sessile and pediceled spikelets are often readily distin- 
guished, it should be possible to draw some inferences 
about spikelet arrangements in the ear by studying them 
on the central spike. 
The spikelets on the central spike of the tassel are 
borne in more or less distinct rows. These are less clear 
cut, to be sure, than those on the ear, but can neverthe- 
less be traced with a fair degree of accuracy. The posi- 
tion and arrangement of the spikelets on a central spike 
can be charted by tracing a vertical rank of spikelets from 
its base, determining the position of each pair by actual 
measurement and noting whether the pediceled spikelet 
is at the right or left of the sessile one. This is repeated 
with each vertical rank until the entire circumference of 
the spike has been charted. 
A chart of the spikelets of the central spike, prepared 
in this way, is almost the equivalent of peeling the sur- 
face of the rachis, unrolling it and spreading it flat. 
Plate XII, figs. D and E, shows in diagrammatic form 
the relative position and the arrangement of sessile and 
pediceled spikelets on portions of central spikes of two 
inbred strains of maize; the first a strain of the Guarany 
variety ; the second a North American strain well known 
to agronomists, K155. 
It is to be noted that in the Guarany maize the ar- 
rangement of the spikelets with respect to the position 
of the sessile and pediceled is a random one, or at least the 
deviation from randomness on any single row is clearly 
not significant. 
The central spike of K155 presents quite a different 
aspect. In one row (the center row in the diagram) the 
spikelets are arranged at random, but in the remaining 
rows the arrangement is either clearly systematic or it 
approaches this condition. In the second row from the 
left, for example, the pediceled spikelet is at the left in 
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