. Elements of botany. Plants. ROOTS. 31 (c) The woody cylinder which forms the central portion of the root. The distinction between (b) and (c) is more evident when the section has been exposed to the air for a few minutes and changed somewhat in color. It is a good plan to look with the low power first at a thick section, viewed as an opaque object, and then at a very thin one mounted in water or glycerine, and viewed as a transparent object. Observe the cut-off ends of the ducts, or vessels, which serve as pas- sages for air and water to travel through ; these appear as holes in the. w ' Fig
. Elements of botany. Plants. ROOTS. 31 (c) The woody cylinder which forms the central portion of the root. The distinction between (b) and (c) is more evident when the section has been exposed to the air for a few minutes and changed somewhat in color. It is a good plan to look with the low power first at a thick section, viewed as an opaque object, and then at a very thin one mounted in water or glycerine, and viewed as a transparent object. Observe the cut-off ends of the ducts, or vessels, which serve as pas- sages for air and water to travel through ; these appear as holes in the. w ' Fig. 19. —Magnified Cross-Section of a very Young Exogenous Root. w, root-hairs with bits of sand adhering ; r, parenchyma cells of the bark ; e, inner- most layer of the bark ; b, bast; h, vessels ; c, c', cambium. section, and are much more abundant relatively in the young than in the older and larger portions of the root. Sketch one section of each kind. Examine with a higher power (100 to 200 diameters), and note the ends of the thick-walled wood-cells. Compare these with Fig. 19. Notice the many thinner-walled cells composing stripes radiating away from the centre of the root. These bands are the medullary rays, whose mode of origin is shown in Fig. 52. Moisten some of the sections with iodine solution,i and note where the blue color shows the presence of starch. Split some portions of the root through the middle, cut thin 1 If the roots are in their Aviuter 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 Bergen, Joseph Y. (Joseph Young), 1851-1917; Bergen, Joseph Y. (Joseph Young), 1851-1917. Bergen's Botany: key and flora, Pacific coast ed. Boston : Ginn
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectplants, bookyear1896
