Origin of Species Variorum

→ structure of the animal to 1869 1872

animal, by some modification of its structure, for 1859 1860 1861 1866

→ It is, however, 1869 1872

But it is 1859 1860 1861 1866

→ into it like 1866 1869 1872

like 1859 1860 1861

↑ 1 blocks not present in 1860 1861 1866 1869 1872; present in 1859

Even in so extreme a case as this, if the supply of insects were constant, and if better adapted competitors did not already exist in the country, I can see no difficulty in a race of bears being rendered, by natural selection, more and more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale.

→ OMIT 1872

of a species 1859 1860 1861 1866 1869

→ proper to their 1872

both of their own 1859

of their own 1860 1861 1866 1869

→ OMIT 1869 1872

on my theory, 1859 1860 1861 1866

→ (Colaptes campestris) which has two toes before and two behind, a long pointed tongue, pointed tail-feathers, sufficiently stiff to support the bird in a vertical position on a post, but not so stiff as 1872

which in every essential part of its organisation, even in its colouring, 1859 1860

( Colaptes campestris ) which has two toes before and two behind, a long pointed tongue, stiff pointed tail feathers, but not so stiff as 1861

( Colaptes campestris ) which has two toes before and two behind, a long pointed tongue, stiff pointed tail-feathers, but not so stiff as 1866

( Colaptes campestris ) which has two toes before and two behind, a long pointed tongue, pointed tail-feathers, sufficiently stiff to support the bird in a vertical position on a post, but not so stiff as 1869

→ typical woodpeckers, and a straight strong beak. 1869 1872

harsh tone of its voice, and undulatory flight, told me plainly of its close blood-relationship to our common species; yet it is a woodpecker which never climbs a tree! 1859 1860

typical woodpeckers (yet I have seen it use its tail when alighting vertically on a post), and a straight strong beak. 1861 1866

had come to a high stage of perfection, so as to have given them a decided advantage over other animals in the battle for life. Hence the chance of discovering species with transitional grades of structure in a fossil condition will always be less, from their having existed in lesser numbers, than in the case of species with fully developed structures.

I will now give two or three instances

both of

diversified and of changed habits in the individuals of the same species.

When

either case

occurs,

....

it would be easy for natural selection to

fit

adapt

the →structure of the animal to its changed habits, or exclusively

for

one of its several

different

....

habits. →It is, however, difficult to

tell,

decide,

and immaterial for us, whether habits generally change first and structure afterwards; or whether slight modifications of structure lead to changed habits; both probably often

change

occurring

almost simultaneously. Of cases of changed habits it will suffice merely to allude to that of the many British insects which now feed on exotic plants, or exclusively on artificial substances. Of diversified habits innumerable instances could be given: I have often watched a tyrant flycatcher (Saurophagus sulphuratus) in South America, hovering over one spot and then proceeding to another, like a kestrel, and at other times standing stationary on the margin of water, and then dashing →into it like a kingfisher at a fish. In our own country the larger titmouse (Parus major) may be seen climbing branches, almost like a creeper; it

often,

sometimes,

like a shrike, kills small birds by blows on the head; and I have many times seen and heard it hammering the seeds of the yew on a branch, and thus breaking them like a nuthatch. In North America the black bear was seen by Hearne swimming for hours with widely open mouth, thus catching,

almost like

a whale, insects in the water. ↑

As we sometimes see individuals →OMIT following habits

widely

....

different from those →proper to their species and

the other species of the same genus, we might

expect,

expect

→OMIT that such individuals would occasionally

have

....

given

give

rise to new species, having anomalous habits, and with their structure either slightly or considerably modified from that of their

proper

....

type. And such instances

....

occur in nature. Can a more striking instance of adaptation be given than that of a woodpecker for climbing trees and

for

....

seizing insects in the chinks of the bark? Yet in North America there are woodpeckers which feed largely on fruit, and others with elongated wings which chase insects on the

wing;

wing.

and on

the plains of La Plata, where

not

hardly

a tree grows, there is a

woodpecker,

woodpecker

→(Colaptes campestris) which has two toes before and two behind, a long pointed tongue, pointed tail-feathers, sufficiently stiff to support the bird in a vertical position on a post, but not so stiff as in the →typical woodpeckers, and a straight strong beak.