Origin of Species Variorum

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

But to the subject of intercrossing we shall have to return. It may be objected by those who have not attended to natural history, that the long-continued accumulation of individual differences could not give rise to parts or organs which seem to us, and are often called, new. But, as we shall hereafter find, it is difficult to advance any good instance of a really new organ; even so complex and perfect an organ as the eye can be shown to graduate downwards into mere tissue sensitive to diffused light.

↑ 8 blocks not present in 1869 1872; present in 1859 1860 1861 1866

Even without any change in the proportional numbers of the animals on which our wolf preyed, a cub might be born with an innate tendency to pursue certain kinds of prey. Nor can this be thought very improbable; for we often observe great differences in the natural tendencies of our domestic animals; one cat, for instance, taking to catch rats, another mice; one cat, according to Mr. St. John, bringing home winged game, another hares or rabbits, and another hunting on marshy ground and almost nightly catching woodcocks or snipes. The tendency to catch rats rather than mice is known to be inherited. Now, if any slight innate change of habit or of structure benefited an individual wolf, it would have the best chance of surviving and of leaving offspring. Some of its young would probably inherit the same habits or structure, and by the repetition of this process, a new variety might be formed which would either supplant or coexist with the parent-form of wolf. Or, again, the wolves inhabiting a mountainous district, and those frequenting the lowlands, would naturally be forced to hunt different prey; and from the continued preservation of the individuals best fitted for the two sites, two varieties might slowly be formed. These varieties would cross and blend where they met; but to this subject of intercrossing we shall soon have to return. I may add, that, according to Mr. Pierce, there are two varieties of the wolf inhabiting the Catskill Mountains in the United States, one with a light greyhound-like form, which pursues deer, and the other more bulky, with shorter legs, which more frequently attacks the shepherd's flocks.

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

Let us now take a more complex case.

→ for instance, by 1869 1872

by 1859 1860 1861 1866

→ insects; but their visits do not in any way benefit the plant. 1869 1872

insects. 1859 1860 1861 1866

→ Now, let us suppose that the 1869 1872

Let us now suppose a little sweet 1859 1860 1861 1866

→ was excreted from the inside 1869 1872

to be excreted by the inner bases 1859 1860 1861 1866

→ certain number of plants of any species. 1869 1872

flower. 1859 1860 1861 1866

→ OMIT 1869 1872

In this case 1859 1860 1861 1866

→ another. 1869 1872

the stigma of another flower. 1859 1860 1861 1866

→ as can be fully proved, gives rise to 1872

we have good reason to believe (as will hereafter be more fully alluded to), would produce very 1859 1860 1861 1866

as we have good rea- son to believe, would produce 1869

→ OMIT 1869 1872

from flower to flower, 1859 1860 1861 1866

→ to be a 1869 1872

a 1859 1860 1861 1866

→ to be thus robbed; and the 1872

and those 1859 1860 1861 1866

and the 1869

→ the above process long continued, 1869 1872

this process of the continued preservation or natural selection of more and more attractive flowers, 1859 1860 1861 1866

→ OMIT 1869 1872

can most effectually 1859 1860 1861

can effectually 1866

→ one, 1869 1872

one— not as a very striking case, but 1859 1860 1861 1866

spot,

district,

competing with and conquering the unchanged individuals on the margins of an ever-increasing circle. ↑ ↑ ↑

It may be worth while to give another and more complex illustration of the action of natural selection. Certain plants excrete

....

sweet juice, apparently for the sake of

elimi- nating

eliminating

something injurious

from,

from

their

the

sap: this is

effected

effected,

→for instance, by glands at the base of the stipules in some Leguminosæ, and at the

back

backs

of the

leaf

leaves

of the common laurel. This juice, though small in quantity, is greedily sought by →insects; but their visits do not in any way benefit the plant. →Now, let us suppose that the juice or nectar →was excreted from the inside of the

petals

flowers

of a →certain number of plants of any species. →OMIT

insects

Insects

in seeking the nectar would get dusted with pollen, and would

certainly

....

often transport

the pollen

from one flower to →another. The flowers of two distinct individuals of the same species would thus get crossed; and the act of crossing, →as can be fully proved, gives rise to vigorous seedlings, which consequently would have the best chance of flourishing and surviving. The plants which produced flowers with the largest glands or nectaries, excreting most nectar, would oftenest be visited by insects, and would oftenest be crossed; and so in the long-run would gain the upper hand and form a local variety.

Those

The

flowers, also, which had their stamens and pistils placed, in relation to the size and habits of the particular

insects

insects,

insect

which visited them, so as to favour in any degree the transportal of

their

the

pollen

pollen,

→OMIT would likewise be

favoured

favoured.

....

selected.

....

We might have taken the case of insects visiting flowers for the sake of collecting pollen instead of nectar; and as pollen is formed for the sole

object

purpose

of fertilisation, its destruction appears →to be a simple loss to the plant; yet if a little pollen were carried, at first occasionally and then habitually, by the pollen-devouring insects from flower to flower, and a cross thus effected, although nine-tenths of the pollen were destroyed, it might still be a great gain to the

plant;

plant

→to be thus robbed; and the individuals which produced more and more pollen, and had larger

and larger

....

anthers, would be selected.

When our plant, by →the above process long continued, had been rendered highly attractive to insects, they would, unintentionally on their part, regularly carry pollen from flower to flower; and that they →OMIT do

this,

this