Origin of Species Variorum

→ OMIT 1869 1872

during a course of modification carried on for many generations, 1859 1860 1861 1866

→ at a very early age for their own wants, and 1869 1872

for their own wants at a very early stage of development, and secondly, 1859 1860 1861

at a very early stage of development for their own wants, and secondly, 1866

→ OMIT 1869 1872

exactly 1859 1860 1861

(and this might often be of advantage to a species) exactly 1866

→ OMIT 1869 1872

species, that the child 1859 1860 1861 1866

→ OMIT 1869 1872

at a very early age 1859 1860 1861 1866

→ as their parents. 1869 1872

with its parents, in accordance with their similar habits. 1859 1860 1861 1866

→ the process of slowly modifying and adapting 1872

if 1866

→ to live on the land or in fresh water, instead of 1872

during a long succession of generations had to change its habits from living 1866

→ OMIT 1872

to living on the land or in fresh-water, it 1866

→ simplified by its not passing through any larval stage; 1872

advantage to its descendants during their modification if they were to lose their metamorphoses; 1866

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

Therefore the modification of a marine animal into a terrestrial or fresh-water one would generally be much more easily effected, if its metamorphoses were suppressed through the gradual acquirement at an earlier and earlier age of the adult structure.

→ In this case the gradual acquirement at an earlier and earlier age 1872

Again, with respect to the singular fact of so many terrestrial and fresh-water animals not undergoing any metamorphosis, whilst marine members 1869

→ adult structure 1872

same groups pass through various transformations, Fritz Müller has suggested that the process of slowly modifying and adapting an animal to live on the land or in fresh water, instead of in the sea, 1869

→ favoured by natural selection; and all traces of former metamorphoses would finally be lost. 1872

greatly simplified by its not passing through any larval stage; for it is not probable that places well adapted for both the larval and mature stages, under such new and greatly changed habits of life, could be found unoccupied or ill-occupied by other organisms. 1869

→ of an animal to 1869 1872

to 1859 1860 1861

→ slightly 1869 1872

in any degree 1859 1860 1861

→ plan, or if it profited a larva already different from its parent to change still further, 1872

manner, 1859 1860 1861 1869

→ then, 1859 1860 1861 1872

or if it profited a larva already widely different from its parent to change still further, then, 1869

→ the larvæ might 1869 1872

larvæ might easily 1859 1860

larvæ might 1861

→ more and more different 1869 1872

different to any conceivable extent 1859 1860 1861

→ parents to any conceivable extent. 1869 1872

parents. 1859 1860 1861

→ in the larva might, 1872

might, 1859 1860 1861

in the larvæ might, 1869

→ come to differ 1869 1872

differ 1859 1860 1861

→ is 1869 1872

we have seen to be 1859 1860 1861

→ OMIT 1869 1872

said to be 1859 1860 1861

→ animals might come to pass through stages of development, perfectly distinct from the primordial condition of their adult progenitors. 1872

the metamorphoses of certain animals might first have been acquired, and subsequently transmitted to numerous modified descendants. 1866

animals in certain cases might come to pass through stages of development, perfectly distinct from their primordial, adult condition. 1869

we can see that this would

result

from the

two

....

following

contingencies:

contin- gencies:

contingencies;

firstly,

namely,

from the

young,

young

→OMIT having to provide →at a very early age for their own wants, and from their following →OMIT the same habits of life with their parents; for in this case, it would be indispensable for

the

their

existence

that

the

they

→OMIT should be modified →OMIT in the same manner →as their parents. Again, with respect to the singular fact

of so

that

many terrestrial and fresh-water animals

not

do not

undergoing

undergo

any metamorphosis, whilst

the

....

marine members of the same

classes

groups

pass through various transformations, Fritz

Müller

has suggested that →the process of slowly modifying and adapting an animal →to live on the land or in fresh water, instead of in the

sea

sea,

→OMIT would be

....

great

greatly

→simplified by its not passing through any larval stage; for it is not probable that places well adapted for both the larval and mature stages, under such new and greatly changed habits of life,

could

would

commonly be

found unoccupied or ill-occupied by other organisms. ↑ →In this case the gradual acquirement at an earlier and earlier age of the →adult structure would be → favoured by natural selection; and all traces of former metamorphoses would finally be lost. If, on the other hand, it profited the young →of an animal to follow habits of life →slightly different from those of

their parent,

the parent-form,

and consequently to be constructed

a slightly different →plan, or if it profited a larva already different from its parent to change still further, →then, on the principle of inheritance at corresponding ages, the

active

....

young or →the larvæ might be rendered by natural selection →more and more different from their →parents to any conceivable extent.

Such

....

differences

Differences

→in the larva might, also, become correlated with successive stages of

development;

its development;

so that the

larvæ,

larvæ

larva,

in the first stage, might →come to differ greatly from the

larvæ

larva

in the second stage, as →is the case with

cirripedes.

many animals.

The adult might

become

also become

fitted for sites or habits, in which organs of locomotion or of the senses, &c., would be useless; and in this case the

final

....

metamorphosis would be →OMIT retrograde.

From the remarks

above

just

made we can see how by

alterations

changes

of structure in the young, in conformity with

altered

changed

habits of life, together with inheritance at corresponding ages, →animals might come to pass through stages of development, perfectly distinct from the primordial condition of their adult progenitors. Most of our best authorities are now convinced that the various larval and pupal stages of insects have thus been acquired through adaptation, and not through inheritance from some ancient form. The curious case of Sitaris— a beetle which passes through certain unusual stages of development— will illustrate how this might occur. The first larval form is described by M. Fabre, as an active, minute insect, furnished