Origin of Species Variorum

→ or 1859 1860 1861

through being enabled to migrate earlier or through any other cause; or 1866 1869 1872

→ by 1859 1860 1861 1866

when reared by 1869 1872

→ and by having to migrate at a very early period; then 1861

then 1859 1860 1869 1872

and by having to migrate at an early period; then 1866

→ could be, and 1859 1860 1861 1866

OMIT 1869 1872

→ I may add that, according to Dr. Gray and to some other observers, the European cuckoo has not utterly lost all maternal love and care for her own offspring. 1859 1860 1861

I may add that, according to Dr. Gray and some other observers, the European cuckoo has not utterly lost all maternal love and care for her own offspring. 1866

It has, also, recently been ascertained that the cuckoo occasionally lays her eggs on the bare ground, sits on them and feeds her young; this rare and strange event evidently is a case of reversion to the long-lost aboriginal instinct of nidification. 1869

↑ 2 blocks not present in 1859 1860 1861 1866 1869; present in 1872

It has, also, recently been ascertained on sufficient evidence, by Adolf Müller, that the cuckoo occasionally lays her eggs on the bare ground, sits on them, and feeds her young. This rare event is probably a case of reversion to the long-lost, aboriginal instinct of nidification.

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

It has been objected by some authors that I have not noticed other related instincts and points of structure in the cuckoo, which are falsely spoken of as necessarily co-ordinated.

→ The occasional habit of birds laying 1859 1860 1861 1866 1869

Various birds, as has already been remarked, occasionally lay 1872

→ other birds' nests, either of the same or of a distinct species, 1859 1861

other birds nests, either of the same or of a distinct species, 1860

other birds' nests, either of the same or of distinct species, 1866

other birds nests, either of the same or of distinct species, 1869

the nests of other birds. This habit 1872

→ this perhaps explains the origin of a 1859 1860 1861 1866 1869

throws some light on the 1872

→ allied group of 1859 1860 1861 1866

nearest allied group, that of 1869

OMIT 1872

→ For several hen ostriches, at least in the case of the American species, 1859 1860 1861

For several hen ostriches 1866 1869

In this family several hen-birds 1872

~~Nevertheless,~~

Nevertheless,

I could

also give

give

several instances of various birds which have been known occasionally to lay their eggs in other

birds

bird's

birds'

nests. Now let us suppose that the ancient progenitor of our European cuckoo had the habits of the American

cuckoo,

cuckoo;

and

but

that

she occasionally

occasionally she

laid an egg in another

birds

bird

bird's

nest. If the old bird profited by this occasional

habit

habit,

→or if the young were made more vigorous by advantage

being

having been

taken of the mistaken

~~maternal~~

maternal

instinct of another

species,

species

bird,

than →by their own

mothers

mother,

mother's

~~care,~~

care,

encumbered as she

could

can

hardly fail to be by having eggs and young of different ages at the same

time;

time,

→and by having to migrate at a very early period; then the old birds or the fostered young would gain an advantage. And analogy would lead

to believe, that the young thus reared would be apt to follow by inheritance the occasional and aberrant habit of their mother, and in their turn would be apt to lay their eggs in other

birds

birds'

nests, and thus be

more successful

successful

in rearing their young. By a continued process of this nature, I believe that the strange instinct of our cuckoo →could be, and has

been

been,

generated. →I may add that, according to Dr. Gray and to some other observers, the European cuckoo has not utterly lost all maternal love and care for her own offspring. ↑ ↑

→The occasional habit of birds laying their eggs in →other birds' nests, either of the same or of a distinct species, is not very uncommon with the

Gallinaceæ

Gallinaceæ,

Gallinaceæ;

and →this perhaps explains the origin of a singular instinct

the →allied group of

ostrich.

ostriches.

→For several hen ostriches, at least in the case of the American species, unite and lay first a few eggs in one nest and then in another; and these are hatched by the males. This instinct may probably be accounted for by the fact