IN THE SECOND CHROMOSOME. 



321 



Comparison of table 18 with table 14 will show that the results 

 given by ^ - and by Cm are almost if not quite the same. 



'II r 



That is, homozygous C n r gives the same result as no C// r . 



HOMOZYGOUS C n WITHOUT Cm. 

 p r Crir . . C ni C II 



A , . 

 A female 



b p r c m r 

 was mated to a male 



L , produced by crossing-over in 69 la 



Crrr S 



r \ 



r/ 



(a cross-over from 699, q. v., 



b Pr C IIr ,. 



see above. Six wild-type daughters were tested by mating to 



b "D C 171 



b p r c s p males. Four gave the expected result for ^r " f ema l es ; 



W/r Sp 



and two (745 and 748) gave no curved offspring, so that they must 

 have been r ~ - - . 



b p r C Ur 



Females 885 to 888 contained a S' b C IIr chromosome derived 

 from the - ^ - experiments and a p r C IlT s p chromosome derived 



from a stock culture that came from culture 570 (q. v., p. 314). It is 

 quite possible that some or all of these females carried another gene 



affecting crossing-over (C///, n see below) ; but the results have 



ft 

 TABLE 19.- 



TABLE 20. 



been included because they are the only ones available for S f in the 

 presence of homozygous C n r . Other work done with C in , n makes it 

 probable that this gene would not seriously affect any region except 

 that from purple to curved; and the purple speck values for this 

 experiment agree with those from 745 and 748. Therefore the two 

 results are probably comparable. Both are included in tables 19 and 

 20 and the last line of figure 1. 



*May contain Cm, //. 



