SEX-LINKED LETHALS IN DROSOPHILA 



113 



In table 23 the data for the male classes available in the pre- 

 ceding tables are brought together in the first four columns. 

 In the four columns that follow these, the percentages of cross- 

 ing-over between: (1) eosin and lethal; (2) lethal and minia- 

 ture; (3) eosin and miniature, are calculated for each of the 

 experiments taken separately and for the sum total of the data.^ 



There is a considerable amount of difference in the percentages 

 from the different experiments, as an examination of the table 

 will show. If we take the totals as the more significant it ap- 

 pears that Lethal ii lies nearly midway between eosin and minia- 

 ture, but nearer to eosin. The total 'distance,' viz., 25 between 

 eosin and miniature is smaller than that calculated from other 

 data. 



In the preceding experiments the females as well as the males 

 give significant figures for eosin and miniature. In the next 

 table, 24, these are brought together, and the percentage of 

 crossing over between eosin and miniature calculated. This is 

 30.7 per cent. 



In order to see whether the lethal factor has itself any influence 

 on the results (which is not to be expected), the data from the 

 sister individuals that gave a 1 :1 ratio have also been utilized and 

 are given in table 25. The percentage 'distance' is 32.4, which 

 agrees with the calculation for the totals of the preceding table. 

 Finally, the female classes alone are taken in the 2 :1 count. These 



^ The data in two cases, viz., 15a and 15b are not calculated separately, since 

 the numbers are small. 



