The empty space in the cytoplasm of the cell is called vacuole. The membrane of the cell cavity is called tonoplast. Tonoplast is a rubbery material. In plant cells, several small cavities combine to form larger cavities. It has no specific shape or size. It is filled with tissue. Cells contain water, inorganic salts, organic acids, meat, sugars, fats, various types of dyes, etc.