‘‘resembling a string of triangular beads”’ (Plate XI, fig. 
A). As the axis shortens or the rachis segments increase 
in size, the segments tend to lose their linear orientation 
and to assume a zigzag arrangement (Plate XI, fig. B). 
Finally adjacent segments, whose spikelets arise on op- 
posite sides of the axis, become diametrically opposed to 
each other and yoked to each other (Plate XI, fig. C). 
The other steps which Collins described also occur 
regularly and here, too, my material is better for pur- 
poses of illustration than was his. The change from soli- 
tary to paired spikelets is shown in Plate XI, figs. A and 
D. This may occur either before or after the rachis seg- 
ments have become yoked. The change from distichy 
to polystichy to produce an eight-rowed ear is shown in 
Plate XI, figs. E and F. Collins attributed this change 
to a twisting of the axis and the term is satisfactory if it 
is not used too literally. What actually occurs is that the 
yoked segments become arrayed in two planes instead 
of one, an arrangement which makes much more efficient 
use of the circumference of the rachis as a spikelet-bearing 
surface. Collins showed diagrammatically how ears with 
additional row numbers would be produced by additional 
‘“‘twisting’’ of the axis. These were not encountered in 
my material. A number of ten-rowed ears occurred, but 
they were, for the most part, ‘‘disharmonious’’ ears with 
twisted cobs. Apparently the only ‘‘normal’’ ears in 
which the yoking is readily discernible are four-rowed 
and eight-rowed ears. 
An important change which Collins did not note, or 
at any rate did not describe, is the compaction of the in- 
florescence. A spike which has passed through the three 
stages which he described is still far removed from an 
ear of maize. It must pass through still another stage, a 
change from a lax spike to acompacted spike. Plate XI, 
fig. G illustrates an eight-rowed spike which has become 
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