of grain were interrupted. He stated that among many 
ears examined, in which rows were dropped between 
the base and the tip of the ear, in no instance were the 
dropped rows either adjacent or separated by two rows, 
but always (when the dropped rows could be determined 
with reasonable certainty) on opposite sides of the ear. 
Weatherwax (17) showed, however, that when rows 
are dropped between the base and tip of the ear, it is 
always a pair of adjoining rows which is eliminated and 
not rows on opposite sides of the rachis. It is difficult to 
see how Collins, usually a keen observer, could have been 
so completely in error in this instance. Actually his state- 
ment, though highly inaccurate, has some basis in fact; 
for in segregates of maize-teosinte hybrids there is in 
some four-ranked ears a definite tendency for the spike- 
lets in one plane to be predominantly paired while those 
in the plane at right angles are predominantly single. In 
other words in ears in which yoking is obvious, there is 
a definite tendency for the spikelets diametrically op- 
posed to each other on the axis to be alike with respect 
to the abortion and development of spikelets. 
In considering the yoking hypothesis there is some 
danger, as has already been apparent in the case of the 
fusion hypothesis, of thinking only in rigid terms. Is it 
not possible that as the axis becomes thickened, the yok- 
ing, if it occurs at all, would become less obvious and the 
tendency for spikelets on opposite sides of the rachis to 
exhibit identical behavior would become less pronounced 
and would, indeed, disappear completely / Is it necessary, 
in other words, to conclude that yoking has not occurred 
in the development of the maize ear because the spike- 
lets on opposite sides of the axis, in ordinary ears of 
maize, are not alike in their behvaior? These questions 
will be discussed further when new evidence from maize- 
teosinte hybrids is considered. 
[ 45 ] 
