The process of breaking up into the parent forms is thus continued in each successive generation, the same numerical law being followed so far as has yet been observed.
Mendel made further experiments with Pisum sativum, crossing pairs of varieties which differed from each other in two characters, and the results, though necessarily much more complex, showed that the law exhibited in the simpler case of pairs differing in respect of one character operated here also.
In the case of the union of varieties AB and ab differing in two distinct pairs of characters, A and a, B and b, of which A and B are dominant, a and b recessive, Mendel found that in the first cross-bred generation there was only one class of offspring, really AaBb.
But by reason of the dominance of one character of each pair these first crosses were hardly if at all distinguishable from AB.
By letting these AaBb’s fertilise themselves, only four classes of offspring seemed to be produced, namely,
AB
showing
both dominant characters.
Ab
"