CHAPTER II: THE BALANCED AQUARIUM 

 AND THE SNAILERY 



A PRACTICABLE WAY TO STUDY MOLLUSKS ALIVE IN 



YOUR OWN HOME 



About fifty years ago a young lady up in Vermont took 

 home from a pond a two-quart glass jar of water in which she had 

 collected a few tadpoles, minnows and snails, and some of the 

 growing pond-weed among whose leafy stems she found them. 

 In her home she kept this happy family; the water did not stale 

 and grow turbid; the animals and plants throve as if they were 

 still in their native pond. 



The secret of her success was this. The leaves of submerged 

 plants give out oxygen which gill-breathing animals obtain from 

 the water. They take up the carbonic acid gas given off into the 

 water by the animals. Each kind of living thing needs the very 

 element that the other discards. Plants and animals "purify 

 the water" for each other. This balance of Nature is a nice one. 

 Too many animals or too many plants upset it. 



Fresh water aquaria are miniature ponds, tanks or jars stocked 

 with animal and plant life brought in from ponds or streams. 

 If properly "balanced," the water needs no changing but remains 

 pure and sparkling as long as the equilibrium is maintained. 

 This is the practicable aquarium for all who live inland. 



Marine, or salt water aquaria are feasible for all who live near 

 the seashore. The law of balance holds here, too. The difference 

 is that sea water is used, and seaweeds and the animal life of the 

 ocean furnish the proper materials for stocking it. Inland, there 

 have been some successful marine aquaria. But it is expensive 

 to ship sea water by rail, and making artificial sea water presents 

 many difficulties. The stocking of these aquaria is precarious 

 business. Successful marine aquaria inland are rare. 



Public aquaria, like the great institution in Battery Park, 

 New York, which is visited by thousands of people daily, maintain 



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