all (seven) pairs. In the fourth row the pediceled spike- 
let is at the right in all (eight) pairs. A systematic ar- 
rangement is also closely approached in the first and fifth 
rows, the former having the pediceled spikelet at the 
right in six of the seven pairs, the latter having the ped- 
iceled spikelet at the left in eight of the ten pairs. 
It is to be noted further that the second and fifth rows 
in this diagram are mirror images of the first and fourth 
with respect to the position of the pediceled and sessile 
spikelets. 
How does the arrangement in Fig. EK compare with 
the arrangement theoretically expected if the ear of maize 
had originated from the spike of teosinte by yoking and 
twisting? Plate XII, fig. A shows the arrangement in 
teosinte when the abortive spikelet becomes functional, 
as it does in some cases, especially when the tunicate gene 
is superimposed upon teosinte by crossing and backcross- 
ing. Here the arrangement is completely systematic and 
the two ranks are mirror images of each other with re- 
spect to the position of pediceled and sessile spikelets. 
Plate XII, fig. B shows the theoretical arrangement 
after yoking has occurred. This arrangement has actually 
been seen in a segregate from a maize-teosinte hybrid in 
which the spikelets were yoked, both spikelets of each 
pair were functional and the pediceled spikelets were 
distinguishable from the sessile ones. 
Plate XII, fig. C shows the theoretical arrangement 
resulting from yoking combined with twisting of the 
axis. Here rows one and three and rows two and four 
(rows diametrically opposed to each other on a cylindri- 
cal rachis) are mirror images of each other with respect 
to arrangement as well as position of the spikelets. 
In two important characteristics, systematic arrange- 
ment of the spikelet and mirror imagery, K155 is like 
the ear theoretically developed from the spike of teosinte 
[ 62 ] 
