through yoking and twisting. But in a third important 
feature, the sequence of pediceled and sessile spikelets, 
there is a distinct difference. In the ear developed from 
teosinte by yoking and twisting (Fig. C) the sequence is 
PSPSSPSP. No matter at what point this sequence 
begins it always involves at some point on the circum- 
ference two rows of sessile spikelets adjacent to each 
other and diametrically opposed on the rachis to two 
rows of pediceled spikelets adjacent to each other. In 
K155 (fig. FE) on the other hand (omitting the single row 
with random arrangement and letting the letters S and 
P respectively, represent the predominating condition in 
each row of spikelets) the sequence is SPPSSPPS. Here 
no matter on which row the sequence begins, the pat- 
tern is one of two rows of sessile spikelets alternating 
with two rows of pediceled spikelets. 
This sequence is not unique to K155. It has been ob- 
served in other strains where the arrangement of spikelets 
approaches the systematic. 
The sequence illustrated in Fig. C has also been ob- 
served in several varieties. his means, if it means any- 
thing at all, that the ear of maize sometimes behaves as 
though it had been derived from the spike of teosinte by 
twisting of the axis in the sense in which Collins used 
the term. Whether this sequence is as common as the 
other remains to be determined. 
Other evidence that both random and systematic ar- 
rangement of spikelets occur is found in ears which are 
partly or wholly staminate at the apex. When wholly 
staminate both spikelets are usually, though not always, 
sessile as they are when wholly pistillate. When the 
spikelets are mixed, however, the pistillate one is usually 
sessile, the staminate one pediceled. In the Guarany va- 
riety the arrangement of staminate and pistillate spike- 
lets, when the two are mixed, seems to be essentially 
[ 63 ] 
