LINGUAL PAPILLA AND GLANDS. 



809 



nerve filaments in the human tongue. It is still a matter of doubt whether 

 they enter the secondary papillae surmounting the filiform set, the density of 

 the tissue rendering the investigation peculiarly difficult in these. In 

 the frog's tongue, Billroth and Axel Key believe that they have traced con- 

 tinuity of nerve- filaments with structures in the epithelium ; and, according 

 to Axel Key, the arrangement is very similar to that of the olfactory cells 

 viz., rodHke bodies placed between the epithelial cells and continuous by 

 their deep extremities with varicose fibres. (Billroth in Muller's Archiv, 

 1858, p. 159 ; Axel Key in Reichert's Archiv, 1861, p. 329). 



Glands. The mucous mem- 

 brane of the tongue is provided 

 with numerous follicles and 

 glands. The follicles, simple and 

 compound, are scattered over the 

 surface ; but the rounded con- 

 glomerate glands, called lingual 

 glands, are collected about the 

 posterior part of the dorsum of 



Fig. 567. RACEMOSE Mucous GLAND, 



FROM THE FLOOR OF THE MoDTH 



(from Kolliker). 



A, the entire gland as seen in sec- 

 tion ; 4p a, covering of connective 

 tissue ; 6, excretory duct; c, glandular 

 vesicles ; d, duct of one of the lo- 

 bules. 



B, diagram of one of the lobules, 

 more highly magnified; a, excretory 

 duct of the lobule ; b, secondary 

 branch ; c, the glandular vesicles as 

 they lie together in the gland ; d, the 

 same separated, showing their con- 

 nection as a glandular tube. 



the tongue, near the B 



papillae vallatse and 

 foramen csecum, into 

 which last the ducts 

 of several of these 

 glands open, Other 

 small glands are 

 found also beneath 

 the mucous mem- 

 brane of the borders 

 of the tongue. 



There is, in particular, a small group of these glands on the under surface 

 of the tongue near the apex. They are there aggregated into a small oblong 

 mass, out of which several ducts proceed and open separately on the mucous 

 membrane. (Blandin, in Archives gen. de Me'decine, 1823 ; Nuhn, Ueber 

 eilie noch nicht naher beschriebene Zungendriise, Mannheim, 1845.) 



B. MUSCULAR SUBSTANCE. The substance of the tongue is chiefly com- 

 posed of muscular fibres, running in different but determinate directions ; 

 hence the variety and regularity of its movements, and its numerous changes 

 of form. Many of the contractile fibres of the tongue belong to muscles 



