Origin of Species Variorum

→ said to be 1859 1860 1861

OMIT 1869 1872

↑ 3 blocks not present in 1859 1860 1861 1869 1872; present in 1866

If, on the other hand, it profited the young to follow habits of life in any slight degree different from those of their parents and consequently to be constructed in a slightly different manner, or if it profited larvæ already having different habits from their parents to change still further their habits, then, on the principle of inheritance at corresponding ages, the young or the larvæ might be rendered by natural selection more and more different from their parents to any conceivable extent. Differences in the larvæ might, also, become correlated with successive stages of development; so that the larvæ in the first stage, might come to differ greatly from the larvæ in the second stage, as is the case with so many animals. The adult might also become fitted for sites or habits, in which the organs of locomotion or of the senses, &c., would be useless; and in this case the final metamorphosis would be said to be retrograde.

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

From the remarks above made we can see how by alterations of structure in the young, in conformity with altered habits of life, together with inheritance at corresponding ages, the metamorphoses of certain animals might first have been acquired, and subsequently transmitted to numerous modified descendants.

→ on this earth have to be classed together, 1859 1860 1861

on this earth, have to be classed together, 1866

can be arranged within a few great classes; 1869 1872

→ have 1859 1860 1861 1866

within each class have, according to our theory, formerly 1869

within each class have, according to our theory, 1872

→ by fine 1861 1866

by the finest 1859 1860

together by fine 1869 1872

→ on my view 1859 1860 1861

on this view 1866

OMIT 1869 1872

→ groups 1859 1860 1861

or more groups 1866 1869 1872

→ if 1859 1860 1861 1866 1869

in their adult condition, if 1872

→ the same or 1859 1860 1861

closely 1866 1869 1872

→ the same or nearly similar parents, 1859 1860 1861

the same parent-form, 1866

one parent-form, 1869 1872

→ in that degree 1859 1860 1861

OMIT 1866 1869 1872

→ descent. 1859 1860 1861

descent; but dissimilarity in embryonic development does not prove discommunity of descent, for in one of two groups all the developmental stages may have been suppressed, or may have been so greatly modified as no longer to be recognised, through adaptations, during the earlier periods of growth, to new habits of life. 1866

descent; but dissimilarity in embryonic development does not prove discommunity of descent, for in one of two groups the developmental stages may have been suppressed, or may have been so greatly modified through adaptation to new habits of life, as to be no longer recognisable. 1869 1872

→ It will reveal this community of descent, however much the structure of 1859 1860 1861

Community of descent will, however, often be revealed, although the structure of 1866

Even in groups, in which 1869

→ modified and obscured; 1859 1860 1861

greatly modified and thus obscured; 1866

modified to an extreme degree, community of origin is often revealed by the structure of the larvæ; 1869

→ can 1859 1860 1861

though externally so like shellfish, can 1866

though externally so like shell-fish, are 1869

→ embryonic state of each species and group of species partially 1859 1860 1861

embryonic state of each species and group of species 1866

structure of the embryo generally 1869

embryo often 1872

→ the 1859 1860 1861

more or less completely the 1866

more or less plainly the 1869 1872

→ ancient progenitors, 1859 1860 1861 1866

and ancient progenitor, 1869

and ancient progenitor of the group, 1872

→ of life should resemble 1859 1860 1861 1866

so often resemble 1869

so often resemble in their adult state 1872

→ their descendants,— our 1859 1860 1861

our 1866

OMIT 1869 1872

→ species. 1859 1860 1861

species, their descendants. 1866

species in the same class. 1869

species of the same class. 1872

→ but I am bound to confess that I only hope 1859 1860 1861 1866

and I hope 1869

and we may hope hereafter 1872

→ the law hereafter proved 1859 1860 1861 1866

it hereafter shown in most cases 1869

the law proved 1872

&c., would be useless; and in this case the

~~final~~

final

metamorphosis would be →said to be retrograde. ↑ ↑

As all the organic beings, extinct and recent, which have ever

lived,

lived

→on this earth have to be classed together, and as all →have been connected →by fine gradations, the best,

or,

and,

or indeed,

if our collections were nearly perfect, the only possible arrangement, would be

genealogical.

genealogical;

Descent

descent

being →on my view the hidden bond of connexion which naturalists have been seeking under the term of the

Natural

natural

System.

system.

On this view we can understand how it is that, in the eyes of most

natu- ralists,

naturalists,

the structure of the embryo is even more important for classification than that of the adult. For the embryo is the animal in its less modified state; and in so far it reveals the structure of its progenitor. In two →groups of

animal,

animals,

however much they may

~~at present~~

at present

differ from each other in structure and

habits

habits,

→if they pass through →the same or similar embryonic stages, we may feel

almost assured

assured

that they

have

all are

have both

descended from →the same or nearly similar parents, and are therefore →in that degree closely related. Thus, community in embryonic structure reveals community of →descent. →It will reveal this community of descent, however much the structure of the

adults

adult

~~may~~

may

have been →modified and obscured; we have seen, for instance, that

cirripedes,

cirripedes

→can at once

known

be recognised

by their larvæ

to belong