LECTURE VI, 283 



we tear the bulbs of the hair from the beds 

 in which they grew, and they remain firmly 

 connected to the cuticle in consequence of 

 this investment. 



There are processes of the skin entering 

 the interior of animals ; and though these 

 differ materially from it in appearance, yet 

 an analogy of structure may be traced in 

 them, so that they may fairly be considered 

 as internal skins. Their surfaces, to which 

 also the air may have access, are every 

 where besmeared with mucus, and there- 

 fore they are commonly called the mucous 

 membranes of animals. Mucus is an ani- 

 mal substance, admirably adapted for the 

 defence of the surfaces which it covers. It 

 is mild and unstimulating, possessing a 

 viscidity which causes it to cling to the sur- 

 face it is designed to defend, and being 

 particularly immiscible with other fluids, it 

 is not likely to be removed by the liquids 

 contained in cavities formed of such mem- 

 branes, or even by the current of fluid 

 when passing through tubes of the same 

 construction. In evidence of this, I may 



