Origin of Species Variorum

↑ 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.

→ rudimentary florets are 1859 1860

position 1861 1866 1869 1872

→ highest importance in the classification 1859 1860

rudimentary florets is 1861 1866 1869 1872

→ Grasses. 1859 1860

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

highest importance in the classification of the grasses. 1872

→ important an aid 1859 1860 1861

an aid as important 1866

an important aid 1869 1872

in another division they differ

much

much,

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

~~probably~~

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

much

high

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 →rudimentary florets are of the →highest importance in the classification of the →Grasses.

Numerous instances could be given of characters derived from parts which must be considered of very trifling physiological importance, but which are universally admitted as highly serviceable in the definition of whole groups. For instance, whether or not there is an open passage from the nostrils to the mouth, the only character, according to Owen, which absolutely distinguishes fishes and reptiles— the inflection of the angle of the

lower jaw

jaws

in Marsupials— the manner in which the wings of insects are folded— mere colour in certain Algæ— mere pubescence on parts of the flower in grasses— the nature of the dermal covering, as hair or feathers, in the Vertebrata. If the Ornithorhynchus had been covered with feathers instead of hair, this external and trifling character

would

would,

~~I think,~~

I think,

have been considered by naturalists as →important an aid in determining the degree of affinity of this strange creature to