How crops growA treatise on the chemical composition, structure, and life of the plant, for all students of agriculture .. . In flg: 56 is represented a section throngli tlie shorter diameter of apore on the under surface of a bean-leaf. The air-space within it isshaded hlaclc. Unlike the other epidermal cells, those of the leaf-porecontain grains of chlorophyll. Fig. 57 represents a portion of the epidermis of the upper surface ofa potato-leaf, and fig. 58 a similar portion of the under surface of the sameleaf, magnified 200 diameters. In hoth figures are seen the open poresbetween the semi-e
How crops growA treatise on the chemical composition, structure, and life of the plant, for all students of agriculture .. . In flg: 56 is represented a section throngli tlie shorter diameter of apore on the under surface of a bean-leaf. The air-space within it isshaded hlaclc. Unlike the other epidermal cells, those of the leaf-porecontain grains of chlorophyll. Fig. 57 represents a portion of the epidermis of the upper surface ofa potato-leaf, and fig. 58 a similar portion of the under surface of the sameleaf, magnified 200 diameters. In hoth figures are seen the open poresbetween the semi-elliptical cells. The outline of the other epidermalcells is marked by irregular double round bodies in the cells of thepores are starch-grains, ofteu presentin these cells, when not existing in anyother part of the leaf. The stomata are with few ex-ceptions altogether wanting onthe submerged leaves of aquaticplants. On floating leaves theyoccur, but only on the uppersurface. Thus, as a rule, theyare not found in contact with liquid water. On the otherhand, they are either absent from, or comparatively few in. THE VEGETATIVE OEGANS OF PLAUTS. 287 nuniber upon, the upper surfaces of land plants, which areexposed to the heat of the sun, while they exist in greatnumbers on the Jower sides of all green leaves. In numberand size, they vary remarkably. Some leaves possess but800 to the square inch, while others have as many as170,000 to that amount of surface. About 100,000 maybe counted on an average-sized apple-leaf. In general,they are largest and most numerous on plants which be-long in damp and shaded situations, and then exist onboth sides of the leaf. The epidermis itself is most dense—consists of thick-walled cells and several layers of them—in case of leaveswhich belong to the vegetation of sandy soUs in hot cli-mates. Often it is impregnated with wax on its uppersurface, and is thereby made almost impenetrable to moist-ure. On the other hand, in rapidly growing
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectagricul, bookyear1868
