112 



SMELL, TASTE, ALLIED SENSES 



types of papillae, the fungiform, foliate, and vallate, very 

 generally carry taste-buds (Fig. 25). 



The fungiform papillae are relatively large knob-like 

 elevations scattered over the dorsum of the tongue. 

 They can be easily seen with the unaided eye and may 

 be readily located and identified. They commonly carry 



a few taste-buds embed- 

 ded in the epithelium of 

 their free outer sur- 

 faces. In sections of the 

 crowns of these papillae 

 parallel to the surface 

 of the tongue three or 

 four or more, rarely six 

 to eight, taste-buds may 

 be identified. In verti- 

 cal section it can be 

 seen that the taste-buds 

 are not indiscriminately 

 scattered over the free 

 surface of the papilla, 

 but are perched on the 

 secondary dermal pa- 

 pillae contained within the papilla proper and that they 

 always reach through the full thickness of the epidermis 

 from the dermal core of the secondary papilla to the free 

 outer surface of the primary papilla itself (Fig. 26). 

 This extension through the whole thickness of the epi- 

 dermis seems to be a common characteristic of taste- 

 buds, for it is to be noted in them from fishes to man. 

 It is an easy means of distinguishing them from other 

 bud-like receptors such as the lateral-line organs whose 



Fio. 25. Dorsal view of the human tongue 

 ehowing foliate papillw (f) and vallate papilla (v). 



