STRUCTURE OF THE PLANT-CELL 5 



known as chloroplasts . On examining a leaf of the Canadian 

 Pondweed (Elodea canadensis) under the high power, each of 

 the more or less rectangular cells will be found to contain a 

 number of chloroplasts, which will be seen from one of two 

 aspects (Fig. 3). Some, situated along the sides of the cell, 

 are viewed in profile and appear as flattened ellipses (O.S.), 



FIG. 2. Staminal hairs of the Spiderwort (Tradescantia) . A, a single 

 hair ; B, a single cell showing the nucleus and strands of cytoplasm 

 passing across the vacuole ; C, a hair plasmolysed with sea-water. 



whilst others lying against the upper or lower walls, and conse- 

 quently seen from the surface, present a round or oval form (Su.). 

 Each chloroplast is thus a solid body which has more or less 

 the shape of a biconvex lens. 



If attention be centred on a single cell, the chloroplasts lying 

 against the upper face can be brought clearly into view by 

 turning^the fine adjustment ; on focussing to a lower level, 



