THE SENSE OF TASTE. 



By J. B. Haycraft. 



Contents : — The Anatomical Mechanisms concerned in the Production of Taste, 

 and the Regions of Mucous Membrane which are involved, p. 1237 — Taste 

 Sensations, p. 1240— The Action of Drugs on Taste, p. 1241 — Modality and 

 Quality of Taste, p. 1242 — The Relationship between Taste Sensations and 

 the Chemico-Physical Properties of the Stimulus, p. 1244 — After-Tastes and 

 Successive and Simultaneous Contrast, p. 1244. 



Anatomical. — The anatomical mechanism concerned in the produc- 

 tion of the sensation of taste consists, in the first place, of certain 

 sensory end-organs within the cavity of the mouth and throat, and, in 

 the second place, of sensory nerves proceeding from these, and entering 

 the base of the brain, where they form connection with fibres from other 

 parts of that organ. The sensory surfaces in which the sensory nerves 

 of taste arise are as follows — the edges, upper surface, and root of the 

 tongue, the palate, the pillars of the fauces, the posterior surface of the 

 epiglottis, and the arytenoid cartilages of the larynx. 1 These sensory 

 surfaces are also connected with nerves that are concerned with the 

 production of the sensations of touch, temperature, and pain. 



The gustatory or taste bulbs found in the tongue and posterior sur- 

 face of the epiglottis are in all probability sensory end- organs ; they are 

 distributed as follows : — On the front of the tongue, where they are rare, 

 and lodged in the tops or sides of some of the fungiform papilla?, and at 

 the root of the tongue, where they are more numerous, and are lodged in 

 special gustatory papillae. 



In man there are some eight or ten of these gustatory or circum vallate 

 papilla? ; while in the rabbit the bulbs are lodged within foliated portions 

 of the mucous membrane, called the papilla? foliatse, placed one on each 

 side of the root of the tongue. They are found in a similar situation in 

 the human tongue, but not on special foliate papilla?. Gustatory bulbs 

 are also found upon the posterior surface of the epiglottis, and it was 

 this discovery that induced Nicholson to test the gustatory properties 

 of the epiglottis. 



Our belief that the bulbs are end-organs of taste, and not of common 

 sensibility, rests upon the following evidence. They are found solely 

 on the sensory surfaces of taste. Their highly specialised structure, 

 presenting many homologies with the end-organs of the special senses, 

 suggests their performance of some special function. We should on 

 this account expect them to be organs of taste, rather than organs of a 

 widely distributed sensory mechanism, like that of general sensibility, 

 which is elsewhere devoid of these structures. More direct evidence is 

 given by the effect of division of the glosso-pharyngeal nerve, which 

 1 P. Nicholson, Virchow's Archiv, Bd. cxxiii. S. 398-401. 



