"When it is necessary to add water to an aquarium on account of loss by evaporation, rain water should be used to prevent an undue accumulation of the mineral-water held in solution in other water."
Fig. 168.—Battery-jar aquarium. (From Jenkins and Kellogg.)
Making collections.—Much is to be learned about animals by "collecting" them. But the collecting should be done chiefly with the idea of learning about the animals rather than with the notion of getting as many specimens as possible. To collect, it is necessary to find the animals alive; one learns thus their haunts, their local distribution, and something of their habits, while by continued work one comes to know how many and what different kinds or species of each group being collected occur in the region collected over. Collecting requires the sacrifice of life, however, and this will always be kept well in mind by the humane teacher and pupil. Where one set of specimens will do, no more should be collected. The author believes that high-school work in this line should be almost exclusively limited to the building up of a common school collection. Let a single set of specimens be brought together by the combined efforts of all the members of the class, and let it be well housed and cared for permanently. Each succeeding class will add to it; it may come in time to be a really representative exhibition of the local fauna.
The high-school collection should include not only adult specimens of the various kinds of animals, forming a systematic collection, as it is called, but also all kinds of specimens which illustrate the structure and habits of the animals in question and which will constitute a so-called biological collection. Specimens of the eggs and all immature stages; dissections preserved in alcohol or formalin showing the external and internal anatomy; nests, cocoons, and all specimens showing the work and industries of the various animals; in short, any specimen of the animal itself in embryonic or postembryonic condition, or any parts of the animal, or anything illustrating what the animal does or how it lives, all these should be collected as assiduously as the adult individuals. Each specimen in the collection should be labelled with the name of the animal, the date, and locality, and the name of the collector, with any particular information which will make it more instructive. If such special data are too voluminous for a label, they should be written in a general note-book called "Notes on Collections" (kept in the schoolroom with the collection), the specimen and corresponding data being given a common number so that their association may be recognized. In the following paragraphs are given brief directions for catching, pinning up, and caring for insects, for making skins of birds and mammals, and for the alcoholic preservation of other kinds of animals.
Fig. 169.—Insect killing-bottle; cyanide
of potassium at bottom, covered with
plaster of Paris. (From Jenkins and
Kellogg.)
Insects.—For catching insects there are needed a net, a killing-bottle, a few small vials of alcohol, and a few small boxes to carry home live specimens, cocoons, galls, etc. For preparing and preserving the insects there are needed insect-pins, cork- or pith-lined drawers or boxes, and small wide-mouthed bottles of alcohol.