Ill 



THE SENSE OF TASTE 



137 







Schreiber, we must remember that his results were obtained from 

 one individual only. According to v. Vintschgau and others, the 

 four qualities of taste cannot be distinguished equally well by all 

 persons at the tip of the tongue. Some find difficulty in dis- 

 tinguishing the different tastes ; others can only discriminate 

 between certain of them ; in others again the tip of the tongue is 

 insensitive to all tastes. At the base, on the contrary, every 

 one is normally able to distinguish the primitive qualities of 

 taste. 



The methodical exploration of the whole surface of the tongue 

 made by Kiesow (1894) in Wundt's laboratory altered the some- 

 what vague and uncertain ideas that prevailed on this subject. 

 According to Kiesow the tip of the tongue 

 is most sensitive to sweet tastes, acid is 

 best perceived at the sides, bitter at the 

 base, while the sensibility to salt is approxi- 

 mately equal over the whole gustatory 

 surface, though somewhat less at the base 

 than at the apex and sides. Kiesow further 

 established that sensibility to salt is practi- 

 cally the same in different individuals, and 

 that where individual differences occur 

 they are insignificant. 



The portion of Kiesow's work that bears 

 on our present subject was resumed by Fl< j 

 Hanig (1911). While Kiesow had confined 

 himself to determining the sensibility of 

 the different lingual gustatory regions on 

 the tongue, Hanig, continuing this research, 

 established isogustatory zones with parallel 

 margins, which he terms isocliymes for the 

 whole gustatory area, and carefully in- 

 vestigated the exact liminal value of the sensory points in each 

 zone. The different sensibility to the four primitive tastes in the 

 different gustatory regions of the tongue is shown in different 

 colours in Fig. 61. A glance at Hanig's diagram brings out the 

 following important facts, which, on the whole, confirm those dis- 

 covered by Kiesow : 



(a) Sensibility to sweet is greatest at the tip of the tongue, 

 least at the base. Sensibility to this taste diminishes not only 

 from the tip along the edges of the tongue, but also centripetally 

 from the periphery towards the oval central zone, which is in- 

 sensitive to taste. 



(&) The maximal sensibility to bitter lies in the region of the 

 circumvallate papillae, its minimum at the tip of the tongue and 

 at the neighbouring portions of its edge. The capacity of per- 

 ceiving this taste diminishes rapidly at first from the base to the 



. Diagram of region 

 which is insensitive to various 

 tastes on the dorsal surface of 

 the tongue. (Schreiber.) The 

 finely dotted oval area is in- 

 sensitive to all tastes ; the 

 area surrounded by an un- 

 broken line is insensitive to 

 sweet ; by a broken line to 

 salt ; by a dotted line to 

 bitter; by a line formed of 

 small circles to acid. 



