_ 
134 
male a heterozygous normal beetle from pair No. 34 (normal 
X black). A total of 59 beetles were raised from this pair, 
of which 14 were normal, 28 nine-spotted, and 17 black. 
The blacks were produced, therefore, in true Mendelian pro- 
portion, but there was an unexpected preponderance of the 
nine-spotted over the normal. 
If the ancestry of pair No. 37 be examined, the nine- 
spotted phase will be found greatly in the ascendency, the 
direct female line of descent having been nine-spotted for five 
preceding generations, and the direct male line also nine-spotted 
for the first four generations. This, perhaps, is the true ex- 
planation of the predominance of the nine-spotted phase in the 
offspring of this pair. 
NINE-SPOTTED PHASE MorRE STABLE WHEN CrosSSED WITH 
THE BLACK. 
But, on the other hand, when the nine-spotted phase is 
crossed with the black, as in pairs Nos. 16, 17 and 35, and in 
pairs Nos. 19, 20, and 22 of the F: generation, the nine-spotted 
phase is evidently stabilized, as from these pairs as many as 
seventy nine-spotted offspring were reared without the appear- 
ance of the normal phase except in one instance which may 
have been due to a mixture of lots. In crosses between heter- 
ozygous, and presumably homozygous nine-spotted beetles, a 
large percentage of the offspring were nine-spotted. The data 
on these crosses may be conveniently tabulated: 
Pair Female Male Character Character of 
No, from from of parents offspring 
black X 
15 No. 10 9-spotted No. 5 normal 9-spotted 7 9-spotted 4 normal 
black X black X 
23 No.17 9 spotted No. 18 9-spotted %-Spotted 14 9-spotted 1 normal 
black X 
26 No.18 9-spotted No.16 9-spottea %-Spotted 
bo 
9-spotted 0 normal 
black X 
28 No.12 9-spotted No.16 9 spotted 9-Spotted 19 9-spotted 6 normal 
29 No.15 9-spotted No. 17 Rene ier 9-spotted 14 9-spotted 4 normal 
36 No. 22 9-spotted No. 23 9-spotted 9-spotted 19 9-spotted 4 normal 
Totals 75 9-spotted 19 normal 
There is some evidence, therefore, that the nine-spotted 
phase is given greater stability when crossed with the black, 
