Elementary lessons on insects . elementarylesson00need Year: 1928 200 ELEMENTARY LESSONS ON INSECTS glass having its lower edge sunk in the soil of the pot, and a cheese-cloth cover. Small transparent insects, for examination with the micro- scope.—These may be obtained from any weedy, permanent pond, by lifting some of the floating 'pond scums' and trash with a small dip net and placing it in shallow white dishes in clean water. Damselfly and mayfly nymphs will quickly appear (along with water fleas and other minute aquatic animals) swimming around the edges of the dish. The damselfly nymphs
Elementary lessons on insects . elementarylesson00need Year: 1928 200 ELEMENTARY LESSONS ON INSECTS glass having its lower edge sunk in the soil of the pot, and a cheese-cloth cover. Small transparent insects, for examination with the micro- scope.—These may be obtained from any weedy, permanent pond, by lifting some of the floating 'pond scums' and trash with a small dip net and placing it in shallow white dishes in clean water. Damselfly and mayfly nymphs will quickly appear (along with water fleas and other minute aquatic animals) swimming around the edges of the dish. The damselfly nymphs will be recognized by the three flat, vertically placed platelike tracheal gills in which the body terminates; the mayfly nymph, by the paired gills on the back of the abdomen, one pair on each of the first seven segments. Midge larvae will also probably appear: minute worm- like creatures that swim jerkily, by means of figure-of-8 loopings of the body. Either will show what is wanted for this study. Choose the smallest and most transparent specimens to place under the microscope. Put them in hollow ground slides, or support the coverglass over them to avoid crushing. Use only living specimens. Fig. 72.—A lantern-globe live cage.
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