250 



THE AMERICAN NATURALIST [Vol. XLIS 



infertility of the rudimentary females is due, largely at 

 any rate, to their retention of their eggs, even after copu- 

 lation; and since in a few cases rudimentary females and 

 males bred together have produced daughters as well as 

 sons, the hypothesis of prematuration that I suggested in 

 1912 is not the correct explanation of the sterility of the 

 females of the rudimentary winged stock mated to rudi- 

 mentary males. Moreover, since many of the females 

 tested, especially in the later experiments, were F 2 's ex- 

 tracted through other fertile stocks, the sterility can not 

 be supposed to be due to any additional peculiarity that 

 has appeared in the rudimentary stock, but must be one of 

 the attributes of the factor for rudimentary itself. 



