CROSSINGOVER IN DROSOPHILA 



159 



fertile females would hatch. Because of the large amount of 

 labor involved, it was obviously impossible to run these all at 

 the same time, or to secure offspring from the same Pi parents. 

 Equal care was used in all the tests, however, and careful con- 

 trols were run with each set. With one exception — No. 6 .in 

 the table — the mutant stock used was black-purple-curved, and 



27 29 31 33 35 37 39 41 43 45 47 49 61 crossing over 



15 17 19 21 23 25 27 29 31 33 35 37 39 41 ^^^l** 



Fig. 2. Percentages of crossingover, for both regions of the bottle counts 

 summarized in table 7 — plotted to show variation (cf. Appendix). — 

 trols; =9 parents hatched at 31.5°. 



= con- 



