MEN DELI SM AND MUTATION 



337 



by T) which makes the resulting plant tall. The germ cells of the dwarf 

 plant carry something (t) causirg the dwarf condition. In the first 



PMENT5 



T T 



00 



- 00 



# m F Z 



FIG. 129. A typical Mendelian cross between tall and dwarf peas, showing dominance 

 of the tall over the dwarf condition in the first hybrid generation (Fi), and the 3: 1 ratio of 

 tall plants to dwarfs in the second hybrid generation (Ft). At the right is shown the 

 corresponding distribution of the Mendelian factors for tallness (T) and dwarf ness (t). 



hybrid generation (F\) both factors are present, T coming from one parent 



and t from the other, but T "dominates" and prevents the expression of 

 22 



