OR, THE HOME-CULTURE OF FRESH-WATER PLANTS. 
by bringing sand, also in bis month, and placing it 
npon the successive layers forming the foundation of 
bis 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 necessarv mucus from the surface of the skin, 
seeming to exhaust him very much. 
