THE SENSE OF TASTE. 



739 



The taste-cells are narrow and slightly thickened in the middle, where 

 the nucleus is situated. The taste-bulbs occur chiefly on the sides of 

 the circumvallate papilla, although a small number of them are on 

 the fungiform and the soft palate. The ends of the taste-bulbs near 

 the surface have a minute, funnel-like opening called the taste-pore. 

 The number of taste-bodies is very great. If the glosso-pharyngeal 

 nerve is cut, the taste-bodies degenerate. 



The proper stimuli for the end-bulbs of the gustatory nerves are 

 rhe savory substances. These must be dissolved in the liquids of the 

 louth before they can penetrate the outer cells of the mucous mem- 

 >rane to come into contact with the nerve-filaments in the imbedded 



Fig. 301. Structure of the Taste-organs. (LANDOIS.) 



I. Transverse section of a circumvallate papilla. W, the papilla, v, v, The 

 wall in sections. R, R, The circular slit, or fossa. K, K, The taste-bulbs in 

 position. N, N, The nerves. 



II. Isolated taste-bulbs. D, Supporting, or protective, cells. K, Lower 

 end. E, Free end, open with the projecting apices of the taste-cells. 



III. Isolated protective cell (d) with a taste-cell (e). 



uilbs. The most suitable temperature for the thorough testing of 

 liquids is 100 F. 



The intensity of the gustatory impression depends upon various 

 [actors : the nature of the substance, the duration of the impression, 



msibility of the region touched, and the stimulating action of the 



ibstance upon the mucous membrane. The flavor of a substance 

 Iocs not depend upon its chemical properties, for both quinine and 



ilphate of magnesia are bitter; sugar, chloroform, and glycerin are 



reet. 



Improper stimuli give gustatory impressions. Thus, the galvanic 



irrent applied to the tongue gives an acid taste at the positive pole 



id a weaker, alkaline taste at the negative pole. 



