That is exactly what she would do. She would melt, or dissolve as we say, this sugar in water. Then there would be no difficulty in its slipping down the little throat; for you know when anything is thoroughly melted or dissolved, it breaks up into such tiny pieces that the eye cannot see them. When you melt a lump of sugar in a glass of water, the sugar is all there as much as it ever was, although its little grains no longer cling together in one big lump. And so when the plant needs some food that the little root hairs are not able to swallow, it does just what the mother does. It melts or dissolves the solid food so that this is able to slip quite easily down the root throats. But how does it manage this? No wonder you ask. A root cannot fill a glass with water, as your mother did. Even if it could, much of this solid food which is needed by the plant would not melt in water, or in anything but certain acids; for you know that not everything will dissolve, like sugar, in water. If I place a copper cent in a glass of water, it will remain a copper cent, will it not? But if I go into a drug shop and buy a certain acid, and place in this the copper cent, it will dissolve almost immediately; that is, it will break up into so many tiny pieces that you will no longer see anything that looks at all like a cent. And as much of this earth food, like the copper cent, can only be dissolved in certain acids, how is the plant to obtain them? Certainly it is not able to go to the drug shop for the purpose, any more than it was able to fill a glass with water. Fortunately it does not need to do either of these things. If you will look closely at the root of a plant that has been raised in water, you will see that it is rough with a quantity of tiny hairs. These little hairs hold the acid which can dissolve the solid earth food. When they touch this food, they send out some of the acid, and in this it is soon dissolved. Then the little mouths suck it in, and it is carried up through the root into the rest of the plant. Would you have guessed that plants were able to prepare their food in any such wonderful way as this? It surprised me very much, I remember, to learn that a root could give out acids, and so dissolve the earth food it needed. [Illustration: Decoration] ROOTS AND UNDERGROUND STEMS In the last chapter you learned that the root of the bean plant has two uses. It holds the plant in place, and it provides it with food and drink. Such a root as this of the bean plant—one that is made up of what looks like a bunch of threads—is called a “fibrous” root. The next picture shows you the root of a beet plant (Fig. 109). Such a thick, fat root as this of the beet is called a “fleshy” root. The carrot, turnip, radish, and sweet potato, all have fleshy roots. This beet root, like that of the bean, is useful both in holding the plant in place and in providing it with food and drink.