3. 



A. H. Trow 285 



A B C d e f 



DC 



a b c D E F 



A B C D e f 



DC 



B 



5. 



Frutn these figures we can see that the cross-overs in which A is 

 concerned are as follows : 



According to this scheme the cross-overs appear to occur in nuiubcis 

 exactly proportional to the distance apart of the fiictors concerned. For 

 example, F is five units from A, D three units, and B one unit. Af 

 occurs five times, and Ad three times as often as Ah. This is not 

 exactly obvious until it has been worked out, but my mathematical 

 colleagues agree with me that it is perfectly true. This is doubtless 

 the mathematical basis upon which the hypothesis of the localization 

 of the factors has been built up. We have however to note that the 

 essence of the scheme consists in determining the ratio between cross- 

 overs and non-cross-overs. An examination of the figures will show 

 that we get the following relationships : 



