OR, THE HOME-CULTURE OF FRESH- WATER PLANTS. 



by bringing sand, also in his mouth, and placing it 

 upon the successive layers forming the foundation of 

 his edifice. His next process is to cement these layers 

 well together, by a gluten which he obtains from his 

 own skin, by rubbing himself against them; and thus 

 is formed the floor upon which the rest of the struc- 

 ture is to be raised. It is occasionally further secured 

 at its anchorage by a root or twig at the bottom of 

 the stream, or by some other accidental assistance. 

 His next process is to stick small, or occasionally 

 stronger materials, as uprights, all round the founda- 

 tion ; frequently taking them out with his mouth, 

 and putting them in situations more to his fancy, till 

 he is at length satisfied that they are all in the right 

 places. Sometimes he finds a portion of his mate- 

 rials altogether unsuitable, in which case he takes 

 it away to a distance from the intended nursery of 

 his offspring, and, regardless of labour and fatigue, 

 gets another lot of materials. He cements the walls 

 as they arise, by rubbing against them, as he had 

 done to the floor, and then sets about the roof, which 

 he completes in a similar manner. His hardest 

 work appears to be this cementing process; the 

 vibrating of the body, by means of which he exudes 

 the necessary mucus from the surface of the skin, 

 seeming to exhaust him very much. 



