318 



INHERITED LINKAGE VARIATIONS 



in this same direction (Bridges, 1915; Plough, 1917), the decrease is 

 probably significant. More exact methods (see Plough, 1917) are 

 necessary for obtaining clear-cut data on this point, as has already 

 been stated. 



Here, as also in the case of C//,, wherever reliable information 

 regarding coincidence is available, the value is not far from the one 

 found in females that contain neither Qm nor C//,. (see Bridges 



Cm 



Table 15. 



Cii, 



Loci. 



S' b Pr c Sp 



b PtC 



b Pt c mr 



Second cultures 



S' b Pr c Sp . 



Table 16. — 



Cn 



Cllr 



and Morgan, 1919). But in no case does this include a region in the 

 "sphere of influence" of the cross-over gene present; for in all such 

 regions the percentage of crossing-over is too small to give statistically 



reliable results. 



Cii I 



Cii, 



Pr 



Cultures 677 and 678 both contained females, 7^ 7^ — (678 was 



also heterozygous for m,), mated to 6 p^ c males. A cross-over female, 



