26 



SEX-LINKED INHERITANCE IN DROSOPHILA. 



The locus of rudimentary is at 55.1, for a longtime the extreme right 

 end of the known chromosome, though recently several mutants have 

 been found to lie somewhat beyond it. 



FIG. A. a, rudimentary wing; b, the wild fly for comparison. 



The rudimentary males are perfectly fertile, but the rudimentary 

 females rarely produce any offspring at all, and then only a very few. 

 The reason for this is that most of the germ-cells cease their develop- 

 ment in the early growth stage of the eggs (Morgan, 19150). 



MINIATURE. 



(Plate II, figures 7 and 8.) 



The recessive sex-linked mutant miniature wings appeared in August 

 1910 (Morgan, 191 ib and 19120). The viability of miniature is fair, 

 and this stock has been used in linkage experiments more than any 



