vii THE MEDULLA OBLONGATA 401 



relations between respiratory and cardiac rhythm returned. But 

 when shown at the Congress the animal was still incapable of 

 making any sounds, and vomited frequently, though well nourished 

 and in good spirits. After anaesthetising it with ether and 

 chloroform, Pawlow and Steward exposed the two nerve trunks, 

 which were found to be already united by cicatricial tissue, but 

 not regenerated, since strong electrical stimulation below the 

 point of section did not affect the rhythm of the heart, although 

 above that point it produced acceleration of the respiratory rhythm. 



Both Boddaert's case and that of Gomez Ocafia show that, 

 although important, the functions of the vagus nerves are not 

 absolutely indispensable to life. How the disorders of respiratory 

 and cardiac rhythm, of deglutition and of phonation, which neces- 

 sarily result from double vagotomy can be compensated remains a 

 mystery. 



V. The Glosso-pharyngeal or 9th cerebral nerve leaves the 

 medulla oblongata by two roots, one of which, the motor, arises 

 along with the vagus from the nucleus ambiguus, the other, which 

 is sensory, has its terminal nucleus above that of the vagus, on the 

 floor of the fourth ventricle, in the ala cinerea (see Fig. 204). It 

 is therefore a mixed nerve, and may be regarded as a metameric 

 homologue of a spinal pair. In its passage through the jugular 

 foramen, along with the vagus and accessory, it bears two small 

 ganglia, the jugular and petrosal, which have unipolar cells like 

 the spinal ganglia. The petrosal ganglion gives origin to the 

 tympanic branch (Jacobson's nerve), which connects the glosso- 

 pharnygeal with other nerves at the base of the skull (Fig. 211). 



In passing through the neck the glosso-pharyngeal gives off a 

 pharyngeal branch, a tonsillar branch which also innervates the 

 mucous membrane of the pillars of the fauces and the soft palate, 

 and lingual branches that supply the circumvallate and foliate 

 papillae of the mucous membrane over the posterior two-thirds of 

 the tongue (Fig. 212). 



Before the publication of Panizza's classical memoir, Experi- 

 mented Researches on Nerve (1834), Fodera, Mayo, and Magendie 

 had maintained that the sense of taste was subserved entirely by 

 the lingual branch of the trigeminal. Panizza was the first who 

 demonstrated that the glosso-pharyngeal is the taste nerve, just 

 as the lingual branch of the trigeminal is the tactile nerve, and 

 the hypoglossal the motor nerve, for the tongue. 



Panizza's assertion of the exclusively gustatory character of 

 the glosso-pharyngeal was at once contested by Joh. Mliller and 

 his pupil Kornfeld, who believed this nerve to be of little import- 

 ance for taste, that sense being served by the lingual nerve, as 

 Magendie stated. Other physiologists came to the same conclusion 

 (Hall and Braughtori, Wagner, Valentin, Stannius) on repeating 

 Panizza's experiments ; and others recognised the glosso-pharyngeal 



VOL. in 2 D 



