Origin of Species Variorum

→ OMIT 1869 1872

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

→ are tempted 1869 1872

might be led 1859 1860 1861 1866

→ this difference as in some necessary manner contingent 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

→ on 1859 1860 1861 1866 1872

necessarily contingent on 1869

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

And in some whole groups of animals and in certain members of other 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 in spiders, "there is nothing worthy to be called a metamorphosis."

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

The larvæ of insects, whether 1859 1860 1861

With almost all insects, the larvæ, whether 1866

→ diversified 1869 1872

the most diverse and active 1859 1860 1861

diversified and active 1866

→ from being placed in the midst of proper nutriment 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

→ or from being fed by their parents; 1869 1872

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

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

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

→ Sometimes 1869 1872

In some cases 1866

→ then through the 1869 1872

through the 1866

→ OMIT 1872

crustaceans would have appeared as nauplii, if there 1866 1869

→ development, all these crustaceans would have appeared as nauplii. 1872

development;— or that they were primordially developed under this form. 1866

development. 1869

be considered as either more highly or more lowly organised than they were in the larval condition. But in some genera the larvæ become developed

either

....

into hermaphrodites having the ordinary structure,

and

into what I have called complemental

males:

males,

males;

and in the

latter,

latter

the development has assuredly been

retrograde;

retrograde,

for the male is a mere sack, which lives for a short

time,

time

and is destitute of mouth, stomach,

and every

other

organs

organ

of importance, excepting

for

those for

reproduction.

We are so much accustomed to see

differences

a difference

in structure between the embryo and the adult, →OMIT that we →are tempted to look at →this difference as in some necessary manner contingent →on growth. But there is no

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

the

their

parts in proper proportion, as soon as any

structure

part

became

visible

the

embryo.

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. ↑ Spiders, again, barely undergo any metamorphosis. →The larvæ of most insects pass through a worm-like stage, whether they are active and adapted to →diversified habits, or

quite

remaining

are

inactive,

inactive

→from being placed in the midst of proper nutriment →or from being fed by their parents; but in some few cases, as in that of Aphis, if we look to the admirable drawings →of the development of this insect, by Professor Huxley, we see

hardly any

trace of the vermiform stage.