. Plants; a text-book of botany. Botany. Fig. 32. Section tlirough a portion of the leaf of the yew {Taxus)^ showing cuticle (c), epidermis (e), and the upper portion of the palisade cells (p). form two or three layers, we might infer the probability of exposure to intense light or drought. The accompanying illustration (Fig. 31) shows in a striking way the effect of light intensity upon the structure of the mesophyll, by contrasting leaves of the same plant exposed to the extreme conditions of light and shade. The most usual structural adaptations, however, are connected with the epidermis. T
. Plants; a text-book of botany. Botany. Fig. 32. Section tlirough a portion of the leaf of the yew {Taxus)^ showing cuticle (c), epidermis (e), and the upper portion of the palisade cells (p). form two or three layers, we might infer the probability of exposure to intense light or drought. The accompanying illustration (Fig. 31) shows in a striking way the effect of light intensity upon the structure of the mesophyll, by contrasting leaves of the same plant exposed to the extreme conditions of light and shade. The most usual structural adaptations, however, are connected with the epidermis. Tlio outer walls of the epi- dermal cells may Ijccome thickened, sometimes excessively so; the other epidermal .-_ ^^^ walls may (j become more or less thickened; or even what seems to be more than one epi- dermal layer is found protecting the meso- phyll. If the outer walls of the epidermal cells continue to thicken, the outer re- gion of the thick wall loses its structure and forms the culide. which is one of the. Fig. 33. Section through a portion of the leaf of carnation, showing the heavy cuticle (cw) formed by the outer whIIk of the epidermal cells iep). Through the cuticle a passageway leads to the stoma, whose two guard-cells are seen lying hitHccn the two epidermal cells shown in the figure. Below the epidermal cells some of the jjalisade cells {pat) are shown containing chloroplasts, and helow the stoma is seen the air chamber into which it 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 Coulter, John Merle, 1851-1928. New York, D. Appleton and company
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