20 A STUDY OF WHEAT. 



bright yellow. Nitrogen is found only in cell-contents, and is 

 never found in cell-walls. 



8. Inside of the layer of albumen is found only one struc- 

 ture until we reach the embryo, at the base of the grain. It 

 is composed of large, thin-walled hexagonal cells, loaded with 

 starch, see Fig. 2. To see these cells plainly under the mi- 

 croscope a very thin section must be cut from the central part 

 of the grain with a razor, or a sharp knife, and then washed 

 off carefully with a camels-hair brush, so as to remove the 



Fig. i. Outer Layer of Albumen. X 200. 



grains of starch, when we find a delicate white structure re- 

 sembling a honey-comb in all except color. At the center of 

 the grain the cells are the largest, and are quite uniform in 

 shape and size, measuring nearly i-io of a millimeter (1-250 

 of an inch) in diameter. At the surface of the albumen the 

 cells are quite long and narrow, and lying in such a way that 

 they appear to radiate from the center toward the surface. 

 The walls are delicate and nearly transparent, showing under 

 a high magnifying power the different structures or layers of 

 cellulose. The cells are loaded with starch grains, as seen at 

 a, Fig. 2. 



9. Just inside the hexagonal cells, which fill the inside of 

 the grain, and at the same time surrounding the embryo, is 

 found a single row of empty compressed cells, quite difficult 

 to demonstrate. 



10. The embryo occupies the lower end of the grain, and 

 is a small oval body about one millimeter in width and two 

 in length. The main object in life for the wheat is the pro- 

 duction of this embryo. The development of the stem, the 

 branching and expanding of the leaves, the whole life and his- 



