HERITABLE CHARACTERS OF MAIZE 
IV. A LETHAL FACTOR—DEFECTIVE SEEDS 
D. F. JoNEs 
Connecticut-A gricultural Experiment Station, New Haven. 
ETHAL factors are familiar in 
corn in the form of several dif- 
ferent kinds of chlorophyll defi- 
ciencies. White and virescent 
seedlings represent heritable characters 
which stop growth as soon as the food 
stored in the seed is exhausted. Golden 
plant color and many forms of striping 
permit growth and reproduction, but at 
a reduced rate. 
A new factor, which shows itself in 
the form of aborted seeds with either 
entirely empty pericarps or badly shriv- 
eled seeds, has been found, being com- 
pletely lethal in its action in some cases 
and partially so in others. Develop- 
ment of both the embryo and endo- 
sperm is stopped completely or greatly 
reduced shortly after fertilization. How- 
ever, the fertilization process is sufficient 
to start the pericarp, and this developes 
unchecked to very nearly as full an 
extent as if the contents were present, 
although the empty hulls are greatly 
compressed by the crowding of the nor- 
mal seeds adjacent. Fortunately the 
growth of the pericarps makes the dis- 
tribution of the abnormal seeds easily 
apparent. The behavior of this char- 
acter indicates that it is recessive and 
due to a single factor difference. This 
gene is called defective seed and is desig- 
nated de. 
OCCURRENCE OF DEFECTIVE SEEDS 
Attention was first called to this 
condition by some ears of corn grown 
on plants of ordinary field varieties 
which had been self-fertilized for the 
first time. A considerable number of 
plants of four varieties chosen as among 
the highest yielding sorts in this locality 
were raised. Two of these were dent 
and two flint varieties of rather distinct 
type and have been widely grown in the 
state. 
Altogether about 75 selfed ears were 
obtained from the four varieties, and in 
three of these 8 ears were found which 
were definitely segregating into normal 
and defective seeds. After such a factor 
was once recognized it was noted in 
many other kinds of material from 
widely different sources. It has also 
been noted by others working with corn. 
It has been detected in several different 
types of popcorn, in sweet corn, and in 
locally grown varieties as well as in trop- 
ical sorts, so that unquestionably it is 
widely distributed and may occur in 
practically all kinds of corn. In field- 
pollinated plants cross-fertilization tends 
to keep the character hidden from sight. 
Chance recombination allows a few seeds 
to appear on plants heterozygous for the 
abnormality, but since a few abortive 
seeds are common on nearly every ear 
of corn, due to various causes, such 
seeds pass without particular notice. 
When the plants are self-fertilized, 
then if the genetically defective seeds 
are present at all they appear in ap- 
proximately 25 per cent of the seeds and. 
because of their greater numbers and 
distribution over the entire ear, they 
show up plainly. The character is 
manifested in several different degrees 
and it is not yet certain that they are all 
due to the same factor. This remains 
to be seen, but that there is a definitely 
inherited factor there can be no doubt. 
The difference between the recessive 
seeds and the normal seeds on the same 
ears is usually pronounced, and classifi- 
cation can be easily made. 
DESCRIPTION OF THE CHARACTER 
In its extreme manifestation the peri- 
carps develop but are completely 
empty. Such unfilled capsules are dis- 
tinct from partially developed ovules 
due to incompleted growth or ineffective 
161 
