276 



DIGESTIVE ORGANS. 



[sect. 131. 



at the end splits up into a number of long and slender (cr 01'" to 

 0*02'"), sometimes sub-divided processes, with cornified cells, giving 

 to the whole the appearance of a fine brush, and measuring up to 

 0*5'", o - 6"', 07'" in length, and 0-02'" to 0'028'" in breadth at 

 their bases. In each papilla, a small artery ramifies, and in 

 such a manner, that each simple secondary papilla contains a 

 capillary loop, from which a small venous vessel returns. The 

 nerves, which are not always readily found, present one or two 

 small trunks with from 5 to 10 dark-bordered primitive fibres of 

 o - oo2'" to 0003'", which are withdrawn from view at the base of 

 the simple papillae, and terminate in a manner not as yet exactly 

 ascertained. 



The papilla fungiformes are formed of a club-shaped process of 

 the mucous membrane, which is thickly beset on its whole surface 

 with simple conical papillae of O'l'" to 012'" in length, and covered 

 by a simple epithelium, like that which occurs elsewhere in the 

 oral cavity, and icithout cornified cells and filiform processes, which 

 when measured from the apices of the papillae, possesses a thick- 

 ness of o - 04'" to o'05"\ The papilla contains much less elastic 

 tissue than the papillce. filiformes, and the simple secondary 

 papillae contain scarcely any ; but on the other hand, there is a 

 very distinct mesh-work of connective tissue in bundles, 0*002'" to 

 - 003"' in diameter. The vessels present the same characters as in 

 the filiformes, only they are much more numerous ; and with re- 

 gard to the nerves, one or two thicker trunks, 0*04/" to o - o8"', and 

 several thinner filaments pass into each fungiform papilla, in which, 

 branching in form of tufts and variously anastomosing, they finally 

 separate from each other, and pass in all directions towards the 

 simple secondary papillae and their touch-bodies. The terminations 

 of these nerves at the base of the simple papillae measure only 

 0001'" to 000 1 5", and they appear to end by means of free pale 



processes. 



Fig. 114. 



Papilla circumvallata of man in section. A. Proper papilla ; 

 B. wall ; a. epithelium ; b. secondary papilla? ; bb. nerves of the 

 papiU» and the wall. Magnified about 10 times. 



In the papillce cir- 

 cumvallata (fig. 1 2 1 ) , 

 the papilla, which 

 might be regarded as 

 a fungiform papilla 

 pressed flat, is closely 

 beset on its flat ter- 

 minal surface with 

 simple conical second- 

 ary papillae, and co- 



