. Fundamentals of botany. Botany. LOSS OF WATER 37 seven bundles extends out into the blade as the prominent mid-vein of a leaflet. In a common "trick" of child- hood, the epidermis of the petiole of the common, broad- leaved plantain is broken by sharply bending the petiole, or by carefully cutting with a knife. The petiole may then be carefully pulled apart, so as to dis- close the fibro-vascular bundles without breaking them (Fig. 29). These bundles are the channels through which liquids pass between the leaf-blade and the branch. 38. Transpiration.—In order to understand transpir
. Fundamentals of botany. Botany. LOSS OF WATER 37 seven bundles extends out into the blade as the prominent mid-vein of a leaflet. In a common "trick" of child- hood, the epidermis of the petiole of the common, broad- leaved plantain is broken by sharply bending the petiole, or by carefully cutting with a knife. The petiole may then be carefully pulled apart, so as to dis- close the fibro-vascular bundles without breaking them (Fig. 29). These bundles are the channels through which liquids pass between the leaf-blade and the branch. 38. Transpiration.—In order to understand transpiration, we should have in mind a clear pic- ture of the conditions within a leaf.^ Because of moisture in the cells, the cell-walls are saturated. From their moist surfaces water is continually evaporating into the intercellular spaces (Fig. 27), so that the air in those spaces is al- ways nearly saturated; that is, it holds nearly as much water as pos- sible in the form of vapor. From the intercellular spaces the vapor diffuses out through the stomata, and passes off into the air. If the outer air is also very humid, as frequently near the ground after sunset, the. Fig. 29.—^Leaf of plantain (Plantago), with the petiole stretched lengthwise from a transverse cut, showing the fibro-vascular bundles that continue up Into the five main veins of the leaf-blade. (Photo by the author.) I While loss of water is not confined to leaves, they are the chief organs of transpiration, and if we understand the process in them, we shall understand 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 Gager, C. Stuart (Charles Stuart), 1872-1943. Philadelphia, P. Blakiston's son & co.
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Keywords: ., bookauthorgag, bookcentury1900, bookdecade1910, booksubjectbotany
