150 SMELL, TASTE, ALLIED SENSES 



to this subject. Their work shows that the four tastes 

 have decidedly individual distributions on the tongue. 

 The sour taste is best developed on the lateral edges of 

 the tongue and diminishes from these regions toward the 

 tip, the base, and the central' anaesthetic area (Fig. 36, A). 

 The saline taste is most pronounced at the tip and on 

 the lateral margins of the tongue and diminishes at the 

 base; toward the central area it ends rather abruptly 

 (Fig. 36, B). The bitter taste is most characteristic of the 

 base of the tongue especially in the region of the vallate pa- 

 pillae whence it diminishes rapidly toward the central area 

 and over the lateral edges to the tip (Fig. 36,C). The sweet 

 taste is at its maximum at the tip of the tongue and di- 

 minishes thence along the lateral margins to the base (Fig. 

 36, D). Thus sour is represented by two marginal re- 

 gions, saline by a horse-shoe shaped area at the tip, bit- 

 ter by a single center at the base, and sweet by one at 

 the tip. It is difficult to explain these differences in the 

 distribution of the tastes except on the assumption of 

 an independent sensory mechanism for each taste. 



This interpretation of taste is strengthened by what 

 has been learned from the local stimulation of the tongue. 

 Oehrwall (1891) mapped out a group of fungiform papillae 

 near the tip of the tongue in such a way that the 

 individual papillae could be reidentified and studied. 

 Each papilla was stimulated by applying to it the point 

 of a very fine brush loaded with a strong solution of a 

 given substance. The substances used were tartaric 

 acid 2 per cent, common salt 20 per cent, quinine hydro- 

 chloride 2 per cent, and sugar 40 per cent. The salt was 

 finally abandoned because of the indistinctness of the 

 sensation. In all 125 easily identifiable papillae were 



