36 
BULLETIN 1164, U. S. DEPARTMENT OF AGRICULTURE. 
the 17 characters determined in F 3 which did not show definite seg- 
regation ratios in F 2 , the extremeness of the individual or individuals 
among the 22 F 2 parents which had, respectively, the highest and 
the lowest value for the character in question, the coefficients of 
variation or standard deviations of the F 3 progenies of these extreme 
individuals, and the average of the coefficients of variation or standard 
deviations of the F 3 progenies whose parents had given values nearest 
the mean of the F 2 population. Extremeness is expressed by taking 
the difference between the value of the high or low parent individual 
and the opposite extreme of the whole F 2 population as a percentage 
of the difference between both extremes of the whole F 2 population. 
An extremeness of 100 per cent indicates that the parent individual 
was at one or the other end of the F 2 frequency distribution, while 
an extremeness of 50 per cent would indicate that the parent individual 
was close to the mid-point of the F 2 distribution. 
Table 10. — Coefficients of variation or standard deviations of the most variable and 
least variable F 3 progenies and of the F 2 and parental populations of Holden-Pima cot- 
ton hybrids. 
Coefficient of variation or standard deviation. 1 
Significance of differ- 
ence in variability 
F 3 progeny giving— 
F 2 (entire 
popula- 
tion.) 
Holdon. 
Pima. 
(D-r-E) between 2— 
Most 
and 
least 
vari- 
able 
F 3 . 
Most 
vari- 
able F 3 
and 
F 2 . 
Character. 
Highest 
C or a. 
Lowest 
C or <r. 
Least 
vari- 
able F 3 
and 
less 
vari- 
able 
paren- 
tal. 
Axis: 
Length 
31.7 ±4.98 6.9 41.26 
22.740.85 
12.84 .46 
14.94: .54 
29.641-14 
33. 6± 1.32 
16. 2± .58 
21.1± .78 
12. 8± .46 
21. 7± .80 
12. 7± .46 
1.8± .064 
1.3± .046 
.9± .032 
11. 6± .41 
9.2± .33 
12. 1± .44 
8.6± .30 
13.2±1.65 
14.9±1.S7 
13.2±1.65 
27. 2±3. 57 
33.3±4.53 
7.3± .89 
15.9±1.99 
13.9±1.73 
9. ldzl-11 
6.4± .78 
.34- .037 
.4± .019 

5. 1± .62 
3.4± .42 
4.5± .55 
1.8± .22 
11. 14:1-55 
8.5±1.17 
7.2± .99 
12.4±1.67 
16.3±2.20 
5.2± .72 
10.2±1.41 
8.8±1.2l 
8.4±1.16 
10.2±1.41 
.1± .013 


4.2± .55 
2.5± .33 
4.3± .57 
1.3± .17 
4.8 
5.5 
3.8 
3.4 
6.6 
4.9 
3.7 
5.5 
5.1 
4.3 
5.7 
7.7 
8.5 
4.1 
4.6 
4.2 
41.8 
42.1 
+ 1.7 
42.1 
43.3 
+ .8 
4 .7 
41.1 
+2.2 
41.9 
41.4 
+3.9 
41-5 
42.4 
+3.3 
42.0 
-?^ 
Internode num- 
ber. 
Internode length. 
Fruiting branch: 
Length 
First internode.. 
Leaf: 
Length 
17.7 ±2.29 
20.1 ±2.99 
45.9 ±7.85 
62.5 ±8.67 
18.1 ±2.23 
4.6 ± .69 
8.0 ±1.02 
16.9 ±3.13 
4.8 ± .81 
6.1 ±1.03 
-2.9 
+ .6 
41.3 
-4.9 
+ .7 
Width 
23.6 ±3.42 
9.5 +1.60 
- .3 
14.3 ±1.25 5.9 ± .89 
32.6 ±4.93 6.8 ±1.15 
16.7 ±2.04 6.6 ±1.11 
2.28± .33 1 .38± .06 
2.514: .31 ! .12± .02 
1.104 .13 
19.9 43.48 I 5.2 ± .69 
22.1 ±3.90 ! 3.9 ± .66 
16.4 ±2.08 6.7 + .96 
-1.9 
Lobe index 
Vein angle 
Callus color 
Petiole hairiness 
Petal color 
-1.0 
+ .1 
+4.6 
+6.0 

Boll: 
Length 
Diameter 
+ 1.1 
+ 1.9 
+2.2 
Lock number ... 
10.3 ± .76 
2.3 ± .33 
9.6 
+2.1 
+2.7 
1 For the three graded characters, leaf callus color, petiole hairiness, and petal color, the standard devi- 
ations are compared. For all other characters the comparison is of coefficients of variation. 
2 A plus sign ( + ) indicates that the first and a minus sign (— ) that the second of the populations com- 
pared is the more variable. 
In many of the characters the most extreme of the 22 parent in- 
dividuals were comparatively remote from the corresponding extreme 
of the entire F 2 population. With an extremeness of less than 80 per 
cent, indicating that the location of the parent individual on the F 2 
distribution was more than one-fifth of the distance from the extreme 
in question, we should not expect to find a marked approach to ho- 
