LEAFLET XII.
LIFE IN AN AQUARIUM.[16]
By MARY ROGERS MILLER.
There is no more fascinating adjunct to nature-study than a well-kept aquarium. It is a never-ending source of enjoyment, interest and instruction to students of any age. Children in the kindergarten or at home will watch with delight the lively occupants, which cut all sorts of queer capers for their amusement, and older people may read some of nature's choicest secrets through the glassy sides of the little water world. To many, the word aquarium suggests a vision of an elaborately constructed glass box, ornamented with impossible rock-work and strange water plants, or a globe in which discouraged and sickly-looking gold-fish appear and disappear, and take strange, uncanny shapes as they dart hither and thither.
Such forms of aquaria have their place in the world, but they are not suited to the needs of an ordinary school-room. Every school may have some sort of an aquarium if the teacher and pupils are willing to give it some daily thought and care. Without such attention a fine aquarium may become an unsightly and disagreeable object, its inhabitants unhealthy and its beauty and usefulness lost.
The great fundamental principle underlying success in making and maintaining an aquarium is this: imitate nature. We all know how much easier it is to formulate a principle, and even to write a book about it, than to put it into practice. Most of us have not had the time and opportunity for the close observation of nature necessary to interpret her methods and to imitate her. It is to those teachers who are anxious to learn what nature has to teach and who wish to lead their pupils to a higher and wider conception of life, that these suggestions are offered.
Four things are important in making and keeping an aquarium:
1. The equilibrium between plant and animal life must be secured and maintained. It is probable that an aquarium in an elementary school is mainly used for the study of animal life; but animals do not thrive in water where no plants are growing. Nature keeps plants and animals in the same pond and we must follow her lead. The plants have three valuable functions in the aquarium. First, they supply food for the herbivorous creatures. Second, they give off a quantity of oxygen which is necessary to the life of the animals. Third, they take up from the water the harmful carbonic acid gas which passes from the bodies of the animals. Just how the plants do this is another story.
Fig. 55. A museum-jar aquarium. (More animal life would make a better equilibrium.)