ORGANS OF THE BODY. 



611 



Fisr. 570. From the lateral gustatory organ of the rabbit. 

 The gustatory ridges are represented in vertical transverse 

 section (.after Engelmann). 



are several millimetres across, and present five longitudinal clefts, which 

 contain numerous gustatory buds (Krause). 



The crown and side walls of the circumvallate papillae, with the 

 internal surface of the surrounding ridge of mucous membrane, are 

 clothed with a thin layer of the ordinary flattened epithelium of the 

 tongue. Now it is principally the side walls of the papillae (fig. 570), but 

 not unfrequently the inner 

 aspect likewise of the en- 

 circling ridge (the crown of 

 the papillae never), which 

 presents the terminal struc- 

 tures just mentioned. These 

 are pear-shaped or bud-like 

 organs which traverse the 

 whole thickness of the epi- 

 thelial covering, and present, 

 according to the animal examined, a plump, or slender figure. Their 

 number is, as a rule, considerable. In length they attain in the tongue 

 of the ox, 0-1717; in man, 0'0810-0'0769 ; in the deer, hare, and dog, 

 0*0729 mm.; in the rabbit, 0-0575 mm. 



Their walls consist of flattened lanceolate cells (fig. 571, 2 a) arranged 

 side by side like the staves of a cask, or the sepals of a flower bud. 

 Above these supporting or encasing cells 

 converge ; below they are narrowed into 

 ribband-like processes, which sink into the 

 tissue of the mucosa, and are to all appear- 

 ance connected with the elements of the 

 same. 



The apices of the gustatory buds (1) 

 perforate the epithelial covering, and lie 

 naked and free. Here we may observe 

 small round holes arranged with consider- 

 able regularity, and formed by the borders 

 of either several, or perhaps two, or even 

 of one single cuticular cell. Through 

 these openings delicate terminal filaments 

 may project (Sckwalbe). 



A second species of cell (2 I) is now 

 found in the interior of the gustatory bud, 

 enclosed within the cortical lamina of 

 encasing cells. These elements appear in 

 the form of longitudinal bundles, and are 

 known as " gustatory cells" A fusiform 

 nucleated body becomes narrowed above 

 into a thin rod or spike, and is fined off 

 below into a thread-like process. The 

 ends of such rods project at times to a 

 greater or less extent from the openings 

 of the gustatory buds, while the end filaments below, on which varicosities 

 may be observed, penetrate into the tissue of the mucous membrane. 



Underneath the gustatory buds the latter is seen to contain a plexus 

 of pale and medullated nerve fibres. Immediately under the epithelial 

 covering pale single or dividing terminal filaments present themselves. 



Fig. 571. 1. Gustatory bud from the 

 rabbiD. 2 a, encasing cells; 2 b, rod- 

 cells; 2 c, a rod-cell with fine terminal 

 thread. 



