Origin of Species Variorum

→ in any part should be effected, 1869

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

should be effected in a species, 1872

→ 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, and these must be 1869

and that its varieties, if favourable, are 1861 1866

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

→ onwards step by step. 1869 1872

onwards. 1861 1866

→ all this has actually taken place must be judged by 1869

it is true, we can judge only by seeing 1872

↑ 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.

→ 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

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 →in any part should be effected, 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, and these must be again preserved, and so →onwards step by step. Seeing that individual differences of

the same

all

kind

kinds

perpetually recur, this can hardly be considered as an unwarrantable assumption. But whether →all this has actually taken place must be judged by 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~~

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