Nor
can I see reason to doubt that the widely different habits of life of
men and women in civilised nations, especially amongst the upper
classes, would tend to counterbalance any evil from marriages between
healthy and somewhat closely related persons.
Under a theoretical point of view it is some gain to science to know
that numberless structures in hermaphrodite plants, and probably in
hermaphrodite animals, are special adaptations for securing an
occasional cross between two individuals; and that the advantages from
such a cross depend altogether on the beings which are united, or their
progenitors, having had their sexual elements somewhat differentiated,
so that the embryo is benefited in the same manner as is a mature plant
or animal by a slight change in its conditions of life, although in a
much higher degree.
Another and more important result may be deduced from my observations.
Eggs and seeds are highly serviceable as a means of dissemination, but
we now know that fertile eggs can be produced without the aid of the
male. There are also many other methods by which organisms can be
propagated asexually. Why then have the two sexes been developed, and
why do males exist which cannot themselves produce offspring? The answer
lies, as I can hardly doubt, in the great good which is derived from the
fusion of two somewhat differentiated individuals; and with the
exception of the lowest organisms this is possible only by means of the
sexual elements, these consisting of cells separated from the body,
containing the germs of every part, and capable of being fused
completely together.
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