186 



BREEDING CROP PLANTS 



what similar manner as in the flint-flour cross, the difficulty of 

 a correct classification by inspection is apparent. 



The endosperm of corn may be either yellow, pale yellow, 

 or white. In some crosses there is almost complete dominance of 

 the yellow color, while in other crosses the F\ is intermediate or 

 pale yellow. The results of most yellow-white crosses may be 

 explained by one factor or by two multiple factors. It is impos- 

 sible to tell by inspection whether a particular yellow variety con- 

 tains one or two factors for yellow. The only sure method is 



FIG. 43. Two first year self-fertilized ears of Minn. No. 23 showing the lethal 

 endosperm character. 



to note whether the segregation approaches 3:1 or 15:1. White 

 (1917) has recorded a cross in pop corns between yellow and 

 white endosperm varieties in which white is the dominant char- 

 acter. The results were explained by supposing that the white 

 variety carried an inhibitory factor, A, and also a factor for 

 yellow or F, while the zygotic condition of the yellow variety 

 was YY. 



The inheritance of aleurone color is even more complex than 

 the inheritance of yellow endosperm color. The aleurone may 

 be either colorless, mottled, red, or purple. Three factors are 



