteids. Prepare five tubes by first providing each with 

 5 c.c. of artificial gastric juice; treat the several tubes as follows: 



(a) Bring to 40 C. in water-bath; add fibrin; note time. 



(b) Bring to 30 C. in water-bath; add fibrin; note time. 



(c) Bring to 20 C. in incubator; add fibrin; note time. 



(d) Leave at room temperature (10 C.); note time. 



(e) Bring to C. in ice-water; add fibrin; note time. 

 What is the optimum temperature? 



Is the progress of digestion materially retarded by a reduction of 

 the temperature? 



Would the temperature of the stomach contents be essentially 

 lowered by the occasional sipping of an iced beverage during a meal ? 



What is the hygienic significance of the experiment? 



VII. GASTRIC DIGESTION (Continued). 



Experiments and Observations (Continued). (12) The Steps of 

 Gastric Digestion. Boil an egg five to ten minutes; cool quickly; 

 separate out the white; press it through a fine sieve; put into a 

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

 in a water-bath at 40 C. At intervals of two minutes for the first 

 ten minutes, then at intervals of five minutes for the next twenty 

 minutes, then at intervals of ten minutes for the second half-hour, 

 afterward at intervals of one hour, subject the liquid to tests for 

 egg albumin, for acid albumin, far albuinose, 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? 



(13) The Artificial Digestion of Various Proteids. (a) To a small 

 mass of jellied gelatin add ten to fifteen volumes of artificial gastric 

 juice and note effect. 



