STORAGE OF FOOD IN THE SEED 



17 



the same relation to the plant of which it is a part that 

 one cell of a honeycomb does to the whole comb. Cells 

 are of all shapes and sizes, from little spheres a ten-thou- 

 sandth of an inch or less in diameter to slender tubes, 

 such as fibers of cotton, several inches long. To get an 

 idea of the appearance of some rather large cells, scrape a 

 little pulp from a ripe, mealy apple, and examine it first 



ep ■ 

 m . 



■g.oooQOpooooo 



'J 





Fig. 8. Section through Exterior Part of a Grain of Wheat. 



0, cuticle or outer layer of bran ; ep, epidermis ; m, layer beneath epider- 

 mis; 171/, sc7i, layers of hull next to seed-coats; 6r, », seed-coats; Kl, 

 layer containing proteid grains; st, cells of the endosperm filled with 

 starch. (Greatly magnified.) 



with a strong magnifying glass, then with a moderate 

 power of the compound microscope. To see how dead, 

 dry cell-walls with nothing inside them look, examine (as 

 before) a very thin slice of elder pith, sunflower pith, or 

 pith from a dead cornstalk. Look also at the figures in 

 Chapter Vll of this book. Notice that the simplest plants 

 (Chapter XXIII) consist of a single cell each. The study 



