Origin of Species Variorum

→ homologous organs, to whatever purpose applied, 1859 1860 1861 1866

different species 1869 1872

→ different species in the same class; 1866

different species of a class; 1859 1860 1861

same class in their homologous organs, to whatever purpose applied; 1869 1872

→ homologous parts constructed on the same pattern 1859 1860 1861 1866

homologous parts 1869

serial and lateral homologies 1872

→ resemblance in an 1859 1860 1861 1866

close resemblance in the 1869 1872

→ homologous parts, which 1859 1860 1861 1866

parts which are homologous, and which 1869 1872

→ from each other 1859 1860 1861 1866

OMIT 1869 1872

→ in different species of the same class of the 1866

in different species of a class of the 1859 1860 1861

in allied though very distinct species of their 1869

of the 1872

→ though 1859 1860 1861 1866 1869

in allied though distinct species, though 1872

→ relation 1859 1860 1861 1866

a greater or less degree in relation 1869 1872

→ through the principle of modifications being 1859 1860 1861 1866

with their modifications 1869 1872

→ corresponding 1859 1860 1861 1866

a corresponding 1869

a corresponding early 1872

→ selection, 1859 1860 1861 1866

through natural selection, 1869 1872

→ and their final abortion, present to us no inexplicable difficulties; on the contrary, their pre- sence might 1866

and their final abortion, present to us no inexplicable difficulties; on the contrary, their presence might 1859 1860 1861

might even 1869 1872

extend the use of this element of descent,— the

one

only

certainly known cause of similarity in organic beings,— we shall understand what is meant by the

Natural

natural

System:

system:

it is genealogical in its attempted arrangement,

with

and

the grades of acquired difference

marked

are marked

by the

terms,

terms

varieties, species, genera, families, orders, and classes.

On this same view of descent with modification,

most of

all

the great facts in Morphology become intelligible,— whether we look to the same pattern displayed

the →homologous organs, to whatever purpose applied, of the →different species in the same class; or to the →homologous parts constructed on the same pattern in each individual animal and plant.

On the principle of successive slight variations, not necessarily or generally supervening at a very early period of life, and being inherited at a corresponding period, we can understand the

~~great~~

great

leading facts in Embryology; namely, the →resemblance in an individual embryo of the →homologous parts, which when matured

will

....

become widely different →from each other in structure and function; and the resemblance →in different species of the same class of the homologous parts or

organs

organs,

→though fitted in the adult

state

members

for

habits

purposes

as different as

possible.

is possible.

Larvæ are active embryos, which have

been

become

specially modified in →relation to their habits of life, →through the principle of modifications being inherited at →corresponding

age.

ages.

these

this

same

principles,—

principle—

and bearing in mind, that when organs are reduced in size, either from disuse or →selection, it will generally be at that period of life when the being has to provide for its own wants, and bearing in mind how strong is the

force

principle

of inheritance— the occurrence of rudimentary organs →and their final abortion, present to us no inexplicable difficulties; on the contrary, their pre- sence might