Origin of Species Variorum

→ Owing to such 1872

From such special 1859 1860 1861

From such 1866 1869

→ 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

→ OMIT 1866 1869 1872

or active embryos 1859 1860 1861

→ 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

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

→ OMIT 1869 1872

as it certainly is, 1859 1860 1861 1866

→ OMIT 1872

to be the case 1859 1860 1861 1866

to be true 1869

→ locomotive organs, a 1872

legs, a very 1859 1860 1861 1866 1869

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. 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

widely

very

different orders, and on the dissimilarity of the larvæ of other insects

belonging to

within

the same order, according to their habits of life. →Owing to such adaptations, →the similarity of the larvæ →OMIT of allied animals is sometimes

much

greatly

obscured; →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. Cases can even be given of the larvæ of allied species, or groups of species, differing more from each other than do the adults. 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

→OMIT a crustacean; but a glance at the larva shows this →OMIT in an

unmistakeable

unmistakable

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

which differ

though differing

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

is generally

must be

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 →locomotive organs, a simple single eye, and a probosciformed mouth, with which they feed largely, for they increase much in size. In the second stage, answering to the chrysalis stage of butterflies, they have six pairs of beautifully constructed natatory legs, a pair of magnificent compound eyes, and extremely complex

antennæ

antennæ;

but they have a closed and imperfect

mouth;

mouth,

and cannot feed: their function at this stage is, to search

out by

their well-developed organs of sense, and to reach by their active powers of swimming, a proper place on which to become attached and to undergo their final metamorphosis. When this is completed they are fixed for life: their legs are now converted into prehensile organs; they again obtain a well-constructed mouth; but they have no antennæ, and their two eyes are now reconverted into a minute, single,

and very

....

simple eye-spot. In this last and complete state, cirripedes may