EFFECT OF SELECTION ON CROSSOVER VALUES 
347 
which was without doubt due to high temperature, as our records 
indicate. The fertihty was low and we obtained with much 
effort from en-masse matings in the F32 and F33 only forty-eight 
and eighty individuals, respectively, while under ordinary con- 
ditions several thousand would have been possible. As soon as 
normal conditions were restored, the usual low crossover values 
were again found. The F41 showed a rather unexpected rise 
TABLE 4 
Series B — Continued 
GENERATION 
CROSSOVERS 
TOTALS 
CROSSOVER VALUES 
Fjo » 
6 
144 
4.17 
F31 
7 
171 
4.09 
F32 
4 
48 
8 33 
Fss 
10 
80 
12.50 
F34 
52 
643 
8.09 
F35 
48 
1,147 
4.18 
F36 
55 
1,032 
5 33 
F37 
46 
814 
5 65 
F38 
39 
697 
5 60 
F39 
55 
954 
5 77 
F40 
72 
1,074 
6 70 
F41 
94 
1,015 
9 26 
F42 
463 
8,564 
5 41 
F4, 
47 
901 
5 22 
F44 
103 
1,312 
7 85 
F45 
43 
661 
6 51 
F46 
59 
992 
5 95 ■ 
F47 
69 
1,021 
6 76 
F48 
45 
734 
6 13 
F49 
81 
1,081 
7 49 
Fso 
96 
1,375 
6.98 
(9.26 per cent), but since there were no unusual temperature 
conditions, we must regard this somewhat higher value as with- 
out peculiar significance. The subsequent generations dropped 
to about 6 per cent again. 
