The Endosperm in Inheritance 151 



fundamental situation as described should enable us 

 to analyze such cases and reach a conclusion as to the 

 expected results. 



A law which EAST (i) has formulated in reference to 

 xenia is pertinent: "When two races differ in a single 

 visible endosperm character, in which dominance is 

 complete, xenia occurs only when the dominant parent 

 is male (pollen parent). When the two races differ in 

 a single endosperm character, in which dominance is 

 incomplete, or when they differ in two characters, both 

 of which are necessary for the development of the visible 

 differences, in both of these cases xenia occurs when 

 either parent is male." This may be called " normal" 

 xenia. What may be called " abnormal" xenia must 

 now be considered. 



WEBBER (3) in 1900, in experimenting upon xenia in 

 corn, uncovered some interesting abnormalities. Pollen 

 from a red-grained race, applied to silks of a white- 

 grained race, should result in solid red grains if xenia is 

 normal. In most cases WEBBER obtained this result; 

 but sometimes there appeared grains which showed 

 blotches of red and white in a kind of irregular mosaic. 

 For these cases he constructed an ingenious and reason- 

 able explanation. 



Normally the second male nucleus fuses with the 

 fusion nucleus, and the result is a solid red grain. In 

 some cases, however, the second male nucleus does not 

 join with the two other nuclei, but all three divide 

 separately without having fused, and in such a case the 

 mature grain is white with red streaks. In still other 

 cases the two polar nuclei fuse, but the second male 

 nucleus does not enter into the complex, and in this case 



