102 THE THEORY OF THE GENE 



probably be explained on the assumption that a large 

 section of this chromosome has been reversed, and the 

 corresponding loci are in inverse order. 



These results of Sturtevant's are not only important 

 in themselves, but help to make probable the view that 

 similar mutants in different species that occupy the same 

 relative position in the linkage series, are identical mu- 

 tants, but unless their identity can be tested by crossing, 



I 

 0.0-f se 



0.6- -ij 



27.0 

 30.0 



450--SI 



57.0 



66.0 

 70.0 



78.0 -- 



,C 

 v 



vs 



m 

 f 



s 

 tr 



"T.g.W 



102.04- dr 



n m 



0.0+ cf 0.0-t-Sc 



• d 



42.0 4- Cc 



41.0 



62.0 --t 



.-hch 



h P 



D. virilis 



o.o-t-Fu.ap I 



-- 1 



21.0 --Br 





Fig. 60. 



Chart of the location of the mutant genes in the six chromosomes 

 of Drosophila virilis. (After Metz and Weinstein.) 



