HEREDITY 75 
mice, and rabbits. In its simplest expression the law may 
be stated as follows :—If A be a well-established, pure-bred 
variety with a certain character, e.g. of stature or colour, 
and # be another well-established variety in which the 
corresponding character is different, and if A and & are 
crossed, the hybrid offspring (4) will usually resemble one 
of the parents in the particular distinguishing character. 
The character which finds expression is called the dominant ; 
the character which remains latent in the hybrids is called 
the recessive. Now, if the hybrids are bred together, their 
descendants will be of two kinds, some like the dominant 
grandparent, some like the recessive grandparent. When 
those like the recessive grandparent are in-bred, they yield 
only recessives. When those like the dominant grand- 
parent are in-bred, some yield pure dominants only—that 
is, forms which if in-bred yield only dominants ; but others 
yield apparent dominants like the original hybrid—that is, 
with the power of throwing off when in-bred more pure 
dominants, more pure recessives, and more apparent 
dominants like the original hybrid. The results tend to 
be always in the proportion 14+2A (B)+1B, as regards 
the two contrasted characters of A and B. 
Two diagrams (after T. H. Morgan and R. C. Punnett) 
may make the matter clearer. 
A B 
A (B) 
io" s Re 
1A 2A (B) 1B 
