IOWA ACADEMY OF SCIENCES. 



203 



"We may now discuss some varietal differences. Harz has 

 indicated some differences but the varieties studied by him were 



j^not named. In yellow dent and pop- 

 corn the starch grains are solidly 

 packed. The starch grains of the 



' popcorn are much larger. The outer 

 cells of the wall of the ovary are 

 larger and more elongated. The cell- 

 walls of the aleurone layer are pro- 

 vided with pore canals. In the Mex- 

 can corn of the popcorn type the wall 

 ^.of the ovary has large cells and those 

 of the testa are also large. These 

 cells as well as the aleurone cells are 

 colored brown. In the Mexican sweet 

 corn the blue pigment is carried in the 

 aleurone layer as well as in the testa. 



Fig. 10. 

 Sweet corn, Early Minnesota, a, 

 epidermis; c, capsule and testa; 

 d, aleurone layer; s, starch cells. 



