A Modification of the Sex Ratio, and of other Ratios, etc. 



337 



time the explanation of the results was not known, although the 

 suspicion soon arose that they were due to linkage between the sex- 

 linked wing factors. This has proved to be the case. These earlier 

 observations were carried through as many as eight generations, and 

 the ratios in question were found to recur. I have not thought it 

 worth while to give these results entire — only a few samples of 

 them have been furnished — because they are merely repetitions over 

 and over again of the same relations; moreover, the mass culture 

 used was not strictly guarded against mating before separation (see 

 below). In consequence the results were often confusing and this is 

 apparent also in the examples I gave in my prehminary note. The 

 data there cited show in the main the relations they were intended 

 to show, but a few extra classes appeared that were not consistent, 

 and these, as I now know, were due to accidental matings before 

 isolation. 



In order to obtain new and indisputable data concerning the 

 unusual sex-ratio in long-winged F2 flies, the original cross was 

 repeated under carefully controlled conditions. 



When a rudimentary winged male was mated to a miniature 

 female all the F^ females had long wings and the males, miniature 

 wings. These inbred gave the following results: 



Long 9 2216 Long rj 401 Min. 9 1969 llin. (5 1617 Rud. cj 781 Rud.-min. cj 184 



The long-winged males (401) are only about one-fifth as numerous 

 as the long-winged females, while the miniature males nearly equal 

 the miniature females. 



The analysis of this result has already been given on page 329 

 but in order to get the facts before us again it may be repeated here: 



Min. 9 rMX — rMX 



Rud. (5 RmX — rm 



I rMXRmX = Long 9 



* \ r.MXrm = Min. (J 



RMX — rMX — RmX — rmX Eggs 



rMX — rm Sperm 



RMXrMX = Long 9 

 rMXrMX = Min. 9 

 RmXrMX = Long 9 

 rmXrMX = Min. 9 

 RMXrm = Long (J 

 rmXrm = Min. (J 

 RmXrm = Rud. cJ 

 rmXrm = Rud.-min. (J 



Gametes of Fj 



