. Foundations of botany. Botany; Botany. MrNTJTE STRUCTURE OF LEAVES 153 In the case of an apple tree, where the epidermis of the lower surface of the leaf contains about 24,000 stomata to the square inch, or the black walnut, with nearly 300,000 to the square inch, the total number on a tree is incon- ceivably large. 163. Uses of the Parts examined It will be most con- venient to discuss the uses of the parts of the leaf a little later, but it will make matters simpler to state at once that the epi- dermis serves as a mechanical protec- tion to the parts beneath and pre- vents excessive evapo
. Foundations of botany. Botany; Botany. MrNTJTE STRUCTURE OF LEAVES 153 In the case of an apple tree, where the epidermis of the lower surface of the leaf contains about 24,000 stomata to the square inch, or the black walnut, with nearly 300,000 to the square inch, the total number on a tree is incon- ceivably large. 163. Uses of the Parts examined It will be most con- venient to discuss the uses of the parts of the leaf a little later, but it will make matters simpler to state at once that the epi- dermis serves as a mechanical protec- tion to the parts beneath and pre- vents excessive evaporation, that the palisade-cells (which it may not be easy to make out very clearly in a roughly prepared section) hold large quantities of the green coloring matter of the leaf in a position where it can receive enough but not too much sunlight, and the. cells of the spongy parenchyma share the work of the palisade- cells, besides evaporating much water. The stomata admit air to the interior of the leaf (where the air spaces. Fig. 118. —A Stoma of Thyme. (Greatly magnified.) A, section at right angles to surface of leaf; B, sur- face Tiew of stoma, ou, cuticle ; g^ guard-cellfi; «, stoma ; £, epidermal cells; a, air chamber; tit cells of spongy parenchyma with grains of 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; Eastwood, Alice, 1859-1953. Boston, Ginn & Co.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1901
