58 EXPERIMENTAL PHYSIOLOGY 



dissolving the solid pancreatin powder in water. For fats 

 add to this the sodium carbonate solution in the same way 

 as to the glycerine solution. 



D. Bile. Open and extract the contents of an ox gall 

 or dissolve prepared ox gall in water. 



E, Temperature Conditions. To obtain the best results in 

 all artificial digestion experiments keep the materials used 

 as near a constant temperature as is possible. For this 

 purpose it is suggested that a constant temperature water 

 bath be used, if possible. If this is unavailable an ordinary 

 drying oven may be used with an Argand burner. Another 

 substitute is a double boiler, — such as is used in cookery, — 

 with the Argand burner. Place in test tubes the fluids and 

 materials to be digested. Cover the inner chamber of the 

 double boiler with a wooden cover having holes bored to 

 fit the test tubes, and suspend the tubes in these. Heat 

 the water in the outer part to the temperature desired 

 and adjust the Argand burner to maintain just that temper- 

 ature. 



XXXVI. — Digestion of the Mouth — Saliva. 



Apparatus, — A little salt, dry cracker, dilute starch paste, white 

 of egg, olive oil, saliva, litmus paper, Fehling's solution, concentrated 

 hydrochloric acid, test tubes, constant temperature apparatus. 



Directions. — A. General Functions of Saliva. Clear the 

 mouth of saliva by swallowing, and wipe dry the top of the 

 tongue. Place on the tongue a bit of salt. Can you taste 

 the salt? Close the mouth, letting the salt stay on the 

 tongue. What happens in the mouth? Where does the 

 saliva come from in the mouth? Where is it made? Was 

 the presence of the salt on the tongue sufficient to cause its 



