EXTRACT LI. A. 



ON THE ROOF AND FLOOR OF THE MOUTH, AND 

 THE TONGUE. 



THE roof of the mouth is a partly irregularly ridged and 

 partly smooth mucous membrane covered surface, against 

 which the upper surface of the tongue is more or less 

 constantly laid, and between whose surfaces there is 

 more or less constant friction, and consequent epithelial 

 denudation. 



In the apposition of the surfaces a greater or lesser 

 degree of discomfort is experienced, unless a certain 

 amount of moisture is included in the inter-space. This 

 moisture may be obtained to a certain extent from the 

 surfaces themselves, or from the saliva flowing from 

 the ducts of the various glands opening into the cavity of 

 the mouth at various levels. 



In the situation of the parts, as thus viewed, it will be 

 observed that the salivary ducts open into the mouth at 

 a lower level than that of the upper surface of the tongue 

 when opposed to the palatal roof; hence a difficulty is 

 experienced in keeping the appropriate amount of mois- 

 ture supplied when that organ is at rest in that position. 



This apparent difficulty would be met, or would not 

 arise, were a sufficient supply always forthcoming from 

 either of the surfaces mentioned, and could it be available 

 in that condition the condition of rest or, for that part 

 of it, in any or all of their conditions. 



As meeting this want, and affording this supply, we 

 are of opinion that we see it, and sometimes feel it, at 

 the slight eminence situated at the exit of the anterior 



