THE HOUSE 1 LIVE IN. 



surface more or less oT a substance which is 

 called mucus. 



EXTERNAL EAR. The passage into the ear, 

 as we have already seen, is lined with this 

 membrane. But this passage or cavity is so 

 small that it can hardly be called an apartment. 

 The cavities connected with the nose are of 

 much more consequence. 



CHAMBERS OF THE NOSE. These, as we 

 have seen, are 1. The hollow but very irreg- 

 ular passage of the nose itself. 2. The cavity 

 in each cheek bone. 3. The cavity in the 

 forehead, or on each side of the root of the 

 nose. All these cavities are real cavities ; for 

 they are situated in hollows in the bones, and 

 therefore their sides cannot fall together and 

 close up the space. 



All these cavities, moreover, become in some 

 cases the seat of painful diseases. The nose 

 is subject to the polypus a pear-shaped swell- 

 ing with a narrow neck. This sometimes 

 renders our breathing difficult ; and if not ex- 

 tracted, has been known to go farther, and be- 



