IV 



THE SENSE OF SMELL 



161 



relates that the Indians of Peru are capable of perceiving and 

 following up the scent of game like hunting - dogs. This is 

 probably due to the fact that they preferably use and educate 

 their olfactory sense. Exercise, in fact, perfects the sense of 

 smell to a remarkable extent ; pharmacists are able to recognise 

 drugs and their various properties by smell alone; experienced 



FIG. 62. Frontal section of nasal fossae, seen from behind ; the section passes through the back 

 molars. (Testut.) 1, nasal septum; 2, upper; 3, middle; 4, lower turbinals ; 5, posterior 

 ethmoid cells opening into 5' (to the right), superior meatus ; 6, maxillary antrum opening 

 into 6', middle meatus ; the point of the arrow is in the hiatus semi-lunaris ; 7, bulla 

 ethmoidalis ; 8, frontal sinus ; 9, crista galli ; 9', falx cerebri ; 10, cerebral hemispheres ; 

 11, right orbit surrounded by orbital fat, with eye-muscles ; 12, great ala of sphenoid ; 13, 

 spheno-maxillary cleft ; 14, adipose tissue of zygomatic fossa ; 15, buccinator muscle ; 1(5, last 

 molar ; 17, vault of palate ; 18, zygoma ; 19, left orbit. 



physicians diagnose many eruptive diseases at once by their odour ; 

 by it wine and oil merchants know the good and bad qualities of 

 their stock-in-trade. Wardrop tells of a man born blind and 

 deaf who distinguished his acquaintances by their smell. 



I. The specific olfactory sensory region consists of a limited 

 portion of the mucous membrane of the nasal fossae. Seen in 

 transverse section (Fig. 62) the nasal fossae appear as an irregular 



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