48 



After an aquarium has been filled with water and the inhabitants 

 well estabhshed it is not necessary to change the water, except in case 

 of accident. The water that is lost by evaporation has to be poured 

 in gently, a little at a time, in order not to disturb the water and 

 destroy its clearness. If a piece of rubber tubing is available, a 

 practical use of the siphon can be shown and the aquarium replenished 

 at the same time. It is a good plan to use rain water, or clear water 

 from a pond, for this purpose. 



A piece of thin board or a pane of glass may be used as a cover to 

 keep the dust out of the aquarium. This need not fit tightly or 

 be left on all the time. A wire netting or a cover of thin cot- 

 ton net would keep the flying insects from escaping, and might 

 be tied on permanently. Dust may be skimmed off the top of the 

 water or removed by laying pieces of blotting paper on the surface 

 for a moment. 



If any of the inhabitants do not take kindly to the life in the 

 aquarium, they can be taken out and kept in a jar by themselves — 

 a sort of fresh air and cold water cure. If any chance to die, they 

 ought to be removed before they make the water unfit for the others. 

 Bits of charcoal in the water are helpful if a deodorizer or dis- 

 infectant is needed. 



)• 10. 2. — W rectangular glass aquarium. 



