SENSITlXn^ ()!• DKOSOPHILA (iHRM CKl.L STAGES TO X IRRADIATIOX 



stocks previously described ^^ was synthesized and used. The treated 

 chromosomes are represented by asterisks: 



Po y w In49 



(yellow, white) 



y sC* r InS w^ 



. ? ? (virgins) x _^ ^ 



y \v In49 X sc^Y(y+) 



(non-yellow, apricot, forked) 



P, y SO* f InS w^ 



************** 



V 



1 $ (virgin) x 



************** 



y w In49 



(yellow, whitish-apricot) 



-c2 



^^ 



sc8.Y(y+) 

 (non-yellow, forked) 



Fj y so* f InS \v« 



************** 



1 



X 



c2 



y 



which had been y sc'* f InS w'' 

 f fertilized by their ************** ^^ 

 $ brothers of either 



the composition: .^- 



sc" 



,Y(y+) 



' (yellow, forked) 



(non -yellow, apricot, forked) 



Fj y w In49 



**************** 



or: 



y w In49 



1 



C^C? 



sc° 



■Y(y^) 



(yellow) (non-yellow, white) 



F2 absence of non-yellow, apricot-eyed, forked or non-yellow white-eyed, 

 males = sex-linked recessive lethal mutation of maternal origin. 



Here again, our scheme relies on easily discernible markers, yellow-body 

 colour (y), white eyes (w), apricot eyes (w*), and forked bristles (f). The 

 yellow whitish-apricot treated Pj females should be collected as virgins. 

 To detect scx-linkcd Icthals, F^ females and males can be shaken over into 

 fresh vials at the end of their hatching period and left in this way for 2 to 3 

 days in order to ensure that they mate w ith their brothers. After this period 

 the flies can be counted from each vial separately. The females should be 

 separated from the males (which can then be discarded after they have been 

 counted and it has been noted that both classes of males are present; the 



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