THE CARE OF HOME AQUARIA 15 



run by water power, some by small electric motors, some by 

 weights or clockwork, etc., and of course all of them have been 

 patented. They have this advantage, that a larger number of 

 fishes may be maintained in a given quantity of water than is 

 possible in the balanced aquarium. But in the opinion of the 

 writer this display of inventive genius has been largely mis- 

 directed, for the properly balanced home aquarium will support 

 a sufficient amount of animal life for all ordinary purposes 

 without artificial aeration. Besides the balanced aquarium is 

 much more instructive since it approaches more nearly to natu- 

 ral conditions. 



The balance of plant and animal life means complete and 

 continual ventilation. Not only is oxygen supplied in sufficient 

 quantities by the plants, but the carbon dioxide given off by the 

 animals in respiration is consumed by the plants in the process 

 of starch making. The adjustment is Nature's own and all 

 animals are adapted to it. Such an arrangement is a pond iri 

 miniature and may be used in the scientific study of aquatic life 

 of various kinds. In the majority of cases, to be sure, only gold- 

 fi.shes are kept, in addition to a few tadpoles or snails and plants. 

 According to the interests of the aquarist, however, this may be 

 varied indefinitely. Many other attractive exotic fishes of strik- 

 ing colors, form and habits may be readily secured from dealers, 

 or the collector may take up the study of local native fishes, the 

 natural history of which will be found no less interesting than 

 that of the exotic species. 



Aquatic insects afford a most interesting and almost infi- 

 nitely varied field for study, and their habits, metamorphoses, 

 etc., may be most readily investigated by this means. Again, if 

 the aquarist is interested in aquatic botany, he will find here 

 excellent opportunities and means for studying m.ary water 

 plants. Marine life is even more varied than that of the fresh- 

 water, and endless opportunities are afforded to those who live 

 within reach of the sea. The microscopist will also find a con- 

 stantly changing and ever interesting field of research in the 

 minute life of the aquarium. 



As an adjunct to the scientific laboratory, the aquarium has 

 become a necessity. Here it may vary in size from the common 

 finger-bowl for minute animals to tanks for the larger forms. 

 The various aquatic laboratories such as those at Wood's Hole, 

 Massachusetts, and at Naples in Italy, to cite two of the best 

 known, make constant use of aquaria and could scarcely exist 



