False-colour scanning electron micrograph of a fractured leaf of the turnip, Brassica rapa. The horizontal lines of cells near top & bottom form the epidermis of the leaf. The epidermis, partic- ularly the underside, is dotted with stomata: pores that regulate the leaf's exchange of gases with the outside. The leaf interior contains mesophyll cells, some seen broken open. They consist of palisade mesophyll (top) & spongy mesophyll (bottom). The tightly packed palisade cells contain chloroplasts, sites of photosynthes- is. The spongy mesophyll cells are loosely packed, with few chloroplasts; they are more involved with gas exchange. Magnification: x55 at 35mm size. Green tint (leech"). BW original is B745/074. Ref: MICROCOSMOS, fig. 4.9, page 72"