Experiments to determine the Influence of Moisture on a Growing Root.--The objection might well be interposed that possibly the roots in the pocket garden[8] grew downward after water. That moisture has an influence on the growing root is easily proved. Footnote 8: _The Pocket Garden._--A very convenient form of pocket germinator may be made as follows. Obtain two cleaned four by five negatives (window glass will do); place one flat on the table and place on this half a dozen pieces of colored blotting paper cut to a size a little less than the glass. Now cut four thin strips of wood to fit on the glass just outside of the paper. Next moisten the blotter, place on it some well-soaked radish, mustard seeds or barley grains, and cover with the other glass. The whole box thus made should be bound together with bicycle tape. Seeds will germinate in this box and with care may live for two weeks or more. Plant bird seed, mustard or radish seed in the underside of a sponge, which should be kept wet, and may be suspended by a string under a bell jar in the schoolroom window. Note whether the roots leave the sponge to grow downward, or if the moisture in the sponge is sufficient to counterbalance the force of gravity. Water a Factor which determines the Course taken by Roots.--_Water, as well as the force of gravity, has much to do with the direction taken by roots._ Water is always found below the surface of the ground, but sometimes at a great depth. Most trees, and all grasses, have a greater area of surface exposed by the roots than by the branches. The roots of alfalfa, a cloverlike plant used for hay in the Western states, often penetrate the soil after water for a distance of ten to twenty feet below the surface of the ground.