Origin of Species Variorum

→ should be effected in a species, 1872

should thus in the course of time be produced, it is necessary to believe that when 1861 1866

in any part should be effected, 1869

→ formed must again, perhaps after 1869 1872

arisen, it again varies, after perhaps 1861 1866

→ vary or present individual differences of the same favourable nature as before; and these must be 1872

and that its varieties, if favourable, are 1861 1866

vary or present individual differences of the same favourable nature, and these must be 1869

→ onwards step by step. 1869 1872

onwards. 1861 1866

→ it is true, we can judge only by seeing 1872

all this has actually taken place must be judged by 1869

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

That varieties more or less different from the parent-stock occasionally arise, few will deny; but that the process of variation should be thus indefinitely prolonged is an assumption, the truth of which must be judged of by how far the hypothesis accords with and explains the general phenomena of nature.

→ ordinary belief that the amount of possible variation is a strictly limited quantity is likewise a simple assumption. 1872

general phenomena of nature. 1866

→ OMIT 1869 1872

and the black-grouse that of peaty earth, 1859 1860 1861 1866

→ OMIT 1869 1872

I can see no reason to doubt that 1859 1860 1861 1866

→ in Virginia, determines 1872

determines 1861 1866

in Florida, determines 1869

are

good; silently and insensibly working,

whenever

whenever

and

and

wherever

wherever

opportunity

opportunity

offers,

offers ,

at the improvement of each organic being in relation to its organic and

in organic

inorganic

conditions of life. We see nothing of these slow changes in progress, until the hand of time has marked the

long

....

lapse of ages, and then so imperfect is our view into

long past

long-past

geological ages, that we

only see

see only

that the forms of life are now different from what they formerly were.

In order that any great amount of modification →should be effected in a species, a variety

has

when

once →formed must again, perhaps after a long interval of

time;

time,

→vary or present individual differences of the same favourable nature as before; and these must be again preserved, and so →onwards step by step. Seeing that individual differences of

all

the same

kinds

kind

perpetually recur, this can hardly be considered as an unwarrantable assumption. But whether →it is true, we can judge only by seeing how far the hypothesis accords with and explains the general phenomena of nature. ↑ On the other hand, the →ordinary belief that the amount of possible variation is a strictly limited quantity is likewise a simple assumption.

Although natural selection can act only through and for the good of each being, yet characters and structures, which we are apt to consider as of very trifling importance, may thus be acted on. When we see leaf-eating insects green, and bark-feeders mottled-grey; the alpine ptarmigan white in winter, the red-grouse the colour of heather, →OMIT we must believe that these tints are of service to these birds and insects in preserving them from danger. Grouse, if not destroyed at some period of their lives, would increase in countless numbers; they are known to suffer largely from birds of prey; and hawks are guided by eyesight to their

prey,—

prey—

so much so, that on parts of the Continent persons are warned not to keep white pigeons, as being the most liable to destruction. Hence →OMIT natural selection might be

most

....

effective in giving the proper colour to each kind of grouse, and in keeping that colour, when once acquired, true and constant. Nor ought we to think that the occasional destruction of an animal of any particular colour would produce little effect: we should remember how essential it is in a flock of white sheep to destroy

every

lamb with the faintest trace of black. We have seen how

in Florida

....

the colour of the hogs,

when feeding

which feed

on the

"paint root,"

"paint-root,"

"paint-root"

→in Virginia, determines whether they shall live or die. In

plants

plants,

the down on the fruit and the colour of the flesh are considered by botanists as characters of the most trifling importance: yet we hear from an excellent horticulturist, Downing, that in the United States smooth-skinned fruits suffer far more from a beetle, a

curculio,

Curculio,

than those with down; that purple plums suffer far