. Elementary botany. Botany. 44 PHYSIOLOGY. 97. We thus see that instead of the liquids passing through the entire stem they are confined to definite courses. Now that we have discovered the path of the upward movement of water in the stem, we are curious to see what the structure of these definite portions of the stem is. 98. Structure of the fibro-vascular bundles.—We should now make quite thin cross sections, either free hand and mount in water for microscopic examination, or they may be made with a microtome and mounted in Canada balsam, and in this condition will answer for future stud}'.
. Elementary botany. Botany. 44 PHYSIOLOGY. 97. We thus see that instead of the liquids passing through the entire stem they are confined to definite courses. Now that we have discovered the path of the upward movement of water in the stem, we are curious to see what the structure of these definite portions of the stem is. 98. Structure of the fibro-vascular bundles.—We should now make quite thin cross sections, either free hand and mount in water for microscopic examination, or they may be made with a microtome and mounted in Canada balsam, and in this condition will answer for future stud}'. To illustrate the structure of the bundk- in one type we may take the stem of the castor-oil bran. ()n examining these cross sections we see that there are groups of cells which are denser than the ground tissue. These groups correspond to the colored areas in tin- former experiments, and are the vascular bundles. Fig. 41. \vliin portion ol bundle Cambium portion ol bundle. Bast portion of bundle Set lion t vascular bundle t sunflower stem. Cut across. These groups are somewhat oval in outline, with the pointed end directed toward the center of the stem. If we look at the section as a whole we will see that there i-> a narrow continuous ring* of -mall cells !: This ring and the bundles separate the stem into two regions, an outer one composed l large cells with thin walls, known as the cortical cells, or collectively the cortex. The inner portion, corresponding to what is called the pith, i- made up «»l the same kind oi cells and i- called the medulla, or pith. When the cells of tin- cortex, as well a- of the pith, remain thin walled the tissue i- called parenchyma. Parenchyma belongs to the group oi tissues i ailed fund a Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Atkinson, George Fran
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