556 THE NERVOUS SYSTEM. 



these actions ; yet not the only one, for, as Dr. John Reid 

 has shown, the acts are scarcely disturbed or retarded 

 when both the glosso-pharyngeal nerves are divided. 



But besides being thus a nerve of common sensation in 

 the parts which it supplies, and a centripetal nerve through 

 which impressions are conveyed to be reflected to the 

 adjacent muscles, the glosso-pharyngeal is also a nerve 

 of special sensation ; being the gustatory nerve, or nerve of 

 taste, in all the parts of the tongue to which it is distri- 

 buted. After many discussions, the question, which is 

 the nerve of taste ? the lingual branch of the fifth, or the 

 glosso-pharyngeal ? may be most probably answered by 

 stating that they are both nerves of this special function, 

 For very numerous experiments and cases have shown that 

 when the trunk of the fifth nerve or its lingual branch is 

 paralysed or divided, the sense of taste is completely 

 lost in the superior surface of the anterior and lateral 

 parts of the tongue. The loss is instantaneous after 

 division of the nerve ; and, therefore, cannot be ascribed 

 to the defective nutrition of the part, though to this, per- 

 haps, may be ascribed the more complete and general loss 

 of the sense of taste when the whole of the fifth nerve has 

 been paralysed. 



But, on the other hand, while the loss of taste in the part 

 of the tongue to which the lingual branch of the fifth 

 nerve is distributed proves that to be a gustatory nerve, 

 the fact that the sense of taste is at the same time 

 retained in the posterior and postero -lateral parts of the 

 tongue, and in the soft palate and its anterior arch, to 

 which (and to some parts of which exclusively) the glosso- 

 pharyngeal is distributed, proves that this also must be a 

 gustatory nerve. In a female patient at St. Bartholomew's 

 Hospital, the left lingual branch of the fifth nerve was 

 divided in removing a portion of the lower jaw : she lost 

 both common sensation and the sensation of taste in the 

 tip and the anterior parts of the left half of the tongue, 



