Origin of Species Variorum

→ disputed, — then 1869

disputed,— 1866 1872

↑ 13 blocks not present in 1859 1860 1861 1866 1869; present in 1872

Some species of Molothrus, a widely distinct genus of American birds, allied to our starlings, have parasitic habits like those of the cuckoo; and the species present an interesting gradation in the perfection of their instincts. The sexes of Molothrus badius are stated by an excellent observer, Mr. Hudson, sometimes to live promiscuously together in flocks, and sometimes to pair. They either build a nest of their own, or seize on one belonging to some other bird, occasionally throwing out the nestlings of the stranger. They either lay their eggs in the nest thus appropriated, or oddly enough build one for themselves on the top of it. They usually sit on their own eggs and rear their own young; but Mr. Hudson says it is probable that they are occasionally parasitic, for he has seen the young of this species following old birds of a distinct kind and clamouring to be fed by them. The parasitic habits of another species of Molothrus, the M. bonariensis, are much more highly developed than those of the last, but are still far from perfect. This bird, as far as it is known, invariably lays its eggs in the nests of strangers; but it is remarkable that several together sometimes commence to build an irregular untidy nest of their own, placed in singularly ill-adapted situations, as on the leaves of a large thistle. They never, however, as far as Mr. Hudson has ascertained, complete a nest for themselves. They often lay so many eggs— from fifteen to twenty— in the same foster-nest, that few or none can possibly be hatched. They have, moreover, the extraordinary habit of pecking holes in the eggs, whether of their own species or of their foster-parents, which they find in the appropriated nests. They drop also many eggs on the bare ground, which are thus wasted. A third species, the M. pecoris of North America, has acquired instincts as perfect as those of the cuckoo, for it never lays more than one egg in a foster-nest, so that the young bird is securely reared. Mr. Hudson is a strong disbeliever in evolution, but he appears to have been so much struck by the imperfect instincts of the Molothrus bonariensis that he quotes my words, and asks, "Must we consider these habits, not as especially endowed or created instincts, but as small consequences of one general law, namely, transition? "

→ 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 distinct species, 1869

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

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

→ nearest allied group, that of 1869

allied group of 1859 1860 1861 1866

OMIT 1872

→ For several hen ostriches 1866 1869

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

In this family several hen-birds 1872

→ case of the 1859 1860 1861 1866 1869

OMIT 1872

→ has 1859 1860 1861 1866 1869

as in the case of the Molothrus bonariensis, has 1872

→ kinds of bees. 1869 1872

kinds. 1859 1860 1861 1866

→ have been indispensable 1869 1872

be necessary 1859 1860 1861 1866

→ likewise, of Sphegidæ (wasp-like insects) are 1859 1860 1861 1866 1869

of Sphegidæ (wasp-like insects) are likewise 1872

→ in the same manner on other species; 1869

on other species; 1859 1860 1861 1866

OMIT 1872

→ OMIT 1869 1872

to feed on, 1859 1860 1861 1866

be →disputed, — then

then

the

the instincts

instincts

and structure of the young

can

could

be slowly modified as

surely

well

as those of the

adult,

adult;

and both cases must stand or fall

together

....

with the whole theory of natural selection. ↑

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

Gallinaceæ

Gallinaceæ,

Gallinaceæ;

and →this perhaps explains the origin of a singular instinct

the →nearest allied group, that of

ostrich.

ostriches.

→For several hen ostriches 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 of the

here

hens

laying a large number of

eggs;

eggs,

but, as

with

the →case of the cuckoo, at intervals of two or three days.

This

The

instinct, however, of the American

ostrich,

ostrich

→has not as yet been perfected; for a surprising number of eggs lie strewed over the plains, so that in one

day's

days

hunting I picked up no less than twenty lost and wasted eggs.

Many bees are parasitic, and

always

regularly

lay their eggs in the nests of

bees of

....

other →kinds of bees. This case is more remarkable than that of the cuckoo; for these bees have not only

their

had their

instincts but their structure modified in accordance with their parasitic habits; for they do not possess the pollen-collecting apparatus which would →have been indispensable if they had

....

store

stored

up food

food

for their own young. Some

species

species,

→likewise, of Sphegidæ (wasp-like insects) are

parasitic;

parasitic

→in the same manner on other species; and M. Fabre has lately shown good reason for believing

that

that,

although the Tachytes nigra generally makes its own burrow and stores it with paralysed prey for its own

larvæ

larvæ,

→OMIT yet

that

that,

when this insect finds a burrow already made and stored by another sphex, it takes advantage of the prize, and becomes for the occasion parasitic. In this case, as with