Origin of Species Variorum

→ and likewise a close similarity in the embryos of widely different animals within the same class, 1859 1860

and like-wise a close similarity in the embryos of widely different animals within the same class, 1861

and like-wise a close similarity in the embryos of different animals within the same class, 1866

OMIT 1869 1872

→ might be led 1859 1860 1861 1866

are tempted 1869 1872

→ these facts as necessarily contingent in some manner 1859 1860 1861

these facts as in some manner necessarily contingent 1866

this difference as in some manner 1869

this difference as in some necessary manner contingent 1872

→ on 1859 1860 1861 1866 1872

necessarily contingent on 1869

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

In some whole groups of animals and in certain members of other groups this is the case, and the embryo does not at any period differ widely from the adult: thus Owen has remarked in regard to cuttlefish, "there is no metamorphosis; the cephalopodic character is manifested long before the parts of the embryo are completed." Land-shells and fresh-water crustaceans are born having their proper forms, whilst the marine members of the same two great classes pass through considerable and often great changes during their development.

→ the 1859 1860 1861 1866

this is the case, and the 1869

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

Land-shells and fresh-water crustaceans are born with their proper forms, whilst the marine members of these two great classes pass through considerable and often great developmental changes.

→ The larvæ of insects, whether 1859 1860 1861

With almost all insects, the larvæ, whether 1866

The larvæ of most insects pass through a worm-like stage, whether they are active and 1869 1872

→ the most diverse and active 1859 1860 1861

diversified and active 1866

diversified 1869 1872

→ being fed by their parents or placed in the midst of proper nutriment, 1859 1860 1861

being placed in the midst of proper nutriment or fed by their parents, 1866

from being placed in the midst of proper nutriment 1869 1872

→ yet nearly all pass through a similar worm-like stage of development; 1859 1860 1861 1866

or from being fed by their parents; 1869 1872

→ by Professor Huxley of the development of this insect, 1859 1860 1861 1866

of the development of this insect, by Professor Huxley, 1869 1872

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

the general, 1869

the common, 1872

→ each other;— 1859 1860 1861 1866

between the embryos or larvæ 1869 1872

→ structure of 1859 1860 1861 1866

most distinct species in the same class;— 1869 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

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

We are so much accustomed to see

a difference

differences

in structure between the embryo and the adult, →and likewise a close similarity in the embryos of widely different animals within the same class, that we →might be led to look at →these facts as necessarily contingent in some manner →on growth. But there is no

~~obvious~~

obvious

reason why, for instance, the

wings

wing

of a bat, or the

fins

fin

of a porpoise, should not have been sketched out with all

their

the

parts in proper proportion, as soon as any

part

structure

became

visible.

~~the~~

~~embryo.~~

↑

some whole groups of animals and in certain members of other

groups

groups,

→the embryo does not at any period differ widely from the adult: thus Owen has remarked in regard to cuttle-fish, "there is no metamorphosis; the cephalopodic character is manifested long before the parts of the embryo are

completed."

~~and~~

~~again~~

~~spiders,~~

~~"there~~

~~nothing~~

~~worthy~~

~~called~~

~~metamorphosis."~~

↑ →The larvæ of insects, whether adapted to →the most diverse and active habits, or

remaining

are

quite

inactive

inactive,

→being fed by their parents or placed in the midst of proper nutriment, →yet nearly all pass through a similar worm-like stage of development; but in some few cases, as in that of Aphis, if we look to the admirable drawings →by Professor Huxley of the development of this insect, we see

hardly any

trace of the vermiform stage.

How, then, can we explain these several facts in embryology,—

namely,

namely

the very general,

though

but

not

universal,

universal

difference in structure between the embryo and the adult;—

the various

parts in the same

individual

indivividual

embryo

embryo,

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

this

early period of growth alike;— →of embryos of different species within the same class, generally, but not

invariable,

universally,

resemblance

resembling

→each other;— of the →structure of the embryo →not being closely related to its conditions of existence, except when the embryo becomes at any period of life active and has