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THE AMERICAN NATURALIST [Yol.XLIX 



alter, the abnormal males first change to normal, then the 

 heterozygous females, and lastly the homozygous females. 



Several attempts were made to find out if, when the 

 female, heterozygous for abnormal abdomen, is her- 

 self abnormal, her offspring are more likely to be abnor- 

 mal than when she is normal. There is evidence every- 

 where throughout the tables to show that the condition 

 of the mother has absolutely no effect on her offspring. 



In December .January. 1!»14. the following experiments 

 were made which are the converse, in one respect, of 

 some of the preceding experiments since black abnormal 

 females were used. The crosses are indicated below. 



(1) Black, white, abnormal $ by gray, white, normal 



(2) (iray, red, abnormal $ by gray, white, normal c?. 



(3) Black, white, abnormal $ by black, white, normal <$. 



(4) Gray, white, abnormal ? by black, white, normal £ 

 The F, females from (1) compared with (2) should 



show whether females heterozygous for black (and ab- 

 normal) are less abnormal than those pure for gray; 

 provided, white and red eye make no difference in the 

 development of abnormality. The F, female from (3) 

 compared with (4) should reveal whether pure black 

 heterozygous for abnormal are less abnormal than flies 

 heterozygous for gray as well as abnormal. 



The results need not be given in detail. It was found 

 that the (F, ) daughters from (1) show the same degree 

 of abnormality as those in (2)- Hence heterozygosis in 

 black need not have any influence on the realization of ab- 

 normality. The mother- were not, however, in the same 

 bottles, but in different cultures kept as much alike as 

 possible. To this extent the experiments are unsatisfac- 

 tory. It was found that F, females from (3) were like 

 those from (4), hence no evidence was found that the 

 heterozygous type is more affected than the homozygous 

 black. But here also the flies were reared in different 

 bottles. In order to overcome this difference, some ab- 

 normal females that were heterozygous for black were 

 bred to black normal males (both having white eyes). 



