62 FRESH-WATEE AQUABIA. 



This tank should be oblong, with four glass sides, and its 

 bottom ought to be covered to a depth of at least 4in. with rich 

 garden moidd, over which there must be about an inch of gravel. 

 In this about a dozen plants should be carefully set, and the 

 vessel properly filled with clean soft water, of not too cold a 

 temperature. The glass sides ought to be shaded with four 

 pieces of board or slate, to prevent the light from causing an 

 excess of confervae. The object of having transparent sides is, 

 that the growth of the VaUisneria may be easily seen by re- 

 moving the shading; and thus anything that is wrong may 

 be readily discovered, and quickly put right before much 

 damage has been done. The top of the tank should be covered 

 with a piece of glass, raised Jin. above the edge by means of 

 two wooden slips. Many years ago I bought twelve plants 

 through the medium of The Bazaar, growing them in the 

 manner just described, and though th^re lived in the tank a 

 large favourite old carp, the VaUisneria grew to profusion ; 

 and notwithstanding that, from time to time, I took a great 

 deal out with which to stock other tanks or to give to friends, 

 the supply was always equal to the demand. 



The following precautions should be taken in regard to the 

 cultivation of VaUisneria spiralis, and iadeed almost any kind 

 of water-plant : 



1. Do not place it in too little light, or it will not flourish ; nor 

 in too much, or it will be choked with confervse. 



2. Do not chill it by putting it in water much colder than that 

 to which it has been accustomed. ' 



3. Do not let any rusty leaves remain on the plants, but cut 

 them off close to the roots. 



4. Do not stock the aquarium with any animals until the 

 Yallisneria has begun to grow ; and when the tank is stocked, be 

 careful to remove those creatures which show a disposition to 

 feed upon this particular plant. 



The VaUisneria is one of the best of aU water-weeds for pro- 

 ducing oxygen, therefore it is weU worth careful management. 

 The female plant seems to be much commoner than the male, 

 but it is not necessary to have the latter in cultivation, as the 

 former wUl readily increase by means of ofEshoots. 



