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The Management of River Tanks . 259 
grand groups of algae ; and as for the animals, the thin film of water over 
them, and their recent travel and subsequent transference from their places 
in the tanks, caused just enough of that peculiar irritation which seems to be 
needful to cause a full display of the beauties of certain of the radiates, and 
the audience had the advantage of beholding star-fishes, plumose anemones, 
and other marine subjects, in the attitudes they habitually assume when 
safely anchored fathom deep in ocean brine. 
The natural system is an imitation of nature, not in outward appearances 
merely, but in conditions. Tanks managed on the natural system may be 
AQUARIUM AND FERNERY COMBINED 
made to have a most beautiful appearance, and form an appropriate item in a 
“ home of taste.” But it is impossible to use such vessels for show purposes; 
any disturbance of the furniture would be a violation of the most essential 
conditions, and mere decorations are not to be tolerated; they are, in fact, for¬ 
bidden by the laws on which the system is based. How do we proceed to carry 
out the natural system ? We form within a vessel or vessels a group or groups of 
objects in imitation of rock pools, running streams, lakes, ponds, and so 
