AQUARIUM. 27 



tin six-eighths of an inch wide, double thick glass for the bot- 

 tom and good ordinary glass for the sides and ends. In the 

 book last named, which gives specifications for making aquaria 

 of different sizes, the following recipe for making cement for 

 the angles is quoted from the U.S. Fish Commission: "stir 

 together dry, by weight, eight parts putty (dry whiting), one 

 part red lead, and one part litharge. Mix, as wanted for use, 

 with pure raw linseed oil, to consistency of stiff putty. Nar- 

 row strips of glass may be used to ' face ' the cement along 

 the inside corners ; these protect the cement and brace the 

 glass sides. 



In stocking the aquarium start with two or three inches 

 of washed sand into which place some water plants such 

 as water-moss or anacharis. Place shells or stones at the 

 roots. Use care in filling up the box with water so as 

 to avoid displacing the plants. Add tadpoles, water-snails, 

 minnows, guarding against overcrowding. With a proper 

 adjustment of animal and green plant life the water will 

 not need to be changed. The green plants exhale oxygen 

 to supply the needs of the animals and the carbon dioxide 

 breathed out by the animals is used up by the plants. There 

 is temptation to put in too many specimens of both classes but 

 particularly too many animals. Each full-sized minnow or 

 shiner, for example, should have a half-gallon of water. 

 Fishes ought not to be given more food than they eat up 

 clean. Once a day is often enough to feed them. Keep the 

 box away from direct sunlight. If slimy growths appear 

 put in more water-snails. 



Frogs, small snakes, tree-frogs and salamanders can be kept 

 in 'gem jars' by replacing the glass top with one or two wire 

 discs of suitable size. There should always be some water in 

 the jar where frogs are kept. A saturated sponge or damp 

 moss should be put in the jar containing tree-frogs or sala- 

 manders. In nature, cold-blooded animals feed irregularly. 



