viz THE MEDULLA OBLONGATA 403 



and the chorda tympani are of no importance for the sense of 

 taste, since they can be extirpated or divided without disturbing 

 it. Guzot and Cazalis (1839) concluded from their researches 

 that the lingual was the tactile and gustatory nerve for the anterior 

 three-fourths of the tongue. Eeid (1839) added that after bilateral 

 section of the glosso-pharyngeal the sense of taste was sufficiently 

 well preserved to distinguish bitter substances. 



On the other hand, 01. Bernard (1843) found that after 

 dividing the facial nerve in the cranial cavity, or cutting the 

 chorda in the tympanic cavity, the taste sense is altered in the 

 anterior part of the tongue, because savours are less promptly 

 recognised than on the side not operated on. 



Biffi and Morganti (1846), after unilateral section of the 

 chorda, failed to confirm the difference in the sense of taste on 

 the two halves of the tongue. It further appeared from their 

 experiments that the glosso-pharyngeal is the nerve of taste for 

 the palate, fauces, and posterior two-thirds of the tongue, while 

 the lingual branch serves its anterior third. 



Duchenne (1860) brought evidence in favour of Bernard's 

 theory of the presence of taste fibres in the chorda tympani by 

 exciting them electrically through the external auditory meatus. 

 This, according to Duchenne. produces, in addition to sensory 

 phenomena, a metallic taste in the anterior two -thirds of the 

 tongue ; while electrical stimulation of the lingual nerve^on the 

 other hand, does not produce any sense of taste. 



According to Schiff (1867), the taste fibres for the anterior 

 part of the tongue, which leave the bulb with the second branch 

 of the trigeminal, run to the spheno-palatine ganglion, thence by 

 the Vidian nerve to the geniculate ganglion of the facial, and 

 finally join the trunk of the inferior maxillary nerve, or run in 

 the facial to the chorda tympani, and thence to the lingual. This 

 theory, however, is at variance with the fact established by Alcock, 

 and subsequently confirmed by Prevost, that the extirpation of the 

 spheno-palatine ganglion produces no perceptible alteration in 

 taste. 



Lussana and Inanzi (1862) fell back on Bernard and Duchenne's 

 hypothesis. They maintained that the taste fibres to the anterior 

 part of the tongue come from the facial or the intermediary nerve 

 of Wrisberg, and pass to the geniculate ganglion, thence by the 

 facial trunk to the chorda tympani and to the lingual. In addition 

 to his experimental data, Lussana based his view upon clinical 

 cases of paralysis of the trigeminus without loss of taste on the 

 anterior part of the tongue, and of paralysis of the facial nerve 

 or lesions of the chorda tympani in man, with abolition of taste 

 in this region. To this it was objected that in facial paralysis 

 the sense of taste disappears from the tip of the tongue only if 

 the lesion lies between the geniculate ganglion and the exit of the 



