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the face of an exuberant life, the ideally-armed robber must be
satisfied with the off-fall of that life.”—(ftp. 6gg-yoo.)
“ We see in our forests the societies formed by the young nut-
catchers (Sitta cæsia), together with titmouses, chaffinches, wrens,
tree-creepers, or some woodpeckers. In Spain the swallow is met
with in company with kestrels, flycatchers, and even pigeons. In
the far West the young horned larks live in large societies, together
with another lark (Sprague’s), the skylark, the Savannah sparrow, and
several species of buntings and longspurs. In fact it would be much
easier to describe the species which live isolated than to simply name
those species which join the autumnal societies of young birds,
not for hunting or nesting purposes, but simply to enjoy life in society
and to spend their time in plays and sports, after having given a few
hours every day to find their daily food.”—(ft. yoi.)
“ The quagga zebra . . . lives on excellent terms not only with
ostriches but also with gazelles, several species of antelopes, and
gnus—i.e., it lives together with ruminants feeding on the same
grass as itself.”—(ft. yoy—note.)
As the result of this co-operation it will sometimes
happen that the best and fittest to live will perish in
the act of defending the flock or herd to which they
belong. But however this may be, it is quite clear that
co-operation will prevent the sole survival of the fittest.
The advocate of Natural Selection argues consistently
with his theory that the improvement of the race is
secured by the severity of the struggle between individuals
of the same species. Weismann puts the case with
admirable clearness.
“ In order that any part of the body of an individual of any
species may be kept at the maximum degree of development, it is
necessary that all individuals possessing it in a less perfect form must
be prevented from propagation—they must succumb in the struggle
for existence. I will illustrate this by a special instance. In species
which, like the birds of prey, depend for food upon the acuteness
of their vision, all individuals with relatively weak eyesight must
be exterminated, because they will fail in the competition for food.
Such birds will perish before they have reproduced themselves,
and their imperfect vision is not further transmitted. In this way
the keen eyesight of birds of prey is kept up to its maximum.”—
(Weismann. Essays, ft. agi.)