Origin of Species Variorum

→ the common, 1872

of embryos of different species within the same class, generally, 1859 1860 1861 1866

the general, 1869

→ between the embryos or larvæ 1869 1872

each other;— 1859 1860 1861 1866

→ most distinct species in the same class;— 1869 1872

structure of 1859 1860 1861 1866

→ often retaining whilst within the egg or womb, structures which are of no service to it, either at that or at a later period of life; on the other hand larvæ, which have 1872

not being closely related to its conditions of existence, except when the embryo becomes at any period of life active and has 1859 1860 1861

not being closely related to its conditions of existence, existence, except when the embryo becomes at any period of life active and has 1866

retaining whilst within the egg or womb, structures which are of no service to it, either at that period or later in life; whilst embryos at a later period, or larvæ, which have 1869

→ their own wants, being perfectly adapted to the surrounding conditions;— and lastly the fact of certain larvæ standing higher in the scale of 1872

itself;— of the embryo apparently having sometimes a higher 1859 1860 1861 1866

their own wants, are perfectly adapted to the surrounding conditions;— and lastly the fact of certain larvæ standing higher in the scale of 1869

→ or individual differences necessarily 1869 1872

necessarily 1859 1860 1861 1866

→ head, but what we have certainly 1869 1872

head— indeed the evidence rather 1859 1860 1861 1866

→ birth, what will be the 1872

the animal has been born, what its 1859 1860 1861 1866

birth, what the 1869

→ demerits of their young animals. 1872

form will ultimately turn out. 1859 1860 1861 1866

form of their young animals will turn out. 1869

→ the effects are 1869 1872

it is fully 1859 1860 1861 1866

→ on one or both parents before the act of generation. 1872

even before the embryo is formed; and the variation may be due to the male and female sexual elements having been affected by the conditions to which either parent, or their ancestors, have been exposed. 1859 1860 1861 1866

on one or both parents before reproduction. 1869

↑ 2 blocks not present in 1869 1872; present in 1859 1860 1861 1866

Nevertheless an effect thus caused at a very early period, even before the formation of the embryo, may appear late in life; as when an hereditary disease, which appears in old age alone, has been communicated to the offspring from the reproductive element of one parent. Or again, as when the horns of cross-bred cattle have been affected by the shape of the horns of either parent.

→ It deserves notice that it is of no importance to 1869 1872

For the welfare of 1859 1860 1861 1866

→ OMIT 1869 1872

be quite unimportant whether most 1859 1860 1861 1866

→ whilst young it possessed 1869 1872

it assumed 1859 1860 1861 1866

↑ 2 blocks not present in 1869 1872; present in 1859 1860 1861 1866

Hence, I conclude, that it is quite possible, that each of the many successive modifications, by which each species has acquired its present structure, may have supervened at a not very early period of life; and some direct evidence from our domestic animals supports this view. But in other cases it is quite possible that each successive modification, or most of them, may have appeared at an extremely early period.

→ OMIT 1869 1872

there is some evidence to render it probable, that 1859 1860 1861

there is a large body of facts rendering it probable, that 1866

→ full-grown horns of 1869 1872

horns of almost full-grown 1859 1860 1861 1866

→ cattle. 1859 1860 1866 1869 1872

cattle. But further than this, variations which, for all that we can see, might have appeared earlier or later in life, tend to appear at a corresponding age in the offspring and parent. 1861

→ But 1869 1872

But further than this, 1859 1860 1866

I am far from meaning that this 1861

→ variations, which, for all that we can see might have first appeared either earlier or later in life, likewise tend to re-appear at a corresponding age 1872

variations which, for all that we can see, might have appeared earlier or later in life, tend to appear at a corresponding age 1859 1860 1866

is invariably the case; and I could give a good many cases of variations (taking the word 1861

variations, which, for all that we can see might have appeared either earlier or later in life, likewise tend to appear at a corresponding age 1869

→ offspring and 1859 1860 1866 1869 1872

largest sense) which have supervened at an earlier age in the child than in the 1861

→ several exceptional 1869 1872

a good many 1859 1860 1866

indivividual

individual

embryo

embryo,

which ultimately become very unlike and serve for diverse purposes, being at

this

early period of growth alike;— →the common, but not

universally,

invariable,

resembling

resemblance

→between the embryos or larvæ of the →most distinct species in the same class;— the embryo →often retaining whilst within the egg or womb, structures which are of no service to it, either at that or at a later period of life; on the other hand larvæ, which have to provide for →their own wants, being perfectly adapted to the surrounding conditions;— and lastly the fact of certain larvæ standing higher in the scale of organisation than the mature

animal,

animals

animal

into which

it is

they are

developed.

developed?

I believe that all these facts can be

ex- plained,

follows,

the

view

descent

with

modification.

It is commonly assumed, perhaps from monstrosities

often

....

affecting the

embryos

embryo

at a very early period, that slight variations →or individual differences necessarily appear at an equally early period.

But we

have little evidence on this →head, but what we have certainly points the other way; for it is notorious that breeders of cattle, horses, and various fancy animals, cannot positively tell, until some time after →birth, what will be the merits or →demerits of their young animals. We see this plainly in our own children; we cannot

always

....

tell whether

the

child will be tall or short, or what its precise features will be. The question is not, at what period of life

any

each

variation

has

may have

been caused, but at what period →the effects are displayed. The cause may have acted, and I believe

generally

often

has acted, →on one or both parents before the act of generation. ↑ →It deserves notice that it is of no importance to a very young animal, as long as it remains in its

mothers

mother's

womb,

womb

or in the egg, or as long as it is nourished and protected by its parent,

whether

must

most

→OMIT of its characters are

fully

....

acquired a little earlier or later in life. It would not signify, for instance, to a bird which obtained its food

best

....

by having a

long

much-curved

beak,

beak

whether or not →whilst young it possessed a beak of this

particular length,

shape,

as long as it was fed by its parents. ↑

I have stated in the first chapter, that →OMIT at whatever age

any

variation first appears in the parent, it tends to

reappear

re-appear

at a corresponding age in the offspring. Certain variations can only appear at corresponding

ages,

ages;

for instance, peculiarities in the caterpillar, cocoon, or imago states of the

silk-moth;

silk-moth:

or, again, in the →full-grown horns of →cattle. →But →variations, which, for all that we can see might have first appeared either earlier or later in life, likewise tend to re-appear at a corresponding age in the →offspring and parent. I am far from meaning that this is invariably the

case;

case,

and I could give →several exceptional cases of variations (taking the word in the largest sense) which have supervened at an earlier age in the child than in the