ORGAN OF TASTE IN MAMMALIA, 201 



a net, the meshes of which in successive layers become canals 

 through which the fibres of the third set pass ; hence in whatever 

 plane they be viewed, two sets are seen, in profile, crossing, and 

 one, in section, perforating ; by which arrangement they mutually 

 support and conduct each other, independently of connective tissue, 

 the dispensing with which allows for the aggregation of so much 

 more muscular tissue in the tongue's substance. In fig. 147, a 

 magnified view is given of a section from the upper surface, a, in 

 fio-. 145 : a are the vertical fibres extending to that surface, be- 



O O J 



yond the uppermost transverse fibres, b, and decussating with the 

 longitudinal fibres shown in section at c. This complex arrange- 

 ment becomes simplified toward the apex : the longitudinal fibres 

 first ceasing, next the vertical ones, and the transverse alone 

 being continued to the tip. 1 



The skin of the tongue is divided into the papillose, glandular, 

 and smooth, mucous, or faucial areas : the latter, fig. 141, d, has 

 about half an inch of longitudinal extent when not stretched, 

 and answers to the much more considerable tract in the Lion. 

 The glandular area is defined anteriorly by the fossulate papilla, 

 ib. /, here arranged ( en chevron,' four on each side converging 

 toward the backwardly turned point : behind this is sometimes 

 seen a fossa devoid of papilla, the ( foramen caecum ' of Anthropo- 

 tomy. The papillose area extends over the major part of the 

 tongue to its tip and down the sides along part of the under 

 surface ; it is roughened by papillae which extend from the 

 medial groove in oblique series forward and outward, repeating 

 in the main the arrangement of the fossulate or glandular 



o o 



papillae. 



The tongue-skin presents a basal areolar tissue, so dense in 

 the glandular and papillose area? as to resemble the corium : at 

 the faucial area and under surface of the tongue it softens into 

 the character of that of the mucous membrane of the cavity 

 with which it is continuous : where it overlies the muscular part 

 of the tongue, as in fig. 145, a, it is closely adherent thereto, 

 and is thickest at the middle line : peripherally it projects as 

 ' papillae,' sinks into ' fossulaa,' and is inverted to form the ducts 

 or orifices of mucous follicles. The epithelium is scaly, thick 

 and distinguishable into a deep layer adherent to the corium and 

 a superficial layer which readily desquamates. The so-called 

 1 papillae ' are processes of the corium, rather analogous to the 



1 For further and more minute details of this exquisite arrangement of the mus- 

 cular tissue for the functions of the tongue, reference should be made to the admirable 

 article CCXL, in which the accomplished author, HYDE SALTER, first described it. 



