GENE MUTATIONS 



in the active condition, which makes counting 

 tedious. The secondaries are extended lateral- 

 ly at an angle of 45 to 60 degrees from the 

 midline, and they also droop somewhat. Both 

 deviations from the normal are apparently the 

 result of deformation at the axilla. The pri- 

 maries may be held almost normally, or they may 

 be extended laterally at an angle approaching 

 or equal to that of the secondaries. The pri- 

 maries are not held downward like the seconda- 

 ries, but in the normal plane as though the ax- 

 illa of the primary is normal, and their posi- 

 tion is simply the result of a defect in the 

 secondaries. The abdomen is slightly elevated 

 as if for balance, especially in cases v/here 

 both pairs of wings are widely spread. The fe- 

 males are sterile but the males seem to be of 

 normal viability. (Discarded) 



BROKEN, bk (wings). In 1934 a male with mutant 

 wings appeared in the progeny of an X-rayed 

 wild-type female (dosage about 4500 R units). 

 In this mutation the outer margin of the pri- 

 mary wings is broken and the v;ings are very 

 fragile. The veins in the primary wings often 

 resemble those of shot-veins. Broken and shot- 

 veins have been tested together and found to 

 segregate independently (Fig. 7). Both sexes 

 are fertile and of normal viability. 



AEROPLANE, ae (wings and tarsi). This mutation 

 appeared in the progeny of an X-rayed female 

 (dosage about 3500 R units) in 1934. The wings 

 are stiffly outstretched, and the tarsi are 

 black and brittle. The males are unable to 



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