The Balanced Aquarium and the Snailery 



one of the useful aerators, and a favourite food of certain snails. 

 It can be checked in its growth by introducing more snails, or by 

 cutting off the light with a screen of yellow paper. Such a method 

 is much better than darkening the room. 



Probably no single locality would furnish all the pond plants 

 mentioned. But any natural pond should supply plenty of three 

 or four kinds. 



If possible get water from the pond which grew the plants. 

 If this is impracticable, use ordinary well or cistern water, or take 

 it from the city tap. 



Let the plants get used to their new station before you put 

 in the animals. Bubbles of air rising in the water show that all 

 is well. 



Mollusks of rivers and ponds are at home in the fresh water 

 aquarium, and live at peace with many other animal forms. 

 Snails will be found among the leaves and stems of floating and 

 submerged plants. 



The Pond Snails (Physa), one of the best kinds for the aqua- 

 rium, will mow the conferva from the sides of the tank and will 

 breed there, undisturbed, though fishes prey upon them. 



The Trumpet Snail (Planorbis), coiled flat like a watch 

 spring, a far lustier fellow, may be found in ponds and ditches. 



Lymncea is the name of several pond snails, whose dark, 

 handsome shells coil to the right. They are inactive, a contrast 

 to the ambitious, left-handed Physas. 



Paludina, the marsh snail, may be represented sparingly. 

 Clams will live quietly in the aquarium, travelling about when 

 they feel like it, ploughing with extended foot through the gravel. 

 Fishes, tadpoles and the little acrobatic Water Newt {Triton) 

 live happily with the snails and clams, if fed regularly. Stickle- 

 backs will build nests and hatch their young. Avoid fish over 

 three inches long. 



Crayfish are best kept in separate jars; they are beasts of 

 prey and disturbers of the peace, attacking the fish and uprooting 

 the plants. With bits of rock they build caves in which to hide. 

 Small bits of meat will be eaten by crayfishes and tadpoles. 

 Insects, including "wigglers" from a neglected rain barrel (mos- 

 quito larv^) will be eaten by the fishes. They will pick up bread 

 crumbs. Small creatures we overlook entirely furnish food for 

 larger animals. 



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