766 



SPECIAL SENSES. 



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

 occasionally on the fungiform papillse. 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. FKJ. 238. 



Varieties ofpapillce, 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. 238. Fungiform, filiform, and hemispherical papillae : 1,1, two fungiform papillae, covered with secondary pa- 

 pillae; 2,2, 2, filiform papillae; 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 papillae, with striations at their bases ; 7, 7, hemispherical papillae, slightly apparent, situated between the 

 fungiform and the filiform papillae. 



rounded opening, called the taste-pore. Their length is from ^ 7 to -g^-, 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 

 papillae. 



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 



l 



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

 rabbit. (Engelmann.) 



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 

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

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

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



