80 Nebraska Agricultural Exp. Station , Research But. 20 
Chart 2. — Comparative effects of the crossing of pure lines (inbred) 
versus the crossing of commercial varieties. Average yields of 
grain per acre for seven pure line hybrids at left and thirteen 
variety hybrids at right. Data taken from Tables 14, 18, 25, 28, and 
30 averaged for two years, 1916 and 1917. The 1917 yields for in- 
bred parents are for composite planting and are taken from Table 
25. 
IMMEDIATE EFFECT OF FOREIGN POLLEN ON KERNEL WEIGHT 
The study of the immediate effect of foreign pollen upon 
the weight of the corn kernel has aroused much interest. It is 
well known that the embryo of a kernel of corn is the direct 
product of the union of the male and female gametes. The 
embryo is a rudimentary corn plant and is just as homozygous 
or heterozygous as is the plant which it produces when planted. 
As the result of double fecundation in corn, its endosperm de- 
velopment is also subject to the influence of both gametes. The 
color and type of endosperm are very readily influenced bv the 
immediate effect of foreign pollen, which gives rise to the well- 
known phenomenon of xenia. 
