onstant struggle for existence; because while the
offspring always exceeds the parents in number, generally to an
enormous extent, yet the total number of living organisms in the world
docs not, and can not, increase year by year. Consequently every year,
on the average, as many die as are born, plants as well as animals;
and the majority die premature deaths. They kill each other in a
thousand different ways; they starve each other by some consuming the
food that others want; they are destroyed largely by the powers of
Nature--by cold and heat, by rain and storm, by flood and fire. There is
thus a perpetual struggle among them which shall live and which shall
die; and this struggle is tremendously severe, because so few can
possibly remain alive--one in five, one in ten, often only one in a
hundred or even in a thousand.

"Then comes the question, Why do some live rather than others? If all
the individuals of each species were exactly alike in every respect, we
could only say it is a matter of chance. But they are not alike. We find
that they vary in many different ways. Some are stronger, some swifter,
some hardier in constitution, some more cunning. An obscure color may
render concealment more easy for some, keener sight may enable others to
discover prey or escape from an enemy better than their fellows. Among
plants the smallest differences may be useful or the reverse. The
earliest and strongest shoots may escape the slug; their greater vigor
may enable them to flower and seed earlier in a wet autumn; plants best
armed with spines or hairs may escape being devoured; those whose
flowers are most conspicuous may be soonest fertilized by insects. We
can not doubt that, on the whole, any beneficial variations will give
the possessors of it a greater probability of living through the
tremendous ordeal they have to undergo. There may be something left to
chance, but on the whole _the fittest will survive." (_"Darwinism"_
p. 7)_.

The same writer gives a probable instance of the working of _Natural
Selection_ in the origin of certain aquatic birds called dippers. He
says: "An excellent example of how a limited group of species has been
able to maintain itself by adaptation to one of these 'vacant places' in
Nature, is afforded by the curious little birds called dippers or
water-ouzels, forming the genus _Cinclus_ and the family _Cindidae_ of
naturalists. These birds are something like small thrushes, with very
short wi