plants deficient for the factor expressing the cultivated- 
type grain characters. Sometimes the fatuoids lack the 
entire chromosome which carries this factor. It is evi- 
dent that A. sativa has all the genetic factors necessary 
to produce the A. fatua grain characters, but in addition 
it has a partially dominant inhibitor which suppresses the 
development of the fatwa grain characters and produces 
the cultivated-type grain. This inhibitor is designated 
the C-factor and the chromosome on which it is located 
is called the C-chromosome. 
The C-factor of A. sativa has been found to be par- 
tially dominant in crosses with wild species other than 
A. fatua. Florell (1981) reported that in crosses of A. 
sativa X A.sterilis the sativa-ty pe attachment of the lower 
floret (spikelet) was almost completely dominant over the 
wild type and due to a single factor. Jones (1940) found 
the F; of the crosses A. longiglumis XA. sativa and A. 
sativa XA. barbata to have non-articulate florets. 
Theories accounting for the origin of A. sattva must 
agree with the genetic facts. Since the sativa grain type 
is due to a single factor pair, only one intermediate form 
is possible between the wild and cultivated grain types. 
This would be due to the heterozygous condition. An 
extensive series of intermediate forms from the wild spe- 
cies to A. sativa showing gradual reduction of the articu- 
lation-surface of the florets, reduction in pubescence, or 
reduction of awns has nothing to do with the origin of 
A. sativa. Far from solving the problem, such interme- 
diate forms raise the additional question of their own 
origin. Similarly the facts of genetics are at variance 
with the opinion of Coffman (1946) that an origin of 4. 
sativa from A. sterilis requires only loss mutations, while 
an A. fatua derivation requires additive mutations which 
are believed to be more difficult to obtain. The evidence 
indicates that both A. sterils and A. fatua lack the C- 
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