642 



SPECIAL SENSES 



glosso-pharyngeal by electricity inhibits respiration for a short time. 



This action is reflex. 



Relations of the Glosso-Pharyngeal Nerves to Gtistation. Relying 



on experiments on the inferior animals, particularly dogs, it seems 



certain that there are 

 two nerves presiding 

 over the sense of 

 taste : The chorda- 

 tympani nerve gives 

 this sense to the 

 anterior two-thirds of 

 the tongue exclusive- 

 ly ; and the glosso- 

 pharyngeal supplies 

 this sense to the pos- 

 terior portion of the 

 tongue. The chorda 

 tympani seems to 

 have nothing to do 

 with general sensibil- 

 ity ; while the glosso- 

 pharyngeal is an or- 

 dinary sensory nerve, 

 as well as a nerve 

 of special sense. 



MecJianism of Gus- 

 tation. Articles that 

 make the special im- 

 pression on the gus- 

 tatory organ are in 

 solution ; introduced 



Fig- I 59- Papilla of the tongue (Sappey). into the mouth, they 



I, I, circumvallate papillae; 2, median circumvallate papilla, which increase the flow of 



entirely fills the foramen caecum; 3, 3, 3, 3, fungiform papillae; 4,4, ,. , ^ 



filiform papillse; 5, 5, vertical folds and furrows of the border of the Saliva, the rettCX ac- 



tongue; 6, 6, 6, 6, glands at the base of the tongue; 7, 7, tonsils; fcjon involving chiefly 



8, epiglottis ; 9, median glosso-epiglottidean fold. . 



the submaxillary and 



sublingual glands ; there usually is more or less mastication, which 

 increases the flow of the parotid saliva ; and during the acts of mas- 

 tication and the first stages of deglutition, the sapid substances are 

 distributed over the gustatory membrane, so extensively, indeed, that 

 it is difficult to locate exactly the seat of the special impression. In 

 this way, by the movements of the tongue, aided by an increased flow 



