154 PHYSIOLOGY CHAP. 



means of a fine brush, the point of which was smaller than the 

 papillae. The sodium chloride solutions were soon abandoned, 

 because the resulting sensations were not sufficiently strong and 

 distinct. To accelerate the signalling of the sensations, the 

 subject was forewarned of the quality of taste to be excited. 



Oehrwall investigated the gustatory sensibility for sweet, 

 bitter, and acid on 125 papillae. He began by showing that the 

 mucous membrane between the papillae was insensitive to tastes, 

 and further found that 27 out of the 125 papillae examined did 

 not react to the test solutions. The 98 papillae accepted as 

 gustatory reacted as follows : 



To acid, 91. Exclusively to acid, 12. 



To sweet, 79. Exclusively to sweet, 3. 



To bitter, 71. Exclusively to bitter, 0. 



To sweet and acid, 72. Exclusively to sweet and acid, 12. 



To bitter and acid, 67. Exclusively to bitter and acid, 7. 



To sweet, bitter, and acid, 60. 



To sum up we may say that of the 98 gustatory papillae the 

 reaction was : 



To acid but not to sweet, 19. 

 To sweet but not to acid, 7. 

 To acid but not to bitter, 24. 

 To bitter but not to acid, 4. 

 To sweet but not to bitter, 15. 

 To bitter but not to sweet, 7. 



From these results we may conclude (a) that not all the 

 fungiform papillae of the apex of the tongue are gustatory ; (&) that 

 not all the gustatory papillae are sensitive to all the three tastes 

 investigated ; (c) that many (38 to 98) do not react to one or two 

 of the tastes. 



We must also bear in mind that there is another difference 

 between the various papillae though it is more difficult to estimate 

 it exactly; not all the papillae that are sensitive to a taste 

 appreciate it with the same intensity ; the reactions to each taste 

 may vary in strength in the different papillae. Consequently 

 the differences between one papilla and another are not merely 

 qualitative but are quantitative also. 



Oehrwall also experimented by the electrical stimulation of 

 isolated fungiform papillae with a brush electrode. He found 

 that an acid taste only appeared in the papillae which reacted to 

 acid. He failed to arouse a sweet or bitter taste, because in 

 order to avoid electrolytic effects he employed the induced current, 

 with which there is a sensation of warmth and of vibration that 

 disturbs the experiment. With the constant current Oehrwall 

 always obtained an acid taste at the anode and a sensation of 

 warmth in the papillae that were sensitive to acid. At the 

 kathode he obtained a bitter or sweet taste as well as a sensation of 



