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THE AMEBIC AN NATURALIST [Vol. XLVIII 



Beaded-winged flies of the F 1 generation are used as par- 

 ents, more Beaded-winged young are produced than when 

 normal-winged Fj flies are used. This holds true for each 



TABLE IV 



Matings Between F t Flies op the Cross Beaded by Wild, Showing 

 Percentages of Beaded Offspring in Individual Broods 



TABLE V 



Jack-crosses to Wild of F % Flies of the Cross Beaded X Wild, Show- 

 ing Percentages of Beaded Offspring in Individual Broods 



I S i i i i i 



Normal X Wild 9 



Beaded X Wild 3756312102 



of the five crosses shown in the two tables. Normal- 

 winged F x flies do, however, have some Beaded-winged off- 

 spring, both when mated among themselves, and also, 

 though more rarely, when back crossed to Wild. 



These F 2 and back-cross results give little satisfaction 

 at first sight to the student of Mendelism. If we suppose 

 that there is one gene on which the Beaded condition 

 depends, and that it is partially dominant, then Beaded 



TABLE VI 



Father Beaded.. 1,246 4.488 948 4,481 21.7 ' 17.5 



Mother Beaded . 894 2,959 1,139 2,684 23.2 



