50 
Journal oj Agricultural Research 
Vol. XXX, No. 1 
Corresponding values of Q and r 
Q 
r 
Q 
r 
0.0 
0.000 
0.5 
0.409 j 
.1 
.079 
! - 6 
.500 
• 2 
. 158 
! .7 
.598 
.3 
.239 
1 -8 
.707 
• 4 
.322 
! .9 
.833 
j 1.0 
1 
1.000 
Yule states that for corresponding 
values of Q and r the probable error of 
Q is less, not greater, than that of r, 
that is, if we form Q and r for the same 
material the probable error of the for¬ 
mer constant is the smaller. The ratio 
of the standard error of Q to the standard 
error of r is very close, as shown in the 
following table taken from Yule (152 ): 
Ratio of the standard error of Q to the 
standard error of r for equal numerical 
values of Q and r 
Q 
Ratio 
Q 
Ratio 
0.1 
1.001 
0.6 
1.061 
.2 
1.005 
.7 
1.095 
.3 
1.012 
.8 
1.155 
.4 
1.023 
.9 
1.283 
.5 
1.038 
1.0 
1.000 
FLORET DISJUNCTION AND SPIKELET DISARTICU¬ 
LATION 
Table XI presents the summarized 
data obtained in the study of the 
relation between floret disjunction and 
spikelet disarticulation. These data 
show clearly that some relation exists 
between these characters, although it is 
less pronounced in some of the strains 
than in others. 
The basifracture type of floret dis¬ 
junction and the abscission type of 
spikelet disarticulation might naturally 
be expected to be correlated. Simi¬ 
larly floret disjunction by disarticula¬ 
tion and spikelet disarticulation by 
fracture might be expected to be closely 
associated because these combinations 
are typical of the two species. If. 
progenies of the heterofracture floret 
disjunction are not included, the results 
are as follows: 
Floret disjunction 
Spikelet disarticulation 
by— 
by— 
Abscis¬ 
sion 
Semiab¬ 
scission 
Fracture 
Basifracture.__ 
Per cent 
39.9 
12.4 
Per cent 
30.4 
18.5 
Per cent 
29.7 
69.1 
Disarticulation_ 
Apparently the correlation between 
floret disjunction by disarticulation and 
spikelet disarticulation by fracture as a 
rule is more pronounced than that be¬ 
tween floret disjunction by basifracture 
and spikelet disarticulation by abscis¬ 
sion. The coefficient of association (Q) 
in this case was determined by adding 
the number of kernels in which floret 
disjunction was by heterofracture to 
that by basifracture and by adding 
those in which spikelet disarticulation 
was from abscission and semiabscission 
respectively. Arranged in this way, 
the data are as follows: 
Spikelet disartic¬ 
Floret disjunction by— 
ulation by— 
Abscis¬ 
sion and 
semiab¬ 
scission 
Fracture 
Basifracture.-... 
Heterofracture.... - - 1 
} 2,179 
956 
Disarticulation__ 
2,764 
6,183 
Q=0.672±0.003 
These data indicate that a high degree 
of association exists (Q = 0.672 ±0.003) 
between certain phases of spikelet disar¬ 
ticulation and certain phases of floret dis¬ 
junction. Spikelet disarticulation re¬ 
sulting from abscission and semiabscis¬ 
sion apparently is closely associated 
with floret disjunction by basifracture 
and heterofracture, while spikelet disar¬ 
ticulation by fracture is associated with 
floret disjunction by disarticulation. In 
other words, the two byzantina charac¬ 
ters are associated as also are the two 
sativa characters. 
SPIKELET DISARTICULATION AND BASAL HAIRS 
The data on correlation between 
spikelet disarticulation and basal hairs 
are presnted in Table XII. It is evi¬ 
dent that correlation exists between 
spikelet disarticulation by fracture 
(without a basal cavity) and the ab¬ 
sence of basal hairs. Correlation exists 
between the basal cavity (resulting 
from abscission) and the presence of 
basal hairs, but this correlation does not 
seem to be as marked as the former one. 
In determining the value of Q for these 
characters, the kernels disarticulating 
by semiabscission were added to those 
disarticulating by abscission and the 
abundant long, abundant midlength, 
and few classes of basal hairs were all 
combined into one class and considered 
as basal hairs present, the data being 
arranged as follows: 
Spikelet disarticulation 
Basal hairs 
by— 
Present 
Absent 
Abscission_ _ . . . 
| 4,354 
589 
Semiabscission_ 
Fracture.... 
1, 855 
5,284 
Q=0.909±0.001 
