TASTE. 811 



terminate in flask-shaped organs which are termed the gustatory bulbs or 

 taste buds. (Fig. 203.) These bulbs are found principally in the papillary 

 surface of the wall of the circumvallate papillae. They are also found in 

 the fungiform papillae, but are less numerous. They consist of a flask-shaped 

 fundus, which rests upon the subepithelial tissue, and a mouth which opens 

 upon the surface of the mucous membrane. The mouth is known as the 

 gustatory pore. The fundus of the flask is composed of two varieties of cells ; 

 the outer or investing cells are fusiform, nucleated, and granular, placed 

 parallel and arranged concentrically in a direction from the base to the 

 neck ; they thus form a wall which encloses elongated nucleated cells with 

 filamentous processes, which extend through the gustatory pore and project 

 as very finely pointed or truncated extremities. These inner cells are called 

 the gustatory cells, and are supposed to be the essential terminal elements 

 concerned in gustation. Their relation to the gustatory nerves has not as 

 yet been clearly demonstrated, but they are evidently connected with the 

 ganglionic plexuses of nerve-fibres at the papillary bases. The gustatory 

 nerves are also supposed to terminate in the epithelium of the papillae.] 



733. The word taste is frequently used when the word smell ought to 

 be employed. We speak of " tasting " odoriferous substances, such as an 

 onion, wines, etc., when in reality we only smell them as we hold them in our 

 mouth ; this is proved by the fact that the so-called taste of these things 

 is lost when the nose is held, or the nasal membrane rendered inert by 

 a catarrh. 



The terminal organs of the sense of taste thus more strictly defined are 

 the endings of the glosso-pharyngeal and lingual nerves in the mucous mem- 

 brane of the tongue and palate, those nerves serving as the special nerves 

 of taste. Whether the so-called gustatory buds can be regarded as specific 

 organs of taste appears doubtful. The subsidiary apparatus is confined to 

 the tongue and lips, which by their movements assist in bringing the sapid 

 substances into contact with the mucous membrane of the mouth. 



Though we can hardly be said to project our sensation of taste into the 

 external world, we assign to it no subjective localization. When we place 

 quinine in our mouth, the resulting sensation of taste gives us no informa- 

 tion as to where the quinine is, though we may learn that by concomitant 

 general sensations arising in the buccal mucous membrane. 



734. We recognize a multitude of distinct tastes, which may be broadly 

 classified into acid, saline, bitter, and sweet tastes. Sapid substances have 

 the power of producing these sensations by virtue of their chemical nature. 

 But other stimuli will also give rise to sensations of taste. When the tongue 

 is tapped, a taste is felt ; and when a constant current is passed through the 

 mouth, an alkaline or, in some persons, a bitter metallic taste is developed 

 when the anode, and an acid taste when the kathode, is placed on the tongue. 

 It is probable that in these cases the terminal organs are indirectly affected 

 by the current. When hot or pungent substances are introduced into the 

 mouth, sensations of general feeling are excited, which obscure any strictly 

 gustatory sensations which may be present at the same time. 



Though analogy would lead us to suppose that a stimulus applied to any 

 part of the course of the real gustatory fibres of either the glosso-pharyngeal 

 or lingual nerves would give rise to a sensation of taste and nothing else, the 

 proof is not forthcoming, since both these nerves are mixed nerves contain- 

 ing other afferent fibres as well as those of taste. 



When the constant current is used as a means of exciting taste, gustatory 

 sensations are found to be developed in the back, edges, and tip of the 

 tongue, the soft palate, the anterior pillar of the fauces, and a small tract 

 of the posterior part of the hard palate. They are absent from the anterior 



