AN APTEROUS DROSOPHILA AND ITS 

 GENETIC BEHAVIOR 



CHARLES W. METZ 

 Department of Zoology, Columbia University 



Among the various mutants of the fruit-fly, Drosophila 

 ampclophila, which have arisen from cultures in this 

 laboratory, is one entirely destitute of wings, and hence 

 called apterous. 1 The study of the heredity of this form 

 has been difficult because of its almost complete (appar- 

 ent) sterility. In order, therefore, to determine to which 

 of the three groups of linked characters of Drosophila it 

 belonged I was obliged, in most crosses, to make use of 

 heterozygous flies that carried the factor for apterous. 

 As this process is unique in certain regards, it will be 

 described in some detail. 



Methods of Study 

 At first it was thought that the apterous mutant was 

 completely sterile, since none of the first flies, as they 

 appeared occasionally in certain cultures, could be crossed 

 even with normal individuals. At last, however, offspring 

 were obtained from an apterous female by a wild male, 

 and a permanent line started. But this line could not be 

 perpetuated by means of apterous individuals, for these 

 were unable to breed. 2 It had, therefore, to be kept up 

 by means of heterozygous, winged flies. The method was 

 as follows : The original cross of winged by apterous gave 

 in F 2 approximately 3 winged to 1 apterous. Of the 

 winged class approximately two thirds were heterozygous 

 for apterous, and when mated together gave the same 



1 This apterous fly is quite distinct from that called wingless in earlier 

 papers by Morgan, and now known as vestigial. 



2 Only twice, aside from the original mating, wore apterous individuals 



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