100 CONSCIOUS NERVOUS OPERATIONS 



43. Varieties of Tastes. Wipe the tongue dry and place on its 

 tip a crystal of sugar. It is not tasted until it dissolves. Place a 

 crystal of sugar on the tip and another on the back of the tongue. 

 The sweet taste is more evident at the tip. Repeat the process, using 

 a strong solution of quinine sulphate dissolved in water by aid of 

 a little sulphuric acid. The bitter taste is most pronounced on the 

 back of the tongue. In a similar way determine where acids and 

 salts are tasted, using a 1 per cent solution of acetic acid and a 10 per 

 cent solution of common salt respectively. 



44. Organs of Smell. The turbiuated processes of the human 

 ethmoid and maxillary bones, or those of some of the domestic 

 animals, should be accessible to the pupil for examination, as they 

 show how a great deal of surface in a small space is provided for the 

 olfactory membrane. The teacher should perform such dissections 

 upon the head of some one of the domestic animals as to show the 

 olfactory epithelium, the exterior nasal passages, and the posterior 

 passages opening into the pharynx. 



45. Combination of Taste with Smell. Close the nostrils, shut the 

 eyes, and try to distinguish by taste alone between an apple, a potato, 

 and an onion. Chew a grain of roasted coffee and notice how nearly 

 tasteless it becomes when the nostrils are closed. 



46. Fatigue of Smell. For several minutes smell continuously of 

 a piece of camphor gum, breathing in through the nose and out through 

 the mouth. The intensity of the smell becomes much lessened. But 

 if some other odoriferous substance, as clove oil, is brought near the 

 nostrils, it will be found that the fatigue is only for the odor of 

 camphor. 



