STRUCTURE OF STEMS.—One- and two-year-old twigs of horse-chestnut, elm, and willow should be cut into half-inch lengths and distributed among the class. If cut straight across with a sharp pen-knife, the different layers can be seen with the naked eye. Afterwards these pieces should be slit longitudinally, and the various tissues peeled off by the pupils.

BULBS AND CORMS.—Bulbs of snowdrop and tulip, and corms of crocus, can be bought from seedsmen, from September to January, at from 6d. to 1s. per 100. At any other season of the year the onion will make a good substitute.

WILLOW TWIGS will root readily if placed in water and kept near the hot pipes in school.

VEGETABLE FINGERS.—To illustrate this lesson, peas (of any kind) ought to be grown in school. Branches of the many wild peas and vetches are to be found in abundance in every hedgerow during spring, summer, and autumn. Branches of Virginia creeper, clematis, tropÆolum (Indian cress) may be shown with advantage. The compound leaves of the rose, ash, or mountain ash should be shown along with those of sweet-pea and edible pea, and the amount of green (assimilating) area compared.

THE GREAT WATER BEETLE is found in nearly every pond. One or two should be kept and fed upon small worms. These beetles can also be obtained from any naturalist dealer. The larvÆ of this beetle is found in ponds in summer months.

“WATER BOATMAN” BEETLES (notonecta and corrixa) are common to all our ponds.

PLANT ARMOUR.—Branches of whin, bramble, hawthorn, and barberry, and leaves of holly, thistle, and nettle will be found to illustrate this lesson. Young whin plants are to be found plentifully in spring, growing under the old bushes. One of these should be grown in a pot in school and kept well watered. It will produce no prickles.

TROUT EGGS are obtainable from any of the fisheries—e.g., Howietoun Fisheries, Stirling, or Solway Fisheries, Dumfries, at about 1s. per 100, from October till April. They are easily hatched and reared wherever running water can be obtained. If not hatched in a bottle, as described in Lesson XIII., the ova ought to be placed in a shallow trough of perforated zinc suspended in a small wooden box. The inside of the box must be charred with a red-hot iron to prevent fungal growths. When the yolk-sac is completely absorbed, the young trout should be fed on yolk of hard-boiled egg, and, later on, on a mixture of this and chopped raw beef. In each case the food should be squeezed through perforated zinc.

“SILKWORMS.”—Eggs of the silk-bearing moth (Bombex Mori) can be had from Messrs Watkins & Doncaster, 36 Strand, London, and other dealers, at 4d. and 6d. per 100. The larva should be fed on mulberry or lettuce leaves, and the leaves should never be given wet.

Caterpillars of Tiger Moth (Arctia caja), Emperor Moth (Saturnia carpini), or Puss Moth (Cerura vinula) should be kept for comparison.