284 LECTURE VI. 



mention, that the surfaces of fish are 

 smeared over with mucus, which is libe- 

 rally poured out from the orifices of nu- 

 merous ducts, rendering the surface of 

 these animals particularly slippery, pre- 

 venting also any adhesion between them 

 and the element in which they move, and 

 serving the same purpose in facilitating 

 their transit through the water, that greas- 

 ing the bottom of a boat is known to do. 

 Yet though they swim through the water 

 with such celerity, the skin is never de- 

 nuded of mucus. 



There are intermediate surfaces in ani- 

 mal bodies, between those which I have 

 described as external and internal skins, 

 and these are also defended by appropriate 

 lackers, which, however, I shall not de- 

 tain you by describing. Yet I wish you to 

 observe, how admirably the cerumen of the 

 ear is adapted, from its obvious qualities, 

 to defend and keep moist that process of 

 the skin which lines the tube of the ear. 

 Its tenacity causes it to cling to the surface 

 it is designed to protect; it is not liable to 



