MENDELIAN SEGREGATION 21 
11). If a vestigial gray fly is mated to a long-winged 
ebony fly, all the offspring (F,) will have long wings 
and gray (or slightly darker) body color. If these 
hybrids (F,) are inbred, offspring (F2) will be pro- 
duced in the ratios: 
9 Flies with long wings and gray body color. 
3 Flies with vestigial wings and gray body color. 
3 Flies with long wings and ebony body color. 
1 Fly with vestigial wings and ebony body color. 
In the diagram (Fig. 11) the two pairs of chro- 
mosomes that carry the genetic factors in question 
are represented by short rods. In the vestigial fly 
recessive factors for vestigial (v) are in the ‘‘second”’ 
chromosome. This same fly has two “third” chro- 
mosomes that carry only normal factors, hence a 
pair of factors normal for ebony (E). In the ebony 
fly the third chromosomes carry recessive factors for 
ebony (e), while the second chromosomes carry the 
normal factors for vestigial (V). The formule for 
the two parents are vvEE and VVee, and their 
germ cells, respectively, vE and Ve. 
The F, fly will have the composition vVEe, and 
will show neither the vestigial nor the ebony char- 
acter. It is heterozygous in each pair of factors— 
i.e. one member of the second pair of chromosomes 
carries v, the other V; similarly, for the third pair 
of chromosomes, one member carries the factor e 
and the other the normal allelomorph E. 
In the maturation of the germ cells of the hybrid, 
the members of each pair separate from each other 
as shown in Fig. 11 in the gametogenesis of Fi. 
