Table 1.

Heterochromatic lethals of chromosome 2 induced by I-R dysgenesis

Cross	Het.	Chr.	Lethals	Frequency
1a	2R	1,564	11	7 × 10−3
1b	2R	1,003	0	0
2a	2L	1,102	8	7.2 × 10−3
2b	2L	1,131	0	0
3a	2R	1,204	5	4.1 × 10−3
3b	2R	896	0	0
4a	2R	919	2	2.2 × 10−3
4b	2R	381	0	0
5a	2R	1,024	2	1.9 × 10−3
5b	2R	967	1	1 × 10−3
6a	2L	909	2	2.2 × 10−3
6b	2L	712	0	0
7a	2R	1,142	6	5.2 × 10−3
7b	2R	993	0	0
8a	2L	746	1	1.3 × 10−3
8b	2L	520	0	0
Exp.	2R	5,853	26	4.4 × 10−3	χ2 = 16.24
C.	2R	4,240	1	2.3 × 10−4	P ≤ 0.001
Exp.	2L	2,757	11	4 × 10−3	χ2 = 11.17
C.	2L	2,363	0	0	P ≤ 0.001

Crosses 1a and 2a = Ch (R) × C-S (I); 3a = Ch (R) × M-5 (I); 4a = cn (R) × Cy/Pm (I); 5a and 6a = cn (R) × C-S (I); 7a and 8a = Ch (R) × b lt rl cn (I), in which Ch = Charolles; C-S = Canton-S. The reciprocal control crosses are indicated with b. Het., the heterochromatic location of lethal mutations as judged by complementation with 2Lh or 2Rh deletions; Chr., number of chromosomes scored; Lethals, number of lethal chromosomes; Frequency, frequency of lethal chromosomes; Exp., total dysgenic crosses; C., total nondysgenic controls.