Elements of biology; a practical Elements of biology; a practical text-book correlating botany, zoology, and human physiology elementsofbiolog00hunt Year: [c1907] 84 BOTANY Another experiment is the following: Divide the interior of a shallow wooden box into two parts by an incomplete partition. Partly fill the box with sawdust and place the opening in the partition so that it is below the surface of the sawdust. Plant peas and beans in the sawdust on one side of the partition, water very slightly, but keep the other side of the box well soaked. After two weeks, take up some of the seedlings
Elements of biology; a practical Elements of biology; a practical text-book correlating botany, zoology, and human physiology elementsofbiolog00hunt Year: [c1907] 84 BOTANY Another experiment is the following: Divide the interior of a shallow wooden box into two parts by an incomplete partition. Partly fill the box with sawdust and place the opening in the partition so that it is below the surface of the sawdust. Plant peas and beans in the sawdust on one side of the partition, water very slightly, but keep the other side of the box well soaked. After two weeks, take up some of the seedlings and note the efifect on the roots. Water a Factor which determines the Course taken by Roots.— Water, as i^ell as the force of gravity, has much to do with the direction taken by roots. The smaller roots, especially, are influ- enced by moisture. Mois- ture also determines the kind and abundance of roots on a plant. Water is always found below the surface of the ground, but some- times at a great depth. In order to obtain a sup- ply of water, the roots of plants frequently spread out for very great dis- tances. Most trees, and all grasses, have a greater area of surface exposed by the roots than by the branches. The mesquite bush, a low-growing tree of the American and Mexi- can deserts, often sends roots downwards for a distance of forty feet after water. The dandelion shown in the cut has a greater depth below the surface of the ground than appears above the surface. The roots of alfalfa, a common plant used for hay in the Western states, often penetrate the soil to a distance of ten to twenty feet below the surface of the ground. The force of gravity is an exciting cause or stimulus to the growth of plants. The reaction of the plant (or any living thing) to this force is called geotropism. Roots are stimulated by Dandelion plant. Photographed by Overton.
Size: 1208px × 1656px
Photo credit: © Bookworm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: archive, book, drawing, historical, history, illustration, image, page, picture, print, reference, vintage
