132 



Isabel McCracken. 



We find upon inspection that, as in Ta*bles II and III, B X B 

 produces offspring like parents, while S X S under similar condi- 

 tions produces in part pure broods, and in part mixed broods. 



In the initial experiment, adults were isolated according to color 

 type, as already stated, as soon as color type was established or 

 in the morning succeeding the night during which adults had 

 issued. Since mating does not take place for several days after 

 the adults issue, I considered this a sufficient safeguard against 



Table X — SxS. {From SxS, Same Parentage as in Table IX.) 



mating before isolation. It has been suggested to me that the 

 possibility exists that some of the adults escaped notice until 

 mating had taken place. If this were the case, it would account 

 for the discrepancy in results between Table I, b, and Table IX. 

 While the data in Table X are recognizably insufficient, they 

 point in the same direction as results drawn from previous tables 

 of S X S matings; that is, that S X S, when presumably not far 

 removed from B progenitors produces two kinds of broods — 

 broods wholly like the parents and mixed broods. Table IX shows 

 conclusively that B X B produces offspring true to parents in the 

 first generation from similar parents, leaving the discrepancy 

 between this table and Table I to be accounted for as suggested. 



