NEW DATA. 



6l 



The same three points were combined in a different way, namely, by 

 mating forked females to bar fused males. The bar daughters were 

 back-crossed to forked fused males and gave the results shown in 

 table 42. 



TABLE 42. P l forked 9 9 X bar fused <?<?. B. C. F t bar 9 X forked 



fused cf cf . 



By combining the results of tables 41 and 42 data are obtained for 

 cross-over values from which (by balancing the inviable classes, as 

 explained in table 43) the element of inviability is reduced to a' mini- 



mum. 



TABLE 43. 



The linkages involved in these data are very strong. The cross-overs 

 between forked and bar number only 5 in a total of 1,201, which gives 

 less than 0.5 per cent of crossing-over. There are 32 cross-overs or 

 2.7 per cent between bar and fused. The value for forked fused is the 

 sum of the two other values, or 3.1 per cent. 



LINKAGE OF SABLE, RUDIMENTARY, AND FORKED. 



Rudimentary, forked, bar, and fused form a rather compact group 

 at the right end of the chromosome, as do yellow, lethal i, white, 

 abnormal, etc., at the zero end. The following two experiments were 

 made to determine more accurately the interval between rudimentary 

 and the other members of this group. A sable rudimentary forked 



