SENSE OP TASTE. 869 



that the filiform papillae of Man seem to be the rudimentary forms of those 

 horny epithelial processes which acquire so great a development in the tongues 

 of the Carnivora, and which are of such importance in the abrasion of their food. 

 870. The simple application of a sapid substance to the gustative surface is 

 usually sufficient to excite the sensation ; and if this application be restricted 

 to one particular spot, we are able to recognize its place more or less distinctly. 

 In this respect, then, the gustative impression resembles 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 gustative sensibility is most acute; namely, 

 the apex, sides, and posterior part of the dorsum j 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 is moved 

 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 flavor 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 received into the mouth, their taste is most completely descriminated 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 ex- 

 altation of the usual effects is simply due to mechanical causes ; the sapid parti- 

 cles 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 contact 

 with the papillae. The impressions made upon our consciousness by a large 

 proportion of sapid substances are of a complex kind ; being in part derived from 

 their odorous emanations, of which we take cognizance through the organ of 

 Smell. Of this any one may convince himself, by closing the nostrils, and in- 

 spiring and expiring through the mouth only, whilst holding in the mouth, or 

 even rubbing between the tongue and the palate, some aromatic substance ; for 

 its taste is then scarcely recognized, although it is immediately perceived when 

 its effluvia are drawn into the nose. It is well known, too, that, when the 

 sensibility of the Schneiderian membrane is blunted by inflammation (as in an 

 ordinary cold in the head), the power of distinguishing flavors is very much 

 diminished. In fact, some Physiologists are of opinion that all our knowledge 

 of the flavor of sapid substances is received through the Smell ; but this, as 

 already shown, would not be a correct statement ; and there are cases on record 

 in which the sense of Smell has been entirely lost, without any impairment of 

 the true sense of Taste. 1 



1 An interesting case of this kind, occurring in a Negro who had gradually lost the 

 characteristic hue of his skin, and had acquired the fair complexion of a European, has 

 lately been put on record by Dr. J. C. Hutchison. The Olfactory nerve seemed to be en- 

 tirely paralyzed, whilst the branches of the 5th Pair retained their integrity ; so that, 

 whilst the proper sense of Smell was entirely lost, a pungent burning sensation was excited 

 by irritating vapors, and the application of snuif induced sneezing. Notwithstanding this 

 deficiency, the sense of Taste, properly so called, did not seem to be impaired ; for substances 

 which neither possessed odor nor pungency could be readily discriminated, even though 

 their tastes were not widely different. (See " Amer. Journ. of Med. Sci." Jan. 1852.) 



