No. 639] SHORTER ARTICLES AND DISCUSSION 381 



reduced, salmon, untl saliiioii iiKidili. !-. Sufficient crosses have 

 been made, however, to iippi'oxiiiuitr tlicii- positions, which are as 

 follows: reduced, 5.24; salinuii inndilirr, 5.94; salmon. 41.;J3. 



Description of Tables 

 Tabic I gives the results of mating the F, flies produced by 

 crossing an orange reduced male to a wild type female. All tlie 

 females are wild type. Of the F, males 850 are wild type. 

 585 reduced, 785 orange reduced, 586 salmon, 15 orange, and 6 

 salmon reduced. 



Tal)le II gives the F, r.^sults of matin- a salmon male to a 



Table IIT (<n and U". fi'ivt'^ U') the results of crossing an F, 

 reduced male (from an orange reduced male X a wild femalel 

 to a salmon female. The females are wild type and the males 

 salmon. In (&) the F^ wild type females were mated to orange 

 males. The orange males were used instead of the salmon to 

 bring out orange in the females. Orange males and females 

 appear. Hence the Fj reduced males must have carried the gene 

 for salmon modifier. 



Table IV gives the F, results of crossin- a salmon male to a 

 reduced female. Orannv males appear. Wruro tht^ reduci^d line 

 must be homozygous for salmoii iiKulili. i-. 



Zoological Laboratory, 



AX APPARATl'S FOK M HM^ODISSECTIOX 



