Drosophila Melanogaster. 303 
This cross should give a ratio of 9:3:3:1 if the gene for curved is in 
a chromosome other than IV. Bent is a poor character with which to con- 
trast curved since both characters involve the wings and the double re- 
cessive cannot with certainty be distinguished. A few forms appeared, 
however, which I took to be curved bent. Counting the double recessive 
with curved and bent a ratio of 9 to 7 should result. The table gives 
approximately this ratio and a tentative conclusion reached that the gene 
for curved is borne by a chromosome which gives free assortment with IV. 
ITI, Behavior of curved with spineless. Chromosome IIT, 
1. Curved 2 by spineless . 
Spineless, a mutant characterized by the absence of bristles on the thorax, 
was first described by Bridges. Its gene belongs to Chromosome III. All 
children from the curved 9 by spineless ., were characteristic of the wild 
type. These when inbred in pairs gave in the F, generation the different 
classes as shown in table III. 
Table III. F, generation from-curved 2 by spineless <. 
Number Normal Normal | Curved 
of Wild wing spines Spineless 
Mating type spineless curved 
1 75 21 22 5 
2 57 14 la 4 
3 57 17 19 8 
4 58 18 13 8 
5 89 16 22 He 
6 58 15 14 4 
7 61 22 13 5 
8 9 2 2 0 
9 39 14 8 4 
10 55 1 11 1 
11 42 2 12 0 
12 Wa 24 20 10 
13 63 2 14 0 
14 oD 9 9 4 
15 82 25 24 5 
16 46 13 14 6 
17 78 20 18 8 
18 87 25 28 8 
19 49 1 24 0) 
20 48 11 14 5 
21 60 23 14 4 
22 48 18 8 4 
23 40 2 13 0 
24 47 17 13 1 
EOtalet cs. 1360 332 360 96 
