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, 1915^). 



MINIATURE. 



(Plate II, figures 7 and 8.) 



The recessive sex-linked mutant miniature wings appeared in August 

 1910 (Morgan, i<)iib and 1912a). The viability of miniature is fair, 

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



