SEX-LINKED INHERITANCE IN DROSOPHILA 



39 



GENERAL CONCLUSIONS 



It is not our intention to discuss here the many questions that 

 arise in connection with these results, but rather to put the 

 data on record for future reference. There are three topics, 

 however, that require summing up: 



1. The total record of crossing-over for the combination YW 

 and BR and the reciprocal. 



2. The total record of crossing-over for LW and SR and the 

 reciprocal. 



3. The record of crossing-over for LY and SR and the recip- 

 rocal. 



In all three are six records of crossing over of YW and BR. 

 The simplest cases are those in which both parents have long 

 wings. We have Dexter's large count, counts in two pre- 

 ceding papers (Morgan '11, Morgan and Cattell '12) and the 

 counts of the present paper. 



In these counts, the second in the table gave anomalous results, 

 the cross-overs falling below the other cases. The last three 

 cases contain brown which has a high mortality; yet the total 

 result is not far from Dexter's results. In the next table the 

 results are complicated by the presence of short wings, which 

 run behind long wings in some combinations, particularly where 

 short, yellow, white is expected. 



