122 NORMAL HISTOLOGY. 



brana propria. The elevations of the stroraa of the mucosa give rise 

 to the papillae. These are of three forms, filiform, or narrow ; fungi- 

 form, or club-shaped; and circumvallate, or broad and flat. The 

 circumvallate papilla are confined to the posterior part of the dor- 

 sum. The fungiform varieties occur upon the dorsum. Often sec- 

 ondary papilla? are present. 



Glands occur in the stroma and are of the mucous and serous 

 types. The mucous glands are of the compound tubular variety, 

 and occur at the base and edges of the tongue. The serous glands 

 are of the saccular form, and occur near the circumvallate papillae 

 and taste-buds. 



The muscular tissue of the tongue consists of striated muscle 

 fibres arranged in bundles which run vertically, transversally, and 

 longitudinally. The spaces between the bundles are filled up with 

 connective tissue, fat-cells, and glands. There is a connective tis- 

 sue partition, called the septum lingualce, which passes vertically 

 through the middle of the tongue, dividing the muscular tissue into 

 two portions. 



The adenoid tissue at the base of the tongue is found in the 

 crypts, or depressions, of the mucosa, and consists of a connective 

 tissue reticulum and lymphoid ceils. The tongue is richly supplied 

 with blood-vessels, lymphatics, and nerves. 



Laboratory exercise No. 38. The tongue. Harden with alcohol, em- 

 bed in paraffin, and stain with carmine, method No. 3. Study first the 

 mucosa, demonstrating the epithelial layer, basement membrane, tunica 

 propria, and the filiform, fungiform, and circumvallate papillae. Make 

 a search for taste buds. Observe the loose fibrous structure of the 

 tunica propria and demonstrate, if possible, mucous and serous glands. 

 Notice the disposition of the bundles of striated fibres. Focus upon a 

 fibre with H. P. and demonstrate its striations. In the inter-fascicular 

 spaces observe connective tissue and fat-cells. A section prepared from 

 the base of the tongue should exhibit adenoid tissue in the crypts of the 

 mucosa. Does your section show the septum lingualae? Drawings. 



II. THE TEETH. 



The teeth are derived from the epiderm and mesoderm. The most 

 important structure of the tooth is the pericementum, or peridental 

 membrane, for upon its healthy action the condition and usefulness 



