MECHANISM OF OLFACTION. 35 



fossce. " While this is the case the man is completely unable 

 to smell or to distinguish flavors, though he can still perfectly 

 recognize true tastes, viz., sweet, salt, acid, bitter. This is 

 his usual condition. But by an effort he is able momentarily 

 to open the passage behind the velum, and when he does this 

 he can for the time both smell and recognize flavors." ] 



It is a curious point to determine whether the sense of 

 smell be affected by odors passing from within outward 

 through the nasal fossae. Persons who have offensive emana- 

 tions from the respiratory organs usually are not aware, from 

 their own sensations, of any disagreeable odor. This fact is 

 explained by Longet on the supposition that the olfactory 

 membrane becomes gradually accustomed to the odorous im- 

 pression, and therefore it is not appreciated. This is an ap- 

 parently satisfactory explanation, for we could hardly sup- 

 pose that the direction of the emanations, provided they came 

 in contact with the membrane, could modify their effects. 

 He cites a case of cancer of the stomach, in which the vom- 

 ited matters were exceedingly fetid. At first, the patient, 

 when he expired the gases from the stomach through the 

 nostrils, perceived a disagreeable odor at each expiration ; but 

 little by little this impression disappeared. 2 



Relations of Olf action to the Sense of Taste. The rela- 

 tions of the sense of smell to gustation are very intimate. In 

 the appreciation of delicate shades of flavor, it is well known 

 that the sense of olfaction plays so important a part, that it 

 can hardly be separated from gustation. The common prac- 

 tice of holding the nose when disagreeable remedies are swal- 

 lowed is another illustration of the connection between the 

 two senses. In most of the cases of anosmia already referred 

 to, reported by Notta and by Ogle, coincident with the loss 

 of smell, there was inability to distinguish delicate flavors. 

 The patients could only distinguish by the taste, sweet, saline, 



1 OGLE, Anosmia. Medico- Chirurgical Transactions, London, 1870, p. 273. 



2 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 49. 



