Jack jumped down from his pulpit. “That will do, attendants,” he said. “Thank you,” and the little elves ran away. “We have here,” he continued, “a fairy view of the way in which plants grow. Come, Bet!” With that, both the little fairies sprang to the top of the tub, and a wonderful thing happened. The tub and the tree began to grow so fast that before you could count three, they were as high as the girls’ knees, and before you could count seven, the top of the tree was even with Eleanor’s head. “That’s tall enough, tree,” cried Jack, and both tub and tree stopped growing. “Can you see, young ladies,” he asked as he bent over the side; “can you see the roots of the magic tree through the glass?” The girls could see them plainly. “Did you notice how they pushed their way through the stones and pieces of rock, and even moved them as they grew!” “I did!” answered each of the girls. “I thought it wonderful,” continued Mary Frances, “but I supposed it was a fairy way of growing.” “No,” Jack shook his head; “that is the way all plants grow, whether small or large, only they grow slowly. Notice the smallest roots. They are hollow and have very thin delicate coverings.” “You will see why in a minute,” he went on, “but now I wish to call your attention to something else. In between the stones and sand you will notice decaying leaves and——” “Humus!” cried Mary Frances jumping up in excitement. “Good!” he said. “Humus soup is what the plants eat. The tiny roots draw it up through their thin walls. In the humus soup is not only decaying vegetable matter, but very tiny bits of mineral matter, too—like pepper and salt for the plant, maybe.” The girls laughed. “Listen!” he went on earnestly; “for any plant to produce one pound of dry matter, the roots must take up from 300 to 500 pounds of water.” “Oh, now, I see why plants must have water,” said Mary Frances. “Now, I understand why it is so necessary to cultivate—to hold the moisture in the ground.” “To make humus soup,” Eleanor added. “Fine!” cried Jack, rubbing his tiny hands in glee. “It’s splendid to teach such interested persons. It took human beings many, many years to find these things out. If only their eyes and ears had been open to us fairy folks, it wouldn’t have taken so long.” “Now, human people, in growing garden plants, want to give them the best kinds of food,” he continued. “So, after studying to find out what is in the soil that plants need most, they have gathered those things together from various places, and have made Commercial Fertilizers. “They are to be had in a powdered form, and are very concentrated plant food. Nothing is better to use, however, than barnyard manures.” “One of the best commercial fertilizers is Nitrate of Soda.” (See Chapter LVIII entitled, “Some Hints on Growing Vegetables.”) CHAPTER XLIII HOW PLANTS GROW “WHAT becomes, please, of the humus soup after the plant roots take it up?” asked Mary Frances thoughtfully.