668 



SPECIAL SENSES. 



gustatory membrane, so extensively, indeed, that it is difficult to exactly locate 

 the seat of the special impression. In this way, by the movements of the 

 tongue, aided by an increased flow of saliva, the actual contact of the savory 

 articles is rapidly effected. The thorough distribution of these substances 

 over the tongue and the mucous membrane of the general buccal cavity leads 

 to some confusion in the appreciation of the special impressions; and in 

 order to ascertain if different portions of the membrane possess different 

 properties, it is necessary to make careful experiments, limiting the points 

 of contact as exactly as possible. This has been done, with the result of 

 showing that the true gustatory organ is quite restricted in its extent. 



Physiological Anatomy of the Organ of Taste. Anatomical and physio- 

 logical researches 

 have shown that, 

 at least in the hu- 

 man subject, the 

 organ of taste 

 probably is con- 

 fined to the dorsal 

 surface of the 

 tongue and the 

 lateral portion of 

 the soft palate. 

 The upper surface 

 of the tongue pre- 

 sents a large num- 

 ber of special pa- 

 pillae, called, in 

 contradistinction 

 to the filiform pa- 

 pillae, fungiform 

 and circumval- 

 late. These are 

 not found on its 

 under surface or 

 anywhere except 

 on the superior 

 portion ; and it is 

 now well estab- 

 lished that the 

 circumvallate and 

 fungiform papillae 

 alone contain the 



FIG. 238. Papillae of the tongue (Sappey). 

 1, 1, circumvallate papillae ; 2, median circumvallate papilla, which entirely 



fills the foramen caecum ; 3, 3, 3, 3, 



pillae ; 5, 5, vertical folds and furrow 



6, glands at the base of the tongue ; 7, 7, tonsils ; 8, epiglottis ; 



glosso-epiglottidean fold. 



foramen caecum ; 3, 3, 3, 3, fungiform papillae ; 4, 4, filiform pa- ..,, .,_ _.c 

 pillae ; 5, 5, vertical folds and furrows of the border of the tongue ; 6, 6, 6, 01 g ans o:t 



" 



median Experiments up- 

 on the gustatory 

 organs, by the application of solutions to different parts through fine, glass 



