THE TONGUE. 19 



portions several nervous trunks of 005 — 008"' in diameter, 

 which, as they ascend, subdivide into a very elegant plexus, from 

 which the nerves of the secondary papillae radiate upon all sides. 

 In other respects, they resemble the p. fungiformes, except that 

 the nerve-tubules, even in the trunks, have not a greater 

 average diameter than , 002 /// , and the largest not more than 

 O'OOS'", while at the base of the secondary papillae it is not 

 more than 0*001 — 0*001 5'". The walls of these papillae also 

 contain many nerves, whose ultimate disposition appears to be 

 exactly the same as in the papillae themselves. 



[The lingual papillae present many varieties, the following 

 of which are the most important : 1. The papilla filif or mes are 

 all elongated, and provided with very considerable epithelial 

 processes. The appearance of what is commonly called a 

 gastric furred tongue, depends principally upon a growth of the 

 epithelial processes of the papilla filiformes, which, all directed 

 backwards and in close apposition, form apparently a peculiar 

 white coating. If the processes become longer, so that the 

 papilla filiformes measure \%" — 2"', we have the lingua hirsuta 

 or villosa, which is not uncommon in various disorders ; and at 

 length forms may be produced, in which the tongue looks as if 

 it were covered with hairs 4 — 6'" long. 2. The papilla fili- 

 formes possess very small epithelial processes, or none at all, 

 and are hardly distinguishable from the smaller p. fungiformes. 

 3. The papilla filiformes do not exist as special elevations, but are 

 imbedded in a general epithelial investment of the dorsum of the 

 tongue. Tongues may be observed, particularly in old people, 

 which, without being furred, in some spots or over a large 

 extent, present no papillae at all, but have either a perfectly 

 smooth surface, or exhibit only a few linear elevations," corre- 

 sponding with the rows of papillae which would, otherwise, exist 

 there. In these places we find the epithelium more deve- 

 loped, and beneath it small papillae, more of the ordinary form. 

 Tongues which, with better developed papillae, present a smooth 

 surface, are again different from these; here the smooth or 

 cracked surface is produced by the papillae being glued together 

 by superabundant epithelium, mucus, blood, pus-corpuscles, and 

 mucedinous or yeast-like fungi. 4. The epithelial processes of the 

 filiform papilla are covered with mucedinous fungi. Every micro- 



