tend to make the cob stiffer and more indurated, and to 
give the rows of grain a rigid vertical alignment some- 
times accompanied by spaces between pairs of rows. The 
end product of these various tendencies is most com- 
monly an eight-rowed ear in which spikelets in one plane 
are diametrically opposed to each other, while those in 
the plane at right angles to the first are also opposed to 
each other but in positions alternating exactly with those 
in the first plane. 
Here, then, is precisely the kind of ear which would 
have developed according to Collins’ yoking and twist- 
ing hypothesis. The only difference is that the rachis 
having become large, and sometimes pithy, the yoking 
is no longer actually apparent. But these ears also con- 
form completely to Weatherwax’s conception of the ear 
as an example of spiral phyllotaxy. Indeed the spiral 
phyllotaxy is so rigid that the addition of another pair 
of rows of grain, the equivalent of a half-spiral, results 
in an unbalanced phyllotaxy usually accompanied by a 
twisting of the cob. This type of ear is obviously quite 
different from that illustrated by the Guarany pod corn; 
and yet the one is nothing more than a modified form 
of the other. 
That there are differences in maize varieties with re- 
spect to phyllotaxy in the branches of the tassel has al- 
ready been noted by Anderson (1) who finds a spiral 
phyllotaxy predominating in some varieties, a whorled 
phyllotaxy apparently characteristic of others. 
Other Differences in Maize Types 
If there are in nature two types of ears, one with a 
whorled phyllotaxy another with a spiral phyllotaxy, it 
is reasonable to suspect that other differences between 
the two types also exist. 
[ 59 | 
