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A TEXTBOOK OF PHYSIOLOGY 



the taste pore. Into this pore the hair-like processes of the true 

 gustatory cells project. These cells are delicate rod-like cells, with 

 a central nucleus surrounded by granular protoplasm. Around the 

 tapered base of the cell are the fine ramifications of the nerve of taste. 

 The taste cells are supported externally on either side by columnar 

 cells the sustentacular cells. These form no connection with the 

 gustatory nerve (Fig. 332). 



nv.fi. 



FIG. 332. TASTE BUD IK TONGUE OF MAN. (Redrawn after Hermann, from 

 Dahlgren and Kepner.) 



g. c., Gustatory or taste cells; sup. c., supporting cells; nv. /?., nerve fibrils. 



There are four sensation qualities of taste, sweet, salt, acid, and 

 bitter. They may be investigated by applying to the tongue test 

 solutions of various strengths at body temperature with a fine camel's- 

 hair brush, or by placing a measured volume of the solution on the 

 tongue. For exact localizing work, a form of instrument such as 

 shown in Fig. 333 may be used. It is usual to employ ether and 

 chloroform vapour with this instrument, since it has been found that 

 ether vapour blown on the tongue produces the sensation of bitterness, 

 and chloroform vapour a sensation of sweetness. 



FIG. 333. APPARATUS FOR TESTING TASTE SENSATIONS. 

 A, Z, two-way tap; E, insufflating bulb; C, D, odour chambers; 1, 2, clips. 



The nature of the stimulus for taste is chemical. It is necessary 

 for a body to be in solution for the sensation to be evoked. A dry 



