PRACTICAL HISTOLOGY. 



[xxi 



LESSON XXL 

 TONGUE TASTE-BUDS SOFT PALATE. 



TONGUE. 



PLACE small portions in Miiller's fluid or 2 per cent, potassic 

 bichromate for fourteen days, and complete the hardening in 

 alcohol, or harden it in mercuric chloride. Make vertical trans- 

 verse sections. It is well to have the tongue of a small cat or 

 kitten, and parts of the human tongue also the former because a 

 complete transverse section can be put on a slide. The structure 

 will vary according as the section is made through the anterior or 

 posterior part of the organ, as the latter contains many lymph 

 follicles and mucous glands. The sections may be stained in 

 logwood and mounted in balsam. 



1. T.S. Tongue of Cat. (a.) (|_) Observe the papillae, of various 

 shapes, on the dorsum of the tongue, and covered by stratified epi- 

 thelium. Under this the 

 connective tissue of the 

 mucous membrane (fig. 



234). 

 (b.) Muscular Fibres. 



Many cut transversely and 

 arranged in groups under 

 the dorsal mucous mem- 

 brane and elsewhere ; others 

 which run from the vertical 

 mesial plane or septum hori- 

 zontally outwards, and some 

 which pass vertically. The 

 last may be seen to become 



conical and end in the connective tissue of the mucous membrane. 



Some of these fibres branch. (The methods of isolating branched 



fibres are referred to in Lesson XVI. 3.) 



(r,.) Lingual Papillae. The dorsum of the tongue is beset with 



elevations- of the mucous membrane covered by stratified epithelium, 



and constituting three varieties of papillae. 



(i.) Filiform (.7-3 mm long), by far the most numerous, and are 



placed all over the dorsum. They are conical elevations of the 



mucous membrane, the upper end of which is beset with five, fifteen, 



FIG. 234. T.S. ot One-halt of the Tongue of a Cat. 



