556 THE NERVOUS SYSTEM. 



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, perhaps, may be 

 ascribed the more complete and general loss of the sense of 

 taste when the whole of the fifth nerve has been para- 

 lysed. . 



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, but retained 

 both in all the rest of the tongue. M. Lisfranc and others 

 have noted similar cases; and the phenomena in them 

 are so simple and clear, that there can scarcely be any 

 fallacy in the conclusion that the lingual branches of both 

 the fifth and the glosso-pharyngeal nerves are gustatory 

 nerves in the parts of the tongue which they severally 

 supply. 



This conclusion is confirmed by some experiments on 

 animals, and, perhaps, more satisfactorily as concerns the 

 sense of taste in man, by observation of the parts of the 

 tongue and fauces, in which the sense is most acute. Ac- 

 cording to Valentin's experiments made on thirty students, 

 the parts of the tongue from which the clearest sensations 

 of taste are derived, are the base, as far as the foramen 

 crccum and lines diverging forwards on each side from it ; 



