GENE FOR FOURTH CHROMOSOME OF DROSOPHILA 331 



mated together, to show the distribution of bent with respect to all 

 three previously known chromosomes. The pinks were also mated 

 together. The latter cross should show the distribution of bent 

 with respect to Chromosomes I and II only, as all the flies were 

 homozygous for pink, the mutant gene in Chromosome III. 



The composition of the pink flies used as parents, with the 

 paternal and maternal genes which they contained, was as follows: 



Fi male Paternal genes — Gray Fink Bent 



Maternal genes sex Black Pink Straight 



Fi female Paternal genes sex Gray Pink Bent 



Maternal genes sex Black Pink Straight 



The count of offspring of this cross of pink flies resulted as 

 shown in table 2. 



TABLE 2 

 All i itdividuith pink 



Numbers of females expected = numbers of males expected. 



The results conform with the theoretical expectation on the 

 assumption of independent segregation between black, sex and 

 bent. 



The composition of the parents in the cross of red flies was as 

 follows : 



Fi male* Gray Red Bent 



sex Black Pink Straight 

 Fi female sex Gray Red JBent 



sex Black Pink Straight 



* The paternally derived allelomorphs are on the upper line, the maternal on the 

 lower. 



THE JOURMAL OF EXPERIMENTAL ZOOLOGY, VOL. 17, NO. .3 



