CHAP. XV.] AFTEK-TASTES.- SUBJECTIVE PHENOMENA, 447 



there intermixed with a number of fungiform papillae sufficient to 

 account for the little that exists. Their structure and position, as 

 already remarked, lead to the same conclusion. It may be added, 

 that, in the lion, where these papillae are capped with spines, so thick 

 and rigid as totally to incapacitate them for taste, they are furnished 

 at the base with an additional tuft of soft secondary papillae, that 

 seem specially adapted for the latter function. It is possible that 

 certain soft papillae, which we have frequently seen springing up 

 about the base of the less developed filiform ones in the human 

 tongue, may contribute, in a similar manner, to the sense of taste. 



Are the Varieties of Taste referrible to the Varieties of the Papillae ? 

 It has been imagined that the differences of form met with in the 

 papillae might be in some special relation to the leading varieties of 

 tastes, as the bitter, sweet, sour, etc. ; but the careful experiments 

 of Horn on this interesting point can scarcely be considered as tend- 

 ing to establish such a correspondence. The difficulties, however, of 

 experimenting are so great, that neither can they be said to disprove it : 

 for a considerable extent of impression is necessary to ensure a per- 

 ception sufficiently definite to be relied on ; and the different papillae 

 are for the most part too much intermingled to admit of several of a 

 similar kind being tested apart from others. The most that can be 

 deduced from Horn's observations is, that more than three-fourths of 

 the substance he applied to the circumvallate papillae, including, we 

 suppose, the simple papillae we have described on the neighbouring 

 surface, excited a bitter taste, or one in which a bitter was asso- 

 ciated with some other, especially an alkaline or saline flavour ; and 

 that on the region where the filiform papillae abound the majority of 

 substances tasted acid, or acid with a mixture of bitter or sweet. 

 In regard to the fungiform variety no decided results were obtained. 

 These facts will perhaps help to explain the effect of the act of swal- 

 lowing in modifying and heightening flavours, since the food is 

 much more completely brought into contact with the papillae on the 

 base of the tongue during that act. 



After-tastes. Impressions of taste remain longer than those of the 

 other senses, because the fluids exciting them must of necessity con- 

 tinue for some time in contact with the nerves after having saturated 

 the intervening papillary investment. For the same reason it is diffi- 

 cult to say how much of the taste that lingers after the substance has 

 apparently left the mouth is due to the excitation of the nerves by 

 particles still remaining in the papillae, and how much to that state 

 of the nerves, which, in all the senses, prolongs the perception, after 

 the mere excitation has ceased. The taste left in the mouth by 



