MENDEL’S DISCOVERIES 541 
spect to tallness and dwarfness and the facts carefully recorded. 
The individuals of the F, generation were allowed to self-ferti- 
lize, and from the seeds obtained the F; generation was grown, 
and the individuals in this generation were studied in the same 
careful way as those of the previous generations. Throughout 
a number of generations the behavior of tallness and dwarfness 
was carefully recorded. In this way he studied many pairs of 
characters such as: (1) shape of pod (whether simply inflated 
or deeply constricted between the seeds); (2) color of unripe 
pod (whether green or yellow); (3) distribution of flowers on 
the stem (whether distributed along the axis of the plant or 
bunched at the top); (4) color of cotyledons (whether yellow 
or green); (5) shape of seeds (whether round or wrinkled); 
and (6) color of seed coat (whether gray or brown, with or 
without violet spots, or white). 
Mendel’s Discoveries. — Mendel found that in most cases the 
different pairs of characters investigated behaved in the same 
way and appeared in a regular way in the successive generations. 
Furthermore, it made no difference as to which variety was used 
as the mother parent. In case of tallness and dwarfness, all the 
plants of the first or F; generation were tall. They were all like 
the tall parent. In the second or F2 generation there were both 
tall and dwarf plants, but there were three times as many tall 
plants as dwarf ones, the talls and the dwarfs thus occurring 
in the ratio of 3:1. The offspring of the dwarfs were all dwarfs 
in the third or F; generation and in all‘ succeeding generations. 
The dwarfs, therefore, were pure for dwarfness, that is, they 
had no factors or genes for tallness in them. One out of every 
three tall plants also bred true and, therefore, proved to be 
pure for tallness, but two out of every three tall ones gave three 
times as many tall ones as dwarfs or a ratio of 3 : 1, thus being 
apparently the same in constitution as each of the individuals of 
the F, generation. They evidently contained factors or genes 
for both tallness and dwarfness. The dwarfs and one-third of 
the tall ones of the F; progeny bred true, while two-thirds of 
the tall ones again bred as in the previous generation, giving the 
ratio 3:1, and two-thirds of the tall ones being impure. This 
proved to be a constant way of behaving throughout genera- 
tions The character of the individuals of the different gen- 
erations are shown in Figure 475. Thus by the further breed- 
