446 INNEEVATION. [CHAP. xv. 



tlie extent of surface acted on ; and it is also heightened by the 

 motion and moderate pressure of the substance upon the gustatory 

 membrane. By the latter movements, the mucus and outer layers 

 of the epithelium are removed, and the sapid material is brought into 

 closer contact with the papilla. The act of swallowing seems 

 further necessary to the perfect appreciation of flavours. This is 

 partly explained by considering how much the concurrent exercise 

 of smell exalts the sense of taste. Most sapid substances, though in 

 different degrees, affect the nose through the throat on being swal- 

 lowed; and we are thus led to attribute to taste much of what is in 

 reality due to smell. The nurse's device of holding the nose of the 

 child in giving it disagreeable medicine, though commonly said to 

 deaden taste, seems rather serviceable by excluding smell. Thus 

 tested, taste is a less acute and definite sensation than most per- 

 sons imagine. Nevertheless, the difficulty of discriminating between 

 the two senses indicates a real, though obscure, alliance between 

 them, rendered closer by habit and association. 



The impression of cold air deadens the sense of taste, and has, we 

 believe, been the source of some of the discordance in the recorded 

 results of experiments. Cold acts similarly on touch. 



Do Taste and Touch co-exist in any of the Papilla ? A papillary 

 structure is, essentially, an arrangement for increasing the surface 

 by which a membrane may have contact with external substances ; 

 and, while the analogy with the skin leaves no doubt that this 

 structure in the tongue is concerned in the exquisite touch enjoyed 

 by the organ, it is almost as certain that it is also concerned in 

 taste. The question then arises whether touch and taste reside in 

 the same papillae or in distinct ones. 



Now it is possible, as far as we know, that nerve-fibres of different 

 endowments may be associated in the same papillae, and therefore 

 that one and the same papilla may possess both capacities. Taste, 

 however, it is evident, demands a more delicate external apparatus 

 in connexion with its nerves than touch ; so that touch might be exer- 

 cised with an apparatus adapted to taste, though not in all cases the 

 reverse. As far, therefore, as regards the simple papillae at the base 

 of the tongue, and those covering the circumvallate and fungiform 

 varieties, it seems impossible, in our ignorance of any anatomical 

 distinction between the nerve-fibres of the two endowments, to decide 

 whether the two senses are or are not resident together in the same 

 papillae. But there are good grounds for supposing that the conical 

 or filiform papillae are not designed for taste. They are most largely 

 developed in a part of the tongue where taste is feeblest, and are 



