Origin of Species Variorum

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

In how important a manner this has acted, has recently been well shown by Sir J. Lubbock in his remarks on the close similarity of the larvæ of some insects belonging to very different orders, and on the dissimilarity of the larvæ of other insects within the same order, according to their habits of life.

→ From such special 1859 1860 1861

From such 1866 1869

Owing to such 1872

→ the 1859 1860 1861 1872

especially when including a division of labour during the different stages of development, as when a larva during one stage has to search for food, and during another stage has to search for a place of attachment, the 1866

especially when they imply a division of labour during the different stages of development, as when the same larva has during one stage to search for food, and has during another stage to search for a place of attachment, the 1869

→ or active embryos 1859 1860 1861

OMIT 1866 1869 1872

→ and cases could be given of the larvæ of two species, or of two groups of species, differing quite as much, or even more, from each other than do their adult parents. 1859 1860 1861

and cases could be given of the larvæ of two species, or of two groups of species, differing much more from each other, than do their adult parents. 1866

and cases could be given of the larvæ of two species, or of two groups of species, differing more from each other than do the adults. 1869

especially when there is a division of labour during the different stages of development, as when the same larva has during one stage to search for food, and during another stage has to search for a place of attachment. 1872

→ as it certainly is, 1859 1860 1861 1866

OMIT 1869 1872

→ to be the case 1859 1860 1861 1866

to be true 1869

OMIT 1872

→ legs, a very 1859 1860 1861 1866 1869

locomotive organs, a 1872

are of

~~any~~

any

use to these

animals.

animals,

~~are~~

are

~~related~~

~~the~~

~~conditions~~

~~which~~

~~they~~

~~are~~

~~exposed.~~

The case, however, is different when an animal during any part of its embryonic career is active, and has to provide for itself. The period of activity may come on earlier or later in life; but whenever it comes on, the adaptation of the larva to its conditions of life is just as perfect and as beautiful as in the adult animal. ↑ →From such special adaptations, →the similarity of the larvæ →or active embryos of allied animals is sometimes

greatly

much

obscured; →and cases could be given of the larvæ of two species, or of two groups of species, differing quite as much, or even more, from each other than do their adult parents. In most cases, however, the

larvæ,

larvæ

though active, still

obey

obey,

more or less

closely

closely,

the law of common embryonic resemblance. Cirripedes afford a good instance of

this;

this:

even the illustrious Cuvier did not perceive that a barnacle

was

was,

→as it certainly is, a crustacean; but a glance at the larva shows this →to be the case in an

unmistakable

unmistakeable

manner. So again the two main divisions of cirripedes, the pedunculated and sessile,

though differing

which differ

widely in external appearance, have larvæ in all their

several

....

stages barely distinguishable.

The embryo in the course of development generally rises in

organisation;

organisation:

I use this expression, though I am aware that it is hardly possible to define clearly what is meant by the organisation being higher or lower. But no one probably will dispute that the butterfly is higher than the caterpillar. In some cases, however, the mature animal

must be

is generally

considered as lower in the scale than the larva, as with certain parasitic crustaceans. To refer once again to cirripedes: the larvæ in the first stage have three pairs of →legs, a very simple single eye, and a probosciformed mouth, with which they feed largely, for they increase much in