ZEA 173 



the grain that is formed by this double fertilization will have 

 a yellow endosperm. Thus double fertilization explains 

 the phenomena of xenia. It is of course true that, if in the 

 above, pollen from the white endosperm-bearing plant were 

 used, xenia would not be shown. Xenia, the visible effects 

 of double fertilization, has been found in the following con- 

 spicuous cases in corn— in each case below, the plant men- 

 tioned first is the female : 



Non-starchy-seeded plants crossed with starchy-seeded 

 plants always give starchiness. 



Non-yellow endosperm crossed with yellow shows yellow. 



Non-colored aleurone layer crossed with purple gives 

 purple. 



Non-colored aleurone layer crossed with red gives red. 

 /variation in the Corn Plant. — There are marked individual 

 differences in the plants of an ordinary field of corn. The 

 plants may vary in height, vigor, leaf production, height of 

 ears on the stalk, shape of ears, composition of kernel, 

 etc. Moreover, there is scarcely any other crop plant in 

 which we find more abnormalities or monstrosities than we 

 do in corn. We have mentioned hermaphroditic flowers, 

 both in the tassel and ear as one abnormality; to these we 

 may add branched ears, tassels with a few or many kernels, 

 variegated leaves, and variegated ears. In corn it is possible 

 for the different kernels of an ear to receive pollen from many 

 different plants, and from its own tassel. Hence, it usually 

 happens that the grains on the same ear have different 

 hereditary characters as shown by their varied progeny. 

 This is well shown in variegated ears. If xenia occurs, the 

 effects of this crossing may be evident the same season. For 

 example, if pollen from dent corn fertilizes some of the ovules 

 on an ear of sweet corn, those ovules appear starchy, while 

 the other grains of the ear of corn, fertihzed with sweet corn 



