78 



SEX-LINKED INHERITANCE IN DROSOPHILA. 



entirely absent. This result is due to a lethal factor, lethal 5, which 

 appeared in this culture for the first time. 



The males of the two cultures 149 and 151 give the order of gens 

 as facet, vermilion, sable; that is, facet lies to the left of vermiUon and 

 toward yellow. The cross-over values are: facet vermilion 40; vermil- 

 ion sable 12; facet sable 42. Since yellow and vermilion usually give 

 but 34 per cent of crossing-over, this large value of 40 for facet ver- 

 milion shows that facet must lie verv near to yellow. 



T.\BLE 59. — Pi facet & X verviilion sable 9 9 



X vermilion sable cf d^. 



B. C. Fi wild-type 9 



LINKAGE OF EOSIN, FACET, AND VERMILION. 



In order to obtain more accurate information on the location of facet, 

 a facet male was mated to an eosin vermilion female. The Fi females 

 were mated singly to wild males and they gave the results shown in 

 table 60. The F2 females were not counted, since they do not furnish 

 any information. The evidence of table 60 places facet at i.i units to 

 the right of eosin, or at 2.2. 



Table 60. — Pi eosin vermilion 9 X facet c^. fi tcild-type 9 X "wild cf- 



