number of rows of grain is a multiple of four are more 
numerous than ears in which the row number is not a 
multiple of four. Even before the suggestion was made, 
East (7) had shown that such is, indeed, the case. East 
offered no morphological explanation for the multimodal 
distribution and it still remains to be satisfactorily ex- 
plained. Reeves (unpublished) has suggested that the 
peculiar distribution reported by East may be the result 
of past selection for straight-rowed ears, a suggestion 
based on the fact that there is a tendency, discovered by 
Fujita (8), for ears with an odd number of ranks of paired 
spikelets to be twisted. 
But whatever the explanation of the low frequency of 
ears with ranks of paired spikelets in odd numbers, the 
fact that any ears of this kind occur has generally been 
regarded as evidence against the fusion theory. Perhaps 
more weight has been assigned to this evidence than is 
deserved. There are undoubtedly ways (one will be men- 
tioned later) in which rows of spikelets might be lost 
without leaving readily discoverable vestiges. Further- 
more if fusion is thought of in a phylogenetic rather than 
in an ontogenetic sense, it 1s scarcely necessary to assume 
that the compound structure resulting from fusion must 
still exhibit all of the features of its original component 
parts. Finally the absence of anatomical evidence of fu- 
sion is by no means final proof that it has not occurred. 
There are numerous structures in plants in which ana- 
tomical evidence for fusion is lacking or at least not read- 
ily discernible, but which are nevertheless regarded as 
compound structures. In these instances, however, some 
other kind of evidence for fusion is usually at hand; for 
example, a series of forms involving different species 
which illustrates a transition from the condition in which 
the components are entirely separated to that in which 
they are completely joined. In the case of maize there 
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