SENSE OP TASTE. 



865 



developed ; and its structure has been so carefully examined and described by 

 Messrs. Todd and Bowman, 1 that little remains to be added to their account 

 of it. The lingual papillae may be divided, in the first place, into the Simple 

 and the Compound; the former of which had previously escaped observation, 

 through not forming any apparent projection. The Simple papillae (Fig. 198) 



Fig. 198. 



Simple papillae near the base of the tongue : A. a, concealed tinder the epithelium ; b, uncovered by it. 

 Magnified 10 diameters. B. a. Arterial twig, supplying their capillary loops, v. Vein. The vessels are all 

 contained within the line b, b, of basement-membrane, c, c. Deeper epithelial particles resting on the base- 

 ment-membrane, d. Scaly epithelium on the surface. The granular interior of the papillae is represented at 

 e. c. Papillae in which the basement-membrane is not visible ; and the deep layer of epithelium seems to 

 rest on the capillary loop. Magnified 200 diameters. 



Fig. 199. 



Vertical section of one of the circumvallate papillae : a. 

 Central part, b, b. Border, c, c. Fissure between centre 

 and border. The secondary papillae are seen covered by 

 the epithelium. Similar papillae are seen, d, d, on the 

 membrane beyond. Magnified 8 diameters. 



are scattered in the intervals of the compound, over the general surface of the 

 tongue ; and they occupy much of the surface behind the circumvallate variety, 

 where no compound papillae exist. They are completely buried and concealed 

 beneath the continuous sheet of epithelium, and can only be detected when this 

 membrane has been removed by maceration ; they are then found to have the 

 general characters of the cutaneous papillae, but nerve-tubes have not yet been 

 detected in them. The Compound papillae are visible to the naked eye ; and 

 have been classified, according to their shape, into the circumvallate, the fungi- 

 form, and the filiform. The circumvallate or calyciform papillae (Fig. 199), 

 are eight or ten in number, and are situated in a Y-shaped line at the base of 

 the tongue. Each consists of a central flattened circular projection of the 

 mucous membrane, surrounded by a tumid ring of about the same elevation, 

 from which it is separated by a narrow circular fissure. The surface of both 

 centre and border is smooth, and invested by a scaly epithelium, which con- 

 ceals a multitude of simple papillae. The funyiform papillae (Figs. 201, 204, A) 

 are scattered singly over the tongue, chiefly upon its sides and tip. They pro- 



55- 



Physiological Anatomy and Physiology of Man," p. 380, Am. Ed. 



