IOWA ACADEMY OF SCIENCES. 



201 



-c 



The wall joining the testa is greatly thickened and in some 

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



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- 



3 sist of thinner- walled, some- 

 what irregular, but usually 

 Fig. 7. elongated cells filled with 



Popcorn, a, epidermis; c, capsule; and testa; starch, at least in OUr dent 

 «', aleurone layer; s, starch. 



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. 8. 

 Popcorn, o, epidermis; c, capsule; and testa; a, aleurone layer; 8, starch cells. 



