126 



SMELL, TASTE, ALLIED SENSES 



the temporary disturbance in taste, a condition that was 

 supposed to be permanent by Krause, to the effect of the 

 degenerating trigeminal fibers on the adjacent gusta- 

 tory fibers, an effect that disappeared when the degenera- 

 tion was complete. Consequently Gushing concluded that 

 the gustatory fibers from the anterior part of the tongue 



VII 



FIG. 35. Diagram to illustrate the possible paths of the gustatory nerve-fibers from the 

 tongue to the brain in man. The distal part of the tongue (1) is innervated by the lingual 

 nerve (2) whose gustatory fibers pass to the brain by way of the chorda tympani (3), a 

 branch of the facial nerve (VII). The proximal part of the tongue is innervated^ by the 

 glossopharyngeal nerve (4). The undoubted gustatory paths over the facial nerve (VII) and 

 the glossopharyngeal nerve (IX) are indicated by dotted lines. The commonly assumed 



Eaths by way of the trigeminal nerve (V) are shown in heavy black lines with arrows. Modi- 

 ed from Cushing, 1903. 



are not part of the trigeminal nerve. If this is so, they 

 must belong to the facial or possibly to the glossopharyn- 

 geal nerve (Fig. 35). That they are abundantly present 

 in the chorda tympani of the facial nerve is well known 

 from the fact that direct stimulation of the chorda in 

 the neighborhood of the ear drum is commonly accom- 

 panied by sensations of taste, but whether these gusta- 

 tory fibers on reaching the facial nerve pass into the brain 

 through its root or make their way to the root of the glos- 

 sopharyngeal is not yet definitely settled. It is, therefore, 

 probable that in mammals the trigeminal nerve, though 



