Heritable Characters of Maize 165 
where they should occur in the ratio of 
two segregating plants to one normal. 
together with the fact that the parent 
ears were normal, indicates that a more 
complex situation may exist in this par- 
ticular material. 
The numbers obtained from all the 
ears together show the recessive seeds 
to be fewer than the expected numbers 
based on a single factor difference. A 
number of non-segregating ears in the 
same lots as the ears showing the de- 
fective seeds, as well as normal ears 
from unrelated sources, were examined, 
and from 1 to 5 per cent of partially 
developed seeds were found on many 
ears which might easily be included in’ 
the defective class. Therefore if the 
recessive seeds were in excess aS much 
as 30 per cent instead of the expected 
25, this would not be thought unusual. 
But the deficiency in numbers is clearly 
due to some influence. It may be that a 
certain proportion of recessives do not 
stimulate the pericarp to develop suffi- 
ciently, or the active competition on 
a crowded ear may prevent develop- 
ment enough so that all the defective 
seeds are included in the count. 
In the original lots of self-fertilized 
ears the segregating individuals are gen- 
erally smaller and more poorly devel- 
oped than the normal ears. This may 
be evidence that the same factor which 
prevents normal growth in the seeds in 
the homozygous recessive condition also 
reduces the vigor of the plants when in 
the hybrid condition. Further investi- 
gation is necessary to establish this, 
but the material all together indicates 
that this is the case. The defective 
seeds which will germinate have not 
been tested long enough to determine 
whether or not they are capable of 
completing their growth and reproducing 
themselves. 
In Fig. 15, which represents the 
original lot of selfed ears of one variety, 
specimen No. 12 shows partially de- 
fective seeds, while in the one num- 
bered 17 the recessive seeds are com- 
pletely aborted. The empty shells of the 
pericarps only remain. In Fig. 9 some 
of the progeny ears of these two plants 
PARTIALLY DEFECTIVE SEEDS 
Showing a few seeds completely aborted. 
The ‘partially developed seeds are small 
and usually very much shriveled.”” Pho- 
tograph by R. A. Emerson. (Fig. 13.) 
