The induction, development, and heritability of fasciations . e the distal ends of the medullary rays and paren-chyma between them. There is nothing noteworthy in the present connec-tion regarding either pith or wood. 12 TOPOGRAPHY OF CHLOROPHYLL APPARATUS IN DESERT PLANTS. The chlorophyll band is made up of cuboid and elongated cells, of whichthe latter have the long: axis placed parallel to the surface of the stem. Inaddition to the outer chlorophyll band, chlorophyll is found sparingly inthe medullary rays both of the cortex and of the wood and in the pith also. With increase in diameter th
The induction, development, and heritability of fasciations . e the distal ends of the medullary rays and paren-chyma between them. There is nothing noteworthy in the present connec-tion regarding either pith or wood. 12 TOPOGRAPHY OF CHLOROPHYLL APPARATUS IN DESERT PLANTS. The chlorophyll band is made up of cuboid and elongated cells, of whichthe latter have the long: axis placed parallel to the surface of the stem. Inaddition to the outer chlorophyll band, chlorophyll is found sparingly inthe medullary rays both of the cortex and of the wood and in the pith also. With increase in diameter the stem exhibits certain changes in its generalstructure, of which the most important in the present connection are to befound in the cortex. Cork is org-anized early and is superficial. Thephelloderm is in direct contact with the chlorophyll band and probably con-tributes chloroi)hyll-bearing cells to the latter, although this was notdefinitely determined. The other changes in the cortex do not affect thedistribution of the chlorophyll and may be Fig. 5.—Covillea tridentata: A, transverse section of stem 5 mm. in diam-eter, showing character of spongy tissue of chlorophyll band; i?, transversesection of leaf, showing palisade character of subepidermal chlorenchyma;C, cross-section of stem i mm. in diameter, to show general distribution ofchlorophyll. Lettered as in fig. 3. The order of disappearance of chlorophyll from the stem was not a stem mm. in diameter chlorophyll was observed in the pith, in themedullary rays of wood and of cortex, and in the chlorophyll band. In astem 3 mm. in diameter, however, it had practically disappeared from alltissues deeper in the stem than the chlorophyll band; in a stem mm. indiameter no traces of chlorophyll were to be detected outside of this chlorophyll was found in another branch 2 cm. in diameter and 145 the tip, although the i:»rimitivc chloroph\-ll band, but without chloro-phyll, was .s
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