In parts of the South new sweet potato plants are obtained by cutting parts of the stems from growing plants and planting them. Florists produce large numbers of new plants by taking advantage of this function of stems. =Experiment.=--Take a white potato which is a thickened stem and place it in a warm, dark place. It will soon begin to sprout or send out new stems, and as these new stems grow the potato shrinks and shrivels up. Why is this? It is because the starch and other material stored in the potato are being used to feed the new branches. When we plant potatoes in the garden and field the new plants produced from the eyes of the potato are fed by the stored material until they strike root and are able to take care of themselves. All stems store food for the future use of the plant. Annual plants, or those which live but one year, store food in their stems and leaves during the early part of their growth. During the fruiting or seed forming season this food material is transferred to the seeds and there stored, and the stems become woody. This is a fact to bear in mind in connection with the harvesting of hay or other fodder crops. If we let the grass stand until the seeds form in the head, the stem and leaves send their nourishment to the seeds and become woody and of less value than if cut before the seeds are fully formed. In plants of more than one year's growth the stored food is used to give the plant a start the following season, or for seed production. The rapid growth of leaf and twig on trees and shrubs in spring is made from the food stored in the stem the season before. Sago is a form of starch stored in the stem of the sago palm for the future use of the plant. Maple sugar is made from the food material stored in the trunk of the maple tree for the rapid growth of twig and leaf in the spring. Cane sugar is the food stored in the sugar cane to produce new plants the next season. If we examine the stem of a tree that has been cut down we find that it is woody, that the wood is arranged in rings or layers and that the outer part of the stem is covered with bark. We will notice also that the wood near the centre of the tree is darker than the outer part. This inner part is called the heart wood of the tree. The lighter wood is called the sap wood. It is through the outer or sap wood that the water taken in by the root is passed up to the leaves where the food which it carries is digested and then sent back to the plant. The returning digested food is sent back largely through the bark. Between the bark and the wood is a very thin layer which is called cambium. This is the active growing tissue of the stem. In the spring it is very soft and slippery and causes the bark to peel off easily. This cambium builds a new ring of wood outside of the old wood and a new ring of bark on the inside of the bark. In this way the tree grows in diameter.