1 70 J. K. BREITEXBECHEP. 



Metz ('14) states that low viability of the apterous flies causes 

 more normals in the F 2 . This is also true in Bruchus since 

 there are more normals in the F 2 , which consists of a total of 65 

 winged females, 16 apterous females, and 76 winged males. 

 The ratio is approximately a 4 : I instead of a 3 : I ratio, because in 

 such matings there would naturally be more pure dominants 

 concerned. Aside from this the males do not show the trait 

 which would also tend to make the ratios less normal. 



Metz ('14) again, with reference to apterous flies being sex 

 linked, states that the absence of apterous flies in the FI indicates 

 that the character is not sex linked. It is true in Bruchus that 

 the FI produces no apterous beetles, but this is not a safe criterion 

 in Bruchus, because all males are always winged, regardless of 

 their transmitting the apterous trait, that they may carry. The 

 F 2 is the ideal place to determine it. All of the PI matings were 

 apterous females with winged males. The F 2 if sex linked should 

 give half females apterous and half winged or the reciprocal cross 

 would give all females winged. This is not true for apterous in 

 Brnchus, because the ratio approximates a 3: I ratio in the F 2 . 

 The character is therefore not sex linked. 



In conclusion, apterous is a recessive trait seen only in the 

 females. It has a high degree of sterility possibly from the 

 North Carolina stock in which it originated. Lastly, it has a 

 lower viability than the normal. 



BIBLIOGRAPHY. 

 Lancefield, D. E. 



'18 Three Mutations in Previously Known Loci. Amer. Nat., Vol. LII., p. 

 264-269. 



Metz, Charles W. 



'14 An Apterous Drosophila and its Genetic Behavior. Amer. Nat., Vol. 

 XLVIII., p. 675-692. 



