. Foundations of botany. Botany; Botany. MINUTE STRUCTURE OF LEAVES 157 to soak through it with ease. Merely examining sections of the various kinds of epidermis will not give nearly as good an idea of their properties as can be obtained by studying the behavior during severe droughts of plants which have strongly cutinized surfaces and of those which have not. Fig. 121, however, may convey some, notion of the difference between the two kinds of structure. In most cases, as in the india- rubber tree, the ex- ternal epidermal cells (and often two or three layers of cells beneath these) are =^::
. Foundations of botany. Botany; Botany. MINUTE STRUCTURE OF LEAVES 157 to soak through it with ease. Merely examining sections of the various kinds of epidermis will not give nearly as good an idea of their properties as can be obtained by studying the behavior during severe droughts of plants which have strongly cutinized surfaces and of those which have not. Fig. 121, however, may convey some, notion of the difference between the two kinds of structure. In most cases, as in the india- rubber tree, the ex- ternal epidermal cells (and often two or three layers of cells beneath these) are =^::z:—"^n^^^" <:^, ^%, filled with water, and b 1C___JL J\^ a. Fig. 121. — Unequal Development of Cuticle by Epidermis-Cells, ^.'epidermis of Butolier's Broom (Rusous); B, epidermis of sunflower; c, cuticle; e, epi- dermis-cells. thus serve as reser- voirs from which the outer parts of the leaf and the stem are at times supplied. In many cases, noticeably in the cabbage, the epidermis is covered with a waxy coating, which doubtless increases the power of the leaf to retain needed moisture, and which certainly prevents rain or dew from covering the leaf-surfaces, especially the lower surfaces, so as to hinder the operation of the stomata. Many common plants, like the meadow rue and the nasturtium, possess this power to shed water to such a degree that the under surface of the leaf is hardly wet at all when immersed in water. The air-bubbles on such leaves give them a silvery appearance when held under 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
