444 INNEKVATION. [CHAP. xv. 



Evidence from Experiments. From observations on the effects of 

 section of the glosso-pharyngeal nerves in dogs, Panizza, and, sub- 

 sequently, Valentin and Wagner, concluded that taste was completely 

 lost after their division, and, consequently, that these are the sole 

 nerves of the sense. But in such an inquiry negative results have far 

 less value than positive ones ; and we therefore consider the experi- 

 ments of Miiller, Gurlt, and Kornfeld, and those of Alcock and Reid, 

 who all agree that decided indications of taste remained after these 

 nerves had been cut, as proving that the lingual branches of the fifth 

 share in the sense. Miiller, Gurlt, and Kornfeld, however, failing to 

 find signs of taste after the lingual branches of the fifth were divided, 

 concluded too hastily that these are the sole, or by far the principal 

 nerves of the sense, in opposition to the experiments of Panizza and 

 his followers, the positive evidence of which in this regard carries 

 greater weight. The experiments of Dr. Alcock directly tend to 

 reconcile these inconsistencies. He found that though taste re- 

 mained after dividing the lingual branches of the fifth, yet it 

 seemed completely lost in the anterior part of the tongue. Besides, 

 it is not impossible that the rude injury inflicted in these contradic- 

 tory experiments on either of the glosso-pharyngeal or the lingual 

 branch of the fifth might temporarily deaden the sense of taste in the 

 other, in away somewhat similar to that, whatever it might be, in which 

 loss of smell impairs taste. Valentin admits that one of the dogs in 

 which he had cut the glosso-pharyngeal nerves was able to taste a fort- 

 night afterwards ; a period quite too short to have allowed reunion 

 and restoration of function to the nerves, and making it likely that 

 the sense had been only apparently, and not really lost. 



Evidence from Disease. In some cases loss of common sensation 

 consequent on disease of the fifth nerve has been reported as being 

 attended with loss of taste;* in others, taste appears to have been 

 preserved : f on the other hand, taste has been sometimes lost while 

 common sensation in the tongue remained. J We would interpret the 

 apparently contradictory evidence of these cases by one which we 

 have ourselves lately witnessed, and which will be found to accord 

 remarkably with the foregoing views. A middle-aged man suffered 

 for eight years from complete loss of sensation in all parts supplied 

 by the fifth nerve on the left side, with the exception of the forehead. 

 The left eye was lost by destructive inflammation : the tongue was 

 quite without feeling on the left side. On experimenting on his sense 



* Bishop, Med. Gaz. 1833 ; Eomberg, Miiller's Archiv. 1838, Heft iii. 

 t Noble, Med. Gaz. vol. xv. p. 120 ; Vogt, Miiller's Archiv. 1840, p. 72. 

 J Noble, Med. Gaz. vol. xvi. 



