. Plant anatomy from the standpoint of the development and functions of the tissues, and handbook of micro-technic. Plant anatomy. THE ROOT HAIRS 91. Fig. 42.—Cross section of a root in the region of the root hairs. without being shoved and jammed forward as would be the case if elongation were kept up in the remoter parts. Under average conditions the water in the soil exists as a thin film around each soil particle and holds in dilute solution ( per cent, to per cent.) some of the con- stituents of the particles that are necessary to plants. To get the water and solutes it is obviou
. Plant anatomy from the standpoint of the development and functions of the tissues, and handbook of micro-technic. Plant anatomy. THE ROOT HAIRS 91. Fig. 42.—Cross section of a root in the region of the root hairs. without being shoved and jammed forward as would be the case if elongation were kept up in the remoter parts. Under average conditions the water in the soil exists as a thin film around each soil particle and holds in dilute solution ( per cent, to per cent.) some of the con- stituents of the particles that are necessary to plants. To get the water and solutes it is obviously necessary that many fine outgrowths from .the root should reach out on all sides, and, pressing them- selves against the soil particles, become immersed in the films of water. The Root Hairs.—The root elongates close to its apex, and 2 or 3 mm. back from this it ceases to grow in length, and some of the epidermal cells here grow out in the form of slender tubes known as root hairs (Fig. 42). So far as recorded. measure- ments show these may become from a fraction of a millimeter to 8 millimeters in length. Growing only at its point a root hair reaches out through the humid atmosphere of the soil interspaces until it strikes a solid particle, when it bends about this and flattens out over it to a certain extent (Fig. 43). At the place of contact the delicate cellulose wall of the hair becomes somewhat mucilaginous and is thus all the better able to cling on and imbibe water, and when it reaches a soil particle and becomes fastened to it this contact seems to act as a stimulus to stop its further growth in length. By means of the root hairs the roots are able not only to make close contact with soil and soil water, but they also increase their absorbing surface many times—from five to twelve times ac-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrati
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectplantanatomy, bookyea
