THE DIGESTION OF STARCH. 



37 



ft, make a small opening with a knife, and col- 

 lect the bile in a bottle. (The bile of herbiv- 

 orous animals is green in color; human bile 

 when fresh is a golden-brown liquid.) 



A solution of solid ox-gall in water may be 

 used instead of the contents of the gall-blad- 

 der, if the latter cannot be easily obtained. 



19. THE DIGESTION OF STARCH. 



Materials: Corn-starch, saliva, pancreatin solution; test-tubes; 

 alcohol-lamp. 



A. By saliva. 



Put a small amount of corn-starch in a test- 

 tube, add water and boil ; dilute the paste until 

 a smooth, thin mixture is formed. 



1. Pour into a test-tube a small amount of this 



starch mixture, and test with Fehling's 

 solution. What is the result and what 

 is your conclusion? 



2. Allow some saliva to flow from the mouth 



into a clean test-tube ; * test it with Feh- 

 ling's solution. What is your inference? 



3. Pour some saliva into the starch paste made 



at the beginning of the experiment, shake 

 the mixture and warm gently for a mo- 

 ment or two. Test with Fehling's solu- 

 tion. Result? 

 ... What is the effect of saliva on boiled starch? 



* Saliva sufficient for the class may be obtained by the teacher be- 

 fore the exercise. 







