The children thought it lovely, and were proud of it. And the clock did for them what the grandfather wished,--it made them like and notice plants. I have just said that there are plants which open only by night, and others which open only by day. This opening and shutting for day and night is called “the sleep of plants.” This sleep of plants is not because the plant is tired; it is due to the absence or presence of light, and to changes in the amount of light. Yet, no doubt, in it the organs of the plant do rest, as their growth and action are not then so rapid. Both the flowers and the leaves of plants have this sleep motion. We will look first at the sleep of flowers. You have noticed that the morning-glories are open when you rise, and that they fold or shut up by noon. Have you in your garden a flower with gay yellow or scarlet blossoms, called the four-o’clock? That does not open until about four in the afternoon. As you run to school in the morning, the dandelions are gay along the way-side. When you come from school in the afternoon, the dandelions are all folded in their green cups. If this is so, why does not the flower-clock tell true time? You can see that owing to the changes in the heat and rising of the sun in different places, and seasons, the sleep of the flowers would not begin at the same time. I have seen my morning-glories open as late as nine o’clock, and stay open all day in cool October days. In August they opened by six and were shut by eleven. So the four-o’clocks and dandelions may vary by an hour or two. All the water-lilies shut at night. Some not only shut, but draw their heads down under water. I will tell you when you will find some flowers opening. At four in the morning you will find the goat’s-beard and the blue chicory opening. The chicory petals are then a fine blue. They become lighter in color until near mid-day, when they are almost white. Chicory is called “Miss-go-to-bed-at-noon” by some children, as the flowers shut at noon. At five in the morning the common morning-glory and the poppy open. At six the yellow hawk’s-weed and dandelions look out on the way-side. At seven the water-lilies smile at us. At eight, if the day is fine, the pimpernel opens its red eyes. At nine the marigold spreads out, and the tulip. At noon, on a hot day, you will find the tulip opened nearly flat. At eleven the Star of Bethlehem shuts up, while most of the day flowers are in their best bloom. At twelve the lazy passion-flowers awake, and the sweet-peas have their banners opened wide. At two the wild daisies are brightest. Then at four in the afternoon, out comes the four-o’clocks, and at five the “beauty of the night,” and at six the delicate evening primrose. At seven the white lychnis, which blooms only at night, opens. Later still the night primrose puts out its white bloom, and at two o’clock in the morning the purple convolvulus wakes up and wonders why the sun is so late.