No. 578] DBOSOPHILA AMPELOPHILA 



L15 



The fact that it has been found possible by proper 

 manipulation to get a group in which the ratio fluctuated 

 in one direction only, even if it was not as marked as was 

 hoped it would be, indicates that the disturbance is due to 

 an internal, and not to an external, cause. This was 

 further emphasized by the distinct tendency for segrega- 

 tion, as was to be expected if there were some hetero- 

 zygous individuals. It was also suggested in another 

 way. No matter how short-lived or how long-lived a pair 

 was; whether it was transferred once, twice, or even 

 twenty times, the ratio of red to pink did not vary 

 throughout its life when the yields of the several bottles 

 were compared with one another. 



TABLE XVIII 

 F 2 of Four Pairs (A, B, C ai 

 2?) Bed ? X Pink J in Which 

 the Males Were Crossed 



TABLE XIX 



Table XVIII 

 Expectations:! 



Expectation 1:1 



