Origin of Species Variorum

→ must by no means overlook the effects of the definite action of changed conditions of life,— of so-called spontaneous variations, which seem to depend in a quite subordinate degree 1872

should remember that climate, food, &c., probably have some little direct influence 1859 1860 1861 1866

should remember that climate, food, &c., probably have had some, perhaps a considerable, direct influence 1869

→ nature of the conditions,— of the tendency to reversion to long-lost characters,— of the complex 1872

organisation; that characters reappear from the 1859 1860 1861 1866 1869

→ growth, such as of correlation, compensation, of the pressure of one part on another, &c.,— 1872

reversion; that correlation of growth will have had a most important influence in modifying various structures; 1859 1860 1861 1866

reversion; that correlation is an important element of change; 1869

→ by which 1872

will often have largely modified the external 1859 1860 1861 1866

has often largely modified the external 1869

→ use to one sex are often gained and then transmitted more or less perfectly to the other sex, though of no use to this sex. 1872

animals having a will, to give one male an advantage in fighting with another or in charming the females. 1859 1860 1861 1866

the higher animals, so as to give one male an advantage in fighting with other males, or in charming the female; and characters gained through sexual selection may be transmitted to both sexes. 1869

→ But structures thus indirectly gained, although 1872

Moreover when a modification of structure has primarily arisen from the above or other unknown causes, it may 1859 1860 1861

Moreover, when a modification of structure has primarily arisen from the above or other unknown causes, it may 1866

Moreover a modification, caused in any of the above specified ways, may 1869

→ advantage to a 1872

advantage to the 1859 1860 1861 1866

direct advantage to a 1869

→ its modified descendants, 1872

the descendants of the species 1859 1860 1861 1866

its descendants 1869

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

To give a few instances to illustrate these latter remarks.

→ If 1859 1860 1861 1866 1872

If, for instance, 1869

→ OMIT 1869 1872

I have no doubt that 1859 1860

we cannot doubt that 1861 1866

→ probably in chief part due 1869 1872

due to some quite distinct cause, probably 1859 1860 1861 1866

→ and which, as there is reason to believe from the distribution of the thorn-bearing species in Africa and South America, serve as a defence against browsing quadrupeds, so the spikes 1872

the hooks 1859 1860 1861 1866

and which there is reason to believe from the distribution of the thorn-bearing species in Africa and South America, serves as a defence against browsing quad- rupeds, so the hooks 1869

→ at first 1872

have arisen from unknown laws of growth, and 1859 1860 1861 1866

first 1869

→ developed for this object, and subsequently have been improved and 1872

subsequently 1859 1860 1861 1866

developed for this object, and subsequently been 1869

→ as it underwent 1869 1872

undergoing 1859 1860 1861 1866

→ of each slight variation or individual difference; 1869 1872

producing slight and unimportant variations; 1859 1860 1861 1866

We →must by no means overlook the effects of the definite action of changed conditions of life,— of so-called spontaneous variations, which seem to depend in a quite subordinate degree on the →nature of the conditions,— of the tendency to reversion to long-lost characters,— of the complex

law

laws

of →growth, such as of correlation, compensation, of the pressure of one part on another, &c.,— and

finally,

finally

that

sexual

selection

selection,

→by which characters of →use to one sex are often gained and then transmitted more or less perfectly to the other sex, though of no use to this sex. →But structures thus indirectly gained, although at first

have been

....

of no →advantage to a species,

but

....

may subsequently have been taken advantage of by →its modified descendants, under new conditions of life and

with

....

newly acquired habits. ↑

→If green woodpeckers alone had existed, and we did not know that there were many black and pied kinds, I dare say that we should have thought that the green colour was a beautiful adaptation to

hide

conceal

this tree-frequenting bird from its enemies; and consequently that it was a character of

importance

importance,

and

might have

had

been acquired through natural selection; as it is, →OMIT the colour is →probably in chief part due to sexual selection. A trailing

bamboo

palm

in the Malay

Archipelego

Archipelago

climbs the loftiest trees by the aid of exquisitely constructed hooks clustered around the ends of the branches, and this contrivance, no doubt, is of the highest service to the plant; but as we see nearly similar hooks on many trees which are not climbers, →and which, as there is reason to believe from the distribution of the thorn-bearing species in Africa and South America, serve as a defence against browsing quadrupeds, so the spikes on the

bamboo

palm

may →at first have been →developed for this object, and subsequently have been improved and taken advantage of by the

plant

plant,

→as it underwent further modification and

becoming

became

a climber. The naked skin on the head of a vulture is generally

looked at

considered

as a direct adaptation for wallowing in putridity; and so it may be, or it may possibly be due to the direct action of putrid matter; but we should be very cautious in drawing any such inference, when we see that the skin on the head of the clean-feeding male

turkey

Turkey

is likewise naked. The sutures in the skulls of young mammals have been advanced as a beautiful adaptation for aiding parturition, and no doubt they facilitate, or may be indispensable for this act; but as sutures occur in the skulls of young birds and reptiles, which have only to escape from a broken egg, we may infer that this structure has arisen from the laws of growth, and has been taken advantage of in the parturition of the higher animals.

We are profoundly ignorant of the

causes

cause

→of each slight variation or individual difference;