VARIABILITY IN LINKAGE OF CHARACTERS OF MAIZE 
Table 2. — Formula for deriving p from Q for a number of gametic 
combinations 1 
Gametic combination 
Zygotic 
ratio 
Formula 
A B 
a b 
a W 
-4 & v a 6\ 
a B x ab) 
a b ) 
a b 
A~b 
ab 
a B ~ aB. 
AB B' a b B' \ 
abb' X abb'r 
A b B' a b B 
a Bb' X 
b B' \ 
b Vr 
A B b'a b B'\ 
ab B' 
ab * 
A~l % 
-x 
abV /" 
Ab\ 
abi 
A_b\ 
a B* abi 
A B B' a b V 
abb' X abb' 
A b B' a b b' \ 
a Bb' X abb'i-- 
AB B',A~BB'\ 
abb' abb' 
A b B' Ab B'\ 
a Bb' X i 
1 B'\ 
BVY- 
B' Abb'\ 
Y *abb' f" 
A B B '„Abb'\ 
abb' 
Ab B'Abb- 
a Bb' 
r*- 
bb'. 
A B V a B V \ 
abb' X abb'} 
A b B \, a B b' \ 
aBV X abb'} 
1:1 
1:1 
3:1 
3:1 
3:5 
3:5 
1:1 3:5 
3:1 1:1 
1:1 
1:1 
3:1 
3:1 
1:1 
1:1 
1:1 
1:1 
3:1 
3:1 
3:1 
3:1 
1:1 
1:1 
1:3 
1:3 
9:7 
1:3 
3:5 
3:5 
2Q 
p»= 
V4-2Q(Q-l)-2 
2Q 
3Q-4+Vl6-15Q» 
6Q 
P= 
Q-2+V4-3Q* 
2Q 
Q-8+V&4+8Q-47Q? 
6Q 
Q-2+V4-2Q-2Q» 
Q-4+Vl6-15Q» 
2Q 
» A and B are the dominant allelomorphs of the factor pairs, A a, B b. A' and B' are the dominant 
allelomorphs of the pairs, A' a', B' b' . The primed letters represent complementary genes. The curved 
line connecting the factor symbols indicates a linkage of those factors. p=the percentage of crossing over. 
Since the fluctuations in ratios due to errors of sampling become 
smaller as the ratio departs from 0.5, and the change is measured by 
the change in Vpg, it is possible to correct for these changes by multi- 
plying the observed standard deviation by Q.5/\/pq. This changes the 
standard deviation to that expected had the mean ratio been 0.5, or 50 
per cent. Standard deviations corrected by the factor 0.5 /Vpq are 
designated o- 50 . This correction neglects the fact that for small 
ratios plus variations will be more frequent than minus variations, 
