CH. LII.] 



NERVES OF TASTE. 



707 



tongue, but especially over the middle of the dorsum. They vary 

 in shape, some being conical (simple or compound) and others 

 filiform ; they are covered by a thick layer of epithelium, which is 

 either arranged over them, in an imbricated manner, or is pro- 

 longed from their surface in the form of fine stiff projections 



Fig. 528. Vertical section of a circumvallate papilla of the calf, i and 3, epithelial layers 

 covering it ; 2, taste-buds ; 4 and 4', duct of serous gland opening out into the pit 

 in which papilla is situated ; 5 and 6, nerves ramifying within the papilla. 

 (Engelmann.) 



(fig. 530.) From their structure, it is likely that these papillae' 

 have a mechanical and tactile function, rather than that of taste ; 

 the latter sense is seated especially in the other two varieties 

 of papillae, the circumvallate and the fungiform. 



Pig. 529. Surface and section of the fungiform papillae. A, the surface of a fungiform 

 papilla, partially denuded of its epithelium ; p, secondary papillte ; e, epithelium. B, 

 section of a fungiform papilla with the blood-vessels injected ; a, artery ; v, vein ; 

 e, capillary loops of similar papilla* in the neighbouring structure of the tongue ; d, 

 capillary loops of the secondary papillee ; r, epithelium. (From Kulliker, after Todd 

 and Bowman.) 



In the circumvallate papillee of the tongue of man peculiar 

 structures known as taste-buds have been discovered. They are 

 of an oval shape, and consist of a number of closely packed, 

 very narrow and fusiform, cells (gustatory cells). This central 



zz 2 



