THE SLEEP OF TEE TREES.
Trees are, after all, very much like folks! sleep o' nights, they feed and drink, and thereby grow. They breathe through a kind of lungs the same life-giving oxygen, and throw off carbon dioxid. They tear their clothes, and have to mend them. In a crowd, they jostle each other, like rude boys, and the big fellows usually conquer the weaker ones. They get cuts and bruises and broken limbs; and there is a long catalogue of tree diseases, most of them catching, like the measles and the whooping-cough.
In winter, trees put on their warmest coats—a fashion set by the woodchuck and the bear—and just sleep and wait for spring! In warm weather a tree goes to sleep at sundown, and wakes up in the morning. If the sky is overcast, the tree is drowsy; if rain sets in, it goes right off to sleep. The only days that really count in a tree's calendar are the clear ones.
Have you ever seen a tree asleep? Near my house are a number of locusts growing. Their fern-like leaves are held in sweeping, graceful clusters up into the sunshine. But on wet days, and all through the night, those leafy twigs droop down listlessly; the leaflets fold their palms together; the whole tree is the picture of limp helplessness. It is the locust's way.
closing of the leaflets reduces evaporation (which is a cooling process), and enables the tree to save much of its bodily heat. For a similar reason a kitten tucks its feet snugly under its body, and curls its tail around, before it takes a nap. All young and tender foliage tends thus to `• cuddle down when it is sleepy. But older and stiffer leaves can sleep sitting erect, as grown-up folks will often do.
Let me suggest thlt you select an elm or a maple near by, or any other tree, and watch tit. Compare the night and day positions of the leaves when just opening. As they become full grown, continue your observations and comparisons. Better confine yourself to one special twig of each tree. Take np a thrifty young plant of white clover from the lawn. Get it well started in a pot. Then watch it as its
leaves change at night and in the morning. It is one of the most interesting things you can have about you. Set it in a dark closet for a while in the middle of the day. Let others enjoy these little experiments with you.
Day and night. rain or shine, trees keep breathing as steadily as you do. Should you stop you would smother and die. Just as soon and just as truly would the trees. No creature lives hut needs to breathe; that is the process that keeps the living tissues in working order The constant tearing down and building up of cells is the one condition upon which life exists. In order that there may always be nutri tion at hand to rebuild the cells, and that the tree may grow in stature and strength from year to year, food must be taken in, elaborated. and stored away. it is to serve this end that the tree wakes from its winter sleep. It is for this that it rests by night and wakes so early in the morning.
Every leaf that spreads its broad, green blade into the sunshine is a laboratory devoted to the manufacture of starch. The raw materials are obtained from the air, and from the soil. The machinery is the soft green leaf-pulp. The sun furnishes the power. When the sun is gone, the starch factory shuts down. After dark there is clearing up to be done, and nutting of things away. t is not an things - - - --eight-hour day: work stretches from sun to sun. But there is no —night shift in the starch works of a. tree or of any other plant.
It is a surprise to many people to learn how short is the tree's grow ing season. By midsummer the twigs are usually as long as they are going to be. The ring of new WOod is formed around the trunk. The tree begins to get ready for winter. Now this long winter vaca tion is not indicative of an inliorn tendency toward idleness in any species of trees. It is rather a habit acquired by nearly all of them, a concession to the demands of our rigorous climate. The problem is more essentially one of water supply than of temperature.