in THE SENSE OF TASTE 141 



body temperature. Tactile sensibility can be excluded by apply- 

 ing the substance in solution not as a solid or powder, so as to 

 avoid any mechanical stimulation of the touch spots. To 

 distinguish the sensations excited through the pain organs from 

 taste, it is necessary to compare the effect of the solutions on 

 those parts of the oral cavity that have and have not taste-buds 

 the latter being the interior surface of the tongue, mucous 

 membrane, of the gums, cheeks, hard palate, and centre of the 

 tongue. By this means it is found that the attributes sharp, 

 astringent, oily, dry, etc., as applied to tastes, are due exclusively 

 to the general sensibility of the oral mucous membrane, particu- 

 larly that of the tongue. All these sensory attributes are in i'act 

 produced when the test solutions are applied to the mucous sur- 

 faces that are destitute of taste-buds, but no pure gustatory sensa- 

 tions (sweet, sour, bitter, salt) are thus excited. 



Zenneck (1839) only admitted two qualities of purely gustatory 

 sensation, sweet and bitter. Valentin (1848) maintained the 

 same. More recently (1883), M. Duval went even further, and 

 asserted that taste sensibility was intermediate between common 

 sensibility and specific sensibility, and that many sensations 

 aroused on the tongue might equally be evoked from other mucous 

 membranes and on certain parts of the skin. 



On the other hand, the careful observations of Stich (1857) 

 showed that the acid taste is not diffused over the whole of the 

 buccal mucosa, but only when there are taste papillae. Schiff 

 (1867), again, found that where the epidermis had been removed 

 by a blister, the application of solution of sugar, quinine sulphate, 

 or citric acid gave rise to different sensations which bore no 

 resemblance to taste. He also found that any highly diluted acid 

 which produced no sensation on the non- gustatory mucous 

 membrane of the mouth was clearly perceived in the gustatory 

 parts of the tongue. Tick (1864), on the contrary, showed that 

 acids only excite the nerves of pain in concentrated solutions. 

 This agrees with v. Vintschgau's observations of 1880, that salt 

 solutions, sodium and ammonium chloride, and potassium iodide 

 could only act on the non -gustatory mucosa in concentrated 

 solutions, while in dilute solutions they are perceived solely in the 

 taste area. Kiesow (1894) showed that not only salt and acid, but 

 sweet and bitter as well, are accompanied by tactile sensations, 

 which in the highest degree of sweetness may become very 

 intense. 



From this it may be concluded that acid and salt, as well as 

 sweet and bitter, are true tastes. Nevertheless, Rouget (1875) 

 and Lannegrace (1878) admitted sweet and bitter alone to be true 

 tastes, and held that acid and salt were pseudo-tastes or chemical 

 taste sensations. This refinement, however, has no real foundation. 

 In fact, these authors themselves recognised that " dilute solutions 



