438 



JNNEKVATION. 

 Fig. 97. 



[CHAP. xv. 



A. Compound papilla on the side of the foramen caecum, injected : a, a. Arterial twigs. v,v. 

 Veins. The capillary loops indicate the simple papillae ; in one of which, b the injected matter has 

 been extravasated within the basement membrane of the papilla, the outline of which is thus dis- 

 tinguished, c. Capillary plexus, where no papillae exist, e, e. External surface of the epithelium 

 of the papilla. Magn. 15 diam. 



B. One of the simple papilla? of A. : a. v, v, Arterial and venous sides of the capillary loops. b,b. 

 Basement membrane, d. Deeper epithelial particles resting on the basement membrane. *. Scaly 

 epithelium on the surface. -Magn. 300 diameters. 



Fig. 98. 



A. Fuiigiform papilla, shewing the secondary papillae on its surface, and at a its epithelium cover- 

 ing them over. Magnified 35 diameters. 



B. Another, with the capillary loops of its simple papillae injected, a. Artery, v. Vein. The 

 groove around the base of some of the fungiform papillae is here represented, as well as the capil- 

 lary loops, c, c, of some neighbouring simple papillae. Magnified 18 diameters. 



are clotlied with simple papillae ; and their investing epithelium is so 

 thin, that the blood, seen through it, gives them a red colour, usually 

 sufficient to distinguish them from the filiform ones among which they 

 lie. They contain nerve-tubes, having a loop-like arrangement. 



The compound papillae of the third variety (fig. 94, d, and figs. 99 

 and 100) are of the average length of ^ of an inch, and, as their 

 name implies, are more or less conical or filiform in shape. They 

 are distinguished moreover by their whitish tint, derived from the 



