Drosophila Melanogaster. 305 
Table V. F, generation from spineless 9 by curved <. 
Normal Normal Normal Curved 
Number wild wing spines spine- 
type spineless wingless less 
1 34 5 0 0 
2 197 43 44 11 
3 250 28 59 a 
4 253 56 56 8 
5 264 50 67 10 
6 242 66 a 12 
i 216 35 29 5 
8 50 27 11 5 
Total2.. 2... 1496 310 337 58 
The F, were made up in mass cultures July 10, 1916, transferred to new 
bottles July 16. The final count was made July 24, 1916. 
IV. Behavior of curved with vestigial. Chromosome IT. 
Vestigial, a member of group II, was described and the linkage of the gene 
reported by Morgan and Lynch. The double recessive does not appear 
among the offispring on mating the F, from a cross involving two simple re- 
cessives whose genes are allocated in the same chromosome. This is due 
to the fact that in this species there is no crossing over in the male. 
1. Vestigial 2 by curved . 
The F, from this combination had long wings typical of wild stock. Table 
V gives the different classes that appeared in the F,. 
Table VI. F, generation from vestigial 2? by curved <. 
Number Wild type Curved Vestigial 
odton Ov9 eiton Ou,9 eros eo) 2) 
1 46 32 16 13 11 9 
la 40 aD 29 26 27 26 
Total... 86 87 45 39 38 35 
*Six flies in this group were minus one eye. 
