SENSE OF TASTE. 



407 



quently, the chorda tympani, according to Schiff, consists of bor- 

 rowed fibres proceeding from the trifacial to the facial nerve, a 

 lesion or entire section of the trifacial, before its division into three 

 branches, producing the same effect on the taste as section of the 

 chorda tympani. 



By accepting this conclusion, however, we only place the diffi- 

 culty a little farther back ; for the new question immediately arises, 

 where and how does the facial nerve borrow from the trifacial the 

 sensory fibres which are destined to form the chorda tympani? 



Schiff inclines to the belief that in the large petrosal nerve an 

 anastomosis takes place, by means of which the facial nerve bor- 

 rows from the trifacial the sensory fibres which lead to the tongue. 

 So much controversy is still going on in regard to these results 

 that we refrain from giving the details of the experiments under- 

 taken for the purpose of proving these theories. We will simply 

 sum up in a diagram the theories of Lussana and of Schiff. In 



the figures 105 and 106, G represents the Gasserian ganglion, 

 developed on the trifacial (III) , which then divides into the ophthal- 

 mic (1), the superior maxillary (2), and the inferior maxillary (3) ; 

 L represents the lingual nerve; VII, the facial; i, the intermediate 

 nerve of Wrisberg; GT, the chorda tympani; Gg, the genicu- 

 late ganglion. AVe see that, in Lussana's hypothesis (Fig. 105), 

 the gustatory fibres, the course of which is represented by a dotted 

 line, pass from the tongue to the nerve centres through the lin- 

 gual nerve (L), the chorda tympani (CT), the facial nerve, and, 

 finally, through the intermediate nerve of Wrisberg. On the 

 other hand, Schiff maintains that the paths of conduction of the 

 sensory impressions follow the lingual (L, Fig. 107), the chorda 

 tympani (CT), and the facial nerve (VII); but they leave this 

 nerve at the level of the geniculate ganglion (</), and follow the 

 large petrosal nerve, join the ganglion of Meckel (M), and, conse- 

 quently, the superior maxillary ('J), and, finally, reaches the base 

 of the encephalon by the trunk of the trifacial (III). 



We must, however, add that physiologists by no means gener- 



