Origin of Species Variorum

→ there is no real 1869 1872

I can see no 1859 1860 1861 1866

→ to any extent slight modifications of instinct which are 1869 1872

slight modifications of instinct to any extent, 1859 1860 1861 1866

→ can be shown to have 1869 1872

has 1859 1860 1861 1866

→ though 1869 1872

but that each 1859 1860 1861 1866

→ Hornbills of Africa and India have the same extraordinary instinct of plastering up and imprisoning 1861 1866 1869 1872

male wrens (Troglodytes) of North America, build "cock-nests," to roost in, like 1859 1860

of our distinct 1859 1860

in a hole in a tree, with only a small hole left in the plaster through which the males feed them and their young when hatched: how it is that the male wrens (Troglodytes) of North America, build "cock-nests," to roost in, like the males of our distinct 1861

in a hole in a tree, with only a small hole left in the plaster through which the males feed them and their young when hatched: how it is that the male wrens (Troglodytes) of North America build "cock-nests," to roost in, like the males of our 1866

in a hole in a tree, with only a small hole left in the plaster through which the males feed them and their young when hatched; how it is that the male wrens (Troglodytes) of North America build "cock-nests," to roost in, like the males of our 1872

There- fore

Therefore

→there is no real difficulty, under changing conditions of life, in natural selection accumulating →to any extent slight modifications of instinct which are in any

useful direction.

way useful.

many

some

cases habit or use and disuse have probably come into play. I do not pretend that the facts given in this chapter strengthen in any great degree my theory; but none of the cases of difficulty, to the best of my judgment, annihilate it. On the other hand, the fact that instincts are not always absolutely perfect and are liable to mistakes;— that no instinct →can be shown to have been produced for the

exclusive

....

good of other animals, →though

animal

animals

takes

take

advantage of the instincts of others;— that the

cannon

canon

in natural history, of

"natura

"Natura

non facit

saltum"

saltum,"

is applicable to instincts as well as to corporeal structure, and is plainly explicable on the foregoing views, but is otherwise inexplicable,— all tend to corroborate the theory of natural selection.

This theory

is,

also

also,

strengthened by some few other facts in regard to instincts; as by that common case of closely allied, but

certainly

....

distinct, species, when inhabiting distant parts of the world and living under considerably different conditions of life, yet often retaining nearly the same instincts. For instance, we can

understand

understand,

on the principle of inheritance, how it is that the thrush of

South

tropical South

America lines its nest with mud, in the same peculiar manner as does our British

thrush;

thrush:

how it is that the →Hornbills of Africa and India have the same extraordinary instinct of plastering up and imprisoning the

males

females

→in a hole in a tree, with only a small hole left in the plaster through which the males feed them and the young when hatched: how it is that the male wrens (Troglodytes) of North America build "cock-nests," to roost in, like the males of our Kitty-wrens,— a habit wholly unlike that of any other known bird. Finally, it may not be a logical deduction, but