MENDEL’S LAWS OF HEREDITY 383 
DeXRé or R?XDé . . . Parent-forms (P*) 
D(R) . . . . . Hybrid-offspring (F*) 
| : | 
3p xR. Generation of inbred hybrids (F*) 
1D + 2 D(R) 
| 
D 3D 1R R.. (F) 
| 
y + 2D(R) 
D D 3D 1R RR. (F4) 
i 
I ike D(R) | 
D DOD R R R .. (fF) 
carry with them the possibility of having offspring with the recessive 
character; that is to say, the recessive character remains latent in 
the inheritance. 
When these D(R)s are inbred (self-fertilised, in the case of peas) 
they have offspring (F,), some of which resemble the recessive parent, 
while others resemble the dominant parent, and these occur in the 
proportion of 1:3. When those resembling the recessive parent are 
inbred, they breed true—i.e., they give rise to a line of pure recessives. 
Those resembling the dominant parent are all apparently alike, but 
their subsequent history shows that they may be divided into a set 
which breed true to the dominant type and a set which behave like the 
first generation of hybrids—i.e., they go on splitting up into dominant- 
like forms and pure recessives. These two sets occur in the propor- 
tions of 1:2. 
A case of peas.—Let us consider a concrete case. Peas with 
rounded seeds were crossed with peas having angular wrinkled seeds. 
In the offspring the character of roundness was dominant; the angular 
wrinkled character had disappeared or receded. It was not Jost, as 
the next generation showed. 
The hybrid offspring, all with rounded seeds, were allowed to self- 
fertilise. In their progeny roundish seeds and angular wrinkled seeds 
occurred in the proportions of 3:1. Here were the recessives again, 
and when they were allowed to self-fertilise they produced pure reces- 
sives only, with angular wrinkled seeds. 
