Plant Genetics 



of EAST'S red and purple corn, the colors being located 

 in the aleurone. 



There is another phase of this situation to which 

 attention should be called. By pollinating the silks 

 of a white-grained individual with pollen from a red- 

 grained individual xenia is secured, the resulting grains 

 being red like those of the pollen parent. In the recip- 

 rocal cross, however, that is, pollinating silks on a red- 

 grained individual with 

 pollen from a white- 

 grained individual, a differ- 

 ent result is obtained. 

 The resulting grains are 

 not white like those of the 

 pollen parent, but red like 



Pericarp 



Endosperm 



Embryo 



Cross-Section of 

 Corn-Seed 



FIG. 35. Diagram of corn seed 



those of the ovule parent. 

 There is no xenia, there- 

 fore, for the pollen has no 

 immediate effect upon the 

 developing endosperm. 

 This seeming difficulty, 

 however, is easily explained. When the pollen parent 

 is white and the ovule parent is red, the endosperm gets 

 its characters from both parents, and since red is domi- 

 nant over white the resulting endosperm will be red 

 because the female nuclei that entered into the triple 

 fusion carried the factor for red endosperm; and there- 

 fore the pollen from the white parent seemed to have 

 no effect. The mechanism works in all cases, but owing 

 to dominance, xenia appears only in certain cases. 

 There is no need to discuss all of the Mendelian situations 

 in which xenia may occur. An understanding of the 



