STURTEVANT 



culture of this series gave two wild- 

 tvpe females, one in the first count and 

 another in the last count, ten days 

 later. These females give rise to the 

 same difficulties as did the wild-type 

 obtained in the series reported in table 

 7. One of them was tested, and gave 

 unexpected results. The mother had 



133 



carried vermilion in her forked fused 

 X, and the father had also been ver- 

 milion forked fused. The tested ex- 

 ceptional female was found to carry 

 one wild-type X and one forked fused 

 X, but did not carry vermilion at all. 

 Under the circumstances it is open to 

 question whether these two excep- 



Table 13 



tional individuals were not due to con- 

 tamination. They will be discussed 

 again later. 



Tables 12 and 13 show that bar and 

 infrabar can both be recovered from 

 bar-infrabar. It appears then that in 

 the double form the individual ele- 

 ments maintain their identity. Even 

 more important, however, is the indi- 

 cation that they maintain their se- 

 quence in the chromosome. As shown 

 in table 9, the bar-infrabar first came 



f B* 

 from the combination -5-7- , as a not- 



forked not-fused male. If the two ele- 

 ments of double forms are arranged in 



the same linear series as the rest of the 

 genes, this result must mean that the 

 bar now lies to the left of the infrabar. 

 This supposition is entirely borne out 

 by tables 12 and 13, which are experi- 

 ments of the usual type used to estab- 

 lish sequence of genes. All the 9 single 

 types recovered agree with the sup- 

 posed sequence. 



Bar-infrabar has also been tested 

 against infrabar (table 14). 



Here again there is an opportunity 

 for the production of a triple form,— 

 but since the corresponding round did 

 not appear, its absence is not signifi- 

 cant. The one double-infrabar con- 



Table 14 



BBi 



fB'fu 



5 XfBif^$ 



