the whole plant; it is therefore of stronger and tougher material than the branches and leaves which it has to carry and lift above the ground into the air. To do their work properly the leaves need holding in a particular position; the stem and its branches do this for them, besides carrying the flowers and the seeds of the plant as the season advances.

7. A great tree with wide-spreading branches needs a stem thick and stout, in order to withstand the pressure of high winds, and to support its weight of leaves in summer, or the mass of snow which may weigh upon it in winter. Annuals need only soft and tender stems, because at the end of the season they wither and die away.

8. Some stems, like those of the kidney bean and the hop plant, climb upwards by twining their stems around supports. Ivy stems send out rootlets which will fasten themselves on to walls or wood, or anything else upon which they can manage to cling. The pea will cling to any object it can reach by means of its stringy stems called tendrils. Brambles climb by the help of those hooked thorns which grow along their stems.

SECTION ACROSS TRUNK OF OAK, SHOWING (a) BARK; (b) RINGS; (c) PITH, OR HEARTWOOD.

necessary for the growth of the young plant, but in the old tree it is no longer needed. In the oak and other large trees it is a mere thread.

2. If the trunk or stem of a tree, such as the oak or the fir, be sawn across, a number of rings will be seen in the woody part. Each of these rings shows one year's growth of the tree, so that the age of the tree may be found by counting the rings.

3. The hardest part of the woody stem is that nearest the pith, because it is the oldest and the driest carpenters call it the heartwood. The softer layers outside are known as sapwood.

4. The bark of a tree is its outside layer; but the bark itself has an inner skin called bast, which is so stringy that gardeners split it into strips for tying up their plants. Between the bark and the white wood is a sticky layer; this is the part of the stem which is growing, and some of it will harden into wood fibers, some into bast fibers.

5. In the case of many trees the inside growth goes on until the bark can bear the strain no longer. It cracks in all directions and peels off. All trees which grow from seeds containing two seed-leaves shed their bark, and a renewal takes place where the old has peeled off.

6. The work of the bark is to keep the tree always at the same degree of warmth, for if the tree is to keep alive, its sap must pass freely along both in the heat of summer and in the depth of winter-it must never dry up or freeze. Bark

serves as a defensive armor, too, against such enemies of the tree as the woodpecker and the gnawing rabbit. Oak bark is made useful in tanning leather. Cork is but the bark of an oak which grows in Spain.

7. Canes and bamboos have no bark; but the hardest wood in them is on the outside. These plants are nothing more than giant grasses, and like the common grass they grow from seeds which contain one seed leaf.

8. Some trees contain juices which run out, and then dry solid in the form of gums and resins. Gutta-percha is the juice of a tall tree that grows in Asia, and india rubber is another dried, milky juice of certain trees which grow in warm climates. Turpentine is obtained from pine trees.

9. Among hardwood timbers the oak is one of the best. The walnut, chestnut, beech and ash are also valuable timber trees. Pine, hemlock and cedar are the most valuable evergreens. Mahogany is a fine timber from tropical America.