EXERCISE 58 



Digestion of food in the human body takes place in (i) the mouth, (2) the stomach, and (3) the 

 intestine. In each of these spaces there is at work a special digestive fluid : (i) the saliva, containing the 

 ferment ptyalin ; (2) the gastric, or stomach, juice, containing the ferment' pepsin ; and (3) the pancreatic 

 juice, containing several ferments. 



Problem. Which of the digestive fluids acts upon protein ? 



What to use. Pieces of egg albumen 1 ; some saliva 2 ; a solution of pepsin ; a solution of pancreatin ; 

 test tubes ; water ; absorbent cotton. 



What to do. Place in the test tubes strips of albumen of about the same size. In one tube place 

 water ; in the second, saliva ; in the third, pepsin solution ; in the fourth, pancreatin solution. Close 

 tubes with cotton plugs. Place all in a warm place overnight ; note changes in the egg every day until 

 one of the pieces is definitely eaten away. 



Record. Indicate in the appropriate spaces the amount of change produced day by day in each tube. 



Questions. 1. What solutions brought about the digestion of protein ? 



2. Which solution acted most quickly ? 



3. In what parts of the body may proteins be digested ? 



1 From the white part of a hard-boiled egg thin strips are cut with a sharp knife. 



2 See Note, Exercise 56. 



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