Part 29 (2/2)
”Stoneworts, _Chara and Nitella_ (several species of each).
”Frog-spittle or water-silk, _Spirogyra_.
”A small quant.i.ty of duckweed, _Lemna_, placed on the surface of the water adds to the beauty of an aquarium.
[Ill.u.s.tration: FIG. 168.--Battery-jar aquarium. (From Jenkins and Kellogg.)]
”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 acc.u.mulation of the mineral-water held in solution in other water.”
=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 cla.s.s, and let it be well housed and cared for permanently. Each succeeding cla.s.s 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 ill.u.s.trate the structure and habits of the animals in question and which will const.i.tute 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, coc.o.o.ns, 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 ill.u.s.trating what the animal does or how it lives, all these should be collected as a.s.siduously 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 a.s.sociation 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.
_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, coc.o.o.ns, 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.
[Ill.u.s.tration: FIG. 169.--Insect killing-bottle; cyanide of pota.s.sium at bottom, covered with plaster of Paris. (From Jenkins and Kellogg.)]
The net, about 2 feet deep, tapering and rounded at its lower end, is made of cheesecloth or bobinet (not mosquito-netting, which is too frail), attached to a ring, one foot in diameter, of No. 3 galvanized iron wire, which in turn is fitted into a light wooden or cane handle about three and a half feet long.
The killing-bottle (fig. 169) is prepared by putting a few small lumps (about a teaspoonful) of cyanide of pota.s.sium into the bottom of a wide-mouthed bottle holding about four ounces, and covering this cyanide with wet plaster of Paris. When the plaster sets it will hold the cyanide in place, and allow the fumes given off by its gradual volatilization to fill the bottle. Insects dropped into it will be killed in from two or three to ten minutes. Keep a little tissue paper in the bottle to soak up moisture and to prevent the specimens from rubbing. Also keep the bottle well corked. Label it ”Poison,” and do not breathe the fumes (hydrocyanic gas). Insects may be left in it over night without injury to them.
b.u.t.terflies or dragon-flies too large to drop into the killing-bottle may be killed by dropping a little chloroform or benzine on a piece of cotton, to be placed in a tight box with them. Larvae (caterpillars, grubs, etc.) and pupae (chrysalids) should be dropped into the vials of alcohol.
In collecting, visit flowers, sweep the net back and forth over the small flowers and gra.s.ses of meadows and pastures, look under stones, break up old logs and stumps, poke about decaying matter, jar and shake small trees and shrubs, and visit ponds and streams. Many insects can be collected in summer at night about electric lights, or a lamp by an open window.
When the insects are brought home or to the schoolroom they must be ”pinned up.” Buy insect-pins, long, slender, small-headed, sharp-pointed pins, of a dealer in naturalists' supplies (see p. 453). These pins cost ten cents a hundred. Order Klaeger pins, No. 3, or Carlsbaeder pins, No.
5. These are the most useful sizes. For larger pins order Klaeger No. 5 (Carlsbaeder No. 8); for smaller order Klaeger No. 1 (Carlsbaeder No.
2). Pin each insect straight down through the thorax (fig. 170) (except beetles, which pin through the right wing-cover near the middle of the body). On each pin below the insect place a small label with date and locality of capture. Insects too small to be pinned may be gummed on to small slips of cardboard, which should be then pinned up. Keep the insects in drawers or boxes lined on the bottom with a thin layer of cork, or pith of some kind. (Corn-pith can be used; also in the West, the pith of the flowering stalk of the century plant.) The cheapest insect-boxes and very good ones, too, are cigar-boxes. But unless well looked after they let in tiny live insects which feed on the dead specimens. For a permanent collection, therefore, it will be necessary to have made some tight boxes or drawers. Gla.s.s-topped ones are best, so that the specimens may be examined without opening them. A ”moth-ball”
(naphthaline) fastened in one corner of the box will help keep out the marauding insects.
[Ill.u.s.tration: FIG. 170.--Insect properly ”pinned up.” (From Jenkins and Kellogg.)]
b.u.t.terflies, dragon-flies, and other larger and beautiful-winged insects should be ”spread,” that is, should be allowed to dry with wings expanded. To do this spreading- or setting-boards (figs. 171 and 172) are necessary. Such a board consists of two strips of wood fastened a short distance apart so as to leave between them a groove for the body of the insect, and upon which the wings are held in position until the insect is dry. A narrow strip of pith or cork should be fastened to the lower side of the two strips of wood, closing the groove below. Into this cork is thrust the pin on which the insect is mounted. Another strip of wood is fastened to the lower sides of the cleats to which the two strips are nailed. This serves as a bottom and protects the points of the pins which project through the piece of cork. The wings are held down, after having been outspread with the hinder margins of the fore wings about at right angles to the body, by strips of paper pinned down over them.
”Soft specimens” such as insect larvae, myriapods, and spiders should be preserved in bottles of alcohol (85 per cent). Nests, galls, stems, and leaves partly eaten by insects, and other dry specimens can be kept in small pasteboard boxes.
For a good and full account of insect-collecting and preserving, with directions for making insect-cases, etc., see Comstock's ”Insect Life,” pp. 284-314.
[Ill.u.s.tration: FIG. 171.--Setting-board with b.u.t.terflies properly ”spread.” (After Comstock.)]
_Birds._--In collecting birds, shooting is chiefly to be relied on. Use dust-shot (the smallest shot made) in small loads. For shooting small birds it is extremely desirable to have an auxiliary barrel of much smaller bore than the usual shotgun which can be fitted into one of the regular gun-barrels. In such an auxiliary barrel use 32-calibre sh.e.l.ls loaded with dust-shot instead of bullets. Plug up the throat and vent of shot birds with cotton, and thrust each bird head downward into a cornucopia of paper. This will keep the feathers unsoiled and smooth.
[Ill.u.s.tration: FIG. 172.--Setting-board in cross-section to show construction. (After Comstock.)]
Birds should be skinned soon after bringing home, after they have become relaxed, but before evidences of decomposition are manifest. The tools and materials necessary to make skins are scalpel, strong sharp-pointed scissors, bone-cutters, forceps, corn-meal, a mixture of two parts white a.r.s.enic and one part powdered alum, cotton, and metric-system measure.
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