IOWA ACADEMY OF SCIENCES. 



20 L 



The wall joining the testa is greatly thickened and in some 

 cases provided with minute canals, which ( onnect adjoining cells. 

 ==p-^^ The walls of the endosperm 

 consists of pure cellulose. 

 The cells are densely filled 

 with protein grains, but no 

 starch. The so-called gluten 

 meal of commerce consists of 

 the wall of the ovary, the 

 testa, the aleurone layer and 

 some starch cells. The layer 

 following the aleurone con- 

 sist of thinner- walled, some- 

 what irregular, but usually 

 elongated cells filled with 

 starch, at least in our dent 

 and flint corns. The starch 

 grains appear regularly striated and with a "nucleus. " 



The embryo is surrounded by a small and regular row of 

 cells where_it joins the endosperm. These are followed by the 



Fig. 7. 

 Popcorn, a, epidermis; c, capsule; and tesU 

 , aleurone layer; s, starch. 



Pop;orn. a, epidermis; c, capsule; and testa; d, aleurone layer; g, starch cells. 



