104 



THE AMERICAN NATURALIST [Vol. XLIX 



in pairs, and transferred during a period of twenty days 

 (May 16- June 4) 13 times, remaining in each bottle from 

 one to two days. Care was taken to count every fly of the 

 F 2 that hatched. The result follows: 



TABLE VI 



Eecoed op F 2 Flies Which Hatched from Eggs Deposited During a 

 Period of 20 Days; During Which Time the Parents Were 

 Transferred Thirteen Times 









v| ass 













d> 



D 



j:r, l'()<> 



HiJ |,;s 

 202 119 



5 



i I 



19 | 9.7 



1 



b 105 | 108 



c 189 153 



d 5 .... 70 58 



52 



37 



3.2 

 1.5 



1 



1 

 1 



Here we have a group in which the pink ran sometimes 

 relatively ahead of the red. But the other extreme is also 

 represented in pairs D and d. The numbers obtained are 

 in each case large enough to be significant. 



This experiment was repeated on a larger scale in the 

 fall of 1912. Ten pairs were used for each of these 

 crosses and they were continually transferred as long 

 as they lived. The records follow : 



TABLE VII 



F a Record from Red-eyed Flies Crossed to Pink-eyed Flies Mated in 

 Pairs. Showing the Total Output of Each F, Pair 

 During its Lifetime 



Pink $ x Red 6* -> in F 2 



218 218 79 73 

 476 435 U 

 259 248 83 89 

 392 39G 152 1 

 864 805 258 2 

 357 35S 130 124 715 254 



