random. In ears derived from maize-teosinte crosses 
which have been repeatedly backcrossed to maize, the 
arrangement is definitely systematic. 
The entire subject of spikelet arrangement deserves 
more study. In the meantime it is already reasonably 
clear that on the central spike of the tassel, at least, the 
arrangement approaches a random condition in some va- 
rieties and is systematic in others. There is reason to sus- 
pect that these differences occur also on the ears. It is 
supposed that the random arrangement is characteristic 
of ‘‘pure’’ maize; the systematic of Tripsacum-contam- 
inated maize. Varieties which are completely random or 
completely systematic in the arrangement of their spike- 
lets are perhaps not common, the majority of varieties 
probably exhibiting some degree of intermediacy be- 
tween the two extremes. 
Twisted Ears and Odd Numbers of Paired 
Rows. Attention has been called to Fujita’s observa- 
tion that ears in which the number of rows of paired 
spikelets is odd are often slightly twisted with the rows 
of grain exhibiting a tendency to form weak spirals. And 
mention has also been made of the fact that there is, in 
North American maize at least, a preponderance of ears 
with rows of paired spikelets in even numbers as opposed 
to those with rows in odd numbers. The two phenomena 
are probably related and both may well be the result of 
Tripsacum influence. At any rate they are most strik- 
ingly displayed in segregates of maize-teosinte hybrids. 
The predominance of ears with rows of spikelets (in this 
case single as well as paired spikelets) in even numbers is 
well illustrated by the following frequency distribution. 
Population Number of Rows of Spikelets _ Total 
2 3 4: 5 
(Durango Teosinte < Maize) F2 65 45 58 9 177 
(Nobogame Teosinte X Maize) F2 86 71 115 27 299 
[ 64 | 
