124 



SMELL, TASTE, ALLIED SENSES 



In the fishes the nerves chiefly concerned are the vagus, 

 the glossopharyngeal and the facial. The taste-buds of 

 the gill region are supplied by the vagus and the glosso- 

 pharyngeal. Those that are in the mouth proper or are 

 on the exterior of the body are innervated by the facial 

 nerve. Consequently in the catfish (See Fig. 28), in 



which the whole outer 

 skin is provided with 

 taste-buds, this nerve is 

 enormously developed and 

 sends large branches to 

 the barbels and an exten- 

 sive recurrent branch to 

 the flanks of the bod)^ 

 (Herrick, 1903). 



In mammals, includ- 

 ing man, the innervation 

 of the taste-buds is not 

 upon so simple a plan as in fishes. In these higher 

 vertebrates gustatory fibers may possibly be contained 

 in four of the cranial nerves, the vagus, the glosso- 

 pharyngeal, the facial, and the trigeminal. The 

 distribution of these nerves in the human tongue has been 

 worked out by Zander (1897). Certain parts of the 

 vagus are distributed to the larynx and to the epiglottis 

 as well as to the most posterior part of the tongue itself 

 and innervate very probably the taste-buds of these re- 

 gions (Fig. 34). The glossopharyngeal supplies the pos- 

 terior third of the tongue including the foliate and vallate 

 papillag, for, as was first shown by von Vintschgau and 

 Honigschmied (1876), when the ninth nerve is cut the 

 taste-buds of these parts soon degenerate and disappear. 

 Although the correctness of this observation was denied 



Fig. 33. — Golgi preparations of the taste- 

 budR of the common European barbel show* 

 ing cells and nerve-fibera. After von Lenhoss^k, 

 1893 a, Fig. 2. 



