174 SENSE OF HEARING. 



Lastly: like the other senses, smell is capable of great improvement 

 by education. The perfumer arrives, by habit, at an accurate discri- 

 mination of the nicest shades of odours ; and the chemist and the 

 apothecary employ it to aid them in distinguishing bodies from each 

 other ; and in pointing out the changes that take place in them, under 

 the influence of heat, light, moisture, &c. In this way, it becomes a 

 useful chemical test. The effect of education is likewise shown, by the 

 difference between a dog kept regularly accustomed to the chase, and 

 one that has not been trained. For the same reason, in man, the sense 

 is more exquisite in the savage than in the civilized state. In the latter, 

 he can have recourse to a variety of means for discriminating the proper- 

 ties of bodies ; and hence has less occasion for acuteness of smell than 

 in the former ; whilst, again, in the latter state, numbers destroy the 

 sense to procure pleasure. The use of snuff is one of the most common 

 of these destructive influences. 



Of the acuteness of the sense of smell in the savage we have an 

 example on the authority of Humboldt : he affirms, that the Peruvian 

 Indians in the middle of the night can distinguish the different races 

 by their smell, whether they are European, American, Indian, or 

 negro. To the same cause must be ascribed the delicacy of olfaction 

 generally observed in the blind. The boy Mitchell, 1 who was born 

 blind and deaf, and whose case will have to be referred to hereafter, 

 was able to distinguish the entrance of a stranger into the room by 

 smell alone. A gentleman, blind from birth, from some unaccountable 

 impression of dread or antipathy, could never endure the presence of 

 a cat in the apartment. One day, in company, he suddenly leaped 

 up ; got upon an elevated seat ; and exclaimed, that a cat was in the 

 room, begging them to remove it. It was in vain that the company, 

 after careful inspection, assured him he was under an illusion. He 

 persisted in his assertion and state of agitation ; when, on opening the 

 door of a small closet, it was found that a cat had been accidentally 

 shut up in it. 



SENSE OF HEARING OR AUDITION. 



Audition makes known to us the peculiar vibrations of sonorous 

 bodies, that constitute sounds. It differs from the senses which have 

 already been described, in the fact, that contact is not required between 

 the organ of sense and the sonorous body; or between it and any 

 emanation from the body. It is, however, a variety of touch, but pro- 

 duced by a medium acted upon by the vibratory body. 



1. ANATOMY OF THE ORGAN OF HEARING. 



The auditory apparatus is a subject of intricate study to the young 

 anatomist ; and unfortunately when he has become acquainted with the 

 numerous minute portions to which distinct and difficult appellations 

 have been appropriated, he has, as in many other cases, attained a 

 tedious detail of names, without having added to his stock of physio- 



1 Wardrop's History of James Mitchell, Lond., 1813; and Dugald Stewart's Elements of 

 the Philosophy of the Human Mind, iii. 401, 3d edit., Lond., 180S. 



