Origin of Species Variorum

→ which 1872

acting either consciously or unconsciously, 1866 1869

→ directions; and it is this latter agency which answers to the survival of the fittest under nature. 1872

directions. 1866

directions, and this answers to the survival of the fittest under nature. 1869

→ the increased Use and Disuse of Parts, as controlled by Natural Selection . 1872

Use and Disuse .— 1859 1860 1861

Use and Disuse, as controlled by Natural Selection. 1866

Use and Disuse, as controlled by Natural Selection . 1869

→ duck: it is a remarkable fact that the young birds, according to Mr. Cunningham, can fly, while the adults have lost this power. 1872

duck. 1859 1860 1861 1866 1869

→ it is probable 1872

I believe 1859 1860 1861 1866 1869

→ by kicking its 1872

from 1859 1860 1861 1866 1869

→ OMIT 1872

of the smaller 1859 1860 1861 1866 1869

→ OMIT 1872

natural selection increased in successive generations 1859 1860 1861 1866 1869

→ were increased during successive generations, its 1872

its 1859 1860 1861 1866 1869

→ not decisive; 1872

very scanty; 1861

not quite decisive; 1866 1869

→ in guinea-pigs, of the inherited effects of operations, 1872

of epilepsy produced by injuring the spinal chord of guinea-pigs, being inherited, 1861 1866

of inherited epilepsy in guinea-pigs, caused by an operation performed on the spinal chord, 1869

the will of

man,

man

→which

accumulating

accumulates

the variations in

cretain

certain

definite

....

→directions; and it is this latter agency which answers to the survival of the fittest under nature.

Effects

→ the increased Use and Disuse of Parts, as controlled by Natural Selection .

From the facts alluded to in the first chapter, I think there can be

little

doubt that use in our domestic animals

strengthens

has strengthened

and

enlarges

enlarged

certain parts, and disuse

diminishes

diminished

them; and that such modifications are inherited. Under free nature, we

can

....

have no standard of comparison, by which to judge of the effects of long-continued use or disuse, for we know not the parent-forms; but many animals

have

possess

structures which can be

explained

ex- plained

best explained

by the effects of disuse. As Professor Owen has remarked, there is no greater anomaly in nature than a bird that cannot fly; yet there are several in this state. The logger-headed duck of South America can only flap along the surface of the water, and has its wings in nearly the same condition as the domestic Aylesbury →duck: it is a remarkable fact that the young birds, according to Mr. Cunningham, can fly, while the adults have lost this power. As the larger ground-feeding birds seldom take flight except to escape danger, →it is probable that the nearly wingless condition of several birds,

which

....

now

inhabit

inhabiting

have

which

lately inhabited several oceanic islands, tenanted by no beast of prey, has been caused by disuse. The ostrich indeed inhabits

continents

continents,

and is exposed to danger from which it cannot escape by flight, but

by kicking

....

it can defend itself →by kicking its enemies, as

well

efficiently

any

many

→OMIT quadrupeds. We may

imagine

believe

that the

early

....

progenitor of the ostrich

had

genus had

habits like those of

the

bustard, and

that

that,

as →OMIT the size and weight of its

body,

body

→were increased during successive generations, its legs were used more, and its wings less, until they became incapable of flight.

Kirby has remarked (and I have observed the same fact) that the anterior tarsi, or feet, of many male dung-feeding beetles are

very

....

often broken off; he examined seventeen specimens in his own collection, and not one had even a relic left. In the Onites apelles the tarsi are so habitually lost, that the insect has been described as not having them. In some other genera they are present, but in a rudimentary condition. In the Ateuchus or sacred

bettle

beetle

of the Egyptians, they are totally deficient. The evidence that accidental mutilations can be inherited is at present →not decisive; but the remarkable

case

cases

observed by Brown-Séquard →in guinea-pigs, of the inherited effects of operations, should make