CHAPTER IX 
CELL CONTENTS 
The cell contents of the plant are divided into two groups: 
first, organic cell contents; and secondly, inorganic cell contents. 
The organic cell contents include plastids, starch grains, 
mucilage, inulin, sugar, hesperidin, alkaloids, glucocides, tannin, 
resin, and oils. 
CHLOROPHYLL 
The chloroplasts of the higher plants are green, and they 
vary somewhat in size, but they have a similar structure and 
form. 
Chloroplasts are mostly oval in longitudinal view and rounded 
in cross-section view. Each chlorophyll grain has an extremely 
thin outer wall, which encloses the protoplasmic substance, the 
green granules, a green pigment (chlorophyll), and a yellow 
pigment (xanthophyll). Frequently the wall includes starch, 
oil drops, and protein crystals. 
Chloroplasts are arranged either in a regular peripheral 
manner along the walls, or they are diffused throughout the 
protoplast. 
The palisade cells of most leaves are packed with chlorophyll 
grains. In the mesophyll cells the chlorophyll grains are not 
so numerous, and they are arranged peripherally around the 
innermost part of the wall. 
Chloroplasts multiply by fission—that is, each chloroplast 
divides into two equal halves, each of which develops into a 
normal chloroplast. 
Chlorophyll occurs in the palisade, spongy parenchyma, and 
guard cells of the leaf; in the collenchyma and parenchyma of 
the cortex of the stems of herbs and of young woody stems, and, 
under certain conditions, in rhizomes and roots exposed to 
light. Almost without exception young seeds and fruits have 
chlorophyll. 
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