14 
BULLETIN 1468, U. S. DEPARTMENT OF AGRICULTURE 
standard deviations of the percentage of crossing over in the two 
sexes may be examined. These have been assembled in Table 7 for 
13 progenies where reciprocal crosses between identical plants were 
available. Since the rate of crossing over is not alike for the two 
sexes, and to avoid a spurious difference due to the error inherent in 
the calculation of standard deviations of percentages centered at 
other than 50 per cent, the observed standard deviations have been 
corrected to a basis of 50 per cent. 
Table 7 shows that there is on the average a slightly greater vari- 
ability in the female than in the male gametes, but the difference is 
not statistically significant. None of the individual progenies 
showed a significant difference, and it seems safe to conclude that 
the variability of crossing over is no greater in one sex than in the 
other. 
Table 7. — Standard deviations of the percentage of crossing over in male and 
female gametes 
([Comparison restricted to reciprocal crosses] 
Female gametes 
Progeny 
Num- 
ber of 
ears 
Number 
of seeds 
Percent- 
age of 
crossovers 
a 
o-jo 
Dh 416L3L1C1L1L22 
4 
7 
8 
7 
5 
5 
5 
7 
17 
49 
11 
13 
13 
1,919 
3,400 
3,064 
2,933 
2,331 
3,296 
4,068 
3,523 
7,336 
24,627 
5,284 
4,995 
4,122 
24.75 
25.80 
31. 41 
31.00 
27.16 
28.25 
32.57 
39.40 
35.50 
20.47 
22.16 
20.62 
25.10 
2. 96=1=0. 71 
4. 65± . 84 
6. 78±1. 14 
4. 50± . 81 
5. 70=1=1. 21 
3. 87± . 83 
7. 39±1. 58 
3. 21=fc . 58 
2. 9lrfc . 34 
5. 24d= . 36 
5. 68=fc . 82 
4. 83=fc . 64 
4. 18=b . 55 
3. 43±0. 82 
Dh 416L3L1C1L1L1L23 
5. 31 =b .96 
Dh 416L3L1C1L1L2L23 
7. 32=1=1. 23 
Dh416L3LlClLlL3L23 
4.86=1= .88 
Dh 416L3L1C3L21 
6. 41=bl. 37 
Dh 416L3L1C3L1L22 . 
4. 30± .92 
Dh 416L3L1C5L21 
7. 88-4-1. 68 
Dh416L3LlC5L4L23 
3. 29± . 59 
Dh 416L3L1C5L4L1L24 . . . 
3. 04± .35 
Dh 416L3L1C5L3L1R23 
6.49=1= .44 
Dh 416L3L1C5L3L2R23 
6. 82=b . 98 
Dh 417L1L2L1L21 
5. 95=fc .79 
Dh 417L1L2L1L2L23 
4.81± .64 
Male gametes 
Difference 
(0-«>9 
Progeny 
Number 
of seeds 
Percent- 
age of 
crossovers 
a 
O"60 
Dh 416L3L1C1L1L22 
1,885 
2,104 
2,722 
1,387 
4,100 
2,266 
7,352 
3,661 
6,300 
27, 517 
'3,683 
4,693 
3,757 
20.53 
24.50 
32.36 
30.50 
23.20 
22.11 
29.65 
35.80 
37.60 
18.07 
27.42 
16.71 
29.30 
2.04±0.49 
6. 51=1=1. 17 
6. 10±1. 03 
5. 87=1=1. 06 
4.33=fc .92 
4.46=1= .95 
8. 97=fcl. 91 
2. 22±1. 07 
2. 93± . 34 
4. 02=fc . 28 
3. 98± . 57 
2. 71± . 36 
4. 64== . 61 
2. 53±0. 60 
7. 57=1=1. 36 
6. 52±1. 03 
6. 37±1. 15 
5. 13=1=1. 09 
5. 38±1. 14 
9. 81±2. 10 
2. 32=1= . 42 
3. 02=b . 35 
5. 22± . 36 
4. 46± . 64 
3. 63± . 48 
5. 10=fc . 95 
0. 90±0. 99 
Dh 416L3L1C1L1L1L23 
-2. 26=bl. 67 
Dh 416L3L1C1L1L2L23-. 
. 80=hl. 61 
Dh 416L3L1C1L1L3L23 
— 1. 51=1=1. 45 
Dh 416L3L1C3L21 .-_ 
1. 28=hl. 75 
Dh 416L3L1C3L1L22. - 
-1.08=bl. 47 
Dh 416L3L1C5L21.-- 
-1.93=1=2.62 
Dh 416L3L1C5L4L23 
. 97=fc . 72 
Dh 416L3L1C5L4L1L24 
. 02± . 49 
Dh 416L3L1C5L3L1R23 
1. 27=b . 57 
Dh 416L3L1C5L3L2R23... 
2. 36=1=1. 17 
Dh 417L1L2L1L21 
2. 32=b . 92 
Dh 417L1L2L1L2L23 _ .-. 
- .29=1=1. 15 
Mean ._ . 
. 628±. 212 

In 4 of the 13 progenies the rate of crossing over is higher in 
the male than in the female gametes. If the difference between 
the crossover rates is assumed to be due to a differential viability 
of the gametes, the variability of crossing over would be expected 
