TASTE. 



861 



undergo a kind of erection when sapid sub- 

 stances are brought into contact with them. 

 This inference is in complete harmony with 

 the relative acuteness of the senses of taste 

 and touch, in the portions of the surface on 

 which the one or the other class of papillae 

 is most abundant ; thus the sides and back 

 part of the tongue are unquestionably the 

 parts where the gustative sensibility is the 

 greatest, and it is there that the fungiform, 

 circumvallate, and simple papillae are most 

 thickly set; whilst the apex and central part 

 of the dorsum, over which the tactile sensi- 

 bility is predominant, is that on which we 

 meet with the largest number of filiform 

 papillae. Whether there be any difference 

 among the simple isolated papillae, and among 

 those which are aggregated into the com- 

 posite bodies that are termed fungiform and 

 circumvallate, we are scarcely in a con- 

 dition even to form a guess, until it shall 

 have been determined whether the gustative 

 and tactile nerve-fibres are identical or diverse 

 in their endowments. If the former, it will 

 be reasonable to suppose that every papilla 

 through which a gustative impression can be 

 made in virtue of the penetration of sapid 

 matter into its tissue, may also be subservient 

 to the reception of tactile impressions from 

 mechanical stimulation. On the other hand, 

 if it should be proved that the gustative sense 

 depends on a special set of fibres, we should 

 still have to inquire whether the same papilla 

 may not contain fibres of both classes, so as to 

 minister to both functions ; or whether some 

 of the papillae are purely gustative, whilst 

 others are purely tactile. 



At present there is no adequate reason to 

 suppose that there is any essential difference 

 of function among the papilla? covered with a 

 soft thin epithelium, whether these be solitary 

 or aggregate. An attempt was made by 

 Horn * to establish some such diversity ; but 

 the results of his experiments would rather 

 lead to the supposition that there is a dif- 

 ference in the gustative sensations excited by 

 the same substance, according as it is applied 

 to different regions of the tongue, than to 

 different papillae. Thus he found that more 

 than three-fourths of the substances which he 

 applied to the circumvallate papillae excited 

 a bitter taste, or one in which a bitter was 

 associated with some other flavour, especi- 

 ally an alkaline or saline ; whilst the majority 

 of the substances applied to the filiform 

 papillae tasted acid, or acid with a mixture of 

 bitter and sweet. But since, as we have 

 seen, mere mechanical stimulation produces 

 different gustative sensations according to the 

 part of the tongue to which it is applied, it is 

 probable that the difference in Horn's results 

 is not to be set down to the account of the 

 papilla 1 , but rather to that of the nerves by 

 which they are respectively supplied. 



Exercise of the Sense. The simple appli- 

 cation of a sapid 1 substance to the gustative 

 surface is usually sufficient to excite the sen- 



* Ueber den Geschrnacksinn des Menschen. 

 delberg, 1825. 



Hei- 



sation ; and if this application be restricted 

 to one particular spot, we arc able to recog- 

 nise its place more or less distinctly. In this 

 respect, then, the gustative impression resem- 

 bles the tactile ; for whilst we cannot, by our 

 own consciousness, distinguish the parts of 

 the retina or of the auditory apparatus on 

 which visual or auditory impressions are 

 made, we can make this distinction in regard 

 to the surface which is supplied by the 

 nerves of general sense. This determination 

 is most precise when the impression is made 

 on the parts of the tongue of which the gus- 

 tative sensibility is most acute ; namely, the 

 apex, sides, and posterior part of the dorsum; 

 being probably aided, however, near the tip, 

 by the acuteness of its tactile sensibility. The 

 impressibility of the middle portion of the 

 dorsum is greatly inferior ; but still, when 

 the gustative sensation has been excited 

 there, it is referred to the spot on which the 

 sapid substance was laid. The contact of 

 sapid substances much more readily excites a 

 gustative sensation, when it is made to press 

 upon the papillae, or to move over them. 

 Thus there are some substances whose taste 

 is not perceived when they are simply applied 

 to the central part of the dorsum of the 

 tongue, but of whose presence we are at once 

 rendered cognizant by pressing the tongue 

 against the roof of the mouth. The full 

 flavour of a sapid substance, again, is more 

 readily perceived when it is rubbed on any 

 part of the tongue, than when it is simply 

 brought in contact with it or pressed against 

 it. Even when liquids are taken into the 

 mouth, their taste is most completely discri- 

 minated by causing them to move over the 

 gustative surface: thus the "wine-taster" 

 takes a small quantity of the liquor into his 

 mouth, carries it rapidly over every part of 

 its lining membrane, and then ejects it. It is 

 not improbable that this exaltation of the 

 usual effects is simply due to mechanica 

 causes ; the sapid particles being brought by 

 the pressure or movement into more rapid 

 and complete operation on the nerve-fibres, 

 than they would be if simply placed in con- 

 tact with the papillae. 



As in the case of the other senses, so do 

 we find with regard to that of taste, that 

 continual attention to its indications greatly 

 increases its acuteness. Thus the " tasters '" 

 of wine, tea, &c., acquire a power of discrimi- 

 nation which is truly wonderful to those who 

 have not exercised themselves in the same 

 manner. Thus we have been informed that 

 the "taster" to one of the extensive cellars 

 . of sherry wines at Cadiz or Seville has not 

 the least difficulty in distinguishing the butt 

 from which a given sample may have been 

 drawn, although the number of different va- 

 rieties of the same kind of wine under his 

 keeping may not be less than five hundred. 

 So we are informed by Dr. Kitchener that 

 many London epicures are capable of saying 

 in what precise reach of the Thames the 

 salmon on the table has been caught; and the 

 Parisian gourmet is said to be able to distin- 



