766 



SPECIAL SENSES. 



organs of taste. They are found on the lateral slopes of the circumvallate papilla and 

 occasionally on the fungiform papill. The structure of these organs is very simple. 

 They consist of flask-like collections of spindle-shaped cells, which are received into little 

 excavations in the epithelial covering of the mucous membrane, the bottom resting upon 

 the connective-tissue layer. Their form is ovoid, and, at the neck of the flask, is a 



FIG. 237. FIG. 238. 



Varieties of papillae of the tongue. (Sappey.) 



Fig. 237. Medium-sized circumvallate papilla: 1, papilla, the base only being apparent: it is seen that the base is 

 covered with secondary papillae ; 2, groove between the papilla and the surrounding wall ; 3, 3, wall of the papilla. 

 Fig. 2-38. Fungiform, filiform, and hemispherical papilla? : 1, 1, two fungiform papillae, covered with secondary pa- 

 pillae; 2, 2, 2, filiform papilla? ; 8, a filiform papilla, the prolongations of which are turned outward; 4. a filiform 

 papilla, with vertical prolongations ; 5, 5, small filiform papillae, with the prolongations turned inward ; 6, 6, fili- 

 form papilla?, with striations at their bases ; 7, 7, hemispherical papilla?, slightly apparent, situated between the 

 fungiform and the filiform papillae. 



rounded opening, called the taste-pore. Their length is from -g-^ to -5^-5-, and their trans- 

 verse diameter, about -$-$ of an inch. The cavity of the taste-beakers is filled with cells, 

 of which two kinds are described. The first variety, the outer cells, or the cover-cells, 

 are spindle-shaped, and curved to correspond to the wall of the beaker. These come to 

 a point at the taste-pore. In the interior of the beaker, are elongated cells, with large, 

 clear nuclei, which are called taste-cells. It is supposed that nerve-fibrils are connected 



directly with these cells. As far as we 



can learn, the only reason why these 

 structures are connected with the physi- 

 ology of gustation is on account of their 

 anatomical relations to the gustatory 

 papillas. 



It now remains only to note the ulti- 

 mate distribution of the nerves in the- 

 gustatory organ. Upon this point, ana- 

 tomical researches are not entirely sat- 

 isfactory. However, the following de- 

 scription, by Elin, may be regarded as 

 probably correct, although the facts 

 have not been absolutely demonstrated. 

 According to this authority, from the submucous tissue, small nerve-branches pass per- 

 pendicularly to the upper layer of the membrane. These fibres have a varicose appear- 

 ance. In the most superficial layer of the mucous membrane, there is a net-work of fine, 

 non-medullated fibres ; and, from this net- work, branches follow the blood-vessels into the 

 papillss and penetrate the epithelium. Sometimes, though more seldom, they pass into 

 the epithelium lying between the papilla. In this layer, there are branches which end, 

 some in nerve-cells, and some taking a winding course and passing into neighboring 



FIG. 239. Taste-buds from the lateral taste-organ of the 

 rabbit. (Engelmann.) 



