918 GUSTATORY SENSATIONS. 



The proof of this is as follows: Oehrwall, and after him Goldscheider and 

 H. Schmidt, found that among the fungiform papillae some reacted to sugar, 

 but not to tartaric acid; some to quinin, but not to tartaric acid; and some to 

 quinin, but not to sugar. Electrical stimulation of some papilla? excited a bitter 

 taste, of others a salty taste, and of still others a sweet taste. With the constant 

 current, the purest sensation was at the anode. 



The leaves of Gymnema sylvestre, when applied to the tongue, destroy the 

 sensation of sweetness and bitterness. 



Continued stimulation of taste is followed by phenomena of fatigue for the 

 various taste-sensations. This fact may be readily explained by the assumption 

 of specific end-apparatus for the different categories of taste, which are present 

 in relatively different number on the various papillae. 



With regard to the character of the stimulation of the gustatory 

 nerves, no real advance has been made since the time of Democritus 

 (469 B. C.), who attributed the taste-impression to the form of the 

 tasting atoms. In order that a gustatory impression may be made, a solu- 

 tion of the substance in the fluids of the mouth is necessary, especially 

 if it is in a solid or gaseous state. The intensity of the gustatory sen- 

 sation depends: (i) Upon the extent of the surface affected, as Camerer 

 especially showed by placing the substance upon i, 2, 3 or 4 circum- 

 vallate papillae. By rubbing the substance into the furrows and between 

 the papillae (rubbing movements of the tongue in the act of tasting) 

 the perception is facilitated. (2) The concentration of the sapid 

 substance is of great importance. Valentin found that the following 

 series of bodies ceased to be tasted in the order stated, as they were 

 progressively diluted: sirup, sugar, salt, aloes, quinin, sulphuric acid. 

 Quinin can be diluted 20 times more than salt before it becomes tasteless. 

 (3) The time that elapses between the application of the substance 

 and the appearance of the sensation varies with different substances. 

 Salt is most quickly tasted (after 0.17 second), then sweet, sour and 

 bitter (quinin after 0.258 second). This is true also of mixtures of 

 these substances. The last-named substances produce the longest 

 after-taste. (4) The delicacy of taste is in the first place congenital 

 (the newborn infant is said to be able to distinguish qualities of taste), 

 but it can be greatly improved. Prolonged tasting of the same substance, 

 or of similar or of strongly tasting substances, quickly impairs correct gus- 

 tatory judgment. (5) The sense of taste is greatly assisted by the sense of 

 smell, and the one is often confounded with the other. Thus, musk and 

 asafetida affect only the organ of smell without stimulating the sense 

 of taste. Even the eye is capable of assisting the sense of taste by the 

 excitation of conceptions of familiar tastes. Thus, alternate testing 

 of red and white wine, with the eyes bandaged, soon results in uncer- 

 tai r ty 'o ^ The m st suitable temperature for taste lies between 10 

 and 35 C.; hot and cold water abolish taste temporarily. 



in^i P ll Ce t-., n the ton S ue suppresses temporarily all power of taste, co- 



anH fS y + b l tte / taSt ' chewin S the le aves of Gymnema sylvestre the bitter 



sweet tastes. Two per cent, sulphuric acid makes water taken subse- 



taste^wtt T et - ?ugar dissolved in a tasteless solution of salt or quinin, 



> sweeter then when dissolved in water. Children and the insane who 



n hv l" 1 ^ *? m f iimes be ^duced to partake of substances repugnant to 

 tnern by the smell of an agreeable perfume 



at the no3t?v/T " ^f^'-The constant current excites an acid sensation 



of the curre/t *S' u r Cl Smg and n P enin g- ** well as during the passage 



at the ne^v. nol ^ T^ 6 ' r m ^ correctl y an astringent-burning, sensation 



negative pole. This cannot be the result of electrolysis of the saliva, for 



