Fig 19-17. Section through a young leaf of F. chiloensis. A) stomata, B) air space, C) thick cuticle of upper leaf surface, D) upper epidermal cell, E) palisade cell, F) mesophyll cell. The interior cell surface exposed to air space is from 2.2 to 4.4 times greater than the exposed outer surface; in F. chiloensis it is about four times greater. Oxygen in the air enters through the stomata, comes in contact with the cell walls and enters the cells. Carbon dioxide and water are given off and go out through the stomata.