Hybridization and Crossbreeding 275 
When fertilization has taken place, the petals of the 
flowers, as a rule, drop off. They generally act as an 
attraction for insects to visit the flowers. 1 hese insects 
carry away some of the pollen and deposit it on the stigma 
of the next flower they visit, effecting pollination in a natural 
way. Therefore, after fertilization, the petals are ot no 
further use to the plant, 
and are cast off. 
As a result of fertil- 
ization, and the formation 
of the embryo and endo- 
sperm — the store cells 
for food materials — we 
oret the seed. 
o 
Now we see at once 
how the qualities of the 
two parent plants are in- 
corporated in the seed 
which results from cross- 
fertilization. The nucleus 
of the pollen grain, with 
its inherent qualities, 
unites with the nucleus of 
the embryo sac, thus combining, in the closest way possible, 
the qualities of both plants. When the seed is sown, how- 
ever, we must not expect to get plants with all the good 
qualities of both parents, or even to get plants with the 
greater proportion of the good qualities of both. We often 
get something quite different from what we expect. We 
must go on again and again, and cross those plants with 
the best qualities, until we get what we desire, or as near 
Changes in the Protoplasm of the Cell-nucleus 
during Cell Division 
