Origin of Species Variorum

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

For the embryo is the animal in its less modified state; and in so far it reveals the structure of its progenitor.

→ or more groups 1866 1869 1872

groups 1859 1860 1861

→ if 1859 1860 1861 1866 1869

in their adult condition, if 1872

→ closely 1866 1869 1872

the same or 1859 1860 1861

→ one parent-form, 1869 1872

the same or nearly similar parents, 1859 1860 1861

the same parent-form, 1866

→ OMIT 1866 1869 1872

in that degree 1859 1860 1861

→ 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

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

→ Even in groups, in which 1869

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

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

modified and obscured; 1859 1860 1861

greatly modified and thus obscured; 1866

→ though externally so like shell-fish, are 1869

can 1859 1860 1861

though externally so like shellfish, can 1866

→ structure of the embryo generally 1869

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

embryonic state of each species and group of species 1866

embryo often 1872

→ more or less plainly the 1869 1872

the 1859 1860 1861

more or less completely the 1866

→ and ancient progenitor, 1869

ancient progenitors, 1859 1860 1861 1866

and ancient progenitor of the group, 1872

→ so often resemble 1869

of life should resemble 1859 1860 1861 1866

so often resemble in their adult state 1872

→ OMIT 1869 1872

their descendants,— our 1859 1860 1861

our 1866

→ species in the same class. 1869

species. 1859 1860 1861

species, their descendants. 1866

species of the same class. 1872

→ and I hope 1869

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

and we may hope hereafter 1872

→ it hereafter shown in most cases 1869

the law hereafter proved 1859 1860 1861 1866

the law proved 1872

→ OMIT 1869

now supposed to be represented in many embryos, 1859

now supposed to be represented in existing embryos, 1860 1861 1866

of the progenitor of the group 1872

→ OMIT 1866 1869 1872

in a long course of modification 1859 1860 1861

→ period of growth, or 1861 1869 1872

age, or 1859 1860

period of growth, nor 1866

→ may be true, but yet, owing 1869 1872

of resemblance of ancient forms of life 1859 1860 1861 1866

→ OMIT 1869 1872

embryonic stages of recent forms, may be true, but yet, owing to the 1859 1860 1861 1866

the structure of the embryo is even more important for classification than that of the adult. ↑ In two →or more groups of

animal,

animals,

however much they may

at present

....

differ from each other in structure and

habits

habits,

→if they pass through →closely similar embryonic stages, we may feel

almost assured

assured

that they

have both

have

all are

descended from →one parent-form, and are therefore →OMIT closely related. Thus, community in embryonic structure reveals community of →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. →Even in groups, in which the

adult

adults

may

....

have been →modified to an extreme degree, community of origin is often revealed by the structure of the larvæ; we have seen, for instance, that

cirripedes

cirripedes,

→though externally so like shell-fish, are at once

be recognised

known

by their larvæ

as belonging