Here we are at a stream; do you see those things at the bottom slowly moving? They seem to be bits of stick. "I know what they are," said Jack, "there is a good fat maggot in each of these cases; they are caddis-worms." Quite right, and in time they will change to insects. Here is another kind; the house is made of small bits of gravel, and it is attached to this smooth stone. I will break open the case; do you see inside is a long cylindrical case, with a thin covering; I slit this open with my penknife, and now you see the creature inside. There are a great variety of these caddis-worms, and most interesting it is to notice the different kind of houses they build. Some of the larvae live in movable cases, as we have seen, some in fixed habitations; the materials, too, out of which the different cases are constructed, are different, sometimes they are bits of gravel, or sand, wood, leaves, grass, the empty shells of various fresh-water molluscs. The fragments of stick and the small bits of gravel are held together by a kind of cement which the larva spins from his mouth. Sometimes we may meet with cases made of sand, having on either side long slender bits of rush or stick. A lady once took a number of the larvae out of their cases, and placed them in a vessel of water with various materials, such as coloured glass, cornelian, agate, onyx, brass filings, coralline, tortoiseshell; and these little maggoty things made use of and built their houses out of them. The perfect insect has four wings; and from these being closely covered with hairs, the order to which they belong has received the name of _Trichoptera_, which means "having hairy wings." You must know many of these insects; they are very common near ponds and streams; generally they fly in a zig-zag fashion, and have the appearance of moths. [Illustration: _a, b, c, d._ Larva, cocoon, nympha, and insect of Caddis-fly.] Ah! here is a splendid bed of the forget-me-not growing on this bank near the stream. Look at the blue enamel-like flowers, each with a yellow centre-eye; the leaves are bright green and rather rough. There are other species very much resembling this one you may often see in hedgerows and fields; but they are generally smaller plants; this one is the true forget-me-not. There are several stories about the origin of the name. Here is one:--Many years ago, a lady and knight were wandering by a river; the lady espied these bright blue flowers, on a small islet I suppose, in the deep river, and wished to possess them. Her lover immediately plunged in and plucked the plants, but the strength of the stream was too much for him on his return. With a great effort, however, he threw the flowers on the bank, exclaiming "Forget-me-not," and sank! "But the lady fair of the knight so true Still remember'd his hapless lot; And she cherish'd the flower of brilliant hue And she braided her hair with the blossoms blue, And she call'd it 'Forget-me-not.'"