The Management of River Tanks . 257 
To keep any of the higher kinds of fresh-water vegetation in health the 
tank must be placed in a window, which, in respect to all the rest of its con¬ 
tents, is the very worst place for it. By the way, it is fortunate that aquaria 
should be kept away from windows, for those who have a taste for such things 
are constantly tempted to block up all their windows with tanks and fern- 
cases, to the injury of their health by the loss of light and air which 
should have free access to every apartment. Provided the tank is well 
RIVER TANK, CONTAINING GOLD CARP, ROACH, AND MINNOW ; VALLISNERIA SPIRALIS 
ANACHARIS ALSINASTRUM, AND FLOATING FROG-BIT 
made and placed upon a stand well able to bear it, the form is not ot 
much consequence, but a plain rectangular figure is for all general purposes 
to be preferred, because, in a case like this, the form of the vessel should 
be subordinated to its use, and we want the best view possible of its 
contents. 
The “ natural system ” of tank management, as its name implies, is 
the only one by which satisfactory results of a permanent nature are to 
be obtained. The history of aquaria in the most extensive sense is simply 
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