Extranuclear Genes 



371 



figure 29-1. Marcus M. Rhoades (in J 959) examines striped corn plants in 

 the foreground. Unstriped corn plants are in the background. 



cause it originated partly from green and 

 partly from white tissue. When the kernels 

 in such an ear are planted in rows corre- 

 sponding to their positions in the cob, the 

 result is not all green, all white, all striped, 

 nor a random mixture of these types, but 

 groups of green and albino seedlings (Fig- 

 ure 29-2). This outcome suggests that 



striping actually occurs in the ovary and per- 

 sists in the cob. Other tests of this strain 

 show that the greenness or whiteness of a 

 seedling is independent of the color of the 

 parental part forming the pollen used to 

 produce the seed. Moreover, appropriate 

 crosses show that none of the genes in the 

 paternal or maternal chromosomes is in- 



