134 LABOEATOEY MANUAL 



tive? Least sensitive? Where are the hot spots most 



numerous? Where are the cold spots most numerous? 



C. Do we derive any sensations other than touch and 



temperature through the skin? If so, what are they? 



Exercise 90. Organs of Taste and Smell. 

 Object: A study of the tongue and the sensations of 

 taste and smell. 



Apparatus 



Sugar Quinine 



Salt Onion 



Vinegar 



Directions: A. With the aid of a mirror examine 

 the upper and lower surfaces of the tongue. What 

 differences do you note? The raised points on the 

 upper surface are called papillae. Observe that they 

 are of three forms : long and slender, filiform; small, 

 red, mushroom shaped spots, fungi form; far back 

 on the tongue the large circumvallate papillae. How 

 many of them can you see? Draw an outline of the 

 tongue, and locate on it the regions where these dif- 

 ferent forms are to be found. 



B. Place some sugar on the tip of the tongue. Let 

 it dissolve. Has it any taste? Repeat, placing the 

 sugar at the back of the tongue. Is its sweetness more 

 or less prominent? Repeat again, using quinine, 

 vinegar, and salt successively. Where are the sensa- 

 tions of bitterness, sourness, sweetness, and saltiness 

 most prominent? 



C. The sense organs of smell are located in the 



