68 



SEX-LINKED INHERITANCE IN DROSOPHILA. 



LINKAGE OF CHERRY, DEPRESSED, AND VERMILION. 



The linkage value 38 (see table 49) indicates that depressed is some- 

 where near the opposite end of the series of sex-linked factors from bar. 

 The locus could be more accurately determined by finding the link- 

 age relations of depressed with gens at its end of the chromosome. 

 Accordingly, depressed females were crossed to cherry vermilion males. 

 Fi gave wild-type females and depressed males. The daughters bred 

 again to cherry vermilion males gave the results shown in table 50. 



mC 



Fig. G. — Depressed wing. 



The data only suffice to show that the locus of depressed is about 

 midway between cherry and vermilion, or at about 15 units from yellow. 



The Fi males in the last experiment did not have their wings as much 

 depressed as is the condition in stock males, and in F2 most of the 

 depressed winged males were of the Fi type, although a few were like 

 those of stock. This result suggests that the stock is a double recessive, 

 /. e., one that contains, in addition to the sex-linked depressed, an 

 autosomal factor that intensifies the effect of the primary sex-linked 

 factor. 



Table 50. — Pi depressed 9 X cherry vermilion cf cT . 



First 

 generation. 



Wild- 

 type 

 9 9. 



21 



De- 

 pressed 



31 



Second generation. 



Refer- 

 ence. 



19 I 



W^' 



Wjdp 



9 91 Cherry -^ Cherry j ,, 



^ De- J ^ Ver- 



59 



ver- 

 milion 



23 



pressed 



24 



pressed 



I miiion 



d^. 



w<= 



dp V 



De- 

 Cherry P''^"'^^'^ 



mihon 

 c?. 



w^dp^ 



Cherry 



de- 

 pressed 



ver- 

 milion 



Wild- 

 type 



