Origin of Species Variorum

→ I can see no 1859 1860 1861 1866

there is no real 1869 1872

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

to any extent slight modifications of instinct which are 1869 1872

→ has 1859 1860 1861 1866

can be shown to have 1869 1872

→ but that each 1859 1860 1861 1866

though 1869 1872

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

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

→ 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 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 1869

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

instincts

stincts

vary slightly in a state of nature. No one will dispute that instincts are of the highest importance to each animal.

There- fore

Therefore

→I can see no difficulty, under changing conditions of life, in natural selection accumulating →slight modifications of instinct to any extent, in any

way useful.

useful direction.

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 →has been produced for the

~~exclusive~~

exclusive

good of other animals, →but that each

animals

animal

take

takes

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~~

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

tropical South

South

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

thrush;

thrush:

how it is that the →male wrens (Troglodytes) of North America, build "cock-nests," to roost in, like the

females

males

→of our distinct Kitty-wrens,— a habit wholly unlike that of any other known bird. Finally, it may not be a logical deduction, but to my imagination it is far more satisfactory to look at such instincts as the young