130 
ered that the heterozygous normal beetles differ slightly in 
coloration from the homozygous normals, and that they could 
be distinguished without fail. The homozygous beetles have the 
black of the pronotum extending out at the base clear to the 
lateral margins, whereas in the heterozygous beetles the pro- 
notum is pale at the sides, and the femora and underparts of 
the thorax are paler (Fig. 4). Pair No. 42 of these normal 


Fig. 4. Heterozygous normal phase of Coelophora inaequalis. 
but heterozygous beetles selected from the offspring of pairs 
No. 38 and 39 produced 60 offspring of the F: generation; 
of these 47 were normal and 13 belonged to the black phase. 
On the other hand, no difference was detected between the 
homozygous nine-spotted beetles and those of the same phase 
which are heterozygous for black. 
HEREDITY OF HETEROZYGOUS NORMAL AND NINE-SPOTTED 
BEETLES IN CROSSES. 
If normal and nine-spotted beetles which are heterozygous 
for black are mated together we would expect to find segrega- 
tion of all three phases in the offspring, and that the normal 
and nine-spotted taken together, outnumber the black offspring 
about 3 to 1. We would also expect the nine-spotted and 
normal phases to be produced in about equal numbers, or pos- 
sibly with a preponderance in favor of the normal as the more 
stable phase. A cross of this kind was actually made, and 
we consequently are able to consider the outcome as expressed 
in the character of the offspring. 
The female of pair No. 37 was a heterozygous nine-spotted 
beetle raised from pair No. 35 (nine-spotted X black), and the 
