Literary Notices. xi 



below those noted under i. Only on the soft palate does salt reach 

 the normal given. 



3. A single investigation showed that in childhood all parts, ex- 

 cepting the tip and edges of the tongue, possessed nearly the same 

 sensitiveness with regard to sweet. The tip and edges were more 

 sensitive. 



4. The explanation of the normal condition, as of individual 

 differences is without doubt to be found in the law of adaptation, ex- 

 cepting those cases in which pathological causes, obstructions, etc., 

 appear. 



Further, attention was directed to the qualitative conditions of 

 the sensations of taste. These experiments were only made on adults. 

 First, I was enabled to prove that all four above-named qualtities 

 are true sensations of taste, also that the sensations of sour and salt 

 must not be excluded from the sphere of taste on account of the 

 accompanying tactile sensations. On the contrary, my investigations 

 led to the conclusion that all our perceptions of taste are accompanied 

 by tactile sensations, although in different degrees. Sweet is accom- 

 panied on and near the limen by a sensation of smoothness, at higher 

 intensity by that of slipperiness, at very great intensity by that of 

 scratching and biting. The liminal values of bitter are accompanied 

 by a distinct sensation of greasiness. Even the application of dis- 

 tilled water produced with some of my subjects a distinct perception of 

 taste. Two of them tasted water on the tip of the tongue as sweet, 

 on the edges as sour and sourish, at the base bitter. Others tasted 

 it as bitter in the whole cavity of the mouth, others only bitter at the 

 base and tasteless on the other parts of the tongue. The bitter sensa- 

 tion produced by distilled water accompanied the single sensation 

 called forth by taste — substances often for a time above the limen, so 

 that in this way two sensations arose which I have designated as 

 double-sensations. Even a mechanical stimulus of the base of the 

 tongue with a glass rod produced with me and with many of my sub- 

 jects a sensation distinctly bitter. 



Great influence in the region of taste must be ascribed to asso- 

 ciation and the effects of contrast. The conditions of contrast I in- 

 vestigated withfspecial care ; the total results of which may be given 

 concisely as follows : 



1. Contrasting stimuli must be recognized in the sense of taste. 



2. Salt contrasts with sweet, salt with sour, sweet with sour. 



3. Salt and sweet, and salt and sour contrast both on simultane- 

 ous stimulation of corresponding parts of the tongue and on succes- 



