CELL-CONTENTS. STAKCH. 



423 



forming a similar office in the economy of plants as that of fat in ani- 

 mals. It occurs in all plants at some period of their existence, and is 

 the chief and great mark of distinction between the vegetable and ani- 

 mal kingdoms. Its presence is detected by testing with a solution of 



fig. 203. 



1. Portion of the husk of Wheat, showing siliceous crystals. 2. Siliceous cuticle of 

 blade of Grass (Pha.rus cristatus). 3. Siliceous cuticle from under surface of leaf of 

 Deutzia scahia. 4. Section of a Cane ; the cell-walls of silica, and internal pores 

 filled with granular matter. 



iodine, which changes it to a characteristic blue or violet colour. Being 

 insoluble in cold water, it can be readily washed away and separated 

 from other matters contained in the cellular parts of full-grown plants. 

 It is often found in small granular masses in the interior of cells, 



