1916] Beeves: Inheriiance of Extra Bristles in Drosophila 509 



The results were so definite that it does not seem necessary to quote 

 at length. In every case when normals were mated with normals the 

 result in numbers hatched was larger than when extra was crossed 

 with extra. Often low numbers were obtained when extra was crossed 

 with normal. A large amount of sterility was found in extra crosses, 

 but in all matings of normal with normal there was no indication of 

 sterility. 



5. Absence of Sex Linkage. — The extra flies taken from the orig- 

 inal mass culture were five in number, three females and two males, 

 each crossed with normal. The families from the males were less 

 viable, a fact not especially significant as there were many conditions 

 that made death possible. 



In the families from the females the ratios between male and female 

 are shown in table XXI. 





TABLE XXI 









Showing Numbers 



OF Males 



AND Females 





Family 



Extras 



Extras 

 $ 



Normals 



Normals 

 ? 



Y Fi 



6 



3 



90 



68 





3 



4 



24 



24 





7 



6 



53 



48 



Y F„ 



2 



3 



49 



39 





4 



1 



35 



45 





4 • 







2 



9 



X 



1 



1 



78 



49 



- 



3 



12 



48 



52 





1 



2 



40 



42 













54 



44 



From table XXI it appears that extra bristles occur in males and 

 females in practically the same ratio. The males both in normal and 

 extra matings hatched first and this may explain the slightly larger 

 number of males. 



Family 

 J D 



y e 

 a t 





TABLE XXII 









Showing 



Absence 



OF 



Sex-linkage 







Number of 

 bristles 



<S 5 



Normals 





Norm: 

 ? 



als 



Extras 



Extras 



5 4 



59 





42 





1 



1 



4 5 



24 





24 





5 



4 



5 4 



28 





10 





3 



3 



4 6 



40 





50 





1 







