154 PHYSIOLOGY OF TASTE. 



of the tongue. Their division does not affect the motions of that organ 

 or its power of taste ; both remain entire. Lastly, when the glosso- 

 pharyngeal nerve is divided, the sense of taste is lost ; whilst, the other 

 nerves being uninjured, motion and tactile sensibility remain. Pro- 

 fessor Panizza found, that when the glosso-pharyngeal nerves were 

 divided, the animal could not taste coloquintida. 



From a series of experiments, however, similar to those of Panizza 

 and Mr. Broughton, Mr. Mayo inferred, in conformity with an opinion 

 previously expressed by him, 1 that the lingual branch of the fifth is the 

 proper nerve of taste, and that it possesses also general sensibility; 

 that the ninth or hypoglossal is the nerve of voluntary motion ; whilst 

 the glosso-pharyngeal is in part a nerve of voluntary motion and in 

 part of general sensibility, but not of taste. 2 Again : the experiments 

 and researches of Dr. John Reid, 3 have satisfied him, that after the 

 perfect section of the glosso-pharyngeal nerves on both sides, the sense 

 of taste is sufficiently acute to enable the animal to recognise bitter 

 substances ; and his inference is, that this nerve may participate with 

 others in the function of taste ; but that it assuredly is not the special 

 nerve of that sense. Prof. J. Muller 4 esteems it certain, both from his 

 own experiments and those of M. Magendie and others, as well as from 

 pathological observations, that the lingual branch of the fifth is the 

 principal nerve of taste of the tongue ; but he does not regard it proved, 

 that the glosso-pharyngeal has no share in the perception of taste at 

 the posterior part of the tongue, and in the fauces. Dr. Carpenter, 5 

 from a consideration of how nearly the sense of taste is allied to that 

 of touch, and bearing in mind the distribution of the two nerves, thinks 

 it not difficult to arrive at the conclusion, that both nerves are concerned 

 in the function ; 6 and that there seems good reason to believe the 

 glosso-pharyngeal to be exclusively that through which the impressions 

 made by disagreeable substances taken into the mouth are propagated 

 to the medulla oblongata, so as to produce nausea, and excite efforts to 

 vomit ; whilst M. Longet 7 regards the lingual branch of the fifth and 

 the glosso-pharyngeal as necessary for the general and special sensibility 

 of the gustatory organs, " the action of the one perfecting that of the 

 other, both as respects the general sensibility and the gustatory sensi- 

 bility of the tongue." It may be proper to add, that experiments seem to 

 show, that the glosso-pharyngeal possesses also a direct motor influence. 

 Such is the inference of Messrs. J. Muller, Volkmann, and Hein. The 

 last observer, whose experiments were carefully performed, states that 

 his results accord completely with those of Volkmann. When the roots 

 of the glosso-pharyngeal nerve were irritated in the recently cut-off 

 heads of calves and dogs, after removing the brain and medulla ob- 



1 Anatomical and Physiological Commentaries, p. 2, Lond., 1822. 



3 Bostock's Physiology, 3d edit., p. 732, Lond., 1836; and Mayo, Outlines of Physiology, 

 4th edit., p. 314, Lond., 1837. 



3 Edinburgh Medical and Surg. Journal, for Jan., 1838, p. 129. See, on this disputed topic, 

 Alcock, in Dublin Journal, for Nov., 1836, and J. Guyot, Archives Generates de Medecine, 

 Janvier, 1837. 



4 Elements of Physiology, by Baly, P. v. p. 1321, Lond., 1839. 



5 Human Physiology, p. 173, and p. 253, Lond., 1842. 



6 Todd and Bowman, The Physiological Anatomy and Physiology of Man, p. 442, London, 

 1845. 



7 Traite de Physiologic, ii. 297, Paris, 1850. 



