176 



MAIZE 



CHAP, 

 V. 



which behaves as xenia ; the reciprocal cross, in which the 

 recessive allelomorph is brought in by the other parent, whether 

 male or female, does not materially alter the endosperm. 

 Xenia is therefore not due to the influence of sex, but is the 

 immediate manifestation of the dominant character, in the 

 Fj seed. 



Correns (1), Webber (2), and P2ast and Hayes (1) observed 

 several cases in which xenia occurred in only one half of the 

 endosperm. The last two authors suggest that these rare 

 phenomena are probably similar in nature to the gynandro- 

 morphs occurring in insects. They report having grown a 

 number of them to see if the tendency was inherited, but with- 

 out positive results. The present writer has met with a few 



Fig. 77. — Grain showing part starchy and part wrinkled characters. 



cases in which both the starchy and the wrinkled characters 

 appeared side by side in the same grain (Fig. JJ). These 

 occurred on heterozygous F., ears, and it was therefore not 

 possible to say definitely that they were due to xenia, but 

 this seems to be the most probable explanation of the 

 phenomenon. 



Experiments by East and Hayes confirm the observation 

 of Correns that in every case where xenia may be expected to 

 occur, the seeds showing xenia were always hybrids. This 

 fact was assumed to prove that the second male nucleus (IT 78) 

 always bears the same characters as the one that fuses with the 

 egg-cell to form the embryo, and that for this reason Mendelian 

 segregation of the gametes must have occurred previous to the 

 division of the pollen nucleus. 



