Origin of Species Variorum

→ not to lay much 1869

to lay very little 1859 1860 1861 1866

to lay less 1872

→ and definite action 1869

action 1859 1860 1861 1866 1872

→ conditions of life; but I fully admit that strong arguments of a general nature may be advanced on the other side. 1869

conditions of life. 1859 1860 1861 1866

surrounding conditions, than on a tendency to vary, due to causes of which we are quite ignorant. 1872

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

Indirectly, as already remarked, they seem to play an important part in affecting the reproductive system, and in thus inducing variability; and natural selection will then accumulate all profitable variations, however slight, until they become plainly developed and appreciable by us.

→ one sense 1869 1872

a far-fetched sense, however, 1866

→ but 1866 1869

either directly or indirectly, but 1872

→ OMIT 1869 1872

it depends on the nature of 1866

→ when man is the selecting agent, we clearly see that the 1869 1872

we see in selection by man, that these 1866

→ the conditions cause the variability; 1869

the conditions under domestication causing the variability, and 1866

variability is in some manner excited, but it is 1872

→ acting either consciously or unconsciously, 1866 1869

which 1872

→ directions, and this answers to the survival of the fittest under nature. 1869

directions. 1866

directions; and it is this latter agency which answers to the survival of the fittest under nature. 1872

→ Use and Disuse, as controlled by Natural Selection . 1869

Use and Disuse .— 1859 1860 1861

Use and Disuse, as controlled by Natural Selection. 1866

the increased Use and Disuse of Parts, as controlled by Natural Selection . 1872

→ duck. 1859 1860 1861 1866 1869

duck: it is a remarkable fact that the young birds, according to Mr. Cunningham, can fly, while the adults have lost this power. 1872

→ I believe 1859 1860 1861 1866 1869

it is probable 1872

every

naturalist

naturalist,

of species keeping true, or not varying at all, although living under the most opposite climates. Such considerations as these incline me →not to lay much weight on the direct →and definite action of the →conditions of life; but I fully admit that strong arguments of a general nature may be advanced on the other side. ↑

In →one sense the conditions of life may be said, not only to cause variability, →but likewise to include natural

selection,

selection;

for →OMIT the conditions

whether

determine whether

this or that variety shall

be preserved.

survive.

But →when man is the selecting agent, we clearly see that the two elements of change are

essenitally

....

distinct; →the conditions cause the variability; the will of

man

man,

→acting either consciously or unconsciously,

accumulating

accumulates

the variations in

cretain

certain

definite

....

→directions, and this answers to the survival of the fittest under nature.

Effects

→ Use and Disuse, as controlled by Natural Selection .

From the facts alluded to in the first chapter, I think there can be

little

doubt that use in our domestic animals

has strengthened

strengthens

and

enlarged

enlarges

certain parts, and disuse

diminished

diminishes

them; and that such modifications are inherited. Under free nature, we

can

....

have no standard of comparison, by which to judge of the effects of long-continued use or disuse, for we know not the parent-forms; but many animals

possess

have

structures which can be

ex- plained

best explained

explained

by the effects of disuse. As Professor Owen has remarked, there is no greater anomaly in nature than a bird that cannot fly; yet there are several in this state. The logger-headed duck of South America can only flap along the surface of the water, and has its wings in nearly the same condition as the domestic Aylesbury →duck. As the larger ground-feeding birds seldom take flight except to escape danger, →I believe that the nearly wingless condition of several birds,

~~which~~

which

now

inhabiting

inhabit