Origin of Species Variorum

→ and embryo, are 1869 1872

are 1859 1860 1861 1866

→ not 1872

of structure in such parts not 1869

↑ 4 blocks not present in 1869 1872; present in 1859 1860 1861 1866

We must not, therefore, in classifying, trust to resemblances in parts of the organisation, however important they may be for the welfare of the being in relation to the outer world. Perhaps from this cause it has partly arisen, that almost all naturalists lay the greatest stress on resemblances in organs of high vital or physiological importance. No doubt this view of the classificatory importance of organs which are important is generally, but by no means always, true. But their importance for classification, I believe, depends on their greater constancy throughout large groups of species; and this constancy depends on such organs having generally been subjected to less change in the adaptation of the species to their conditions of life.

↑ 7 blocks not present in 1859 1860 1861 1866 1872; present in 1869

That the mere physiological importance of an organ does not determine its classificatory value, is almost proved by the fact, that in allied groups, in which the same organ, as we have every reason to suppose, has nearly the same physiological value, its classificatory value is widely different. No naturalist can have worked at any group without being struck with this fact; and it has been fully acknowledged in the writings of almost every author. It will suffice to quote the highest authority, Robert Brown, who, in speaking of certain organs in the Proteaceæ, says their generic importance, "like that of all their parts, not only in this, but, as I apprehend, in every natural family, is very unequal, and in some cases seems to be entirely lost." Again, in another work he says, the genera of the Connaraceæ "differ in having one or more ovaria, in the existence or absence of albumen, in the imbricate or valvular æstivation. Any one of these characters singly is frequently of more than generic importance, though here even when all taken together they appear insufficient to separate Cnestis from Connarus." To give an example amongst insects: in one great division of the Hymenoptera, the antennæ, as Westwood has remarked, are most constant in structure; in another division they differ much, and the differences are of quite subordinate value in classification; yet no one will say that the antennæ in these two divisions of the same order are of unequal physiological importance. Any number of instances could be given of the varying importance for classification of the same important organ within the same group of beings.

→ position 1861 1866 1869 1872

rudimentary florets are 1859 1860

→ rudimentary florets is 1861 1866 1869 1872

highest importance in the classification 1859 1860

→ highest importance in the classification of the grasses. 1872

Grasses. 1859 1860

highest importance in the classification of the Grasses. 1861 1866 1869

whereas the organs of reproduction, with their product the

seed,

seed

→and embryo, are of paramount importance! So again in formerly discussing

~~certain~~

certain

morphological

differences

characters

which are not

physiologically

functionally

important, we have seen that they are often of the highest service in classification. This depends on their constancy throughout many allied groups; and

the

their

constancy

depends chiefly

chiefly depends

on any slight deviations →not having been preserved and accumulated by natural selection, which acts only on

useful

serviceable

characters. ↑

That the mere physiological importance of an organ does not determine its classificatory value, is almost

shown

proved

by the

one

....

fact, that in allied groups, in which the same organ, as we have every reason to suppose, has nearly the same physiological value, its classificatory value is widely different. No naturalist can have worked

long at

any group without being struck with this fact; and it has been

most

....

fully acknowledged in the writings of almost every author. It will suffice to quote the highest authority, Robert Brown,

who

who,

in speaking of certain organs in the

Proteaceæ,

Proteacæ,

says their generic importance, "like that of all their parts, not only in

this

this,

but, as I apprehend, in every natural family, is very unequal, and in some cases seems to be entirely lost."

Again

Again,

in another work he says, the genera of the Connaraceæ "differ in having one or more ovaria, in the existence or absence of albumen, in the imbricate or valvular æstivation. Any one of these characters singly is frequently of more than generic importance, though here even when all taken together they appear insufficient to separate Cnestis from Connarus." To give an example amongst

insects,

insects:

in one great division of the Hymenoptera, the antennæ, as Westwood has remarked, are most constant in structure; in another division they differ

much

much,

and the differences are of quite subordinate value in classification; yet no one

probably

....

will say that the antennæ in these two divisions of the same order are of unequal physiological importance. Any number of instances could be given of the varying importance for classification of the same important organ within the same group of beings. ↑

Again, no one will say that rudimentary or atrophied organs are of high physiological or vital importance; yet, undoubtedly, organs in this condition are often of

high

much

value in classification. No one will dispute that the rudimentary teeth in the upper jaws of young ruminants, and certain rudimentary bones of the leg, are highly serviceable in exhibiting the close affinity between

Ruminants

ruminants

and

Pachyderms.

pachyderms.

Robert Brown has strongly insisted on the fact that the →position of the →rudimentary florets is of the →highest importance in the classification of the grasses.