194 MENDELISM 
allelomorph respectively, since half the offspring ob- 
tained on mating the blue birds with black are black, 
and half the offspring obtained on mating them with 
splashed white are splashed white. The following 
scheme of inheritance illustrates the phenomena 
described : 
1 (zygote) blue heterozygote 
I (gametes) black and white 
| | | 
2 (zygote) 1 black-black 2 black-white 1 white-white 
(blue heterozygote) 
2 (gametes) black black white 
black white white 
| | . | 
| 
3 (zygote) black black 2blue 1white white 
black white 
5 (gametes) black a white 
4 (zygote) all blue heterozygotes 
A case which is closely similar to that of the An- 
dalusian fowl is afforded by the cross between Primula 
sinensis and Primula stellata. 
P. sinensis crossed with P. stellata gives rise to a 
type which is different from either parent, being in 
some respects intermediate between the two. The 
hybrid is so distinct that a special name has been given 
to it, and the new type is known as P. pyramidalis. 
So far it has been found impossible to obtain a strain 
of P. pyramidalis which will breed true. On self- 
fertilization the offspring are found to show the types 
