Origin of Species Variorum

→ habit and selection have 1872

probably, habit and selection have 1859 1860 1861 1866

habit and selection have probably 1869

→ three,— 1872

three, out of the several which I shall have to discuss in my future work,— 1859 1860 1861 1866

three, out of those which I shall have to discuss in my future work,— 1869

→ Cuckoo — 1872

Cuckoo. — 1866

Cuckoo . — 1869

→ supposed by some naturalists 1869 1872

now commonly admitted 1859 1860 1861 1866

→ instinct of the cuckoo 1869 1872

cuckoo's instinct 1859 1861

cuckoos instinct 1860

most remarkable of the instincts of the cuckoo 1866

→ nest. 1859 1860 1861 1866 1872

nest. If this were the case, the process of laying and hatching might be inconveniently long, more especially as she migrates at a very early period; and the first hatched young would probably have to be fed by the male alone. 1869

→ both asserted and denied 1869 1872

asserted 1859 1860 1861 1866

→ have lately heard from Dr. Merrell, of Iowa, that he once found in Illinois a young cuckoo together with a young jay in the nest of a Blue jay (Garrulus cristatus); and as both were nearly fully feathered, there could be no mistake in their identification. 1872

hear on the high authority of Dr. Brewer, that this is a mistake. 1859 1860 1861 1866

have lately heard from Dr. Merrell, of Iowa, that he once found in Illinois a young cuckoo together with a young jay in the nest of a Blue jay ( Garrulus cristatus ); and as both were nearly fully feathered, there could be no mistake in their identification. 1869

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

Nevertheless, I could give several instances of various birds which have been known occasionally to lay their eggs in other birds' nests.

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

or 1859 1860 1861

→ when reared by 1869 1872

by 1859 1860 1861 1866

→ then 1859 1860 1869 1872

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

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

inherited

inhe- rited

mental changes; in other cases compulsory habit has done nothing, and all has been the result of selection, pursued both methodically and

unconsciously;

unconsciously:

but in most

cases,

cases

→habit and selection have

acted together.

probably concurred.

Special

Instincts.

Instincts .

....

We shall, perhaps, best understand how instincts in a state of nature have become modified by selection, by considering a few cases. I will select only →three,— namely, the instinct which leads the cuckoo to lay her eggs in other

birds

birds'

nests; the slave-making instinct of certain ants; and the

comb-making

cell-making

power of the

hive-bee:

hive-bee;

hive-bee.

these

These

two latter instincts have

generally,

generally

and

most

....

justly,

justly

been ranked by naturalists as the most wonderful of all known instincts.

Instincts

the

→ Cuckoo —

It is →supposed by some naturalists that the more immediate

and final

....

cause of the →instinct of the cuckoo is, that she lays her eggs, not daily, but at intervals of two or three days; so that, if she were to make her own nest and sit on her own eggs, those first laid would have to be left for some time unincubated, or there would be eggs and young birds of different ages in the same →nest. If this were the case, the process of laying and hatching might be inconveniently long, more especially as she

has to

....

migrate

migrates

at a very early period; and the first hatched young would probably have to be fed by the male alone. But the American cuckoo is in this predicament; for she makes her own

nest

nest,

and has eggs and young successively hatched, all at the same time. It has been →both asserted and denied that the American cuckoo occasionally lays her eggs in other

birds

birds'

nests; but I →have lately heard from Dr. Merrell, of Iowa, that he once found in Illinois a young cuckoo together with a young jay in the nest of a Blue jay (Garrulus cristatus); and as both were nearly fully feathered, there could be no mistake in their identification. I could also give several instances of various birds which have been known occasionally to lay their eggs in other birds' nests. ↑ Now let us suppose that the ancient progenitor of our European cuckoo had the habits of the American

cuckoo;

cuckoo,

but

and

that

occasionally she

she occasionally

laid an egg in another

birds

bird

bird's

nest. If the old bird profited by this occasional