Mendel has given a very
suggestive and simple explanation of his formula. Putting this in the
terminology of to-day, and limiting it to the occurrence of only [295]
one differential unit in the parents, we may give it in the following
manner. In fertilization, the characters of both parents are not
uniformly mixed, but remain separated though most intimately combined in
the hybrid throughout life. They are so combined as to work together
nearly always, and to have nearly equal influence on all the processes
of the whole individual evolution. But when the time arrives to produce
progeny, or rather to produce the sexual cells through the combination
of which the offspring arises, the two parental characters leave each
other, and enter separately into the sexual cells. From this it may be
seen that one-half of the pollen-cells will have the quality of one
parent, and the other the quality of the other. And the same holds good
for [296] the egg-cells. Obviously the qualities lie latent in the
pollen and in the egg, but ready to be evolved after fertilization has
taken place.
Granting these premises, we may now ask as to the results of the
fertilization of hybrids, when this is brought about by their own
pollen. We assume that numerous pollen grains fertilize numerous egg
cells.
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