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 A grass plant pulled in a garden.

(Chaps. VII and VIII).—25. Tests for food. Examine a number of roots, including several fleshy roots, for the presence of food material, making the tests used on seeds. 26. Study of root-hairs. Carefully germinate radish, turnip, cabbage, or other seed, so that no delicate parts of the root will be injured. For this purpose, place a few seeds in packing-moss or in the folds of thick cloth or of blotting paper, being careful to keep them moist and warm. In a few days the seed has germinated, and the root has grown an inch or two long. Notice that, except at a distance of about a quarter of an inch behind the tip, the root is covered with minute hairs (Fig. 44). They are actually hairs; that is, root-hairs. Touch them and they collapse, they are so delicate. Dip one of the plants in water, and when removed the hairs are not to be seen. The water mats them together along the root and they are no longer evident. Root-hairs are usually destroyed when a plant is pulled out of the soil, be it done ever so carefully. They cling to the minute particles of soil (Fig. 46). The hairs show best against a dark background. 27. On some of the blotting papers, sprinkle sand; observe how the root-hairs cling to the grains. Observe how they are flattened when they come in contact with grains of sand. 28. Root hold of plant. The pupil should also study the root hold. Let him carefully pull up a plant. If a plant grow alongside a fence or other rigid object, he may test the root hold by securing a string to the plant, letting the string hang over the fence, and then adding weights to the string. Will a stake of similar size to the plant and extending no deeper in the ground have such firm hold on the soil? What holds the ball of earth in Fig. 50? 29. Roots exert pressure. Place a strong bulb of hyacinth or daffodil on firm-packed earth in a pot; cover the bulb nearly to the top with loose earth; place in a cool cellar; after some days