was 28.6, although each plant was pollinated several 
times with corn pollen. 
Data taken on phenotypic characters of these BCs 
plants revealed several significant differences between 
this population and Inbred 208, the only corn line which 
had entered the ancestry of the hybrids, but we shall dis- 
cuss only one of these—number of rows of alicoles. This 
character is not only one by which the parents of this 
cross differ, but it is also one of the generic characters 
distinguishing corn and Tripsacum. With all the plants 
growing in the same relatively uniform nursery, planted 
the same day and given the same treatment, Inbred 203 
had a mean of 6.48 rows of alicoles and the BCs hybrids 
a mean of 4.38. This difference was highly significant 
statistically, and the deviation of the hybrids from their 
corn parent was in the direction of Tripsacum. 
During the 1956 season, 290 offspring resulting from 
the fourth backcross to Inbred 203 were grown, and, 
except for a few differences which will be pointed out, 
the results were essentially a repetiton of those obtained 
in 1955. The mean number of alicole rows for Inbred 
203 in 1956 was 6.36 and that for the hybrids 4.15, and 
again the difference between the means was highly sig- 
nificant. Although 288 plants of this population of 290 
were completely pollen sterile and showed no greater 
ovule fertility than did the third backcross generation, 
two plants dehisced an abundance of pollen and produced 
approximately full ears of grains when selfed. The ear 
of one of these fertile plants had six rows of alicoles and 
that of the other seven rows, both numbers near the 
average of Inbred 203. It might be of incidental interest, 
however, to note that in certain other characters, such as 
number of tassel branches and height of upper ear node, 
one plant or the other was not within the observed range 
of variation of Inbred 203; and the deviation here again 
[ 368 J 
