GRASSES OP IOWA. 



63 



on the kernels. The literature is given quite fully by Keller- 

 man and Swingle.* 



Webberf says: "In the writer's experiments it was found 

 that the plumbeous or blueish-black color of the aleurone 

 layer of the endosperm in the cuzco and Black Mexican races 

 was apparently shown in almost all cases as xenia when these 

 races were used as the pollen parents in crossing with white 

 or yellow races of Dent, Flint or sweet corn. In all of the 

 cases observed by the writer no exception has been found to 

 the rule first asserted by Koernicke, that xenia is shown only 

 in the endosperm, the portions of the kernel outside of the 

 endosperm remaining unaffected. " 



Fig. 46. Maize caryopsls; a, epi- 

 dermal cell of caryopsis; c, cary- 

 opsis below testa; a, aleurone layer; 

 s, starch layer. (Pammel and 

 King.) 



Fig. 47. Caryopsis of Mexican corn, 

 popcorn type; a, epidermal cells of cap- 

 sule; c, capsule; t, testa; d, aleurone 

 cells; s, starch layer. (Pammel and 

 King.) 



•Experiments in Grossing Varieties of Corn. IBull. Kan. State Coll. Agr. Exp. Sta., 

 17: 151-174. pi. 3, and Ann. Rep. Kan. Agrl. Coll. Exp. Sta. 2: 



+ For literature, see valuable paper by Webber. Bull. U. S. Dept. Agrl. Div. Veg 

 Path, and Phys. 22: 1900. 



