1916] Reeves: Inheritance of Extra Bristles in Drosophila 503 



TABLE XI 



Normal X Normal Matings in Pairs 



Actual 

 ratios 



95:2 



Ratios 

 to 1 



47.5:1 



Expectation 

 95.5:1.5 



Agreement 

 63:1 



Conclusion 

 63:1 



98:5 



19.6:1 



96.6:6.4 



15:1 



15:1 



75:1 



75:1 



74.8:1.2 



63:1 



63:1 



67:0 



67:0 





63:1 



63:1? 



either 15 :1 or 3 :1 or intermediate, but never 63 :1. On a Mendelian 

 interpretation it would therefore appear that in matings between 

 normals and extras two or three equivalent factors were always pres- 

 ent, while in matings between extras there were one or two factors, but 

 never three. 



In table XI are shown the results of crossing together normal sibs 

 in four families of the F^ generation. The ratio of normals to extras 

 is high, approximating 63 :1 in three families and 15 :1 in the fourth. 



In tables XII, XIII and XIV the ratios of the three preceding 

 tables are arranged serially in order to determine whether they are 

 uniformly distributed or fall into groups corresponding to the presence 

 of one, two or three factors. In table XII the results are indecisive, 

 although there is a considerable gap between 10.4:1 and 14.5:1. In 

 table XIII the results are clearer, three families falling close to 3 :1, 

 five families near 5 :1 and four families near 15 :1. The families of 

 table XIV evidently group themselves similarly into two series. 









TABLE XII 











Normal X Extra Matings, Serially Arranged 





Actual 



ratios 



to 1 



Actual 

 numbers 



Actual 

 ratios 

 to 1 



Actual 

 numbers 



Actual 

 ratios 

 to 1 



Actual 

 numbers 



Actual 

 ratios 

 to 1 



Actual 

 ratios 



5.3:1 



48:9 



14.5:1 



29:2 



20:1 



60:3 



40:1 



80:2 



7.6:1 



38:5 



16.6:1 



100:6 



21.2:1 



83:4 



42:1 



42:1 



7.7:1 



101:13 











50:1 



50:1 



8:1 



40:5 



17.5:1 



158:9 



23.3:1 



70:3 



50:1 



50:1 











25.5:1 



51:2 



51:1 



102:2 



0.4:1 



73:7 



18:1 



36:2 



26.5:1 



98:4 



90:1 



90:1 











33.3:1 



100:3 



90:1 

 95:1 



90:1 

 95:1 



5:1 





15:1 





25:1 





63:1 





