262 ELEMENTARY PHYSIOLOGY. [XXV. 



a distinct sensation of taste will be felt, of acidity 

 at the positive pole (anode), of alkalinity at the 

 negative pole (kathode). 



Keeping the electrodes at the same distance, say 

 two or three millimetres, determine the amount 

 of taste-sensation in different parts of the mouth. 

 It will be greatest at the tip and back (region of 

 circumvallate papillae) of the tongue, and edges 

 of the tongue ; least or absent in the anterior 

 and middle surface, under surface of the tongue, 

 and lips. The soft palate will be found to be 

 highly sensitive, the hard palate little or not 

 at all. 



4. Take two small pieces of sugar of equal size, and 

 place one on the tip, and the other on the back 

 of the tongue ; the sensation will be most acute 

 at the tip. 



5. Place a crystal of sulphate of quinine on the tip 

 of the tongue ; it will hardly be tasted. Place 

 it on the back ; it will be tasted at once. 



