ON THE TONGUE 543 



the rate of convalescence and the complete degree of 

 recovery of health attained. In reading and estimating 

 the characters imprinted on the tongue by nature and 

 disease respectively, we must include those of size, con- 

 sistency, colour, general appearance and arrangement of 

 papillary textures, local and general, presence or absence 

 of moisture, and local and general development of " fur,' r 

 and many other less prominent features of health and 

 disease. For our present purpose, however, it will be 

 sufficient if we deal with the last named, or " fur," as 

 being most intimately and generally connected with the 

 presence and effects of morbid processes or disease. 



The development of " fur " is not confined to the con- 

 ditions of disease, but may be found naturally present in 

 many people in the possession of excellent health ; we 

 must, therefore, regard its presence or absence as a matter 

 of less than vital importance, but yet a lingual feature of 

 the greatest diagnostic importance in those cases wherein 

 its presence is unmistakably a symptom. 



What, then, does " fur," or " furred tongue," signify in 

 the conditions of health and disease respectively ? 



" Fur " in the healthy is usually a local white or 

 yellowish super-epithelial deposit or exudation more 

 especially the latter occupying the back and central two- 

 thirds or so of the tongue's upper surface, and generally 

 thicker in the centre and thinning towards the edges. As 

 we have remarked, it is mostly to be regarded as an exuda- 

 tion. An exudation from where ? and an exudation of 

 what ? you will ask. As an exudation, of course, it can 

 only come from the epithelial covering of the tongue, with 

 its multitudinous array of papillary cups, and communi- 

 cating or attached endothelium-lined ducts of sub-com- 

 munication. The part of the tongue furred is that on 

 which these papillary epithelial arrangements are most in 

 evidence, and we may, therefore, assume that the process 

 of exudation is more active here than elsewhere, and hence 

 may regard the prevailing natural local " fur " production 

 as being due to increased local accumulation of exudate,. 

 with proportionately increased difficulty of its disintegra- 

 tion and detachment. 



The exudate may be looked upon as mucous or mucoid 



