50 



SEX-LINKED INHERITANCE IN DROSOPHILA. 



eosin miniature males. The daughters that result from such a cross 

 give only the amount of crossing-over between eosin and miniature 

 (as 29.7), but the males give the cross-over values for eosin lethal (9.9), 

 lethal miniature (15.4), and eosin miniature (25.1). The data for this 

 cross are given in table 25. 



Table 25. — Total data upon linkage of eosin, lethal 2, and miniature, from 



Morgan, iQi4b. 



Females. 



Total. 



Cross- 

 overs. 



Cross- 

 over 

 value. 



M 



ales. 



w^ m!wM2 w« 



1, 



w. 1.2. m 



m 



lo m 



-A- 



Cross-over values. 



Eosin 

 lethal 2. 



Lethal 2 Eosin 

 miniature, miniature. 



15,904 



4.736 



29.7 



5,04s 



653 



1,040 



14 



9-9 



iS-4 1 25.1 



A similar experiment, in which eosin and vermilion were used instead 

 of eosin and miniature, is summarized in table 26. 



Table 26. — Total data upon the linkage of eosin, lethal 2, and vermilion, from 



Morgaii, igi4b. 



Considerable data in which lethal was not involved were also obtained 

 in the course of these experiments and are included in the summary of 

 the total data given in table 27. 



Table 27. — Summary of all data upon lethal 2, from Morgan, iQi4h. 



The amount of crossing-over between eosin and lethal is about lo per 

 cent and the amount of crossing-over between lethal and miniature is 

 about 18 per cent. Since the amount of crossing-over between eosin 



