. Botany of the southern states. In two parts. Botany. LEAVES. 47 the pores are more equally distributed on both surfaces, as in the Iris. Those leaves which lie upon the water have no pores on the under surface ; the upper surface performing the func- tions usually belonging to the under side. 84. The parenchyma appears to the unassisted eye a mass of irregularly arranged cells ; but by careful examination, aided by the microscope, Ave find a remarkable regularity in the arrangement of the cells. It^we take a thin slice, made by a vertical section, of the leaf of an Apple or Peach, and observ
. Botany of the southern states. In two parts. Botany. LEAVES. 47 the pores are more equally distributed on both surfaces, as in the Iris. Those leaves which lie upon the water have no pores on the under surface ; the upper surface performing the func- tions usually belonging to the under side. 84. The parenchyma appears to the unassisted eye a mass of irregularly arranged cells ; but by careful examination, aided by the microscope, Ave find a remarkable regularity in the arrangement of the cells. It^we take a thin slice, made by a vertical section, of the leaf of an Apple or Peach, and observe it by a good magnifier, wTe shall find imme- Fig 39 diately beneath the cuticle, which consists of a single row of cells, two or three layers of cylin- drical cells arranged perpendicularly to the sur- face, with very small intercellular cavities. Be- tween them and the under surface are four or five rows of similar cells, but differently arranged, touching each other by their ends, and lying in- clined to the surface of the leaf, forming com- paratively large cavities, particularly immediately beneath the stomata. Fig. 39 exhibits a type of the arrangement of dicotyledons; that side of the leaf which is furnished with stomata being cavernous, and the opposite side more compact. Those leaves which have the stomata equally distributed on both surfaces, and those also which have no stomata, have cells of the parenchyma of the two surfaces similarly arranged. 85. The veins of the leaf, which ramify in every direction through the parenchyma, are composed of vessels inclosed by a sheath of woody fiber. These veins serve two purposes, that of giving form and support to the parenchyma, and affording channels for the circulation of the sap to the various parts of the leaf, and returning it to the stem. The veins are largest where they enter the leaf, and decrease as they proceed and ramify, till they are lost to our observation in the cellular tissue. There are two separate venous sy
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1885
