590 



THE DIGESTIVE TRACT. 



filiform papillae of the lateral border. Terminal nerve-bulbs 

 have been -found at the bases of these papillae. (See Figs. 248 

 and 249.) 



(1)) The fungiform papillcv are semi-globular or oblong forma- 

 tions scattered between the filiform papillae (usually not exceed- 

 ing one mm. in breadth and height), and arising from the level of 

 the mucosa with a slightly narrowed neck. Toward their cir- 

 cumference the connective tissue produces a number of smaller 

 so-called secondary papillae, which are not marked on the outer 

 surface of the thin epithelial investment. Sometimes the body of 

 the papilla is cylindrical, without a neck, and the epithelium may 

 assume features resembling those of the filiform papillae, though 



FIG. 248. FILIFORM PAPILLAE OF 

 THE TONGUE OF MAN. 



E, layer of horny epitlielia; C, connect- 

 ive tissue with injected blood-vessels ; L, 

 lymphatic (adenoid) layer; M, striped mus- 

 cles. Magnified 150 diameters. 



FIG. 249. FUNGIFORM PAPIL- 

 LA OF THE TONGUE OF MAN. 



E, epithelial layer; C, connective 

 tissue with injected blood-vessels ; L, 

 lymphatic (adenoid) layer ; M, striped 

 muscles. Magnified 150 diameters. 



the prolongations are never numerous, and usually short and 

 broad. Such papillae are described as conical. Terminal nerve- 

 bulbs are found at the bases of the secondary papillae. 



(c) The circwmvallate papillae, situated at the posterior part of 

 the upper surface of the tongue, represent cylindrical elevations 

 (1-2 mm. in height and 1-3 mm. in width), which are surrounded 

 by a wall of the mucosa, and separated from this wall by a fur- 



