h it presents in the
skate.

In view of all these considerations taken together, I freely confess
that the difficulty presented by this case appears to me of a magnitude
and importance altogether unequalled by that of any other single
case--or any series of cases--which has hitherto been encountered by the
theory of natural selection. So that, if there were many other cases of
the like kind to be met with in nature, I should myself at once allow
that the theory of natural selection would have to be discarded. But
inasmuch as this particular case stands so far entirely by itself, and
therefore out of analogy with thousands, or even millions, of other
cases throughout the whole range of organic nature, I am constrained to
feel it more probable that the electric organ of the skate will some day
admit of being marshalled under the general law of natural selection--in
just the same way as proved to be the case with the conspicuous
colouring of those caterpillars, which, as explained in the last
chapter, at one time seemed to constitute a serious difficulty to the
theory, and yet, through a better knowledge of all the relations
involved, has now come to constitute one of the strongest witnesses in
its favour.

* * * * *

I have now stated all the objections of any importance which have
hitherto been brought against the theory of natural selection, excepting
three, which I left to be dealt with together because they form a
logically connected group. With a brief consideration of these,
therefore, I will bring this chapter to a close.

The three objections to which I allude are, (1) that a large
proportional number of specific, as well as of higher taxonomic
characters, are seemingly useless characters, and therefore do not lend
themselves to explanation by the Darwinian theory; (2) that the most
general of all specific characters--viz. cross-infertility between
allied species--cannot possibly be due to natural selection, as is
demonstrated by Darwin himself; (3) that the swamping effects of free
intercrossing must always render impossible by natural selection alone
any evolution of species in divergent (as distinguished from serial)
lines of change.

These three objections have been urged from time to time by not a few of
the most eminent botanists and zoologists of our century; and from one
point of view I cannot myself have the smallest doubt that the
objections thus advanced are not onl