THE CELL 17 



certain stains. The cytoplasm of many, possibly of all, 

 plant cells contains, scattered through it, numerous tiny, 

 deeply staining granules, called chondriosomes. 



(a) The cytoplasm appears net-like, or reticular, in 

 structure, and the spaces between the meshes are vacuoles. 

 Each vacuole is filled with an aqueous solution of various 



FIG. 9. Diagram of a plant cell in perspective, with portions of adja- 

 cent cells. Note the nucleus. The lighter areas are vacuoles in the 

 cytoplasm. 



substances, known as the cell-sap. Insoluble solids of 

 various nature, such as crystals and starch grains, com- 

 monly occur in the vacuoles. 



(b) At every free surface, such as the outer surface and 

 the walls of the vacuoles, the cytoplasm is specially organ- 

 ized into a limiting membrane (or plasma-membrane). 

 The structure of this membrane is not well understood, 



