Origin of Species Variorum

↑ 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.

→ It may be worth while to give another and 1869

Let us now take a 1859 1860 1861 1866

→ illustration of the action of natural selection. 1869

case. 1859 1860 1861 1866

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

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

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

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

as can be fully proved, gives rise to 1872

migratory birds, which almost always return to the same

spot.

district.

Consequently each newly-formed variety would generally be at first local, as seems to be the common rule with varieties in a state of nature; so that similarly modified individuals would soon exist in a small body together, and would often breed together. If the new variety

were

was

successful in its battle for life, it would slowly spread from a central

district,

spot,

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

→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,

the

their

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~~

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 we have good rea- son to believe, would produce