Now, in sleeping, most of the flowers close tight together. Besides the rest to the growing organs, which sleep brings them, this folding up keeps moisture from the pollen. Also, the flowers, whose partners are day-flying insects, keep out of the way of night insects by closing their pretty doors. The evening primroses, night lychnis, and others, which have night-flying insect partners, keep shut when day insects are about. You will notice that most of these night plants have yellow or white petals, and a sweet perfume. I have told you the leaves sleep also. Leaves sometimes sleep by closing the two halves of the leaf together by the mid-vein. Other leaves sleep by dropping the leaves down against the stem. A young Swiss girl was one of the first to observe this sleep motion of leaves. She saw it first in the clover. When the leaves sleep in this way, you might think them faded and dying. You will do well to watch this sleep of leaves. If you go into a garden, or field, or on the road-side, you will see that the leaves look very different after sunset from what they did in the noon-day. The yellow sorrel and the clover are plants in which you can watch leaf-sleep well. You will find the small leaflets hanging down against the stalk. So if you look at the beans in the garden, you will see their leaves falling back, and perhaps a little bent over. One kind of oxalis, with very small, compound leaves, lifts its leaves up all in a bunch to go to sleep. The leaves of trees have sleep-change. The mimosa and the barberry close their leaves at night. Are these sleep motions of any use to plants? Yes. It has been found that this folding up, and falling back of leaves, will help them to resist cold and wet. If, during a cold night, you pin the leaves out, so they cannot take the sleep position, they are likely to freeze. Also this change in the leaves, at night, helps to shield the plant from too much dew. Sometimes, also, it is of use as it turns toward the dew the under side of the leaf. This under side has the most mouths for drinking water. Thus the flower has a good drink at night, after the dry, hot day. Among the other motions of plants, I might speak of that of some leaves, which curl or shrink if you touch them. But I have not space for that now. Perhaps you think that these lessons have told you a great many things about flowers. If you go on with the study of plants, you will see how much there is to tell, and how very little has here been told. These lessons are only meant to stir up your interest in plants, and show you what wonders are in the plant world. After that, you will be sure to learn more for yourselves. LESSON XV. THE SCHOOL CABINET.