CHAPTER XXXII 

 CONTENTS AND PRODUCTS OF CELLS 



394. THE LIVING CELL IS A LABORATORY. In nearly all 

 cells are found one or more non- protoplasmic substances 

 which are produced by the plant. Some of these are very 

 useful to the plant, and others seem to be discarded or 

 excretory products. There is considerable division of labor 

 among the cells of higher plants, one cell or group of cells 

 producing one product and another cell producing another 

 product. 



395. CHLOROPHYLL. Cells may contain chlorophyll 

 bodies if they are exposed to the sunlight. Chlorophyll 

 is a green substance infiltrated in a protoplasmic ground - 

 mass. It imparts color to all the green parts of the plant. 

 Its presence is absolutely necessary in all plants which have 

 to secure their nourishment wholly or in part from the air 

 and from mineral matter of soil. Review Chapter XII. 

 Most parasites and saprophytes do not bear chlorophyll, 

 but live on organic matter (Chapter XIII). The oval 

 bodies in the cell of Figs. 411, 413, 414, are chlorophyll 

 bodies. 



396. CELL-SAP. Often the most abundant of the differ- 

 ent cell -contents is cell-sap. It may contain a number of 

 different substances, many of which are in solution and can 

 be detected by the use of chemical reagents. Some of these 

 substances are: 



milk (lactose). 



grape (glucose or dextrose, C 



Sugar, 



fruit (levulose). 



cane (saccharose, Ci2H 2 20n). 



malt (maltose). 



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