SENSATIONS OF SMELL AND TASTE 501 



in which there was a lesion destroying the fifth nerve, the glossopharyngeal 

 being intact. It seems possible that the actual region of the taste-nerve 

 may vary, the fibres running to the splanchnic column of grey matter 

 being contained sometimes in the fifth, sometimes in the glossopharyngeal, 

 and sometimes in both. 



Most of our so-called tastes should rather be designated flavours, and 

 are dependent, not on the gustatory nerves, but on the sense of smell. 



G&sseri'^n Ganglion 



FIG. 245. Diagram showing origin and course of the nerve fibres of taste. 



When the olfactory sense is destroyed very little difference is to be perceived 

 between an onion and an apple. The epicure with a fine palate has really 

 educated his sense of smell and would be but little satisfied with the simple 

 sensations derived from his four sets of gustatory end-organs. 



THE SENSE OF SMELL 



The psychical analysis of olfactory sensations is rendered difficult 

 by the fact that this sense in man plays but a small part in his usual adapta- 

 tions. We have thus to deal with a sense which is in many respects vestigial. 

 We see traces of great complexity in its possibilities of performance, but 

 are baffled in our endeavours to reduce the whole of the phenomena to the 

 simpler factors of which they are composed. Moreover, like all vestigial func- 

 tions, the extent to which the sense is developed varies from one individual to 

 another. Many, for instance, are unable to appreciate the smell of vanilla, 

 of hydrocyanic acid, or of violets. On the other hand, in animals, such as 

 the dog, the olfactory sense seems to play a great part in determining 

 behaviour, and the nervous associations, which are the physiological basis 

 of ideas, must in these animals be largely connected with olfactory im- 

 pressions. Another factor which diminishes the importance of olfactory 

 sensations in man is the ease with which the sense-organ becomes fatigued. 

 It often happens that the inmates of a room are perfectly comfortable 



