APARTMENTS AND FURNITURE. 171 



kind of rooms of which I am now treating, 

 have communication with the open air, in such 

 a way that the air, in small quantity, can, and 

 probably does reach them ; and much more of 

 it would reach them, were they not so closely 

 filled as to prevent its admittance. 



But it is time for me to speak of these 

 apartments with more particularity. I have al- 

 ready shown you that all the cavities, or passa- 

 ges in the human body which open to the air, 

 such as the ears, nose, mouth, &c., are lined 

 with a membrane almost exactly like the skin, 

 only thinner. It has its thick layer, or real 

 skin, on a thin cellular layer ; then its soft thin 

 layer of pigment or paint, if this has any exist- 

 ence beyond the commencement of the open- 

 ings, say at the edge of the lips ; * then, and 

 lastly, its cuticle. 



This membrane is not called skin, however, 

 except on the surface. Its usual name is mucous 

 membrane, because it everywhere secretes on its 



* Anatomists are not agreed on this point. The 

 general opinion is, that this membrane which con- 

 tains the color does not exist at all in the internal 

 cavities of the body. 



