This animal has been fitted to survive
the terrible struggle in the seas by acquiring such a form that
it can lie almost unseen upon the floor of the ocean. The eye on
the under side of the body would thus be useless, but a glance at
a sole or plaice in a fishmonger's shop will show that this eye
has worked upward to the top of the head. Was the eye shifted by
the effort and straining of the fish, inherited and increased
slightly in each generation? Is the explanation rather that those
fishes in each generation survived and bred which happened from
birth to have a slight variation in that direction, though they
did not inherit the effect of the parent's effort to strain the
eye? Or ought we to regard this change of structure as brought
about by a few abrupt and considerable variations on the part of
the young? There you have the three great schools which divide
modern evolutionists: Lamarckism, Weismannism, and Mendelism (or
Mutationism). All are Darwinians. No one doubts that the
flat-fish was evolved from an ordinary fish--the flat-fish is an
ordinary fish in its youth--or that natural selection (enemies)
killed off the old and transitional types and overlooked (and so
favoured) the new.
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