132 
and this may be the explanation of the preponderance of the 
nine-spotted phase in the offspring of pair No. 37. We have 
also already seen that in crosses between the nine-spotted and 
the normal phase there is a distinct tendency for the former 
to be gradually eliminated, as it is less stable than the normal. 
lf it is true that the nine-spotted phase is constantly stabilized 
by crosses with the black, the one tendency counteracts the 
other, and the nine-spotted phase is thus able to maintain itself 
under natural conditions. 
HEREDITY OF HETEROZYGOUS BEETLES CROSSED WITH BLACK. 
In crosses where one parent is recessive and the other 
heterozygous, the offspring should be produced in the ratio of 
one recessive to every dominant. ‘Two crosses of this nature 
were made and produced results given here in tabular form: 
Pair Female Male 
No from from Character of parents Character of offspring 
; ; - 1 l 
4) pNo.258 No.200 | Vie eee ats | 41 ao sblatcixjansa) Seepobted 
eter lf 
Als) DNou34¢y Ney20 et eo uecus ermal feuiale) eeipluck 4 /25enormel 
We thus observe that the expected proportion of the phases 
was nearly perfectly attained in the offspring. 
HEREDITY OF THE BLACK PHASE CROSSED WITH BLACK. 
As the last link in the chain of evidence to prove that the 
black phase is a simple Mendelian recessive, the cross was 
made of black with black, using a female reared from pair 
No. 38, and a male from pair No. 39. From this union (pair 
No. 43) were reared a total of sixty-two beetles, all of which 
were black like the parents, showing that the black phase 
breeds true to itself as a recessive should. 
CONCLUSIONS. 
From the data now presented to you it is evident that the 
black phase of Coelophora inaequalis is a Mendelian recessive 
to the dominant normal and nine-spotted phases, that it breeds 
true to itself, and when crossed with either of the dominant 
forms is produced in Mendelian proportions in alternate 
generations. 
The relationship of the normal and nine-spotted phases is 
