How crops growA treatise on the chemical composition, structure, and life of the plant, for all students of agriculture .. . Fig. 38. outer cells of the root The older roots lose theirhairs, and suflfer a thickening ofthe outermost layer of cells bythe deposition of cork. Thesedense-walled and nearly imper-vious cells cohere together andconstitute a rind, which is notfound in th@ ypung and ftOtiveroots. As to the development ofthe poothairs, they are more. Kg. S9. THE VEGETATITE OEGAKS OF PLANTS. 245 abundant in poor than in good soils, and appear to bemost numerously produced from roots which
How crops growA treatise on the chemical composition, structure, and life of the plant, for all students of agriculture .. . Fig. 38. outer cells of the root The older roots lose theirhairs, and suflfer a thickening ofthe outermost layer of cells bythe deposition of cork. Thesedense-walled and nearly imper-vious cells cohere together andconstitute a rind, which is notfound in th@ ypung and ftOtiveroots. As to the development ofthe poothairs, they are more. Kg. S9. THE VEGETATITE OEGAKS OF PLANTS. 245 abundant in poor than in good soils, and appear to bemost numerously produced from roots which have other-wise a dense apd unabsorbent surface. The roots of thoseplants which are destitute of hairs are commonly of con-siderable thickness and remain white and of delicate tex-ture, preserving their absorbent power throughout thewhole time that the plant feeds from the soil, as is the casewith the onion. The Silver Fir, [Abies peetinafa,) has no root-hairs, butits rootlets are covered with a very delicate cuticle highlyfavorable to absorption. The want of root-hairs is furthercompensated by the great number of rootlets which areformed, and which, perishing mostly before they becomesuperficially indurated, are continually replaced by newones during the growing season. (Schaoht, Der Saum,p. 165.) ^ Contact of Roots with the Soil.—^The root-hairs, asthey extend into the soil, are natijrally brought into closecontact with its particles. This con
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectagricul, bookyear1868
