SMELL 297 



they are connected with the olfactory cells whose axis 

 cylinders pass through the cribriform plate to the bulbus 

 olfactorius (see page 250). 



Adequate stimuli for the organ of smell are gases carried 

 through the nose by inspiration and diffused in the regio 

 olfactoria. 



The liminal intensity of many substances is very small ; 

 I millionth of I milligram of musk or butyric acid in I litre 

 of air can be detected by the sense of smell, while of mer- 

 captan still less is necessary. 



The organ of smell is very soon fatigued. 



The sensations of smell have many different qualities 

 which have not yet been classified. Mixed odors are pro- 

 duced by the action of two or more odorous substances. 

 Some odors are able to neutralize each other. 



Corrosive gases cause tactile sensations in the nasal mucous 

 membrane which may be accompanied by sensations of smell. 



