;o8 



TASTE AND SMELL. 



[CH. LII. 



core of gustatory cells is enclosed in a single layer of broader 

 fusiform cells (encasing cells). The gustatory cells terminate in 

 fine stiff spikes which project on the free surface (fig. 531, a). 

 These bodies also occur side by side in considerable numbers 



in the epithelium of the 

 papilla foliata, which is 

 situated near the root of 

 the tongue in the rabbit, 

 and is composed of a 

 number of closely packed 

 papillae very similar in 

 structure to the circum- 

 vallate papillae of man. 

 Taste-buds have also 

 been observed scattered 

 over the posterior third 

 of the tongue and the 

 pharynx, as low as the 

 posterior (la ryngeal) sur- 

 face of the epiglottis. 



The gustatory cells in 

 the interior of the taste- 

 buds are surrounded by 

 arborisations of the ter- 

 minations of the glosso- 

 pharyngeal nerve. 



The middle of the 

 dorsum of the tongue is 

 not endowed to any great 

 degree with the sense of 

 taste ; the tip and mar- 

 gins, and especially the 

 posterior third of the 

 dorsum (i.e., in the region 

 of the taste-buds), pos- 

 sess this faculty. The 

 anterior part of the 

 tongue is supplied by the lingual branch of the fifth nerve and the 

 chorda tympani, and the posterior third by the glosso-pharyngeal 

 nerve. Considerable discussion has arisen whether there is more 

 than one nerve of taste. The view generally held by physiologists 

 is that the glosso-pharyngeal nerve is the nerve of taste, and the 

 lingual the nerve of tactile sensation. Nevertheless, the lingual 

 and the chorda tympani do contain taste-fibres, which may be, 



Fig. 530. Filiform papillae, one with epithelium, 

 the other without. *f . p, the substance of the 

 papillss dividing at their upper extremities into 

 secondary papillee ; a, artery, and v, vein, dividing 

 into capillary loops ; , epithelial covering, lami- 

 nated between the papillae, but extended into 

 hair-like processes, /, from the extremities of the 

 secondary papillae. (From Kolliker, after Todd 

 and Bowman.) 



