CHAP. XV.] COMPOUND PAPILLA OF THE TONGUE. 



437 



Similar papillae near the base of the tongue : A. a. concealed under 

 the epithelium ; b. uncovered by it. Magnified 10 diameters. B. a. 

 Arterial twig, supplying their capillary loops, v. Vein. The vessels 

 are all contained within the line b, b, of basement membrane, c, c. 

 Deeper epithelial particles resting on the basement membrane, d. 

 Scaly epithelium on the surface. The granular interior of the papillae 

 is represented at e. c. Papillae in which the basement membrane is 

 not visible ; and the deep layer of epithelium seems to rest on the 

 capillary loop. Magnified 200 diam. 



Fig. 96. 



The circumvallate pa- 

 pilla (fig. 94, a, and 

 fig. 96) consist of a 

 central flattened pro- 

 jection of the mucous 

 membrane of a cir- 

 cular figure, and from 



~2Q to iV f an i ncn 

 wide, surrounded by 

 a tumid ring of about 

 the same elevation, 

 but less diameter, from 

 which it is separated 

 by a narrow circular 

 fissure, with, it is said, 

 a few mucous ducts 

 opening at the bot- 

 tom. In the smaller 

 examples this fissure 

 exists only on one side. The sur- 

 face of both centre and border is 

 smooth, and invested by scaly epi- 

 thelium, concealing a multitude of 

 simple papillae, in all respects 

 similar to those just described. 

 About the point where the two 



-.. f, . n , -n Vertical section of one ofthecircumvallate papilla;: 



lines Of CirCUmvallate papillae meet, a. Central part. &,&. Border. c,c. Fissure between 

 .-I -11 ..-i ,1 r> centre and border. The secondary papillae are seen 



tnere IS USUally One Wltll the IIS- covered by the epithelium. Similar papillae are seen, 

 i j j -i d.d.on the membrane beyond. Magn. 8 diam. 



sure so large and deep as to have ' 



received the name of foramen cacum. The central part is frequently 

 small, or elongated and thrown on one side of the foramen. In the 

 specimen next represented (fig. 97), this is shewn covered with se- 

 condary papillae, having all the characters of those above mentioned. 

 In its interior we failed to detect any nerves provided with white 

 substance. In this region of the tongue fissures and papillae of 

 irregular size and shape are often met with, and mucous glands 

 are disseminated beneath the surface. 



The fungiform papillae (fig. 94, b, and fig. 98) are scattered singly 

 among the filiform papillae, chiefly on the sides and tip of the tongue, 

 and very sparingly in the middle of the dorsal region. They are 

 usually narrower at their base than summit, where they are from 

 sV * ^V f an i ncn i n diameter. Like those last described, they 



