( jizxi )) 
recessive. According to Mendel’s hypothesis recessives when 
paired together must always breed true, and accordingly in 
Mr. Prout’s experiments in every case when black was mated 
with black, exclusively black offspring were produced, even 
when the black parents had purple ancestry. The dominant 
purple form, on the other hand, may contain the recessive 
character, and if so half the germ-cells which it produces will 
bear purple, the other half black. If such an insect is paired 
with a black, which by hypothesis must be pure, then half the 
offspring will be black (pure) and half will be purple hybrids. 
In matings of this kind Mr. Prout obtained 171 black, 147 
purple and 4 intermediate, where the Mendelian expectation 
is 161 black and 161 purple. The rare intermediates must be 
regarded as cases in which the dominance of the purple is not 
quite complete, and the numbers (roughly 53 per cent. and 47 
per cent.) are not far from the expected equality of the two 
forms. 
“Tf the purple is dominant, when purple is mated with purple 
either all the offspring will be purple (if one or both of the 
parents are pure dominants), or there will be three purples to 
one black (75 per cent. to 25 per cent.), if both contain the 
recessive character. In all Mr. Prout’s matings the latter 
case was observed, for black occurred in each family. Alto- 
gether, including the family described as (1) on p. 529, there 
were obtained 147 purple, 2 intermediate, 60 black where the 
Mendelian expectation is 157 purple, 52 black, 7. e. Mr. Prout 
obtained about 71 per cent. and 29 per cent. instead of the 
expected 75 and 25 per cent. 
‘“‘It is perhaps remarkable that among ten pairings of this 
nature none should have been pure dominants, but as most of 
the insects used were the progeny of wild purples, and black is 
admittedly the commoner form in nature, this need cause no 
surprise. That the recessive form is the commoner in the 
wild state is not rare, e.g. I have shown that the common 
form of Angerona prunaria is recessive to the var. sordiata 
(P. Z.S. 1906, vol.I, p. 125), and other cases might be added. 
I think it must be concluded therefore that instead of showing 
that the two colour-forms of X. ferrugata are not inherited 
in accordance with Mendel’s Law, Mr. Prout’s experiments 
