XXI ] TASTE-BUDS. 249 



TASTE-BUDS. 



6. Taste-Buds, or the peripheral organs of taste, occur on the 

 fungiform papilla) and lateral surface of the circumvallate, soft 

 palate, posterior surface of the epiglottis, and a few amongst the 

 epithelial cells on the dorsum and sides of the tongue. It is more 

 convenient, however, to study them in the rabbit. On either side 

 of the posterior part of the rabbit's tongue are two oval patches 

 with transverse ridges and intervening furrows, the papillse foliatae 



(fig- 239). 



(i.) Cut out these parts and harden them for fourteen days or 

 so in Miiller's fluid and then in spirit. Stain in bulk in borax- 

 carmine or haematoxylin and cut in paraffin. 



(ri.) The excised organ, with as little adherent muscle as possible, 

 is placed for one hour in i per cent, osmic acid, or pinned on a 

 cork and exposed for the same time to the vapour 

 of osmic acid. Fine sections are made across the 

 laminae, and stained with logwood and mounted in 

 balsam. 



(a.) (L) Observe the sections of the laminae, each 

 one with a central papilla or projection of connective 

 tissue (fig. 240, /). This is covered by many layers 

 of stratified epithelium. 



(b.) Between the laminae a furrow, and embedded 

 in the epithelium, on each side of this furrow, the 

 taste-buds (#), which are oval in shape, and composed 

 of epithelial cells, whose bases touch the connective 

 tissue of the mucous membrane, where they receive FIG. 

 a branch of the glosso-pharyngeal nerve. The apex 

 has an open mouth gustatory pore which com- 

 municates with the furrow. The cells composing the bud are 

 arranged somewhat like the staves in a barrel. 



(<?.) Gland-ducts open at the bases of the furrows, and if these 

 ducts be not seen, sections of their acini serous gland are sure 

 to be seen deep in the corium (fig. 240, d). The corium has what 

 look like secondary papillae on it, but they are really septa (I'}. 



(<L) (H) Study a single taste-bud (80 ^ long and 40 //, broad) 

 It is composed of two kinds of elongated epithelial cells. 



(i.) The sustentacular cells, which are most numerous. They 

 are elongated, flattened, and either of uniform breadth or narrowed 

 at their base. They form a protective covering for the true gusta- 

 tory cells, which lie between and within them. 

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