40 



SEX-LINKED INHERITANCE IN DROSOPHILA. 



LINKAGE OF MINIATURE AND SABLE. 



The miniature wing has been described (Morgan, Science, 1911) 

 and the wing figured (Morgan, Jour. Exp. Zool., 1911). The gen for 

 miniature Hes about 3 units to the right of vermiHon, so that it is still 

 closer to sable than is vermilion. The double recessive, miniature 

 sable, was made up, and males of this stock were bred to wild females 

 (long gray). The wild-type daughters were back-crossed to double 

 recessive males and gave the results (mass cultures) shown in table 13. 



Table 13. — Pizvild 9 9 X miniature s able d^c/', 



miniature sable cf cf- 



B. C. Fi wild-type 9 9 X 



Since the results for the male and the female classes are expected to 

 be the same, the sexes were not separated. The combined data give 

 7 per cent of crossing-over between miniature and sable. 



LINKAGE OF VERMILION, SABLE, AND BAR. 



Bar eye has been described by Mrs. S. C. Tice (1914). It is a domi- 

 nant sex-linked character, whose locus, lying beyond vermilion and 

 sable, is near the right end of the chromosome series, that is, at the 

 end opposite yellow. 



In the first cross of a balanced series of experiments for the gens 

 vermilion, sable, and bar, vermilion (gray not-bar) entered from one 

 side ( 9 ) and (red) sable bar from the other ( cf ). The daughters were 

 bar and the sons vermilion. The daughters were back-crossed singly 

 to the triple recessive males vermilion sable (not-bar), and gave the 

 data included in table 14. 



In the second cross, vermiHon sable (not-bar) went in from one side 

 ( 9 ) and (red, gray) bar from the other. The daughters were bar and 

 the sons were vermilion sable. Since these sons have the three reces- 

 sive factors, inbreeding of Fi is equivalent to a triple back-cross. The 

 results are given by pairs in table 15. 



